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Wireless Power Transmitter and Receiver Supporting 200-kHz and 6.78-MHz Dual-Band Operation without Magnetic Field Canceling
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- Authors
- Dukju Ahn, Seongmin Kim, Sang-Won Kim, Jungick Moon, Inkui Cho
- Issue Date
- 2017-09
- Citation
- IEEE Transactions on Power Electronics, v.32, no.9, pp.7068-7082
- ISSN
- 0885-8993
- Publisher
- IEEE
- Language
- English
- Type
- Journal Article
- Abstract
- The paper proposes a method to suppress the anticurrent and magnetic canceling in a dual-band transmitter (Tx) and receiver (Rx) for wireless power transfer. The problem of intracoupling between the two coils in a dual-band resonator is analyzed. During 6.78-MHz operation, the intracoupling causes antidirectional current at 200-kHz coil which cancels the magnetic field and degrades efficiency. To solve the problem of antidirectional current, a new resonator design method is proposed. The proposed technique suppresses the 6.78-MHz anticurrent by specially selecting the impedance values and coil-winding direction that manipulate the magnitude and phase of 6.78-MHz voltage, such that total voltage across 200-kHz path is zero. One of the advantages is that the spatial separation between 6.78-MHz coil and 200-kHz coil can be reduced, which allows the maximum diameter for inner coil. Also, smaller discrete inductor can be used. The two coils share an inverter (or a rectifier), thus minimizing the number of inverter and rectifier. The 24-W system with dual-band Tx achieves 70.3% and 70.8% efficiencies at 6.78 MHz and 200 kHz, respectively, whereas the system with dual-band Rx achieves 66.3% and 74.3% at 6.78 MHz and 200 kHz, respectively. The efficiency improvement due to anticurrent suppressing is 4.8~23.6%.
- KSP Keywords
- Design method, Dual-band operation, Dual-band resonator, Dual-band transmitter, Magnetic field, Magnitude and phase, Maximum diameter, Resonator design, Total voltage, Transmitter and receiver, Wireless power transfer