Performance Improvement of a Silicon Partial Power Converter over a Silicon Carbide Full Power Converter

Abstract

This article studies the new benefits that partial power processing brings to Silicon (Si) devices compared to wide-bandgap technologies. To prove this, the proposed case study consists of an on-board charger (OBC) application in which a Si-based partial power converter (PPC) is compared with a Silicon Carbide (SiC) based full power converter (FPC). The OBC application considers three different technologies of lithium-ion batteries and the main comparison metrics are: semiconductor switching, temperature rise of semiconductors, volume and device losses (efficiency). This last one is oriented to energy losses (Wh) and not to power losses (W) as classical design. An analytical model is used to compute switching and conduction losses. Depending on the operating point, switching events are segregated into zero voltage switching (ZVS), incomplete ZVS and hard switching. It is shown that the Si-based PPC may enter non-ZVS in certain operating conditions. However, its efficiency remains above 99 %, producing up to 5 times lower energy losses than the SiC-based FPC. Also, the case temperature of the semiconductors is halved and a reduction in the volume and electrical stress of the devices is achieved. This permits a global multi-objective optimization. The results are experimentally validated using a 3 kW prototype of SiC-based FPC and Si-based PPC.