refrigerator compressor reference design user guide

Refrigerator Compressor Reference Design User Guide

Microchip Technology Inc.

Refrigerator Compressor Reference Design

User Guide

Contents

Safety Notice .............................................................................................................................. 2

Document Revision History ........................................................................................................ 3

Glossary ...................................................................................................................................... 4

1 Introduction .............................................................................................................................. 5

1.1 System and Tools Requirements ................................................................................. 6

1.1.1 Basic requirements ............................................................................................ 6

1.1.2 Advanced requirements ..................................................................................... 6

2 Hardware Description .............................................................................................................. 7

2.1 Introduction ................................................................................................................... 7

2.2 Key Functional Modules ............................................................................................... 8

2.2.1 EMI filter and Protection ..................................................................................... 9

2.2.2 Rectifier ............................................................................................................ 10

2.2.3 Auxiliary power supply ..................................................................................... 10

2.2.4 MCU ................................................................................................................. 11

2.2.5 Inverter circuitry ................................................................................................ 12

2.2.6 Feedback circuitry ............................................................................................ 13

2.2.7 Communication ports ....................................................................................... 14

2.3 User Interface ............................................................................................................. 14

2.3.1 Connectors and Sockets .................................................................................. 14

2.3.2 LED indicators .................................................................................................. 16

2.4 Electrical Specifications .............................................................................................. 17

3 Setup and Run .......................................................................................................................18

3.1 Basic Operation .......................................................................................................... 18

3.2 Run with Diagnostic Kernel ........................................................................................ 21

3.3 Debug and Test by Test Harness .............................................................................. 27

3.3.1 Debug and test operation by Test Harness ..................................................... 28

3.3.2 Brief conclusion of the Test Harness setting.................................................... 30

4 Run a Different Compressor ..................................................................................................32

4.1 Modify theoretical arithmetic parameters ................................................................... 32

4.2 Debug parameters ...................................................................................................... 35

4.2.1 Debug startup parameters ............................................................................... 35

4.2.2 Debug PI parameters ....................................................................................... 36

5 Known Issues ........................................................................................................................38

Appendix A. Flag Description ...................................................................................................39

Appendix B. Schematics ...........................................................................................................40



Safety Notice

The safety notices and operating instructions provided should be adhered to, to avoid

a safety hazard.

WARNING – The input AC mains supply, output terminals and other interfaces are NOT

isolated with each other. DO NOT connect any non-isolated device to the board when input

mains supply voltage applied.

WARNING – The output terminals may be at up to 410V with respect to ground, regardless

of the input mains supply voltage applied. These terminals are live during operation AND

for three minutes after disconnection from the supply. Do not attempt to access the

terminals or remove the cover during this time.

CAUTION – The system should not be installed, operated, serviced or modified except by

qualified personnel who understand the danger of electric shock hazards and have read

and understood the user instructions. Any service or modification performed by the user is

done at the user’s own risk and voids all warranties.

CAUTION – The Reference Design board is designed to be connected to the AC mains

supply via a nonlocking plug. As the unit has no mains switch, this plug constitutes the

means of disconnection from the supply and thus the user must have unobstructed

access to this plug during operation.



Document Revision History

Revision A – 12/4/2019

This is the initial released version of the document.



Glossary

ADC - Analog-to-Digital Converter

ATPLL - Angle Tracking Phase-Locked Loop

DSC - Digital Signal Controller

RCDRD - Refrigerator Compressor Development Reference Design

RCDB - Refrigerator Compressor Development Board

FOC - Field-Oriented Control

IPMSM - Interior Permanent-Magnet Synchronous Motor

LDO -Low Dropout voltage regulator

LED - Light-Emitting Diode

MCU - Micro Control Unit

MTPA - Maximum Torque Per Ampere

Op-Amp - Operational Amplifier

PI - Proportional - Integral

PWM - Pulse-Width Modulation

RMS - Root-Mean-Square

SPMSM - Surface Permanent-Magnet Synchronous Motor

SVPWM - Space Vector Pulse Width Modulation

TTL -Transistor-Transistor Logic

UART - Universal Asynchronous Receiver-Transmitter

USB -Universal Serial Bus



1 Introduction

PMSM motor is getting widely used in household electric refrigerator compressors for its

higher efficiency and lower noise over traditional single-phase AC motor. A typical

refrigerator electrical control system has 2 control boards，one is for refrigerator system

control, another for compressor control.

This Refrigerator Compressor Development Reference Design (RCDRD) is intended to aid

the engineers to develop the PMSM compressor control application with dsPIC® Digital

Signal Controllers (DSCs). This development Ref Design is targeted to provide a

competitive sensor-less control solution applies to both Interior Permanent Magnet

Synchronous Motor (IPMSM) and Surface Permanent Magnet Synchronous Motor

(SPMSM) compressor. Both hardware and software are provided.

