Comparison of SiC MOSFET-based and GaN HEMT-based high-efficiency high-power-density 7.2 kW EV battery chargers

摘要

As two exemplary candidates of wide-bandgap devices, SiC MOSFETnns and GaN HEMTnns are regarded as successors of Si devices in medium-to-high-voltage (>1200 V) and low-voltage (<650 V) domains, respectively, thanks to their excellent switching performance and thermal capability. With the introduction of 650 V SiC MOSFETs and GaN HEMTs, the two technologies are in direct competition in <650 V domains, such as Level 2 battery chargers for electric vehicles (EVs). This study applies 650 V SiC and GaN to two 240 VAC/7.2 kW EV battery chargers, respectively, aiming to provide a head-to-head comparison of these two devices in terms of overall efficiency, power density, thermal performance, and cost. The charger essentially is an indirect matrix converter with a dual-active-bridge stage handling the power factor correction and power delivery simultaneously. These two chargers utilise the same control strategy, varying the phase-shift and switching frequency to cover the wide input range (80–260 VAC) and wide output range (200 V–450 VDC). Experimental results indicated that at the same efficiency level, the GaN charger is smaller, more efficient and cheaper, while the SiC charger has a better thermal performance.