# Power Electronics Questions and Answers – Voltage Control in Inverters

«
»

This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “Voltage Control in Inverters”.

1. The external control of ac output voltage can be achieved in an inverter by
a) connecting a cyclo-converter
b) connecting an ac voltage controller between the output of the inverter and the load
c) connecting an ac voltage controller between the dc source and inverter
d) connecting an ac voltage controller between the load and the dc source

Explanation: By connecting a AC voltage controller, the ac output from the inverter can be varied and then fed to the load.

2. The series-inverter control method is a/an
a) internal voltage control method
b) external frequency control method
c) external voltage control method
d) none of the mentioned

Explanation: It is a external voltage control method where the outputs of the two inverters are connected to the transformers where the secondary of the transformer sums up the two input voltages.

3. In the series-inverter control method
a) two inverters are connected back-to-back
b) the output from the inverter is taken serially
c) output voltages of two inverters are summed up with the help of a transformer
d) output voltages of two inverters are summed up with the help of a third inverter

Explanation: It is a external voltage control method where the outputs of the two inverters are connected to the transformers where the secondary of the transformer sums up the two input voltages.
Note: Join free Sanfoundry classes at Telegram or Youtube

4. In case of the series inverter control, if two inverters are connected in series through a transformer, and two secondary voltages are V1 and V2, then the resultant output is given by
a) V1 + V2
b) √(V12 + V22)
c) [V12 + V22 + 2.V1.V2.cosθ]1/2
d) [V12 + V22 + 2.V1.V2.sinθ]1/2

Explanation: The resultant output will be the phasor sum of V1 and V2.

5. External control of dc input voltage can be obtained by the use of a
a) transformer
b) chopper
c) inverter
d) converter

Explanation: A chopper is used to control the dc input voltage to the inverter, which then converters the variable dc to variable ac.

6. In the external control of dc input voltage
a) a chopper is placed just after the inverter block
b) a chopper is placed just after the filter block
c) a chopper is placed before the filter and the inverter block
d) none of the mentioned

Explanation: Constant AC – Rectifier – Chopper – Filter – Inverter.

7. __________ method is an internal method for controlling the inverter output voltage.
a) series connection of inverters
b) chopper method
c) commutating capacitor
d) pulse width modulation

Explanation: The PWM method, (pulse width modulation method) is an internal controlling method.

8. In the PWM method
a) external commutating capacitors are required
b) more average output voltage can be obtained
c) lower order harmonics are minimized
d) higher order harmonics are minimized

Explanation: In all the PWM methods, only odd harmonics are present. The lower order harmonics are eliminated along with its output voltage control.

9. Which of the following is not a PWM technique?
a) Single-pulse width modulation
b) Multiple-pulse width modulation
c) Triangular-pulse width modulation
d) Sinusoidal-pulse width modulation

Explanation: There is no such “Triangular” PWM.

10. In pulse width modulation
a) the output voltage is modulated
b) the input voltage is modulated
c) the gating pulses are modulated
d) none of the mentioned

Explanation: In PWM, the gating pluses are modulated, i.e. the gating pulses or firing pulses are made to go on of rapidly which changes the output voltage values accordingly.

Sanfoundry Global Education & Learning Series – Power Electronics.

To practice all areas of Power Electronics, here is complete set of 1000+ Multiple Choice Questions and Answers. 