Half-bridge resonant inverter with SiC cascode applied to domestic induction heating

This paper presents an evaluation of a SiC MOSFET-JFET n-ON cascode structure for induction heating home appliances. In particular, the SiC cascode is applied in a resonant half-bridge inverter (HB-SCR). The cascode under test is comprised of a high power JFET n-ON in series with a low voltage MOSFET with a reduced conduction resistance. This small signal auxiliary device controls the conduction status of the main power JFET device. Operation modes for Zero Voltage Switching (ZVS) are analyzed. The obtained results are compared with those obtained with a similar resonant HB with n-ON SiC JFETs. The cascode structure applied to induction heating yields similar results in terms of conduction and switching than the classical resonant half-bridge. The improvement consists on a direct normally-off operation avoiding the need for additional security features and simplifying the driver circuit. Experimental verification of this stage applied to induction heating is presented in this paper opening future lines for driverless and snubberless inverters.