Research On Wireless Power Transmission Technology Based On Multi-load

With the development of society,WPT technology(Wireless Power Transfer,WPT)has made a great progress and can be used in many cases.In current research,the single load inductive coupling technology is widely researched,but it adopts "point to point"power supply structure,which requires the transmitter coil and receiving device aligned on a certain location and can't move freely.Otherwise,the efficiency and the power will be greatly reduced.This structure has some shortages in the practical applications,such as the load position tolerance is low,the leakage of electromagnetic field is serious,the number of power supply loads are limited,which is not suitable for multi-load application cases.In this paper,the transmission characteristics,resonant compensation network and magnetic coupling structure of multi-load WPT system are deeply studied to overcome the limitations of existing technologies.The main content is as following:In the research of transmission characteristics of WPT system,this paper analyzes the characteristics of single-load and multi-load system,studies the influence of compensation capacitance,magnetic coupling parameters,system operating frequency and load variation in WPT system.The general method of WPT system modeling method is studied by the theoretical analysis.This method can be applied to WPT system analysis with different structures and parameters.In the research and design of compensation network,this paper analyzes the transmission characteristics of four basic compensation structures.Base on this,a new compensation method based on leakage inductance compensation is proposed.According to the requirement of external characteristic(such as gain,constant voltage,constant current,resistance,etc.)to obtain compensation network parameters,improve the flexibility of the design effectively.Especially in the cases with low coupling coefficient.In this application,the compensation method can greatly improve the power transmission capacity of the circuit,and improve the performance of magnetic coupling system.It has good effects in the applications with single load and multi-load WPT system with fixed load position.Meanwhile,this paper analyzes the T-compensation network structure,and studies the LCC and CLC resonant compensation methods which make the transmitting coil keep a constant current.The basic principle and transmission characteristics of the two compensation methods are analyzed.So that the resonant compensation method can be effectively applied to the multi-load WPT system,which the load can move freely.In the modeling and optimization of the magnetic coupling system,a new magnetic coupling structure is designed,including the structure of transmitter coil and the receiver coil.The new transmitter coil can produce a uniform magnetic field on the surface,so that the receiving device can pick up the similar magnetic field energy at any position on the platform,besides it has a smaller magnetic field leakage.In the new receiving coil design the multi-winding structure is adopted,which can pick up the energy of magnetic field in any direction in the space.It improves the utilization of magnetic energy and the coupling coefficient.Based on the optimization of the coupling coefficient and the system efficiency,the new magnetic coupling structure are designed to enhance the position robustness,reduces the leakage of the electromagnetic field and increases the efficiency.Finally,based on the theoretical analysis above,a WPT prototype based on multi-load is designed.The input voltage are 220V/50Hz,the output power are greater than 15W with four loads maximum,the power transmission distance are 0 to 5mm,the system efficiency are about 51.8%with one load and 57.7%with multi-load.This prototype possess a good position robustness and low electromagnetic leakage.The experimental results prove the validity and feasibility of the theoretical analysis.