Nonlinear PM Degradation Model And Its Application In Defferential Magnetic System

For a differential magnetic system with permanent magnets(PMs),PMs can be described as the core components of the entire electromagnetic system.Its performance changes will have a huge impact on the overall performance of the differential magnetic system.Modeling the degradation trend of PMs,and then deriving the overall performance change trend of the electromagnetic system,and based on this,optimizing the design of the differential magnetic system in the relay,will greatly help to extend the life of the relay.Firstly,this article uses the usual finite element simulation method to simulate the static suction characteristics of the electromagnetic system,compares the simulation results with the measured results.Then,based on the aforementioned experimental measurement data,Arrhenius model and logarithmic function model were selected to model the degradation of permanent magnetic performance.At the same time,the PM parts in the model are processed in sections based on the actual charging and demagnetization simulation.Based on the hysteresis model,the material properties of the PMs in the model are reset.Secondly,the degradation mechanism of the PM was analyzed,the demagnetization rate based on the surface magnetic strength was determined as the characteristic parameter of the PM performance,the degradation test of the PM at different temperatures was conducted,and the overall degradation trend of the PM performance was studied.Then,based on the aforementioned experimental measurement data,the Arrhenius model and the logarithmic function model were selected to model the degradation of the PM performance.By comparing the modeling results,the logarithmic function model can better reflect the overall trend of PM performance degradation,so the logarithmic function is finally selected to model the PM degradation.Then,through a single factor simulation,the key size parameters that have a greater impact on the static electromagnetic characteristics under PM degradation are determined.Based on the self-defined model,establish a fast calculation model that takes voltage,rotation angle,PM remanence,and size parameters as input,and static suction torque as output.Using the Kriging model for error fitting,combined with the permanent magnet magnetic performance degradation model,you can obtain a rapid calculation model of the static suction moment of the differential magnetic system after a period of degradation at a certain temperature.This laid the foundation for subsequent optimization.Finally,based on the established PM degradation model and the rapid calculation model of the static electromagnetic torque of the differential magnetic system,taking the static electromagnetic torque of the release position when the PM degenerates the differential magnetic system without excitation and under the pull-in voltage as the optimization objective function,At the same time,considering the tolerances generated during production and processing,the size parameters of the differential magnetic system are optimized.Finally,the finite element simulation is used to verify whether the technical indicators are met before and after degradation,and the feasibility of the optimization scheme is verified.