The Asia Pacific Symposium of Applied Electromagnetics and Mechanics 2012 (APSAEM 2012) is the seventh symposium devoted to topics on electromagnetic phenomena, both on low and high frequencies, and its applications in electrical, mechanical, and communication systems. It was first started in 2000 at Adelaide, Australia and then at Kanazawa, Japan in 2001, followed with Auckland, New Zealand (2004), Sydney, Australia (2006), Bangkok, Thailand (2008), Kuala Lumpur, Malaysia (2010). The symposium is one in a series of events sponsored by the Japanese Society of Applied Electromagnetics and Mechanics (JSAEM).
APSAEM 2012 is organized by the HoChiMinh City University of Technology (HCMUT) and Faculty of Electrical- Electronics Engineering (FEEE) and co-organized by the Japanese Society of Applied Electromagnetics and Mechanics (JSAEM), Shinshu University and Kanazawa University, Japan from July 25 to July 26-2012. The symposium provides an excellent biennial symposium for sharing knowledge, experience and creative ideas among academia from various universities, research institutes, as well as from industries in the area of applied electromagnetic and mechanics, such as the following: Computational electromagnetics, Inverse problems, Characterization and modeling of electromagnetic materials, Magnetic sensors and measurement, Nondestructive testing, Applications of electromagnetic phenomena, MEMS, Electromagnetic and electromechanical devices and systems, Electromagnetic actuator and applications of permanent magnet, Applications in power, electronics, and control systems, Power electronics and drive systems, Electromagnetic environment and control, Electromagnetic compatibility (EMC), Applications of electromagnetic to medical treatments, Microwaves and antennas, terahertz applications, Applications in telecommunication, Electromagnetics and electromechanical education.
It is really a remarkable milestone to host the APSAEM 2012 held on the two days of July 25-26, 2012 in HoChiMinh City-VietNam, as the HoChiMinh City University of Technology and Faculty of Electrical- Electronics Engineering celebrate their 55 th anniversary on Oct 27th, 2012.
APSAEM 2012 has received more than 75 papers from international and local participants from 11 Asia Pacific and European countries and assembled authoritative keynote speeches, technical presentations, timely technical sessions, as well as exciting discussions among participants from universities, research institutes and industries for their further collaborations in the future.
The next eighth symposium will take place in Taichung in 2014.

View full abstract

In this paper we will discuss about the development of IE4 level motor proposed by IEC, which is new target for international efficiencies. Efficiency classes IE1-IE4 are defined in international standard IEC 60034-30. The draft version of IEC 60034-31 defines the new class IE4. The IE-codes replaces the former voluntary Eff classification of electric motors as shown in Table 1. The Eff classes are based on a voluntary agreement between the EU and the CEMEP in 1998.r.
Table 1 Minimum energy performance standards for electric motors.

View full abstract

In this paper, the usefulness of the three-dimensional finite element method with prismatic edge elements for the electromagnetic field analysis of a separate-type transformer with a thin core is clarified. The effects of the core division on the efficiency are clarified quantitatively. As a result, using prismatic edge elements, the eddy current can be calculated correctly even if there are the thin elements. In addition, the calculated current is almost the same as the measured one. The eddy current loss becomes smaller as the number of the core divisions increases.

View full abstract

To date, a vast majority of near-field magnetic induction applications tend to largely support uni- or bi-directional planar movement of loads. This is due to a lack of omni-directional magnetic field distribution provided by the electromagnetic structures. This paper demonstrates the concept of an omni-directional near-field wireless power transfer source capable of supporting three-dimensional load displacements. This is done by developing customized electromagnetic structures assisted by modern finite element method analysis computation software. In particular, two models are developed for investigation into both continuous and discontinuous modes of operation. The magnetic frequency response was simulated at an AC frequency of 155kHz. From analysis of the fundamental parameter governing performance metrics, the magnetic flux density, was tailored to support load displacement along three orthogonal axes. The resulting magnetic structures are intended for use as a loosely coupled near-field inductively-coupled-power-transfer system.

