A NEW INTEGRATION METHOD FOR AN ELECTRIC VEHICLE WIRELESS CHARGING SYSTEM USING LCC COMPENSATION
Abstract
There is a need for charging electric vehicles (EVs) wirelessly since it provides a more convenient,reliable, and safer charging option for EV customers. Awireless charging system using a double-sided LCCcompensation topology is proven to be highly efficient;however, the large volume induced by the compensationcoils is a drawback. In order to make the system morecompact, this paper proposes a new method to integrate thecompensated coil into the main coil structure. With theproposed method, not only is the system more compact, butalso the extra coupling effects resulting from theintegration are either eliminated or minimized to anegligible level. Three-dimensional finite element analysis(FEA) tool ANSYS MAXWELL is employed to optimizethe integrated coils; and detailed design procedures onimproving system efficiency are also given in this paper.The wireless charging system with the proposed integrationmethod is able to transfer 3.0 kW with 95.5% efficiency(overall DC to DC) at an air gap of 150 mm
EXISTING SYSTEM:
Coils are the essence of an inductive based wireless chargingsystem. They determine the power transfer capability andtransfer efficiency. One important property of the coils is thegeometry as it closely relates to the coupling coefficient of thecoil structure and the quality factor of each coil. Reference gives the design and optimization procedures for circular coilsand demonstrates a 2 kW 700-mm-diameter pad. Reference [9]presents a flux-pipe coil structure and claims that a chargingsystem can transfer 3.0 kW power with 90% efficiency at an airgap of 200mm. However, the flux-pipe coil conductsdouble-sided flux paths and one of the flux paths is wasted. Inorder to solve this problem, a bipolar coil structure is developedin . The bipolar coil structure offers high efficiency andgood misalignment tolerance. An 8 kW wireless chargingsystem is built and tested in. With the optimized bipolarcoil structure, the charger can transfer power with 95.66%efficiency when fully aligned and 95.39% efficiency with a 300mm horizontal misalignment. More recent research on coildesign can be found in. The researchers embed a coplanarcoil into the primary coil system to improve the overallcoupling of the system, which increases the efficiency with theSS compensation topology. Compensation topology is another important aspect in awireless charging system as it increases the power transferability, minimizes the VA rating of the power source, and helpsachieve soft switching of the power electronics devices.There are four basic compensation topologies: SS, SP, PS, andPP where the letters “P” and “S” stand for the way how theresonant capacitor is connected to the coil, i.e., “P” representsparallel connection and “S” represents series connection. Moreadvantageous compensation topologies are put forward in. The double-sided LCC compensation topology isoutstanding since not only is its resonant frequencyindependent of coupling coefficient and load condition, but alsoit is highly efficient. However, one drawback of thedouble-sided LCC compensation topology is its large volumedue to the compensated coils.
PROPOSED SYSTEM:
To overcome the volume limitation, reference first putsforward the idea of integrating the compensated coil into themain coil system. The authors integrate a bipolar compensatedcoil into a bipolar main coil system. As it is shown in Fig. 1,five extra coupling effects appear after the integration and thecoupling effect of the two coils at the same side of the wirelesscharging system are studied. A 6 kW wireless charging systemwith 95.3 % efficiency was designed and tested in. Furtherdetailed analysis on both the coupling effect of the same-sidecoils and the coupling effect of the cross-side coils can be foundin. successfully make the systemmore compact and highly efficient; however, the method ofintegration complicates the design of a wireless chargingsystem using double-sided LCC compensation topologies. In order to simplify the design and analysis while keep the advantages of compactness and high efficiency, this paperproposes a new integration method for a wireless chargingsystem using LCC compensation topology. In this method, thefive extra coupling effects are either eliminated or minimized toa neglected level, which greatly simplifies the design andanalysis. Additionally, a new method of improving systemefficiency is given. Consequently, the system keepsoutstanding performance and is able to deliver 3.0 kW powerwith 95.5% DC-DC efficiency at an air gap of 150 mm.
CONCLUSIONS
This paper gives a new integrated method of a wireless charging system using double-sided LCC compensationtopology. With the compensated coils integrated into the maincoil structure, the system becomes much more compact. Theproposed compensated coil design further eliminate orminimize the extra coupling effects to a negligible level,making it more straightforward to design a wireless chargingsystem using the double-sided LCC compensation topology.The detailed design procedures to improve system efficiencyare also introduced. Both the 3D FEA simulation results and theexperimental results verify the proposed idea. The compact andhighly efficient wireless charging system is able to deliver 3.0kW at a DC-DC efficiency of 95.5% with an air gap of 150 mmwhen fully aligned. Our future work is to install the designed wireless charger ona vehicle. In order to achieve that, we will not only analyze theadditional power loss resulted from ambient objects, such as theEV chassis and the steels buried in the ground, but also optimize the ferrite plates so that minimum ferrite bars areemployed to deliver the same amount of power withcompetitive efficiency.
REFERENCES
[1] J H. Hertz, Dictionary of Scientific Biography, vol. VI. New York:Scribner, pp. 340 -349.
[2] N. Tesla, “Apparatus for transmitting electrical energy,” U.S. Patent 1119 732, Dec. 1914.
[3] W. C. Brown, “The history of power transmission by radio waves,” IEEETrans. Microw. Theory Tech., vol. MTT-32, no. 9, pp. 1230-1242, Sep.1964.
[4] J. Garnica, R. A. Chinga, and J. Lin, “Wireless power transmission: fromfar field to near field,” Proceedings of the IEEE., vol. 101, no. 6, pp.1321-1331, Apr. 2013.
[5] A. Kurs et al. “Wireless power transfer via strongly coupled magneticresonances,” Science, vol. 317, no. 5834, pp. 83-86, Jul. 2007.
[6] R. Wu, W. Li, H. Luo, J. K. O. Sin, and C.P. Yue, “Design andcharacterization of wireless power links for brain-machine interfaceapplications,” IEEE Trans. Power Electron., vol. 29, no. 10, pp.5462-5471, Jan. 2014.
[7] D. Ahn and P.P. Mercier, “Wireless power transfer with concurrent 200kHz and 6.78 MHz operation in a single transmitter device,” IEEE Trans.Power Electron., vol. PP, no. 99, pp. 1-13, Sep. 2015.
[8] M. Budhia, G. A. Covic, and J.T. Boys, “Design and optimization ofcircular magnetic structures for lumped inductive power transfersystems,” IEEE Trans. Power Electron., vol. 26, no. 11, pp. 3096-3018,Apr. 2011.
[9] H. Takanashi, Y. Sato, Y. Kaneko, S. Abe, and T. Yasuda, “A large airgap 3 kW wireless power transfer system for electric vehicles, ” in EnergyConversion Congress and Exposition (ECCE), 2012 IEEE, 2012, pp.269-274.
[10] M. Budhia, J.T. Boys, G. A. Covic, and C. Huang, “Development of asingle-sided flux magnetic coupler for electric vehicle IPT chargingsystems,” IEEE Trans. Ind. Electron., vol. 60, no. 1, pp. 318-328, Sep.2011.