Study of the characteristics and suppression of EMI of inverter with SiC and Si devices

The paper systematically studies the impacts of two major factors: device switching actions and inverter switching frequency on the whole EMI spectrum. Several powerful experimental results of electromagnetic interference(EMI) in voltage source inverter(VSI) with SiC and Si devices are provided. As far as the influence of switching actions is concerned: faster switching speed will generate higher EMI noise levels in the high frequency range, and ringing in the device switching will also make the EMI noise near the ringing frequency range worse. In the meantime, increasing of the switching frequency of the inverter will result in a higher EMI noise peak for the whole EMI spectrum. In order to suppress the EMI noise of the converter to meet standards, Random PWM(RPWM) and EMI filters are adopted. With RPWM, the EMI current can drop a few more dB than that with SVPWM, which makes the filter work better. Also, as extra attenuation can be provided, it provides the benefit of reducing the weight and volume of the inductor of the filter. Therefore, the combination of an advanced modulation strategy and EMI filter is proposed for suppressing of EMI noise in an inverter.