基于PCB罗氏线圈的SiC MOSFET短路保护研究

摘要

The shortage of SiC metallic oxide semiconductor field effect transistor (MOSFET)'s short circuit withstand time increases the difficult of sbort-circuit protection.The traditional desat protection method is prone to cause serious impact to SiC MOSFET as its long blank time and high detection threshold.The function of high frequency alternating current test and the characteristic of sensitive response make printed circuit board (PCB) Rogowski coil suitable for fast short circuit detecting of SiC MOSFET.When short circuit occurs in SiC MOSFET,the PCB Rogowski coil with its compound integration circuit is utilized to extract transient current and give feedback signal to the gate driver that shortens the delay time of short circuit detection.By soft turn-off,the impact of excessive voltage spike caused by high change rate of current is avoided.Experimental results show that,the PCB Rogowski short-circuit detecting method can turn-off SiC MOSFET reliably and rapidly in short circuit occurred.%SiC金属氧化物半导体场效应晶体管(MOSFET)过短的短路承受时间增大了短路保护的难度,传统退饱和法较长的检测时间容易对SiC MOSFET造成严重冲击.印制电路板(PCB)罗氏线圈高带宽交变电流检测及反应灵敏的特性,使其适用于功率器件短路的快速检测.在SiC MOSFET发生短路时,利用PCB罗氏线圈配合复合式积分电路提取瞬态变化电流,进行反馈控制,有效缩短短路保护的延迟时间.通过软关断,减小关断过程中过高的电流变化率导致的过压对SiC MOSFET造成过大的冲击.实验结果表明,采用PCB罗氏线圈电流检测法能在短路发生第一时间迅速可靠地关断SiC MOSFET,实现短路保护.