AC-drives with parallel motor cables using state-of-the-art silicon devices

A long cable between an electrical motor and a PWM voltage-source AC-drive is typical in the Heating, Ventilation and Air-conditioning (HVAC) segment, especially stressing the drive in the low-power range. Sometimes paralleled motor cables are desired for powering multiple small motors by one larger AC-drive, which may take the stress to an undesirable level. By practical test examples, this stress is quantified in this paper, and recommendations for best practice in the field are given minimizing problems.