A Gate Drive Circuit and Dynamic Voltage Balancing Control Method Suitable for Series-Connected SiC mosfets

Compared with silicon insulated-gate bipolar transistor, silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (mosfet) presents good features that it clearly shows on its switching and thermal performance. However, the fast switching speed of SiC mosfet makes it much more difficult for solving the dynamic voltage imbalance problem caused by the parameter fluctuations of the SiC mosfets and drive circuits when they are connected in series. This article proposes an effective gate drive circuit and its dynamic voltage balancing control method to tackle this issue. The proposed method not only balances the dynamic voltage during high-speed switching but also adapts to the variation of the dc-bus voltage by utilization of overdrive control method (ODCM). Furthermore, to widen the control range of the ODCM, a switched-capacitor compensation method by switching and combining different drive capacitors into different values is proposed. The operation principles and the parameter design method are discussed in detail. The performance of the proposed series-connected SiC mosfets gate drive circuit and its dynamic voltage balancing control method is validated by experimental results. The dynamic voltage can be well balanced within the design range.