Evaluation of Power Losses and Ruggedness of SiC MOSFETs for use in High-Power High-Frequency Induction Heating Generators
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- Institutt for elkraftteknikk 
As the Si IGBTs are confronting its physical limitations when it comes to high-frequency high-power applications, the SiC MOSFET sails up as a promising substitute due to its material properties. However, in the process of developing next generation induction heating generators based on SiC technology, power loss and reliability considerations should be evaluated thoroughly. Soft-switching is mandatory to keep losses low in high-frequency high-power applications. In this thesis the power losses and reliability of a 1.2 kV FCA120A50 DioMOS half-bridge device from SanRex Panasonic for use in induction heating generators are evaluated. The power losses are measured with both an electrical and calorimetric approach. Where the electrical loss measurements results in an overestimation of 28.28 % to 34.50 % of total power losses, in relation to the measured calorimetric losses. Further, measurements of the on-state resistance as function of current and as function of temperature are carried out, where a moderate increase in on-state resistance are observed in both cases. Furthermore, by increasing the gate-source voltage the on-state resistance are reduced, and hence the conduction losses. By increasing the gate-source voltage from 19.1 V to 21.23 V at 128 kW 247 kHz the total losses are reduced by 8.95%, obtaining an inverter efficiency of 99.4 %. As a consequence of increased gate-source voltage, the risk of very high short-circuit currents is severe. An increase from 648 A to 1134 A of the short-circuit current are measured when increasing the gate source-voltage from 19 V to 21 V. However, the device limits the short-circuit current and turns off safely after 1.34 us. Moreover, when operated out of soft-switching conditions a moderate increase of 12.12% in total losses is observed. Thus, the 1.2 kV FCA120A50 DioMOS half-bridge device from SanRex Panasonic proves to be extremely efficient and robust for industrial induction heating applications.