A Square Four-coil Multi Load Wireless Charging System With Load Isolation Characteristics

Magnetically coupled resonant wireless power transfer(MCR-WPT)technology has gradually been widely used in social life due to its convenience,high efficiency,safety and reliability.For example,this technology has been widely used in terminal equipment such as smartphones and notebook computers,and in industrial manufacturing,and has shown very broad development prospects.At present,wireless charging of multiple devices within a certain threedimensional space at the same time is one of the research hotspots of WPT.This paper mainly studies the design method of a three-dimensional coil that generates a uniform magnetic field in the area when the effective charging range is a cuboid shape,and the multi-load MCR-WPT system based on the three-dimensional coil.The research contents are as follows:(1)The main parameters of the MCR-WPT system are described in detail,and two basic analysis theories are described,namely circuit theory and coupled mode theory.(2)For a cuboid space with any ratio of length,width and height,a complete set of uniform magnetic field coil design process is given.Using this method,the appropriate number of coils can be selected according to the ratio of length,width and height,and a cuboid uniform magnetic field coil that meets the requirements can be designed.Then,starting from the cuboid four-coil,the internal magnetic field distribution of the cuboid four-coil is studied,and the uniformity parameter is introduced to examine the uniformity of the magnetic field.(3)A multi-load wireless charging system with load isolation characteristics is given by using square four-coil as the transmitting coil and combining with the K converter.The transmission principle of its load-independent constant voltage output is clarified,and the simulation verification is carried out by ADS simulation software.(4)The experimental platform of the MCR-WPT system with the square four-coil as the transmitting coil was built,and the invariance of the load voltage of the single receiving end at different locations in the effective charging area was verified to verify the internal magnetic field of the square coil.Then,through the K-converter compensation circuit at the transmitting end,a multi-load wireless charging experimental platform with constant voltage output independent of the load is realized.