Time domain models of the EMI sources in the variable speed drives

This paper deals with conducted electromagnetic interferences (EMI) generated by the power static converter used in the adjustable speed drive (ASD) applications. To study, by simulation, the conducted emissions induced by the power converter with reasonable calculation duration, a simple high frequency model of noise sources is necessary. In this paper, EMI sources of the PWM inverter are modeled using an equivalent current or voltage generators in the time domain. The simulation results are compared with measurement data in the frequency domain. In order to validate the proposed model in the ASD system, it is necessary to use a precise model of energy cable and AC motor which take into account various phenomena which appear when the frequency increases. A model of the shielded 4-wire energy cable that taking into account of the dissymmetry structure is used. The obtained high frequency ASD model is used to estimate the conducted emissions over all inverter functioning period.