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inverter-slide4

The freewheeling diodes are of particular interest for this presentation. Wolfspeed's Silicon Carbide (SiC) diodes are highlighted for their role in optimizing the power efficiency of inverter circuits. The freewheeling or anti-parallel diodes, are used to route positive and negative inductive currents during switch transitions. Silicon diodes (usually PiN diodes), by nature of their materials and construction, contain minority carriers that recombine when the diode turns off, (blocking reverse voltage.) Recombination creates reverse recovery current that contributes to power loss in the system. These currents can be significant and get larger as the device gets hotter. SiC Schottkys, by nature of their materials and construction, are unipolar devices and thus contain no minority carriers. There is no recombination at turn-off, thereby eliminating recovery related losses in the system. There are many silicon devices available from major power semiconductor manufacturers designed to minimize recovery currents and even the few exotic silicon implementations that exist. However, only silicon carbide diodes eliminate the inherent generation of recovery currents.

PTM Published on: 2011-10-27