pexprt getting started: a transformer design example

PExprt

Getting Started: �A Transformer Design Example

September 2002

NoticeThe information contained in this document is subject to change without notice.Ansoft makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Ansoft shall not be liable for errors contained herein or for incidental or consequential damages in connection with the fur-nishing, performance, or use of this material.This document contains proprietary information which is protected by copyright. All rights are reserved.

Ansoft CorporationFour Station Square�Suite 200�Pittsburgh, PA 15219�(412) 261 - 3200

Microsoft® Windows® is a registered trademark of Microsoft Corporation.UNIX® is a registered trademark of UNIX Systems Laboratories, Inc.Saber® is a registered trademark of Synopsis Corporation.PSpice® is a registered trademark of Cadence Corporation.PExprt®, PEmag®, Maxwell SPICE®, SIMPLORER®, and Maxwell 2D® are registered trade-marks of Ansoft Corporation.

© Copyright 2002 Ansoft Corporation

Printing HistoryNew editions of this manual include material updated since the previous edition. The manual print-ing date, indicating the manual’s current edition, changes when a new edition is printed. Minor cor-rections and updates incorporated at reprint do not cause the date to change.Update packages may be issued between editions and contain additional and/or replacement pages to be merged into the manual by the user. Pages which are rearranged because of changes on a pre-vious page are not considered to be revised.

Edition Date Software Revision

1 September 2002 5.0

iii

Typeface ConventionsField Names Bold type is used for on-screen prompts, field

names, and messages.

Keyboard Entries Bold type is used for entries that must be entered as specified. Example: Enter 0.005 in the Nonlinear Residual field.

Menu Commands Bold type is used to display menu commands selected to perform a specific task. Menu levels are separated by a forward slash.For example, the instruction “Choose File/Open” means to choose the Open command on the File menu.

Variable Names Italic type is used for keyboard entries when a name or variable must be typed in place of the words in italics. For example, the instruction “copy filename” means to type the word copy, to type a space, and then to type the name of a file, such as file1.

Emphasis and Titles

Italic type is used for emphasis and for the titles of manuals and other publications.

Keyboard Keys Bold type, in a different font, is used for labeled keys on the computer keyboard. For example, the instruction “Press Return” means to press the key on the computer that is labeled Return.

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InstallationBefore you use PExprt, you must:1. Set up your system’s graphical windowing system.2. Install the Ansoft software, using the directions in the Ansoft PC Installation Guide.If you have not yet done these steps, refer to the Ansoft installation guides and the documentation that came with your computer system, or ask your system administrator for help.

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Other ReferencesFor more information on PExprt commands and features, refer to the PExprt online help. To start PExprt, you must first access the Maxwell Control Panel. For more detailed information on the Maxwell Control Panel commands, refer to the Maxwell Control Panel’s online help system.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1General Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3Sample Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Results to Expect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

2. Creating a PExprt Project . . . . . . . . . . . . . . . . . . . . . . . 2-1Access the Maxwell Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2Start the Project Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3Create a Project Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Create a New Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Enter Project Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

3. Accessing the Software . . . . . . . . . . . . . . . . . . . . . . . . 3-1Open the New Project and Run PExprt . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2PExprt Working Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Input/Output Data Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4Elements Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5Libraries Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6Specify Modeling Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7Specify Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Units of Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Contents-1

4. PExprt Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Types of Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2User's Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2Working with Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Opening Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3Creating New Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Saving Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Closing Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Saving the Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Closing the Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Modifying Elements in the Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Creating New Library Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9Copying Elements in the Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

5. Selecting the Design Library . . . . . . . . . . . . . . . . . . . . 5-1Design Library Role . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Selecting the Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2Selecting Elements in the Design Library . . . . . . . . . . . . . . . . . . . . . . . . 5-3Auto-Select Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

6. Waveform Input Data . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Waveforms Tab of Input/Output Data Area . . . . . . . . . . . . . . . . . . . . . . . 6-2Waveform Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3Defining the Waveform Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

7. Design Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Design Inputs Tab of Input/Output Data Area . . . . . . . . . . . . . . . . . . . . . . 7-2

Design Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

8. Modeling Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1Modeling Options Tab of Input/Output Data Area . . . . . . . . . . . . . . . . . . 8-2

Modeling Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

9. List of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1Starting the Design Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2Using the List of Results Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4

Contents-2

Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-710. Performance Results . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

From List of Results to Performance Results . . . . . . . . . . . . . . . . . . . . . 10-2Exploring the Performance Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

11. Constructive Results . . . . . . . . . . . . . . . . . . . . . . . . . 11-1Exploring the Constructive Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-2

12. Generating Analytical Models . . . . . . . . . . . . . . . . . . 12-1Generating 1D Winding Setup Designs . . . . . . . . . . . . . . . . . . . . . . . . . . 12-2Defining the Model Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-6Generating the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-7

13. Analysis Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1Selecting Analysis Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-2

14. Using PExprt with PEmag . . . . . . . . . . . . . . . . . . . . . 14-1Invoking PEmag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-2Generating a PEmag Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-5Using PEmag Models in PExprt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-7Summary of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-13

Explanation of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-13

15. Linking with SIMPLORER . . . . . . . . . . . . . . . . . . . . . . 15-1Defining the SIMPLORER Model Language . . . . . . . . . . . . . . . . . . . . . 15-2Generating the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-3Using a PExprt Model in SIMPLORER . . . . . . . . . . . . . . . . . . . . . . . . . 15-4

16. Planar Magnetic Component Designs . . . . . . . . . . . . 16-1Setting Up the Planar Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-2

17. Toroidal Component Designs . . . . . . . . . . . . . . . . . . 17-1Setting Up the Toroidal Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-2Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index-1

Contents-3

Contents-4

Introduction

Power Electronics Expert (PExprt) is an interactive, PC-based design tool that uses analytical expressions to design magnetic components such as transformers and inductors. For example, you can use PExprt to design both complex planar components and multi-winding flyback transformers.PExprt produces an optimal magnetic component design based on the waveform or electrical parameters you enter for the power converter and based on the cores, wires, and materials you select from a database. You only need to enter the numerical values, and PExprt automatically com-putes design alternatives.Rather than resulting in a single design alternative, PExprt’s output consists of a complete series of valid designs meeting your specified design objectives. These results can then be evaluated in terms of several criteria, including power loss and temperature rise.PExprt also includes PEmag, a powerful magnetic analysis module based on finite element analysis (FEA). This module conducts a detailed analysis of geometry, frequency, and material effects not considered by PExprt. The PEmag module also generates behavioral models for use in electrical simulators such as SIMPLORER®, PSpice®, or Saber®. Using PExprt, you can:• Design inductors, multi-winding transformers, coupled inductors, and flyback type compo-

nents.• Introduce waveform or converter Data.• Consider boost, buck, boost-buck, forward, push-pull, half-bridge, full-bridge, and flyback

converters.• Optimize constructive parameters, such as core size, core material, number of turns, air gap

length, wire gage, and number of parallel turns.• Calculate performance parameters, such as winding losses, core losses, flux density, DC and

AC resistance, Irms currents, magnetizing inductance, leakage inductance, and temperature rise.

Introduction 1-1

• Consider complex effects, such as skin and proximity effects, fringing flux near the air-gap for energy calculations, and incremental permeability as a function of the field strength.

• Generate model netlists for Maxwell SPICE®, PSpice®, SIMPLORER®, and Saber® electrical simulators.

• Analyze the entire power electronics application of the resulting model, using an additional electrical simulator (PSpice®, SIMPLORER®, or Saber®).

In this guide, you will use PExprt to model a transformer for a Half-Bridge converter, an example that introduces you to the basic functions of the PExprt software.

The goals for this chapter are to:• Understand the general procedure for creating a transformer design in PExprt.• Review the sample problem and the procedure you will use to generate the design and obtain

the design results.

1-2 Introduction

General Procedure

General ProcedureTo design a magnetic component in PExprt, follow this general procedure:1. Select a design library from the list of stock libraries.2. Optionally, select cores, wires, and core materials from the design library. Only the selected

elements are considered in the design process.3. Introduce the waveform specifications.4. Optionally, specify design inputs, such as gap position, geometry, thermal constraints, wire

spacing, maximum flux density, and maximum number of parallel turns.5. Optionally, select modeling inputs, such as winding losses and optimization criteria.6. Generate a list of possible designs that meet your specifications.7. Select a design, and explore one or more performance results, such as core losses, winding

losses, or temperature rise.8. Select a design, and explore one or more constructive results, such as core size, core material,

wire gauge, gap length, or number of turns.9. Use the Modeler menu to do the following:

• Obtain a SIMPLORER, PSpice, Maxwell SPICE, or Saber subcircuit model of your selected design.

• Link with PEmag modeler in order to:• Optimize the design by generating a new model using another winding strategy.• Compare different winding strategies in order to reduce parasitics (leakage induc-

tance, AC resistance, and capacitances).• Quantify the effect of manufacturing tolerances or material tolerances.• Perform sensitivity analyses.• Analyze the impact of your design within the behavior of the entire circuit (voltage

spikes, efficiency, and ringing).10. Optionally, you can link with SIMPLORER to simulate the entire circuit.

Introduction 1-3

Sample Problem

Sample ProblemIn this guide, you will design, model and simulate a transformer for a Half-Bridge converter, using both wires and planar conductors. You will use the following Half-Bridge converter specifications in your design:• Input Voltage: 50 V• Output Voltage: 5 V• Switching Frequency: 200 kHz• Output Power: 100 W• Duty Cycle: 25%

This getting started guide takes you through the setup, design, and modeling of this magnetic com-ponent. You will cover the following steps:1. Design a low losses transformer from the waveform specifications.2. Model the transformer using both an analytical-based and a FEA-based model, in order to ana-

lyze the impact of the interleaving application on the power losses.3. Simulate the entire converter, including the FEA-based model, with SIMPLORER.4. Design a planar version of the transformer.5. Design a toroidal version of the transformer.

