High-temperature sic packaging for HEV traction applications

A key issue with Hybrid Electric (HEV) and Plug-in Hybrid Electric Vehicles (PHEV) is the cost of these products relative to traditional vehicles. Currently in most cases, the fuel savings do not offset the initial capital expenditure associated with a hybrid. Therefore, an important goal is the cost reduction of these products in order to allow consumers to justify the purchase of these vehicles rather than traditional alternatives. One possibility that could contribute to this goal is the elimination of the additional coolant loop and associated hardware that is currently required to cool the power electronics in these systems. In many of these systems, the internal combustion engine (ICE) requires a coolant loop with a maximum outlet temperature of 105°C and an additional loop is required at a lower temperature (typically 65°C) for the power electronics. This lower temperature loop is required due to the inability of silicon devices and traditional packaging technology to operate reliably at high temperatures. The ability to operate silicon carbide (SiC) devices at much higher temperatures would enable the elimination of the second cooling loop and decrease the cost of these vehicles. In addition, for some applications a suitable packaging technology and SiC devices may enable air-cooling rather than liquid cooling and potentially even further reduced cost. To that end, the researchers have developed a SiC packaging technology suitable for use in these applications. This technology allows the power devices to operate at 200+°C junction temperatures and significantly reduces the cooling requirements that exist in traditional HEV applications. By allowing this higher junction temperature, the power electronics can utilize the same coolant loop as the ICE in a reduced size. This paper will report on this packaging technology and its use with SiC devices.