International Journal of Applied Electromagnetics and Mechanics - Volume 65, issue 3

Authors: Vučković, Ana N. | Vučković, Dušan M. | Perić, Mirjana T. | Raičević, Nebojša B.

Article Type: Research Article

Abstract: The aim of this paper is to emphasize the influence of the magnetization vector misalignment to the magnetic force. In this concrete example the force between permanent ring magnet and soft magnetic cylinder was analyzed. Configuration that can be seen in different devices that incorporate permanent magnets. Magnetic force between permanent ring magnet and soft magnetic cylinder is calculated using hybrid boundary element method and semi-analytical approach based on fictitious magnetization charges. By selecting the angle of the magnetization vector inclination, obtained expression can be used for the force calculation of axially or radially magnetized permanent magnet and magnetic …body of finite dimension. Show more

Keywords: Hybrid boundary element method (HBEM), magnetization charges, magnetic force, permanent ring magnet

DOI: 10.3233/JAE-190152

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 417-430, 2021

Authors: Li, Tao | Zhang, Youtong | Liang, Yuxiu | Yang, Ye | Jiao, Jie

Article Type: Research Article

Abstract: The yokeless and segmented armature axial-flux in-wheel motor with amorphous magnet metal (AMM) stator segment has the advantage of low iron losses, but its open-slot structure causes high eddy-current losses of the permanent magnet (PM), which reduces the efficiency and reliability of the in-wheel motor. To avoid the demagnetization caused by the heat generated by PM losses, the mechanism of PM eddy-current losses reduction for the axial-flux in-wheel motor is revealed by the calculation model. In this paper, the time-step three-dimensional finite-element method (3-D FEM) is used to analyze the PM eddy-current loss caused by slotting effects, spatial harmonics, and …time harmonics at different speeds. The effect of PM skewing, PM segmentation, and soft magnetic composite (SMC) layer inserted on the top of PM on eddy-current losses are compared. These methods cannot simultaneously meet the requirements of PM losses reduction and the electromagnetic performance of the motor. A novel combined stator segment with the SMC brim arranged on the top of the AMM stator teeth is proposed to improve the amplitude and distribution of the PM eddy-current density. The analysis results show that the combined stator segment can significantly reduce the PM eddy-current loss and improve the electromagnetic performance of the in-wheel motor. Show more

Keywords: Amorphous magnet metal, axial-flux machines, eddy-current losses reduction, in-wheel motors, yokeless and segmented armature

DOI: 10.3233/JAE-190129

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 431-450, 2021

Authors: Shan, Yi | Ai, Mengmeng | Liu, Wenhui

Article Type: Research Article

Abstract: The safety and reliable operation of power grid is directly related to the ability of power transformer to withstand short-circuit, therefore, it is a problem to be solved to improve the ability of large power transformer windings to withstand short-circuit. Taking a three-phase five-limb power transformer as an example, the transient electromagnetic field, short-circuit electrodynamics force of windings and mechanical strength of coils are analyzed in depth. Firstly, the three-dimensional finite element model of the prototype is established, and the magnetic flux density distribution of the three-dimensional transient electromagnetic field of transformer under short-circuit operation and the axial and radial …static force magnitude of the winding are calculated by using the field-circuit coupling method, and the distribution law can be obtained. At the same time, the mechanical strength of power transformer winding in its height direction is discussed, and the modal vibration mathematical model of transformer low-voltage winding in Z-axis direction is established. The displacement change and resonance frequency of the winding wire cake in the axial direction caused by short-circuit are calculated, and the short-circuit electrodynamics force of the winding is also checked. The research in this paper provides a theoretical basis for strengthening the design of short-circuit withstanding capacity of windings, and has a certain theoretical and engineering application value. Show more

Keywords: DC power transformer, field-circuit coupling, short-circuit electrodynamics force, winding mechanical strength

DOI: 10.3233/JAE-200021

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 451-465, 2021

Authors: Yu, Qiang | Zhuang, Haijun | Tian, Lisi

Article Type: Research Article

Abstract: Due to use of cans in the airgap, the eddy current induction occurs and generates can loss. The loss on cans is considerably high and leads to excessive temperature rise of a canned motor, a fast and accurate temperature is necessary. In this paper, a compensation element assisted thermal model is proposed and stressed, due to the inaccuracy of tradition thermal network model. First, the studied canned motor is described. Second, the thermal analysis principle is studied. Then, the novel thermal network model with compensation element is studied, with thermal resistance calculation. Finally, compare motor temperature that is measured by …thermal network model and finite element (FE). FE is used as reference and complement. Show more

Keywords: Thermal analysis, lumped parameter thermal network, compensation elements, canned permanent magnet machine, can loss

DOI: 10.3233/JAE-200020

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 467-485, 2021

Authors: Yazdanpanah, Reza | Farjah, Ebrahim

Article Type: Research Article

Abstract: This paper presents the cogging torque calculation in radial-flux surface-mounted permanent-magnet machines based on energy approach, air-gap flux density and permeance functions. Magnet segmentation and teeth notching are two important techniques in reducing the cogging torque, so in this paper an analytical approach is investigated to model these effects on the produced cogging torque. This approach employs new methods to model the teeth notch and PM segments based on Fourier expansion and simplified flux distribution. The analysis results and comparisons verify the validity of the model that has advantages in sensitivity analysis and structure optimizations of surface-mounted permanent-magnet machines from …the aspect of cogging torque. This model could be extended for other types of PM electrical machines. Show more

