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Acoustic Noise and Vibration Reduction of Coreless Brushless DC Motors with an Air Dynamic Bearing

  • Yang, lee-Woo;Kim, Young-Seok;Kim, Sang-Uk
    • Journal of Electrical Engineering and Technology
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    • v.4 no.2
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    • pp.255-265
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    • 2009
  • This paper presents the acoustic noise and mechanical vibration reduction of a coreless brushless DC motor with an air dynamic bearing used in a digital lightening processor. The coreless brushless DC motor does not have a stator yoke or stator slot to remove the unbalanced force caused by the interaction between the stator yoke and the rotor magnet. An unbalanced force makes slotless brushless DC motors vibrate and mechanically noisy, and the attractive force between the magnet and the stator yoke increases power consumption. Also, when a coreless brushless DC motor is driven by a $120^{\circ}$ conduction type inverter, high frequency acoustic noise occurs because of the peak components of the phase currents caused by small phase inductance and large phase resistance. In this paper, a core-less brushless DC motor with an air dynamic bearing to remove mechanical vibration and to reduce power consumption is applied to a digital lightening processor. A $180^{\circ}$ conduction type inverter drives it to reduce high frequency acoustic noise. The applied methods are simulated and tested using a manufactured prototype motor with an air dynamic bearing. The experimental results show that a coreless brushless DC motor has characteristics of low power consumption, low mechanical vibration, and low high frequency acoustic noise.

Characteristics Analysis and Comparison of Careless and Slotless BLDC Motor used in Digital Lightening Processor Motor with Air-Dynamic Bearing (공기 동압 베어링을 갖는 디지털 라이트닝 프로세서 모터용 코어리스 및 슬롯리스 BLDC 모터의 특성 분석 및 비교)

  • Yang, Iee-Woo;Kim, Young-Seok;Kim, Sang-Uk
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.6
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    • pp.1039-1046
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    • 2007
  • This paper presents the analysis for power consumption, mechanical vibration and acoustic noise characteristics of the Coreless and Slotless Brushless DC motor in Digital Lightening Processor(DLP) Motor with the Air-Dynamic Bearing. The Coreless BLDC motor has not the stator yoke as well as the stator slot to remove the unbalance force by the interaction between the stator yoke and Air-Dynamic Bearing clearance. The assembling tolerance and the processing error make the air-gap difference between the magnet and the stator yoke .which occurs the unbalanced electro-magnetic force in the Slotless BLDC motor. It imposes the air-dynamic bearing on the disturbance force and makes the Air-Dynamic Bearing vibrated and noised. Also, The attractive force between the magnet and the silicon steel stator yoke increases the power consumption. In this paper, the power consumption, mechanical vibration and acoustic noise of the Coreless BLDC motor and the Slotless BLDC motor with the silicon steel stator yoke are simulated, analyzed, and tested using the manufactured proto-type motors with Air-Dynamic bearing. The simulated and tested results present that the Coreless BLDC motor without the silicon steel stator yoke has the lower mechanical vibration and noise ,and lower power consumption than the Slotless BLDC motor with the silicon steel stator yoke in Digital Lightening Processor Motor with Air-Dynamic Bearing.

Design and Performance Analysis of Coreless Axial-Flux Permanent-Magnet Generator for Small Wind Turbines

  • Chung, Dae-Won;You, Yong-Min
    • Journal of Magnetics
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    • v.19 no.3
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    • pp.273-281
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    • 2014
  • This paper presents an innovative design for a low-speed, direct-drive, axial-flux permanent-magnet (AFPM) generator with a coreless stator and rotor that is intended for application to small wind turbine power generation systems. The performance of the generator is evaluated and optimized by means of comprehensive 3D electromagnetic finite element analysis. The main focus of this study is to improve the power output and efficiency of wind power generation by investigating the electromagnetic and structural features of a coreless AFPM generator. The design is validated by comparing the performance achieved with a prototype. The results of our comparison demonstrate that the proposed generator has a number of advantages such as a simpler structure, higher efficiency over a wide range of operating speeds, higher energy yield, lighter weight and better power utilization than conventional machines. It would be possible to manufacture low-cost, axial-flux permanent-magnet generators by further developing the proposed design.

Magnetic Field Calculation and Multi-objective Optimization of Axial Flux Permanent Magnet Generator with Coreless Stator Windings

  • Zhu, Jun;Li, Shaolong;Song, Dandan;Han, Qiaoli;Li, guanghua
    • Journal of Electrical Engineering and Technology
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    • v.13 no.4
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    • pp.1586-1595
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    • 2018
  • For the problem that the complexity of 3-D modeling and multi parameter optimization, as well as the uncertainty of the winding factor of axial flux permanent magnet generator with coreless windings. The complex 3-D model was simplified into 2-D analytic model, and an analytical formula for the winding factor that adapting different coreless stator winding is proposed in this paper. The analytical solution for air-gap magnetic fields, no-load back EMF, electromagnetic torque, and efficiency are calculated by using this method. The multiple objective and multivariable optimization of the maximum fundamental and the minimum harmonic content of back EMF are performed by using response surface methodology. The proposed optimum design method was applied to make a generator. The generator was tested and the calculated results are compared with the proposed method, which show good agreements.

