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).

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 a push-pull converter as a promising alternative to more complex and more costly isolated dc-dc converters for cost-sensitive, high-performance applications. The push-pull converter utilizes silicon carbide (SiC) power devices along with an active energy recovery clamp (AERC) circuit to extend the conventional operational limits of the topology. The SiC devices provide higher voltage blocking capability while maintaining low on-resistance as well as low switching energy. The AERC allows for nearly all of the energy stored in the leakage inductance of the transformer to be transferred back to the input capacitors without adding any control complexity to the system. The use of SiC devices along with the AERC allows for the push-pull converter to operate at a higher voltage, higher current, and higher switching frequency while maintaining high efficiency. In this work a prototype is developed to be operated with an input voltage of 400 V, a switching frequency of 200 kHz, and an output power greater than 5 kW. The performance of this prototype is compared to the same push-pull converter using an RCD clamp and significant improvements in efficiency are seen. The push-pull converter with AERC also shows higher efficiency across a wide range of output power conditions when compared to a soft-switching phase-shifted full-bridge (PSFB) converter with similar design specifications. Overall a maximum efficiency of 96.5% was measured at an output power of 3.7 kW for the push-pull converter with AERC.

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