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利用谐振式磁传感器的电流传感技术及器件系统研究
【作者】 李辉；
【导师】 卞雷祥；
【作者基本信息】 南京理工大学 ， 精密仪器及机械， 2021， 硕士
【摘要】 电流传感技术在电力系统中的在线监测、继电保护、电力检修、智能设备控制等领域均发挥着极为重要的作用。随着智能电网的快速发展以及电子设备健康监测概念的提出,急需通过先进的传感和测量技术为其控制决策提供信息支撑。本文采用磁致伸缩材料与音叉谐振器复合结构的谐振式磁传感器,设计了谐振式电流传感器,具有体积小、功耗低、灵敏度高等优点,且可以用于交直流电流的测量。通过理论分析、有限元仿真和实验测试对所设计的谐振式电流传感器进行了研究,主要工作有:介绍了谐振式磁传感器的原理及组成,描述了磁敏感单元的制备过程并对传感器性能进行了测试,介绍了传感器检测电路的设计,电路仿真结合公式推导分析了其工作原理,对常用的频率信号检测方法进行了介绍,测试了测频芯片的性能。分析了单敏感单元谐振式磁传感器用于电流测量的工作原理,制备了传感器并搭建了实验系统,对传感器的灵敏度和分辨率进行了测量,0-10A直流测量时灵敏度和分辨率为0.9Hz/A和0.1A,0-70A交流测量时灵敏度和分辨率为0.704Hz/A和1A,但其性能受温度影响较大。在此基础上设计了差分谐振式电流传感器,针对非接入式测量与接入式测量两种方案,建立了传感器输出频率与输入电流的数学物理模型,结合有限元仿真对电流测量的工作原理进行了分析。制备了差分谐振式电流传感器,搭建了实验系统对传感器的性能进行了测试。0-10A直流实验时,单根导线非接入式测量灵敏度和分辨率为1.36Hz/A和30m A;螺旋线圈接入式测量灵敏度和分辨率为25.2Hz/A和5m A。交流实验时单根导线非接入式测量灵敏度和分辨率为1.05Hz/A(0-70A)和1A;螺旋线圈接入式测量灵敏度和分辨率为13.7Hz/A(0-20A)和0.1A。还进行了温度特性测试,结果表明差分传感器的非线性温度系数比单传感器小了一个数量级,能有效地抑制温漂。针对动态信号测量,利用F/V转换电路的快速响应特性,对电流测量展开了研究,分析了F/V转换电路的工作原理,搭建了实验测试系统对差分谐振式电流传感器的交直流特性进行了测试,结果表明直流测量时0-10A范围灵敏度为2.81m V/A,0-200A范围灵敏度为1.7m V/A;交流测量时采样曲线能很好的还原动态信号,且0-70A范围灵敏度为0.0934m V/A,0-150A范围灵敏度为0.0493m V/A。
【Abstract】 Current sensing technology plays a very important role in the field of online monitoring,relay protection,power maintenance and intelligent equipment control in power system.With the expansion of power grid scale and concept of electronic equipment health monitoring,it is urgent to provide information support for its control decision through advanced sensing and measurement technology.In this paper,a resonant magnetic sensor based on the composite structure of magnetostrictive material and tuning fork resonator is used to design a resonant current sensor,which has the advantages of small volume,low power consumption and high sensitivity,and can be used for dc and ac current measurement.The resonant current sensor is studied through theoretical analysis,finite element simulation and experimental test.Its main work is as follows:The principle and composition of resonant magnetic sensor are introduced.The preparation of magnetic sensitive cell is described and the performance of the sensor is tested.The paper also introduces the design of the sensor detection circuit.Circuit simulation is combined with formula derivation to analyse its working principle.The commonly used frequency signal detection methods are introduced and the performance of the frequency measurement chip is tested.What’s more,working principle of current measurement with single unit resonant magnetic sensor is analysed.We prepared the sensors and set up the experimental system to measure the sensitivity and resolution of the sensor.The result shows that 0-10 A dc measurement sensitivity and resolution are 0.9 Hz/A and 0.1 A,0-70 A ac measurement sensitivity and resolution are 0.704 Hz/A and 1 A.we also tested the temperature characteristics of the sensor and its performance is greatly affected by temperature.On this basis,the differential resonant current sensor is designed for non-access and access current measurement schemes.A mathematical model of the output frequency and input current of the sensor is established through formula derivation for the two current measurement schemes.Based on the finite element simulation,the working principle of current measurement is analyzed.The differential resonant current sensor is prepared,and the experimental system was built to test the performance of the sensor.For 0-10 A dc measurement,the sensitivity and resolution of the single conductor are 1.36Hz/A and 30 m A respectively.The measurement sensitivity and resolution of the spiral coil are25.2Hz/A and 5m A.During the ac measurement,the sensitivity and the resolution of the nonaccess type is 1.05Hz/A(0-70A)and 1A.The sensitivity and the resolution of access type measurement is 13.7Hz/A(0-20A)and 0.1A.The result of temperature experiment shows that the nonlinear temperature coefficient of differential sensor is one order of magnitude smaller than that of single sensor,and the temperature drift is effectively inhibited.For dynamic signal measurement,the current measurement is studied by using the fast response characteristic of F/V conversion circuit.The working principle of F-V converter circuit is analyzed.An experimental testing system was built to test the ac/dc characteristics of the differential resonant current sensor.The results showed that the sensitivity of the dc sensor is2.81 m V/A in the range of 0-10 A and 1.7m V/A in the range of 0-200 A.During the ac measurement,the sensitivity in the 0-70 A range was 0.0934 m V/A,and in the 0-150 A range was0.0493 m V/A.