Research On Parameter Optimization And Control Strategy Of EV Dual LCC Wireless Power Transfer System

Magnetically coupled resonant wireless power transfer(MCRWPT)technology has the advantages of long transmission distance,high efficiency and strong anti-migration ability.It is widely used in high-power scenarios such as wireless charging of electric vehicles.In this paper,the dual LCC electric vehicle MCRWPT system is studied,and the parameter migration model and power converter loss model are established as the basis.With the goal of improving the output characteristics,the design and optimization are carried out from the aspects of compensation network filtering characteristics,circuit parameters,magnetic coupling mechanism,bilateral cooperative control strategy,etc.To provide ideas for the design of system parameters with high migration resistance,the main work is as follows:This paper analyzes the high order dual LCC compensation network theoretically.Firstly,the corresponding output characteristics were obtained by establishing the reciprocal inductance equivalent models of S-S,LCC-S and dual LCC,and the dual LCC compensation network was selected to compare the applicability of the high-power charging system of electric vehicles.Secondly,the voltage interference ratio was defined to compare the filtering characteristics of each impedance loop of the dual LCC structure,and an improved LC-dual-LCC compensation network structure was proposed to further improve the filtering performance and reduce the input reactive power introduction.Thirdly,the frequency stability is compared and analyzed,the mathematical expression of total harmonic distortion and reactive power at the input end of the improved circuit network is established,and the design method of LC link is determined.Firstly,in order to compensate the errors existing in inductance and capacitance components of the network circuit in the actual wireless charging system,the parameter deviation was introduced into the circuit model,and the relationship between the deviation and the current amplitude,phase Angle and output characteristics of each branch was derived through the model.At the same time,the resistance deviation correction item was introduced to establish the expression of voltage stress and current stress of each device when considering the parameter deviation.Secondly,based on the principle of minimum change rate of power with parameter migration,considering the voltage stress and current stress of the device as well as the constraint conditions of input sensitivity when implementing ZVS,parameter design was carried out with primary and secondary side compensation inductance as the optimization object,and the circuit parameter optimization idea was obtained.Finally,the magnetic coupling mechanism was optimized by analyzing the influence of the area ratio and shape of the primary and secondary side coils on the displacement characteristics.Firstly,a dual phase-shifting control mode is adopted to maximize the output power for the system structure with symmetrical primary and secondary sides.A power converter loss model is established and substituted into the analysis of output characteristics to analyze the influence of phase shifting angles on power and efficiency when the voltage ratio changes and the relative displacement of the magnetic coupling mechanism occurs.Secondly,combined with the analysis of the relationship between phase shift Angle and output characteristics,the dual phase shift control strategy for MCRWPT system is designed to achieve high efficiency bilateral cooperative control.Finally,the rectifier phase shift Angle control mode based on BP neural network PID parameter adaptive is implemented to achieve stable output closed-loop control.An experimental platform was built to verify the rationality and validity of MCRWPT system analysis for electric vehicles.Firstly,the composition of the experimental platform is introduced,and the key parameters of the magnetic coupling mechanism and compensation circuit network are listed.Secondly,the filtering characteristics of the system compensation network are tested to prove that the new LC-dual-LCC compensation network has better filtering performance.Thirdly,the optimized design parameters are tested to verify the stability of the output under the change of system working conditions.Finally,the control experiment is carried out,and the schematic diagram of the driving board is introduced to verify that the system can realize the fast closed-loop response and the constant power control under the presence of disturbance.