The rated continuous output current is 0.65A (RMS). This allows up to approximately 250W

continuous output power when running from a 187V to 264V single-phase input voltage in

room temperature environment. The peak output power is 350W for instantaneous high

compressor pressure operation. More details of the RCDRD hardware is provided in

Chapter 2 “Hardware Description”.

This document describes how to use RCDRD prototype 1. Below Fig 1-1 gives the picture

of this Reference Design.

Fig 1-1 Refrigerator Compressor Development Reference Design



1.1 System and Tools Requirements

1.1.1 Basic requirements

• Refrigerator Compressor Development Board (RCDB).

• MPLAB X V5.10 or later.

• Compiler XC16 V1.33 or later.

• PICkit™ 3 / PICkit™ 4 In-Circuit Debugger (Part Number: PG164130 / PG164140)

1.1.2 Advanced requirements

Below requirements are used for Diagnostic and Test-Harness function.

• MCP2200 Isolated USB to UART Demo Board (Part Number: ADM00276)

• 4 pcs Dupont line.

• X2C Scope plugin V1.30.



2 Hardware Description

2.1 Introduction

The RCDB is powered from 220V AC grid and controls the compressor motor with

dsPIC33EP64MC202. The input 220V AC voltage is passed through the Filter & protection

circuitry, and then converted to DC voltage by rectifier circuitry. An auxiliary power supply

circuitry supplies non-isolated 15V and 3.3V voltage to MCU, feedback circuitry and three

phases inverter bridge circuitry. Below Fig 2-1 gives the picture of the board while Fig 2-2

shows the block diagram.

Fig 2-1 Refrigerator Compressor Development Board



Fridge Compressor Development Board

Filter &

Protection

220V AC

input

Motor control

output

Rectifier

DC BUS

Feedback

circuitry

15V Power

Supply3.3V

Power

Supper

UART 1 Programming

port

Square

wave input

UART 2

MCU circuitry

Inverter circuitry

22

0V

AC M

oto

r

Iso

late

d

UA

RT

-US

B

PIC

kit™

3

/ PIC

kit™

4

Square

wave

Communic-

ation

Fig 2-2 RCDB block diagram

2.2 Key Functional Modules

The RCDB has various functional modules which implement its salient features: EMI filter

& protection, Rectifier, Auxiliary power supply, MCU, Inverter, Feedback circuitry, and

Communication ports. They are marked in the Figure 2-3 and Tab 2-1.



1

2 3 4

56

7

Fig 2-3 RCDB functional modules

Tab 2-1 RCDB functional modules

① EMI filter & Protection ⑤ Three phase inverter bridge circuitry

② Rectifier ⑥ Feedback circuitry

③ Auxiliary power supply ⑦ Communication ports

④ MCU

2.2.1 EMI filter and Protection

The input power of the board is passed through the EMI filter & Protection module firstly,

as Fig 2-4 below. The F300 is a 250VAC/10A fast-acting fuse whose opening time is 0.03s

at 1000% of its ampere rating. The Vst300 is a zinc oxide varistor named TVR14561D for



surge protection. The EMI filter has two-stages. If only one-stage filter is valid, the CY300,

CY303, CX302, L301 and CX300 should be unsoldered and L301 should be shortened.

AC InputAC Output

Fig 2-4 EMI filter and Protection circuitry

2.2.2 Rectifier

This module includes an in-rush current protection, a single-phase full-bridge rectifier and

a DC bus capacitor, as Fig 2-5 below. The in-rush current was suppressed by a power

resistor R305 at the moment of powering on the board. After the DC bus capacitor is full

charged, the power resistor is shortened by relay RL30. The single-phase bridge rectifier

DB300 converts the input alternating voltage at power frequency into constant DC voltage.

VAC VBus

Fig 2-5 Rectifier circuitry

2.2.3 Auxiliary power supply

The Auxiliary power supply is to generate 15V and 3.3V for IGBT driver and

dsPIC33EP64MC202 separately.



The block diagram of auxiliary power supply is shown in Fig 2-6. The 15V power rail is

stepped down directly from the rectifier output. This eliminates the transformer and high

voltage rate components used in a Flyback approach. A MCP16331 is used to step down

this 15V to 5V.. The MIC5239 LDO regulates the 3.3V from 5V voltage to provide the

control chip dsPIC33EP64MC202 with a clean power supply. Besides the control chip, this

3.3V rail is also to power other digital and analog control circuitry, such as ADC reference,

feedback circuitry. This approach provides nice auxiliary power supply with small power

consumption.

VBus–15V

Buck Circuit

by VIPER12A

15V–5V

DC-DC circuit

by MCP16331

5V–3.3V

LDO circuit

by MIC5239

VBus 15V

5V 3.3V

IGBT Driver

MCU

Feedback

ADC reference

Fig 2-6 Auxiliary power supply

The details of all these three auxiliary circuit is shown in Appendix B. Schematic Diagram.

