Research on high voltage turn-off topology of IGCT gate unit

Abstract

As the important part of the high-power semiconductor IGCT, the gate unit which is named GU, controls the turn-on and turnoff actions of GCT. For the GU, the cathode current commutation relies on the energy stored in the turn-off capacitor stack to realize current transfer. At the same time, the forward voltage of the turn-off circuit can't be lower than the reverse voltage generated by the parasitic parameters. Therefore, the capacitance and voltage of the turn-off capacitors need to meet the maximum current of IGCT. The turn-off capacitor stack usually uses the aluminum electrolytic capacitor, which includes the disadvantages of large size, low life, and temperature limit. In order to reduce the volume and increase the life of the product, and also ensure the reliable of the turn-off process. This paper researches and explains the principle of the turn-off energy regenerative or dynamic adjustment topology, and analyzes the control strategy of the high-voltage turn-off topology, then the prototype test verifies that the topology obtains the same turn-off ability under the same current, but it can greatly reduces the capacity of the turnoff capacitors. And it can guarantee the dynamic and static characteristics of the turn-off process.