Analysis and Control of Soft-Commutation of Inverter at Small Residual Voltage with Benign DV/DT and Integrated Converter Module

A negative-bus auxiliary resonant circuit (NBARC) and control for soft-commutation at small residual terminal voltages of the IPMs / inverters is presented for benign DV/DT output waves and better electromagnetic compatibility. For a practical circuit design, the NBARC is proposed to control the main circuit commutation at low residual voltages, rather than a perfectly zero voltage, resulting in a simplified implementation and reduced cost. The effects of non-ideal commutation conditions at low residual voltages are analyzed and the impacts on the power devices in an IPM are briefly discussed. Experimental results verify our circuit analysis and implementation. The auxiliary switching circuit can be designed compactly and its integration with an integrated IGBT module is further highlighted.