2.2.4 MCU

A dsPIC33EP64MC202 is selected in this design. There is also an approach that a single

chip conducts both refrigerator system control and compressor control job. Microchip

provides many other products in dsPIC33EP or dsPIC33CK series can well meet the

application.

In this design, the chip pinout functionality is listed in table below.

Tab 2-2 dsPIC33EP64MC202 pinout functionality (SSOP)

Pin

No. Pin Functions

Active

Function Description I/O ANSEL PPS

1 MCLR MCLR RESET

2 AN0/OA2OUT/RA0 OA2OUT IOUT 1

3 AN1/C2IN1+/RA1 C2IN1+ I+ 1

4 PGED3/VREF-/AN2/C2IN1-

/SS1/RPI32/CTED2/RB0 C2IN1- I- 1

5 PGEC3/VREF+/AN3/OA1OUT/R

PI33/CTED1/RB1 AN3 VBUS I 1

6 PGEC1/AN4/C1IN1+/RPI34/RB2 RPI34 RX1 I 1

7 PGED1/AN5/C1IN1-/RP35/RB3 RP35 TX1 O 1

8 VSS VSS VSS

9 OSC1/CLKI/RA2 RA2 LED1 O

10 OSC2/CLKO/RA3 RA3 Clock out / test

point I/O

11 FLT32/RP36/RB4 RB4 test point I/O

12 CVREF2O/RP20/T1CK/RA4 RA4 Relay O



13 VDD VDD VDD

14 PGED2/ASDA2/RP37/RB5 PGED2 Debug I

15 PGEC2/ASCL2/RP38/RB6 PGEC2 Debug I

16 SCK1/RP39/INT0/RB7 RP39 RX2 I 1

17 TCK/CVREF1O/ASCL1/SDO1/R

P40/T4CK/RB8 RP40 TX2 O 1

18 TMS/ASDA1/SDI1/RP41/RB9 PR41 Square_INPUT I 1

19 VSS VSS VSS

20 VCAP VCAP VCAP

21 TDO/RP42/PWM3H/RB10 PWM3H PWM3H O

22 TDI/RP43/PWM3L/RB11 PWM3L PWM3L O

23 RPI44/PWM2H/RB12 PWM2H PWM2H O

24 RPI45/PWM2L/CTPLS/RB13 PWM2L PWM2L O

25 RPI46/PWM1H/T3CK/RB14 PWM1H PWM1H O

26 RPI47/PWM1L/T5CK/RB15 PWM1L PWM1L O

27 AVSS AVSS AVSS

28 AVDD AVDD AVDD

2.2.5 Inverter circuitry

Discrete IGBTs and single shunt current sample are employed in the three-phases inverter

to save system cost. It consists of:

• 6 pcs 600V/15A IGBT

• 3 pcs 600V Half Bridge IGBT Driver MIC4608

• Single Shunt resistor for motor phase current sensing

• PWM switching frequency is 2.5 kHz

The MCU provides the PWM signals to the 3 half bridge drivers switching the 6 IGBTs, and

therefore apply power to the motor phases. Single shunt is connected in series on negative

DC bus for current feedback and over-current protection.

For simplicity, one of the 3 phase inverter circuit is shown in Fig 2-7.

15V VBus

PWMuH

PWMuLUu

VDD

HI

LI

HB

HO

LO

HS

VSS

MIC4608

DBST

RBST

CBST

DCLAMP

Figure 2-7 One phase inverter bridge circuitry diagram



Bootstrap Circuit

The high-side driver of MIC4608 is designed to drive a floating N-channel IGBT, whose

source terminal is referenced to the HS pin. A level-shifting circuit in MIC 4608 isolates the

low-side (VSS pin) referenced circuitry from the high-side (HS pin) referenced driver.

Power to the high-side driver is supplied by the bootstrap capacitor (CBST) while the voltage

level of the HS pin is shifted high.

HS Node Clamp

A diode clamp between the switching node and the HS pin is recommended to minimize

large negative glitches or pulses on the HS pin.

More detail of the bootstrap circuit and HS node clamp can be found in MIC4608 datasheet.

2.2.6 Feedback circuitry

DC bus voltage and motor phase current are sampled for motor control and protection.

• DC Bus Voltage Feedback. It is compounded by a voltage divider and a low-pass

RC filter. The divider divides the DC bus voltage to 3.3/443.3V in order to match the

MCU logic levels.

• Motor current feedback. A shunt resistor is located between the emitter of the three

low side switches and the “DC-”. dsPIC33EP64MC202 provides internal operational

amplifiers (Op-Amp) and comparators. They are used for amplifying motor current

and over-current protection. The gain of the Op-Amp is set to 4, the shunt resistor

voltage signal is shifted by 0.2VDC. Hence the motor phase current ranges from -

4.125A to +4.125A.

The location of the feedback circuit is shown in Fig 2-8.

