Loss Reduction by Synchronous Rectification in a 50 kW SiC-based Inductive Power Transfer System

Paper in proceedings, 2020

With development in wide band-gap semiconductors, such as silicon carbide (SiC), inductive power transfer (IPT) has become a promising technology for charging electric vehicles (EV). To meet fast charging demands by consumers, higher power levels in IPT is required. The power in IPT is usually limited by thermal stress due to losses at the vehicle side. Synchronous rectification is an efficient way to reduce losses compared to passive rectification. In this paper, the loss reduction accounted to synchronous rectification is quantitatively evaluated. The level of reductions varies depending on the load level, primary voltage, and constant current or constant voltage (CCCV) operation. The analytical results support the simulation results for various operating points. The loss profiles are studied for different dc-link voltages and duty cycles. An 800 V, 50 kW dual-active bridge test setup with series-series compensation is constructed and experiments are done for verification. The setup is arranged in a back-to-back configuration with a common dc-link. Experimental result shows that losses are reduced by up to 60 % on the receiving side with synchronous rectification. At rated operation the losses are reduced by 100 W in the secondary side inverter.