Low Dissipative Snubber Using Flyback-Type Transformer for 10 kV IGCT in 7 MW Wind Turbine Systems

10 kV integrated gate-commutated thyristor (IGCT) has been recently developed and has the potential to push wind turbine systems to higher power and voltage rating. Converters employing IGCTs need snubber and over-voltage protection circuit to limit the rate of current's rising and peak over voltage across IGCT during turn-on and -off state, respectively. The conventional resistor-capacitor-diode (RCD) snubber which is used in such power converter dissipates a significant amount of power. In order to reduce the amount of energy lost by the conventional RCD snubber, this paper proposes flyback-type snubber. Flyback-type snubber not only meets all of the IGCTs characteristics during on- and off-state but also significantly saves the power loss. The proposed flyback-type snubber can save up to 73% of the loss in conventional di/dt snubber circuit according to the PLECS magnetic simulation of three-level neutral point clamped grid side converter. The experiments are performed using IGCT stack. Flyback transformer yields the effectiveness of the proposed snubber in wind turbine systems.