Evaluation of SiC JFETs and SiC Schottky diodes for wind generation systems

Recent achievements related to the use of silicon carbide (SiC) devices in wind generation systems (WGSs) are presented in the paper. With applications in WGS, the choice of high-temperature, high-frequency SiC devices reduces the volume and size of power electronic converters, particularly their passive filters which dominate the weigh of the converter. The SiC-based power converters are expected to have three times lower losses than silicon-based AC-DC-AC converters currently applied to the wind turbines. Efficiency improvement can be particularly significant at low wind speeds where the WGS operates most of the time. The paper presents results obtained for the 30A 1200V generator side SiC JFET-based DC-AC converter with a switching frequency 100 kHz. The prototype was worked out and investigated at the Gdansk University of Technology. A special attention is paid to the performance of two stage DC-coupled gate driver circuit. Static and dynamic characteristics of 1200V SiC devices (JFETs and Schottky diodes) used in the WGS DC-AC converter are investigated. An approach to suppression of undesirable oscillations/EMI problems caused by the high dv/dt of SiC devices is presented.