This document discusses various methods of speed control for DC motors, including flux control and armature voltage control. It also describes different laboratory methods like the Ward Leonard method using induction, synchronous, or diesel prime movers. Types of speed control discussed include open loop and closed loop control. Static voltage control methods for AC and DC supply like converters, choppers, and PWM methods are also summarized. Preferences for different types of DC motors are stated at the end.

1. SUBMITTED BY--VIPIN KUMAR SINGH
SHAHBAAZ AHMED
RAVI YADAV
SHRAVAN KUMAR
UNDER THE GUIDANCE OF—
Mr. RANJIT KUMAR

2. METHODS OF SPEED CONTROL
 1. FLUX CONTROL—
Speed of dc motor is inversely
 prop. to field flux
 So speed can be controlled above base speed
 It is constant power speed control.
 Speed below base speed is not possible in this
method.

3. METHODS OF SPEED CONTROL
 2. ARMATURE VOLTAGE CONTROL Speed of dc machine is directly prop. to
armature voltage.
 So speed below base speed can be controlled.
 It is a constant torque method.
 Speed reversal is possible.

4. LABORATORY METHOD
1. WARD LEONARD METHOD
A) USING INDUCTION PRIME MOVER
 Induction prime mover is required with
flywheel when there is heavy and
intermittent load .
 Flywheel works as a reservoir of energy and
make a flow of energy when requires.

5. LABORATORY METHOD
B) USING SYNCHRONOUS PRIME MOVER
• When P.F. improvement is requored
synchronous motor is used with
overexcitation.
• Overexcitation of field also enhance
maximum torque capability.
• Application-rolling mills, elevator etc

6. LABORATORY METHOD
C) USING DIESEL PRIME MOVER
• Generater is driven by constant speed diesel
engine.
• Hence we have to concentrate over motor
speed only
• Regenerative braking is not possible.

7. TYPES OF SPEED CONTROL
1. OPEN LOOP SPEED CONTROL This type of control is applied when low
ratings are involved.
 In this method simple rheostat is used as
power loss in it is less at low power.
 Maximum speed obtained is 20*base speed.
 For higher rating, it is not applicable.

8. TYPES OF SPEED CONTROL
• 2. CLOSED LOOP SPEED CONTROL
• This meets the following requirements• 1)protection
• 2)enhancement of speed of response
• 3)to improve steady state accuracy.
• Inner current control is required.
• PI,PD,PID may be used as per requirement.

9. STATIC VOLTAGE CONTROL FOR AC
SUPPLY
 1. CONVERTOR
 A). UNCONTROLLED CONVERTOR USING
TAPPED TRANSFORMER
 B). HALF CONTROLLED CONVERTOR
 C). FULL CONVERTOR

10. STATIC VOLTAGE CONTROL FOR AC
SUPPLY
 2. DUAL CONVERTOR
 Dual converter allows current as well as
voltage in either direction.
 Hence 4 quadrant operation.
 Hence motoring and regenerative braking can
be done by adjusting firing angle.

11. DUAL CONVERTER-


12. STATIC VOLTAGE FOR DC SUPPLY
 1. USING CHOPPER(DC TO VARIABLE DC)
 IGBT,IGCT,GTO,MOSFET are used in place of
scr .
 Important feature of chopper control is easier
regenerative braking.
 Type A –MOTORING
 TYPE B-REGENERATIVE BRAKING
 TYPE C -BOTH

13. CHOPPER


14. PWM METHOD OF VOLTAGE
CONTROL
 This is a supporting method, but can be used





individually.
It reduces the harmonics of output.
In this a comparator compare the oscillator wave with
square dc wave, and gives the trigger to later circuit.
Later circuit may be involved of converter, chopper.
This circuit gives output according to the triggered
pulses.
At high power level this method becomes costly.

15. PWM METHOD OF VOLTAGE
CONTROL


16. PREFERENCES OF DC MOTORS
 1. BRUSHLESS DC MOTORS.
 2. SEPERATELY EXCITED DC MOTOR.
 3. SHUNT EXCITED DC MOTOR.
 4. SERIES EXCITED DC MOTOR.

17. REFERENCES P.S. BIMBHRA- ‘POWER ELECTRONICS’-KHANNA
PUBLICATION
 GOPAL K. DUBEY-NAROSA PUBLISHING HOUSEII EDITION-2011
 P.S. BIMBHRA-ELECTRICAL MACHINERY-KHANNA
PUBLICATION