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PWM Inverters MCQs

Practice PWM Inverters MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1
Power ElectronicsPWM Inverters

Sinusoidal PWM in an inverter is commonly obtained by comparing a low-frequency sinusoidal reference with a?

  • AHigh-frequency triangular carrier
  • BDC resistance
  • CSquare-wave load current only
  • DMechanical timing disk
Report an error
Correct Answer: A. High-frequency triangular carrier
Explanation: SPWM compares a sinusoidal modulating/reference signal with a higher-frequency triangular carrier to determine switching instants.
Reference: Standard power electronics: pwm inverters
Question 2
Power ElectronicsPWM Inverters

In sinusoidal PWM, increasing the carrier frequency while keeping the fundamental reference frequency fixed generally moves dominant switching harmonics?

  • ATo higher frequencies
  • BTo DC
  • CExactly onto the fundamental
  • DTo zero frequency
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Correct Answer: A. To higher frequencies
Explanation: Higher carrier frequency shifts switching-related harmonic groups upward, which can simplify output filtering at the cost of higher switching losses.
Reference: Standard power electronics: pwm inverters
Question 3
Power ElectronicsPWM Inverters

In sinusoidal PWM, the amplitude modulation index in the linear region is commonly the ratio of?

  • AReference sine amplitude to carrier amplitude
  • BCarrier frequency to reference frequency
  • CDC-link voltage to load current
  • DSwitching loss to conduction loss
Report an error
Correct Answer: A. Reference sine amplitude to carrier amplitude
Explanation: For carrier-based SPWM, amplitude modulation index ma is the peak reference/modulating signal divided by the peak carrier signal.
Reference: Standard power electronics: pwm inverters
Question 4
Power ElectronicsPWM Inverters

In sinusoidal PWM, the frequency modulation ratio is commonly defined as?

  • ACarrier frequency divided by reference frequency
  • BReference amplitude divided by carrier amplitude
  • COutput voltage divided by input voltage
  • DLoad current divided by switch current
Report an error
Correct Answer: A. Carrier frequency divided by reference frequency
Explanation: mf=fc/fm, where fc is carrier frequency and fm is the desired fundamental/reference frequency.
Reference: Standard power electronics: pwm inverters
Question 5
Power ElectronicsPWM Inverters

An output filter at a PWM inverter is mainly used to?

  • AAttenuate switching-frequency harmonics
  • BIncrease semiconductor layer count
  • CGenerate gate pulses
  • DEliminate the DC source
Report an error
Correct Answer: A. Attenuate switching-frequency harmonics
Explanation: The filter passes the desired low-frequency fundamental while reducing high-frequency switching components.
Reference: Standard power electronics: pwm inverters