Power Electronic Converters — MCQs – EE

1. What is a power electronic converter?
(A) A device that converts electrical energy from one form to another
(B) A data communication device
(C) A frequency measuring instrument
(D) A digital logic circuit

2. A rectifier converts:
(A) AC to DC
(B) DC to AC
(C) DC to DC
(D) AC to AC

3. An inverter converts:
(A) DC to AC
(B) AC to DC
(C) AC to AC
(D) DC to DC

4. A chopper is a type of converter that converts:
(A) DC to variable DC
(B) AC to DC
(C) DC to AC
(D) AC to variable AC

5. An AC voltage controller is used to:
(A) Control AC voltage applied to a load
(B) Convert DC to AC
(C) Step up DC voltage
(D) Control DC current

6. The main device used in modern power converters is:
(A) IGBT (Insulated Gate Bipolar Transistor)
(B) Resistor
(C) Diode only
(D) Transformer

7. Which converter uses SCRs as the main switching devices?
(A) Line-commutated converter
(B) PWM inverter
(C) Resonant converter
(D) Cycloconverter

8. A cycloconverter converts:
(A) AC of one frequency to AC of another frequency
(B) DC to DC
(C) DC to AC
(D) AC to DC

9. The output voltage of a DC chopper depends on:
(A) Duty cycle of the switching device
(B) Load current
(C) Input frequency
(D) Inductor value

10. Inverters are widely used in:
(A) Uninterruptible Power Supplies (UPS)
(B) Transformers
(C) Rectifiers
(D) Filters

11. A buck converter is a DC-DC converter that:
(A) Steps down voltage
(B) Steps up voltage
(C) Converts AC to DC
(D) Converts DC to AC

12. A boost converter is used to:
(A) Step up DC voltage
(B) Step down DC voltage
(C) Convert DC to AC
(D) Control AC frequency

13. A buck-boost converter can:
(A) Step up or step down DC voltage
(B) Convert AC to DC
(C) Generate AC from DC
(D) Control current only

14. The function of a freewheeling diode in a converter is to:
(A) Provide a path for current during switch-off period
(B) Increase switching frequency
(C) Decrease input voltage
(D) Amplify current

15. A PWM inverter controls the output voltage by:
(A) Varying pulse width of the output waveform
(B) Changing input voltage
(C) Using a transformer
(D) Changing the duty ratio of the AC signal

16. Which type of converter is used for regenerative braking in motors?
(A) Bidirectional converter
(B) Unidirectional converter
(C) Inverter
(D) Transformer

17. The efficiency of a power converter is generally:
(A) Very high (above 90%)
(B) Very low (below 50%)
(C) Constant at 60%
(D) Unpredictable

18. Which device provides electrical isolation in converters?
(A) Transformer
(B) Diode
(C) Capacitor
(D) Inductor

19. The output of an uncontrolled rectifier depends on:
(A) Input AC voltage
(B) Gate signal timing
(C) Load resistance
(D) Supply frequency only

20. A controlled rectifier uses:
(A) SCRs or thyristors
(B) Diodes only
(C) Transistors only
(D) Relays

21. A single-phase half-wave rectifier requires:
(A) One diode
(B) Two diodes
(C) Four diodes
(D) Six diodes

22. A full-wave rectifier requires:
(A) Two or four diodes
(B) One diode
(C) Three diodes
(D) Six transistors

23. A three-phase bridge converter typically uses:
(A) Six SCRs or diodes
(B) Two transistors
(C) Four capacitors
(D) Three transformers

24. In AC voltage controllers, the load voltage is controlled by:
(A) Firing angle control of SCRs
(B) Input frequency variation
(C) Output filtering
(D) Inductor resistance

25. A multilevel inverter is designed to:
(A) Reduce harmonic distortion
(B) Increase switching losses
(C) Lower efficiency
(D) Reduce input current

26. Which converter topology is commonly used in solar power systems?
(A) DC-DC boost converter
(B) AC voltage regulator
(C) DC chopper
(D) Cycloconverter

27. In power converters, snubber circuits are used to:
(A) Protect switching devices from voltage spikes
(B) Filter input noise
(C) Step down voltage
(D) Improve load regulation

28. A soft-start circuit in converters helps in:
(A) Gradually increasing voltage to prevent inrush current
(B) Immediate full-power start
(C) Rapid switching
(D) Reducing power factor

29. The switching frequency of a converter determines:
(A) Size of passive components and efficiency
(B) Output voltage ripple only
(C) Input power only
(D) Load type

30. The main advantage of power electronic converters in industry is:
(A) High efficiency and precise control of power flow
(B) High power loss
(C) Simple mechanical design only
(D) Low voltage regulation