Characteristic and Thermal Analysis of Permanent Magnet Eddy Current Brake

In this paper,the subdomain analysis model of the eddy current brake(ECB)is established.By comparing with the finite element method,the accuracies of the subdomain model and the finite element model are verified.Furthermore,the resistance characteristics of radial,axial,andHalbach arrays under impact load are calculated and compared.The axial array has a large braking force coefficient but low critical velocity.The radial array has a low braking force coefficient but high critical velocity.The Halbach array has the advantages of the first two arrays.Not only the braking force coefficient is large,but also the critical speed is high.The parameter analysis of the Halbach array is further carried out.The inner tube thickness and air gap length are the sensitive factors of resistance characteristics.The demagnetization effect is significantly enhanced by the increase of the inner tube thickness.In order to ensure that the ECB does not overheat,the electromagnetic-thermal coupling model is established based on the heat transfer theory.The temperature rise of the inner tube is obvious while that of the permanentmagnet is small.The temperature rise of the inner tube is more than 20 K each time,and that of the permanent magnet is less than 1 K each time.

Electromagnetic buffer optimization based on Nash game

Aiming at the problem of unstable buffering process of electromagnetic buffer(EMB)under intensive impact load,a three-segment electromagnetic buffer is proposed.The inner tube and air-gap of EMB are divided into three segments.The finite element analysis and impact test results show that the resultant resistance force(RRF)curve has two hump-shaped peaks,which is the reason for the unstable buffering process.In order to stabilize the buffering process,a multi-objective optimization design method of EMB based on Nash game theory is proposed.Firstly,the optimization model is established by taking the two peaks of the RRF curve and the maximum buffer displacement as the optimization objectives.Secondly,the multi-objective optimization model is transformed into a game model by sensitivity analysis and fuzzy clustering.Then,a Nash equilibrium solution strategy of EMB Nash game model based on symmetric elitist information exchange is proposed,which integrates gene expression programming(GEP)surrogate model and genetic algorithm(GA)as an optimization solver.Finally,the Nash equilibrium of the game model is obtained.The results show that the smoothness of the RRF curve has been significantly improved,which proves the effectiveness of the game strategy.