Commutation methods in inverters: Evaluate the statement “All inverters use forced commutation.” Decide whether it is correct, considering different inverter topologies and line conditions.

Introduction / Context:
Inverters convert DC to AC using power switches that must be turned on and off (commutated). The method of turning devices off can be natural (line-commutated) or forced (using auxiliary circuits). This question tests recognition that not all inverter families need forced commutation.

Given Data / Assumptions:

• Older thyristor-based inverters can be line-commutated (natural commutation) when connected to an AC grid.
• Forced commutation uses additional components (capacitors/inductors/auxiliary switches) to remove current from a device.
• Modern self-commutated devices (IGBTs, MOSFETs) turn off via gate control, not forced LC commutation networks.

Concept / Approach:

“All inverters use forced commutation” is overly broad. Line-commutated inverters rely on the AC system voltage zero crossings to naturally commutate thyristors. Voltage-source PWM inverters with IGBTs/MOSFETs are gate-commutated devices; they do not require classical forced commutation circuits used with SCRs.

Step-by-Step Solution:

Verification / Alternative check:

Standard power electronics texts distinguish natural, forced, and self-commutation; gate-turn-off devices eliminate the need for auxiliary commutation circuits.

Why Other Options Are Wrong:

• “True” fails because line-commutated and self-commutated converters exist which do not employ forced commutation.

Common Pitfalls:

Equating “turn-off” with “forced commutation” in all contexts; modern switches implement controlled turn-off internally via gate charge control.

Final Answer:

False