The Theoretical And Experimental Study On Displacement Eddy Current Sensor With Double Coils

Eddy current sensor has many advantages.for example,it has simple structure,quickly responding speed,and the ability of resisting interference.It is widely used in engineering projects about large machinery state detection.So its performance is directly related to the safe operation of the whole unit.The paper designed the eddy current sensor with double coils according to the basic principle of eddy current sensor.The sensor has high accuracy,large linear measuring range.Firstly,based on the basic principle of eddy current sensor,the paper analyzed the working principle of eddy current sensor with double-coil according the basic principle of eddy current sensor,and then,established the mathematical model of the sensor based on the simplified method,worte a matlab program based on the model which is used for calculating the relationship between the voltage of detecting coil and displacement.It laid the foundation for optimization design of the sensor coil.Secondly,the paper discussed the geometry size of the sensor coil effect on the performance of the sensor in the aspect of theory.In the process of the optimization design,determined measuring range as objective function,selected the key parameters in many parameters about the coil,got the coil parameters after optimization according to the optimization program,analysised and compared the sensor performance changes before and after the optimization according to the experiment.The mearsuring range is impoved by 7mm,the nonlinear error is reduced by 39.7%after optimization.Finally part is designing the circuit which the sensor needs.Accoriding to different functions,the circuit can devide to two parts.First part is signal generator which used AFG3021C arbitrary function generator.It can generate the sine wave we need.Second part is signal processing circuit,it contains signal amplifier,filter and nonlinear compensation circuit.Used Multisim 12 to debug and simulate the circuit,did the simulation experiment and got the output curve of the sensor.The linear range is 18mm.the sensitivity is 0.5v/mm after calculation-Compared to the ?25mm sensor produced by Bentley company which is used by power plants,its linear range is increased by 5.5mm.