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In view of the problem of large torque ripple and poor output performance of permanent magnet synchronous motor, a new topology of asymmetric magnetic pole permanent magnet synchronous motor is proposed, and the torque ripple of this motor structure and the suppression method are analyzed. First, the equivalent magnetic circuit method and Lorentz force law are used to derive the analytical formula of torque ripple of the motor. Then, based on the analytical formula, the parameters of permanent magnet of the asymmetric magnetic pole permanent magnet synchronous motor are optimized and verified by finite element software simulation; on this basis, the method of rotor eccentricity is used to further weaken the torque ripple of the motor, and the optimal eccentricity distance is analyzed. The research shows that when the parameters of the magnetic pole of the asymmetric magnetic pole permanent magnet synchronous motor is appropriate, the harmonic content of the air gap magnetic density of the optimized motor is greatly reduced, and the motor has good output characteristics, and the torque ripple is reduced to 5.4%. Finally, the prototype is trial‐manufactured and tested. The results show that after optimization, the cogging torque of the motor is reduced, the torque output performance is improved, and the overall motor performance is improved. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A dual-modulation axial magnet gear motor （DAMGM） was proposed to address the shortcomings of the axial magnet gear motor （AMGM）, which has a large overall size and low torque density（≤70 kN·m/m3）. Two magnetizing rings on the high-speed and low-speed sides were used to modulate the low-speed rotor in the DAMGM, and the non-magnetic parts in both magnetic magnetizing rings were permanent magnets, effectively improving the output torque of the low-speed rotor. In addition, compared to the existing AMGM, the drive motor was placed inside the high-speed permanent magnet rotor of the DAMGM, reducing the overall axial size and significantly improving the torque density of the low-speed rotor（150 kN·m/m3）. Aiming at the problems of long calculation time and serious waste of computer resources in the existing 3D finite element method, a 3D analysis method of DAMGM based on the cylindrical coordinate system was presented. According to three boundary conditions of the magnetizing ring, the mathematical and physical models of the modulated DAMGM air gap magnetic field and electromagnetic torque were established. The calculation results are not only accurate （compared with the 3D finite element method, the average calculation error is less than or equal to 5%）, but also the calculation time is short （only 1/10 of the 3D finite element method）, facilitating the analysis, comparison, and optimization of different parameter structures in the DAMGM.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A uniform magnetic density distribution in the air gap is key for the Lorentz magnetic bearing to achieve high precision control and large torque output. To overcome the small magnetic field strength in an explicit magnetic bearing and a high magnetic density fluctuation rate in an implicit Lorentz magnetic bearing, a second air gap design method is proposed based on the maximum magnetic density distribution in the winding area. A novel Lorentz bearing with a double second air gap is designed. The maximum magnetic field strength in the winding area is calculated by the finite element method, and the structure of the double second air gap is designed. To reduce the calculation error of the magnetic field strength, the division of the reluctance by the magnetic induction line is proposed. The reluctance calculation formula is given. Based on Ohm's law, the calculation of the magnetic field strength is obtained. Finally, a prototype of the novel Lorentz magnetic bearing is made. The magnetic field strength in the winding area and the magnetic density fluctuation rate are measured with a magnetic density measurement instrument. The maximum magnetic flux density in the winding area is 0.631 T, and the magnetic field strength is 0.58%. Less difference is found between the measurement result and the finite element result. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the problem of permanent magnet loss of permanent magnet synchronous motor, the method of finite element analysis is used in the proposed study to establish Ansoft Maxwell finite element analysis model of 3 kW small permanent magnet synchronous motor. The method of reducing the coercive force and residual magnetic induction of permanent magnet materials is adopted to simulate the permanent magnet demagnetization failure, and the finite element models of the motor under different degrees of loss of magnetism are established. The results show that when the permanent magnet synchronous motor has a 50% loss of field fault, the air gap magnetic density decreases in varying degrees at no-load and load, the no-load air gap magnetic field attenuates by 53.0% and the load decays by 19.8%. Additionally, the induced potential decreases linearly, the current nonlinearity increases, and the fundamental and harmonic components of the induced potential decrease in varying degrees. The motor output torque decreases with the increase of the loss of field, and when the degree of loss of excitation reaches 50%, the permanent magnet motor cannot reach the rated torque output state. This result can be used as an important basis for the diagnosis of loss of excitation fault. [ABSTRACT FROM AUTHOR]

Aiming at the vibration and noise problem of permanent magnet synchronous motor caused by high cogging torque，the structure of auxiliary slot on rotor surface was optimized. Through the principle of permanent magnet synchronous motor cogging torque，the influence of rotor structure on motor cogging torque was analyzed，and the relationship between the structure of the auxiliary slot on the rotor surface and the cogging torque of the motor was discussed. A permanent magnet synchronous motor model with 8 poles and 48 slots was built by finite element method. With the built-in permanent magnet synchronous motor model as the carrier，by changing the air gap flux density harmonic component，multi-objective genetic algorithm was used to calculate the optimal solution of the number，position and depth of the auxiliary slot，and the optimal design scheme of the auxiliary slot structure was obtained. The results indicate that the cogging torque of the built-in permanent magnet synchronous motor can be effectively reduced by using the optimized rotor surface auxiliary slot structure and increase the amplitude of air-gap magnetic dense basis，and reduce the amplitude of 5th and 7th harmonics. The peak torque of the cogging slot is reduced by 76. 2%，and the motor performance is not reduced. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical & Electrical Engineering is the property of Mechanical & Electrical Engineering Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)