Differential overvoltages and common-mode currents in PWM motor drives: The influence of the cable arrangement on their characteristics

Transient overvoltages at motor terminals and high-frequency common-mode currents in PWM drive systems have been extensively investigated in the last fifteen years. Nevertheless, some issues concerning such quantities still remain unclear. That is the case of the converter-to-motor cabling influence on the intensity of these high-frequency voltages and currents. Filters of different types have been traditionally used to mitigate these undesired phenomena. However, due to their cost, volume and losses, they can´t be considered the ultimate solution of the problem. In this paper, typical industrial cable arrangements will be characterized in terms of the generated transient overvoltages and common-mode currents. It will be shown that variations in the range of 10 to 40 % in the peak values of these quantitites can take place due to different cable disposition. Thus, it can be concluded that special care in the cable installation can lead to significant reduction in these undesired phenomena, which in turn downsizes the required filter.