This document discusses the operation of a 4-quadrant chopper. It describes the circuit configurations and operating principles for each quadrant. In the first quadrant, CH1 and CH4 are on and it acts as a step-down chopper. In the second quadrant, CH2 is on and it acts as a step-up chopper. In the third quadrant, CH3 is on and the load polarity is reversed. In the fourth quadrant, CH4 is on and it acts as a step-up chopper with the voltage positive and current negative.

1. 4 QUADRANT OPERATION WITH ONE SOLVED
PROBLEM
By
Chandra preethi B(14F09)
Jeyamurugan J(14F64)
Vinith kumar M(14F60)

2. BASIC OPERATION OF A CHOPPER
CHOPPER :-
CONSTANT DC
VOLTAGE
VARIABLE DC
VOLTAGE

3. FIRST QUADRANT CIRCUIT

4. FIRST QUADRANT
• Chopper CH4 will be continuously on; CH3,CH2 will be off. CH1 will be
operated
• CH1 &CH4 is on load voltage(V0) will be equal to source
voltage(Vs).Load current (I0) will begin to flow.
• V0 and I0 will be positive
• CH1 is turned off, positive current free wheels through CH4 & diode
D2
• V0 is less than Vs
• Act as a stepdown chopper or buck convertor. Suitable for motoring
operation

5. SECOND QUADRANT CIRCUIT

6. SECOND QUADRANT
• Chopper CH2 will be ON and other three are kept OFF.
• CH2 is ON negative current flows through inductor L,CH2,E and
D4.Energy is stored in the inductor.
• CH2 is OFF current will be fed back to source through D1 & D4.Energy
is discharged in the inductor.
• Voltage is positive, current is negative
• Power is fed back from load to source
• V0 is greater than Vs
• Act as step-up chopper or boost convertor. suitable for forward
braking operation.

7. 3RD QUADRANT CHOPPER CIRCUIT

8. THIRD QUADRANT
• CH1 will be kept OFF, CH2 will be ON and CH3 is operated
• Here the polarity of the load should be reversed
• As CH3 is ON ,the load get connected to source VS
• V0 and I0 Will be negative
• Act as a step-down chopper

9. 4th QUADRANT CHOPPER CIRCUIT

10. FOURTH QUADRANT
• CH4 will be operated and CH1,CH2 and CH3 will be OFF
• CH4 is ON positive current starts to flow through CH4,D2,E and
inductor will store energy.
• CH4 is turned OFF the current is feedback to the source through
diodes D2 & D3
• V0 is negative but I0 is positive
• The power is fed back from load to source
• Act as a step-up chopper

11. QUIZ
• When ch4 is on , ch3 and ch2 is off and ch1 is operated in which
quadrant?
A)I quadrant b)II quadrant C)III quadrant D)IV quadrant
• In which quadrants the voltage across the load will be reversed?
A)I&II B)II&III C)III&IV D)I&IV
• What will be the value of duty cycle if Ton =T?
A)0 B)1 C)0.5 D)cannot be determined
• What is the a value for a step down chopper?
A)<0 B)>1 C)0<a<0.5 D)0.5<a<1

12. Thank you