Analysis and Mitigation of Voltage Overshoot in Auxiliary Switches of a Si-IGBT ARCP Inverter

This paper analyzes the voltage overshoot phenomenon on auxiliary switches in Auxiliary Resonant Commutated Pole (ARCP) inverters and proposes a saturable inductor-based method to suppress the voltage overshoot. The basic operating principle of the ARCP inverter is revised, and a circuit model was presented to analyze the cause of auxiliary switches' voltage overshoot. It was found that the high di/dt during the diode reverse recovery current extinguishing process induces unwanted voltage on both the resonant inductor (L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> ) and parasitic inductances, and this is the main contribution to the excessive voltage. Several possible solutions are discussed, and a proper method is proposed. One of the proposed methods replaces the fixed-resonant inductor with a saturable-core inductor presenting high inductance at near zero current. The core's selective-high-inductance reduces the reverse recovery current and the di/dt, and its high-frequency resistance help suppress the overvoltage and mitigate the oscillation. An ARCP inverter (ARCPI) single-phase prototype has been developed to observe and understand the overvoltage phenomenon and the effectiveness of the mitigation method.