Boost电路开关瞬间电压尖峰产生机理及抑制方法

Mechanism of voltage spike production during switching transients and its suppression methods in Boost converter

Boost变换器常用作两级式逆变器的前级升压电路,由于电路中寄生参数的存在,开关瞬间输出电压叠加有瞬态尖峰,降低了波形质量,甚至影响逆变器的正常工作。为了抑制直流环节电压尖峰,研究了Boost电路开关瞬态过程,针对瞬态电路开关特性和开关器件工作状态,建立了基于金属氧化物半导体场效应晶体管(MOSFET)和肖特基二极管(SBD)的换流单元的解析模型,进一步分析了不同寄生参数对开关瞬态电流特性的影响,以及导致电压尖峰的机理等。仿真分析了寄生参数与输出电压尖峰大小的关系,提出了"减缓开关速度"和"降低输出端寄生电感"2种从源头抑制输出电压尖峰的方法。仿真和实验表明,这2种抑制方法能够有效减小电压尖峰,提高Boost电路的输出电压性能。

Boost converter is often used as the pre-stage circuit in double-stage inverter.Because of the existence of parasitic parameters in the circuit,the output voltage will be superimposed with transient spikes,which reduces the waveform quality and even affects the operation of inverter.In order to suppress the voltage spikes,the switching transient of Boost converter is studied.Aimed at the switching characteristics of transient circuit and the operation status of switching devices,an analytical model of commutation unit based on metaloxide-semiconductor field-effect transistor(MOSFET)and Schottky barrier diode(SBD)is established,and the influence of parasitic parameters on the current characteristics during switching transient,as well as the mechanism of causing voltage spikes,is analyzed.The relationships between the parasitic parameters and the output voltage spikes are analyzed and compared by simulation,and two methods are proposed to suppress the output voltage spikes,which are"slowing down the switching speed"and"reducing the output terminal parasitic inductance".The validity of these two methods to reduce voltage spikes and improve output voltage performance of Boost converters has been verified by simulation and experiments.