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

Abstract

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 of the proposed method, the capacitor of the snubber can have a higher value. Higher value of the snubber capacitance improve voltage sharing of the IGBTs and reduce 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.

Voltage Balancing of Series-Connected SiC mosfets With Adaptive-Impedance Self-Powered Gate Drivers

“…Since the closed-loop control is applied, the stability problem is introduced as well. As analyzed in Section IV, once the converter is built, the criterion for a stable system is obtained according to (21) and no experimental identification is required, which is superior than existing active delay control strategies. The hardware parameters have already been provided in Table I, and fs = 10 kHz, i D = 15 A, T s = 0.2 s (with the diode-capacitor structure tolerating the voltage unbalancing temporarily, the controller calculation burden can be eased by choosing a relatively large T s ) are known in advance, hence, the appropriate range of K p and K i can be obtained.…”