Improved Phase Shift Control for SiC-MOSFET Based Resonant Switched-Capacitor Converter with Parasitics Consideration

In this article, the resonant switched-capacitor converter (RSCC) is applied to the auxiliary power system of electric locomotive to improve its efficiency and power density. Phase shift control is generally applied to the RSCC for voltage regulation. But the dead time and parasitic parameters impose the negative effects on the switching transit, the resulted hard-switching process may cause extra switching loss. An optimized soft- switching realized method is proposed under phase shift control. First, transient analysis of resonance is carried out by state trajectory, and steady-state characteristics are discussed. Then, the influence of parasitic parameters on resonant current and output power is discussed. Moreover, the dead-time effect and soft-switching condition are analyzed; therefore, a high-efficiency control strategy with zero-voltage switching is proposed. Experimental results show that the proposed optimization control strategy can improve the efficiency up to 99.4%.