A novel turning-off circuit design for IGCT gate unit

The gate unit is the main part of the high-power semiconductor device IGCT, and it controls the turning-on and turning-off of GCT. For the gate unit, the cathode current commutation relies on the energy stored in the turning-off capacitor stack. In order to achieve the reliable turning-off and increase the turning-off capability, some methods can be done, such as: reducing the parasitic parameter of the turning-off circuit, selecting the electronic components with lower parasitic parameters, and increasing the gate cathode reverse voltage. But these methods are always limited, and the lifetime issue of electrolytic capacitors of turning-off circuit is a key factor which affects the life of IGCT. So based on the principle of IGCT, this paper proposes a novel turning-off circuit to ensure that the capacitance of the turning-off capacitor is extremely little under the same turning-off current, and it can fully guarantee the off state of IGCT. It is important to reduce the volume of the device, enhance the lifetime of the product, and extend application areas.