Character Research of Common-mode Voltage in PWM-driven Motor System

The time-domain and frequency-domain character of common-mode voltage in three-phase two level PWM-driven motor system is analyzed based on the detailed deduction of common-mode voltage expression in DC side and AC side. And the changes of common-mode voltage in motor side when using long cable between converter and motor is analyzed also. Theoretical predictions are verified using simulation with Saber soft, and conclusions are proved with experimental tests.