VBus

440K

3.3K

Sample Shunt

100m

C2INI+

C2INI-

3.3V

3

4

2

ADC / Comparator

ADC5 AN3

dsPIC33EP64MC202

2K

2K

133K

8.66K

8.06K

DC Bus Voltage Feedback

Motor Current Feedback

Fig 2-8 Feedback circuitry diagram



2.2.7 Communication ports

The RCDB provides three ports for transmitting/receiving data to and from debug tools

and/or system control board. All these ports are powered by 3.3V rail.

• UART1 communication port is non-isolated. It translates the UART signals directly

to and from dsPIC® DSC on board. This port is used to communicate with

laptop/MPLAB X IDE.

Note: The UART1 port is NON-ISOLATED. There is a big risk to damage the

board when connecting this port directly with other non-isolated system. It’s

strongly suggested connecting this port with MCP2200 Isolated USB-UART

Demo Board or other isolated USB-UART converters.

• UART2 communication port is used to communicate with refrigerator system control

board for commands and operation-status information. This port is isolated by two

optocoupler.

• Square wave acceptor port provides another method to receive speed command

from main control board. This port is isolated by a phototransistor.

The communication ports location is shown in Fig 2-9.

UART1

Square wave acceptor UART2

Fig 2-9 Communication ports

2.3 User Interface

2.3.1 Connectors and Sockets

(1) Power Sockets

• AC power inlet (CON300)

• Three-phase inverter connector to compressor (CON100)

(2) Signal sockets

• Isolated square wave receiver socket (CON200)

• Isolated UART2 communication socket (CON201)

• Non-isolated UART1 communication socket (CON202)

• PICkit™ 3 / PICkit™ 4 In-Circuit Debugger socket (CON203)

UART sockets have 4 terminals. Square wave socket has 2 terminals. Debugger socket

has 5 terminals. Table 2-3 shows the functionality of each terminal.



Tab 2-3 Terminal functionality of signal sockets

Socket

Num

Socket name

Pin Terminal functionality

SON200 Isolated square wave

acceptor

1 +

2 Isolated GND

CON201 Isolated UART2

1 Isolated VCC

2 TXD2

3 RXD2

4 Isolated GND

CON202 Non-isolated UART1

1 3.3V

2 GND

3 RXD1

4 TXD1

CON203

PICkit™ 3 / PICkit™ 4

In-Circuit Debugger

socket

1 MCLR

2 3.3V

3 GND

4 PGD

5 PGC

All the sockets location can be found in Fig 2-10.

CON

200

CON

201

CON202

CON203

CON300 CON100

22

0V

AC

Co

mp

resso

r

Square

wave

UART

communication

LD300

LD200

PIC

kit™

3

PIC

kit™

4

Iso

late

d

UA

RT

-US

B

Fig 2-10 All sockets and LED indicators



2.3.2 LED indicators

There are two LED indicators in the development board. The two LED location can be

found in Fig 2-10 above.

LD300 indicates whether 3.3V power rail is available. This LED is lighted when 3.3V power

rail is ready.

LD200 indicates the board operation status and error message. The LED blinks all the time

after the board is powered. Customers could get the operating information via LED blinking.

When RCDB is operating as expected, say runs the compressor, below table shows all its

possible operation status.

Tab 2-4 Operation status LED blink pattern

System states LED blink pattern

RESTART Off

STARTING 15/16 on @ 0.625Hz

RUNNING 1/16 on @ 0.625Hz

STOPPING 15/16 on @ 0.625Hz

STOPPED 50% on @ 0.625Hz

If the board driving the compressor was in fault state, the LED will blink as in below error

code

Tab 2-5 Error codes LED blink pattern

Fault types LED blink pattern

Traps

ERR_OSC_FAIL + + - - -

ERR_ADDRESS_ERROR + + + - - -

ERR_HARD_TRAP + + + + - - -

ERR_STACK_ERROR + - + + - - -

ERR_MATH + + - + + - - -

ERR_RESERVED_TRAP5 + + + - + + - - -

ERR_SOFT_TRAP + + + + - + + - - -

ERR_RESERVED_TRAP7 + - + + + - - -

Application errors

ERR_STALL + - + - + + - - -

ERR_INVALID_STARTUP_FSM_STATE + + - + - + + - - -

ERR_HW_OVERCURRENT + + + - + - + + - - -

ERR_DCLINK_OVERVOLTAGE + + + + - + - + + - - -

ERR_DCLINK_UNDERVOLTAGE + - + + - + + - - -

ERR_DIRECTREVERSE + + - + + - + + - - -

ERR_SPEEDERROR + + + - + + - + + - - -

Reset errors

ERR_RCON_TRAPR + - + - + + + - - -



ERR_RCON_IOPUWR + + - + - + + + - - -

ERR_RCON_CM + + + - + - + + + - - -

ERR_RCON_WDTO_ISR + + + + - + - + + + - - -

ERR_RCON_WDTO_MAINLOOP + - + + - + + + - - -

ERR_UNEXPECTED_INTERRUPT_BASE + - + - + - + - + + - - -

In the tab above, a “+” represents LED blinking once with 50% duty @ 1.67Hz. A “-”

represents LED tuning off in the whole cycle of 1.67Hz.

