| Wireless Power Transmission technology stands out among many charging methods by virtue of its advantages of simple operation,safety and stability.Aiming at optimizing the transmission efficiency of electric vehicle WPT system,this paper analyzes and studies the main circuit topology optimization and impedance matching network.Firstly,for the bilateral LCC compensation topology in WPT system,the integrated design and parameter optimization research are adopted.The mutual inductance equivalent model of the system coupling mechanism is established.In this model,the inductance will weaken the transmission performance of the system,which leads to the resonance compensation topology.By comparing and analyzing the output characteristics of different compensation topologies,the bilateral LCC compensation topological structure is selected as the research object.Then a compact integrated coil method is proposed,that is,the bipolar resonant coil is integrated into the unipolar main coil.They use a magnetic core,which effectively solves the problem that the two compensation coils in the bilateral LCC topology occupy a large volume.At the same time,by optimizing the position and aspect ratio of the coils on both sides,the redundant coupling coefficient in the system is eliminated,thereby improving the transmission efficiency of the WPT system.Secondly,this paper combines the compact and highly efficient bilateral LCC compensation topology with the impedance matching network,and proposes the LCC-LCC/DC-DC system.In view of the fact that impedance matching is an important means to improve the efficiency of WPT,considering that the equivalent load of the vehicle battery will change during the actual wireless power transmission process,this paper proposes to use DC-DC converter to achieve impedance matching and keep the system at the optimal efficiency point by adjusting the duty cycle.Buck-boost converter is used to realize the impedance matching adjustment in a wide range,and double closed loop PI control strategy is used to realize the control and regulation of the whole system.The simulation results show that the proposed method is feasible,which can realize wide impedance matching and optimize the transmission efficiency of the system.Finally,the experimental platform of electric vehicle wireless power transmission based on DSP is designed,and the hardware and software modules of the system are designed in detail.The experimental results show that the comprehensive scheme proposed in this paper can adjust the equivalent load impedance in a wide range,so as to achieve the optimization of transmission efficiency.Moreover,when the two sides of the WPT system are not perfectly aligned,high efficiency of power transmission can still be maintained. |
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