Comparison on the Airgap Flux Density of High-Speed Slotless Machines with Radial Magnetization and Halbach Array PM Rotor (반경방향 착자형과 Halbach 배열형 영구자석 회전자를 갖는 고속 슬롯리스 기기의 공극자속밀도 특성 비교)

  • Jang, Seok-Myeong;Jeong, Sang-Seop;Ryu, Dong-Wan
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.7
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    • pp.315-322
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    • 2001
  • High speed brushless permanent magnet(PM) machines need a key technology to minimize the iron core losses in stator and the eddy current losses in the retained sleeve and magnets caused by slotting harmonics. Thus, slotless or iron-coreless brushless PM machines have been applied for a very high rotational speed and/or the ripple-free torque. Unfortunately, slotless or coreless PM machines have lower open-circuit field than slotted and/or iron-cored types, which cause to reduce power density. Fortunately, Halbach array can generate the strong magnetic field systems without additional magnetic materials. In this paper, the 4-pole Halbach array is applied to the high speed machine and is compared with the radial magnetized PM array in field system. The iron-/air-cored stator of PM machine is constructed with/without winding slots. Open circuit magnetic fields of each type are presented from the analytical method and finite element method. Consequently, it is confirmed that the Halbach array field system with slotless stator is more suitable to the high speed motor because it has high flux density, sinusoidal flux distribution than others.

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Characteristics Analysis of a Direct-Drive AFPM Generator (직접 구동 AFPM 풍력발전기의 특성해석)

  • Seo, Young-Taek;Kim, Hyoung-Gil;Kong, Jeong-Sik;Kim, Chul-Ho;Oh, Chul-Soo
    • Proceedings of the KIEE Conference
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    • pp.687-689
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    • 2003
  • Recently, issues regarding environment and the diversification of dependence in oil are watched with keen interest. Wind power attracts most interest because of its high-energy efficiency with environment friendly functions. The paper discusses the development of a coreless axial-flux permanent magnet (AFPM) generator for a wind power system. Analyzed the Coreless AFPM generator by electromagnetic, and designed wind power generator with this. The 3 phase output of stator is rectified and fed to a common do link. The overall machine structure has high compactness and lightness, because of the lack of the iron core. The test results with a resistive load confirm the satisfactory operation of generator. Compared with conventional generator, the design has lower weight, lower Power loss and improved efficiency.

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A Study on AFPM(Axial Flux Permanent Magnet)Motor without Stator Corer (코어없는 축방향 영구자석형 전동기에 관한 연구)

  • Park, Jong-Chan;Choi, Hae-Ryong;Choe, Gyu-Ha
    • The Transactions of the Korean Institute of Power Electronics
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    • v.11 no.3
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    • pp.284-291
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    • 2006
  • Recently with the motorizing of electric home appliances and car systems, there is increasing interest in high efficiency electric motors. Thus, the present study described the operating characteristics of coreless AFPM motor that is highly efficient in high speed driving, and discussed its electric characteristics from the perspective of design. In particular, we examined back electromotive force and the magnetic field characteristic in slits, which have significant effects on the characteristic of the motor, and conducted simulation and experiment on control characteristic according to inductance characteristic. This study analyzed torque speed and efficient operation characteristic as well as control characteristic through comparing the result of motor design with the result of output characteristic experiment based on the electric network method. Furthermore, we evaluated vibration and noise that may occur due to the absence of core.

Analysis and Optimization of the Axial Flux Permanent Magnet Synchronous Generator using an Analytical Method

  • Ikram, Junaid;Khan, Nasrullah;Junaid, Qudsia;Khaliq, Salman;Kwon, Byung-il
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.257-265
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    • 2017
  • This paper presents a 2-D analytical method to calculate the back EMF of the axial flux permanent magnet synchronous generator (AFPMSG) with coreless stator and dual rotor having magnets mounted on both sides of rotor yoke. Furthermore, in order to reduce the no load voltage total harmonics distortion (VTHD), the initial model of the coreless AFPMSG is optimized by using a developed analytical method. Optimization using the 2-D analytical method reduces the optimization time to less than a minute. The back EMF obtained by using the 2-D analytical method is verified by a time stepped 3-D finite element analysis (FEA) for both the initial and optimized model. Finally, the VTHD, output torque and torque ripples of both the initial and optimized models are compared with 3D-FEA. The result shows that the optimized model reduces the VTHD and torque ripples as compared to the initial model. Furthermore, the result also shows that output torque increases as the result of the optimization.

Characteristics Analysis of Aixal Flux Permanent Magnet core-less motor (축 방향 자속 코어레스 전동기의 특성 해석)

  • Seo, Young-Taek;Kong, Jeong-Sik;Kim, Chul-Ho;Kim, Hyoung-Gil;Oh, Chul-Soo
    • Proceedings of the KIEE Conference
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    • pp.676-678
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    • 2002
  • This paper deals with the design and characteristic analysis of a coreless an axial flux permanent magnet (AFPM) motor. Axial-flux permanent magnet motors prove to be the best candidate for application in electric vehicles (EVs) as direct-drive wheel motors, as in comparison with conventional motors they allow design with higher compactness, lightness and efficiency. Recently, issues regarding environment and the diversification of dependence in oil are watched with keen interest. In this theses, through the simulation of AFPM for low and high torque which has stator in the center and two rotors each side, understand its specialty, with this, make a prototype motor and design drive which can enhance the motors stability in low speed. Especially, specialty of motors torque power output will be mainly talked and based on this, possibility of application in EVs will be inspected by the theoretical study and the test.

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Electromagnetic field analysis and performance characteristics of PMSM/G with Halbach magnetized array rotor (Halbach 자화 배열 회전자를 갖는 영구자석 동기 전동발전기의 전자기적 해석 및 성능 특성)

  • Jang, Seok-Myeong;You, Dae-Joon;Ko, Kyoung-Jin;Choi, Sang-Kyu
    • Proceedings of the KIEE Conference
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    • pp.86-88
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    • 2008
  • The rotational loss is one of the most important problems for the practical use of the high power Flywheel Energy Storage System (FESS). This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized any and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the high power FESS.

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