2.4 Electrical Specifications

The electrical specifications of the RCDB board is in table below:

Tab 2-6 Electrical Specifications of RCDB board

No. Parameters Spec

1 Rated Input Voltage 220VAC 50/60Hz

2 Input Voltage range 90V~264V AC

3 Digital Voltage 3.3V

4 Rated Power 250W

5 Maximum Power 250W

6 PWM Frequency range 2.5kHz~15kHz

7 Operating Temperature -10℃ ~ +60℃

8 Board Efficiency 94%

9 Board Standby Power 0.5W

10 Board Size 130mm × 120mm × 40mm

11 Rectifier Y

12 Auxiliary Power Supply Y

13 PFC Circuitry N

14 Power Circuitry Discrete

15 Current Sensing Single Shunt, Internal Op-Amp in dsPIC®

16 DC Bus Voltage Sensing Y, Internal Op-Amp in dsPIC®

17 Temperature Sensing N

18 Hardware Over-Current Protection Y, Internal comparator in dsPIC®

19 In-rush current protection for DC bus Y, Power resistance and Relay



3 Setup and Run

The software of RCDRD is configured for Basic Operation. This chapter describes how to

setup the software, run the compressor and debug the code.

3.1 Basic Operation

Basic operation is to open the S/W project, configure and build the code and program the

chip on development board.

(1) Start MPLAB X IDE V5.10 and open the project “RCDRD_V1.0.X”.

Note: The project requires MPLAB X IDE V5.10 or later.

(2) Right click on this project on the left tab named “Project”, and select the last item

“Properties”.

On the “Project Properties” page you can select the programmer/debugger in

“hardware tool” section and select compiler (XC16 V1.33 or later) in “Compiler

toolchain” section. The “PICkit 3”/“PICkit 4” term can be found in Hardware Tools list



after connecting the Programmer/Debugger to laptop. Click “Apply” to apply the

selection.

(3) The RCDB board is a hot-ground design. It is prohibited to be powered when connects

with any other non-isolated tools and equipment, such as computer, laptop,

oscilloscope, etc. Programmer/Debugger is suggested to program the chip as it can

provide 3.3V to the board for programming.

After applying Programmer/Debugger selection (PICkit 3/PICkit 4), the “PICkit

3”/“PICkit 4” term can be found in “Categories” list in “Project Properties” window.

On “PICkit 3”/“PICkit 4” page, select “Power” item in “Option categories”. Check

“Power target circuit from PICkit3” item and select “3.25” on “Voltage level” item. Click

“OK” to apply the selection.



(4) Build the code by clicking the “Clean and Build Project” button on the toolbar or in the

“Production” menu.

or

(5) After a successful build, connect PICkit 3/PICkit 4 to RCDB CON203.

Download code to the chip by clicking “Make and Program” button on toolbar



Note: Before this step, make sure that the AC power supply is DISCONNECTED

to the board.

(6) Disconnect the PICkit3 with the board. Make sure RCDB is not connected with any

other non-isolated board or equipment.

(7) Connect a compressor or a motor on CON 100, connect the AC power supply on

CON300. Power on the development board. The board now is in STOPPED status, the

LED blinks 50% on @ 0.625Hz.

3.2 Run with Diagnostic Kernel

In terms of RCDRD prototype 1, the only way to run the compressor is by Diagnostic Kernel

function in code. The tool working with Diagnostic Kernel function is X2C Scope plugin and

MCP2200 Isolated USB to UART Demo Board. The X2C Scope is a plugin of MPLAB X

IDE to facilitate the debug job. It provides a complete feature to read and write variables in

dsPIC®’s data memory by means of UART. Furtherly it can plot those variables in a real

time mode.



(1) Install X2C Scope plugin. Select “Plugins” item from “Tools” menu. On “downloaded”

page, click “Add Plugins…” button, select “at-lcm-x2c-mplabscope.nbm” file. Click

“Install” to install X2C Scope plugin.

(2) Open the project properties (as in 3.1(2)) and enable “Load symbols when

programming or building for production (slows process)” during production builds in

“Loading” page.

(3) Connect the MCP2200 Isolated USB to UART Demo Board to computer and RCDB

by Dupont lines.



(4) Download the code to the driver board (as described in 3.1(4)(5)(6)), disconnect all

non-isolated devices.

Note: The code needs to be downloaded every time the board was power off and

on for connecting X2C Scope to MCU on board.

(5) Disconnect the Programmer/Debugger and power on the board

(6) Start X2C Scope by clicking “X2CScope” from “Embedded” on “Tools” menu. The

“X2C Scope Configuration” window will open.



(7) Set the parameters as picture below, select this RCDRD project in “Select Project”

button. Then click “Disconne…” button to connect computer to driver board.

