Switched-capacitor bi-directional converter performance comparison with and without quasi-resonant zero-current switching

The proposed quasi-resonant (QR) zero-current switching (ZCS) switched-capacitor (SC) converter is a new type of bi-directional power flow control conversion scheme. This device provides voltage conversion ratios from 2 against 1/2 (double-mode/half-mode) to n against 1/n (n-mode/1/n-mode) by adding a different number of SCs and power multi-oxide-semiconductor field-effect-transistor (MOSFET) switches with a small series-connected resonant inductor for forward and reverse schemes. The proposed QR SC converter presents low current stress and balanced resonant current advantages. The operating principle and theoretical analysis of the proposed bi-directional power conversion scheme are described in detail with circuit model analysis. The proposed device is compared with the conventional SC converter. Simulations and experimental verification are carried out to verify and compare the proposed QR ZCS SC bi-directional converter performance with the conventional device. At maximum efficiency, the proposed device can achieve 96% and 93% for the forward and reverse power flow control schemes, respectively.