After setting up the problem and generating the solutions, you will do the following:• Select and optimize constructive parameters, including:

• Core size• Core material• Number of turns• Air gap length• Wire gauge• Number of parallel turns

1-4 Introduction

Sample Problem

• Calculate performance parameters, including:• Winding losses• Core losses• Flux density• DC and AC resistance• Irms currents• Magnetizing inductance• Leakage inductance• Temperature rise

• Consider complex effects, including:• Skin and proximity effects• Interleaving applications

• Generate model netlists for the SIMPLORER electrical simulator.• Analyze the entire power electronics application of the resulting model, using SIMPLORER.

Introduction 1-5

Results to Expect

Results to ExpectThe following eight figures show the type of results you can obtain using PExprt:

Input Data Constructive Results

Performance Results List of Results

1-6 Introduction

Results to Expect

Time: The total time needed to complete this getting started guide is approximately 3 hours.

BH Magnetic Material Curve Core Data

AC Resistance FFT of the current

Introduction 1-7

Results to Expect

1-8 Introduction

Creating a PExprt Project

This guide assumes that the following products have already been installed as described in the Ansoft and SIMPLORER installation guides:• PExprt, including the modeling module PEmag• SIMPLORERPlease see the Ansoft PC Installation Guide if you need to install or set up the software.The goals for this chapter are to:• Create a project directory in which to save the sample problems.• Create a new project in that directory in which to save the Half-Bridge transformer problem.

Time: This chapter should take approximately 15 minutes to work through.

Creating a PExprt Project 2-1

Access the Maxwell Control Panel

Access the Maxwell Control PanelTo access PExprt, you must first access the Maxwell Control Panel, which allows you to create and open projects for all Ansoft products.To start the Maxwell Control Panel:• Double-click the Maxwell icon. The Maxwell Control Panel appears.

See the Maxwell Control Panel online documentation for detailed descriptions of other options in the Maxwell Control Panel. If the Maxwell Control Panel does not appear, refer to the Ansoft PC Installation Guide for possible reasons.Next you will create a new project directory in which to store the projects for the PExprt Getting Started guides.

2-2 Creating a PExprt Project

Start the Project Manager

Start the Project ManagerYou can use the Project Manager to create, rename, or delete project files. The Project Manager also allows you to access projects created with other Ansoft products.To access the Project Manager:• Click PROJECTS in the Maxwell Control Panel.The Project Manager appears, listing the current path and any existing projects.


Create a Project Directory

Create a Project DirectoryThe first step in using PExprt to model a magnetic component is to create a project directory and a project in which to save all the data associated with the problem.Project directories contain specific sets of projects created with Ansoft software, categorized in useful ways. For example, you might want to store all projects related to a particular feature or application in one project directory. The Project Manager should still be on the screen. You will now add the getstPExprt directory, which will contain the PExprt project you create using this Getting Started guide.

To create the project directory:1. Click Add from the Project Directories list at the bottom left of the Project Manager window.

The Add a new project directory window appears, listing available directories and subdirec-tories.

2. Double-click on the sub-directory names until the current directory (at the top of the window) is the one where you want to locate the project.

3. Enter getstPExprt in the Alias field. An alias is a project directory name that refers to the cur-

Note: If you have already created a project directory while working through another PExprt get-ting started guide, skip to “Create a New Project” on page 2-6.

Warning: PExprt project names should not contain blank spaces.


Create a Project Directory

rent directory. You can use aliases to refer to project directories located in different computer directories, or across network drive locations.

4. Click the Make New Directory radio button.5. Click OK. The new project directory, getstPExprt, appears in the Project Directories list

under the current default project directory.


Create a New Project

Create a New ProjectNow that you have created the project directory, create a new project named HalfBridgeXfr.The Project Manager should still be on the screen, and the empty getstPExprt project directory should still be selected.To create a new project in the getstPExprt project directory:1. With the getstPExprt directory selected, click New from the Projects list. The Enter project

name and select project type window appears.

2. Enter HalfBridgeXfr in the Name field.3. Select Maxwell PExprt Version 5 from the Type pull-down list. The rest of the list displays

other Ansoft products for which you have licenses.4. Enter your name or user ID in the Created By field.

• If you are using Microsoft Windows NT, 2000, or XP, your login name is automatically entered here.

• If you are using another version of Windows, you may enter your user name or leave the field as is.

5. Deselect the Open project upon creation check box, allowing you to create the new project without immediately launching the software. This allows you to enter project notes before opening the project.

6. Click OK to create the new project.The project name appears in the list of projects in the getstart project directory. Because you created the project, the Status is set to Writable, indicating that you have access to the project.



Enter Project NotesIt is generally a good idea to save notes about the new project so that the next time you use PExprt you can view information about a project without opening it. To enter a description for this project:1. Leave Notes selected. This radio button is selected by default, and the Model option is dis-

abled for PExprt projects, which are only analytical and do not involve a physical model.2. Click in the Notes area (its border is highlighted). 3. Enter the following in the Notes area:

This is a design of a Half-Bridge Converter Transformer using PExprt and the Transformer Design Example Getting Started Guide.

4. Click Save Notes.

You are now ready to open the new PExprt project and run PExprt.

Note: Grayed-out text on commands or buttons means that the command or button is temporarily unavailable. The Save Notes button is grayed out unless there are changes to be saved in the Notes area.


Accessing the Software

In the last chapter, you created the getstPExprt project directory and created the HalfBridgeXfr project within that directory. Now you will open that project in PExprt and start using the software.The goals for this chapter are to:• Open the project you just created and run PExprt.• Learn about the PExprt working window.• Specify your preferences — modeling language, stock libraries, and units.


Accessing the Software 3-1

Open the New Project and Run PExprt

Open the New Project and Run PExprtThe newly created HalfBridgeXfr project should still be highlighted in the Project Manager Projects list. If it is not, click the left mouse button to select it.To open the new project in PExprt:1. Click Open under the Notes area. PExprt opens, and the Selection of Magnetic Component

Type window appears.

2. Click the + symbol in front of Transformer to expand the tree.

3-2 Accessing the Software

Open the New Project and Run PExprt

3. Select the Waveform Based transformer type.

4. Click OK. The PExprt working window appears.


PExprt Working Window

PExprt Working WindowThe PExprt working window is divided into four sections: the Input/Output Data area, the Ele-ments Information area, the Libraries area, and the Graphical Information area.

Input/Output Data AreaThe Input/Output Data area contains different tabs, depending on the design status. The following three tabs are the ones that initially appear:• Waveforms tab: Use this tab to define the waveform specifications.• Design Inputs tab: Use this tab to define the design inputs.• Modeling Options tab: Use this tab to define the modeling options.Use this area to define inputs and other specifications. When you change parameters in the Input/Output Data area, the values for related parameters in that window are automatically updated. The graph is also automatically updated in the Graphical Information area.

ElementsInformation area

Libraries area

Input/Output Data area

Graphical Information area


PExprt Working Window

Elements Information AreaThe Elements Information area contains information about each element included in the libraries. When you click an element in the library tree, its information is displayed in this area.

Libraries AreaThe Libraries area contains a tree with the stock and design libraries used in PExprt. Each library contains cores, bobbins, wires, insulators, and core materials. To view the elements included in each library, click the + symbol to expand the tree.

Graphical Information AreaThe Graphical Information area displays different type of graphical information, depending on the design status and which tab is selected in the Input/Output Data area.


Preferences

PreferencesThere are several options you can specify before working with PExprt. When you click Options/Preferences, the Preferences window appears.

This window has two tabs:• Modeling Language tab: Use this tab to specify the model language (Maxwell SPICE, PSpice,

Saber, or SIMPLORER) to be used to write the model netlists.• Stock Libraries tab: Use this tab to specify the libraries that you want to be opened with any

new design.These tabs are explained in the following sections.


Preferences

Specify Modeling LanguagePExprt generates magnetic component models to be used in three different electrical simulators: Maxwell SPICE, PSpice and Simplorer.To specify the default language:1. Click the Modeling Language tab in the Preferences window.

2. Click the Simplorer button to select SIMPLORER as the modeling language.3. Click Apply or OK at the bottom of the window.

Specify Stock LibrariesPExprt package includes different libraries in order to make easier you design process. Although you can open, close and save libraries during the magnetic component design, you can also select which libraries you want to be loaded with any new design.See Chapter 4, “PExprt Libraries” for a detailed description of PExprt libraries.

Note: The first time you use PExprt, all the libraries included with PExprt are loaded. If you make any changes, they apply the next time you open a new document.


Preferences

To specify the default libraries:1. Click the Stock Libraries tab in the Preferences window.

2. To load a new stock library:a. Click Add New. The Browse Libraries window appears.b. Find and select the library you want to add, and click Open. The new library appears in

the list.3. To remove a library from the list:

a. Select a library from the Libraries to be loaded as “Stock” list.b. Click Remove. The library is removed from the list. The next time you open a PExprt

design, the removed library does not appear in the Stock Library tree. 4. Click OK at the bottom of the window.

Note: In this example project, you do not need to add or remove any libraries in the Preferences window.


Units of Measurement

Units of MeasurementYou can also specify the unit of length you want to use in PExprt. For this example, you want to use millimeters.To specify millimeters as the unit of length:1. Choose Options/Units. The Units window appears.

2. Select Millimeters, and click OK.


Units of Measurement


PExprt Libraries

PExprt works with libraries in order to select elements (for example, cores, wires, core materials) that you want to be considered during the design process. The goals for this chapter are to:• Learn about the types of libraries available in PExprt.• Work with PExprt libraries.


