International Journal of Applied Electromagnetics and Mechanics - Volume 52, issue 1-2

Authors: Nishiura, Yusuke | Hirata, Katsuhiro | Sakaidani, Yo | Niguchi, Noboru

Article Type: Research Article

Abstract: The development of multi degree-of-freedom actuating systems has been required in robotics and industrial machinery fields. In general, however, the actuating system with several degrees of freedom is composed of some single degree-of-freedom motors, which results in large, heavy and complicated structures. Therefore, multi-degree-of-freedom actuators are expected to become a key technology to solve these problems and many types of actuators have been studied. We have been developing a 3-DOF spherical actuator which can rotate around multi axes. In this paper, to improve controllability, a new compensation method which cancels out the cogging torque is proposed and the effectiveness of …the control method is verified through 3D-FEM and measurements using a prototype. Show more

Keywords: Spherical actuator, 3-DOF, cogging torque, position control

DOI: 10.3233/JAE-162029

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 579-589, 2016

Authors: Yoon, Keun-Young | Lee, Jin-Hee | Kwon, Byung-Il

Article Type: Research Article

Abstract: This paper proposes a new design of interior permanent magnet (IPM) type brushless DC (BLDC) motor using low-price ferrite magnet which has the similar characteristics as the IPM type BLDC motor that uses expensive NdFeB magnet. In order to replace the NdFeB magnet, the proposed design adopts the structure of the C-shape permanent magnets which are arranged as the flared shape. The characteristics of the proposed IPM motor are compared with the NdFeB IPM motor through the finite element analysis (FEA). It is demonstrated that proposed model satisfied with the characteristics of the NdFeB IPM motor.

Keywords: IPM BLDC, permanent magnet, ferrite magnet, flared-shape arrangement, flared, c-type magnet, nodal force, torque ripple, concentrated winding, compressor

DOI: 10.3233/JAE-162059

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 591-597, 2016

Authors: Zhao, Wenliang | Kwon, Byung-Il

Article Type: Research Article

Abstract: This paper proposes a novel dual rotor radial field flux switching permanent magnet machine (FSPMM) with phase-group concentrated-coil (PGCC) windings and two misaligned rotors to obtain high performance, including high torque density and low cogging torque, as well as low torque ripple. The proposed FSPMM features a new combination of stator slots and rotor poles, which is determined by the winding configurations. The PGCC windings are adopted to obtain a unity displacement winding factor, and enhance the flux focusing effects together with the use of spoke-type PM constructions. The unaligned arrangement of two rotors will help to not only achieve …further flux magnification by an alternate operating principle for PM flux concentration, but also suppress the cogging torque. To highlight the advantages of the proposed FSPMM, two conventional FSPMMs with typical machine configurations having concentrated windings are adopted for performance comparison based on a finite element method (FEM) using JMAG-Designer. Show more

Keywords: Cogging torque, dual rotor, finite element method, flux switching permanent magnet machine, phase-group concentrated-coil windings, torque density, torque ripple

DOI: 10.3233/JAE-162068

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 599-607, 2016

Authors: Watanabe, Yuta | Igarashi, Hajime

Article Type: Research Article

Abstract: This paper discusses the shape optimization of chipless radio frequency identification (RFID) tags comprising fractal structures. In the proposed optimization process, scattering electromagnetic waves from a chipless RFID tag are analyzed using a finite-difference time-domain (FDTD) method. The shapes of the chipless RFID tags are optimized by a micro-genetic algorithm (m-GA) to determine the frequencies of the subject scattering waves, as well as to maximize their associated amplitudes and quality factors. As such, a self-similar metal line and metal patch comprising fractal structures are assumed to be a chipless RFID tag. The optimized tags obtained using the FDTD method and …m-GA ultimately maintain the selective frequencies, high amplitudes, and quality factors of the scattering electromagnetic waves. Show more

Keywords: Chipless RFID, shape optimization, m-GA, FDTD method

DOI: 10.3233/JAE-162062

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 609-616, 2016

Authors: Sakata, Yuki | Washio, Naoya | Mifune, Takeshi | Matsuo, Tetsuji

Article Type: Research Article

Abstract: This study proposes an efficient method of local space-time grid refinement and examines the numerical stability and the accuracy of electromagnetic field analysis using the space-time finite-integration technique (FIT). The proposed subgrid method locally refines the space-time grid with three-division or four-division and is stable without inducing numerical instability even after one million time-steps. The grid construction is modified at the corner part of subgrid connection to improve the computational accuracy. The staircase-type grid relaxes the time-step restriction due to the CFL condition.

