Development and testing of GaN Power Modules for EV traction inverters.

Abstract:
The necessity for affordable long-distance electrical cars is widely recognized. Gallium Nitride (GaN) is an acknowledged semiconductor technology for achieving this target through improved efficiency of the power train inverter. However, to successfully implement GaN in electric vehicle (EV) inverters, the challenges of high-power delivery must be resolved. High power, from a technical perspective, requires the design of high voltage, high current dice, driving in parallel of several dice, and maintaining low thermal resistance between the transistor junction and the coolant liquid of the inverter cold plate. Using power modules instead of discrete devices is an industry mainstream allowing for significantly higher power density. Developing and manufacturing modules with a new semiconductor material, such as GaN, and meeting the aggressive demand of carmakers to reduce cost, weight, and size of power modules while increasing delivered power calls for extraordinary inventiveness of engineers and well-orchestrated communication between packaging, electronics and semiconductor experts. To efficiently integrate power modules in EV inverters, and meet all the requirements stated above, A profound understanding of the trade-offs between different performance parameters and size is essential. This work will demonstrate how these challenges have been addressed in VisIC D3GaN power modules using the methodology of a demonstrator module based on discrete devices and the development of a transfer molded power module, based on bare dice. These modules were developed to showcase the D3GaN technology for EV traction inverters supporting up to 150kW and a battery voltage of 400V.