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Conference Paper
Design of Wireless Power Charging using Coupled Magnetic Resonance to 12V, 20Ah LiFePO4 Battery
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- Authors
- Seong-Min Kim, Jung-Ick Moon, In-Kui Cho, Jae-Hun Yun, Woo-Jin Byun
- Issue Date
- 2014-08
- Citation
- Progress in Electromagnetics Research Symposium (PIERS) 2014 in Guangzhou, pp.1-2
- Publisher
- IEEE
- Language
- English
- Type
- Conference Paper
- Abstract
- In this paper, a wireless charging system using the coupled magnetic resonance method is presented. The wireless charging system is applied to a walking assistance vehicle with a 12V, 20Ah LiFePO4 battery. The charging system is composed of a 130W power transmitter, a 100W full-bridge receiver and a constant current battery charging circuit. The power is implemented using DDS(Direct Digital Synthesizer) and a Class-F power amplifier. The operating frequency range of the power transmitter is from 1.6MHz to 2.0MHz. The transmit resonator is designed as a two layer spiral structure and its resonance frequency is 1.78MHz. The diameter of the transmit resonator is 40cm. The receive resonator is designed as same structure and same resonance frequency with 20cm diameter. The 100W power receiver is implemented using a full-bridge diode rectifier, active dummy load circuit and OVP(Over Voltage Protection) circuit. The active dummy load circuit is designed to maintain the receiver input impedance even when the road changes. The constant current charging circuit is designed for battery charging and communication to the power transmitter. The communication between the power transmitter and the charging circuit is implemented for the purpose of transmit power control. The power control algorithm is designed to maintain the system power efficiency. The communication scheme is 400MHz band 9.6kbps FSK. By the measurement results, the average charging power is 45W and the average transmit power is 80W. The DC/DC system efficiency is about 51%
- KSP Keywords
- Charging power, Class-F, Constant current(CC), Coupled magnetic resonances, Diode rectifier, Full-bridge, Input Impedance, LiFePO4 battery, MHz band, Magnetic resonance(MR), Over Voltage