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GATE 2019: Champion Test Power Electronics (App update required to attempt this test)

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Question 1

In the LC circuit shown below, inductance L = 2mH and capacitance C = 20 µF. The initial current through voltage is 100V. If the switch is closed at t=0, then the current flowing through the circuit is

Question 2

In the following chopper, the duty ratio of switch S is 0.4. If the inductor and capacitor are sufficiently large to ensure continuous inductor current and ripple free capacitor voltage, the charging current (in Ampere) of the 5 V battery, under steady – state, is _______.

Question 3

The power MOSFET usually has an internal diode known as body diode connected between the source and the drain. What is the purpose of this body diode?

Question 4

In the circuit shown below:

The average output current I0 = 0.5 A and switching frequency is 25 kHz.
The peak to peak ripple current of Inductor ΔI is _____ A. 

Question 5

The given rectifier circuit has a source voltage of 150 sin ωt, and a load resistor of 40 Ω. Determine the average load current, if the thyristors are fired at ωt = 30°

        

Question 6

A single phase VSI is switched using SPWM technique. It is supplied by a dc source of 150V and pulse width of 1200. Find the rms value of fundamental component present in the output voltage waveform.

Question 7

The SCR in the circuit shown has a latching current of 40 mA. A gate pulse of 50 μs is applied to the SCR. The maximum value of R in Kohms to ensure successful firing of the SCR is _________.(Take the values for three decimal places only) 

Question 8

A fully controlled converter bridge feeds a highly inductive load with ripple free load current. The input supply (Vs) to the bridge is a sinusoidal source. Triggering angle of the bridge converter is α= 30o The input power factor of the bridge is_________.
[write the answer upto three decimal point]

Question 9

A diode circuit feeds an ideal inductor as shown in the figure.Given Vs = 100sin(ωt) V, where ω=100π rad/sec and L = 31.83 mH. The initial value of inductor current is zero. Switch S is closed at t = 2.5 ms. The peak value of inductor current iL (in A) in the first cycle is ________.

Question 10

A 3-phase 50 Hz square wave (6-step) VSI feeds a 3-phase, 4 pole induction motor. The VSI line voltage has a dominant 5th harmonic component. If the operating slip of the motor with respect to fundamental component voltage is 0.04, the slip of the motor with respect to 5th harmonic component of voltage is _____.
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Nov 19ESE & GATE EE