International Journal of Applied Electromagnetics and Mechanics - Volume 59, issue 2

Authors: Maruo, Akito | Igarashi, Hajime

Article Type: Research Article

Abstract: The chaotic vibration energy harvester (CVEH) converts vibration of constructions to electric energy in wide frequency. It needs large computational cost for evaluation of the magnetic force between the moving magnets and magnetic material embedded in the stator coils of CVEH when using finite element method (FEM). This paper presents magnetic circuit modeling of CVEH to reduce computational burden. It is shown that the frequency responses of CVEH computed by the present method is in good agreement with those obtained by FEM. This result is validated through the experiment.

Keywords: Vibration energy harvester, magnetic circuit, chaotic oscillation, genetic algorithm

DOI: 10.3233/JAE-171248

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 567-575, 2019

Authors: Wei, Wei | Sun, Feng | Jin, Jiaqi | Zhao, Zhiyu | Miao, Liguo | Li, Qiang | Zhang, Xiaoyou

Article Type: Research Article

Abstract: Energy-recycle type active suspension (ETAS) using magnetic force has been proposed and modified by MacPherson suspension, with the purpose to decrease the vibration of vehicle suspensions and recycle the energy generated by shock absorbers. This paper proposes a new type voice coil motor (VCM) embedded in the conventional shock absorber and realized its functions with two working modes. Based on the ETAS, magnetic field distribution in air gap of the VCM is analyzed by theoretical model and finite element method (FEM) analysis, which validates the accuracy of the theoretical model and preliminary optimization. Then, dynamic models of the 1/4 ETAS …with two working modes are established to certificate the impact of the two modes during the vehicles operation. Finally, energy consumption and recycle are respectively simulated under the standard C-level road surface, which investigates the efficiency of the ETAS system. The simulation results show that average powers of energy consumption and energy recycle are 9.29 W and 1.81 W, the efficiency of the ETAS system is 19.5%. Show more

Keywords: Active suspension, magnetic force, energy recycle, active control

DOI: 10.3233/JAE-171085

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 577-585, 2019

Authors: Parekh, Mrunal | Bissal, Ara | Magnusson, Jesper | Engdahl, Göran

Article Type: Research Article

Abstract: Ultra-fast circuit breakers are operated with fast electromagnetic actuators. They can generate a sufficient impulse force to swiftly open electrical contacts in a couple of milliseconds. Opening of the contacts with high velocities implies a need for a timely and controllable damping. An efficient damping mechanism then is crucial to attain an appropriate actuation performance and secure a long lifetime. In this paper a finite element model of a Halbach magnet array based magnetic damper and a corresponding experimental prototype is described. A parametric study is performed to understand the effect of load mass and incoming velocities. It was found …that the magnetic field modulation plays an important role on the damping performance. A uniform and high radial component of the magnetic flux density is necessary in order to achieve high damping force. The radial magnetic field can be controlled via thickness and magnetization direction of the ring magnets that are used to create the Halbach magnet array. Show more

Keywords: Halbach magnet array, magnetic damper, permanent magnet, FEM (finite element method), circuit breaker, radial component of magnetic flux density

DOI: 10.3233/JAE-171039

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 587-595, 2019

Authors: Xu, Binbin | Yan, Bo | Ma, Chicheng | Zhang, Xinong

Article Type: Research Article

Abstract: The variation of electrical parameters will inevitably influence the performance of electromagnetic shunt damping. To overcome this, this paper presents an adaptive negative resistance shunt to improve the vibration control performance. A novel electromagnetic isolator is designed, modelled and fabricated. The electromagnetic coupling coefficient is obtained according to the current model, and the corresponding parameters are optimized numerically and verified experimentally. An adaptive negative resistance shunt circuit is constructed. The results show that the proposed adaptive negative resistance shunt can adjust resistance to an optimal value and thus improve the vibration isolation performance of the electromagnetic isolator.

Keywords: Shunt damping, adaptive negative resistance, electromagnetic isolator

DOI: 10.3233/JAE-171077

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 597-606, 2019

Authors: Sun, Feng | Zhou, Ran | Jin, Junjie | Li, Qiang | Xu, Fangchao | Sun, Xingwei | Oka, Koichi

Article Type: Research Article

Abstract: A proposed permanent magnetic suspension using flux path control has quasi-zero power characteristic since its unique structure realizes transmitting the suspended object’s gravity the system frame, and the motor just drives the permanent magnet to rotate and suffers a small regular torque caused of the system magnetic potential. The small regular torque will deteriorate the system’s response characteristics and suspension stability. This paper optimizes the system structure for improving the quasi-zero power characteristic. Firstly, the structure and the suspension principle of the former system is introduced, and the rotational torque on the motor’s shaft was measured using an experimental prototype. …Secondly, a symmetric offset optimal structure was proposed through analyzing the experimental results of rotational torque, and the torque on the motor’s shaft was calculated by using a FEM model. The simulation results indicate that the rotational torque was reduced to about 15% of the former structure using the optimized structure with a magnetic separation iron plate. Finally, the experimental prototype with the optimized structure was manufactured, and the measurement experiment for the torque was carried out. The experiment results verified the validity of the simulation results and the optimizations. Show more

