scholarly journals Mitigation Method of Slot Harmonic Cogging Torque Considering Unevenly Magnetized Permanent Magnets in PMSM

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3887
Author(s):  
Jeong ◽  
Lee ◽  
Hur

This paper presents a mitigation method of slot harmonic cogging torque considering unevenly magnetized magnets in a permanent magnet synchronous motor. In previous studies, it has been confirmed that non-uniformly magnetized permanent magnets cause an unexpected increase of cogging torque because of additional slot harmonic components. However, these studies did not offer a countermeasure against it. First, in this study, the relationship between the residual magnetic flux density of the permanent magnet and the cogging torque is derived from the basic form of the Maxwell stress tensor equation. Second, the principle of the slot harmonic cogging torque generation is explained qualitatively, and the mitigation method of the slot harmonic component is proposed. Finally, the proposed method is verified with the finite element analysis and experimental results.

Author(s):  
Ahmad Sofian Saari Saari ◽  
Dahaman Ishak

<span lang="EN-IN">This paper presents a design of 15-slot/12-pole, five-phase, surface-mounted permanent magnet synchronous motor (PMSM).  The five-phase PMSM can be an attractive solution to few applications that demand fault tolerant capability such as in aerospace engineering and electric propulsion. The motor model is first investigated based on the implementation of analytical method. The analytical method derived from the subdomain model of the permanent magnet machine is initially applied to estimate the magnetic flux density distributions for the radial component <em>B</em><sub>r</sub> and the tangential component <em>B</em><sub>t</sub> in the machine air gap. Other important motor characteristics such as phase back-EMF, line back-EMF, cogging torque and electromagnetic torque are also calculated. The analytically calculated results are then compared with the numerical method in a 2D finite element analysis. Additionally, the capability of this PMSM model against faulty conditions are further investigated. The results show that the analytical model of the 15-slot/12-pole, five-phase PMSM provides very accurate motor performance within acceptable error margin. For instance, the average electromagnetic torques, inclusive of the cogging torque, as computed by the analytical and numerical methods are 5.53Nm and 5.33Nm respectively, yielding an error of 3.6%. During faulty conditions, the PMSM can possibly continue to operate with lower output torque, about 60% to 80% of its rated torque, when one-phase or two phase windings are out of service.</span>


2021 ◽  
Vol 13 (1) ◽  
pp. 11
Author(s):  
Xiao He ◽  
Guangqing Bao

Hybrid permanent magnet synchronous motor (HPMSM) has attracted increased attention in recent years due to its adjustable air gap flux. However, as a result of the cross-coupling effect of high- and low-coercive permanent magnets, the precise magnetic adjustment of HPMSM has become increasingly difficult. In order to weaken the cross-coupling effect, two methods of adding magnetic barrier and exciting coil are adopted in this paper. First, the equivalent magnetic circuit model is established, and the theoretical rationality of the weakening method is analyzed. Second, the electromagnetic performance of two weakening methods are analyzed based on the finite element analysis. Finally, the rationality of the theoretical analysis is verified, which provides the structure basis for the precise magnetic adjustment of the hybrid permanent magnet motor.


2017 ◽  
Vol 18 (1) ◽  
pp. 133-145
Author(s):  
Seyed Asghar Gholamian ◽  
Hamid Reza Gholinejad

Magnets placement effects on permanent magnet motors performance, because of its different magnetic flux density distribution. Therefore, different types of magnet placement should be examined experimentally or by valid simulations. In this paper, first, an interior permanent magnet synchronous motor (IPMSM) called spoke type with specifications related to the propulsion of ships is designed and then optimized by ant colony algorithm to increase the torque-to-volume ratio. The design procedure and its formulas presented as simple as possible. Then, to verify the optimization results of the optimized motor, a Two-dimensional finite element analysis (FEA) is done. Also in this analyze the core and the slot saturation was studied.


2011 ◽  
Vol 383-390 ◽  
pp. 1825-1830
Author(s):  
Gui Hong Feng ◽  
Shuang Li ◽  
Min Zhao ◽  
Bing Yi Zhang

Squirrel-cage rotor line-start permanent magnet synchronous motor can not meet the heavy lifting, frequent starting conditions for the lifting requirements. In order to solve the difficult problem of starting caused by the squirrel-cage rotor line-start permanent magnet synchronous motor (LS-PMSM), a novel wound rotor line-start permanent magnet synchronous motor is proposed in this paper, which uses wound rotor to replace squirrel cage rotor. In this paper, the finite element analysis method is adopted to simulate and analyze the starting process of the motor, through reasonably determining the value of the external rotor resistance, the starting performance of the motor has improved greatly, and lead the motor smoothly into synchronous speed. The simulation results show the correctness and effectiveness of the research methods.


Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 610
Author(s):  
Dong-Woo Nam ◽  
Kang-Been Lee ◽  
Hyun-Jo Pyo ◽  
Min-Jae Jeong ◽  
Seo-Hee Yang ◽  
...  

The spoke-type permanent magnet synchronous motor (PMSM), which is a general ferrite magnetic flux-concentrated motor, has a low portion of reluctance torque at the total torque magnitude. Therefore, as a way to increase the reluctance torque, there is a double-layer spoke-type PMSM that can maximize the difference in inductance between the d-axis and the q-axis. However, in the double-layer spoke-type PMSM, cogging torque, torque ripple, and total harmonic distortion (THD) increase with reluctance torque, which is the main cause of vibration and noise. In this paper, a method is proposed that provides the same effect as skew without dividing stages of the permanent magnet by dividing the core of the rotor into two types so that it is easy to manufacture according to the number of stages, unlike extant skew methods. Based on the method, the reduction in cogging torque and THD was verified by finite element analysis (FEA).


Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2406 ◽  
Author(s):  
Cezary Jędryczka ◽  
Dawid Danielczyk ◽  
Wojciech Szeląg

This paper deals with the torque ripple minimization method based on the modulation of the phase currents of the permanent-magnet synchronous motor (PMSM) drive. The shape of the supply current waveforms reducing the torque ripple of the machine considered was determined on the basis of finite element analysis (FEA). In the proposed approach, the machine is supplied by a six-leg inverter in order to allow for the injection of zero sequence current harmonics. Two test PMSMs with fractional-slot concentrated windings (FSCW) and surface-mounted permanent magnets (SPMs) have been examined as a case study problem. Wide-range fractional analyses were performed using developed numerical models of the electromagnetic field distribution in the considered machines. The results obtained show that the level of torque ripple in FSCW PMSMs can be effectively reduced by the modulation of the phase currents under the six-leg inverter supply.


2019 ◽  
Vol 70 (3) ◽  
pp. 218-226 ◽  
Author(s):  
Vasilija Sarac

Abstract The development of the robotics and the automation and the need for the motors that can work in the applications that require high speed, precision and increased efficiency have led to the increased use of permanent magnet synchronous motors and their continuous development in terms of improving their performance. Cogging torque is one of the features of these types of the motors that deteriorate motor performance especially at low speeds. Therefore, in this paper the method of genetic algorithms (GA) is applied as an optimization tool, for minimizing the cogging torque without changing the other important operating parameters like output power, torque or current. Even more, the optimized motor model has improved efficiency compared to the starting model and has the decreased weight of the permanent magnets. The optimization is done by changing the rotor design in terms of the magnet thickness, pole span and shape of the magnets. Finite elements (FE) models of the optimized and the basic motor were derived and from them the flux density distribution in the motor cross section and in the air gap was calculated. In addition, the improvement of the motor operation is observed from the torque characteristics calculated by the FE models.


2020 ◽  
Vol 64 (1-4) ◽  
pp. 79-89
Author(s):  
Yan Liu ◽  
Wenliang Zhao ◽  
Xue Fan ◽  
Xiuhe Wang ◽  
Byung-il Kwon

This paper proposes an optimal design for a surface-mounted permanent magnet motor (SPMM) to reduce torque pulsations, including cogging torque and torque ripple, by using multi-grade ferrite magnets. Based on a conventional SPMM with single-grade ferrite magnets, the proposed SPMM is designed with four-grade ferrite magnets and then optimized to minimize torque pulsations by maintaining the required torque, utilizing the Kriging method and a genetic algorithm. The results obtained by the finite element analysis show that the optimized SPMM with multi-grade ferrite magnets exhibits improved airgap flux density distribution with highly reduced cogging torque and torque ripple by maintaining the same average torque, as compared to the conventional SPMM. Furthermore, the analysis of the working points for the multi-grade ferrite magnets reveals that the optimized SPMM has good durability against the irreversible demagnetization.


2012 ◽  
Vol 455-456 ◽  
pp. 1160-1168
Author(s):  
Shuang Hui Hao ◽  
Zi Li Tang ◽  
Rui Zheng Long ◽  
Ming Hui Hao

Design optimization and analysis of the high power linear permanent magnet synchronous motor for aircraft launch are presented in this paper. This motor has a decentralized stator that runs the entire length of travel. A plate with an array of permanent magnets is used as the secondary. This structure enables easier manufacture, flexible system assembling, and autonomous decentralized control employed for energy saving. The thrust and cogging force of the motor are highly affected by the motor structural parameters. The influences of these structural parameters on the thrust and cogging force are analyzed by finite element analysis method; experiment studies are carried out to support the theoretical analysis.


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