| In recent years,with the further development and wide application of new energy technology,Wireless Power Transmission,as a new power transmission technology suitable for various occasions,whinch hsa received active attentio,research and aoolication from universities and science and technology companies.There are static power transmission technology and dynamic power transmission technology in WPT.The dynamic wireless power transmission technology is the main research direction,which has a brighter development prospect and better practicability than the static charging technology.However,due to the time-varying and uncertainty of dynamic wireless power transmission system and other environmental factors,the offset of the relative position of the coupling mechanism may occur during the charging process,resulting in the change of the resonant frequency,which affects the transmission efficiency and makes the system time-varying and uncertainty.This thesis studies the dynamic wireless power transmission system which can be used in electric vehicles.1.Based on the requirements of dynamic wireless power transmission system for electric vehicles,the appropriate resonant network and coupling structure are selected.For the selection of resonant compensation network,the transmission characteristics of wireless power transmission system based on SS model and other three models of resonant compensation network under different conditions are analyzed,such as different load resistance values and different coupling coefficients.For the selection of coupling mechanism,the effects of circular and rectangular coupling structures on the transmission efficiency of the system are analyzed respectively.The simulation results are analyzed,and SS resonant compensation network and rectangular coupling structure are selected.2.The whole dynamic wireless power transmission system is modeled,and the simulation model of the system is established by Matlab / Simulink software.The dynamic characteristics of the dynamic wireless power transmission system are analyzed.In the design of the system,the step-down module in the DC / DC module is used as the DC conversion link,and the value of the branch output voltage is controlled by the duty cycle of the switch.The energy from the input end to the output end in a cycle is controlled by the switch.3.When the frequency changes caused by the dynamic characteristics of the system lead to system detuning and efficiency decline,phase-locked loop technology is introduced.When the frequency changes occur,the system may have multiple resonant frequencies.When the traditional frequency tracking method is used,the optimal resonant frequency may not be guaranteed.Therefore,the phase-locked loop technology is used to track the frequency.The phase-locked loop can adjust the phase of voltage and current according to the obtained phase difference,so as to keep the output voltage and current in the same phase,and then obtain the optimal resonant frequency.The simulation circuit is designed by Matlab/ Simulink software,and the efficiency of the control strategy is verified.4.When the wireless power transmission system is used in the outdoor environment,the system will have more uncertainties and higher robustness requirements due to external factors.The linear active disturbance rejection controller technology is used,and the overall external influence is attributed to a linear change.The simulation circuit is designed by Matlab / Simulink software,and the efficiency of the control strategy is verified. |
PDF Full Text Request