Design and analysis of a voltage clamping active delay control method for series connected SiC MOSFETs

Series connection of power devices is an attractive approach to overcome the obstacle of the blocking voltage limitation of a single power device. However, voltage balancing measures should be taken to assure the anticipated performance of series connected power devices. In this paper, based on emerging silicon carbide (SiC) metal-oxide semiconductor field-effect transistors (MOSFETs), a clamping resistor-capacitor-diode circuit-based voltage clamping active delay control method is proposed to improve their voltage balancing performance. Compared with existing active delay control methods which sample the drain-source voltages of SiC MOSFETs as feedbacks, this proposed method utilizes the voltages of clamping capacitors as control criteria, which exhibits two prominent advantages: (1) an accurate model of the system is easier to attain (2) the feedback loop is simpler to design. After detailed demonstration of this method, the corresponding model is established to help determine appropriate control parameters, and experiments finally validate the effectiveness of the proposed method.