• Title/Summary/Keyword: Reduction of cogging torque

Search Result 88, Processing Time 0.042 seconds

Cogging Torque Reduction in Permanent-Magnet Brushless Generators for Small Wind Turbines

  • Chung, Dae-Won;You, Yong-Min
    • Journal of Magnetics
    • /
    • v.20 no.2
    • /
    • pp.176-185
    • /
    • 2015
  • We present the design optimization of the magnetic pole and slot design options that minimize the cogging torque of permanent-magnet (PM) brushless generators for small wind turbine generators. Most small wind-turbines use direct-driven PM generators which have the characteristics of low speed and high efficiency. Small wind-turbines are usually self-starting and require very simple controls. The cogging torque is an inherent characteristic of PM generators, and is mainly caused by the generator's geometry. The inherent the cogging torque can cause problems during turbine start-up and cut-in in order to start softly and to run a power generator even when there is little wind power during turbine start-up. Thus, to improve the operation of small turbines, it is important to minimize the cogging torque. To determine the effects of the cogging torque reductions, we adjust the slot opening width, slot skewing, mounting method of magnets, magnet shape, and the opening and combinations of different numbers of slots per pole. Of these different methods, we combine the methods and optimized the design variables for the most significant design options affecting the cogging torque. Finally, we apply to the target design model and compare FEA simulation and measured results to validate the design optimization.

Sensitivity Analysis of Design Parameters for Reduction of Cogging Torque in Brushless DC Motors used for Automobile Part (자동차 부품용 BLDC 모터 내의 코깅 토크 저감을 위한 설계 변수의 민감도 해석)

  • 황상문
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.6 no.2
    • /
    • pp.235-243
    • /
    • 1998
  • For motor operation at low speeds and loads, torque pulsation by the cogging torque is often a source of vibration and control difficulty. In this paper, the magnetic field of a motor is calculated by finite element method. The periodic cogging torque is determined using Maxwell stress method and time stepping method, and then decomposed using fourier series expansion, The purpose of this paper is to characterize design parameters on the cogging torque and to design a permanent magnet motor with a cogging torque less vulnerable to vibration, without sacrificing the motor performance. The design parameters include stator slot width, permanent magnet slot width, airgap length and magnetization direction. A new design with a less populated frequency spectrum of the cogging torque is proposed after characterizing individual effect of design parameters. Magnet pole edge shaping, by gradually increasing the cogging torque with reduced higher harmonics.

  • PDF

A Design on Reduction Cogging Torque of Dual Generator Radial Flux Permanent Magnet Generator for Small Wind Turbine

  • Lee, Gyeong-Chan;Jung, Tae-Uk
    • Journal of Electrical Engineering and Technology
    • /
    • v.8 no.6
    • /
    • pp.1590-1595
    • /
    • 2013
  • In this paper, the design for an electromagnetic structure and reduction cogging torque of a dual generator structured RFPM generator, which is a combination of the inner- and outer-rotor types, has been proposed. We call this a dual generator radial flux permanent magnet generator. To reduce the cogging torque, firstly, stator tooth pairing was designed; secondly, stator displacement was designed and finally, stator tooth pairing and stator displacement were carried out simultaneously. We found the optimal design condition about stator tooth pairing angle combination and stator displacement angle for cogging torque minimization. As a result, a cogging was reduced by 93.3[%] by this study.

The Equilibrium Design of Radial Magnetic Force for Reduction of Vibration in IPM type BLDC Motor

  • Lee, Gyeong-Deuk;Kim, Gyu-Tak
    • Journal of Electrical Engineering and Technology
    • /
    • v.11 no.2
    • /
    • pp.377-382
    • /
    • 2016
  • In this paper, influence of vibration on cogging torque and Radial Magnetic Force(RMF) imbalance was investigated in the IPM type BLDC motor. Design of cogging torque reduction and the RMF equilibrium was proceed applied to Design of Experiment(DOE). Vibration test results, the RMF imbalance was confirmed that a significant impact of vibration.

The Design of Radial Magnetic Force Equilibrium for Reduction of Vibration and Noise in IPM Type BLDC Motor (IPM type BLDC 전동기의 진동 및 소음 저감을 위한 가진력 평형화 설계)

  • Jeong, Tae-Seok;Cho, Gyu-Won;Kim, Gyu-Tak
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.62 no.11
    • /
    • pp.1535-1540
    • /
    • 2013
  • In this paper, the Radial Magnetic Force(RMF) and cogging torque which cause vibration and noise in IPM type BLDC motor were analyzed. The cogging torque and RMF cause electromagnetic vibration. So, a notch was installed for the equilibrium of RMF and cogging torque reduction. The notch was analyzed by using a Fourier Series for the energy distribution of the air-gap. The equilibrium of RMF and the reduction of cogging torque were performed by a Design Of Experiment(DOE) with the notch. Also, operating characteristics and efficiency were analyzed and compared.

