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UNIT I: DRIVE CHARACTERISTICS
Characteristics of mechanical system; requirement of drive
characteristics; selecting the drive elements; modeling of dc
motor; selection of motor rating; P. PI and PID controllers;
constant HP and constant torque operations.
UNIT II: DC DRIVES
Single phase and three phase drives - half controlled and
fully controlled; Chopper drives - class A, B, C, D and E
chopper drives; braking of dc drives.
UNIT III: STATOR SIDE CONTROLLED INDUCTION MOTOR
DRIVE
Stator voltage controlled induction motor drive - slip torque
characteristics; different configuration of controller's input
current; closed loop operation.
Stator frequency controlled induction motor drive-Slip-
torque characteristics; harmonic equivalent circuit; Rotating
magnetic fields; harmonic current; efficiency; torque;
stability.

UNIT IV: ROTOR SIDE CONTROLLED INDUCTION MOTOR
DRIVE
Rotor Resistance Control: slip-torque characteristics;
equivalent chopper resistance; chopper circuit filter;
constant current operation.
Slip Power Recovery Scheme: Slip power recovery scheme;
sub synchronous operation; performance prediction;
input power factor.
UNIT V: SYNCHRONOUS MOTOR DRIVES
Open loop volts/hertz control and self-control of
synchronous motor: Marginal angle control and power
factor control. Introduction to vector control - Principles
and types.

 This course will make an engineering student to
 Understand the performance of electric drives controlled
from power electronic converters.
 Will come across characteristics, modeling and selection of
motor power rating.
 To understand the operation and performance of converter
and chopper fed dc drives.
 Teaches solid state control of induction motors both from
stator side and rotor side and closed loop operation of
electric drives and
 Teaches various control techniques for synchronous motor
drives.

On successful completion of the course, student will be able to
CO1
 Familiarize with the electrical and mechanical limitations, operating
regions and selection of drives.
CO2
 Analyze the performance of converter/chopper fed drives and application
of power electronics for controlling the motors in different modes.
CO3
 Analyze the various speed control methods of stator side controlled
Induction motor drives and applications like Textile mills, Paper mills.
CO4
 Analyze the various speed control methods of rotor side controlled
Induction motor drives and efficient energy recovery techniques for
Electric Traction, Electric vehicle drive systems.
CO5
 Analyze the different types of control in Synchronous motor drives and its
application in paper processing, marine, cement industries.

Electrical Energy (Rotational Force) Mechanical Energy
Motor

Electrical Drive
Systems employed for motion control are called as Drives.
It may employ any of prime movers such as diesel or petrol
engines, gas or steam turbines, steam engines, hydraulic
motors and electric motors, for supplying mechanical
energy for motion control.
Drives employing electric motors are called as Electrical
Drives.

Block diagram for Electrical Drives

Components of Block Diagram
• Power source
• Power Processor/power
modulator
• Motor
• Sensing unit
• Control unit
• Load

• Single phase AC
• Three Phase AC
• DC supply

Electrical Source
Voltage Rating::110V, 230V, 415V, 25KV
Current Rating:: 0.5A, 1A, 2A, 3A, 5A, 10A, 15A, 20A, 30A
Frequency-50Hz
Voltage Rating::5V, 6V, 12V, 24V, 48V, 220V
Current Rating:: 0.2A, 0.3A, 0.5A, 1.5A, 1A, 2A, 2.5A, 2A,
3A
There is no Frequency
• Current
• Voltage

• Modulates flow of power from the source to the
motor in such a manner that motor is imparted
speed torque characteristics required by the load
• During transient operations , such as starting,
braking and speed reversal . It restricts the source
and motor current within permissible value
• Converts electrical energy of the source in the
form suitable to motor.
• Selects the mode of operation

classification of power modulator:
(a) Converters:
Need for converter arises when nature of the available
electrical power is different than what is required for the
motor.
1.ac to dc converter
2.dc to dc converter
3.Inverters
4.cycloconverters

 Variable resistors are commonly used for the control of dc
and ac drives.
 Can be controlled manually or automatic.
 Stepless variation of resistance can be obtained using a
semiconductor switch in parallel with a fixed resistance;
 variation of duty ratio of the switch gives a stepless
variation in effective value of the resistance.
(b)Variableimpedances

(c)SwitchingCircuits:
 For changing motor connections to change it’s quadrant of
operation
 For operating motors and drives according to
predetermined sequence
 To disconnect motor when abnormal conditions
occur

Converters
Converter is used to convert the AC Voltage into DC Voltage
Converter
AC Voltage DC Voltage
T
V
T
V

Inverters
Inverter is used to convert the DC Voltage into AC Voltage
Inverter
DC Voltage AC Voltage
T
V
T
V

Chopper
Chopper is used to convert the fixed DC Voltage into Variable DC Voltage
Chopper
Fixed DC
Voltage
Variable DC
Voltage
T
V
T
V

Cyclo Converters
Cyclo Converter is used to convert the Fixed Frequency into Variable Frequency
Converter
Fixed
Frequency
Variable
Frequency

ELECTRICAL MOTORS
The possible form of drive motors are
(a). Dc motor fed from DC supply (chopper)
(b) Dc motor fed from AC supply (rectifier)
(c) Ac motor fed from AC supply (AC regulator)

AC Motor
Induction Motor
Compound Motor
Synchronous Motor
Series Motor
Shunt Motor
DC Motor Special Type Motor
Stepper Motor
BLDC Motor
Reluctance Motor
Types of Motor
Universal Motor

Most commonly used electrical drives are
DC MOTORS
1. Shunt motor
2. Series motor
3. Compound motor
4. Permanent magnet motor
AC MOTORS
INDUCTION MOTORS
1. Squirrel cage IM
2. Wound rotor IM
3. Linear IM
SYNCHRONOUS MOTORS
1. Wound field motor
2. Permanent magnet motor
Brushless dc motors
Stepper motors
Switched reluctance motors

Sensing Unit
 Sensor is used to sense the physical quantity and convert it to electrical
quantity
 It senses the certain drive parameter like motor current and speed.
 It mainly required either for protection or for closed loop operation.
Sensor
Physical
Quantity
Electrical
Quantity

Sensing Unit
In this unit, there are two functions are performed i. Speed Sensing ii. Current
Sensing
 SPEED SENSING
Speed sensing is required for implementation of closed loop speed control
schemes. Speed is usually sensed by Tachometers. When very high speed
accuracies required, as in computer peripherals and paper mills, etc.,
digital tachometers are used
 CURRENT SENSING
Current sensing employs two methods
1. Use of current sensor employing hall effect

Control Unit
• It controls the system motion without any damages according to
the sensing unit along with input command.
• The control unit controls the power modulator which operates
at small voltage and power levels. The control unit also
operates the power modulator as desired.
• Control unit consist of
 digital integrated circuit,
 Transistor and
 Microprocessor

Load
• Normally loads are designed for accomplishing the
given task.
• For example
 Fan,
 Pumps,
 Robots,
 Washing Machine

• The load has certain torque speed characteristic
• A motor having speed torque characteristic and capabilities
compatible to the load requirement is chosen

• Have flexible control characteristics
• Available in wide range of torque , speed and
power
• Not pollute the environment
• Adaptable in almost any operating conditions
• Can operate in all the four quadrant of
operations
• Smooth speed control

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1.general block diagram

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1.general block diagram