Common-Mode Voltage Cancellation in PWM Motor Drives With Balanced Inverter Topology

This paper proposes a balanced inverter topology for canceling the common-mode (CM) voltage of motor drives, and thus reducing or eliminating the ground leakage current, bearing current, and CM electromagnetic interference. The proposed topology splits one of the switches on each phase-leg of a conventional inverter into two half-voltage rated switches, and creates two complementary sets of balanced three phase output voltages, whose CM voltages cancel each other in the driven motor. The balanced inverter topology does not involve filter components, modification of the modulation strategy, or increase of the total device rating. Theoretical analysis and testing results are presented to verify this concept.