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Characterization and Loss Estimation of Bridge-based Converter with SiC JFET

Fig. 1. JFET conduction resistance in two directions.
SiC devices have obvious advantages comparing with conventional Si devices especially in high temperature range. This paper aims at developing a method of calculating the loss of SiC JFET bridge-based converter. Steady state performance of SiC JFET and Schottky diode in different temperature is studied and an improved conduction loss evaluation is proposed considering conduction loss differences in two directions. SiC JFET bridge testbed in introduced and the switching losses in different temperature are calculated both for with and without freewheeling diode. Experimental results show that with SiC Schottky diode as freewheeling diode the reverse recovery effect in switching is improved and switching loss is less. Then based on the experimental results, losses of two typical three-phase AC-DC-AC converters are calculated. Experimental results show that with freewheeling Schottky diode, both conduction loss and switching loss can be decreased especially in high temperature.

Fig. 2. SiC Schottky diode (C2D10120) conduction characteristics.
Fig. 3.
Fig. 4. SiC JFET bridge test circuit.

Fig. 5. JFET turning on only with JFET.
Fig. 6. JEFT turning on with both JFET and diode.
Fig. 7. Case 1 of AC-DC-AC converter: without freewheeling diode.

Fig. 8. Case 2 of AC-DC-AC converter: with freewheeling diode
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