# Power Electronics Questions and Answers – Type D Chopper

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

1. A type D chopper is a
d) none of the mentioned

Explanation: It is a two quadrant (I and IV) type B chopper as load current is always positive but the voltage can be positive or negative.

2. In a type-D chopper
a) current can flow in both the directions of the load
b) current cannot flow in both the directions of the load
c) voltage can only be positive
d) voltage can only be negative

Explanation: It is a two quadrant (I and IV) type B chopper. In quadrant I and IV current is only positive.

3. What is the load voltage value when both the chopper switches are on?

a) 0
b) Vs
c) 2Vs
d) Vs/2

Explanation: When both the switches are on, load is directly in parallel with Vs (source voltage).

4. For a type D chopper, the average value of output voltage will be positive when
a) Ton = Toff
b) Ton < Toff
c) Toff = 0
d) Ton > Toff

Explanation: When the chopper on time (SW1 and SW2) is more than the chopper off time than the average voltage will be positive. When the chopper switches are off, both the diodes are operating and the voltage is negative.

5. For a type D chopper, if duty cycle = 0.5 then the
a) average voltage is positive
b) average voltage is negative
c) average voltage is zero
d) chopper cannot be operated with duty cycle = 0.5

Explanation: When α = 0.5. Ton = Toff hence the positive and negative value of voltages become equal. Making the average voltage = 0 V.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. In the below given circuit, if only SW1 is operated then

a) the power flows from load to source
b) the power flows from source to load
c) the average voltage is positive
d) none of the mentioned

Explanation: If only one switch is operated, circuit is not completed and the current does not flow.

7. For a type D chopper, if duty cycle α < 0.5 then the
a) average voltage is positive
b) average voltage is negative
c) average voltage is zero
d) none of the mentioned

Explanation: α = Ton/T
If α < 0.5, Ton < Toff
The average value of voltage will be negative, as the switches will be off most of the times.

8. In the below given circuit, if Vo = -Vs then

a) both the chopper switches are on
b) only SW2 and D1 is active
c) both the chopper switches are off and both the diodes D1 and D2 are active
d) both the chopper switches are on and both the diodes D1 and D2 are reversed biased

Explanation: When diodes are operating, power flows from load to source and the inductor (L) in the load reverses its polarity.

9. Find the expression for average output voltage in a type D chopper on RL load.
a) Vs x Duty cycle (α)
b) Vs x T
c) Vs x (T – T)/T
d) Vs2/2

Explanation:
During Ton = Vs x Ton/T
During Toff = – Vs x Toff/T
Vo = Vs (Ton – Toff)/T.

10. Find the average output voltage for a type D chopper if it is given a dc supply of 220 V. Chopper frequency is 2 kHz and both the chopper switches are operated for 0.3 ms.
a) 220 V
b) 108 V
c) 98 V
d) 44 V

Explanation: T = 1/f = 0.5 ms
Ton = 0.3 ms
Toff = 0.2 ms
Vo = Vs (Ton – Toff)/T = 220 x (1/5) = 44 V.

Sanfoundry Global Education & Learning Series – Power Electronics.

To practice all areas of Power Electronics, here is complete set of 1000+ Multiple Choice Questions and Answers.