提升桥式电路中SiC MOSFET关断性能和栅极电压稳定性的有源驱动电路研究

Research on Active Gate Driver for Improving Turn-off Performance and Gate Voltage Stability of SiC MOSFET in Bridge Circuit

碳化硅金属氧化物半导体场效应管(silicon carbide metal oxide semiconductor field effect transistor,SiC MOSFET)以其低开关损耗、高工作频率、高开关速度等优点越来越广泛地应用于各类电力电子变换器。然而,电路中寄生电感的存在、过高的开关频率和速度,会使得SiC MOSFET在关断瞬态产生漏极电压尖峰和振荡,严重情况下可造成雪崩击穿;并且加剧栅极电压的串扰(crosstalk)现象。上述问题不仅对半导体器件的安全运行构成威胁,而且会恶化电力电子变换器的高频电磁干扰问题。为此,文中首先分析SiC MOSFET关断过程瞬态电压尖峰和振荡以及串扰的形成机理,并在此基础上提出一种基于dv/dt检测的提升SiC MOSFET关断性能和栅极电压稳定性的有源驱动电路。该驱动电路通过检测关断过程中漏极电压上升的斜率,在漏极电流下降阶段抬升栅极电压,从而抑制漏极电压尖峰和振荡;在串扰发生阶段构造低阻抗回路来有效抑制栅极的串扰尖峰。实验结果表明,所提有源驱动电路不仅能够有效抑制SiC MOSFET关断过程漏极电压的尖峰和高频振荡,而且能够有效抑制栅极串扰的正负向电压尖峰。因此,所提出的有源驱动电路可以有效抑制电力电子变换器的高频电磁干扰,提升其电磁兼容性能。

Silicon carbide metal oxide semiconductor field effect transistor(SiC MOSFET)has been widely used in various types of power electronic converters because of its low switching loss,high operating frequency,high switching speed and other advantages.However,the existence of parasitic inductance,high switching frequency and speed of SiC MOSFET will cause transient drain voltage spikes and oscillations in the turn-off process,resulting in avalanche breakdown in severe cases,and worsening the crosstalk phenomenon of the gate voltage.These problems not only threaten the safe operation of semiconductor devices,but also worsen the high-frequency electromagnetic interference(EMI)of power electronic converters.Therefore,we firstly analyzed the formation mechanism of transient voltage spikes,oscillations and crosstalk during the turn-off process of SiC MOSFET,then an active gate driver based on dv/dt detection to improve turn-off performance and gate voltage stability was proposed.By detecting the slope of the drain voltage during the turn-off process,the gate voltage was raised to suppress the drain voltage spikes and oscillations;when crosstalk occurs,a low impedance loop was provided to suppress the crosstalk voltage spikes.The experimental results show that the proposed active gate driver can not only effectively suppress the voltage spikes and oscillations during the turn-off process of SiC MOSFET,but also suppress voltage spikes of the crosstalk issues.Thus,the proposed gate driver can effectively suppress the high-frequency EMI and improve the electromagnetic compatibility performance of power electronic converters.