Power Electronics (3140915) MCQs

MCQs of DC-DC converters - Switching Voltage Regulators

Showing 31 to 40 out of 51 Questions
31.
In the current limit control method, the chopper is switched off when
(a) load current reaches the lower limit
(b) load current reaches the upper limit
(c) load current falls to zero
(d) none of the mentioned
Answer:

Option (b)

32.
Which of the following mentioned control strategy/strategies would require a feedback loop?
(a) pwm
(b) constant frequency system
(c) current limit control
(d) none of the mentioned
Answer:

Option (c)

33.
In the current limit control method, when the load current reaches a predefined lower value, then
(a) the chopper is switched off
(b) the chopper is switched on
(c) the source voltage is removed
(d) load voltage goes to zero
Answer:

Option (b)

34.
What is the expression for load voltage when the chopper is operated in the second quadrant?
(a) Vs
(b) E
(c) 0
(d) E + L[di/dt]
Answer:

Option (d)

35.
For a type E chopper operating in the first quadrant, find the expression for average output voltage.
(a) Vs
(b) E – Ldi/dt
(c) 0
(d) E + Ldi/dt
Answer:

Option (a)

36.
The load emf E must be reversed for
(a) first and second quadrant operation
(b) third quadrant operation
(c) fourth quadrant operation
(d) both third and fourth quadrant operation
Answer:

Option (d)

37.
For the type E chopper to be operated in the fourth quadrant
(a) only one switch is operated
(b) two switches are operated
(c) three switches are operated
(d) all the switches are operated
Answer:

Option (a)

38.
In a type E chopper, if all the four chopper switches are closed simultaneously then
(a) load is short circuited
(b) supply is short circuited
(c) both load and supply are shorted
(d) none of the mentioned.
Answer:

Option (b)

39.
A type A step down chopper has Vs = 220 V and is connected to RLE load. With R = 1 Ω, E = 24 V and L large enough to maintain continuous conduction. Find the average value of load current for a duty cycle of 30 %.
(a) 100 A
(b) 22 A
(c) 42 A
(d) 16.5 A
Answer:

Option (c)

40.
The process of commutating a SCR by applying a reverse voltage to an SCR through a previously charged capacitor is called as
(a) capacitor commutation
(b) forced commutation
(c) voltage commutation
(d) current commutation
Answer:

Option (c)

Showing 31 to 40 out of 51 Questions