Power Electronics - Online Test

Q1.
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
Answer : Option C
Explaination / Solution:
No Explaination.


Q2.
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 average source current in Amps in steady-state is
Answer : Option B
Explaination / Solution:
No Explaination.


Q3. The Voltage Source Inverter (VSI) shown in the figure below is switched to provide a 50 Hz, square-wave ac output voltage (v0) across an R-L load. Reference polarity of v0 and reference direction of the output current i0 are indicated in the figure. It is given that R = 3 Ω, L = 9.55 mH.

In the interval when v0 < 0 and i0 > 0 the pair of devices which conducts the load current is 
Answer : Option D
Explaination / Solution:
No Explaination.


Q4. The Voltage Source Inverter (VSI) shown in the figure below is switched to provide a 50 Hz, square-wave ac output voltage (v0) across an R-L load. Reference polarity of v0 and reference direction of the output current i0 are indicated in the figure. It is given that R = 3 Ω, L = 9.55 mH.
Appropriate transition i.e., Zero Voltage Switching (ZVS) / Zero Current Switching (ZCS) of the IGBTs during turn-on / turn-off is
Answer : Option D
Explaination / Solution:
No Explaination.


Q5. Assuming the diodes to be ideal in the figure, for the output to be clipped, the input voltage vi must be outside the range

Answer : Option B
Explaination / Solution:



Q6. A single-phase SCR based ac regulator is feeding power to a load consisting of 5Ω resistance and 16 mH inductance. The input supply is 230 V, 50 Hz ac. The maximum firing angle at which the voltage across the device becomes zero all throughout and the rms value of current through SCR, under this operating condition, are
Answer : Option C
Explaination / Solution:




Q7. When a bipolar junction transistor is operating in the saturation mode, which one of the following statement is TRUE about the state of its collector-base (CB) and the baseemitter (BE) junctions?
Answer : Option C
Explaination / Solution:
No Explaination.


Q8. A single-phase thyristor-bridge rectifier is fed from a 230 V, 50 Hz, single-phase AC mains. If it is delivering a constant DC current of 10 A, at firing angle of 30º, then value of the power factor at AC mains is
Answer : Option C
Explaination / Solution:



Q9. A single-phase full-bridge voltage source inverter (VSI) is fed from a 300 V battery. A pulse of 120º duration is used to trigger the appropriate devices in each half-cycle. The rms value of the fundamental component of the output voltage, in volts, is
Answer : Option A
Explaination / Solution:



Q10. For the power semiconductor devices IGBT, MOSFET, Diode and Thyristor, which one of the following statements is TRUE?
Answer : Option D
Explaination / Solution:

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