Research And Design Of Wireless Power Supply Based On Parity Time Symmetry Principle

Wireless power transfer technology has a long history of development,which can be traced back to Tesla’s vision of long-distance wireless power transfer.Today,wireless power transfer has gradually entered people’s field of vision.The implementation of wireless power transfer technology can be divided into magnetic coupling,electric field coupling,and microwave transmission.These methods have their own advantages and are used in different occasions according to their characteristics.In order to understand the mechanism of wireless power transfer from multiple perspectives,researchers have modeled the wireless power transfer system in a variety of ways,including mutual inductance circuit models,two-port network equivalent models,and coupled mode models.The principle of parity time symmetry was discovered in quantum mechanics and was of great significance when studying non-Hermitian Hamiltonian systems.It also provides solutions to a series of problems in optical coupling resonators.Because the coupling cavity in optics is similar to the electrical and magnetic coupling cavities in wireless power transfer,the principle of parity time symmetry is applied to wireless power transfer in this paper,and a wireless charging power supply based on the equivalent negative resistance of the receiving end parity time symmetry is proposed.In response to market demand,this paper designs a set of 40 W constant power charging device,which can charge small and medium wireless charging devices such as sweeping robots and small drones.The main content of this thesis is as follows:First,it summarizes the research background of wireless power transfer technology,the research process at home and abroad,and the current engineering application background of wireless power transfer.And it points out the relationship between the principle of parity time symmetry and wireless power transfer technology,as well as the research done by predecessors,and explains the research significance of this thesis.Then the theory of coupled mode model is explained,combined with the commonly used topology in wireless power transfer system,and the principle of wireless power transfer is analyzed using coupled mode model theory,and system energy characteristics and its frequency characteristics are pointed out.Then,the phenomenon of parity time symmetry in electricity is explained,the parity time symmetry coupled mode model proposed in this paper is given,and its circuit model is designed and analyzed.Then,for the situation that the output power changes,when the resistance value changes during the load charging process,a DC-DC digital voltage regulator is added at the back of the coupling cavity to realize the constant power charging of the lithium battery.After that,the coupling coil is selected and designed.Finally,the PSIM simulation platform is used to simulate and verify the parity-time symmetric wireless charging power supply I designed.Then,based on the completion of theoretical analysis and simulation verification,software and hardware design and corresponding parameter design are given,and an experimental platform for experiments is built.A 40 W wireless charging power supply prototype is built successfully,which verifies the proposed the feasibility of wireless power products.The experimental results of the prototype test show that this device has the advantages shown by the coupled cavity based on the principle of parity time symmetry: the control response speed is fast,the receiving end position is not sensitive,and the constant power transmission of the coupled cavity can be realized within a certain range.Moreover,it solves the phenomenon of power rise at the receiving end in the asymmetric area of parity time,and improves the range of constant power transfer;at the same time,it realizes the Zero Voltage Switch of the inverter MOS tube,which reduces Switching loss;it also improves the stability of the system when the load changes during charging.