PExprt Libraries 4-1

Types of Libraries

Types of LibrariesPExprt libraries contain the cores, bobbins, wires, and core materials needed to design magnetic components. Two different types of libraries are available in PExprt: stock libraries and design libraries. They are displayed in the Libraries area, in the lower-left portion of the PExprt working window.

Stock LibrariesThese libraries are included with PExprt and are saved in the /PExprt_Install/Lib/PExprt direc-tory, where PExprt_Install is the location where you installed PExprt. Seven libraries are provided with the PExprt installation: • Ferroxcube (former Philips)• Epcos (former Siemens)• TDK• Magnetics• AVX• Micrometals• StewardStock libraries are locked, and you cannot modify them. Once you drag a stock library into the design library folder, the new copy is editable, but the original stock library remains locked.

User's Stock LibrariesYou can create your own stock libraries in order to introduce elements you commonly employ in your applications. These libraries can be composed of custom elements, as well as any of the ele-ments contained in the stock libraries. You can name, save, modify, and lock/unlock user stock libraries.

Design LibraryA project’s design library is the only library that is considered during the design process. All or part of the elements in this library are included during the design process. You specify a design library for your project by dragging one from the stock library tree in the Libraries area of the PExprt working window.

Stock Libraries

User’s Stock LibraryDesign Libraries

4-2 PExprt Libraries

Working with Libraries

Working with LibrariesBefore designing a magnetic component, you first need to load stock libraries so that they appear in the Libraries area of the PExprt working window.

Opening Stock LibrariesThe first time you run PExprt, all libraries included with PExprt are loaded with any new project. You can change this using the Stock Libraries feature on the Options/Preferences menu, as was explained in “Specify Stock Libraries” on page 3-7.To load additional stock libraries:1. Click the Libraries/Stock Libraries/Load Stock Library menu, as shown below:

2. Use the browser to select the desired library.3. After you load a new stock library, that library appears under the Stock Libraries tree in the

Libraries area.



Creating New Stock LibrariesTo create your own stock library:1. Click Libraries/Stock Libraries/New Stock Library. A new library named User Library

appears under the Stock Libraries tree.

Saving Stock LibrariesTo save a stock library:1. Click Libraries/Stock Libraries/Save Stock Library or Library/Stock Libraries/Save

Stock Library As. The Select Library window appears. Only user-created libraries appear in the list of possible libraries to be saved.

2. Select the library you want to save from the list.3. Click OK.

Closing Stock LibrariesTo close any of the stock libraries:• Click Libraries/Stock Libraries/Close Stock Library.



Saving the Design LibraryTo save the design library:1. Click Libraries/Design Library/Save Design Library or Library/Design Library/Save

Design Library As. The Select Library window appears. 2. Select the library you want to save from the list, and click OK.

Closing the Design LibraryTo close the current design library:• Click Libraries/Design Library/Close Design Library.

Modifying Elements in the LibrariesYou can modify elements contained in any unlocked library, allowing you to create your own ele-ments and customize your own libraries. To edit an element, double-click it. The following points describe the library element parameters you can modify:1. Cores: When you double-click a core element (for example RM type), a properties window for

that element appears:

• Click the Core Properties tab of this window to modify the effective values and thermal conductivity.



• Click the Dimensions tab to modify the dimensions of this particular core.

2. Bobbins: When you double-click a bobbin, a properties window for that element appears:

• Use this window to modify the dimensions and thermal conductivity for the selected bob-bin.

3. Wires: When you double-click a wire (for example a SOLID one), a properties window for



that element appears:

• Use this window to modify the dimensions and thermal conductivity for the selected wire.4. Material: When you double-click a core materials, a properties window appears for that ele-

ment:

• Click the Electrical Properties tab of this window to modify the electrical parameters.• Click the Additional Parameters tab to introduce the losses parameters, thermal conduc-

tivity, and dependency of the permeability with the magnetic field strength, as shown



below:

• Click the Graphical Information tab to graphically represent the incremental permeabil-ity, core losses and the B-H curve, as shown below:



Creating New Library ElementsUse the Add New command on the shortcut menu to create a new element in an unlocked library.To create a new element:1. Right-click the element type. For example, to create a new PQ core, right-click the PQ label. A

shortcut menu appears.2. Select Add New from the shortcut menu.

A new PQ core, named New Core, appears at the end of the PQ cores list.

Copying Elements in the LibrariesYou can drag and drop elements from any stock library to the design library.

Note: Elements are copied element by element; you cannot copy an entire type of elements. For example, it is not possible to copy all ETD cores from one of the stock libraries by dragging the ETD label. You must copy each individual ETD core.


Selecting the Design Library

In Chapter 3 you opened the HalfBridgeXfr project, explored the PExprt working window, and reviewed the general procedure for creating a magnetic component design with PExprt. In Chapter 4 you learned how to work with PExprt libraries. You are now ready to start defining the project for the Half-Bridge transformer design; the first step is to define the design library.The goals for this chapter are to:• Understand the role of the design library in the design process.• Define the design library for the Half-Bridge transformer sample project.


Selecting the Design Library 5-1

Design Library Role

Design Library RoleThe PExprt design engine calculates the power losses of all possible combinations of cores, wires, and cores materials that are selected using the specified design library. Using the design library, you can do the following:• Define design constrains selecting part or only one of the cores, wires, and core materials con-

tained in the design library.• Consider multiple combinations of the various cores, wires, and core materials contained in the

design library.The design library is the library that contains the elements considered for the final design. Any ele-ment not included the design library is ignored during the design process.You can select the elements you want to include in the design library or allow PExprt to automati-cally select the elements for you, based on encoded design criteria described later. See the section “Auto-Select Feature” on page 5-5 for more information on how PExprt selects elements for you.

Selecting the Design LibraryYou select the design library by dragging one of the loaded stock libraries and dropping it onto the Design Library tree folder in the Libraries area of the PExprt working window. In this example, you are going to use the Ferroxcube library as the design library.To specify the design library:• Drag the Ferroxcube library from the Stock Library tree folder, and drop it onto the Design

Library tree folder.A copy of Ferroxcube library, named Ferroxcube_Design, appears under the Design Library tree.

Note: The stock libraries included with PExprt are locked and cannot be modified. Any library created by the user can be modified. Once you copy a stock library, into the design library folder, you can then modify the copied version.

5-2 Selecting the Design Library

Design Library Role

Selecting Elements in the Design LibraryOnce you have specified a design library, you can identify constraints for your design by selecting particular elements to be considered in your design. If you skip this step, PExprt automatically selects these elements for you using the Auto-Select feature.This example guides you through selecting the wire gauge but allows PExprt to select the other ele-ments (cores and core materials) using Auto-Select.To select the wire gauge:1. Click the Wires tab in the Libraries area of the PExprt working window.2. Expand the Ferroxcube_Design library tree by clicking the + symbol in front of its name.

3. Expand the SOLID wire type by clicking on the "+" symbol in front of it.


Design Library Role

4. Right-click the AWG17, AWG19, AWG21, AWG23, and AWG25 elements to select them. A tool icon appears next to each element that has been selected.

You could repeat the steps above to select core shapes and core materials from the design library but will allow PExprt to use the Auto-select feature to specify those elements.

Note: To select all the elements contained in under a tree, right-click the type name label, and select Select All.


Design Library Role

Auto-Select FeatureIf you do not select elements on your own from the design library, PExprt can do so for you using its AutoSelect feature. The Auto-Select feature is applied just before starting the design procedure, immediately after you click Calculations/Start Design Process.PExprt’s Auto-Select feature applies the following default selection criteria when selecting ele-ments:• Core Shapes:

• Inductors and Coupled Inductors: POT, RM, EE, and EP• Transformers and Flyback: RM, EE, and ETD• Planar components: RM, EE, and EI• Toroidal components: Toroids

• Core Sizes:• PExprt selects the size of the cores based on the power handled by the component.

• Wire Type:• PExprt selects solid cylindrical wires for concentric and toroidal designs, and selects toroi-

dal designs and planar conductors for planar designs.• Wire Area:

• PExprt selects one out of every three wires so that different diameters may be considered. • Core Materials:

• PExprt selects a maximum of three core materials, based on the frequency and amplitude of the first harmonic of the current waveform and its DC level.

Note: If the current design library does not contain bobbins for the selected cores, the core shapes and sizes are selected according to the bobbin shapes and sizes of the design library.


Design Library Role


Waveform Input Data

After you have selected the design library and the elements to be considered during the design pro-cess, you need to introduce the waveform specifications. Waveform specifications include wave-form type and voltage shape.The goal for this chapter is to:• Enter waveform specifications.

Note: PExprt can use the Half-Bridge topology included in the standard topologies.

However, this guide shows how to introduce the information using the waveform-based approach. A second PExprt Getting Started Guide, Getting Started: An Inductor Design Example, illustrates the converter-based approach.


Waveform Input Data 6-1

Waveforms Tab of Input/Output Data Area

Waveforms Tab of Input/Output Data AreaTo enter converter specification, click the Waveforms tab in the Input/Output Data area of the PExprt working window.

