| Wireless power transfer(WPT)is a new type of energy transfer technology,which is a hot research field at present.It can overcome the shortcomings of traditional power transfer methods relying on wire,and therefore has a wide range of practicality.However,compared with the wired transfer,there is still a certain gap between the transmission power and transmission efficiency,which is also an important factor that hinders the popularization and application of this technology.In response to this problem,this paper combines high temperature superconductor(HTS)with wireless power transfer considering the characteristics of low loss and high current density of HTS.In this paper the relationship between various electrical parameters are theoretically analyzed firstly,and then the working characteristics of the HTS coil are researched,the coupling mechanism and characteristic of the superconducting wireless power transmission system under different parameters is discussed finally.The details are as follows:(1)Based on the Air-core transformer equivalent circuit,the basic working principle of the wireless power transmission system is analyzed.The transmission power and transmission efficiency of the system are theoretically deduced,the relationship between the parameters affecting the transmission power and transmission efficiency of the system is summarized,and the advantages of introducing superconducting technology to wireless power transmission systems are explained.Meanwhile,through the analysis of the structure of the HTS coil and the generated magnetic field,the staggered pancake HTS coils structure is more suitable for a wireless power transmission system.(2)Based on the H-formulation,the HTS coil is simulated,and the variation of the magnetic field distribution,current density distribution and AC loss of the HTS coil with the working current amplitude and frequency is researched.It is concluded that the average AC loss has an exponential relationship with the current amplitude and is almost proportional to the frequency.The three-dimensional modeling method of the HTS coil is introduced by taking the racetrack coil as an example,and the crosssectional magnetic field distribution at different positions is compared to reflect the significance of three-dimensional modeling.(3)The homogenization method is introduced,and through the calculation of AC loss,the error of the homogenization method is very small.Based on the result,the twodimensional axisymmetric model of the superconducting wireless power transmission system is established by the H-formulation and the homogenization method.The distribution of magnetic field,current density and critical current density are analyzed,and the effects of the difference of loads,frequencies,and different axial coil gap on the AC loss and transmission efficiency are discussed.Then,a three-dimensional model is established to analyze the influence of radial coil spacing on the AC loss and transmission efficiency of the system.The results show that there is the best load resistance and the best operating frequency to maximize the transmission efficiency,and the transmission efficiency is maximized when the primary and secondary sides are coaxial,and the greater the pancake gap,the lower the transmission efficiency. |
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