Common-mode noise modelling and resonant estimation in a three-phase motor drive system: 9-150 kHz frequency range

This paper presents an equivalent circuit impedance-based estimation method of resonances in a three-phase motor drive system to predict common-mode (CM) noise circulations in 9-150 kHz frequency range, which is not considered so far in electromagnetic interference (EMI) analysis. The paper verifies the presented method by analyzing emission spectrums of CM currents in the three-phase system. The impact of EMI filter, DC-link filter and AC motor models on the generated common mode noise at 9-150 kHz range is also investigated using the predicted equivalent impedance results at the CM voltage source. It is found, there is a high probability to have resonances within 9-150 kHz range due to the components of the drive system. Hence, the work presented is useful to model and predict the possible resonances in the whole drive system that unnecessarily increases the CM noise at this frequency range. The presented estimation method not only enables the ability to early recognition of CM current emissions injected from the drive system to the grid but also supports EMI filter design or modification for 9-150 kHz frequency range. Further, this approach significantly contributes to accelerating the drive products development and entering the market after complying the future standards.