Power electronics and machine modeling – MCQs – EE

1. Power electronics deals with:
(A) Control of electrical energy using electronic devices
(B) Mechanical energy conversion
(C) Thermal energy analysis
(D) Software programming only

2. The main function of a rectifier is to:
(A) Convert AC to DC
(B) Convert DC to AC
(C) Step up voltage
(D) Step down voltage

3. A chopper is used to:
(A) Convert DC to DC at different voltage levels
(B) Convert AC to DC
(C) Convert DC to AC
(D) Measure current

4. An inverter is used to:
(A) Convert DC to AC
(B) Convert AC to DC
(C) Step up voltage only
(D) Step down voltage only

5. A thyristor is:
(A) A controllable semiconductor switch
(B) A mechanical switch
(C) A transformer
(D) A capacitor

6. The main characteristic of a MOSFET is:
(A) Voltage-controlled device
(B) Current-controlled device
(C) High power loss
(D) Mechanical switching

7. IGBT is preferred for:
(A) High voltage and high current applications
(B) Low voltage applications only
(C) Small signal circuits
(D) Mechanical control

8. In power electronics, switching devices are used to:
(A) Control voltage and current
(B) Perform integration
(C) Perform differentiation
(D) Measure resistance

9. Pulse Width Modulation (PWM) is used to:
(A) Control output voltage of inverters and choppers
(B) Measure frequency
(C) Convert AC to DC
(D) Step up voltage only

10. Machine modeling in MATLAB/Simulink is used to:
(A) Simulate performance of electrical machines
(B) Measure resistance
(C) Perform mechanical design
(D) Analyze software only

11. Synchronous machines have:
(A) Constant speed operation
(B) Variable speed only
(C) DC operation only
(D) Step-down transformers

12. Asynchronous machines are also called:
(A) Induction machines
(B) Synchronous machines
(C) DC machines
(D) Servo motors

13. In modeling DC motors, the main equations include:
(A) Voltage, current, and torque relationships
(B) Only voltage equations
(C) Only mechanical equations
(D) Thermal equations only

14. The main purpose of machine modeling is to:
(A) Predict dynamic behavior
(B) Measure physical parameters directly
(C) Control the circuit only
(D) Reduce mechanical losses

15. MATLAB/Simulink supports:
(A) Modeling DC, synchronous, and induction machines
(B) Only DC machines
(C) Only synchronous machines
(D) Only mechanical systems

16. Field-oriented control (FOC) is used for:
(A) Vector control of AC machines
(B) Step-down transformers
(C) Rectifier design
(D) Frequency measurement only

17. Power electronic converters can affect machines by:
(A) Modifying voltage and current waveforms
(B) Only measuring current
(C) Reducing resistance
(D) Cooling the machine

18. Simulation of power electronic circuits allows:
(A) Testing system behavior before hardware implementation
(B) Real-time measurements only
(C) Physical construction only
(D) Software programming only

19. Inverter-fed induction motors can achieve:
(A) Variable speed operation
(B) Constant speed only
(C) DC operation
(D) Only step-down voltage

20. MATLAB toolboxes for power electronics include:
(A) Simscape Electrical
(B) Control System Toolbox
(C) Signal Processing Toolbox
(D) Image Processing Toolbox

21. Modeling of transformers includes:
(A) Primary and secondary winding equations
(B) Only resistance
(C) Only flux
(D) Only current measurements

22. In power electronics, switching losses occur due to:
(A) On-off transitions of devices
(B) Continuous conduction only
(C) Resistance measurement
(D) Inductance only

23. Conduction losses occur due to:
(A) Current flowing through semiconductor devices
(B) Voltage measurement
(C) Transformer flux only
(D) Mechanical friction

24. MATLAB simulation helps in:
(A) Optimizing control strategies
(B) Hardware construction
(C) Only measuring voltages
(D) Mechanical design only

25. Vector control allows:
(A) Decoupled control of torque and flux in AC machines
(B) Only speed measurement
(C) Voltage scaling
(D) Only DC operation

26. Space vector PWM is used for:
(A) Efficient control of three-phase inverters
(B) Rectifier operation
(C) DC motor only
(D) Frequency measurement

27. MATLAB/Simulink blocks for power electronics include:
(A) IGBT, MOSFET, diode, converter blocks
(B) Only resistor blocks
(C) Only transformer blocks
(D) Only constant blocks

28. Induction motor modeling includes:
(A) Rotor and stator voltage and flux equations
(B) Only torque measurement
(C) Only voltage equations
(D) Only current measurement

29. Synchronous machine modeling involves:
(A) Rotor excitation and stator voltage equations
(B) Only stator resistance
(C) Only mechanical equations
(D) Only torque measurement

30. The main advantage of simulation in power electronics and machine modeling is:
(A) Safe and cost-effective testing of different scenarios
(B) Eliminates need for hardware
(C) Reduces computation only
(D) Only improves plotting