6-2 Waveform Input Data

Waveform Types

Waveform TypesFor general cases, there are a variety of ways to define waveforms. By introducing the data via the waveform, rather than using the converter topology, offers more flexibility when designing trans-formers for non-standard topologies. There are two types of voltage available to apply to the transformer:• Square• Sinusoidal

If you select Sinusoidal, the graphical information for the waveform is updated as shown below:

If you select Square, two additional choices appear for the voltage shape: • Symmetrical• Asymmetrical

Voltage Current


Waveform Types

A Symmetrical voltage waveform means that the absolute values of the positive and negative lev-els of the voltage are the same. The following combinations are available when using a symmetrical waveform, depending on the center tap selection of the windings:

Case Primary Voltage Primary Current Secondary CurrentSecondary CurrentPrimary and Secondary with NO center tap.Example: Variation of Half Bridge and Full Bridge Converters

Primary with NO center tapped and Secondary with center tap.Example: Half Bridge and Full Bridge Converters

Primary with center tap and secondary with NO center tap.Example: Variation of Push-Pull Converter

Primary and secondary with center tap.Example: Push-Pull Converter


Waveform Types

An Asymmetrical voltage waveform means that the absolute values of the positive and negative levels of the voltage may be different, as shown below:

Voltage Current


Defining the Waveform Data

Defining the Waveform DataAs mentioned in Chapter 1, the specifications of the Half-Bridge converter are as follows:• Input Voltage: 50 V• Output Voltage: 5 V• Switching Frequency: 200 kHz• Output Power: 100 W• Duty Cycle 25%

Using the equations that command the Half-Bridge converter behavior, it is very simple to obtain the waveforms applied to the transformer. These waveforms are shown below:

Primary Winding:

Secondary Winding:


Defining the Waveform Data

To meet the above specifications, you need to enter the waveform parameters in PExprt on the Waveforms tab of the Input/Output Data area.To enter the data, do the following in the Windings Definition table of the Input/Output Data area:1. Enter 25 in the Vpos column for the primary winding (the first row, #1).2. Enter 5 in the Turns ratio column for the primary winding.3. Enter 2 in the Turns ratio column for the secondary winding (the second row, #2).4. Enter 100 in the Power column for the secondary winding. 5. Select the CT check box for the secondary winding to set it to be center tapped.6. Click File/Save to save the project.The following values should now appear in the window:

Note: The non-editable values are updated every time you introduce a value in the grid positions of the Windings Definition table.


Graphical Information Area

Graphical Information AreaThe Graphical Information area of the PExprt working window is used to represent the wave-forms applied to the transformer. The waveform shape and values are updated each time you intro-duce a value in the edit boxes and refocus.You can see primary or secondary waveforms by clicking on the grid control in the Windings Def-inition table. If you click on any parameter for the primary winding row (in the Input/Output Data area), PEx-prt displays the primary winding waveforms (in the Graphical Information area).

If you click on any parameter for the secondary winding row, PExprt displays the secondary wind-ing waveforms.


Design Inputs

After you have selected the design library and introduced the specifications for the waveform, as described in Chapter 6, “Waveform Input Data”, you are ready to design the component and can go on to Chapter 9, “List of Results”. However, before you do so, you may want to customize your design by introducing several optional design inputs.The goal for this chapter is to:• Learn how design parameters impact the final design.


Design Inputs 7-1

Design Inputs Tab of Input/Output Data Area

Design Inputs Tab of Input/Output Data AreaTo enter design inputs:1. Click the Design Inputs tab in the Input/Output Data area of the PExprt working window.

The Design Inputs tab appears in the PExprt working window.

2. For this example, keep the default values.

7-2 Design Inputs


Design ParametersThe Design Inputs tab is shown below with the default values:

These parameters impact the final PExprt design as explained below:

Parameter Available Options Design ImpactGeometry Concentric Component

Planar ComponentToroidal Component

The selected geometry type is applied for the design.

Bobbin Include If this option is not selected, PExprt presents designs with no bobbin. By default, concentric components include a bobbin, and planar components do not include a bobbin. Toroidal components never include a bobbin.

Ventilation Type

LowNormalHigh

This value determines the film coefficient for the radiation of temperature. Low means close environment, while High means forced ventilation. When you select Low, you obtain a higher temperature rise than when you select High for the same specifications.

Parallel Options

Max. Parallel Turns PExprt uses this value for the maximum number of parallel windings to be considered during the design process.

Design Inputs 7-3


Turns Ratio Maximum Variation (as a percentage of the input turns ratio)Exact Value

If you select Exact Value, the exact turns ratio is forced, and PExprt does not optimize the design to find the optimal number of turns for each winding. Ansoft recommends selecting Maximum Variation in order to allow PExprt to find the design with the optimal degree of freedom for the turns ratio.

Winding Setup

2D Winding Setup1D "completely-full" layers1D "Partially-Full"

This parameter determines the most feasible winding strategy in order to create the setup you specify (i.e., to create a 1D analytical-based model or a 2D FEA-based model). The following types of models are available:• 2D Winding Strategy: PExprt allows more

than one winding in the same layer. For example, two parallel windings may be placed in the same layer.

• 1D “completely-full” layers: PExprt fills the layers with turns, filling the entire window height.

• 1D “Partially-Full”: PExprt allows layers partially filled with turns.

Winding Efficiency

Awire/Awinding (Wire area/Winding area)Spacing

The parameter determines how to modify the wire spacing. The worse the winding spacing, the lower the number of wires that fit in the window.

Margin Tapes

% Window Height% Window Width

PExprt presents solutions with the specified top and central margin tape percentages, as shown below:

Top Margin Tape

Central Margin

7-4 Design Inputs


Maximum Temperature Rise

Maximum Temperature Rise PExprt presents solutions with a temperature rise below the this value.

Bmax/Bsat Bmax/Bsat This value is specified as a percentage of the saturation flux density and is the maximum value of flux density PExprt considers for the calculations. (PExprt is not designed to provide components working above saturation value of the flux density.)

Minimum Primary Winding Magnetizing Inductance

Minimum Primary Winding Magnetizing Inductance

PExprt presents solutions with a higher magnetizing inductance than the one specified in this field.

Maximum Number of Layers

Maximum Number of Layers This value is particularly useful in the design of planar components, where the cost of the components depends strongly on the number of layers.

Design Inputs 7-5


Graphical Information AreaThis area of the PExprt working window is used to represent the waveform of the voltage and cur-rent applied to the transformer under design. These waveforms are the same as the ones on the Waveforms tab.See “PExprt Working Window” on page 3-4 for a description of the working window.

7-6 Design Inputs

Modeling Inputs

After you have selected the design library and introduced the specifications of the waveform, as described in Chapter 6, “Waveform Input Data”, you are ready to design the component and can go on to Chapter 9, “List of Results”. However, before you do so, you may want to introduce several optional modeling options, in order to improve the accuracy of the results.The goal for this chapter is to:• Learn how modeling options impact the final design.


Modeling Inputs 8-1

Modeling Options Tab of Input/Output Data Area

Modeling Options Tab of Input/Output Data AreaTo enter modeling options:1. Click the Modeling Options tab in the Input/Output Data area of the PExprt working win-

dow. The Modeling Options tab appears in the PExprt working window.

2. For this example, use the default values.

8-2 Modeling Inputs


Modeling ParametersThe Modeling Options tab is shown below with the default values:

These parameters impact the final PExprt design as explained below:

Parameter Available Options Design ImpactWinding Losses Calculation

Irms and DC ResistanceHarmonics and AC Resistance (Skin)Harmonics and AC Resistance (Dowell)Number of harmonics:

If you account for the Harmonics in the losses calculation, you can specify how many harmonics you want to be considered during the design process. You can introduce this information specifying the number of harmonics or by means of the relative influence of one harmonic with respect to the previous one.

During the design process, there are three possible ways to calculate the losses in the conductors:• Irms and DC Resistance: Winding losses are

calculated as:P = I2rms * RDC

• Harmonics and AC Resistance (Skin): Winding losses are calculated as:P = I2DC * RDC + I

2rms_1 * RAC_1 + �

I2rms_2 * RAC_2 + I2rms_3* RAC_3 + ...

(where Irms_i is the rms value of the harmonic i, and RAC_i is the resistance at the frequency of the harmonic i calculated with the effective area, accounting for the skin effect at each frequency).

• Harmonics and AC Resistance (Dowell): Winding losses are calculated as:P = I2DC * RDC + I

2rms_1 * RAC_1 + �

I2rms_2 * RAC_2 + I2rms_3 * RAC_3 +

...(where Irms_i is the rms value of the harmonic i, and RAC_i is the resistance at the frequency of the harmonic i, calculated with the Dowell equations).

Modeling Inputs 8-3


Optimize number of turns for minimum losses

No OptimizationApply Optimization (for Mode 1 or Mode 2)

If you select No Optimization, PExprt does not iterate to find the lower losses solution for each combination of core/wire/material. If you select Apply Optimization, PExprt optimizes using two possible approaches (Mode 1 or Mode 2). Click More Info to learn more about the two approaches.

8-4 Modeling Inputs


List of Results

Show all solutionsSelection

PExprt calculates all solutions meeting the initial specifications, but you can configure which ones to present. If you select Show all solutions, PExprt shows all meeting specifications. If you select Selection, only those that meet the selection criteria are included on the List of Results tab.To modify the default selection criteria, click the Select Solutions button. In the window that appears, you can specify how the results will be classified (by loss, temperature rise, volume, height, or footprint) and the number of solutions to be shown.

Selection of elements from the Design Library

Apply RestrictionsNo Restriction (all possible configurations)

If you want to use all the elements you have selected in the design library for the design process, select No Restrictions. However, if you have selected many elements in the design library, and you do not know how many of them make sense to be considered in the design, select Apply Restrictions to allow PExprt to select the appropriate elements for your design. You can configure how restrictive the criteria are for the selection by clicking the Configure button. In the window that appears, use the Design Constraints tab to set the restriction level for the selections.To learn more about how PExprt applies restrictions, click the Information tab.

Modeling Inputs 8-5


Graphical Information AreaThis area of the PExprt working window is used to represent the waveform of the voltage and cur-rent applied to the transformer under design. These waveforms are the same as the ones on the Waveforms tab.See “PExprt Working Window” on page 3-4 for a description of the working window.

8-6 Modeling Inputs

List of Results

You are now ready to generate designs and explore the solution results.The goals for this chapter are to:• Generate the design alternatives.• Classify the designs using the List of Results tab in the Input/Output Data area of the PExprt

working window.


