Impact of diode-rectifier on EMC-noise propagation and filter design in AC-fed motor drives

It is well-known that the active switching of the DC-voltage inside the inverter is the dominant source of high frequency noise. In contrast, the impact of the diode rectifier is often believed to be small due to its low-frequency commutation without active switching. In this work we show that the diode rectifier has in fact a big impact on the noise propagation and therefore also on the EMC-filter design since it introduces a strong coupling between common mode and differential mode noise. We present a filter design workflow that accounts for the mode mixing by the diode rectifier.