Utilization of a behavioural model of motor drive systems to predict the conducted emissions

This paper describes the high frequency behavior modeling method of an Adjustable Speed Drive (ASD) that will be used to estimate the conducted emissions. In order to study the influence of various elements of the ASD on the electromagnetic interferences (EMI) level, it is necessary to use a precise model of the PWM inverter, energy cable and AC motor which take into account various phenomena that appear when the frequency increases. A model of the shielded 4-wire energy cable that taking into account of the dissymmetry structure is proposed and validated in the frequency domain for two different lengths. The obtained high frequency ASD model is used to estimate the common mode conducted emissions on all inverter functioning period. In this study, PSPICE software is used to simulate the ASD in the time domain. The comparison of measurement and simulation results of conducted emissions (with LISN) shows the good compromise between the simulation duration and accuracy of the results.