Chopper-fed DC drives use a chopper circuit connected between a fixed DC voltage source and a DC motor to vary the motor's armature voltage. A chopper is a high-speed on/off semiconductor switch that connects and disconnects the source to the load. Chopper circuits are used to control both separately excited and series DC motor circuits. Chopper-fed drives allow operation in four quadrants by controlling the chopper switches, enabling forward or reverse motoring and regeneration.

1. CHOPPER-FED DC DRIVES
Presented by
Jenitha.J

2. CHOPPER
• Chopper is a static device.
• It is a device which converts fixed dc input into variable
dc output voltage.
• It is also known as dc-to-dc converter.
• Widely used for motor control.
• And it is also used in switched mode power supply.
• Converter offers greater efficiency, faster response,
lower maintenance, smaller size and smooth control.

3. CHOPPER FED DC DRIVES
• A dc chopper is connected between a fixed-voltage dc
source and dc motor to vary the armature voltage.
• A chopper is a high speed on/off semiconductor switch
which connects source to load and disconnects the load
from source at a fast speed.
• Choppers are used to get variable dc voltage from a dc
source of fixed voltage.
• Chopper circuits are used to control both separately
excited and Series circuits.

4. ADVANTAGES OF CHOPPER CIRCUITS
• Ripple content in the output is small.
• Current drawn by the chopper is smaller than the
converters.
• Peak/average and rms/average current ratios are small.
• The chopper is supplied from a constant dc voltage using
batteries.
• Chopper circuit is simple and can be modified to provide
regeneration and the control is also simple.

5. MULTIQUADRANT CHOPPER DRIVES
o Forward motoring (I-Quadrant)
o Forward Regeneration (II-Quadrant)
o Reverse motoring ( III-Quadrant)
o Reverse Regeneration (IV-Quadrant)

6. FORWARD MOTORING:
Q1
T1 & T4 is ON
Current Flow : VS
+ _ T1 _Motor_T4_VS
-
Current Ia & Va are positive
Operates in First Quadrant

7. Q2
T2 is OFF. Diode D2 is FB
Current flows through D3 & D2
 Current Ia is negative & Va is positive.
Operates in second quadrant.
FORWARD REGENERATION

8. Q3
T3 & T2 is ON
Current Flow : Vdc
+ _ T3 _Motor_T2_Vdc
-
Current Ia & Va are negative
Operates in third Quadrant
REVERSE MOTORING:

9. Q4
T4 is Turned Off, D4 is FB
Current Flows through Va+ - D1 – D4 – Va-
Va is negative. But current Ia is positive
Operates in fourth quadrant
REVERSE REGENERATION

10. 10
Single-Phase Half-Wave Converter Drive
(1 cos )
2
0
(1 cos )
0
m
a a
a
m
f f
f
V
V
V
V


 


 
 
 
 
 

11. 11
Quadrant of Operation

12. 12
Waveform

13. 13
Single-Phase Semi-converter Drives
(1 cos )
0
(1 cos )
0
m
a a
a
m
f f
f
V
V
V
V


 


 
 
 
 
 

14. 14
Quadrant of Operation
Semiconverter – one quadrant converter
One polarity of output voltage and current

15. 15
Waveform Summary

16. 16
Single-Phase Full-Converter Drives

17. 17
Quadrant of Operation
Full converter – two quadrant converter
Output voltage polarity can be positive or negative
Output current has one polarity

18. 18
Waveform Summary

19. THANK YOU