| With the popularization of electric equipment,the requirements for battery charging technology are getting higher and higher.Because traditional cable charging methods have problems such as high maintenance costs,prominent safety hazards,and low intelligence,it is an inevitable trend that a Wireless Charging Technology(WCT)with good flexibility,high safety,and low maintenance cost is applied to mobile electric equipment.In view of the current WCT existing technical problems such as transmission power,transmission distance,transmission efficiency,traditional WCT cannot meet the requirements of intelligent,fast,efficient,and stable charging tasks for mobile electric equipment.Therefore,exploring and developing a reliable and efficient Magnetic Resonance Coupling Wireless Charging System(MRCWCS)has important engineering significance and value.This dissertation is aimed at the problems of the transmission mechanism compensation network detuning,the offset of the transceiver coil,and the sensitivity of the load characteristics during the wireless charging of the system,a control strategy is proposed to realize the system’s active impedance matching and stable operation of the full load range by controlling the transmitting mechanism through fixed frequency and constant duty cycle,adding a DC/DC converter to the receiving mechanism and controlling through variable frequency and constant duty cycle.Then,based on the theoretical analysis of the system,the design of hardware and software,a 500W magnetic resonance coupling wireless charging system prototype was built,and the battery load constant voltage and constant current charging test experiment was completed.Firstly,introduced the selection of system power topology;the impedance matching characteristics of the LCCL-S compensation network are analyzed through the circuit equivalent theory,and the optimal operating frequency point to realize the characteristics of Zero Voltage Switch(ZVS)and Zero Phase Angle(ZPA)is given;In addition,the half-bridge LLC circuit is selected as the topological structure of the DC/DC converter of the receiving mechanism,and its working principle and mechanism are analyzed in detail.Secondly,based on the modeling and analysis of the compensation network of the transceiver mechanism,a detailed theoretical design of the resonant device parameters is carried out;According to the theoretical calculation value of the resonant device,Matlab is used to model and analyze the relationship between the resonant inductance L_p,the coupling coefficient k,the change of the load R_Land the output power or transmission efficiency to verify the feasibility of the theoretical analysis of the system.Then,according to the system design indicators,the PFC circuit,the compensation network of the transceiver mechanism,and the half-bridge LLC circuit are selected and designed,and introduce in detail the design of the hardware and software of the system control part.The hardware part mainly includes DSP controller and peripheral circuit,driving circuit,current and voltage differential sampling circuit,auxiliary power circuit design;The software part mainly includes related system initialization configuration and soft start,digital PID and battery load three-stage charging control algorithm design.Finally,simulate the system on Saber software and verify that the system is working in the full load range,using fixed frequency control in the transmitting mechanism and adjusting the operating frequency of the half-bridge LLC circuit in the receiving mechanism,the feasibility of realizing the switch tube ZVS and anti-coil offset of the transceiver mechanism.Use HFSS three-dimensional electromagnetic simulation software to simulate the magnetic field distribution of the double-layer structure of the same diameter and the large and small double-layer structure of the transmitting and receiving coil,The battery load constant voltage and constant current charging experiments under different conditions were carried out on the experimental prototypes built.By collecting the key experimental working waveforms of the system,the results verified the feasibility and effectiveness of the experimental prototype design and theoretical analysis of the system. |
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