View full abstract

Giant magnetostrictive actuator has potential for producing a huge stress and minute stroke unlike electromagnetic actuators using electromagnetic force. We proposed the powerful generation of cavitation in water medium driven by the actuator. The collapse of cavitation generates pulse shock wave and also brings about radicals generating by addition of titanium oxide. The previous researches show the generation of cavitation and radicals based on the methylene blue test method, and the destructive influence of both virus and bacteria was recognized. The paper proposes a new apparatus of a circulation type system to aim the large capacity, and discusses the evaluation of sterilization and inactivation quantitatively. And we observed the biological condition of the cell to check the biological effect after sterilization.

View full abstract

Eddy current testing (ECT) is one of the most representative nondestructive testing methods for metallic materials, parts, structures and so on. Operating principle of ECT is based on the two major properties of magnetic field. One is that alternating magnetic field induces eddy current in all of the conducting materials. Thereby, an input impedance of the magnetic field source, i.e., electric source, depends on the eddy current path. Second is that the magnetic field distribution depends only on the exciting but also the reactive magnetic fields caused by the eddy currents in targets. Former and latter are the impedance sensing and magnetic flux sensing types, respectively.
This paper concerns with an improvement of sensibility of the impedance sensing method. Sensibility of the ECT is improved by means of two steps. One is an optimum exciting frequency selection. We employ the natural parallel resonant frequency of ECT coil. The other is to increase the sharpness of the resonance curve on impedance versus frequency characteristic by changing the coil connection. As a result, we have succeeded in developing the ECT sensor having up to 4 times higher sensibility compared with those of conventional one.

View full abstract

Contactless power supplier is composed of a transformer having the distinct primary and secondary coils separated by air gap. Because of the electromagnetic compatibility problem, it is essential to keep the leakage magnetic fields around the contactless power supplier as low as possible.
This paper carries out the wavelets multi-resolution analysis to the magnetic field distributions around contact- less power supplier. As a result, we have succeeded in obtaining one of the reasonable core shapes by observing the wavelets spectra of measured magnetic field vector distributions. Furthermore, it is revealed that a tested trial transformer gives nearly 80 percent power transmission efficiency even though the primary and secondary coils are separated by 10mm air gap.

View full abstract

This paper presents a new controller design method using the coefficient diagram method (CDM) for matrix converters (MCs). MCs are able to convert AC to AC power directly without DC link capacitors. In this paper MCs are used in unified power flow controllers (UPFCs), which is one of the flexible AC transmission system (FACTS) devices located in the transmission line. The CDM is an effective method for designing adequate gains in a PID controller but is not convenient for solving the complex characteristic polynomials of non-standard systems such as the multiplication of controller gains or multi-input-multi-output systems. We propose to combine CDMs with Particle Swarm Optimization (PSO). PSO is employed for searching the near optimal diagram. Our proposed method is applied to a simple transmission line and the validity of the proposed method is shown using MATLAB/Simulink simulation.

View full abstract

This paper describes a new mesh modification method for the three-dimensional finite element method, which prevents the mesh being broken to achieve the movement of the armature with long stroke. The effectiveness of this method is clarified through the dynamic characteristics analysis of a latch-in relay.

View full abstract

In our previous report, we proposed a magnetic shielding system for the calibration of high-sensitivity magnetometers. This system consists of inner hexagonal tubes and an outer cylinder. The hexagonal tubes have a double-layered structure, an opening and an advantage in axial shielding performance. The cylinder has openings and an advantage in transverse shielding performance. Compared with conventional cylindrical shields, our system is not capable of equipping a toroidally wound coil which can be used for degaussing the magnetic layers. The purpose of this paper is to reduce the residual magnetic flux density with a degaussing coil. Instead of the outer cylinder, we design an outer hexagonal tube. A solenoid-like coil is installed between the inner and outer tubes to effectively provide a degaussing field to the magnetic materials. For practical use, we also take care of both the total weight and shielding performance.

