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Article
Publication date: 9 September 2013

Norio Takahashi, Kousuke Shimomura, Daisuke Miyagi and Hiroyuki Kaimori

– The purpose of this paper is to propose the speed-up of the fixed-point method by updating the reluctivity at each iteration (this is called a modified fixed-point method).

Abstract

Purpose

The purpose of this paper is to propose the speed-up of the fixed-point method by updating the reluctivity at each iteration (this is called a modified fixed-point method).

Design/methodology/approach

A modified fixed-point method, which updates the derivative of reluctivity at each iteration, is proposed. It is shown that the formulation of the fixed-point method using the derivative of reluctivity is almost the same as that of the Newton-Raphson method. The convergence characteristic of the newly proposed fixed-point method is compared with those of the Newton-Raphson method.

Findings

The modified fixed-point method has an advantage that the programming is easy and it has a similar convergence property to the Newton-Raphson method for an isotropic nonlinear problem.

Originality/value

This paper presents the formulation and convergence characteristic of the modified fixed-point method are almost the same as those of the Newton-Raphson method.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 15 November 2011

Norio Takahashi, Hirofumi Shinagawa, Daisuke Miyagi and Yuhito Doi

The purpose of this paper is to examine the mechanism of the increase or decrease of eddy current loss of the segmented Nd‐Fe‐B sintered magnets without insulation, and…

Abstract

Purpose

The purpose of this paper is to examine the mechanism of the increase or decrease of eddy current loss of the segmented Nd‐Fe‐B sintered magnets without insulation, and the effects of parameters on such a phenomenon are discussed.

Design/methodology/approach

The measured contact resistance is used in the finite element analysis.

Findings

It is shown that the eddy current loss in a magnet shows the peak value when the number of segments are increased at 40 kHz, but this property is changed at low frequency (10 kHz). Its tendency is changed by the contact resistance and the permeance (surrounding iron core).

Originality/value

The reason of a curious property of eddy current loss of segmented magnets is clearly explained by examining the eddy current distribution at various contact resistances.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 2014

Norio Takahashi, Akira Akagi, Masanori Nakano, Yuhito Doi and Daisuke Miyagi

In the laminated core of transformer, motor, etc. each electrical steel sheet is usually insulated in order to reduce the eddy current loss. Raw steel sheets without…

Abstract

Purpose

In the laminated core of transformer, motor, etc. each electrical steel sheet is usually insulated in order to reduce the eddy current loss. Raw steel sheets without insulation are sometimes used in a small core of electrical machines and electronic equipments, because the cost of iron core can be reduced if cheap steel sheets without insulation are used in the core. The purpose of the paper is to show how the contact resistance between sheets of laminated core affects the interlaminar eddy current and to show the criterion for judgment of the necessity of insulation.

Design/methodology/approach

The eddy current losses of core made of SPCC (cold rolled steel sheets) of different widths with and without insulation under various conditions are analyzed by using the finite element method (FEM) considering the contact resistance. The equivalent circuit for such a laminated core without insulation is shown. The experimental investigation is also carried out.

Findings

A criterion for the judgment of insulation is examined. It is shown that the increase of eddy current is affected by the ratio (this corresponds to the criterion) of the resistance of steel and the contact resistance.

Originality/value

The paper clarifies a criterion for the necessity of insulation between sheets of laminated core. It is shown that a similar tendency to the measured value of eddy current loss can be obtained by utilizing the modeling method of laminated core.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 December 2004

Yoshifumi Okamoto, Toshio Imai, Daisuke Miyagi, Norio Takahashi, Kazuhiro Ozaki, Hiroshi Ono and Naoki Uchida

Induction heating is widely used in the industry due to high efficiency, precise control, rapid heating and low pollution properties. To process a semiconductor of high…

Abstract

Induction heating is widely used in the industry due to high efficiency, precise control, rapid heating and low pollution properties. To process a semiconductor of high quality, uniform heating is necessary, but it is not easy to heat uniformly by using the conventional induction heating equipment. For this purpose, the zone control induction heating equipment is jointly developed with Mitsui Engineering Shipbuilding Co., Ltd. In this paper, the optimization of current in each coil is carried out using the finite element method and the optimization method in order to obtain a uniform eddy current loss distribution on graphite.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 13 March 2007

Daisuke Chugo, Kuniaki Kawabata, Hiroyuki Okamoto, Hayato Kaetsu, Hajime Asama, Norihisa Miyake and Kazuhiro Kosuge

The aim is to develop a force assistance system for standing‐up which prevents the decreasing of physical strength of the patient by using their remaining physical strength.

Abstract

Purpose

The aim is to develop a force assistance system for standing‐up which prevents the decreasing of physical strength of the patient by using their remaining physical strength.

Design/methodology/approach

The system realizes the standing up motion using the support bar with two degrees of freedom and the bed system which can move up and down. For using the remaining physical strength, our system uses the motion pattern which is based on the typical standing up motion by nursing specialist as control reference.

Findings

The assistance system realizes the natural standing up motion by nursing specialist and it is effective to assist the aged person to stand up without reducing their muscular strength.

Originality/value

The first idea is distributed system which controls the support bar and the bed system with coordination among them. The second idea is the combination of force and position control.

Details

Industrial Robot: An International Journal, vol. 34 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

Abstract

Details

Construction Industry Advance and Change: Progress in Eight Asian Economies Since 1995
Type: Book
ISBN: 978-1-80043-504-9

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