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PROJECT TOPIC:  IMPROVING EFFICIENCY OF WIRELESS POWER TRANSFER VIA MAGNETIC RESONANCE
Department:  Electrical Electronics
AMOUNT:  20,000
FORMAT:   MS WORD
PAGES:  120
 
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OVERVIEW

IMPROVING EFFICIENCY OF  WIRELESSS POWER TRANSFER VIA MAGNETIC RESONANCE.

Wireless power transfer is essential for the spread of EVs as it provides a safe and convenient way to charge the vehicles. When wireless power transfer is achieved, the process the process of charging the devices will be made a lot more convenient as we do not have to plug the cord into the socket. Furthermore, as power can be constantly transferred to the vehicles, the battery size can be reduced. Also, the danger of being electrocuted due to the wear and tear of an old cord, or rain will be avoided as the process of handling the power cord is unnecessary, thus making the charging process safer. To achieve wireless charging, the wireless power transfer system must satisfy these three conditions: high efficiency, large air gaps, and high power.

The transfer efficiency between a transmission coil and a reception coil for wireless power transfer via magnetic resonance is a function of the orientation between the coils. When two coils share a single axis, the transfer efficiency is maximal, but otherwise the efficiency becomes lower. In this work, a wireless power transfer system via magnetic resonance using a transmission coil array is proposed to improve the transfer efficiency. The transmission coils of the array are excited with appropriate phase weights by transmission circuit, according to the orientation among the transmission coils and the receiving coil. The effect of the proposed system is confirmed by simulation by a method of moment and measurement using a vector network analyzer.

In the present work, the usage of a magnetic resonance to increase the efficiency of wireless power transferis studied. Analytical calculations and numerical simulations of the proposed magnetic resonance and its impact on power transfer efficiency are presented and supported by experimental measurements.

Proposed Wireless Power Transfer System

The wireless power transfer system involves resonating two antennas with identical self resonance frequency (13.56MHz) using a high frequency power source. The power is transmitted through magnetic resonant coupling in between the two antennas at the resonance frequencies. The power transferred is rectified and used to charge energy storage mediums such as batteries and electric double layer capacitors (EDLC). As stated above, this research focuses on the transmitting part of the system, and the load of the system is set at 50Ω. Under normal circumstances, the coupling factor k (affected by the air gap) and the load (50Ω in this case) are variable and unknown. Only the voltage, current and power reflection ratio can be measured in the power transmitting side of the system. In this system, a directional coupler is inserted before the transmitting antenna to measure the reflected power in between the antennas. The measured values are input into a computer (PC) which is used to control the parameters of the IM circuit. The IM circuit functions as a tuner to change the characteristics of the antennas so that the resonance frequency can be adjusted to the frequency of the power source. This can be achieved by tuning the parameters so that the reflected power ratio measured by the directional coupler reaches its minimum

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