View full abstract

Miniaturization of electronic devices has making progress, resulting in smaller current flowing in extremely high-density LSI (large scale integration) or PCB (printed circuit board). However, measurements of such low local current have still been confronted with many difficulties because of the limitation on size of relatively large and cumbersome typical current sensors, lead to detecting general signals of a wide area. In this research, we propose the novel micron size and high sensitivity needle-type GMR probe in applications of non-contact measuring low currents coming from area narrower than 10^-6 m² with small signal crosstalk such as PCB current measurement and low bio magnetic signal detection. Low current of hundreds μA in high-density PCB tracks of 4×10^-4 m pitch was measured with the signal crosstalk less than 10% and 5×10^-6 A of nerve signal model was possible to be detected by micron size GMR probe.

View full abstract

The introduction of the oscillatory torque inside the reluctance machine during its operation with the reduction the air-gap length is a major tumble it as a high torque density machine. A double rotor structure that embeds the dual air gap structure to maximize the flux linkage and thereby the torque generating capability is proposed. For efficient operation the machine needs to operate close to saturation, and hence the estimation of magnetic and mechanical parameters is extremely cumbersome. Electromagnetic analysis of different positions on the machine to develop the flux linkage characteristics of the double rotor structure is presented. Pertaining equations of calculations for the magnetic components of the full overlap, partial overlap and full non-overlap positions are presented. A flux tube approach using integration technique is used for the analytical computations. The mechanical torque characteristics obtained from this analytical computation method is compared with that of the finite element analysis. The proposed technique of electromagnetic analysis can be applied to any type of electrical machine.

View full abstract

A QMG coil magnet is an application of an oxide bulk high T_c superconductor (HTS) to obtain high magnetic field. The QMG coil with 11 turns is made from a slice of Ag doped Gd-Ba-Cu-O QMG by using precise machining techniques by Nippon Steel Corporation. The magnet is made from 8 layers of the QMG coil and pulsed current is applied in experiments. Loss of the QMG coil magnet is numerically analyzed with an axisymmetric model, and the total loss of one coil is evaluated and discussed during magnetizing and demagnetizing processes.

View full abstract

This paper describes the resonance characteristics of two types of commonly-used electric power steering motors: the 8-pole-12-slot and the 10-pole-12-slot motor. The relationship between the excitation modes and characteristic vibrational modes is clarified by conducting a coupled magnetic field - structural analysis and carrying out a modal analysis on a prototype. Finally, the 8-pole-12-slot and 10-pole-12-slot motors are compared in terms of their generated noise.

View full abstract

This paper proposes an electromagnetic actuator for a prosthetic knee joint, which mainly consists of a ball screw and brushless motor. Energy consumption can be reduced by using the regenerated energy in the stance phase during the swing phase. The operational principle is described and the required torque-speed curve (N-T curve) is calculated by using the inverse kinematics. Then, a brushless motor that satisfies the required N-T curve is designed. Finally, the N-T curve of the brushless motor is computed by using a coupled magnetic field - electrical circuit - control analysis.

View full abstract

Nowadays, Linear Oscillatory Actuators (LOAs) are being used as vibration control devices. Electromagnetic LOAs are more effective as vibration control devices because of its high controllability. However, the thrust constant of the electromagnetic LOA is comparatively low and thus the electric power necessary to control the vibration is high. In this paper, we propose an LOA that uses regenerative energy and has a high thrust constant at certain frequencies.

View full abstract

In this paper, a novel forward adaptive neural MIMO NARX model is used for modelling and identifying the forward kinematics of the biped robot's 3-DOF arm system. The nonlinear features of the forward kinematics of the industrial robot arm drive are thoroughly modelled based on the forward adaptive neural NARX model-based identification process using experimental input-output training data. This paper proposes the novel use of a back propagation (BP) algorithm to generate the forward neural MIMO NARX (FNMN) model for the forward kinematics of the biped robot's 3-DOF arm system. The results show that the proposed adaptive neural NARX model trained by Back Propagation learning algorithm yields outstanding performance and perfect accuracy.

