Capacitor timing in an auxiliary-commutated (Class C) chopper In an auxiliary commutated chopper, how do the charging and discharging times of the commutation capacitor depend on operating conditions?

Introduction / Context:
Auxiliary (Class C) choppers use a commutation capacitor and inductor to turn off the main switch. The timing of charge and discharge influences maximum switching frequency and reliability.

Given Data / Assumptions:

• Auxiliary commutation network (C and L) is used.
• Main switch carries load current I_load when turned off by auxiliary path.
• Idealized components for reasoning.

Concept / Approach:
To commutate the main device, the resonant current through the auxiliary path must exceed the instantaneous load current. Thus, the discharge of the capacitor (which creates the reverse current) and the required energy in the commutation network depend on I_load at the commutation instant, altering effective timing.

Step-by-Step Solution:
Set resonant current i_res(t) relative to I_load.Ensure i_res_peak ≥ I_load to force current reversal in main device.Higher I_load demands more charge/discharge excursion → timing depends on load current.

Verification / Alternative check:
Waveforms in standard texts show commutation interval stretching with higher load current due to greater reverse current requirement.

Why Other Options Are Wrong:
Constant/Only source/Only inductor: Oversimplify; load current at commutation materially affects capacitor current and timing.

Common Pitfalls:
Designing the commutation network only for nominal current; peak-load conditions can prolong or even fail commutation if underdesigned.

Final Answer:
depend on load current