A Magnetic Coupling Based Gate Driver for Crosstalk Suppression of SiC MOSFETs

Silicon carbide (SiC) devices have attracted widespread attention because of their superior characteristics. However, not only the higher slew rate of drain-source voltage but also the higher slew rate of reverse recovery current can result in a more serious crosstalk problem than Si-based devices in a half-bridge application. Crosstalk suppression should be integrated into the gate driver to ensure the safe operation of SiC devices. Therefore, a specific mathematical analysis is done in this paper to figure out the crosstalk phenomenon. The limitations of the existing suppression methods are illustrated. Thus, a gate driver based on the magnetic coupling is proposed to ensure the gate-source voltage within the safe range, even when the positive and negative spurious pulse voltages appear. The proposed gate driver uses three ring transformers to insulate the control signal and driver power supply. So, it is feasible to drive a half-bridge circuit in the medium or high power applications. By saving optical couplers and isolated drive power supplies, the gate driver can realize fully galvanic isolation and generate the positive and negative gate-source driving voltage simply. The results derived from the proposed mathematical analysis and the effectiveness of the proposed driver in suppressing the spurious pulse voltage are verified by the experiments.