Keywords: Permanent magnetic suspension, variable flux path control, zero power, optimization, finite element simulation

DOI: 10.3233/JAE-171203

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 607-616, 2019

Authors: Dong, Guangxu | Li, Qiang | Zhang, Xinong

Article Type: Research Article

Abstract: To suppress resonance and broaden the bandwidth for vibration absorption, a nonlinear dynamic vibration absorber (NDVA) with negative stiffness is developed in this paper. The magnetic negative stiffness spring (MNSS), the generation mechanism of negative stiffness, is composed of three magnet rings arranged in attraction, and employed to connect with mechanical spring in parallel. The magnetic force and its corresponding stiffness of the MNSS are investigated firstly. Attaching the NDVA to main mass, the dynamic equations of the coupled system is established, and the averaging method is also applied to the dynamic responses. With the aim of excellent vibration absorption …performance of the NDVA, an iterative algorithm is proposed to perform the parameter optimization with the purpose of avoiding time consumption. Finally, the results show that the optimization algorithm can significantly improve the efficiency of parameter selection for the NDVA, resulting in the remarkable vibration attenuation for primary system and a larger bandwidth for vibration absorption. Show more

Keywords: Nonlinear dynamic vibration absorber, negative stiffness, vibration absorption, optimization algorithm

DOI: 10.3233/JAE-171201

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 617-628, 2019

Authors: Chigira, Koji | Kurahashi, Takahito | Ando, Yoshinori | Murakami, Iwanori

Article Type: Research Article

Abstract: The authors have been studying the magnetic harmonic gear with the stackable structure. In this paper, we propose a new magnetic harmonic gear which has the stackable structure. This new magnetic gear is expected that a torque characteristics are improved. The maximum transmission torque is calculated by simulation. The torque characteristics of a proposed magnetic gear are compared with that of the past magnetic gear. As the result, the maximum transmission torque of a proposed type is improved approximately 5.96 times and the torque density is improved about 3.82 times.

Keywords: Magnetic gear, magnetic flux, magnetization direction

DOI: 10.3233/JAE-171194

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 629-637, 2019

Authors: Sekijima, Yuya | Ando, Yoshinori | Murakami, Iwanori

Article Type: Research Article

Abstract: Although the researches into increasing the transmission torque and the torque density of magnetic gears are performed, setting the torque to the required value after assembling is almost not done. In this study, we examined adjusting the step-out torque by inserting a plane rectangular coil between opposed magnetic gears. It is possible that the magnetic field generated from a coil decreases the step-out torque. Therefore, the relationship between the characteristic value of the coil and the transmission torque was investigated experimentally. The theoretical value of the transmission torque decrease rate by calculation and the experimental result are compared. When the …rotational frequency was less than 700 rpm, the transmission torque reduction rate by the coil was about the same as the calculated value, and adjusting the step-out torque by the coil is expected. Show more

Keywords: Magnetic gear, step-out torque, plane rectangular coil, torque control

DOI: 10.3233/JAE-171192

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 639-646, 2019

Authors: Guan, Honglu | Liu, Lei | Yang, Shiyou | Chen, Xiangrong

Article Type: Research Article

Abstract: Metamaterials have successfully been developed and applied in low frequency regime, showing that they have great potentials in engineering applications, especially the ones with a negative permeability are very promising in wireless power transfer (WPT). This paper proposes a methodology to increase the efficiency of a WPT system using both resonant coils and some negative permeability metamaterials. To achieve this goal, a negative permeability metamaterial unit is proposed and optimized. Moreover, an eventual optimization of the proposed system is also discussed. To validate the performances of the corresponding WPT system, the transfer efficiency is computed using a finite element method. …And an experiment prototype is constructed and tested to verify the accuracy of the simulated results. Show more

Keywords: Wireless power transfer, negative permeability, metamaterial

DOI: 10.3233/JAE-171183

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 647-655, 2019

Authors: Wang, Shuang | Wang, Shuhong | Li, Hailin | Yuan, Dongsheng

Article Type: Research Article

Abstract: The elastic characteristics of transformer winding materials have an important influence on its deformation due to short-circuit (SC) fault. This paper presents an electromagnetic-thermal-fluid-mechanical coupling analysis method for dynamic deformation calculation of power transformer windings under SC fault, considering the influence of temperature on modulus of elasticity of winding materials. The dependence of modulus of elasticity of spacer and copper conductor on temperature in transformer windings are tested by dynamic thermal mechanical analyzer. The transient dynamic response of windings deformation including mechanical stress and displacements, as well as temperature distribution, for an oil-immersed-type 110 kV power transformer due to SC are …obtained using the proposed method. The maximum stress and displacement achieved by the proposed method is greater than that calculated neglecting the temperature dependence of elasticity of modulus of winding materials. The upper part of the winding are more susceptible to damage due to SC impact. Show more

Keywords: Dynamic deformation, transformer windings, elasticity characteristics

DOI: 10.3233/JAE-171050

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 2, pp. 657-668, 2019