Development Of High Frequency Power Supply For Wireless Charging Electric Vehicles

Electric vehicle is a type of vehicle which uses electric energy as the source to drive an electric motor.Compared with gasoline and diesel vehicles,electric vehicles have some advantages: no emissions,no pollution,low noise,and easy maintenance.They have been widely used in recent years.As the key equipment for charging electric vehicles,the charging cable of the wired charging pile is inconvenient to use during the charging process,which brings frequent plugging and unplugging of the plug,generating electric spark at the interface,bringing about discharging phenomenonservice life.It can jeopardize the charging safety as well as the service life of battery.Wireless charging method eliminates the charging cable and effectively avoids the problems caused by wired charging.As an important part of the wireless charging system,the wireless charging high frequency power supply plays a key role in the power transmission.The high frequency power supply uses the analog circuit to control and adjust the output trigger pulse.However,the control of the high-frequency power supply through the analog circuit has the disadvantages of unstable operation,inaccurate output adjustment,and no protection function.Using the digital signal processor DSP to control the power supply can effectively control the output voltage and output frequency of the high-frequency power supply,and can monitor the working state.When the output voltage or current of the power supply exceeds the protecting limit,the protection mechanism operates to turn off the trigger pulse,thereby avoiding overvoltage and overcurrent generated during operation,and effectively improving the stability and reliability of the power supply operation.In this paper,the research and design of DSP controlled high frequency power supply is carried out.Firstly,the working principle of the high-frequency power supply is analyzed.According to the output index and input requirements of the power supply,the overall design scheme of the high-frequency power supply is carried.Main circuit structure of the power supply and the control mode of the inverter circuit are designed.The influence of the impedance transformation network on the output characteristics of the power system is analyzed,and the effect of the transformation network is verified by simulation.Based on the establishment of the power control model,the adaptive control method of the variable inductance parameter reference model is proposed.The effectiveness of the model adaptive control method is verified by comparing with the simulation results of the traditional PI control method.Secondly,the main circuit,control system,sampling and conditioning circuit of the power supply system are designed,and the high frequency inverter PCB circuit board is designed and built.Based on the hardware design,the software control main program,trigger pulse generation program,soft start and sampling protection program of the power supply are designed.The debugging of the program was carried out on the CCS development platform.Finally,based on the construction of the power system experimental platform,the output voltage signal of the drive circuit is tested.The output voltage and current of the high-frequency power supply is tested under the condition that the input side is connected with the 380 V three-phase power frequency voltage and the output side is connected to the wireless transmission coil.The current is observed and the proposed variable-inductance reference model fuzzy adaptive control method is experimentally verified.The experimental results show that frequency,output voltage and output power of the developed high-frequency power supply can be adjusted.Output frequency and voltage can be changed according to the actual condition of the coil with certain theoretical and practical value.Compared with PI control method,the proposed reference model fuzzy adaptive control method has a smaller overshoot and shorter adjustment time under the same load variation,and has better control stability.