# Power Electronics Questions and Answers – PWM Inverters-3

«
»

This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “PWM Inverters-3”.

1. In the multiple pulse width modulation method, the firing pulses are generate during the interval when the
a) triangular wave exceeds the square modulating wave
b) square modulating wave exceeds the triangular wave
c) square wave amplitude is same as the triangular wave’s amplitude
d) none of the mentioned

Explanation: The firing pulses to turn on the SCRs (or any other equivalent device) are generated when the triangular carrier signal exceeds the square reference signal.

2. In MPM, ____________ order harmonics can be eliminated by a proper choice of __________ and _________
a) higher, d, ɣ
b) lower, d, ɣ
c) higher and lower, d, ɣ
d) none of the mentioned

Explanation: In multiple pulse width modulation, the lower order harmonics can be eliminated by proper choice of 2d and ɣ.

3. In ___________ type of modulation method, the pulse width is not equal for all the pulses.
a) multiple pulse width modulation
b) single pulse width modulation
c) sinusoidal pulse width modulation
d) none of the mentioned

Explanation: In SPWM, the pulse width is a sinusoidal function of the angular position of the pulse in a cycle.

4. In sinusoidal pulse width modulation, __________ wave is compared with a ___________ type of wave.
a) square, sinusoidal
b) sinusoidal, triangular
c) sinusoidal, quasi-square
d) none of the mentioned

Explanation: In SPWM, a high-frequency triangular wave is compared with a sinusoidal reference wave of the desired frequency.

5. In the sinusoidal pulse width modulation, __________ is the carrier wave signal.
a) square wave
b) triangular wave
c) sinusoidal wave
d) quasi-square wave

Explanation: In SPWM, a high-frequency triangular wave is compared with a sinusoidal reference wave of the desired frequency.

6. In the sinusoidal pulse width modulation, ____________ is the reference wave signal.
a) square wave
b) triangular wave
c) sinusoidal wave
d) quasi-square wave

Explanation: In SPWM, a high-frequency triangular wave is compared with a sinusoidal reference wave of the desired frequency.

7. In sinusoidal pulse width modulation, the comparator output is high when the
a) triangular wave has magnitude higher than the sinusoidal wave
b) sinusoidal wave has magnitude higher than the triangular wave
c) triangular wave has magnitude equal to the sinusoidal wave
d) none of the mentioned

Explanation: The comparator output is high when the sinusoidal wave (reference signal) has magnitude higher than the triangular wave (carrier signal).

8. In PWM, the comparator output is further given to a ____________
a) integrator
b) scr devices
c) trigger pulse generator
d) snubber circuit

Explanation: The comparator output is processed in a trigger pulse generator in such a manner that the output voltage wave of the inverter has a pulse width in agreement with the comparator output pulse width.

9. The modulation index (MI) is given by
Vr = peak value of the reference wave.
Vc = peak value of the carrier wave.
a) Vr/Vc
b) Vc/Vr
c) (1 + Vc/Vr)
d) 1/(Vc Vr)

Explanation: MI = Vr/Vc.

10. By controlling the modulation index (MI), __________ can be controlled.
a) gain
b) output frequency
c) harmonic content of the output voltage
d) cosine component of the output voltage

Explanation: MI controls the output voltage waveform.

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. 