Keywords: Analytical, cogging torque, notch, PM machine, segmented PM

DOI: 10.3233/JAE-190162

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 487-500, 2021

Authors: Zhao, Yang | Li, Yong | Shen, Yunde

Article Type: Research Article

Abstract: This letter presents a bistable permanent magnet actuator, based on double wing magnetic flux (DWMF) formed by the structure of welding sleeve and slotted armature. The double wing magnetic flux consist of high wing magnetic flux (HWMF) and low wing magnetic flux (LWMF), resulting in bistable performance under differentiating control. Parameters improvement around DWMF is analyzed based on modeling, and optimized results for a prototype actuator are obtained. The experimental and simulation results agree well, and show that the prototype actuator can realize bistable performance under the DC step voltage drive, with the holding force of 8.2 N (without current) …and the restoring force of −31.7 N (with negative current), the dynamic results show that the displacement response time within 8 mm is 28 ms, of which the actuation time is 16.5 ms, the transient maximum power consumption of the restoring period is 18 W. Show more

Keywords: Bistable, double wing magnetic flux, permanent magnet, welding sleeve, slotted armature

DOI: 10.3233/JAE-190119

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 501-512, 2021

Authors: Borges, José William Ribeiro | Fonseca, Wellington da Silva | Brasil, Fernando de Souza | Araújo, Ramon C.F.

Article Type: Research Article

Abstract: The electrical insulation is one of the main sources of failures in hydro-generators, therefore it is important to research the insulation system of stator bars. In this paper, it is developed a steady-state multiphysics analysis of a stator bar using the Finite Element Method to assess its steady-state behavior in the electrical, magnetic and thermal domains. Different aspects are analyzed in simulations, such as capacitance, mechanical stress and thermal effects. Numerical results are compared with experimental measurements for validation.

Keywords: Stator bar, finite element method, multiphysics analysis, hydro-generator

DOI: 10.3233/JAE-200012

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 513-526, 2021

Authors: Liu, Chuan | Chen, Renwen | Zhang, Yuxiang | Liu, Wen | Wang, Liping | Qin, Jinchang

Article Type: Research Article

Abstract: As a renewable energy, ocean wave energy is exploited with infinite potential to solve the energy crisis. In this study, we develop a novel two-body direct-drive wave energy converter (DD-WEC) to surmount the problems associated with low power density, low direct-drive speed of the buoys, seawater corrosion and maintenance in the existing two-body WEC. Its prototype consists of two cylindrical buoys that float horizontally at sea level and the Halbach permanent magnet linear generator (HPMLG) that is employed in the power take-off (PTO) system. The energy is extracted from the relative motion between two buoys oscillating. Compared with the existing …WEC, the proposed WEC has more vigorous motion between buoys, higher conversion efficiency and little extra underwater structure, due to the utilization of the horizontal buoys and the HPMLG. First, the motion equations of buoys are derived on the basis of linear wave theory. And depending on the motion equations, the structure of buoys and the HPMLG is designed. And we found that compared with the existing WEC, the proposed WEC has more vigorous motion between buoys in the seawater waves oscillation. Then, based on finite-element method (FEM), the performance of the HPMLG is evaluated, and it can generate 19% more power than the traditional permanent magnet linear generator (TPMLG) based on the same wave motion. Finally, the DD-WEC prototype is manufactured based on the designed parameter. The manufactured prototype is tested in the test platform and the wave tank. The measured output voltage is highly consistent with the observed variation trends in FEM simulation data. The results show that the proposed DD-WEC is well suited for wave energy conversion. Show more

Keywords: DD-WEC, HPMLG, two cylindrical buoys, motion equations of the buoys, performance analysis

DOI: 10.3233/JAE-201500

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 527-544, 2021

Authors: Seebacher, Philipp | Kaltenbacher, Manfred | Wein, Fabian | Lehmann, Henry

Article Type: Research Article

Abstract: A pseudo density topology optimization approach is introduced in nonlinear electromagnetism, which follows the SIMP (Solid Isotropic Material with Penalization) method. The adjoint approach is used to arrive at the sensitivity of the objective function. The elaborated optimization procedure includes nonlinearity of the ferromagnetic material. On the other hand, an applied linear characteristic of the ferromagnetic material results in a too small or wrong electromagnetic actuator dimension. Non-conforming grids are used to achieve a high accuracy by computing the discrete form. At the same time the number of finite elements decreases strongly. The implementation is applied to an electromagnetic actuator …in 2D and 3D. Show more

Keywords: Topology optimization, adjoint method, nonlinear magnetostatics, SIMP, non-conforming grids

DOI: 10.3233/JAE-201501

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 545-559, 2021

Authors: Wang, Zihui | He, Zhiyuan | Cai, Jiongjiong

Article Type: Research Article

Abstract: In electric motorcycles and light electric cars, permanent magnetic synchronous motor (PMSM) of outer-rotor type are preferred, due to its concise structure and flexible control. Since the body mass and road impact causes vertical eccentricity on shaft bearings, vibration and noise take place during vehicle cruising along with a torque and speed ripple. The torque ripples contain significant features closely related to eccentricity, and those special components can be compensated by an injection current with proper frequency, phase and amplitude. In this paper, a novel control method is used to regulate the injection current to restrain torque ripples. By coarse …turning with quadratic spline curve fitting and fine turning with successive approximation, the method can response sudden disturbance and drive the specific torque ripple to minimum in a very short time, so that the performance on ride comfort and handling stability of the vehicle could be improved. Experimental tests show that the method performs favorably with rapid convergence and validity. Show more

Keywords: Electric vehicle (EV), in-wheel motor (IWM), rotor eccentricity, minimum amplitude point tracking, quadratic spline curve fitting

DOI: 10.3233/JAE-201503

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 3, pp. 561-577, 2021