Voltage Balancing Scheme Based on Active Voltage Cross Control for Series-Connected IGBTs

In order to increase the rating voltage in high voltage power converters, series connection of IGBTs is an alternative method. The key challenge is to reduce the collector-emitter voltage mismatch during the steady state and switching transients. Due to the fact that the master-slave control strategy lacks control ability of the master device, an active voltage cross control method is proposed in this paper for balancing the dynamic voltages among series-connected IGBTs thus providing good condition for steady-state voltage balance. The proposed circuit overcomes the restriction where only one IGBT can be configured as the master device and reduces the complexity of control. This method is theoretically analyzed with series connection of two IGBTs and simulated in Orcad PSpice software with 100 nanoseconds gate signal delay mismatch. The simulation results show good consistency with the theoretical analysis and verify the proposed idea.