access icon openaccess A 99%-efficiency GaN converter for 6.78 MHz magnetic resonant wireless power transfer system

The authors developed a high-efficiency gallium-nitride (GaN) Class-E converter for a 6.78 MHz magnetic resonant wireless power transfer system. A negative-bias gate driver circuit made it possible to use a depletion mode GaN high-electron-mobility transistor (HEMT), and simplified the converter circuit. As the depletion mode GaN HEMT with very small gate–source capacitance provided almost ideal zero-voltage switching, the authors attained a drain efficiency of 98.8% and a total efficiency of 97.7%, including power consumption of a gate driver circuit, at a power output of 33 W. In addition, the authors demonstrated a 6.78 MHz magnetic resonant wireless power transfer system that consisted of the GaN Class-E converter, a pair of magnetic resonant coils 150 mm in diameter with an air-gap distance of 40 mm, and a full-bridge rectifier using Si Schottky barrier diodes. The system achieved a dc–dc efficiency of 82.8% at a power output of 25 W. The efficiencies of coil coupling and the rectifier were estimated to be ∼ 94 and 90%, respectively.

Inspec keywords: power convertors; III-V semiconductors; driver circuits; Schottky diodes; high electron mobility transistors; inductive power transmission; rectifiers; gallium compounds

Other keywords: size 150 mm; gate–source capacitance; efficiency 82.8 percent; size 40 mm; drain efficiency; power 33 W; efficiency 97.7 percent; magnetic resonant coils; power 25 W; negative-bias gate driver circuit; Si; frequency 6.78 MHz; magnetic resonant wireless power transfer system; depletion mode GaN high-electron-mobility transistor; efficiency 98.8 percent; gallium-nitride Class-E converter; GaN; depletion mode GaN HEMT; GaN Class-E converter; Si Schottky barrier diodes; full-bridge rectifier

Subjects: Power convertors and power supplies to apparatus; Other power transmission; Junction and barrier diodes; Power electronics, supply and supervisory circuits; Other field effect devices

References

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