Parameters setting

(8) On “Project Setup” page, “Scope Sampletime” configures the sample interval to

display in scopes time-axis. It must be the same value as the PWM cycle. In RCDRD,

it is 400 us (2.5kHz). The “watch sampletime” configures the refresh interval in the

“X2C Scope Watch” window. It should be bigger than PWM cycle. Click “Set Values”

to apply the setting.



(9) On “Data Views” page, click “Open Scope View” to open “X2C Scope Scope” window.

This window displays the wave form of variables. Click “Open Watch View” to open

“X2C Scope Watch” window. Variables value is displayed and changed in this window.

Only global variables can be added in these two windows.



For example, in below figure, three variables systemData.X2CVelocityReference,

systemData.X2CSystemStatesFlag and motor.faultDetect.faultDetectFlagBackup are

selected in “X2C Scope Watch” window. Variable systemData.X2CVelocityReference

is the reference electromagnetic speed of compressor motor, in the unit of RPM.

Variable systemData.X2CSystemStatesFlag is the system status flag. Variable

motor.faultDetect.faultDetectFlagBackup is the fault flag. More detail flag information

is description in Appendix A. Flag Description. You can add other variables you are

interested in.

(10) Add the variables which you want to observe in “X2C Scope Scope” window. For

example, add the reference velocity and feedback velocity, reference id/iq and

detected id/iq, output vd/vq, etc. Click the “SAMPLE” button to start sampling variables

and show the waves.



(11) Configure reference speed variable systemData.X2CVelocityReference with a data

bigger than minimum speed. The compressor will start to run. Scope Window will show

the variable waveforms in real time.

Watch window

Scope window

(11) At the end of the operation, remember to click “Connected” button to disconnect X2C

Scope to board.

(12) More detail of X2C Scope is described in file “X2CScope Documentation”.

3.3 Debug and Test by Test Harness

In FDCRD, there is a Test Harness component which provides an easy method to modify

the control operation mode of the commutation and motor control loops. It represents

several runtime parameters which are used to put the system into certain test modes. In



combination with other adjustable parameters used in motor control application, we can

debug and test proper operation of the compressor and board. it is tightly coupled to

commutation and motor control loops, as picture below.

FOC

Velocity PI

controller

iq*Uq* In

v P

ark

Usa*

Usb*

Usc*

M

Ud*id*

isa

isb

isciq

id

r

e

*e Current PI

controler

*U

*U

-

--

SV

PW

M i

n

single

shunt

PWM

Duty

cycle

Current PI

controler

Inv C

lark

e

Single shunt

process

Current

sampleCla

rke

Par

k

i

i

Trigonometric

calculation

sin, cos

(2) Set Vd/Vq(3) Set id/iq(4) Set ωe

(5) Set fedt

d

(6) Set θ

3.3.1 Debug and test operation by Test Harness

All the debug and test operation is set in “X2C Scope Watch” window.

(1) Start test mode

Set the key will run the control system into test mode. Otherwise, all other Test

Harness features are unavailable.

Start operation:

Set systemData.testing.key = TEST_GUARD_VALID = 53670.

Stop operation:

Set systemData.testing.key != TEST_GUARD_VALID != 53670.

(2) Set Vd and Vq directly

Bypass velocity loop and current loop and feed their output Vd/Vq with a setting value.

It is used to debug and test the SVPWM duty calculation function. This function only

sets the amplitude of the output voltage.

Start operation:

Set motor.testing.overrideVdqCmd.d and motor.testing.overrideVdqCmd.q with

proper data. The values of these two variables are normalized.

Set motor.testing.operatingMode = OM_FORCE_VOLTAGE_DQ = 1. The setting

Vd and Vq are available.

Stop operation:

Set motor.testing.operatingMode = OM_DISABLED = 0. There is no output

voltage.

Related function:



In combination with electromagnetic frequency in Feature (5) to set the output

voltage frequency.

In combination with electromagnetic angle in Feature (6) to set the output voltage

of motor phase.

(3) Set idCmd and iqCmd directly

Bypass velocity loop and enable current loop and feed current reference id/iq with a

setting value directly. It can be used to debug and test current loop, tune PI parameters,

calibrate current sample, etc. This function only sets the amplitude of the output current.

Start operation:

Set motor.testing.overrideIdqCmd.d and motor.testing.overrideIdqCmd.q with a

proper data. Attention that the values of these two variables are normalized.

Set motor.testing.operatingMode = OM_FORCE_VOLTAGE_DQ = 2. Then the Id

and Iq will output as we set.

Stop operation:

Set motor.testing.operatingMode = OM_DISABLED = 0. There is no output

current.

Related function:

In combination with electromagnetic frequency in Feature (5) to set the output

current frequency.

In combination with electromagnetic angle in Feature (6) to set the output current

of motor phase.

(4) Set reference speed directly

Set the speed command reference directly in FOC operation, ignore original speed

command. It is used to debug and test the velocity loop and tune PI parameters.

Start operation:

Set motor.testing.operatingMode = OM_NORMAL = 3.

