Monty B. Hayes

The effects of solder voids in the device to substrate interface for electric vehicle and other power applications

The hybrid power module is a main component of the GM EV1 electric vehicle inverter system. It is a high power, high frequency, switching device that converts traction battery DC power to controlled AC power to drive the electric motor. The key to the HPMs ability to generate and switch large amounts of power lies in the modules ability to successfully maintain a constant T/sub j/ across the IGBT and transfer heat through a reliable thermal stack. It is known that defects, such as solder voids, in the thermal stack will reduce the localized thermal conductivity of the effected area. This will lead to excessive T/sub j/ on the chip, and corresponding high delta temperatures between chip and case. High temperature conditions such as this will therefore limit device performance or lead to premature device failure. This paper investigates the integrity of these solder joints for electric vehicles and other high power applications.

650 V, 7 mΩ 4H-SiC DMOSFETs for Dual-Side Sintered Power Modules

In this paper, we present our latest results on 650 V 4H-SiC DMOSFET developments for dual-side sintered power modules in electric drive vehicles. A low specific on-resistance (Rsp,on) of 1.8 mΩ⋅cm2 has been achieved on 650 V, 7 mΩ 4H-SiC DMOSFETs at 25°C, which increases to 2.4 mΩ⋅cm2 at 150°C. For the first time, the DMOSFET chip is designed specifically for use in dual-side soldering and sintering processes, and a 650 V, 1.7 mΩ SiC DMOSFET multichip half bridge power module has been built using the wirebond-free assembly. Compared to a similarly rated Si IGBT module, the conduction and switching losses were reduced by 80% and ~50%, respectively.

Development of a power dense and environmentally robust traction power inverter for the second-generatio chevrolet VOLT extended-range EV

By significantly re-engineering to reduce physical size and mass of the traction power inverter module (TPIM) for 2nd generation Chevrolet VOLT Extended-Range EV it is possible to mount the inverter to the transmission and meet all performance targets, maintain high reliability and environmental robustness. The Chevrolet VOLT is an electric vehicle with extended-range. It is capable of operation on battery power alone, and on hybrid/ engine power after depletion of the battery. 1st generation Chevrolet VOLTs (VOLT-1) were driven over half a billion miles in North America from October 2013 through September 2014, 74% of which were all-electric [1, 12]. For 2016, GM has developed the 2nd generation of the VOLT (VOLT-2) vehicle and “Voltec” propulsion system. This effort by GM and Delphi provides a significant cost benefit to the overall system by eliminating costly AC traction cables. Effort was taken to the electrical design of the power switch to achieve efficiency target and thermal challenges. A novel cooling approach enables high power density while maintaining a very high overall conversion efficiency. Design focus was applied to the mechanical design of this TPIM to provide extremely stiff frame required for reliability in the transmission environment and reduce integration cost.