Chopper commutation principle A DC–DC chopper cannot be line-commutated (natural commutation by AC line zero crossings). State whether this statement is true or false.

Introduction / Context:Commutation refers to how a power switch turns off. “Line commutation” uses the alternating supply voltage/current zero crossing, typical in AC line-commutated rectifiers. DC–DC choppers, however, operate from a DC source, so there is no natural line zero crossing to effect turn-off.

Given Data / Assumptions:

• Input source for a chopper is DC.
• No inherent AC zero crossing is present.
• Switches are thyristors or self-commutated devices (IGBT/MOSFET) with forced turn-off control.

Concept / Approach:

Because the input is DC, a thyristor in a chopper cannot rely on line commutation. Either self-commutated devices (MOSFETs/IGBTs) are used, which turn off via gate control, or additional commutation circuits are provided to force current to zero (auxiliary/forced commutation for thyristor-based choppers).

Step-by-Step Solution:

Verification / Alternative check:

Power electronics texts classify choppers under forced/self-commutated converters, unlike LCC rectifiers which are line-commutated.

Why Other Options Are Wrong:

“False” contradicts the DC nature; qualifiers about class or frequency do not create AC zero crossings, so they are incorrect.

Common Pitfalls:

Confusing inverter/rectifier line commutation with DC chopper operation; assuming any oscillatory commutation equals line commutation.

Final Answer:

True