Active energy recovering snubber for the asymmetric inverter

This paper presents a single capacitor active snubber circuit for the asymmetric inverters used to drive switched reluctance motors. The proposed configuration uses the motor coil inductance as an integral component in the snubber process, acting in sequence to ensure the low-loss commutation of each inverter main power device. The two auxiliary snubber switches naturally commutate in ZCS mode. Only one minor change in the inverter firing sequence is required to include the snubber. Initial simulations in AIMSPICE show that the snubber produces significant reduction in commutation losses without affecting the asymmetric inverter operation. A laboratory prototype is undergoing tests to study the complete operating envelope of the modified inverter driving a switched reluctance motor under DTC control.