List of Results 9-1

Starting the Design Process

Starting the Design ProcessDo the following to start the design process:1. Click the Calculations/Start Design Process menu option. The Auto-Select feature is applied

for any elements you did not previously select in the design library. 2. Click Yes when you are asked if you want to auto-select core shapes and core materials. The

Designing Magnetic Component progress window appears.

3. When the design process is complete, a design report message appears, telling you how many valid designs were obtained from the total number of analyzed designs. In this particular case, PExprt tells you it has obtained 679 valid results out of 735 analyzed designs. Since you selected Solution Selection on the Modeling Options tab, only the 10 best solutions, in terms of losses, are shown.

4. Click OK to dismiss this window. The list of results appears on the List of Results tab of the

9-2 List of Results

Starting the Design Process

Input/Output Data area:

List of Results 9-3

Using the List of Results Tab

Using the List of Results TabThe List of Results tab, in the Input/Output Data area, displays the results of the design process:

Do the following to configure the List of Results tab:1. Click on the header of one of the columns to either:

• Classify that column in ascending or descending order.• Select that particular column to be graphically represented in the Graphical Information

area.

2. Double-click on any of the designs in the list. The Customize List of Results window appears.

Note: The columns containing alphanumerical values will not be graphically represented.

9-4 List of Results


Using this window, you can:• Show or hide columns• Specify the range of values to represent elements in each column.

3. To present solutions with temperature rise below 15º, enter 15 in the Temperature field, the Maximum column.

4. To simultaneously present solutions with a volume below 6000 mm3, enter 6000 in the Vol-ume field., the Maximum column.

5. Click OK to apply the criteria to the List of Results tab.The List of Results tab presents only solutions with a temperature rise below 15º and a volume below 6000 mm3, as can be seen below.

6. Right-click on one of the designs of the List of Results tab, for example, the first one. A short-cut menu appears.

7. Select Copy to My Results from the shortcut menu, as shown below:

A new tab, named My Results, appears in the Input/Output Data area. This tab contains any designs you copied there, as in steps 4 and 5. 8. Click the My Results tab to check that the design specified in steps 4 and 5 is now copied in

List of Results 9-5


this new list, as shown below:

Note: When you save a project using File/Save, File/ Save As, or the toolbar button, the only designs saved with the project are those on the My Results tab. Designs on the List of Results tab window are not saved.

9-6 List of Results


Graphical Information AreaThis area of the PExprt working window is used to graphically represent the information for one of the columns from the List of Results tab in the Input/Output Data area. Initially, the power losses are represented for all the design solutions included on the List of Results tab.

See “PExprt Working Window” on page 3-4 for a description of the working window.

List of Results 9-7


9-8 List of Results

Performance Results

After generating various designs for this particular example, you are now ready to explore the results that PExprt provides for each design on the List of Results tab.The goal for this chapter is to:• Explore the Performance Results tab.


Performance Results 10-1

From List of Results to Performance Results

From List of Results to Performance ResultsAll the design alternatives on the List of Results tab meet your specifications. Now you need to select one of them, so that you can explore its performance results.To explore performance results for a specific design:1. Click the List of Results tab.2. Click on the header for the Power Losses column to classify the list by power loss.

Note: To reverse the order (ascending/descending), click a second time on the column header.

10-2 Performance Results

From List of Results to Performance Results

3. Select the lowest losses design.

4. Click the Performance Results tab.

Note: The results presented on the Performance Results tab correspond only to the design cur-rently selected on the List of Results or My Results tabs.


Exploring the Performance Results

Exploring the Performance ResultsYou are now ready to explore the performance results of the currently selected design.This window contains the following sections:• Input/Output Data area: This area is used to show the numerical values of the performance

results.

• Graphical Information area: This area is used to graphically represent the following parame-ters:• Power Losses distribution: This parameter represents the ratio between core losses and

wire losses. In this example, the core/winding losses sharing is balanced, which is a classi-cal rule of thumb. �

However, there are cases where this sharing may be different for the optimal solution. PExprt looks for the optimal case independently of the core/winding losses sharing and then bases the calculations on the exploration of combinations of "core/wire/core mate-rial" in order to find the optimum solution. Therefore, the loss sharing is simply output information, rather than a function of the optimization goal. Depending on each design (namely on the waveforms applied to the component), the loss sharing could be more or less balanced.

• Window Filling: This parameter represents the ratio between the total wire area in the window and the total air area in the window.

• Window Rate: This parameter represents the ratio between the total winding area (area of



the window where the winding is placed, included the air among turns) and the area of the window where there is not any winding.

The following performance results parameters are shown on the Performance Results tab in the Input/Output Data area of the PExprt working window:1. Losses:

• Core: This performance results parameter represents the losses in the core of the magnetic component under the defined working conditions. To explore the core losses in more detail, click on the core losses value display, which is also a button. When you click this button, the Core Losses window appears, describing how the core losses are calculated (using the Steinmetz equation).



• Winding: This performance results parameter represents the losses in the winding, apply-ing the model that you selected on the Modeling Options tab. In this example, you are considering the skin effect of each harmonic. To explore the winding losses in more detail, click on the winding losses value. The Winding AC Information window appears, dis-playing a plot of the winding resistance as a function of the frequency.

You can change the frequency range of the plot using the Min Freq. and Max Freq. fields.Click the AC Losses tab to plot the contribution of each harmonic to the total winding losses.



Click the Current FFT tab to plot the Fast Fourier Transformation of the current waveform. This information represents the harmonic content of the current waveform.

• Total: This performance results parameter represents the total of the core and winding losses added together.

• Winding (DC): This performance results parameter represents the winding losses, consid-ering only the DC resistance and the Irms.

2. Windings: The Windings area is used to represent the values of any winding.

• Current Density: This performance results parameter represents the current density in the selected winding (the rms current value divided by the cross-section area of the wire). Par-allel wires are taken into account.

• Magnetizing Inductance: This performance results parameter represents the magnetizing inductance referred to the selected winding.



• Voltage: This performance results parameter represents the voltage "seen" from the selected winding, considering the turns ratio of the final design.

• Losses (selected model): This performance results parameter represents the losses in the selected winding under the defined current waveform. To learn about how this value is calculated, click on the Losses (selected model). The Windings AC Information win-dow appears, listing a detailed explanation about the losses calculation. This window can also be opened by clicking on the Losses/Windings value as explained earlier.

• Losses (DC): This performance results parameter represents the DC losses in the selected windings under the defined current waveform. To learn about how this value is calculated, click on the Losses (DC) value. The Winding DC Information window appears, listing a detailed explanation about the DC losses calculation.

• DC Resistance: This performance results parameter represents the DC resistance of the winding. To explore the DC resistance in more detail, click on the DC Resistance value or



the Losses (DC) value. The Winding DC Information window appears.

• Irms: This performance results parameter represents the root medium square (rms) value of the current waveform.

3. Window Occupancy:

• Window Filling: This performance results parameter represents the ratio between the total wire area in the window and the total air area in the window.

• Window Rate: This performance results parameter represents the ratio between the total winding area (area of the window where the winding is placed, including the air among turns) and the area of the window where there is no winding.

4. Leakage Inductance:

• DC Value: This performance results parameter represents the low frequency value of the leakage inductance.

• Switching frequency value: This performance results parameter represents the value of



the leakage inductance at the switching frequency.

5. Flux Density:

• Variation of B: This performance results parameter represents the variation of the flux density in mT (tesla * 10-3).

• Maximum B: This performance results parameter represents the maximum value of the flux density in mT (tesla * 10-3).

6. Temperature Rise:

• Temperature Rise: This performance results parameter represents the temperature rise (difference of temperature between the external air and the hottest point) in degrees centi-grade.

Note: The leakage inductance values are only available for designs with a 1D winding strategy. If the design presents a 2D winding strategy, this value is set to "NA" (Not Available).

Note: PExprt is not designed to provide designs above saturation flux density. Therefore, the max-imum B value always presents a value below the saturation B value.


Constructive Results

By now you have generated the designs for this particular example, and you have explored the Per-formance Results tab in the Input/Output Data area of the PExprt working window. You are now ready to explore the Constructive Results tab, which PExprt provides for each design on the List of Results tab.The goal for this chapter is to:• Explore the Constructive Results tab.


Constructive Results 11-1

Exploring the Constructive Results

Exploring the Constructive ResultsTo view the constructive results:• Click the Constructive Results tab in the Input/Output Data area of the PExprt working

window. The following window appears, displaying the Constructive Results tab in the Input/Output Data area and the cross-section of the current design in the Graphical Information area:

Note: The results presented on the Constructive Results tab correspond to only one design -- the design that is currently selected on either the List of Results tab or the My Results tab.

11-2 Constructive Results


The following constructive results parameters are shown on the Constructive Results tab in the Input/Output Data area of the PExprt working window:1. Component:

• Core Size: This parameter represents the core size and name for the selected design.• Bobbin: This parameter represents the bobbin size and name for the selected design.• Core Material: This parameter represents the core material name for the selected design.• Library: This parameter represents the name of the library that has been used as the

design library for the selected design.2. Windings:

• Wire: This parameter represents the wire gauge (AWG) and name for the selected �winding.

• Number of Turns: This parameter represents the number of turns for the selected �winding.

• Parallel Turns: This parameter represents number of parallel turns for the selected �winding.

Constructive Results 11-3


You can explore the constructive elements by clicking on the "element value" button. For example, if you want to explore the core properties, click on the ETD29 button for the Core Size field.