Set motor.testing.overrideOmegaElectrical with proper data. Attention that the

variable is electromagnetic speed, unit is RPM.

Set motor.testing.overrides = TEST_OVERRIDE_VELOCITY_COMMAND = 1.

Start system. After startup period, the driver will spin the motor at the setting

reference speed.

Stop operation:

Set motor.testing.overrides = 0. The original speed order is available.

(5) Set electromagnetic frequency directly

Set the electromagnetic frequency directly in commutation component, ignore the

estimated theta. Cooperate this feature with Feature (2) / Feature (3), the frequency

of output voltage / current can be set. If setting the frequency to 0, the output voltage

/ current is DC.

Start operation:

Set motor.testing.overrideCommutationFrequency with proper data. Attention that

the variable is electromagnetic frequency of FOC, unit is Hz.

Set motor.testing.overrides = TEST_OVERRIDE_COMMUTATION = 2.

Set Feature (2) or Feature (3).

Stop operation:



Set motor.testing.overrides = 0. The estimated frequency is available. Attention

that there is still output voltage or current which is set by Feature (2) or Feature

(3).

(6) Set electromagnetic theta

Set the electromagnetic theta directly in commutation component, ignore the estimated

theta. Cooperate this feature with feature (2) / feature (3), motor phase voltage / current

will be controlled to the setting value.

Start operation:

Set motor.testing.overrideThetaElectrical with proper data. Attention that the

variable is electromagnetic theta of FOC, unit is normalized.

Set motor.testing.overrides = TEST_OVERRIDE_COMMUTATION = 4

Set Feature (2) or Feature (3).

Stop operation:

Set motor.testing.overrides = 0. The estimated theta is available. Attention that

there is still output voltage or current which is set by Feature (2) or Feature (3).

(7) Time stamps

An array of 16-bit timestamps is part of the test harness state structure. These

timestamps are recorded in various places for profiling the main control process via

real-time diagnostic tools. The time stamp uses Timer 1 which runs at the system clock

rate (Fcy = 70MHz), so that the timer value indicates the elapsed system clock time.

Description of Time stamps array variables:

motor.testing.timestamps[0]: The executing time before state machine start

motor.testing.timestamps[1]: The executing time of performing all critical tasks

that are independent of the state.

motor.testing.timestamps[2]: The executing time of determining next state.

motor.testing.timestamps[3]: The executing time of updating state and executing

appropriate actions in the state.

motor.testing.timestamps[4]: The executing time of performing all noncritical tasks

that are independent of the state.

motor.testing.timestamps[7]: The executing time of other process, including UI,

Monitor, Watchdog, etc.

Operation:

Add the timestamps array variables in X2C Scope.

3.3.2 Brief summary of the Test Harness setting

Conclude the Test Harness features and setting on the table below:

Tab 3-1 Brief summary of the Test Harness features and setting

Setting

Features

on-off Parameter setting Control Setting

system

Data.te

sting.k

ey

motor.t

esting.

overrid

eVdqC

md.d

motor.t

esting.

overrid

eVdqC

md.q

motor.t

esting.

overrid

eIdqC

md.d

motor.t

esting.

overrid

eIdqC

md.q

motor.tes

ting.overr

ideOmeg

aElectric

al

motor.tes

ting.overr

ideComm

utationFr

equency

motor.tes

ting.overr

ideTheta

Electrical

motor.t

esting.

operati

ngMod

e

motor.t

esting.

overrid

es

Set Vd and Vq 53670 value value —— —— —— —— —— 1 ——



Set Id and Iq 53670 —— —— value value —— —— —— 2 ——

Set speed 53670 —— —— —— —— value —— —— 3 1

Set frequency 53670 value value value value —— value —— 1/2 2

Set angle 53670 value value value value —— —— value 1/2 4

Disable !53670 —— —— —— —— —— —— —— —— ——



4 Run a Different Compressor

Motor control is a very motor and application dependency system. Compressor motor

control brings even more challenge in reliable startup and unbalanced load in every

mechanism revolution. RCDRD is targeted to provide an easy way to run with different part

number compressor. This chapter describes how to use RCDRD to run a compressor other

than the developers were using for debug and test.

To run a different compressor, some parameters need a modification to fit with the

compressor. All code files need to be modified are the header files in folder “parameters”

besides one C source file “opamp_comparator.c” in folder “hal”.

4.1 Modify theoretical arithmetic parameters

(1) Because dsPIC® is a fixed-point controller, the motor parameters cannot be used

straightly in code since they are fractional data. Therefore, we must convert the

physical units to fixed point PU format (mostly Q15). “tuning_params.xlsx” is provided

to implement this conversion. There are many parameters in the “tuning_params.xlsx”

file, which are described as below.

Tab 4-1 Parameter types in “tuning_params.xlsx”

Kinds Property Marks

Input Physical units of H/W board parameters.

Input Physical units of motor parameters.



Output Board and motor parameters in fixed-point

format. Constant to set in "xxxx_parms.h".

