Research On Optimization Method Of Excitation Magnetic Circuit Of High Performance Electromagnetic Flow Sensor

Electromagnetic flow sensors are widely used in the field of flow measurement because of their simple structure,high measurement accuracy,fast response speed,and no pressure loss.The excitation magnetic circuit structure of electromagnetic flow sensor determines the sensor's induction magnetic field distribution,which not only directly affects the sensor's measurement performance,but also affects its system power consumption.However,there are many structural parameters of the excitation magnetic circuit,so it is difficult to optimize the magnetic circuit structure of electromagnetic flow sensor according to different practical performance requirements.Therefore,this dissertation combines theoretical analysis,finite element simulation,response surface method modeling and genetic algorithm optimization,to establish a complete and efficient magnetic circuit structure optimization design method,which can improve overall measurement performance of the sensor under the premise of the system power consumption unchanged.The work in this dissertation is mainly divided into the following aspects:Firstly,study the individual changes of magnetic circuit structure parameters' influence on sensor performance.Use COMSOL software to establish the finite element simulation model of electromagnetic flow sensor,and determine the effective working area of the sensor's magnetic field.Analyze the change law of the performance evaluation indexes(induced electromotive force,dynamic response time constant,average magnetic induction intensity,magnetic field's uniformity)when magnetic circuit structure parameters(coil,yoke,pole shoe)are changed individually.Secondly,establish the response surface function models of the sensor with multiple parameters and multiple targets.Taking induced electromotive force,dynamic response time constant,average magnetic induction intensity,and magnetic field's uniformity as optimization goals,taking coil thickness,yoke width,pole shoe width and pole shoe length as design variables,the test plan is designed by central composite design method.The test plan is simulated and solved,and the response value of each optimization target is obtained,so as to establish the response surface function model of each optimization target and design variables.Thirdly,carry out multi-objective optimization of magnetic circuit structure parameters.The genetic algorithm based on satisfaction function is used to optimize the response surface function models of multiple objectives.When the dynamic response time constant is constrained to 5ms,the optimal magnetic circuit structure parameters with the strongest induced electromotive force and average magnetic induction intensity,and the most uniform magnetic field are obtained.Through finite element simulation,the performance parameters of original prototype and optimized prototype are analyzed and compared.Results show that,compared with the original prototype,induced electromotive force of the optimized prototype has increased by 29.58%,average magnetic induction intensity has increased by 15.72%,magnetic field's uniformity has increased by 13.29%,and dynamic response time constant is approximately equal to 5ms,which satisfies the constraints.The results verify the feasibility of the magnetic circuit structure parameters' optimization design method.Finally,the optimized sensor prototypes are developed and verified by experiments.According to the optimized magnetic circuit structure parameters,three optimized prototypes are trial-produced.Electrical parameter experiments,magnetic field measurement experiments,and water flow calibration experiments are carried out on the original prototype and optimized prototypes.The experimental results show that,the system power consumption of the sensor remains basically unchanged after optimization.The water flow calibration measurement error of the three optimized prototypes is less than ±0.5%,and the repeatability error is less than 0.14%,which meets the accuracy requirement of 0.5 level.The overall measurement performance of optimized prototypes are better than the original prototype,which verifies the correctness and feasibility of the optimization design method of the magnetic circuit structure parameters proposed in this dissertation.