Power Electronics Questions and Answers – Single Phase VSI-2

This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “Single Phase VSI-2”.

1. What is the voltage across the R load when only T2 is conducting?
Find the voltage across the R load when only T2 is conducting
a) Vs
b) Vs/2
c) 2Vs
d) Zero
View Answer

Answer: b
Explanation: Considering T2 as an ideal switch, the load is directly connected to the lower voltage source when T2 is on.

2. The voltage in a single phase half wave inverter varies between
a) Vs and 0
b) Vs/2 and 0
c) Vs/2 and –Vs/2
d) Vs and –Vs
View Answer

Answer: c
Explanation: It varies between –Vs/2 and Vs/2 as the upper and lower thyristors/IGBTs are fired in sequence.

3. Below given is a
The half wave inverter with MOSFET switches in given figure
a) SCR based inverter
b) MOSFET based inverter
c) IGBT based inverter
d) None of the mentioned
View Answer

Answer: b
Explanation: It is a half wave inverter with MOSFET switches. The diodes are used to bypass the negative current.
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4. The output of a single-phase half bridge inverter on R load is ideally
a) a sine wave
b) a square wave
c) a triangular wave
d) constant dc
View Answer

Answer: b
Explanation: Due to rapid switching on and off of the devices, it seems to be a square wave. But practically it is a B-wave.

5. In the below given circuit, T1 is fired at 0,T and so on and T2 at T/2, 3T/2 etc. What is the frequency of the alternating voltage obtained?
The half wave inverter with MOSFET switches in given figure
a) 50 Hz
b) T Hz
c) 1/T Hz
d) T/2 Hz
View Answer

Answer: c
Explanation: T1 conducts from 0 to T/2 and T2 from T/2 to T. Hence, 1 cycle is completed in T time. f = 1/T Hz.
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6. In the below circuit, if Vs/2 = 50 V. Find, the rms AC voltage that would be ideally obtained.
The half wave inverter with MOSFET switches in given figure
a) 50 V
b) 100 V
c) 0.707 x 50 V
d) 0.707 x 100 V
View Answer

Answer: c
Explanation: Peak value would be = 50 V
RMS = Peak/√2 = Peak x 0.707 V.

7. Find the conduction time of the diodes if the SCRs are fired at 0 and T/2 respectively in a single phase half wave inverter with R load.
a) 0
b) T/2
c) 2/T
d) insufficient data
View Answer

Answer: a
Explanation: With R load, the diodes do not come into play.
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8. The output current wave of a single-phase full bridge inverter on RL load is
a) a sine wave
b) a square wave
c) a triangular wave
d) constant dc
View Answer

Answer: c
Explanation: On RL load, the SCRs are revised biased due to the voltage drops across the diodes and negative current flows.

9. Single-phase full bridge inverters requires
a) 4 SCRs and 2 diodes
b) 4 SCRs and 4 diodes
c) 2 SCRs and 4 diodes
d) 2 SCRs and 2 diodes
View Answer

Answer: b
Explanation: Full bridge inverters require 4 SCR and 4 diodes along with a two wire dc source.
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10. Identify the circuit given below.
The full wave bridge inverter using 4 diodes & 4 SCRs
a) Full wave series inverter
b) Half wave series inverter
c) Full wave bridge inverter
d) Full wave parallel inverter
View Answer

Answer: c
Explanation: It is a full wave bridge inverter using 4 diodes and 4 SCRs.

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.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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