Research Of Wireless Charging Key Technologies For Electric Vehicles

Electric vehicle wireless charging technology as an emerging technology, it is receiving increasing attention。Compared with the traditional way of charging, wireless charging technology is more convenient, not affected by the climate and the environment, no electric shock risk. The main contents of this thesis is focus on the key technologies of wireless charging system, and build a complete set of 500W electric vehicle wireless charging system.Firstly, this thesis described the research status of wireless charging technology, and carry out a detailed analysis of the typical structure of the electric vehicle wireless charging system. This structure has been used as design guidelines of the electric vehicle wireless charging system.Secondly, the preceding stage of the wireless power transfer system is designed, including the interleaved power factor correction (PFC) circuit and BUCK circuit for power control. The job of the circuit parameter design, control method design and simulate the circuit was finished. The coil pads of wireless power transfer and compensating network was researched. All kinds of compensating network was introduced. And the series-series (SS) compensation network is applied to the system. On the basis of compensating network, using the thought of adjustment parameters, the soft switch of inverter was designed, and the effectiveness of soft switch was verified by simulation. Wireless charging coil pads were designed to three layer structure, including coil, ferrite and shielding layer. Using transmission efficiency and the coupling coefficient as the optimization goal to optimize coil pads design. Transmission loss analysis is used to further optimize the design of the ferrite layer.Lastly, on the basis of work before, the design work of system’s hardware and software was completed, and a wireless charging prototype was built. The test work was start from part to whole system. The power factor correction circuit, the BUCK circuit and the synchronous rectification circuit was tested respectively. Then the whole system was tested under two different conditions. The first one was well aligned, and the power was 500W. The test result was that the maximum transmission efficiency from the grid to the load is 90.26%, and the power factor of the circuit is 0.997. The other one has a 15cm misalignment, and the power is 400W. The maximum transmission efficiency from the grid to the load is 89.566%, and the power factor of the circuit is 0.998...