A hybrid voltage balancing method for series connected IGBTs

The series connection of IGBTs is required in high-voltage power converter to increase the rating voltage. The problem in series connection of IGBTs is to guarantee the voltage balance during the steady state and switching transients, in order to avoid damaging overvoltage. An improved master-slave control was proposed to provide simple and low voltage sensing circuit for multiple devices series connection. Due to the fact that active clamping and master-slave control strategy both lack control ability during some periods, a hybrid control method combined improved master-slave method with the active clamping method was proposed to ensure the balancing voltage in IGBTs over the whole period of IGBT commutation. The proposed hybrid voltage balance method is analyzed theoretically and simulated in PSPICE software, and a high voltage boost DC/DC converter with series connected IGBTs was built to test the proposed hybrid method. The experimental results fit the theoretical analysis and simulation well.