| Electric vehicle (EV) is a new type of environmentally friendly vehicle which is provided power by the car battery. And it is one of the most important ways to reduce mass of fossil energy consumption, cut down environmental pollution and decrease operating cost. EV charging way is divided into two kinds, cable charging and wireless power transfer (WPT). Cable charging mode has many defects to limit the development of EV industry largely, including operation inconvenient, production sparks easily and can’t work in harsh conditions such as the rain and snow weather. WPT is the main development direction of the market today, because this mode can operate easily, there is no contact loss and electric shock risk, and is easy to implement automation.The EV wireless power transfer theory is analyzed in detail, S-S mode and S-P mode are derived particularly, and the accuracy of mode is proved by simulations and experiments in the paper which bases on the electromagnetic induction law and uses resonance and inductively coupled principle. The working state, the parameters of chips and components are designed in detail, and the simulations (PSIM and PSPICE) are implemented to prove the design. At last, a WPT experimental platform are made, and the batteries can be charged by the system. The rationality of design and the correctness of analysis are verified.WPT system is mainly composed of three parts:PFC converter is used to achieve power factor correction, reduce the harmonic of input current and decrease the pollution to the grid; wireless power transfer institution is composed of a DC-DC control circuit, a full-bridge inverter, S-S circuit and synchronous rectifier circuit, and it can achieve power wireless transfer; charging control circuit can complete charging control.In this article, the WPT system for EV can charge four SP12-50lead-acid batteries stably. The output power is500W, the efficiency of system is82.5%, the distance of power transfer is15cm and the diameter of coils is46cm. |
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