Performance Comparison of the Auxiliary Resonant Commutated Pole Inverter (ARCPI) using SiC MOSFETs or Si IGBTs

SiC MOSFETs have the potential to replace Si IGBTs bringing in significant performance improvement to existing power converters. However, there is a lack of systematic and conclusive investigation into SiC MOSFET soft-switching inverters regarding the switching performance, electromagnetic interference (EMI), and efficiency. This paper compares the performance of a three-phase, 6 kW soft-switching inverter, i.e. the auxiliary resonant commutated pole inverter (ARCPI), which is constructed with SiC MOSFETs and then with Si IGBTs to highlight the opportunities and challenges of using SiC MOSFETs. Experimental results show that the ARCPI using SiC MOSFETs has better performance than that using Si IGBTs due to its faster switching speed, under the same circuit parameters and control method. Firstly, the ARCPI using SiC MOSFETs can realise full zero voltage switching and the switching transient behaviour is more predictable. Unlike Si IGBTs, SiC MOSFETs have no turn-off tail current. Thus, there is no switching loss in the SiC MOSFET. Secondly, the ARCPI using SiC MOSFETs endures less current stress when compared to the Si IGBTs counterpart. Thirdly, the ARCPI using SiC MOSFETs exhibits better EMI performance and higher efficiency. Specifically, a maximum 20 dBμV harmonic content can be attenuated around 800 kHz region and a 3.9% efficiency can be improved at the power of 6 kW when compared to the Si IGBTs counterpart. The poor performance of the ARCPI using Si IGBTs is because the turn-off delay of Si IGBTs introduces more energy into the resonant circuit than designed, resulting in steeper output voltage edge, higher current stress and more conduction loss.