Power Electronics (3140915) MCQs

MCQs of DC-DC converters - Switching Voltage Regulators

Showing 21 to 30 out of 51 Questions
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21.
A step down chopper has input dc voltage of 220 V and R = 10 Ω in series with L = 65 mH. If the load current varies linearly between 11 A and 17 A, then find the duty cycle δ.
(a) 1
(b) 0.4
(c) 0.6
(d) 0.7
Answer:

Option (d)

22.
For a step-up/step-down chopper, if α (duty cycle) = 0.5 then
(a) Vo = Vs
(b) Vo < Vs
(c) Vo > Vs
(d) none of the mentioned
Answer:

Option (a)

23.
A step-down chopper is also called as a
(a) first-quadrant chopper
(b) second-quadrant chopper
(c) third-quadrant chopper
(d) fourth-quadrant chopper
Answer:

Option (a)

24.
In case of TRC (Time Ratio Control), _________ is varied
(a) duty cycle
(b) firing angle
(c) supply frequency
(d) supply voltage magnitude
Answer:

Option (a)

25.
In case of TRC, α (Duty cycle) is varied to change the average value of output voltage.
(a) Vs
(b) Ton
(c) T
(d) f
Answer:

Option (b)

26.
In case of variable frequency system __________ is varied
(a) T
(b) Ton
(c) Toff
(d) supply frequency
Answer:

Option (a)

27.
In pulse width modulation scheme, _________ is kept constant.
(a) Vs
(b) Ton
(c) T
(d) Toff
Answer:

Option (b)

28.
In case of a constant frequency system, Ton = (1/4)T. If the chopping frequency 2 kHz, find the value of Toff.
(a) (1/8) ms
(b) (3/8) ms
(c) (1/8) μs
(d) (3/8) μs
Answer:

Option (b)

29.
In case of frequency modulation system, ________ is kept constant.
(a) T
(b) Ton
(c) Toff
(d) Either Ton or Toff
Answer:

Option (d)

30.
The control strategy in which on and off time is guided by the pervious set of values of a certain parameter is called as
(a) time ratio control
(b) pulse width modulation
(c) current limit control
(d) constant frequency scheme
Answer:

Option (c)

Showing 21 to 30 out of 51 Questions
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