Research On Iron Loss Analysis And Modeling Of Switched Reluctance Machine

Environmental Care and ecological civilization construction are one of the main contents of the 13 th Five-Year Plan.As the country pays more and more attention to energy saving and emission reduction,high-efficiency machines will become the focus and hotspot of the machine industry development.Switched reluctance machine(SRM)has the advantages of simple structure,solid body,wide speed range,high reliability,high efficiency and low cost,which will usher in a good development prospect.However,compared with permanent magnet machine,the power density and efficiency are slightly inferior,which limits the market application of SRM.In order to improve the competitiveness of SRM in all kinds of machines,it is necessary to further improve the operating efficiency of SRM.Therefore,in order to improve the operating efficiency of the machine,this paper studies and discusses the key problems of the calculation of machine iron loss,the influence of control parameters on machine iron loss,the establishment of machine model including iron loss and the multiobjective optimization design of machine including iron loss.The main contents of the paper are as follows:Aiming at the inaccuracy of the existing constant coefficient iron loss calculation model of ferromagnetic materials,this paper proposes a polynomial fitting model for calculating the loss of ferromagnetic materials to widen the application range of the loss and make it suitable for the calculation of SRM's iron loss.In view of the fact that SRM is affected by both rotational magnetization and alternating magnetization at the same time,while DC bias and small hysteresis loop still exist in the machine,this paper improves the existing loss calculation model and proposes three kinds of iron loss calculation model for SRM to improve the calculation accuracy.The iron loss of SRM is closely related to the magnetic density of the machine.In order to improve the calculation accuracy of the magnetic density and accelerate the time of magnetic density acquisition,this paper combines the magnetic equivalent circuit method with the finite element method to establish a fast and accurate method to obtain the magnetic density of each part,which is used for the calculation of the iron loss.Taking the three-phase 6/4 structure SRM for example,the accuracy of the iron loss calculation and the acquisition of magnetic density are verified through MATLAB/Simulink simulation and experiments,which laid a foundation for the subsequent research on the influence of control parameters on the machine's iron loss and the establishment of the machine model containing iron loss.Based on the established SRM iron loss calculation model and the method of obtaining the machine magnetic density rapidly and accurately,this paper analyzes the influence of the control parameters on the machine loss characteristics in the angle position control mode,current chopper control mode and voltage chopper control mode.To maintain the machine running in the same working condition,only two control parameters change each time while the other two control parameters remain unchanged in the analysis process.By analyzing the magnetic density distribution of the machine,the variation trend of the first 7 harmonic long-axis and short-axis magnetic density components of the stator yoke is obtained.Then the influence law of iron loss on control parameters with the above-mentioned three control modes is explained.Finally,some recommendation to reduce the machine iron loss are given from the perspective of control.In order to improve the simulation accuracy of the machine's dynamic performance and the accuracy of machine design optimization,and to shorten the machine design cycle,this paper proposes a SRM dynamic equivalent circuit model considering the machine iron loss.By analyzing the electromagnetic field distribution of the machine,the equivalent magnetic circuit model is established,and the Gauss-Seidel iterative method is improved to enhance the convergence speed in the calculation process.Then,according to the principle of magnetic equivalent circuit and equivalent electric circuit,the equivalent electric circuit model of the machine is established.In order to consider the influence of the iron loss on the dynamic performance,this paper proposes to divide each circuit component of the equivalent electric circuit model into energy storage part and loss part,and establishes the SRM dynamic equivalent circuit model considering the iron loss.According to the established dynamic equivalent electric circuit model,the current distribution of each part in the angular position control mode and current chopper control mode is simulated and analyzed.The feasibility and accuracy of the proposed model are verified by experiments.Finally,the error analysis of the simulation model is given.In order to improve the machine's operating efficiency from the machine body,this paper proposes a multiobjective optimization design method considering the iron loss from the perspective of machine design.For the problem of more SRM design parameters,a multilayer optimization design method is proposed.Firstly,the sensitivity analysis of the machine's parameters is carried out.The design parameters of the machine are divided into high sensitivity parameters and low sensitivity parameters,and then the design parameters of the machine are optimized with multilayer method.Due to SRM is a system with high coupled of mechanical,electromagnetic and thermal parameters,an electric-magnetic-thermal coupling modeling method is proposed based on the established dynamic circuit model and then the effect of iron loss on the design process is considered.Finally,a prototype is made and a prototype test platform is set up to verify the feasibility and effectiveness of the proposed method.