I was wondering what would happen to the steady state output voltages and currents of the Buck, Boost and the Buck-Boost converters, working in
1 - Continuous conduction mode (CCM),
2 - Discontinuous conduction mode(DCM),
when suddenly their load gets disconnected due to some fault. All three converters are assumed to be in ideal conditions with all ideal components. The load (purely resistive) in all three is connected across an output filter capacitor. The switches in all three are controlled by PWM scheme.
Further assume that:
All converters are having an Input of say 20V, and a fixed duty ratio of 0.8. The resistive load is of say 20 ohms and the switching frequency is 100 kHz.
My thinking in the case of CCM is:
- For Buck converter, the capacitor will charge to full voltage and then no current will flow.
- For Boost, the inductor will keep giving its energy to the output capacitor and after a certain point when voltage limits of the capacitor exceed, burnout of switch or diode may occur.
- For Buck-Boost, similar to buck or boost scenario depending upon the duty ratio.
I have no idea about what might happen in DCM.
For reference the schematics of the three choppers are given below:-
So, please answer, review and help!