A Voltage-Edge-Rate-Limiting Soft-Switching Inverter Based on Auxiliary Resonant Pole

To increase switching frequencies while limiting switching losses in voltage-source inverters, power switches have been made significantly faster with achievable switching times now less than 100 ns. However, faster switches generate larger inverter output voltage edge rates (dv/dt) and result in deleterious effects in variable-speed drive systems including transient overvoltages at motor terminals, electromagnetic interference, and bearing failures due to microares. A common approach for limiting peak dvldt involves using a dvldt filter. However, the dv/dt filter introduces extra power losses and increases the overall size and weight of the system. Soft-switching circuits, which were originally developed to reduce switching losses, can help reduce dv/dt, but using soft-switching to accurately control dv/dt has not been fully explored. In this paper, a new soft-switching circuit, entitled the auxiliary resonant soft-edge pole (ARSEP), is set forth. ARSEP improves the available soft-switching circuits so that dvldt can be accurately controlled through the circuit parameter design. An ARSEP inverter prototype was designed, simulated, and constructed to verify its performance and benefits. Compared to a conventional hard-switched inverter with a dv/dt filter, the ARSEP inverter prototype results in a significant reduction in overall power loss, inductor volume, and weight.