An Energy Recovery Scheme for RCD Snubber in the Series Configuration of IGBTs

This paper presents an energy recovery scheme for traditional Resistor-Capacitor-Diode (RCD) snubber in the series-connected configuration of IGBTs. In the series configuration of IGBTs, an RCD snubber is used in parallel to each IGBT to provide a safe operating condition for the IGBTs. In the proposed scheme, by using interconnection diodes, the capacitors of the snubbers are parallelized in the on-state of the IGBTs. Thus, the stored energies in the snubber capacitors are lumped together and transferred to the DC link by using a transformer and a resonant circuit. By using the proposed method, the capacitor of the snubber can have a higher value. A higher value of the snubber capacitance improves voltage sharing of the IGBTs and reduces the turn-off switching power losses of the IGBTs. The proposed scheme is simulated for a case study using PSPICE software and tested through an experimental setup. Simulation and experimental results imply the proper performance of the proposed scheme.