A 100kHz 95.91% efficiency SiC-device-based split output converter with EMI reduction

Abstract

The adoption of silicon carbide (SiC) MOSFETs and SiC Schottky diodes in power converters promises a further improvement of the attainable power density and system efficiency, while it is restricted by several issues caused by the ultra-fast switching, such as phase-leg shoot-through (‘crosstalk’ effect), high turn-on losses, electromagnetic interference (EMI), etc. This paper presents a split output converter which can overcome the limitations of the standard two-level voltage source converters when employing the fast-switching SiC devices. The split output converter uses auxiliary inductors (called ‘spilt inductors’) to decouple the upper SiC MOSFET and the lower SiC MOSFET of the same phase leg, thus suppressing the crosstalk effect, improving the switching performance (e.g. lower turn-on losses), and reducing the EMI. However, there are also several issues brought by the split inductors, e.g. the current freewheeling problem, the current pulses and voltage spikes of the split inductors, and the disappeared synchronous rectification, which can together increase the losses of the converter. A 95.91% efficiency has been achieved by the split output converter at the switching frequency of 100kHz with EMI reduction.