Power Electronics (3140915) MCQs

MCQs of DC-AC converters – Inverters

Showing 71 to 80 out of 100 Questions
5 6 7 8 9 10
71.
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
Answer:

Option (b)

72.
The modulation index (m) 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)
Answer:

Option (a)

73.
By controlling the modulation index (m), __________ can be controlled.
(a) gain
(b) output frequency
(c) harmonic content of the output voltage
(d) cosine component of the output voltage
Answer:

Option (c)

74.
In case of sinusoidal pulse width modulation with m(modulation index) < 1, if the number of pulses per half cycle (p) = 5, then
(a) harmonics of order 5 and 7 become significant
(b) harmonics of order 5 and 7 are eliminated
(c) harmonics of order 9 and 11 become significant
(d) harmonics of order 9 and 11 are eliminated
Answer:

Option (c)

75.
In case of sinusoidal pulse width modulation with m (modulation index) < 1, the order of the dominate harmonic can be raised by
(a) increasing the number of pulses
(b) reducing the number of pulses
(c) lowering the input voltage frequency
(d) raising the input voltage frequency
Answer:

Option (a)

76.
Increasing the number of pulses (p), ____________
(a) reduces the output voltage amplitude
(b) reduces the inverter efficiency
(c) improves the inverter efficiency
(d) none of the mentioned
Answer:

Option (b)

77.
In case of multiple pulse width modulation method, if the amplitudes of the reference wave and the carrier wave are made equal then, the pulse width =
(a) ∞
(b) 0
(c) 100 °
(d) none of the mentioned
Answer:

Option (b)

78.
In an inverter, if the fundamental output frequency is 45 Hz, then the frequency of the second lowest order harmonic will be
(a) 45 Hz
(b) 135 Hz
(c) 225 Hz
(d) 9 Hz
Answer:

Option (c)

79.
A single-phase bridge inverter has a square wave output voltage waveform, with odd harmonics present. What is the percentage of the fifth harmonic component to the fundamental component?
(a) 50 %
(b) 25 %
(c) 20 %
(d) 5 %
Answer:

Option (c)

80.
Control of frequency and control of voltage in 3-phase inverters is
(a) possible only through inverter control circuit
(b) possible through the control circuit of inverter and converter
(c) possible through inverter control of frequency and through converter control for voltage
(d) none of the mentioned
Answer:

Option (c)

Showing 71 to 80 out of 100 Questions
5 6 7 8 9 10