1. A single-phase, voltage source, square wave inverter feeds a pure inductive load. The waveform of the current will be

- triangular
- trapezoidal
- rectangular
- sinusoidal

2. In the sinusoidal pulse-width modulation scheme, if the zero of the triangular wave coincides with the zero of the reference sinusoidal, then the number of pulse per half cycle is

$\\a. \frac{f_c}{2f}\\ \\ b. \frac{f_c}{2f}+1\\ \\ c. \frac{2f_c}{f}\\ \\ d. \frac{f_c}{2f}-1$

3. In a single-phase full bridge inverter what is the advantages of a unipolar switching over the bipolar switching?

- Apparent doubling of the switching frequency
- elimination of 5
^{th}and 7^{th}harmonics - increase of the fundamental component by a factor of 115 for the same DC input voltage
- none of the above

4. A voltage source inverter is used when source and load inductances are respectively

- small and small
- large and large
- large and small
- small and large

5. For a 1-phase full-bridge inverter fed from 48 V dc and connected to load resistance of 2.4 Ω, the RMS value of fundamental component of output voltage is

- 43.2 V
- 34.4 V
- 21.6 V
- 20 V

6. A voltage source inverter (VSI) is normally employed when

- both source inductance and load inductance are large
- both source inductance and load inductance are small
- source inductance is small and load inductance is large
- source inductance is large and load inductance is small

7. In a single-phase VSI bridge inverter, the load current is I_{o} = 200sin(ωt – 45°) mA. The d.c. supply voltage is 220 V. What is the power drawn from the supply?

- 34.03 W
- 27.25 W
- 19.8 W
- 9.8 W

8. A single-phase full bridge inverter is connected to a load of 2.4 Ω. The d.c. input voltage is 48 V. What is the r.m.s. output at fundamental frequency?

$\\a. \frac{4\times 48}{\sqrt{2}\pi } V\\ \\ b. \frac{2\times 48}{\sqrt{2}\pi } V\\ \\ c. \frac{4\times 48}{\pi } V\\ \\ d. \frac{2\times 48}{\pi } V$

9. A single-phase half-bridge inverter has input voltage of 48 V DC. Inverter is feeding a load of 2.4 Ω. The RMS output voltage at fundamental frequency is

$\\a. \frac{4\times 48}{\sqrt{2}\pi } V\\ \\ b. \frac{2\times 48}{\sqrt{2}\pi } V\\ \\ c. \frac{4\times 48}{\pi } V\\ \\ d. \frac{2\times 48}{\pi } V$

10. Which one of the following statements is correct?

A voltage source inverter is normally employed

- when both the source and load have low values of impedance and reactance respectively.
- when both the source and load have high values of impedance and reactance respectively.
- when the source has high impedance and load has low reactance
- when the source has low impedance and load has high reactance

11. A single-phase inverter has square wave output voltage. What is the percentage of the fifth harmonic component in relation to the fundamental component?

- 10%
- 20%
- 30%
- 40%

12. Compared to a single-phase half-bridge inverter, the output power of a single-phase full-bridge inverter is higher by a factor of

- 2
- 8
- 4
- 12

13. In case of voltage source inverter, free-wheeling can be needed for the load of

- back emf nature
- resistive nature
- capacitive nature
- inductive nature

14. The main application of multilevel inverter is in

- voltage regulator
- synchronous buck converter
- dc motor drive
- reactive power compensation

15. Current source inverters are suitable for supply power to

- RL loads
- Inductive loads
- Capacitive loads
- All loads

16. A current source inverter is obtained by inserting a large

- capacitance in series with dc supply
- inductance in parallel with dc supply
- capacitance in parallel with dc supply
- inductance in series with dc supply

17. A single-phase current source inverter is connected with capacitive load only the waveform of the output voltage across the capacitor for constant source current will be

- step function
- triangular wave
- square wave
- sine wave

18. In 3-phase inverter with 180° conduction mode the number of switches that is on at any instant of time is

- 4
- 3
- 2
- 1

19. What is the region of operation of a 3-phase inverter employing sinusoidal PWM when the peak-to-peak values of both the carrier and the modulating waves are made equal?

- six-step operation
- boundary of linear modulation and over modulation
- over modulation
- linear modulation

20. What should be the frequency modulation ratio (m_{f}) for a 3-phase inverter, if the m_{f}^{th} harmonic and its odd multiples are to be suppressed in the line-to-line voltages?

- m
_{f}should be odd - m
_{f}should be even - m
_{f}should be an odd multiple of 3 - m
_{f}should be an even multiple of 3