Modeling And Analysis Of Omnidirectional Wireless Power Transfer System Based On PT Symmetry Principle

The wireless power transfer technology has undergone rapid development in recent years,has been thoroughly studied,and is increasingly mature.At the same time,it is also facing many opportunities and challenges.The traditional wireless power transfer system is sensitive to changes in the coupling coefficient.When the position of the coil changes,it is easy to cause problems such as low charging efficiency and inconvenience in use.This requires that the actual wireless power transfer system has strong anti-displacement and transmitting direction shift performance,and can actively combat the adverse effects on the system caused by the change of the coil's position state in a certain space.Therefore,this paper proposes a high-efficiency,low-cost omnidirectional wireless power transfer system based on parity-time symmetry theory,which is based on the requirements of high position freedom and strong practicability.The main research contents of this paper are as follows:First,the development status of omnidirectional wireless power transfer technology is described,the limitations of using existing wireless power transfer system to achieve omnidirectional power transfer are discussed,and the feasibility of omnidirectional wireless power transfer needs to be explored from the level of power transfer mechanism,and then the significance and purpose of this paper are put forward.Then,the definition of parity time symmetry theory and the construction method of negative resistance are explained,and then the physical meaning of its application in wireless power transfer is discussed.The basic theory of coupled mode is described,and the relationship between the coupled mode equations and the circuit parameters in the SS type wireless power transfer system is explained with two LC coupled oscillator circuits.Next,considering the change of the position state between the transmitting and receiving coils,adding the direction change amount to the static system where the coils are axially symmetrically placed,and establishing a two-coil SS-type WPT dynamic system time-varying coupling mode model based on the coil direction offset angle,and the transmitting characteristics are analysed and researched.Therefore,the PT symmetry principle is proposed to realize wireless power transfer in all directions.In consideration of the fact that metal foreign objects are likely to adversely affect the WPT system in practical applications,the reflection of metal foreign objects in the transmitting characteristics of the WPT system is studied from three aspects of the transmitting coil parameters,the coupling magnetic field distribution,and the system resonance frequency.Finite element simulation analysis,and further explore the practicality of WPT system.Finally,the theoretical analysis results are used to design the various links of the proposed system,the implementation process of the negative resistance and the design method of the coupling coil are explained,and the simulation model and experimental prototype of an omnidirectional wireless power transfer system with an output power of 150 W are established.It is proved that the WPT system based on the PT symmetry principle can realize omnidirectional wireless power transfer regardless of the coil position within a certain range of space,and the transmitting efficiency is as high as 90% and remains unchanged.