An auxiliary zero state synthesizer to reduce common mode voltage in three-phase inverters

The common mode voltage produced by the modulation of three-phase power inverters creates a significant amount of common mode conducted current in motor drives. As an alternative to inserting a large common mode choke to attenuate this common mode current, a modification to the inverter topology and the modulation strategy is proposed that can eliminate zero state components in the common mode voltage produced by the inverter. With the proposed modification, it is observed that the inverter generates substantially low common mode voltage, thereby resulting in the reduction of common mode current by several orders of magnitude. The topological structure, operating principles and performance characteristics are presented. A comparative evaluation of various alternatives studied in the literature to mitigate electromagnetic interference is also presented in the paper.