Design And Analysis Of Permanent Magnet Assisted Synchronous Reluctance Machine

With the development of the modern industrial technology,the demand for the rapid development of permanent magnet assisted synchronous reluctance machine(PMASynRM)is increased.The pros and cons of its design quality and the development of performance analysis techniques have become the focus of attention in the motor industry.Aiming at the two major technical problems of the torque ripple and low design efficiency,this paper starts from the decomposition method of the air-gap flux density,the optimal parametric design of the flux barriers,the parameterized design model of the machine and the comprehensive performance analysis method,and carries out relevant research according to the design theory,proposed scheme and experimental verification,so as to improve the design quality and efficiency of PMASynRM.Aiming at the problem that the torque harmonics are complex,the production mechanism of torque is not clear,the torque calculation model is not accurate and the design freedom of flux-barrier parameters is high,this paper proposes an effective torque calculation model considering air-gap field time-space harmonics using the finite element method(FEM)combined with two-dimensional fast Fourier transform(2D-FFT).This model can be used to compute the contribution of air-gap field time-space harmonics to average torque and torque ripple,so as to make the relationship between the torque and the air-gap field time-space harmonics clearer.On this basis,in the design process,it is useful to graph the variation of the harmonic torques due to different combinations of the flux-barrier angles on some maps,and meanwhile it is important to point out that the harmonic torques are produced by air-gap field time-space harmonics that mainly contribute to torque ripple.Through these maps,the change rules of the harmonic torques under different combinations of flux-barrier angles can be analyzed.Based on these rules,the flux-barrier angles with a lower torque ripple can be directly determined.In order to further suppress the torque ripple of PMASynRM,an improved flux-barrier geometry configuration is proposed in this paper.The flux-barrier geometry configuration has two remarkable features.Firstly,its flux barriers are step-shaped.Secondly,the widths of multi-flux barriers in the middle regions are changing in a gradient style.In the design process of the proposed flux-barrier geometry configuration,the design idea of the parametric classification is adopted in order to solve the problem of many and miscellaneous parameters to be optimized.On the basis,the gradual parameters and step-shaped parameters are optimized by the magnetic field analytical modeling and Taguchi method in order to make the flux-barrier geometry configuration work well.Finally,the design scheme of the optimal parameters the proposed the flux-barrier geometry configuration with a low torque ripple is found.Aiming at the problem of the large numbers of the adjustable structural design parameters,the coupled relations among these parameters,the tedious parameter selection process and a low design efficiency,this paper proposes a design and performance analysis method of high efficiency PMASynRM based on the split ratio.An accurate analytical model,which considers the saturation of iron ribs and asymmetric saturation of rotor islands,and a geometric structure corresponding to the split ratio are firstly established.On the basis,the influence of the split ratio on the various electromagnetic performance is analyzed and reasearched by the proposed design and performance analysis method,and the optimal split ratio which meet the design requirements is determined based on the principle of maximum efficiency.Based on the functional relationship between the split ratio and the structural parameters,the design scheme of the machine is quickly completed.The proposed method has the advantages of versatility,easy application and high efficiency.Finally,a 20 k W PMASynRM is designed using the above analysis and design method,and a prototype is made.The design cycle is short and the prototype has the characteristics of high efficiency and low torque ripple.