Silicon carbide (SiC) and gallium nitride (GaN) power devices, with their excellent characteristics such as high switching speed and low on-resistance, are driving the development of power electronic converters toward higher frequency and efficiency. However, the high-speed application of SiC and GaN power devices faces issues including turn-off overvoltage, turn-on oscillation, and bridge circuit crosstalk, which limit further improvement in their switching speed. This paper focuses on the aforementioned problems in the high-speed application of SiC and GaN power devices and conducts the following research.

First, based on a standardized test circuit, the influence of circuit parameters on the switching characteristics of SiC and GaN power devices is analyzed. A double-pulse simulation platform is built using LTspice software to evaluate the impact of gate resistance, power loop inductance, common source inductance, and gate-drain parasitic capacitance on the switching characteristics of power devices. To obtain accurate test results, this paper standardizes the selection of test equipment and test points based on theoretical analysis and experimental verification, providing theoretical guidance for the standardized testing of switching characteristics of SiC and GaN power devices.

Next, the mechanism of turn-off overvoltage is analyzed in detail based on the turn-off process of SiC and GaN power devices. The influence of the capacitance value, placement position, and parasitic inductance of high-frequency decoupling capacitors on turn-off overvoltage is analyzed using terminal impedance analysis, providing a theoretical basis for the selection of high-frequency decoupling capacitors and circuit decoupling design. Furthermore, the impact of common source inductance on turn-on oscillation in non-Kelvin packaged devices is analyzed in detail based on the turn-on process. An SRD (Resistor and Diode in Series) type drive circuit is proposed to suppress turn-on oscillation in non-Kelvin packaged devices, thereby further improving the turn-on speed of switching devices and reducing turn-on losses.

Finally, the crosstalk mechanism in bridge circuits is analyzed based on different packaged devices, and a double-pulse experimental platform is built to evaluate the effects of common source inductance of the passive device, gate resistance of the passive device, gate resistance of the active device, and gate-drain junction capacitance of the passive device on bridge circuit crosstalk. To prevent the mis-triggering of the passive device caused by bridge circuit crosstalk, an RCD (Resistance-Capacitance-Diode) type bootstrap negative voltage drive circuit suitable for bridge circuits is proposed. This drive circuit requires only one auxiliary power supply to achieve negative voltage turn-off for the gate-source of the upper and lower switches in the bridge circuit, and the negative turn-off voltage is flexibly adjustable and unaffected by the duty cycle.

Keywords: Silicon carbide; Gallium nitride; Parasitic parameters; Turn-off overvoltage; Turn-on oscillation; Bridge crosstalk; Drive circuit