Correct AnswerA. Square wave and unipolar sinusoidal PWM switching schemes
Quick Explanation
Quasi-square-wave operation is produced by combining two square-wave bridge outputs with a controllable phase displacement. Their overlapping portions add while displaced portions cancel, allowing the fundamental output to be adjusted and selected low-order harmonics to be reduced.
Detailed Explanation
Correct Answer
A — Square wave and unipolar sinusoidal PWM switching schemes
Concept and Reasoning
Quasi-square-wave operation is produced by combining two square-wave bridge outputs with a controllable phase displacement. Their overlapping portions add while displaced portions cancel, allowing the fundamental output to be adjusted and selected low-order harmonics to be reduced.
Calculation / Key Relation
vout = vbridge1 − vbridge2 with phase displacement
Exam Takeaway
Voltage cancellation uses phase-shifted square waves.
Common Mistake
Do not confuse quasi-square operation with sinusoidal carrier-based PWM.
