Impact of application of SiC devices in motor drive on EMI

This paper gives a study on the EMI noise problem of motor drives, especially the impact of application of fast-switching SiC devices. First, the noise source model has been analyzed and the two major factors: device switching action and inverter switching frequency have been claimed. Device switching performance analysis has been done to show that the fast switching speed will generate bigger EMI noise at EMI high frequency range, ringing in the device switching can worsen the EMI noise near the ringing frequency, too. In the meantime, increasing of switching frequency of inverter can bring bigger EMI noise at EMI low frequency range. With variable switching frequency, EMI peak value can be reduced for the motor drive. But the average EMI of SiC motor drive is still bigger than Si motor drive which is with lower average switching frequency. The analysis has been supported by experimental results. The challenge of EMI should be considered for motor drive with SiC devices for advanced applications.