Reduction of conducted emissions and motor bearing currents in current source PWM inverter drives

EMC issues have been increasingly discussed. In adjustable speed PWM AC drives problems occur due to leakage currents, i.e. common mode currents resulting from the high motor voltage du/dt values versus the ground. These currents flow through the parasitic capacitance of the motor cable and the motor windings. In this paper an innovative low cost solution to mitigate common mode currents in a PWM current source inverter is proposed. The results are verified by Pspice(R) simulations.