Comparison of switching devices for a zero-current switched class E based automotive inductive charging converter system

The zero-current switched Class E converter topologies offer great potential regarding energy efficiency and cost effectiveness for automotive inductive charging applications. In comparison to the Class D converter topologies the resonant current is not flowing in the semiconductor switching devices, reducing the system's sensitivity to variations of the charging-coil coupling. In this paper the performance of SiC MOSFETS are investigated and compared to the performance of a selected Si IGBT. A simplified test set-up with similar behavior as the inductive charging circuit has been developed that allows an accurate adjustment of the operating conditions of the switching devices. The waveforms obtained from the measurements confirm the theoretical predictions very well. It is shown that low switching losses are achieved mainly related to the discharge of the output capacitance of the SiC MOSFET. The results also show the suitability of the proposed topology for the given application.