11-4 Constructive Results

Generating Analytical Models

PExprt includes an advanced modeling package that enables you to create accurate models of the generated designs. The modeling module, called PEmag®, allows you to generate analytical-based or finite element-based models. You can link directly between the design module (PExprt) and the modeling module (PEmag), as described in Chapter 14, “Using PExprt with PEmag”.However, if you want to quickly generate an analytical model of your design without opening PEmag, you can use the modeling feature of PExprt, which uses the same modeling generation engine as PEmag analytical model.Since the modeling strategy applied to generate the model is based on analytical expressions, only magnetic component designs that present a one-dimensional (1D) field distribution can be modeled using this approach. Therefore, this feature is only enabled if the selected design presents a 1D field distribution.

The goals for this chapter are to:• Generate "1D Winding Setup" designs.• Define the model language (Maxwell SPICE, PSpice, Saber, or SIMPLORER).• Generate the analytical-based model.

Note: Magnetic components with a single conductive sublayer in each layer can be modeled using an analytical-based model. If the magnetic component contains more than one conductive sublayer per layer, only FEA-based modeling can be used through PEmag. For example, designs with several parallel strands in the same layer are considered as 2D. Designs with primary and secondary windings at the same layer are also considered 2D.If the modeling feature is grayed-out, then the selected design cannot be modeled using ana-lytical expressions.


Generating Analytical Models 12-1

Generating 1D Winding Setup Designs

Generating 1D Winding Setup DesignsTo generate an analytical model directly from PExprt, you need to force PExprt to provide designs presenting a 1D winding strategy.

To force PExprt to generate a 1D winding strategy design:1. Click the Design Inputs tab in the Input/Output Data area of the PExprt working window.2. Select 1D “completely-full” layers in the Winding Setup area.

3. Click the Calculations/Start Design Process menu option. PExprt calculates the designs for the same input specifications but fills the entire window height with turns. Once the design procedure is finished, a dialog below appears telling you how many valid designs were obtained. In this example, PExprt obtained 16 valid designs out of 585 combinations.

Note: PExprt includes the modeling module (PEmag), which enables you to generate FEA-based models valid for any winding strategy. The purpose of this section is to describe how to obtain designs presenting 1D winding strategies.

Note: When you force PExprt to obtain a "1D Completely-full layers" design, the solutions are not optimized for the number of turns. Since PExprt fills the layers with turns, the number of turns is not a degree of freedom for optimization. Therefore, the resulting design may be far from the optimal one.

Note: Usually this option is set to 2D Winding Setup to obtain any winding strategy. The reason you are now setting this value to 1D “completely-full” layers is so that you can generate an analytical models for any of the solutions. If the winding strategy presents a 1D field distribution, PExprt generates analytical models very quickly. However, if the winding strategy presents a 2D field distribution, PExprt may invoke the Maxwell 2D FEA solver in order to generate the model. Therefore, the purpose of this option is so that you can generate models for many solutions in a short time. Ansoft recommends that you read the PEmag documentation to learn which effects are and are not considered by the analytical model.

12-2 Generating Analytical Models


4. Click OK to dismiss the window. The new list of results appears on the List of Results tab.

5. Double-click on any of the designs of the List of Results tab. The Customize List of Results window appears.

6. Enter 6000 in the Volume field to specify the maximum volume allowed.

Note: There are elements in the list of results with a "core icon" . This means that these designs fulfill the exact turns ratio specification. The designs without this icon present a turns ratio in the band that you specified on the Design Inputs tab.



7. Click OK to apply the criteria. The List of Results tab presents only solutions with volume below 6000 mm3.

As explained before, these results may be far from the optimal ones because the number of turns has not been optimized. Depending on the case, the results may be closer or further to optimal. In this example, the results obtained forcing the layers to be filled with turns are far from the optimal ones that were previously obtained using the 2D Winding Setup option.�For example, if you select the first design on the List of Results tab and explore the perfor-mance results, you can see that the losses are higher than the optimal ones and that the core/wire losses sharing is unbalanced.

However, the winding strategy does present a 1D distribution, allowing you to generate �analytical-based models. The winding setup can be seen when you click the Constructive



Results tab.�

Note: Although the selected design is far from the optimum one, you will continue using this design throughout the rest of this guide in order to illustrate how to work with the analytical model and the benefits than can be obtained by using this model in your designs. �If you want to learn how to work with the 2D FEA-based model, see the PExprt Getting Started Guide titled Getting Started: An Inductor Design Example.

Note: You can also obtain a “1D winding setup” design by selecting the 2D Winding Setup option on the Design Inputs tab. �If you select the 2D Winding Setup option, PExprt optimizes the number of turns and then place them in the window. If the resulting winding setup is 1D, you will obtain a 1D solution with optimal number of turns.


Defining the Model Language

Defining the Model LanguageDo the following to define the model language:1. Click Options/Preferences. The Preferences window appears.

2. Click Simplorer to select it as the as modeling language.3. Click OK to apply the selection and close the window.


Generating the Model

Generating the ModelDo the following to generate the model:1. Select the first design from the List of Results tab.

2. Click the Modeler/Generate Analytical Model menu option. A message appears, telling you that the 1D model has been successfully generated.

3. Click OK to dismiss this message.You can now use this model in SIMPLORER as any other circuit element. See Chapter 15, “Link-ing with SIMPLORER” for additional information.To explore the model netlist:1. Click the Modeler/View Analytical Model Netlist/Simplorer menu option. Windows Note-

pad opens, displaying the SIMPLORER netlist description.

2. When you are finished viewing the netlist description, click File/Exit to exit Notepad.


Analysis Mode

So far you have been working with PExprt in Design Mode. An alternative way to work with PEx-prt is called Analysis Mode. Analysis Mode works with only a single design, which you select from the List of Results tab. Once you have selected a design, you may want to change a particular parameter of this design and then evaluate the impact of this change on the performance results. This can be done using Analysis Mode. You can also use Analysis Mode to evaluate previous designs with PExprt. In other words, if you have previously designed a magnetic component and you want to evaluate the losses, tempera-ture rise, and other factors of this design, you can use Analysis Mode to introduce this design and then obtain its performance results.The goal for this chapter is to:• Select and work with Analysis Mode.


Analysis Mode 13-1

Selecting Analysis Mode

Selecting Analysis ModeAnalysis Mode works with the design you have previously selected from the List of Results tab. Make sure that you have selected the lower losses design from the List of Results tab before con-tinuing with the example.

To select Analysis Mode:1. Click Calculations/Analysis Mode. Since you previously copied a design to the My Results

tab, in “Using the List of Results Tab” on page 9-4, a message appears telling you the designs on that tab will be deleted.

2. Click Yes to continue. The Constructive Results tab appears, showing the cross-section of the selected design. You can edit several values on the Constructive Results tab: the number of turns and the number of parallel turns.

To modify one of the constructive results values in order to evaluate its impact on the design:1. Change the Parallel Turns field to 2 (instead of the current value of 3 for the parallel wind-

ing).

2. Click Calculations/Analyze Component to evaluate the results. Since you previously gener-ated an analytical model for the current project, a message appears, asking you if you want to remove that model.

3. Click Yes to remove the previously generated model. The Performance Results tab appears, showing the results for the modified design.

Note: There is no design library when working in Analysis Mode. Therefore, the Design Library folder in the library tree is hidden while you are working in this mode.

13-2 Analysis Mode


Reducing the number of parallel turns from 3 to 2 in the primary winding causes the winding losses to increase from 8.85 W in the original design to 9.898 W in the modified design.You can modify all of the constructive parameters while working in Analysis Mode.

Do the following to modify the remaining of the constructive parameters:1. Click the Constructive Results tab.2. Click Cores tab in the Libraries area.

3. Expand the Ferroxcube library.4. Expand the ETD core type.5. Drag the ETD34 core, and drop it on the area where the cross-section of the magnetic compo-

nent is represented (in the Graphical Information area). The new core is represented as shown below:

6. Click the Bobbins tab in the Libraries area.7. Expand the Ferroxcube library.8. Expand the ETD bobbin type.9. Drag the ETD34 bobbin, and drop it on the area where the cross-section of the magnetic com-

Analysis Mode 13-3


ponent is represented. The new cross-section is represented as shown below:

10. Click the Wires tab in the Libraries area.11. Expand the Ferroxcube library.12. Expand the SOLID wire type.13. Drag the AWG20 wire, and drop it on the area where the cross-section of the magnetic compo-

nent is represented. This defines the wire for the first winding. The new cross-section is repre-sented as shown below:

13-4 Analysis Mode


14. Select Winding 2 from the pull-down menu in the Windings area.

15. Expand the Ferroxcube library again in the Libraries area.16. Expand the SOLID wire type again.17. Drag the AWG25 wire, and drop it on the area where the cross-section of the magnetic compo-

nent is represented. This defines the wire for the second winding. The new cross-section is rep-resented as shown below:

After modifying the constructive parameters, save the project and evaluate the results.To save the project:• Click the File/Save menu option.To evaluate the results:• Click the Calculations/Analyze Component menu option. The Performance Results tab

appears, showing the results for the modified design.

Note: If you save the project while working in Analysis Mode, the project is saved in this mode, along with any design modifications you have applied to the selected design.

Analysis Mode 13-5


13-6 Analysis Mode

Using PExprt with PEmag

As already mentioned, the PExprt package includes a powerful modeling module, PEmag, which allows you to generate models of the designs created using PExprt. PEmag allows you to modify the winding setup of the current design in order to evaluate the impact of different constructive parameters. Using PEmag you can:• Optimize the design by generating a new model using another winding strategy.• Compare different winding strategies in order to reduce parasitics (leakage inductance, AC

resistance, and capacitances).• Quantify the effect of the manufacturing tolerances.• Quantify the effect of the material tolerances.• Perform sensitivity analyses.• Analyze the impact of your design on the behavior of the entire circuit (voltage spikes, effi-

ciency, and ringing).You can work with PEmag as an additional add-on module within PExprt or as a standalone appli-cation.

