Mark Cairnie: Medium- and high-voltage Silicon Carbide power modules have the potential to drastically improve the size, reliability, and operating temperature of existing power systems due to faster switching times and reduced loss when compared to conventional silicon IGBTs. The proposed wirebond-less module seeks to reduce parasitics, enabling record switching speeds, while employing an innovative common-mode screen to reduce conducted noise emissions. The module housing and encapsulant is carefully designed to fully insulate the spring-loaded interconnects to the bus bar, eliminating the need for standard clearance requirements between the pins, and reducing the overall footprint of the module. Due to the close proximity of the interconnects, careful design of the gate driver and laminated bus bar is required to ensure low electric field strength and a safe partial discharge inception voltage. The gate driver and bus bar are fully integrated into a single six-layer PCB and utilize various field grating techniques to ensure a PDIV more than 150% of the DC bus voltage. The design is optimized for electric field strength, as well as parasitic loop inductance, using a finite element analysis method. From the design process, useful conclusions are drawn on the relationships and trade offs of various field grating techniques in high-density, high-voltage PCB design.

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