基于磁心与线圈参数优化的非侵入式磁场取能系统功率密度提升方法

Power Density Improvement Method of Non-Invasive Magnetic Field Energy Harvester System Based on Optimization of Magnetic Core and Coil Parameters

非侵入式磁场取能系统具有结构简单、供电稳定等优点,是解决变电站母排环境中状态监测传感器电池供电寿命有限的有效手段,但因功率密度较低制约了其应用。对于非侵入式磁场取能系统,磁心与线圈参数对其功率密度的影响非常显著。然而,现有方法对磁心与线圈参数的分析相对独立,优化磁心时仅以互感为指标,忽略了该过程线圈参数变化对功率密度的影响。对此,该文考虑磁心尺寸对线圈参数的影响,以功率密度为指标,详细分析线圈匝数、线圈线径、磁柱侧面边长与叠片厚度对系统功率密度的影响。并在此基础上,提出一种优化磁心与线圈参数的功率密度提升方法,即设计线圈匝数、线圈线径、磁柱侧面边长与叠片厚度的最优值,以获取更高的功率密度。最后,基于所提出的方法制作了系统样机并进行测试。实验结果表明,对于限定磁心尺寸为30 mm×30 mm×40 mm的系统,在100 A母排电流下,系统经磁心与线圈优化后功率密度可达4.18 mW/cm~3,提升至系统优化前功率密度的35倍,验证了所提出方法提升功率密度的有效性。

The wireless sensor is an effective method to monitor the status of the substation busbar.The traditional power supply source of sensors is the battery.However,the battery has limited life and needs to be replaced frequently,which challenges the long-term stable operation of the sensor.The non-invasive magnetic field energy harvester system has the advantages of a simple structure,stable power supply,and convenient installation,which can effectively solve the power supply problem of the sensor.Since the core structure of the non-invasive magnetic field energy harvester system is non-closed,the power density of the system is low.In addition,the application of the non-invasive magnetic field energy harvester is seriously restricted.For the non-invasive magnetic field energy harvester system,the influence of core and coil parameters on its power density is very significant.Especially in the application scenario where the space is limited,the system power density cannot be improved by increasing the volume of the magnetic core.Hence,optimizing the magnetic core and coil parameters is particularly critical in this scenario.Unfortunately,the existing system optimization methods for analyzing magnetic core and coil parameters are relatively independent.Only mutual inductance is taken as the optimization index when optimizing the magnetic core,so the influence of coil parameter changes on the power density is ignored,which cannot accurately guide the design of the system prototype.Considering the influence of magnetic core size on coil parameters and taking power density instead of mutual inductance as an optimization index,this paper proposed a power density improvement method to optimize magnetic core and coil parameters.Firstly,the equivalent circuit of the system was analyzed,and the power density expression was established.Then,the optimization direction was clarified to improve the induced voltage,reduce the coil resistance,and reduce the magnetic core volume.Secondly,the H-shaped structure magnetic core was proposed to effectively gather the magnetic flux and reduce the coil resistance.Then,the induced voltage,the coil resistance,and the magnetic core volume were represented by magnetic core and coil parameters,and the influencing factors of the power density were determined.Thirdly,the influences of coil turns,coil diameter,lamination thickness,and magnetic column side length on the system power density were analyzed based on the finite element simulation.A power density improvement method was proposed by optimizing the magnetic core and coil parameters,i.e.,designing the optimal values of coil turns,coil diameter,laminate thickness,and magnetic column side length to obtain higher power density.Finally,the energy harvester with different core and coil parameters was fabricated,and their output performance was tested.The experimental test results show that for the energy harvester with a limited core size of 30 mm×30 mm×40 mm,under the condition of 100 A busbar current,the load voltage of the energy harvester is 3.64 V after optimization,which meets the power supply demand of most sensors.Moreover,the power density can reach 4.18 mW/cm3,35 times the power density before optimization,verifying the effectiveness of the proposed power density improvement method.