drives lecture 1
TRANSCRIPT
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Chapter 1. Introduction
Design of
Electronic Drivesfor AC Machines
Dr. Umar T. Shami
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Introduction
Text Book
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1.1 The need for Variable speed drives
1.2 Fundamental Principles
1.4 Types of Variable Speed Drives
1.8.4 Electrical variable speed drives forDC motors (DC drives)
1.8.5 Electrical variable speed drives
for AC motors (AC drives)
2.1 The 3-Phase Induction Motor
Chapter 1 Introduction
CONTENTS
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1.1 The need for Variable speed drives
In general, variable speed drives are used to:
Match the speed of a drive to the process requirements Match the torque of a drive to the process requirements Save energy and improve efficiency
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The following is a review of some of the fundamental principles
associated with variable speed drive applications.
1.2 Fundamental principles
Forward direction
Forward direction refers to motion in one particular direction.
The Forward direction is designated as being positive (+ve).
Reverse direction
Reverse direction refers to motion in the opposite direction. The
Reverse direction is designated as being negative (ve).
Force
Motion is the result of applying one or more forces to an object.
Motion takes place in the direction in which the resultant force is
applied. So force is a combination of both magnitude and direction.
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1.2 Fundamental principles
Linear velocity (v) or speed (n)
Linear velocity is the measure of the linear distance that a movingobject covers in a unit of time.
In SI units, this is usually measured in meters per second (m/sec).
Kilometers per hour (km/hr)
Angular velocity () or rotational speed (n)
Although a force is directional and results in linear motion, many
industrial applications are based on rotary motion.
TorqueThe force used for rotating is known as torque.
In SI units, torque is measured in Newton-meters (Nm).
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TorqueThe force used for rotating is known as torque.
In SI units, torque is measured in Newton-meters (Nm). Linear acceleration (a)
Linear acceleration is the rate of change of linear velocity, usually in
m/sec2.
1.2 Fundamental principles
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Rotational acceleration (a)
Rotational acceleration is the rate of change of rotational velocity,usually in rad/sec2.
PowerPower is the rate at which work is being done by a machine. In SI
units, it is measured in watts.
1.2 Fundamental principles
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Energy
Energy is the product of power and time. In SI units it is usuallymeasured as kiloWatthours (kWh).
1.2 Fundamental principles
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1.4 Types of Variable Speed Drives
(a) Typical mechanical VSD with an AC motor as the prime mover
(b) Typical electrical VSD with a DC motor and DC voltage converter;
(c) Typical electrical VSD with an AC motor and AC frequency
converter;
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1.8 Electrical Variable Speed Drive Methods
1.8.2 Ward-Leonard system
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The fundamental principles of a DC variable speed drive
1.8 Electrical Variable Speed Drive Methods
1.8.3 Electrical Variable Speed Drive For DC Motors
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1.8 Electrical Variable Speed Drive Methods
1.8.4 Electrical Variable Speed Drive For AC Motors
This is what we will study in detail (InshaALLAH).
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Chapter-2Three-Phase AC Induction Motors
The Induction Motor was invented by Nikola Tesla In 1888.
Nikola TeslaThe early induction motor
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The AC induction motor consist of :
Stationary part called the stator
Chapter-2Three-Phase AC Induction Motors
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Rotating part called the rotor,supported at each end on
bearings
Chapter-2Three-Phase AC Induction Motors
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2.2.1 The stator
The stator is the outer stationary part of the motor, which consists
of: The outer cylindrical frame of the motor,
The magnetic path,
A set of insulated electrical windings.
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2.2.1 The rotor
This is the rotating part of the motor. The rotor can be either:
Wound rotor type,
Squirrel cage rotor type
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The stator and rotor
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