Research On MISO Wireless Charging Technology Based On Rotating Magnetic Field

In the research of wireless charging technology,it is found that the traditional wireless charging technology with one-to-one structure requires the transmitter coil and receiver coil to be aligned in order to achieve better charging effect,and in practice,the situation that the receiver coil and transmitter coil are not aligned is inevitable.Nowadays,how to achieve multi-directional wireless charging has become a focus of research,so omnidirectional wireless charging technology has been proposed to solve the problem.Multiple Input Single Outout(MISO)is one of the structures used in omnidirectional wireless charging systems,where a rotating magnetic field is generated by a multi-transmitter coil structure,thus providing multiple directions for effective energy transfer.In this paper,the omnidirectionality of the MISO wireless charging system is studied.The smaller the difference in the charging effect obtained when the receiving coil is in different positions,the better the omnidirectionality.In this paper,by studying the relationship between the transmitting coil structure and the generated magnetic field,the transmitting coil structure is optimized and a non-uniform planar spiral coil structure is designed.Using the coil of this structure to build an orthogonal type of MISO wireless charging system can improve the omnidirectionality of the system.The main research of this paper is as follows:(1)Two-to-one orthogonal and three-to-one orthogonal wireless charging systems are analyzed,the principle of rotating magnetic field generation is analyzed,and the excitation source addition scheme for two-to-one and three-to-one wireless charging systems based on rotating magnetic fields is determined.(2)The magnetic field generated by two orthogonal transmitting coils composed of a cylindrical spiral coil and a planar spiral coil were compared and analyzed,and a non-uniform planar spiral coil structure was designed by selecting a planar spiral coil with a more uniform magnetic field distribution and optimizing it.Then the magnetic fields generated by the planar spiral coil and the non-uniform planar spiral coil were compared in the two-orthogonal coil and three-orthogonal coil models,respectively,and the experiments showed that the magnetic fields generated by the non-uniform planar spiral coil were more uniformly distributed.(3)Completed the system resonant network selection.Two-to-one and three-to-one bilateral LCC resonant networks without neglecting the equivalent internal resistance of the loop are analyzed,and conditions are obtained to make the average power output of the system stable and constant when the position of the receiver coil is varied.(4)A simulation experiment platform was built to compare the omnidirectionality of MISO wireless charging system based on rotating magnetic field with three different coil structures,and the experiment shows that the non-uniform planar spiral coil structure designed in this paper has the best omnidirectionality.A MISO wireless charging system was built and tested based on a non-uniform planar spiral coil,and the experimental results show that the system has a small output power fluctuation and good omnidirectionality.