Performance Analysis of IGCT Clamp Circuit and Thermal Loss Modeling of IGCT Based

IGCTs have become the device of choice for high power applications, low losses and high reliability. They have been widely equipped in many Voltage Source Converters (VSC) for industry applications such as drives and railway interties etc. Converters employing IGCTs typically require a clamp circuit to eliminate hard turn-on of IGCT and control the diode recovery. A di/dt limiting circuit is required for the protection of freewheeling diodes from huge current derivatives and an over voltage limiting mechanism for the protection of IGCTs. This paper presents the performance evaluation of IGCT Clamp Circuit in terms of losses, as a function of load current in SEMIS (Semiconductor Simulation Tool). The proposed method based on dynamic measurement test data yields an accurate, yet computationally efficient method of loss calculation. Additionally, it also considers the temperature dependency of the reverse recovery current for the freewheeling diode losses. The results obtained from PLECS simulations for 6.5 kV, 150 mm RC-IGCT were compared against the results obtained from Synopsys TCAD, a semiconductor device simulation tool, for the same device with the same set of operating conditions. The results show a close match in terms of the clamp resistor energies during GCT and diode commutations.