| With the intensification of eco-environment problem and the shortage of fossil fuels, a growing number of electric vehicles appear as green vehicles in people’s lives. However, the charging problem of electric vehicles has troubled people for long. This paper presents a wireless power transmission system charging for super capacitor tourist vehicles. Compared with the conventional contact charging system, the new system is more secure, beautiful, and convenient.Firstly, theoretical analysis is conducted for the system. Based on mutual inductance coupling model, the equivalent circuit model of wireless charging system for super capacitor is established, and the expression of transmission power, efficiency and super capacitor charging current is derived. Analysis the influence of super capacitor voltage variation on the charging current and Buck circuit duty cycle.The internal ralationship of mutual inductance, DC bus voltage, Buck circuit duty cycle and charging current is derived. Analysis the influence of mutual inductance on system transmission power and efficiency. For the frequency bifurcation phenomena existing in the system, the paper presents a novel calculation method of bifurcation frequency and critical load. For the problem that the charging current varies with super capacitor voltage, PI control strategy is adopted to adjust Buck circuit duty cycle to keep charging current constant.Secondly, circuit simulation reasearch of system is conducted. Based on simulation tool Pspice, the influence of the DC bus voltage, super capacitor voltage, mutual inductance and Buck circuit duty cycle on super capacitor charging current is simulated. Simulations of resonant frequency’s influence on charging current and operating frequency on system stability are conducted. In the end, frequency bifurcation phenomena’s influence on transmission power, efficiency and are charging current is simulated.Thirdly, magnetic coupling mechanism simulation is conducted. Based on finite element simulation software Ansoft Maxwell, optimize magnetic coupling mechanism’s design. First, analysis the effects of different magnetic core structure on a single coil, and from the point of improving space utilization, point out the superiority of the square planar core. Analysis offset tolerance ability of different secondary magnetic core structure and offset’s influence on inductance, mutual inductance, coupling coefficient. The influence of turns and size is simulated to design the coil. Offset tolerance ability is analyzed when primary side and secondary side is asymmetrical. Finally, the simulation data of present magnetic coupling mechanism is analyzed.Finally, the paper shows experiment results to varify theory and simulaiton. |
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