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RESEARCH PRODUCT

A Comparative Performance Study of a 1200 V Si and SiC MOSFET Intrinsic Diode on an Induction Heating Inverter

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This paper presents a comparison of the behavior of the intrinsic diode of silicon (Si) and silicon carbide (SiC) MOSFETs. The study was done for 1200 V Si and SiC MOSFETs. The data sheet from manufacturers shows the characteristics of MOSFET' intrinsic diode when gate source voltage (VGS) is 0 V. There are applications where the MOSFET' intrinsic diode is used while VGS is different than 0 V. One of these applications is induction heating, where depending on the load and the regulation system, the diode can conduct a significant part of the inverter current. In most applications which use the MOSFET' intrinsic diode, the turn ON of the intrinsic diode happens at VGS = 0 V. After a blanking time, the MOSFET' gate is activated waiting for the direction change of current in the circuit. Therefore, most of the current through the MOSFET' intrinsic diode occurs with a VGS different of 0 V. This paper shows the direct output characterization of Si and SiC MOSFET' intrinsic diode under different gate voltages. The gate resistor (RG) is an important parameter of the characterization. Depending on the input capacitance of the Si or SiC MOSFET, different RG are needed. The turn-on and turn-off behaviors are obtained when RG is optimized for each Si and SiC MOSFET. This has result in the turn-off robustness of intrinsic diode with optimum RG. This paper presents a surprising result for the reverse characteristic of Si and SiC MOSFETs for the same current at different VGS. The technology of Si MOSFET has different behavior depending on the manufacturer. The technology of SiC MOSFET presents a very similar behavior to low-voltage Si MOSFETs.