| Safe,reliable and convenient power transmission has always been the pursuit goal of humanity.Magnetic coupling resonant wireless power transmission technology has a meter-scale transmission distance and higher efficiency,providing a new power transfer scheme for humans.Because this technology solves the problems of leakage,electric spark and aging of electrical connectors caused by traditional wired power transmission,it has many advantages in applications such as electric vehicle,mobile phone,biomedical equipment and other fields.At present,products based on this technology have also appeared on the domestic and foreign market.According to the research background of electric vehicle charging,this thesis builds a miniaturized wireless charging platform,Based on the principle of magnetically coupled resonant wireless power transmission.By analyzing the charging characteristics of electric vehicle,a frequency conversion control strategy suitable for electric vehicle is proposed,which makes the system have higher transmission efficiency and practical application ability.Firstly,based on the principle of resonance and the equivalent circuit theory,a mathematical model of series-series resonant wireless power transmission is established.The relationship among load,compensation capacitance,coupling coefficient and system efficiency,phase angle of total impedance,output voltage and output power are given.The principle of frequency splitting in strong coupling is analyzed,and the simulation model based on MATLAB is built.Secondly,according to the overall design requirements of the wireless charging system.A hardware circuit topology was designed,including the design electromagnetic coupling mechanism,compensation capacitance selection,circuit board design and wireless communication programme.According to the battery charging characteristic curve of the electric vehicle,two DSP controller were used to the system control strategy design,and related program writing.Finally,we completed the experiment platform construction and program debugged work,and carried out the experiment of wireless power transmission under different distance.Based on the condition of 7cm spacing and 150 V input voltage,a constant voltage 150 V wireless charging simulate experiment was conducted after constant current 3A through the adjustable load,The maximum output power was 450 W,the highest efficiency was about 90.6%,and the average efficiency was about 89.6%. |
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