基于频率调节的电动汽车无线充电互操作性提升方法研究

Research on Improving Interoperability of Electric Vehicle Wireless Power Transfer Based on Frequency Adjustment

随着电动汽车无线充电技术的普及,如何实现不同厂家、不同型号的地面端与车辆端设备之间的互联互通,已成为制约无线充电技术推广和规模化的关键性问题。该文首先通过定义归一化角频率和电路类品质因数Q、Qf表征系统频率与系统固有参数特性,提出一种电动汽车无线充电系统模型的简化方法,并对系统频率特性进行分析研究;然后提出基于频率调节提升电动汽车无线充电系统互操作性的方法;最后搭建大功率电动汽车无线充电互操作性实验平台,通过仿真与实验验证了通过频率调节提升互操作性的正确性。该文对电动汽车无线充电技术的推广与产业化发展提供了理论支撑与技术参考。

In recent years,electric vehicle wireless power transfer technology has been popularized and promoted due to its advantages of high safety,high reliability,high energy efficiency and high adaptability.However,with the development of the technology,it will inevitably lead to the coexistence of multiple manufacturers,models and technical routes.There are obvious differences in power level,transmission distance,coil type,compensation structure,control mode,packaging process,communication and other aspects.Therefore how to realize the interoperability between ground terminal equipments and vehicle terminal equipment which comes from different manufacturers and models has become the key to the development of electric vehicle wireless wireless power transfer technology.This paper proposes a method to improve system interoperability based on frequency regulation.And according to this method the output characteristics of systems without interoperability or with poor interoperability can be improved in a wide range.Firstly,the fundamental wave analysis method is used to construct the KVL equation for the wireless power transfer system of LCC-LCC type electric vehicle.By defining the normalized angular frequency,the circuit similar quality factor Q and Qf to characterize the system frequency and the inherent parameter characteristics and simplify the equation of the system.Then simplify the expressions of the system output power and system efficiency by using the relationship of the order of magnitude under.According to the above study,the change curves of the output power and system efficiency under different system parameters are determined.The above analysis proves theoretically the influence of system frequency on interoperability.A method to improve the interoperability of the wireless power transfer system based on frequency regulation is proposed.US,IS,UL,IL is the power supply voltage,power supply current,load voltage and load current respectively.First,determine the optimal resonance point of the system through simulation and record the system frequency at this point as f0.The experiment starts from f0,at the same time,determine the maximum values Poutmax andηmax of Pout andη,and the maximum allowable error rangesεP andεηof Pout andηaccording to the simulation.Then the system frequency was adjusted.During the experiment,the US,IS,UL,IL in the circuit was measured and calculate Pout andη.Select the frequency change step asΔf(Δf>0).Set the system frequency to f0+nΔf(n=0,1,2,…)and it is called forward frequency modulation.Record|Poutmax-Pout|=εPn and|ηmax-η|=εηn,and judge the relationship betweenεPn andεP,εηn andεη.If the value satisfiedεPn≤εP andεηn≤εη,then the system has met the interoperability requirements.If not,continue to stack the steps.When the frequency changes to the critical point of the specified frequency range,if interoperability has not been achieved,reverse frequency modulation will be carried out like forward adjustment.The experimental results show that the output power and transmission efficiency of the system will change with the change of system frequency and the interoperability of the system will change according to the frequency too.This provides the feasibility of improving system interoperability through frequency regulation.However,compared with the simulation results,the experimental results are relatively low and the resonance points are shifted to the right by 0.25~0.5 kHz.The main reasons are environmental interference,device loss,statistical error,etc.