| The emergence of Electric Vehicles is an important revolution in the field of transportation.The introduction of Wireless Power Transfer improves the convenience of Electric Vehicles charging.The interoperability of Wireless Power Transfer of Electric Vehicles means that users can charge with any ground equipment without considering the different manufacturer,different power level,different compensation network and so on.Taking Wireless Power Transfer System as the object,this paper analyzes the interoperability of magnetic coupling mechanism and compensation network.Firstly,this paper introduces the principle of the test method of impedance parameters as the criterion of interoperability,expounds the concept of input impedance,and deduces the expression of reflection impedance based on the theory of reflection impedance.The equivalent model of electric vehicle wireless charging based on mutual inductance model is established,and the theoretical possible trajectory range of reflection impedance in complex plane is deduced.As an interoperability test,impedance parameters need to draw the reference impedance area in advance,and then compare the impedance area of the tested product with the reference impedance area to analyze whether it can fall in the impedance area.If it can,it is considered that the tested product can interoperate with other Ground Assembly(GA)products.Then the interoperability of compensation topology is analyzed.Secondly,in order to verify the proposed method and draw the impedance region diagram,taking 11 k W(WPT3)as an example and referring to the recommended parameters given in SAE J2954,the universal circular GA coil,universal DD coil,circular Vehicle Assembly(VA)coil and Double-D(DD)VA coil are simulated and modeled.The self-inductance and mutual inductance values under different gaps and different offsets are obtained by FEM simulation,The impedance region diagram is drawn and the interoperability based on impedance parameters is determined.In order to verify whether the judgment of interoperability based on impedance parameters is correct,the FEM simulation of coil and Simulink simulation of WPT System are carried out,and the relationship between system transmission power,coupling coefficient,selfinductance and interoperability is analyzed.The conclusion is consistent with the judgment based on impedance parameters,which proves the feasibility and correctness of evaluating interoperability based on impedance parameters.Finally,the interoperability experiment platform of Wireless Power Transfer of Electric Vehicles is built,and the simulation coil is wound,and the impedance region diagram is drawn with the same path as the simulation analysis.The impedance region diagram of different combination coils is compared with the reference region,and it is found that the experimental conclusion is consistent with the simulation conclusion,it is proved that the interoperability testing method based on impedance parameters is feasible and reasonable. |
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