移相全桥电路整流二极管电压振荡原理与抑制

Research on Voltage Oscillation and Suppression of Rectifier Diode in Phase-shifted Full-bridge Circuit

在大功率场合中,移相全桥变换器应用十分广泛。该变换器可以利用谐振电感与开关管的寄生电容发生谐振来实现开关管的零电压开关(ZVS)。鉴于移相全桥主电路拓扑的特点,在考虑变压器漏感和整流二极管寄生参数的基础上,建立了基于移相全桥变换器变压器次级整流桥换流时的暂态等效电路模型,并详细分析变压器次级整流桥寄生振荡的产生机理。介绍了几种常用抑制整流二极管电压振荡的方法,并利用PSIM软件进行了仿真对比验证。实验表明,在大功率场合,移相全桥变换器中采用初级二极管箝位电路加次级RCD吸收电路,能极大抑制变压器整流二极管电压尖峰和电压振荡。

Phase-shifted full-bridge converter is widely used in high power applications.The converter can realize the zero voltage switching(ZVS)by resonance between the resonant inductance and the parasitic capacitance of the diode.Considering the characteristics of the main circuit of phase-shifted full-bridge,the equivalent model of converter transformer secondary rectifier bridge commutation is established and the generating mechanism of parasitic oscillation of output rectifier bridge is also analyzed.Several methods to suppress the voltage oscillation of rectifying diodes are introduced,their advantages and disadvantages are analyzed,and simulation verification is conducted by the PSIM software.The experiments show that the diode voltage spike and voltage oscillation can be greatly suppressed when the diode clamp circuit of the primary side and the RCD absorbing circuit of the secondary side are used in the phaseshifted full-bridge converter in high power applications.