Output Startup algorithm parameters in fixed-point

format. Constant to set in "startup_params.h".

others Interim calculation data.

In order to get the fixed-point parameters, the motor parameters should be input in

“tuning_params.xlsx” as below.

The fixed-point format value is then be generated in the purple background cells. To

avoid saturation, resolution loss and truncation error caused by Q15 implementation,

it is recommended that the fixed-point data should be in the range of 6000-26000. If

the fixed-point data falls out of the recommended range (greater than 26000), the scale

“Q” should be adjusted to achieve the recommended range.

(2) Modify over-current threshold in register CVR (CVRCON<3:0>) in C source file

“hal/opamp_comparator.c”.

(3) Modify the parameters of estimator Angle Tracking Phase-Locked Loop (ATPLL) in

header file “parameters/atpll_params.h”.



(4) Modify software over-current threshold value of stall detection in header file

“parameters/fault_detect_params.h”.

(5) Modify motor parameters in header file “parameters/motor_params.h”.

(6) Modify parameters of Maximum Torque Per Ampere (MTPA) algorithm in header file

“parameters/mtpa_params.h”.

(7) Modify motor speed parameters in header file “parameters/operating_params.h”.



(8) Modify PI saturation threshold of velocity loop in header file

“parameters/sat_PI_params.h”.

(9) Modify parameters of startup algorithm in header file “parameters/startup_params.h”.

(10) Go back to Chapter 3 “Setup and Run” to program and run the code.

4.2 Debug parameters

4.2.1 Debug startup parameters

The startup algorithm in RCDRD is specialized for compressor application. It not only

improves the startup reliability, but also reduce vibration. All the startup algorithm

parameters are in header file “parameters/startup_params.h”. Some of them need to be

debugged when changing a compressor.

Refer to the Tab 4-2, in “Startup algorithm parameters” section of “tuning_params.xlsx”,

column “value” is the theoretical calculated value, the column “normalization” is the

normalized value. The column “revise” is the debugged value, the column “revise

normalization” is the normalized debugged value.

Tab 4-2 “Startup algorithm parameters” section of “tuning_params.xlsx”



Theoretical value

Debugged value

Normalized theoretical value

Normalized debugged value

Only a few parameters in the table above need fine-tuning when changing a compressor.

They are described as below.

Tab 4-3 Key parameters for startup

Parameters Description Debugging

STARTUP_FINALTOR

QUE Open loop current Increase it if startup load was big

STARTUP_ACCELER

ATION0

Acceleration of the first velocity

accelerating state

Increase it if shorter startup time.is

wanted

STARTUP_ACCELER

ATION1

Acceleration of the second velocity

accelerating state

Increase it if shorter startup time.is

wanted

STARTUP_RAMPDO

WN_END_CURRENT

The current threshold for switching

open loop to close loop

This parameter is always equal to open

loop current in compressor application

4.2.2 Debug PI parameters

The PI controller parameters of current loop and velocity loop may need tuning when

changing compressor. All the PI parameters are in header file “parameters/for_params.h”.



The Kxx_Q (KIP_Q, KII_Q, KWP_Q and KWI_Q) is the scaler. Kp and Ki is multiplied by

2^Kxx_Q to get final PI controller data used in code. During the very early stage of the

debug job, changing this scaler value rather than Kp (Ki) will help reducing the debug time

to find a rough Kp (Ki) value.



5 Known Issues

(1) Computer can’t connect to RCDB with X2C Scope.

Several causes may lead this issue.

• Scenery 1: Open a new project in MPLAB X without disconnecting X2C Scope.

Work Around: Restart the MPLAB X and redownload the program to the board.

• Scenery 2: Sometimes the chip might fall in watchdog overtime protection. It

could be caused by some mistake when modifying the code. Check LED (LD200)

blink to get the chip operation status.

Work Around: Power off the RCDB. Re-connect the UART1 port and power on

the board.



Appendix A. Flag Description

All state flags of RCDRD are described in below tables.

Tab A-1 System state

System State

Variable motor.state

Flag enum

0 MCSM_RESTART

1 MCSM_STOPPED

2 MCSM_STARTING

3 MCSM_RUNNING

4 MCSM_STOPPING

5 MCSM_FAULT

6 MCSM_TEST_DISABLE

7 MCSM_TEST_ENABLE

Tab A-2 Error code

Error code

Variable motor.faultDetect.faultDetectFlagBackup

Flag Enum

1 OVERVOLTAGE

2 UNDERVOLTAGE

4 OVERCURRENT

8 DIRECTREVERSE

16 SPEEDERROR

32 STALL

Tab A-3 Stall detecting code

Stall code

Variable motor.stallDetect.stallDetectFlagBackup

Flag Enum

1 OVERCURRENT

2 LOSS_OF_LOCK

4 LOW_SPEED

8 TORQUE_ANGLE



Appendix B. Schematics

refrigerator compressor reference design user guide

Documents