Research On Mechanical Electric Magnetic Thermal Coupled-field Modeling And Dynamic Characteristic Optimization Of Ac Contactor

The quality of dynamic characteristics is one of the most important factorsaffecting the performance and electrical life of a contactor. Dynamic process is acomplex process interacted by electric field, magnetic field, mechanical movementand temperature field. The traditional dynamic analysis methods only considerdynamic characteristics coupled by electric field, magnetic field and mechanicalmovement, ignoring the temperature effect. However, the difference between hightemperature life and normal temperature life indicates the importance of thetemperature effect on dynamic characteristics. In this paper, a multi-field couplingmodel of contactor coupled by electric field, magnetic field, mechanical movementand temperature field is built dealing with a specific AC contactor, electromagneticcharacteristics are calculated and tests are done to demonstrate the effectiveness ofthe model. Based on the new tested model, the effect of temperature on dynamiccharacteristics is analyzed and two optimizing design methods are proposed, inorder to improve the performance of the contactor.Firstly, in this paper, a multi-field coupling model of contactor coupled byelectric field, magnetic field, mechanical movement and temperature field is built.By analyzing the structure and performance parameters of the contactor, magneticcircuit model, electric circuit model, mechanical movement model and temperaturefield model are built respectively. Furthermore, analysis of the relationship betweentemperature-sensitive parameters and temperature, including coil parameters,magnetic properties of the permanent magnet and mechanical properties of elasticelements is done and the mechanism of temperature affecting the parameters isgiven, aiming to realize the new coupling model.Secondly, dynamic and static characteristics have been calculated. The reactionforce and static attraction force are calculated by finite element analysis to thismodel and the model is checked by the obtained pull-in and release voltages,preliminarily. Then the dynamic characteristics are calculated after loading thereaction force curve to this model, to demonstrate the correctness of the model bytesting the time parameter.Thirdly, the effect of temperature on dynamic characteristics is analyzed basedon the model. After calculating the steady temperature rise of the contactor, thetemperature-rise ranges of key components are achieved and the effect oftemperature-sensitive parameter’s variation on the reaction force or attraction forceare analyzed respectively. The time parameter and pull-in voltage obtained by the test demonstrate the relationship between dynamic characteristics and temperature.Finally, two optimizing methods are proposed. Temperature-rise optimizingmethod uses silicon steel sheet iron core, in order to reduce the heat of theelectromagnetic system. After optimizing electromagnetic system and contactsystem, the loss of electromagnetic system is reduced and the speed of pulling andreleasing is increased. Structure-size optimizing method aims to increase thecapacity of breaking arc, by increasing the opening travel of the contact. Based onthe redesign and simulated calculation of the attractive force and the reaction force,the opening travel of the contact and the breaking speed will increase. Theoptimizing results of dynamic characteristics show that the contactor life will beimproved. Structure-size optimizing method increases the AC contactor’s life to alarge extent by demonstrating test.