Abstract
To increase the usage of electric vehicles (EV), a safe and convenient method to charge the vehicles is essential. Recently, an efficient mid range wireless power transfer that uses magnetic resonant coupling, WiTricity, was proposed, and has received much attention due to its practical range and efficiency. Studies show that the resonance frequency of the antennas changes as the gap between the antennas change. However, when this technology is applied in the MHz range (which allows small sized antennas), the usable frequency is bounded by the Industrial, Science, Medical (ISM) band. Therefore, to achieve maximum power transmission efficiency, the resonance frequency has to be fixed within the ISM band. In this paper, the possibility of using impedance matching (IM) networks to adjust the resonance frequency of a pair of antennas at a certain distance to 13.56MHz is studied. The simulations and experiments show that the IM circuits can change the frequency to 13.56MHz for different air gaps, improving the power transfer efficiency. Experiments also show that IM can be achieved just by observing and minimizing the reflected wave.
Highlights
Wireless power transfer is essential for the spread of electric vehicles (EV) as it provides a safe and convenient way to charge the vehicles
The equivalent circuit used in the simulations and experiments are shown in Fig. 8a, where an impedance matching network is inserted in between the power source and the transmitting antenna
The results show that the efficiency can be increased in these situations, potentially extending the gap that allows high efficiency power transfer further. (Fig. 10) there should be a physical limit to which this matching circuit can work, as the gap should not be able to extend infinitely
Summary
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. The wireless power transfer system must satisfy these three conditions: high efficiency, large air gaps, and high power. The electromagnetic induction method has a short range [3], and the microwave power transfer has a low efficiency as it involves radiation of electromagnetic waves. A highly efficient mid-range wireless power transfer technology using magnetic resonant coupling, WiTricity, was proposed. It is a system that transfers power in between two resonating antennas through magnetic coupling. It satisfies all three conditions to make wireless charging possible as it has a high efficiency at mid range. (Approximately 90% at 1m and 50% at 2m [1] at 60W )
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
