# Power Electronics (Test 2)

## Gate Exam : Ee Electrical Engineering

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Power Electronics
| Power Electronics |
Q.1
For the power semiconductor devices IGBT, MOSFET, Diode and Thyristor, which one of the following statements is TRUE?
A. All of the four are majority carrier devices.
B. All the four are minority carrier devices
C. IGBT and MOSFET are majority carrier devices, whereas Diode and Thyristor are minority carrier devices.
D. MOSFET is majority carrier device, whereas IGBT, Diode, Thyristor are minority carrier devices.
Explaination / Solution:

MOSFET → Majority carrier device (NMOS, PMOS) Diode → both majority & minority carrier device Transister → Npn, pnp IGBT → input is MOSFET, Output is BJT

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Q.2
For the circuit shown in the figure below, assume that diodes D1D2 and D3 are ideal.

The DC components of voltages v1 and v2, respectively are
A. 0 V and 1 V
B. -0.5 V and 0.5 V
C. 1 V and 0.5 V
D. 1 V and 1 V
Explaination / Solution:

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Q.3
In the 3-phase inverter circuit shown, the load is balanced and the gating scheme is 1800 -conduction mode. All the switching devices are ideal

The rms value of load phase voltage is
A. 106.1 V
B. 141.4 V
C. 212.2 V
D. 282.8 V
Explaination / Solution:

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Q.4
In the 3-phase inverter circuit shown, the load is balanced and the gating scheme is 1800 -conduction mode. All the switching devices are ideal
If the dc bus voltage V= 300 V, the power consumed by 3-phase load is
A. 1.5 kW
B. 2.0 kW
C. 2.5 kW
D. 3.0 kW
Explaination / Solution:

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Q.5
The input voltage VDC of the buck-boost converter shown below varies from 32 V to 72 V. Assume that all components are ideal, inductor current is continuous, and output voltage is ripple free. The range of duty ratio D of the converter for which the magnitude of the steady state output voltage remains constant at 48 V is

A.
B.
C.
D.
Explaination / Solution:

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Q.6
Assuming that the diodes in the given circuit are ideal, the voltage V0 is

A. 4V
B. 5V
C. 7.5V
D. 12.12V
Explaination / Solution:
No Explaination.

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Q.7
The power electronic converter shown in the figure has a single-pole double-throw switch. The pole P of the switch is connected alternately to throws A and B. The converter shown is a _______

A. step-down chopper (buck converter)
B. half-wave rectifier
C. step-up chopper (boost converter)
D. full-wave rectifier
Explaination / Solution:
No Explaination.

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Q.8
Figure shows a composite switch consisting of a power transistor (BJT) in series with a diode. Assuming that the transistor switch and the diode are ideal , the I-V characteristic of the composite switch is

A.
B.
C.
D.
Explaination / Solution:
No Explaination.

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Q.9
The fully controlled thyristor converter in the figure is fed from a single-phase source. When the firing angle is 0°, the dc output voltage of the converter is 300V. What will be the output voltage for a firing angle of 60°, assuming continuous conduction?

A. 150 V
B. 210 V
C. 300 V
D. 100π V
Explaination / Solution:
No Explaination.

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Q.10
In the figure shown below, the chopper feeds a resistive load from a battery source. MOSFET Q is switched at 250 kHz, with a duty ratio of 0.4. All elements of the circuit are assumed to be ideal

The Peak to Peak source current ripple in amps is
A. 0.96
B. 0.144
C. 0.192
D. 0.288