| Wireless power supply technology is a frontier topic in the field of power transmission.This technology has effectively overcome the problems of poor mobility of equipment and exposure of power supply lines and contacts.It is known as one of the "10 science technologies leading to the future".In terms of energy transfer medium and mechanism,three types of electric energy wireless transmission modes are proposed: induction,radiation and coupling resonance.The characteristics of the resonant energy transmission technology based on the strong coupling theory are that the magnetic field is transmitted through the near field with a strong direction and suitable for medium distance transmission,and the transmission efficiency is high,the energy transmission is not affected by the space obstacle(non magnetic),the level of magnetic radiation is not high and it is easy to suppress.This technology also has important application value and prospect in the field of carrier and transportation engineering.In this paper,the WPT technology based on magnetic coupling resonance is selected as the topic.First,after the change of the the air gap distance,the coil radius,the line diameter and the number of coil turns,coupling factor is analyzed by the ANSYS finite element software.Taken the coupling of the solenoid coil with and without iron core as the object,the mesh is divided,and the simulation results of the magnetic force line distribution and the magnetic induction intensity cloud are obtained,which provides the optimization basis for the design of the coil.Secondly,starting from the overall structure of the WPT system,the composition and working principle of the system are analyzed.Taking the transmitting circuit as the research focus,the commonly used transmitting circuit is the LCC type resonant emission circuit,and the high frequency full bridge inverter is a key link of the transmitting part.Although the primary coil voltage can be controlled by the active front end converter to change the DC line voltage,the more direct method is to control the power of the secondary coil through the high frequency inverter.The dead zone of the MOSFET device in the main circuit of the high frequency inverter will cause the cross distortion of the output current wave form,so that the transmission loss of the WPT system will increase.For this reason,this paper adopts a method based on pulse width adjustment to realize dead time compensation to meet the requirements of WPT system,and carries out simulation research and analysis.Third,through the analysis above,it is known that the high frequency alternating current in the resonant network coil is generated by the transmitter inverter.In most inverter topology,in order to produce a certain frequency of the resonant current,the frequency of the switching tube in the inverter is up to hundreds of KHz,and increases with the increase of the resonant frequency of the system.In this way,the switching losses of switch tubes increase.If switching loss exceeds transmission loss,the transmission efficiency of the system will be reduced.In order to alleviate this problem,this paper designs a AC/AC based pulse injection type WPT system transmitter circuit inverter topology.This scheme can significantly reduce the switching frequency of the inverter,and decouple the energy injected into the WPT system with the switching frequency and the load status.Finally,the experiment of magnetic coupling resonant WPT system with high frequency full bridge inverter as the transmitting circuit is designed in this paper.The radio reception of electric energy is realized with the LED lamp as the object.For the pulse injection type WPT system emission circuit topology,this paper uses SIMULINK simulation tool to analyze the current and voltage waveform of input and output current and voltage under each step and current and voltage waveform of each component,which proves the feasibility of the topology,which has a very strong prospect of engineering application. |
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