An Adaptive Driving Signals Delay Control for Voltage Balancing of Series-Connected SiC MOSFETs

Voltage unbalance during the switching transient is a challenge of series-connected silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET). Adjusting the delay time of the device's drive signals is an effective method for voltage balancing. However, the relationship between the delay time and the drain-source differential voltage is greatly affected by the load current, so it is difficult for proportional-integral (PI) controller to meet the requirements of practical work situations where the load current changes inevitably. In order to solve this problem, this paper proposes an adaptive control method. This method can adjust the controller's parameters in real time according to the load current, so as to achieve a reliable voltage balancing. Experimental results are presented to verify the practicability and flexibility of this method, meanwhile, the robustness of the system improved by applying this strategy.