High-Efficiency Silicon Carbide (SiC) Converter Using Paralleled Discrete Devices in Energy Storage Systems

Energy storage (ES) systems are key enablers for high penetration of renewables. Silicon carbide (SiC) devices can benefit ES converters as well as the whole ES system. This paper focuses on the development of a high-efficiency SiC-based ES converter. First, topologies for ES converter considering system requirement and device rating/availability are discussed with pros and cons of each candidate summarized. Two-level voltage source converter with paralleled discrete SiC devices in mature packages (e.g. TO-247) is selected due to lower converter complexity, increased device availability and shorter lead time. Then, gate drive and layout design for current sharing between paralleled devices are presented. The impact of device parameter mismatch (e.g. threshold voltage) on switching loss is also evaluated. Moreover, design consideration on thermal management for paralleled devices is discussed. Finally, a 60 kW ES converter with four GE 1700 V SiC MOSFETs is prototyped and experimentally demonstrated with around 99% efficiency in wide operating conditions.