Keywords: Finite integration technique, space-time grid, multiple-division, subgrid

DOI: 10.3233/JAE-162053

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 617-622, 2016

Authors: Itoh, Keiichi | Watanabe, Kento | Miyata, Katsumasa | Igarashi, Hajime

Article Type: Research Article

Abstract: This paper reports the performance improvement of the planar waveguide slot array antenna by loading the small spherical dielectric lenses. The proposed lens is sphere and small, and can be loaded on each slot independently. To design the antenna with the proposed lenses, other design parameters are fixed, and the optimal slot length is searched by using the finite difference time domain (FDTD) method. From both the calculated and the measured far-field radiation patterns, the optimized antenna with the proposed lenses shows good performance as the resonant uniformly distribution array. By comparing with the conventional antenna, it is found that …the gain increase by loading small lens is estimated by 1.07 dB. Show more

Keywords: Dielectric lens, planar array antenna, FDTD method, waveguide slot antenna

DOI: 10.3233/JAE-162047

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 623-630, 2016

Authors: Mori, Takuya | Igarashi, Hajime

Article Type: Research Article

Abstract: This paper presents optimal shape design of planar array antennas for microwave energy harvesters. The topology optimization of the C4 -symmetric array antenna is conducted to maximize their isotropic gain and minimize the return losses in a frequency band ranging from 1.5 to 3.5 GHz. Then, we design the rectifier by varying the circuit parameter based on measurement results to realize the impedance matching between the optimized antenna and rectifier. It is shown by experiment that the harvester composed of the optimized array antenna and rectifier has higher receiving voltage in comparison with the single one. Moreover, the resultant harvester …is found to start operating when the arrival electric field is greater than 0.1 V/m. Show more

Keywords: Microwave energy harvester, wideband antenna, topology optimization, array antenna

DOI: 10.3233/JAE-162057

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 631-639, 2016

Authors: Pereira, Jorge | Matos, Verónica

Article Type: Research Article

Abstract: Resonant Cavity Enhanced (RCE) photodiodes may have advantages over the conventional p-i-n photodiodes due to an enhancement of the quantum efficiency obtained from the constructive interference of the light waves that are made to oscillate in a cavity. In this paper a novel RCE structure, with applications in long wavelength optical communication systems, is proposed and its frequency response is investigated and compared to that obtained for conventional p-i-n devices. An optimization procedure is implemented and the results show that these RCE photodetectors may have bandwidths larger than 80 GHz and a bandwidth-quantum efficiency product above 80%.

Keywords: RCE photodiodes, frequency response, modelling, p-i-n photodiode

DOI: 10.3233/JAE-162075

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 641-648, 2016

Authors: Sato, Yuki | Mori, Takuya | Shimotani, Toshihito | Igarashi, Hajime

Article Type: Research Article

Abstract: It is known that the proper orthogonal decomposition (POD), which is one of the effective approaches for model order reduction (MOR), can effectively reduce computational time for finite element method (FEM). This paper proposes a new method for generation of equivalent circuits based on POD-based FEM. In this method, the circuit parameters are determined by genetic algorithm so that the input impedance of the equivalent circuit is coincident with that computed by POD-based finite element method (FEM). For test of the proposed method, POD-based FEM is applied to analysis of a dipole antenna which is loaded with the Cockcroft Walton …circuit. It is shown that this method can reduce the computational time to generate the equivalent circuit without deterioration of accuracy. Show more

Keywords: Model order reduction, antenna analysis, proper orthogonal decomposition, equivalent circuit

DOI: 10.3233/JAE-162061

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 649-657, 2016

Authors: Mihalache, Ovidiu | Yamaguchi, Toshihiko | Shirahama, Takuma | Ueda, Masashi

Article Type: Research Article

Abstract: The paper presents investigation of dynamical window multi-frequency (DWMF) eddy currents algorithm applied to the helical steam generator tubes of FBR to improve the defect detection when the defect is free of sodium or sodium partially fills the volume of the defect. The task is accomplished using large scale three dimensional (3D) finite element (FE) numerical simulations, based on an in-house developed code massive parallelized, that can take into account full circumferential and partial outer tube defects located near or far from the tube support plate.

Keywords: Eddy currents, 3D, finite element, FBR, steam generator, multi-frequency, sodium

DOI: 10.3233/JAE-162032

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 659-666, 2016