POWER ELECTRONICS AND DRIVES PART 24
1. In case of a single-pulse width modulation with the pulse width = 2d, to eliminate the 5th harmonic from the output voltage waveform, the value of the pulse width (2d) must be equal to
a) 72°
b) 86°
c) 91°
d) 5°
a) 72°
b) 86°
c) 91°
d) 5°
Answer: c
2. Several equidistant pulses per half cycle are used in ___________ type of modulation technique.
a) single-pulse
b) multiple-pulse
c) sine-pulse
d) equidistant-pulse
2. Several equidistant pulses per half cycle are used in ___________ type of modulation technique.
a) single-pulse
b) multiple-pulse
c) sine-pulse
d) equidistant-pulse
Answer: b
3. In the multiple-pulse width modulation method, the Fourier coefficient an is
a) (Vs/π) [ cos(nπ/2) cos(nd) ].
b) 0
c) (4Vs/nπ) [sin(nπ/2) sin(nd)].
d) (2Vs/nπ) [sin(nπ/2) sin(nd)].
3. In the multiple-pulse width modulation method, the Fourier coefficient an is
a) (Vs/π) [ cos(nπ/2) cos(nd) ].
b) 0
c) (4Vs/nπ) [sin(nπ/2) sin(nd)].
d) (2Vs/nπ) [sin(nπ/2) sin(nd)].
Answer: b
4. In the multiple-pulse width modulation method with two pulses per half cycle of width = d each and ɣ as the distance between the first pulse and ωt=0, has the Fourier coefficient bn =
a) (8Vs/π) [ cos(ɣπ/2) cos(nd/2) ].
b) 0
c) (4Vs/nπ) [sin(nɣ) sin(nd/2)].
d) (8Vs/nπ) [sin(nɣ) sin(nd/2)].
4. In the multiple-pulse width modulation method with two pulses per half cycle of width = d each and ɣ as the distance between the first pulse and ωt=0, has the Fourier coefficient bn =
a) (8Vs/π) [ cos(ɣπ/2) cos(nd/2) ].
b) 0
c) (4Vs/nπ) [sin(nɣ) sin(nd/2)].
d) (8Vs/nπ) [sin(nɣ) sin(nd/2)].
Answer: d
5. The amplitude of the nth harmonic of the two-pulse MPM waveform is given by __________
Let d be the width of a single pulse and ɣ be the distance from 0 to the centre of the first pulse.
a) (8Vs/nπ) sin(nɣ) sin(nd/2)
b) (4Vs/nπ) sin(nɣ) sin(nd/2)
c) (8Vs/nπ) sin(nπ) sin(nd/2)
d) (8Vs/nπ) sin(nɣ/2) sin(nd/2)
Answer:a
5. The amplitude of the nth harmonic of the two-pulse MPM waveform is given by __________
Let d be the width of a single pulse and ɣ be the distance from 0 to the centre of the first pulse.
a) (8Vs/nπ) sin(nɣ) sin(nd/2)
b) (4Vs/nπ) sin(nɣ) sin(nd/2)
c) (8Vs/nπ) sin(nπ) sin(nd/2)
d) (8Vs/nπ) sin(nɣ/2) sin(nd/2)
Answer:a
6. In case of MPM with two pulses per half cycle of width = d each and ɣ as the distance between the first pulse and ωt=0, for eliminating the nth harmonic from the output voltage, which of the following condition must be satisfied?
a) d = 2π
b) d = π
c) d = n°
d) d = 2π/n
a) d = 2π
b) d = π
c) d = n°
d) d = 2π/n
Answer: d
7. In case of MPM with two pulses per half cycle of width = d each and ɣ as the distance between the first pulse and ωt=0, for eliminating the nth harmonic from the output voltage, the value of gamma (ɣ) must be equal to
a) 0
b) π
c) π/n
d) d/n
7. In case of MPM with two pulses per half cycle of width = d each and ɣ as the distance between the first pulse and ωt=0, for eliminating the nth harmonic from the output voltage, the value of gamma (ɣ) must be equal to
a) 0
b) π
c) π/n
d) d/n
Answer: c
8. Find the peak value of the fundamental component of voltage with MPM with two pulses having pulse width = 36° and ɣ = 54°. The Fourier representation of the waveform is as follows.
a) 0.7484 x Vs
b) 1.414 x Vs
c) 0.637 x Vs
d) 2.54 x Vs
8. Find the peak value of the fundamental component of voltage with MPM with two pulses having pulse width = 36° and ɣ = 54°. The Fourier representation of the waveform is as follows.
a) 0.7484 x Vs
b) 1.414 x Vs
c) 0.637 x Vs
d) 2.54 x Vs
Answer: c
9. In the MPM method, the comparator is given _______ and _______ types of waveform at its input.
a) square, sine
b) square, quasi-square
c) sine, triangular
d) square, triangular
9. In the MPM method, the comparator is given _______ and _______ types of waveform at its input.
a) square, sine
b) square, quasi-square
c) sine, triangular
d) square, triangular
Answer: d
10. In MPM, the square wave is the ________ signal whereas the triangular wave is the ________ signal.
a) reference, carrier
b) base, reference
c) carrier, reference
d) none of the mentioned
10. In MPM, the square wave is the ________ signal whereas the triangular wave is the ________ signal.
a) reference, carrier
b) base, reference
c) carrier, reference
d) none of the mentioned
Answer: a
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