| This paper mainly solves the problems of the service life and transmission efficiency of the power supply side in the wireless power transmission system.Aiming at the sudden change of input current of the traditional single-tube inverter parallel resonant wireless power transmission transmitter circuit,a variable topology single-tube parallel resonant wireless power transmission transmitter circuit is proposed.Firstly,by comparing and analyzing four kinds of inverter circuits,a single-tube inverter circuit is selected.The modeling analysis of the four compensation methods shows that the compensation capacitance of the parallel-parallel resonant circuit is easily affected by mutual inductance and load.This circuit is often used in scenarios where the charging distance is fixed and the load is stable,such as power supply for portable devices,power supply for human implanted electronic devices,etc.Then the two topologies are analyzed,and the resonant inductance at the transmitter and receiver of the system is based on the fundamental wave of 200 k Hz frequency for power transmission.In the traditional topology,the input current suddenly becomes zero when the circuit resonates,resulting in a large proportion of the harmonics of the transmitter circuit.A large number of harmonics cause additional loss to the switching tube,increase the reactive power of the system and reduce the transmission efficiency.The equivalent circuit model is analyzed theoretically,and the input current formula is obtained.The simulation model was built using MATLAB/Simulink and the fast Fourier transform of the input current was performed at the switching frequency of 200 k Hz.The harmonic content of the traditional topology input current is 101.31% at 200 k Hz,and the harmonic content of the variable topology transmitter circuit is 18.83% at 200 k Hz.Combined with the above analysis,the variable topology circuit can improve the system efficiency by improving the input current and reducing the harmonic content in the circuit.Next,the input current ripple is analyzed.In the single-tube inverter circuit,the input current inevitably has a ripple,and the magnitude is positively related to the output power.The current ripple reduces the life of the power supply on the power supply side and affects the system stability.Aiming at this problem,the staggered parallel mode is adopted to suppress the ripple of the input circuit.Two-channel 180° parallel phase-shifting and threechannel 120° parallel phase-shifting wireless power transmission inverter systems are built using MATLAB/Simulink.In static mode and load mode,it is found that the traditional topology has little effect on the input current ripple suppression,and the variable topology inverter system has obvious suppression effect after phase-shifting.Finally,the hardware design is carried out.A two-channel 180° phase-shifting parallel resonance wireless power transmission experimental platform and a three-channel 120°phase-shifting parallel resonance wireless power transmission inverter system experimental platform were built to verify the correctness of theoretical analysis and simulation analysis.The overall transmission efficiency of the system can reach about 80% when the input voltage is 12 V and the output power is 27W. |
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