The goals for this chapter are to:• Link PExprt with PEmag.• Extract information from the model generated with PEmag.

Note: Refer to the PEmag Getting Started Guides to learn how to use PEmag in detail.


Using PExprt with PEmag 14-1

Invoking PEmag

Invoking PEmagYou can only invoke PEmag after you have generated the List of Results tab and selected a design from the list.Since you have been using the Analysis mode, the initial input parameters may be now different. For example, if you have modified the number of turns of one of the windings, the turns ratio changes. Therefore, you first need to regenerate the original designs before invoking PEmag.To regenerate the original design:1. Click the Calculations/Design Mode menu option to return to Design mode.

2. Click the Waveforms tab. 3. In the Windings Definition table, make sure the Turns ratio values are correct (5:2). If not,

re-enter the Turns ratio values for the primary and secondary windings (5:2).

4. Click the Calculations/Start Design Process menu option to regenerate the design. The List

14-2 Using PExprt with PEmag

Invoking PEmag

of Results tab appears.

Now that you have regenerated the design, select a design from the List of Results tab and invoke PEmag.To invoke PEmag:1. Select the first ETD design from the List of Results tab.2. Click Modeler/Invoke PEmag Modeler. An information message appears telling you that

you are exporting the selected design to the PExprt Modeling Module (PEmag). Nonlinear parameters are not exported to PEmag; therefore, if you need to generate models with nonlin-ear cores in PEmag, you need to introduce the nonlinear core parameters before generating the model.

3. Click OK to dismiss this window.


Invoking PEmag

Since you are working in Analysis Mode, PEmag opens the current design that you previously modified, as shown below:


Generating a PEmag Model

Generating a PEmag ModelIf you are not a PEmag user, Ansoft recommends that you work through the PEmag Getting Started Guides to learn more about the software.To evaluate the impact of the interleaving application in your PExprt design, you are going to gen-erate the analytical based (1D) model of the current design in PEmag.Since the selected design contains three windings connected in parallel, the current flows through those parallel windings in different proportions (not 1/3 though each one). The current distribution through parallel windings depends on the frequency and on the winding strategy. This effect is dif-ficult to accurately model using analytical calculations. The PExprt modeling module (PEmag) cal-culates the real current distribution through parallel windings. PExprt does not calculate the actual current distribution during the design stage (current sharing is assumed), but, once you select a par-ticular design, you can invoke the modeler to obtain an accurate model and then use that model as feedback for PExprt to recalculate the losses. These effects are illustrated in this section.You will learn how to generate the analytical-based model (1D) for two current variations of the same PExprt design:• Without interleaving (initial PExprt design).• With interleaving application among layers.Interleaving application is based on the positioning of the secondary windings in between the pri-mary parallel windings. Applying interleaving improves the current sharing between parallel wind-ings, making the results close to when you assume ideal current sharing. However, if interleaving is not applied, most of the primary current flows through the parallel winding closest to the secondary windings, and losses will be higher than when you assume current sharing. All of these effects can be explored and quantified using PExprt, without any manufacturing or measuring iteration.First, generate the analytical model of the current design, which does not present interleaving appli-cation. To generate the analytical-based model using PEmag:1. From within PEmag, click Modeler/Analytical Modeler (1D)/Start 1D Model Generation.

The Select Analytical Calculations window appears.


Generating a PEmag Model

2. Click the Model + Values button. Once the model is generated, a message window appears, telling you that the analytical values have been successfully calculated.

3. Click OK to dismiss this window.4. Do not close PEmag. You will generate the interleaved model version shortly.You have generated the model of the current design using the PEmag analytical model engine. This model accounts for frequency effects (skin and proximity) more accurately than PExprt models do.

In the next section, you will evaluate the impact of these additional losses due to the parallel con-nections in your current PExprt design.

Note: One important effect is the parallel connections of the windings. PExprt assumes a homogenous distribution of the current through parallel windings (current sharing). PEmag models the effect accurately, calculating the real current distribution through the parallel windings. The impact of this effect can be evaluated using PExprt in combination with PEmag.Refer to the PEmag documentation to learn more about the features of PEmag models.


Using PEmag Models in PExprt

Using PEmag Models in PExprtAfter you have generated the analytical-based model with PEmag, you can use this model to calcu-late the losses in PExprt.To use the PEmag analytical-based model for the losses calculation in PExprt:1. Click the Modeling Options tab in the Input/Output Data area of the PExprt working win-

dow.

2. Select PEmag Analytical Model from the Winding Losses Calculation section.

3. Click Calculations/Analyze Component to evaluate the results. An information window appears, telling you that the waveform may change because PExprt uses the AC resistance and Magnetizing Inductance information from the PEmag FEA based model.

4. Click OK to dismiss this window. The Performance Results tab appears, showing the results.

Note: The PEmag Analytical Model and PEmag FEA based Model options are disabled if the PEmag model has not been previously generated.



If you select Harmonics and AC Resistance (Skin) on the Modeling Options tab for this design, you obtain the losses shown below:

However, if you select PEmag Analytical Model on the Modeling Options tab for this design, you obtain the losses shown below:

In this particular example, the impact of the parallel connections on the losses is about 22 W.Since the PExprt package includes the PEmag modeling module, you can modify the winding strat-egy in order to evaluate the impact on your design.You will now minimize the effect of the parallel windings applying interleaving and quantify the effect without any manufacturing iteration, using the modeling capability of PEmag.To modify the winding strategy in PEmag:1. Click on the red layer. A dashed white rectangle appears at that layer.

2. Click Layer/Copy Layer. The cursor changes shape, indicating that you are in the Copy Layer



mode.3. Click on the first insulator layer from the left. The new copied layer appears at the right side of

the insulator layer.

4. Click on the second insulator layer from the left. The new copied layer appears at the right side of the insulator layer.

5. Click Layer/Remove Layer. The cursor changes shape, indicating that you are in the Remove Layer mode.

6. Remove the four layers at the right by clicking on each of them, one by one. After removing

Note: If you copy the layer in a wrong place, use the Layer/Remove Layer menu command to correct the situation.



them, the connections should appear as shown below:

7. Click Connections/Add. The cursor changes shape, indicating that you are in the Add Con-nection mode.

8. Create the connections by clicking on the round connectors, as shown below:



You have now created the interleaved version of the design, which appears as shown below:

You are now ready to generate the analytical model again with PEmag.To generate the analytical model again with PEmag:1. In PEmag, click Modeler/Analytical Modeler (1D)/Start 1D Model Generation. The Select

Analytical Calculations window appears.2. Click the Model + Values button. Once the model is generated, a message window appears,



telling you that the analytical values have been successfully calculated.3. Click OK to dismiss this window.Compare the results using this winding strategy with the ones previously obtained on page 14-7.As shown previously, to use a PEmag analytical model for the losses calculation in PExprt, do the following:1. Click the Modeling Options tab in the Input/Output Data area of the PExprt working win-

dow.2. Select PEmag Analytical Model from the Winding Losses Calculation section.3. Click Calculations/Analyze Component to evaluate the results. An information window

appears.4. Click OK to dismiss this window. The Performance Results tab appears, showing the results.


Summary of Results

Summary of ResultsThe results are explained below, for the three different situations: • PExprt skin and proximity effects without interleaving• PEmag analytical-based model without interleaving• PEmag analytical-based model with interleaving

PExprt Skin and Proximity Effects Without Interleaving:

PEmag Analytical-Based Without Interleaving:

PEmag Analytical-Based With Interleaving:

Explanation of ResultsBecause PExprt assumes current sharing during the design stage, the resistance that PExprt calcu-lates is obtained assuming that 1/3 of the current flows through each parallel winding. However, in reality, most of the current flows through only one parallel winding -- the one closest to the second-ary winding. This increases the resistance and, also, therefore, the losses.PEmag considers this real situation, allowing you to quantify it. PEmag accomplishes this by allowing you to apply interleaving to modify the winding strategy in order to minimize the effect.


Summary of Results

The current sharing is improved by placing each parallel winding near a secondary winding. By doing this, and using PEmag module, you can see that the current sharing is improved because the losses are reduced to a value close to the ideal current sharing.When parallel windings are used, you can see how important the interleaving application is. Using PExprt in combination with PEmag, you can select the proper winding strategy for each applica-tion. This is critical because a decision in the winding strategy determines the performance of the designed component.


Linking with SIMPLORER

The analytical-based and FEA-models generated using PExprt and PEmag can be linked to differ-ent electrical simulators in order to simulate the behavior of the entire circuit.Ansoft SIMPLORER is one electrical simulator that can be used as part of an entire design pack-age. The combination of PExprt, PEmag, and SIMPLORER provides a unique, powerful way to design, model, and simulate electromagnetic systems.The goal for this chapter is to:• Use SIMPLORER to simulate the behavior of the entire circuit.

Note: Refer to the SIMPLORER User Guide to learn how to use the software in detail.


Linking with SIMPLORER 15-1

Defining the SIMPLORER Model Language

Defining the SIMPLORER Model LanguageIf you have not already done so in Chapter 11, “Constructive Results”, do the following to define the model language:1. Click Options/Preferences. The Preferences window appears.

2. Click Simplorer to select is as the modeling language. 3. Click OK to apply the selection and close the window.

15-2 Linking with SIMPLORER


Generating the ModelTo generate the model:1. Click Modeler/Generate Analytical Model. A message appears, telling you that the 1D

model has been successfully generated.2. Click OK to dismiss the window.You are now ready to open SIMPLORER and use the generated model as part of your circuit.


Using a PExprt Model in SIMPLORER

Using a PExprt Model in SIMPLORERTo use a PExprt model in SIMPLORER:1. Open the SIMPLORER application.2. Click the toolbar button to start the SIMPLORER Schematic.3. Right-click the Users tab. A shortcut menu appears.4. Select Insert Library from the shortcut menu.

