SiC逆变器在不同开关频率下直流侧EMI滤波器分析

DC side EMI filter analysis based on silicon carbide inverter under different switching frequencies

逆变器工作过程中产生的电磁干扰(EMI)可以通过在电路中加入滤波器的方法使其得到有效的抑制。SiC逆变器相比于普通的Si逆变器可以工作在更高的开关频率,而这将恶化逆变器产生的EMI。本文对比了SiC逆变器工作在不同开关频率即10kHz和40kHz这两种情况下直流侧的EMI,并基于插入损耗和阻抗匹配的原则设计了相应的EMI滤波器。对于40kHz的开关频率,除加入EMI滤波器还使用随机PWM降低了直流侧的EMI,通过改变调制方法和加入滤波器使得逆变器工作在40kHz开关频率下直流侧能够满足相应的电磁干扰标准。

EMI generated by inverters in operation can be effectively suppressed by adding a filter in the circuit.The Silicon Carbide(SiC)inverters can work at a higher switching frequency than the ordinary silicon inverter which will deteriorate the EMI generated by the inverters.The DC side EMI of the SiC inverter is compared at different switching frequencies,10kHz and 40kHz,and corresponding EMI filters based on the principle of insertion loss and impedance matching are analyzed.For the switching frequency of 40kHz,in addition to adding the EMI filter,the random pulse width modulation(RPWM)is used to reduce the EMI on the DC side.In combination with the two methods of changing the modulation method and adding the filter,the DC side EMI of inverter operates at 40kHz switching frequency can fulfill the electromagnetic interference standard.