Highly Efficient 12kVA Inverter with Natural Convection Cooling Using SiC Switches

摘要

This paper presents a 12kVA three phase inverter with 1200V SiC-JFETs with an efficiencyrnof up to 99.5%. The inverter is cooled by natural convection with an overall heat sink volume of twornlitres only. SiC switches cause lower conduction and switching losses compared with Si-IGBTs of thernsame voltage and current rating, which increases the inverter efficiency and reduces the volume andrnweight of the cooling system. Especially for natural convection cooling, the cooling system can bernsized down extremely. Due to the fast switching transients of the JFETs, the dead time of the inverterrnbridges can be shortened to 200ns. On the other hand, the fast switching transients set high requirementsrnon the design of the driver and of the commutation circuit. The normally-on behaviour of thernSiC-JFETs is circumvented by utilizing the “Direct Driven JFET” topology introduced in [1]. Instead ofrnSi n-channel MOSFETs used in [1], low voltage Si p-channel MOSFETs are integrated to the module,rnwhich allows a single driver supply voltage. The presented inverter was developed as a demonstratorrnwithin the project “Highly efficient converters with SiC semiconductors”, funded by ECPE.