Motor cable as an origin of supplementary conducted EMI emission of ASD

Investigation of conducted electromagnetic interference (EMI) in AC motor drives fed by a pulse width modulated (PWM) voltage converters requires that converters´, motor windings´ and feeding cables´ parasitic capacitances have to be taken into account. Motor voltage transients and related EMI emission are substantially correlated with resonance effects occurring in load circuits. Frequency impedance characteristics analysis allows for identification and determination of resonance frequency ranges which have the foremost contribution to voltage ringing phenomena. The paper presents a method of analysis of AC motor windings parasitic capacitances with the particular account of cable influence on it´s broadband overall performance. The proposed circuit model allows for analysis of influence of cable parameters on conducted EMI emission of AC motor drives.