Design And Analysis Of A Novel Hybrid Rotor Permanent Magnet Synchronous Reluctance Machine

The permanent magnet-assisted synchronous reluctance machine combines the advantages of permanent magnet synchronous machine and synchronous reluctance machine to effectively improve the torque density,weaken the magnetic flux for wide speed range,and reduce the manufacturing cost,which has become a very popular machine candidate with good foreground.However,although the permanent magnet-assisted synchronous reluctance machine can produce higher reluctance torque and a certain magnetic torque,the two torque components in the traditional research and design cannot be fully utilized to generate the total torque.At the same time,the permanent magnet embedded in the flux barriers can only produce a relatively low air gap flux density,which contains large harmonics,resulting in large torque ripple and core loss,thus further limits the improvement of magnetic torque and efficiency.Moreover,the design of the flux barriers is limited by the design of the permanent magnet,which is not conducive to its optimization design to obtain a higher saliency ratio,thus greatly limits the increase of reluctance torque.Therefore,this thesis proposes a novel hybrid rotor permanent magnet synchronous reluctance machine.The rotor is composed of a permanent magnet rotor and a reluctance rotor in an axially symmetrical structure through a special assembling angle,which is not only beneficial to the optimization design of permanent magnets to improve the magnetic torque and reduce the torque ripple,but also beneficial to the design of flux barriers to improve the saliency ratio and mechanical strength.Moreover,the maximum values of the magnetic and reluctance torques can be superimposed at the same current phase angle,so that the two torque components can be fully utilized.Consequently,the machine performance,such as torque and power density,efficiency and torque ripple,can be comprehensively improved without increasing the difficulty of mechanical manufacturing and cooling,while the proposed machine has the advantages of flexible rotor structure design,simple processing technology,and high mechanical strength.In order to highlight the advantages of the proposed hybrid rotor permanent magnet synchronous reluctance machine,this thesis adopts the comparative research method.Based on the design of the traditional permanent magnet-assisted synchronous reluctance machine,the proposed machine is designed,and then the analysis by a quantitative comparison is performed.The detailed research work is as follows:(1)Firstly,the structure and main features of the traditional permanent magnet-assisted synchronous reluctance machine are introduced.Based on the coordinate transformation theory,the mathematical model of the perImanent magnet-assisted synchronous reluctance machine is studied.According to the design principle of the proposed machine,the topology of the novel hybrid rotor permanent magnet synchronous machine is established.By analyzing the mathematical models of permanent magnet synchronous machine and synchronous reluctance machine,the mathematical model of the novel hybrid rotor permanent magnet synchronous machine is established.(2)Secondly,a traditional permanent magnet-assisted synchronous reluctance machine is designed by the D2L method,and nominated as the basic model.Based on the specifications,dimensions and materials of the basic model,the novel hybrid rotor permanent magnet synchronous machine was designed and nominated as the proposed model:1)Based on the amount of permanent magnets in the basic model,the Latin cubic sampling method,Kriging method and genetic algorithm are used to optimize the permanent magnet rotor of the proposed hybrid rotor permanent magnet synchronous reluctance machine.The objective functions are to maximize the magnetic torque,to minimize the cogging torque.torque ripple and core loss.The permanent magnet thickness d and the angular width ? of the magnetic pole are determined.2)Considering that the permanent magnet removal greatly releases the mechanical stress of the reluctance rotor,and the width of the rib of flux barriers has a significant influence on the electromagnetic and mechanical performance,the Mises stress analysis is carried out for the basic and proposed models.Then the width of the rib of the flux barriers in the reluctance rotor dr is determined such that the proposed model and the basic model have similar geometric and mechanical stress conditions.3)In order to allow the maximum values of the magnetic torque and the reluctance torque to meet at the same current phase angle,the superposition relationship of the magnetic torque and the reluctance torque are studied under the different axial assembling angles ? of two rotors.Then the optimal axial assembling angle is determined,that is,only ?=45° can fully utilize the torque component.(3)The electromagnetic performance of the basic model and proposed model are then quantitatively analyzed and compared by the finite element method.The advantages of the proposed model are verified by comparing the air gap flux density,back electromotive force,torque characteristics,maximum electromagnetic torque and torque ripple,power factor and efficiency.(4)Finally,an experimental prototype of the proposed model was developed,and the back electromotive force at the no-load condition and the average torque at the load condition were tested,and then compared with the simulation results by the finite element method.The results show good agreement,which verify the correctness of the simulation results and the proposed machine design approach.