Inductor-current oscillation in a 4-phase Series-Capacitor Buck (SCBC) with outer voltage-loop PID

I built a 4-phase interleaved Series-Capacitor Buck Converter (SCBC) in Simulink. With a voltage-mode PID driving PWM duty, I see a steady-state oscillation in inductor current. Minimal model and plots attached.

[John D'Errico]

And so? We are all happy that you built something. If you have a question at some point, then ask it.

Answer 1

[Sabin]

Steady-state oscillations in inductor current are mainly due to the phase-shifted switching (interleaving), LC resonance involving the series capacitor and inductors, and possibly suboptimal PID tuning in the voltage-mode control loop. Interleaving phases reduces input/output current ripple. However, the phase-shifted operation causes each inductor current to have a periodic ripple.