Resonance suppression control for flying capacitor type bidirectional three-level chopper circuit

Recent years, high-voltage and large capacity dc-dc converters are vigorously studied for various dc applications. One of them is the flying capacitor type multi-level chopper circuit (FCC) that realizes high boost/buck ratio conversion and downsizes an inductor. However, it has the problem of transient oscillation due to resonance caused by the inductor and output capacitor when operating conditions change, and thus excessive voltage and current may damage circuit components. To suppress the transient oscillation, a control scheme based on state feedback control is proposed for the FCC in this paper. The effectiveness of the proposed control is demonstrated through the circuit simulations and experiments using a three-level scale-down model under both buck and boost modes.