Packaging of High Frequency, High Temperature Silicon Carbide (SiC) Multichip Power Module (MCPM) Bi-directional Battery Chargers for Next Generation Hybrid Electric Vehicles

Abstract

The packaging design and development of an on-board bi-directional charger for the battery system of the next generation Toyota Prius plug-in hybrid electric vehicle (PHEV) will be presented in this paper. The charger implements a multichip power module (MCPM) packaging strategy. The Silicon Carbide (SiC) MCPM charger is capable of operating to temperatures in excess of 200°C and at switching frequencies in excess of 500 kHz, significantly reducing the overall size and weight of the system in comparison with Toyota's present silicon-based Prius charger. The present actively cooled Si charger is capable of delivering a peak power of 1kW at less than 90 percent efficiency, is limited to less than 50 kHz switching, and measures greater than 6.3 liters with a mass of 6.6 kg, resulting in a power density of 150 W/kg. The passively cooled SiC MCPM charger presented herein was designed to deliver a peak power of 5 kW at greater than 96% efficiency, while measuring less than 0.9 liters with a mass of 1 kg, resulting in a power density greater than 5 kW/kg. Thus, the novel SiC MCPM charger represents an increase in power density of more than 30×, a very significant power density achievement in size and weight for sensitive mobile applications such as PHEVs. This paper will discuss the overall mechanical design of the SiC MCPM charger, the finite-element modeling and analysis of thermal and stress considerations, characterization and parasitic analysis of the MCPM, and the development of high temperature solutions for SiC devices.