High Speed Signal Transmission Technology Based On Partial Power Channel For ECWPT System

Electric energy needs to be transmitted through electric energy transmission medium.At present,wire is often used to transmit electric energy.Electric-field Wireless Coupled Power transfer(ECWPT)is one of the new technologies which uses high frequency alternating electric field as power transmission medium to transmit electric energy and it effectively reduces the interference of power transmission line to electric equipment.The ECWPT system has many advantages as follows: the coupling electrode is simple and thin,and the shape is flexible;the electric field is limited between the coupling electrodes,and the electromagnetic radiation to the surrounding environment is very small;no eddy current loss occurs when a metal exists between or around the coupler;power can be transmitted through metal obstacles.Therefore,the ECWPT system has gradually attracted the attention of experts and scholars.In the practical application of the ECWPT system,the robustness and power efficiency of the ECWPT system can be improved by forming a real-time data interaction between the transmitter and the receiver.In some applications,it is necessary to realize the signal data interaction.At present,many researches have focused on wireless power and signal parallel transmission in Inductive Coupling Power Transfer(ICPT)system,and some methods have been proposed.But at the same time,the research of parallel transmission technology of electric energy and signal in ECWPT system is relatively less,and the existing solutions also have some problems such as the transmission speed is low,which is limited in the application of systems with high requirements for real-time.According to the characteristics of ECWPT system,in order to further improve the speed of signal transmission,this paper proposes a power and signal parallel transmissions method by Orthogonal Frequency Division Multiplexing(OFDM)modulation and demodulation technology for ECWPT system based on partial power channels.The paper analyzes the power transformation circuit,resonance compensation network and coupling mechanism to choose the power transmission topology of the system.The power transmission topology is determined based on the advantages and disadvantages of the commonly used power transformation circuit,the influence of signal on the resonance network and the simplicity of coupling mechanism.The final power transmission topology is based on the ECWPT system compensated by two LC networks.By adding an additional pair of signal transmission plates,the power and signal can be transmitted in parallel with the original two pairs of energy transmission plates.Then,several basic signal modulation methods are compared,and the reasons for reducing the signal transmission speed are analyzed.In order to improve the transmission speed,OFDM modulation and demodulation technology is used.According to the determined system topology,it is simplified to the equivalent power transmission topology and the equivalent signal transmission topology.The mathematical expressions of the power crosstalk voltage and the signal pickup voltage are given.At the same time,the influence of the signal plate parameters on the transmission speed is analyzed.Combined with the principle of the modulation and demodulation circuit and the constraints of the power of power transmission,the parameter design method of the system is given.Finally,simulation is verified by Matlab/Simulink,and according to the derived parameter design method,multiple sets of system parameters are designed.The independence of the established equivalent electric energy transmission channel and signal transmission channel topology,that is,whether the crosstalk between electric energy and signal affects the system performance,is verified.The size of signal plate and signal transmission speed are given through simulation.At the same time,the system experimental prototype is built to verify the theoretical model and the parallel transmission characteristics of energy and signal.The experimental prototype realizes stable parallel transmission of energy and signal and the signal transmission rate is around 80 Mbps.