Optimal Design Of Eddy Current Displacement Sensor In A Magnetically Levitated Artificial Heart

The eddy current displacement sensor coil in a magnetically levitated artificial heart should penetrate two layers of titanium alloy shell to measure the conductor displacement whose scale is close to the coil, which is different from the ordinary eddy current sensor measuring the metal displacement. In order to design a eddy current displacement sensor to detect the rotor displacement in a magnetically levitated artificial heart, this paper analyzed the working principle of eddy current sensor in the artificial heart, and designed the appropriate sensor detection circuit. Furthermore, the influence of titanium alloy shells on the characteristics of sensor coils was investigated and the performance of the sensor coil under different frequency of excitation signal was studied, and the coil geometry was optimized.To sum up, the following works are carried out:1. Analysis of working principle and design of detection circuit of the eddy current displacement sensor in the artificial heart.According to the working principle of the eddy current displacement sensor, the working mechanism of the eddy current displacement sensor in the artificial heart was studied, the sensor’s equivalent model was established, and the main factors which affected the sensor performance were analyzed. According to the structure of the artificial heart, the sensor detection circuit was designed, and the parameter value of the components of the circuit was optimized, which can make the sensor detection circuit have the best sensitivity.2. Research on the characteristics of the eddy current sensor coil which penetrates the metal shell to detect conductor displacementThe distribution characteristic of the eddy current was analyzed by the finite element simulation analysis software. The experimental test platform was designed, the influence of titanium alloy shells on the characteristic of sensor coils was studied through the experiment. And the performance of the sensor coil under different frequency of excitation signal was investigated.3. The influence of the coil size on the sensor performance was studied when the target size is close to sensor coils.The performance of different size of coils in the artificial heart was tested by the experiment. The influence of the coil size to the sensor performance was studied when the target size is close to sensor coils. The coil size was optimized, and the actual sensor performance was tested.The researches above analyzed the working principle of the eddy current sensor which penetrates the metal shell to detect the conductor displacement, the distribution characteristics of the eddy current was mastered, the coil features was obtained, which can provide reference for design of the eddy current displacement sensor that penetrates the metal shell to detect the target’s displacement. The actual sensor’s performance can meet the expectations and requirements.