This paper presents an isolated on-board vehicular battery charger that utilizes silicon carbide (SiC) power devices to achieve high density and high efficiency for application in electric vehicles (EVs) and plug-in hybrid EVs (PHEVs). The proposed level 2 charger has a two-stage architecture where the first stage is a bridgeless boost ac-dc converter and the second stage is a phaseshifted full-bridge isolated dc-dc converter. The operation of both topologies is presented and the specific advantages gained through the use of SiC power devices are discussed. The design of power stage components, the packaging of the multichip power module, and the system-level packaging is presented with a primary focus on system density and a secondary focus on system efficiency. In this work, a hardware prototype is developed and a peak system efficiency of 95% is measured while operating both power stages with a switching frequency of 200 kHz. A maximum output power of 6.1 kW results in a volumetric power density of 5.0 kW/L and a gravimetric power density of 3.8 kW/kg when considering the volume and mass of the system including a case.Index Terms-AC-DC power converters, battery charger, dc-dc power converters, electric vehicles (EVs), power electronics, silicon carbide (SiC).

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A gate buffer fabricated in a 2-μm 4H silicon carbide (SiC) process is presented. The circuit is composed of an input buffer stage with a push-pull output stage, and is fabricated using enhancement mode N-channel FETs in a process optimized for SiC power switching devices. Simulation and measurement results of the fabricated gate buffer are presented and compared for operation at various voltage supply levels, with a capacitive load of 2 nF. Details of the design including layout specifics, simulation results, and directions for future improvement of this buffer are presented. In addition, plans for its incorporation into an isolated high-side/low-side gate-driver architecture, fully integrated with power switching devices in a SiC process, are briefly discussed. This letter represents the first reported MOSFET-based gate buffer fabricated in 4H SiC.Index Terms-Gate buffer, gate driver, high-temperature electronics, silicon carbide (SiC), 4H-SiC.

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This paper presents the testing results of an allsilicon carbide (SiC) intelligent power module (IPM) for use in future high-density power electronics applications. The IPM has high-temperature capability and contains both SiC power devices and SiC gate driver integrated circuits (ICs). The hightemperature capability of the SiC gate driver ICs allows for them to be packaged into the power module and be located physically close to the power devices. This provides a distinct advantage by reducing the gate driver loop inductance, which promotes highfrequency operation, while also reducing the overall volume of the system through higher levels of integration. The power module was tested in a bridgeless-boost converter to showcase the performance of the module in a system level application. The converter was initially operated with a switching frequency of 200 kHz with a peak output power of approximately 5 kW. The efficiency of the converter was then evaluated experimentally and optimized by increasing the overdrive voltage on the SiC gate driver ICs. Overall a peak efficiency of 97.7% was measured at 3.0 kW output. The converter's switching frequency was then increased to 500 kHz to prove the high-frequency capability of the power module. With no further optimization of components, the converter was able to operate under these conditions and showed a peak efficiency of 95.0% at an output power of 2.1 kW.

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.