An Active Zero-State Switch (AZS) for Commonmode Voltage Reduction in Voltage Source Inverter (VSI) Drives

Common-mode voltage produced by voltage source inverters is of great concern in motor drives because significant amount of common-mode conducted/bearing current is induced and interferes with system operation. As an alternative to inserting bulky passive filters to attenuate common- mode current, a new topology active zero-state switch (AZS) is proposed. Minor adjustment to standard space vector pulse width modulation is also made to realize the proposed scheme and achieve reduced common-mode voltage. The new topology and adjusted modulation scheme are shown to effectively reduce common-mode voltage in a standard commercial voltage source inverter.