5. Use the browser to access the /PExprt_Install/Template/Simplorer/Library directory, where PExprt_Install is the location where you installed PExprt.



6. Select the PExprt.smd library, and click Open. The PExprt library appears on the User tab.

7. Click File/New on the SIMPLORER menu to create an empty schematic.8. Select the User6 library from the Users in the ModelTree area.

9. Right-click in the blank area below the library names. A shortcut menu appears.10. Select Insert/Macro(s) from SML20-File from the shortcut menu.

Note: Steps 3 through 6 should only be performed once. The next time you open SIMPLORER, the PExprt library is automatically loaded.

Note: If you do not have a User6 library, you can create your own user library.



11. Use the browser to access the directory where you saved the PExprt analytical project.12. Select the halfbridgexfr.sml file, and click Open.

The Insert Macro window appears.

13. In the Insert Macro window, click on the buckinductor element of the tree , and then click OK. The new model (buckinductor) appears in the ModelTree area.

14. Drag the model from the ModelTree area, and drop it in the schematic area.

Note: You use the FEA-based model in SIMPLORER in the same way, selecting the FEA-based model instead of the analytical one in steps 12 and 13.


Planar Magnetic Component Designs

More designs are beginning to use planar magnetic components, and PExprt has been designed to work with planar designs using the same philosophy as wire components.The goal for this chapter is to:• Repeat the design of the Half-Bridge converter, this time using planar technology.


Planar Magnetic Component Designs 16-1

Setting Up the Planar Design

Setting Up the Planar DesignYou first need to change back to Design Mode to proceed with the design process.To set up the planar design:1. Click Calculations/Design Mode. Since you previously generated the analytical model for the

current project, a message appears asking if you want to remove that model.2. Click Yes to remove the previously generated model.3. Click Design Inputs tab in the Input/Output Data area of the PExprt working window.4. Select Planar Component as the Geometry.

5. To change the Spacing to reasonable values for a planar design, enter 150 µm in the Intra-layer field and 200 µm in the Inter-layer field.

6. Increase the Max. Parallel Turns value from 3 to 10.

16-2 Planar Magnetic Component Designs


To select appropriate core shapes for a planar design:1. Click the Cores tab in the Libraries area, and expand the Ferroxcube_Design library.

2. Right-click on the RM type, and select Unselect All from the shortcut menu. The RM label now appears in gray, indicating there are no cores selected for that type.

3. Right-click on the EE type, and select Unselect All from the shortcut menu. The EE label now appears in gray, indicating there are no cores selected for that type.

4. Right-click on the ETD type, and select Unselect All from the shortcut menu. The ETD label now appears in gray, indicating there are no cores selected for that type.

5. Expand the RM core type, and right-click to select the RM10/ILP and RM12/ILP cores. (LP stands for Low Profile.) A "tool" icon appears in front of each selected core, as shown below.

6. Click File/Save to save the project.



To start the design process for this planar component:1. Click Calculations/Start Design Process. The Auto-Select feature is applied for the planar

wires parameter. A message appears, asking if you want to allow PExprt to auto-select the wires.

2. Click Yes to have PExprt automatically select the wires. The design process begins. When the design process has completed, a design report message appears, telling you how many valid designs have been obtained from the total number of designs analyzed. In this particular case, PExprt tells you it has obtained 12 valid results out of 191 analyzed designs. Since you speci-fied Solution Selection on the Modeling Options tab, only the best 10 solutions, in terms of losses, are shown.

3. Click OK to dismiss this window. The List of Results tab appears.



You can now explore the performance and constructive results, as explained in Chapter 10, “Perfor-mance Results” and Chapter 11, “Constructive Results”.For example, if you select the first design from the List of Results tab, and then click the �Constructive Results tab, you obtain the cross-section of the planar transformer, as shown below:


Toroidal Component Designs

PExprt has been designed to work with toroidal designs using the same philosophy as concentric components.The goal for this chapter is to:• Repeat the design of the Half-Bridge transformer, this time using a toroidal core.


Toroidal Component Designs 17-1

Setting Up the Toroidal Design

Setting Up the Toroidal DesignTo set up a toroidal design:1. Click Design Inputs tab in the Input/Output Data area of the PExprt working window.2. Select Toroidal Component as the Geometry.

3. To change the Spacing to reasonable values for a toroidal design, select Spacing, and enter 10 % in both the Intra-layer and Inter-layer fields.

To select appropriate core sizes for this particular toroidal design:1. Click the Cores tab in the Libraries area, and expand the Ferroxcube_Design/Toroidal

library.

17-2 Toroidal Component Designs


2. Right-click to select TN14/9/5 and TN14/9/9. A "tool" icon appears in front of each selected core, as shown below:

3. Click File/Save to save the project.

To start the design process for this toroidal component:1. Click Calculations/Start Design Process. The Auto-Select feature is applied for the toroidal

cores and the wires selection. A window appears, asking if you want to auto-select the cores and wires.

2. Click Yes to have PExprt automatically select the cores and wires. The design process begins. When the design process has completed, a design report message appears, telling you how many valid designs have been obtained from the total number of designs analyzed. In this par-ticular case, PExprt tells you it has obtained 467 valid results out of 582 analyzed designs. Since you specified Solution Selection on the Modeling Options tab, only the best 10 solu-tions, in terms of losses, are shown.

Toroidal Component Designs 17-3


3. Click OK to dismiss this window. The List of Results tab appears.

You can now explore the performance and constructive results, as explained in Chapter 10, “Perfor-mance Results” and Chapter 11, “Constructive Results”.For example, if you select the first design from the List of Results tab, and then click the Con-structive Results tab, you obtain the top view of the toroidal transformer, as shown below:

17-4 Toroidal Component Designs

Index

Numerics1D analytical model 12-7

Aalias 2-4Analysis Mode 13-1analytical-based model 15-3analytical-based modeling 12-1Ansoft SIMPLORER 15-1Ansoft software, installing 1-vautomatically select design elements 5-5Auto-Select feature 5-5

Bbobbin 7-3

Cclassifying the list of results 10-2component 11-3constructive results parameters 11-3Constructive Results tab 11-1Control Panel

about 2-2

buttons 2-2starting 2-2

creatingproject directory 2-4projects 2-1, 2-6

criteria for Auto-Select 5-5

Ddefaults for Auto-Select 5-5defining modeling language 12-6Design Inputs tab 7-2, 7-3design library

role 5-2selecting 5-2selecting elements 5-3

Design Mode 13-1design parameters 7-3design process

starting 9-2designing magnetic components

general procedure 1-3designs

generating 9-1directory

alias 2-4project 2-4

dragging stock library to design library 5-2

Index-1

Eelectrical simulators 15-1Elements Information area 3-5English units 3-9

FFEA-based 2D model 14-5flux density 10-10

Ggeneral procedure

creating magnetic components in PExprt 1-3generating designs 9-1geometry 7-3Graphical Information area 3-5grayed-out (text and buttons) 2-7

Iincremental permeability 10-10Input/Output Data area 3-4

Constructive Results tab 11-1Design Inputs tab 7-2List of Results tab 9-4Modeling Options tab 8-2Performance Results tab 10-1Waveforms tab 6-2

installing Ansoft software 1-vintroduction

PExprt 1-1invoking PEmag modeler 14-3

Llibraries

stock 3-6Libraries area 3-5linking to PEmag 14-1list of results settings 8-5List of Results tab 9-4

losses 10-5

Mmargin tapes 7-4Maxwell 3D

installing 1-vMaxwell SPICE 3-6metric units 3-9model

generating analytical model 15-3model language

defining SIMPLORER 15-2modeling

analytical 12-1generating a 1D analytical model 12-7

modeling language 3-6defining 12-6

Modeling Options tab 8-2, 8-3modeling parameters 8-3models

FEA 14-5modes in PExprt 13-1

Nnew project 2-6

Oobjects

drawing 3-1opening projects 3-2optimizing the number of turns for minimum losses 8-

4

Pparameters

constructive results 11-3performance results 10-5

PEmag 14-1generating a model 14-5

Index-2

invoking modeler module 14-3using PEmag models in PExprt 14-7

performance results parameters 10-5Performance Results tab 10-1permeability 10-10PExprt

general procedure for designing magnetic compo-nents 1-3

results to expect 1-6starting 3-2

PExprt projectadd 2-4creating 2-1, 2-6directory 2-4new 2-6notes 2-7opening 3-2

PExprt working window 3-4planar magnetic components 16-1Post Processor

starting 7-6, 13-6, 14-14, 16-5, 17-4Power Electronics Expert (PExprt)

introduction 1-1preferences 3-6

modeling language 3-6stock library settings 3-6units 3-9

Project Managerstarting 2-3window 2-2

PSpice 3-6

Rresults

List of Results tab 9-1results to expect in PExprt 1-6

results, viewing 7-6, 13-6, 14-14, 16-5, 17-4role of design library 5-2

Sselecting a design library 5-2selecting elements from the design library 8-5

selecting library elements 5-3SIMPLORER 3-6, 12-6, 15-1

using a PExprt model 15-4solution results 9-1solutions, generating 5-1starting

Control Panel 2-2PExprt 3-2Post Processor 7-6, 13-6, 14-14, 16-5, 17-4Project Manager 2-3

starting the design process 9-2stock libraries 3-6

Ttemperature rise 10-10toroidal component designs 17-1

Uunits of measurement 3-9

Vventilation type 7-3viewing

results 7-6, 13-6, 14-14, 16-5, 17-4

WWaveforms tab 6-2winding DC losses 10-7winding efficiency 7-4winding losses calculation 8-3winding setup 7-4window

Project Manager 2-2window occupancy 10-9working window 3-4

Index-3

Index-4

pexprt getting started: a transformer design example

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