基于MOSFET的串联谐振双有源桥死区振荡机理分析及抑制

Mechanism Analysis and Suppression of Oscillation in Dead Time of Series Resonant Dual Active Bridge Based on MOSFET

基于MOSFET的串联谐振双有源桥(DAB)变换器可同时实现所有功率器件的零电压开通(ZVS)和零电流关断(ZCS),具有效率高的优点,被广泛应用于电力电子变压器(PET)隔离DC-DC环节。然而,在采用隔离变压器的DAB中,由于MOSFET寄生电容的存在,在死区时间内器件寄生电容与隔离变压器漏感会产生高频振荡,增加了通态损耗。该文建立死区时间内串联谐振DAB的等效电路,分析死区时间内高频振荡电流幅值与关断时刻电流的数学关系。为抑制高频振荡,提出基于开关频率微调的振荡抑制方法。实验结果表明了理论分析的正确性和高频振荡抑制方法的有效性。

The series resonant dual active bridge(DAB)converter based on MOSFET can realize zero voltage switching(ZVS)and zero current switching(ZCS)of all power devices at the same time.It has high efficiency and is widely used in isolated DC-DC stage of power electronics transformer(PET).However,in DAB with isolation transformer,due to the existence of parasitic capacitance of MOSFET,the parasitic capacitance and leakage inductance of isolation transformer will produce high frequency oscillation in the dead time,which will increase the conduction loss.In this paper,the equivalent circuit of series resonant DAB in dead time is established.The mathematical relationship between the amplitude of high frequency oscillation current and the current at turn off time is analyzed.In order to suppress high frequency oscillation,an oscillation suppression method based on switch frequency fine tuning is proposed.The experimental results show that the theoretical analysis is correct and the high frequency oscillation suppression method is effective.