Cascaded Snubber Scheme Using Flyback Type Transformer for 10kV IGCT Applications

IGCT semiconductor is the best candidate to expand the power and voltage rating of future wind turbine systems. IGCT-based converters need snubber and RCD clamp circuit to decay the sharpness of current and voltage stress across IGCT semiconductor at the on and off time respectively. Such a clamp circuit not only need complex IGCT stack design but also has negative impact on overall system loss of converters. In response, this paper suggests a version of flyback clamp snubber comprising cascaded flyback transformers which limit the rate of current rise sequentially. The cascaded flyback clamp snubber meets all of the IGCTs requirements at the on and off time but it consumes significantly lower power. The benefit of cascaded type over basic flyback clamp snubber is the perfect voltage distribution over 10kV SiC clamp diodes. These diodes recover the magnetizing energy of flyback transformer in to the DC-link unit.10kV IGCT and related diode have been used for simulation and experiment using RCD and flyback clamp snubber circuits to prove the advantages of cascaded version.