Research On Multi-relay And Multi-receiver Wireless Power Transmission Technology Based On Magnetic Resonance Coupling

Wireless power transfer technology can realize contactless charging,which has great advantages in terms of charging safety and flexibility,especially in some smart devices and special fields.Since Nikola Tesla proposed the concept of wireless power transmission,scholars have invested a lot of research in the field of wireless power transfer technology,and now it has gradually become a hot research topic in academic research.Among them,magnetic resonance coupled wireless power transfer technology is the most widely studied,because it has the advantages of higher transmission efficiency,while taking into account the medium transmission distance,and the power can achieve the order of kilowatts.At present,the research of this technology is still more in the study of one-to-one power transmission system.And the research of one-to-multiple receivers is less,especially the analysis of the transmission state and important parameters of the system has not been systematically studied.In addition,the transmission distance of the magnetically coupled resonant wireless power transmission technology is still limited by the size of the coil,which makes it impossible to achieve a longer transmission distance and higher efficiency under the condition of limited size.This is also a difficult problem of the practical application of the technology.Based on the investigation of a large number of domestic and foreign literatures,this paper mainly studies and designs the magnetic resonance coupled multi-relay multi-receiver wireless power transmission system.The important parameters of the transmission system are studied respectively: transmission power,transmission efficiency and their characteristics of the situation as the number of receivers and the location of the relay change.High efficiency inverters,high efficiency transceiver coil,relay coil,optimal impedance matching circuit and various rectifier voltage regulator circuits are designed.The transmission theory and system design have been deeply studied.The main research contents and innovations of this paper are as follows:(1)The low frequency MRCPT system is proposed.The system composition is different from 6.78 MHz and 13.56MHz(ISM band)energy transmission system.The transmission source uses inverter power supply,which can effectively improve conversion efficiency and transmission power.The performance is good and the cost is low.The paper summarizes and contrasts their performance advantages.(2)The magnetic resonance coupled wireless power transfer system is analyzed by circuit theory.The coupling coefficients between coil and coils are extracted by HFSS and Maxwell.The circuit simulation is carried out in ADS software to study the transmission state of the system,including frequency characteristics,load characteristics and distance characteristics.Through the repeated optimization of simulation and experiment,the optimal transmission state of the system is realized.The advantages of the transmission distance after adding the relay coil are compared.The effects of the different positions of the relay coil in the axial position and the lateral position on the transmission efficiency is studied.For the multi-receiver system,the capacitor allocation method with different positions at different positions and different loads of receivers is proposed,and the correctness of the method is verified by experiments.(3)The variation law of the optimal load in the series and parallel resonance state of the receiver is studied and the generalized conclusion is obtained.The method of transforming arbitrary load to the optimal load of the system is proposed.The correctness of the method is verified by simulation and experiment.From the theory of multi-receiver circuit,the mathematical expressions of the receiving power and system power distribution ratio of each receiver are derived,and the influence parameters are clarified.By extracting the coil coupling model,the circuit simulation and capacitance matching are carried out to achieve arbitrary power allocation at different receiver.(4)This paper studies and designs a full-bridge inverter power supply,whose working frequency is 1KHz~1MHz,and the maximum output power can reach 300 W.The power output control can be realized by self-made or external signal generator,and the conversion efficiency is over 95%.Two rectifier voltage stabilization circuits with different power levels are developed.The transmitter,transmission coil and receiving circuit are combined in the refrigerator to build and test a multi-relay and multi-receiver MRCPT system.