# Power Electronics Questions and Answers – Type E Choppers-1

This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “Type E Chopper-I”.

1. Identify the given circuit

a) type D chopper
b) two quadrant type C chopper
c) type E chopper
d) type F chopper

Explanation: It is a type E chopper. Type C consists of 4 diodes and 4 IGBT switches.

2. A type C chopper consists of __________ diodes and _________ switches in anti-parallel.
a) 2, 2
b) 3, 3
c) 4, 4
d) 3, 4

Explanation: Type C consists of 4 diodes and 4 switches arranged in anti-parallel. The switches and diodes are always numbered occurring to the quadrant in which they operate.

3. A type C chopper can operate in
c) Ist, IInd and IIIrd quadrants

Explanation: Type C can operate in all the four quadrants by controlling appropriate switches and reversing the emf in the load circuit.

4. For the first quadrant operation of type E chopper

a) Only CH1 is on
b) CH1 and CH2 is on
c) CH1 and CH3 is on
d) CH1 and CH4 is on

Explanation: With CH1 and CH4 on, load voltage = Vs and load current flows. Both V and I are positive giving Ist quadrant operation.

5. For the second quadrant operation of type E chopper

a) Only CH2 is on
b) CH1 and CH2 is on
c) CH2 and CH3 is on
d) CH2 and CH4 is on

Explanation: With CH2 on, negative current flows through L, CH2, CH3 and CH4. When CH2 is turned off, current is fed back to the diodes by D1 and D4. Load voltage is positive and current is negative, hence second current operation is operated.

6. For a type E chopper, when CH2 is first on and then switched off then the

a) power flows from source to load
b) power flows from load to source
d) none of the mentioned

Explanation: With CH2 on, negative current flows through L, CH2, CH3 and CH4. When CH2 is turned off, current is fed back to the diodes by D1 and D4. Load voltage is positive and current is negative, hence second current operation is operated.

7. What is the expression for load voltage when the chopper is operated in the second quadrant?
a) Vs
b) E
c) 0
d) E + Ldi/dt

Explanation: In the second quadrant, the chopper acts as a step up chopper and current flows from the load to source. With CH2 on, negative current flows through L, CH2, CH3 and CH4.

8. For a type E chopper operating in the first quadrant, find the expression for average output voltage.
a) Vs
b) E – Ldi/dt
c) 0
d) E + Ldi/dt

Explanation: With CH1 and CH4 on, load voltage = Vs and load current flows.

9. The load emf E must be reversed for
a) first and second quadrant operation
d) both third and fourth quadrant operation

Explanation: The load E must be reversed for both third and fourth quadrant operation for proper current flow.

10. For the third quadrant operation of type E chopper

a) CH1 is on
b) CH2 and CH1 are on
c) CH3 is on
d) None of the mentioned

Explanation: For third quadrant operation of type E chopper, CH2 is kept on and CH3 is operated. First both CH2 and CH3 are on, and then CH3 is switched off thus the current freewheels through CH2 and D4.

Sanfoundry Global Education & Learning Series – Power Electronics.

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