Active Drive Voltage Balancing Control Based on Charge Transfer Method for Series‐Connected SiC MOSFETs Application

ABSTRACT The switching process of MOSFETs is essentially dominated by the charging and discharging of gate nonlinear parasitic capacitances, where the dynamic charge variations of these capacitances play a decisive role in the device's switching transient characteristics. For series‐connected SiC MOSFETs, deviations in turn‐off charge transfer, which are caused by semiconductor parameters, gate drive circuit parameters, and gate signal mismatch, ultimately lead to voltage imbalance among the series devices. To address this issue, this paper proposes an active gate drive charge compensation control strategy focusing on the voltage rise phase of series‐connected MOSFETs. Based on a charge‐dependent SiC MOSFET model, the voltage variation of the device is interpreted as a charge transfer process, and a quantitative relationship between the discharge charge and the turn‐off voltage is established. An auxiliary current source is introduced to regulate the charge transfer process, compensating for the unbalanced discharge charges generated during turn‐off. This strategy not only accelerates the turn‐off process of SiC MOSFETs but also achieves effective voltage balance among series‐connected devices by mitigating the impact of gate discharge deviations. An experimental platform is established to verify the feasibility of the proposed strategy.