Simulation Optimization And Design Of Eddy Current Displacement Sensor Based On Inductance Change Rate

With the development of aerospace technology,precision instrument manufacturing technology,medical technology,semiconductor industry and many other fields,the demand for the sensitivity and stability of displacement sensor is higher and higher.Eddy current displacement sensor is widely used in harsh and changeable environment and special application occasions because of its advantages of non-contact,portability,easy operation,wide frequency response and high precision.As the core component,the size,turns,thickness and excitation frequency of the probe coil will directly affect the sensitivity and detection range of the sensor.Therefore,it is very important to comprehensively consider the parameters of the coil to obtain the eddy current displacement sensor with large detection range and high sensitivity.In this paper,through the systematic analysis of the influence of each parameter of the eddy current displacement sensor on its performance,two equivalent models are established and compared.Through the finite element simulation technology,the performance parameters of the eddy current displacement sensor are completely obtained.A new method is proposed to determine the optimal parameters by calculating the inductance change rate of displacement between 0.1 and 0.2 mm.The temperature change is simulated in the simulation software.Under the condition of temperature change simulation,the excitation frequency and impedance are simulated to obtain the optimal excitation frequency to suppress the temperature drift.The design of the backend measurement circuit is simplified,the inductance change rate and measurement resolution are increased,and the linearity and fitting error are reduced.The main work of this paper is as follows:(1)Combined with the transformer model and equivalent loop model analysis,the inductance displacement characteristics of the sensor were obtained,and the theoretical formulas of the probe coil inductance,quality factor,and a series of eddy current displacement sensor responses were derived.The influence of operating frequency and temperature on the performance of the sensor.The parameter design of the probe coil was analyzed and optimized.The basic principles and ideal range of the optimal design of the probe coil were summarized.(2)Based on the simulation software COMSOL Multiphysics,the eddy current displacement sensor is modeled.Through the electromagnetic field simulation of the model,the model is comprehensively analyzed and reasonably optimized.In the range of large inductance value,the maximum change rate of inductance is obtained when the displacement is 0.1 ? 0.2mm,and the amplitude of the displacement-inductance change curve is the largest,which can be fitted more accurately and optimize the parameters.The simulation software is used to simulate the temperature,and the optimal excitation frequency is obtained when the change rate of the inductance with the temperature is the smallest.(3)According to the optimal parameters of the simulation,the sensor coil is manufactured,and the LDC1000 EVM resonant frequency measuring circuit is selected to realize the complete design of the eddy current displacement sensor system.The optimal range of the sensor is 800 ? m when the resolution is in the micron level,100 ? m when the resolution is in the submicron level,the linearity is 0.67%,and the fitting error is 0.05%.