The Inductance Computation of IPMSM using Direct-current Diminution Test (직류감쇄시험법에 의한 IPMSM의 인덕턴스 산정)

  • Cho, Gyu-Won;Jo, Jae-Ok;Woo, Seok-Hyeon;Jang, Ki-Bong;Kim, Gyu-Tak
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.61 no.2
    • /
    • pp.209-215
    • /
    • 2012
  • This paper deals with a reduction of cogging torque and estimate of inductance for IPMSM. The flux barriers(Barrier) and the auxiliary slot(Notch) for the reduction of cogging torque was installed for increase of driving characteristic in IPMSM. The cogging torque, driving torque and inductance are analyzed by using FEM(Finite Element Method) and the results of inductance calculation are compared to experimentation ones.

Cogging Torque Reduction of Interior Permanent Magnet Motor Using Statistical Method (통계적 기법을 이용한 매입형 영구자석 전동기의 코깅토크 저감)

  • Kim, Jung-Gyo;Lee, Ju
    • The Transactions of the Korean Institute of Electrical Engineers B
    • /
    • v.55 no.6
    • /
    • pp.287-291
    • /
    • 2006
  • Recently, various applications of permanent-magnet(PM) electric motor have been more increased. Compared with the other electric motors, PM electric motor has cogging torque which results from the interaction between PM of rotor and slot-teeth structure of stator. Audible noise and vibration is caused by this cogging torque. So, the reduction of cogging torque is main designing goal of PM electric motor. The purpose of this paper is to realize the decrease of cogging torque using new experimental design and response surface analysis which is one of the statistical methodologies.

Study on Cogging Torque Reduction for Small Wind Turbine AFPM Generator of Double Stator Structure (이중 고정자 구조의 소형풍력터빈용 AFPM 발전기의 코깅토크 저감에 관한 연구)

  • Jung, Tae-Uk;Bae, Byung-Duk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.26 no.2
    • /
    • pp.71-77
    • /
    • 2012
  • The cogging torque is important to the cut-in wind speed. And, it causes the acoustic noise and the vibration on the machine. This paper presents a 3D FEA(Finite Element Analysis) to evaluate the effect of magnet skew and stator displacement on cogging torque reduction, for double core AFPM(Axial Flux Permanent Magnet) generator. As a result, the magnet skew and the stator side displacement are proved excellent techniques to reduce the cogging torque.

Optimal Design of Stator of Permanent Magnet Motors Having Closed Slot For The Cogging Torque Reduction (폐슬롯 형상을 가진 영구 자석형 동기 전동기의 코깅 토크 저감을 위한 고정자 치수 최적화)

  • Chun, J.S.;Hong, S.K.;Yoon, J.S.;Jung, H.K.
    • Proceedings of the KIEE Conference
    • /
    • 1995.07a
    • /
    • pp.59-61
    • /
    • 1995
  • This paper presents the cogging torque analysis of the permanent magnet type AC servo motor which have the closed slot structure. Generally, existence of the slot opening causes the cogging torque. But the cogging torque exists in this type motor(having closed slot structure) because the bridge part is saturated by the rotor flux. In this paper, the finite element analysis is used to calculate the cogging torque and the rated torque. As the size of the bridge part-the thickness and the width-changes, the cogging torque and the rated torque are obtained repeatedly like as upper procedures. Finally, the trends of the cogging torque and the rated torque versus the size of the bridge part are obtained from this analysis procedures. By this approach, the optimal geometry of the bridge part can be found which minimize the cogging torque satisfying the required value of the rated torque.

  • PDF

Reduction of Cogging Torque of BLDC Motor by Sinusoidal Air-Gap Flux Density Distribution (BLDC 전동기의 정현적 공극 자속밀도 구현에 의한 코깅 토크 저감)

  • Kim, Samuel;Jeong, Seung-Ho;Rhyu, Se-Hyun;Kwon, Byung-Il
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.56 no.1
    • /
    • pp.57-65
    • /
    • 2007
  • Along with the development of power electronics and magnetic materials, permanent magnet (PM) brushless direct current (BLDC) motors are now widely used in many fields of modern industry BLDC motors have many advantages such as high efficiency, large peak torque, easy control of speed, and reliable working characteristics. However, Compared with the other electric motors without a PM, BLDC motors with a PM have inherent cogging torque. It is often a principle source of vibration, noise and difficulty of control in BLDC motors. Cogging torque which is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance can be reduced by sinusoidal air-gap flux density waveform due to reduction of variation of magnetic reluctance. Therefore, this paper will present a design method of magnetizing system for reduction of cogging torque and low manufacturing cost of BLDC motor with isotropic bonded neodynium-iron-boron (Nd-Fe-B) magnets in ring type by sinusoidal air-gap flux density distribution. An analytical technique of magnetization makes use of two-dimensional finite element method (2-D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation. In addition, For optimum design of magnetizing fixture, Factorial design which is one of the design of experiments (DOE) is used.