Conducted Common-Mode Electromagnetic Interference Analysis of Gate Drivers for High-Voltage SiC Devices

Power conversion equipment based on high-voltage SiC devices offers significant advantages in efficiency and power density. However, during high-voltage, high-power switching operations, severe electromagnetic interference (EMI) can easily occur. It could cause the false triggering of devices and result in converter failure in severe conditions. This paper firstly establishes a mathematical model and conducts simulation analysis of the conducted common-mode interference path in high-voltage SiC device gate driver circuits. Based on the driver circuit architecture, a modeling method for the common-mode interference conduction network in half-bridge submodules is proposed, clarifying the key factors contributing to high common-mode currents. A low common-mode current design methodology for high-voltage SiC submodules is presented, including driver loop structure optimization, capacitor design, and submodule integration. A highly integrated 3.3 kV SiC-based submodule prototype has been successfully developed, serving as a building block for constructing multilevel modular converters (MMCs). Simulation and experimental results indicate that the amplitude of the common-mode current is primarily influenced by the coupling capacitance of the auxiliary power supply, exhibiting a proportional relationship. The developed SiC submodule achieves high-speed switching at 50 kV/μs under a 2 kV DC bus voltage, with excellent thermal stability and low common-mode current characteristics, validating the effectiveness of the proposed model and design approach.