Conducted EMI in PWM inverter for household electric appliance

This paper presents the mitigation effort of the conducted electromagnetic interference (EMI) in the pulsewidth-modulation (PWM) inverter for household electric appliances. First, noise sources in the PWM inverter are investigated to get an understanding of their characteristics, and the propagation of the conducted EMI is described. Next, input filters are added to: suppress it. With changing filter stages, the conducted EMI spectra are measured to identify their effect. The common-mode EMI spectrum is extracted to separate the effect of the common-mode filter and to identify the dominant noise source. A new active common-mode EMI filter is proposed to give better attenuation of the common-mode noise and to enhance the performance of additional passive filters. An efficient way to design of input filter is discussed based on the measurement results.