Research On Structural Strength Of Large-mass And Long-stroke Thomson Coil Actuator

Compared with the traditional actuators for circuit breakers,Thomson coil actuators(TCAs)have the advantages of short delay time,fast motion and simple structure.TCA can drive the contacts to reach the rated travel in a few milliseconds,which satisfies the requirements of high voltage DC circuit breaker for fast operating mechanism.With the increase of voltage level,researchers focus on the mechanical life,the mechanism of structural damage under high-speed conditions,and the stability and reliability of TCA.In this paper,the coil-disk TCA is taken as the research object.Based on the COMSOL Multiphysics and material mechanical properties test,a 2D finite element(FE)transient axisymmetric model coupled with magnetic fields,solid mechanics and electric circuits is implemented.According to the force and movement characteristics of TCA,the working process is divided into three stages: driving stage,inertial stage and buffer stage.The differences of motion characteristics between the rigid model and flexible model are analyzed.The force characteristics and stress distribution of key components,such as armature,transition joint and transmission rod,are discussed,and the location of weak mechanical strength is identified.For the drive stage,based on the modal analysis,the influence of structure parameters on the natural frequency of TCA is discussed,and the relationship between the natural frequency and the transient response of TCA is determined.A new armature with three characteristic parameters is proposed,and their influence on the structural strength and driving characteristics is further discussed.The effects of Lorenz force density,electromagnetic force waveform on stress distribution are discussed,and the feasibility of dual-pulse drive technology in improving structure strength is also analyzed.For the buffer stage,the stress distribution of TCA with different buffers is analyzed.The results show that the hydraulic and electromagnetic buffers are suitable for the operating conditions.Finally,a 110 k V ultrafast mechanical switch prototype is developed and tested to verify the accuracy of the simulation model and the effectiveness of the optimization method.