View full abstract

This paper presents modified SFOC control of Doubly Fed Induction Generator (DFIG) wind turbine during grid unbalance for improved stability by using hybrid PI-Fuzzy controllers and eliminating negative sequence components. The system consists of a common induction generator with slip ring and power electronic converters at both stator and rotor sides. The modifications are applied to rotor side converter for active and reactive power controls of wind turbine. The turbine, generator and control units are also described. The investigation is based on MATLAB/SIMULINK. Simulation results show improved stability of active and reactive powers delivered by DFIG.

View full abstract

This paper presents results obtained in development of a hybrid suspension system combining functions of a magnetic spring and a magnetic damper. In the parallel connection of the developed magnetic suspension system with a metal spring, it is possible to make a soft spring near the middle point supporting a large mass by combining the negative spring constant with the positive one. The dynamic vibration characteristics of the developed hybrid suspension system are demonstrated.

View full abstract

Samples made of SCM415 bulk with hole defects of different depth were annealed at 855°C for two hours. A ferromagnetic oxide scale was produced and the defects were measured by EMAT using magnetostrictives. Their resulting images of defects were very noisy and blurred. First, we performed noise-reduction on a sample with internal defects 10mm, 20mm, 30mm and 40mm deep. The echo signals were identified clearly. Second, we developed a theory of ultrasonic wave propagation and measured the response function. A sample with hole defects of different diameters was prepared and image reconstruction was applied.

View full abstract

In the electrostatic analysis, we usually treat the effect of polarization charges on dielectric surface and true charges on conductor surface. When we solve problems with high permittivity using the surface charge method, we cannot get accurate solutions due to cancellation errors. In this paper we propose a novel approach to solve the problems with high permittivity. The boundary integral equation in the proposed method is derived by replacing the polarization charges by loop currents instead of surface charges used in the surface charge method. The proposed method is effectively applicable because it contains only one unknown. Besides, even though the loop current gives originally scalar potentials, Biot-Savart law gives directly the electric flux density. Finally, we have compared the proposed method and surface charge method by solving some typical examples.

View full abstract

The cause of angle difference between B vector and H vector (θ_BH) is made clear by means of numerical calculation taking into account of the magnetic hysteresis and magnetic anisotropy. Since the θ_BH, which is measured by the 2D magnetic vector property method, is usually ignored in the numerical calculation of electromagnetic field, it is our necessary to consider its effect on the numerical calculation. The research work says the θ_BH is possible to be expressed by the magnetic hysteresis phenomenon and the magnetic anisotropic phenomenon in numerical calculation of magnetic field. Therefore, the development to create the θ_BH model is not always necessary.

View full abstract

EDLCs offer high energy density and long life span, so various applications may be anticipated in the realm of energy storage devices, such as those used in electric vehicles or electric power stabilization in power systems, etc. However, since the voltage limit is low of the devices, it is necessary to connect them in series or parallel. In addition, it is required that they be used in the region of their critical voltage limit or capacity limit. In order to apply them efficiently, the devices should be used with balanced voltage. In this paper, a novel voltage equalizer and modified versions are presented, employing a CW (Cockcroft-Walton) circuit. Characteristics of proposed circuit are analyzed and improved especially about charging response charging capability.

View full abstract

When a spherical motor with multi degrees of freedom like a human shoulder joint is in practical use, a lot of systems with multi degrees of freedom will be compact, lightweight, and high performance. However, the motors are controlled by open-loop, as there are no good rotor posture sensors. This paper reports the basic experimental results of a developed posture sensor with two mouse sensing devices. The basis transformation matrix is used to represent the rotor posture. At first, researches of the posture sensors for the spherical motor are reviewed. Among the previous work, select a posture sensor with two mouse sensing devices. Show the advantages of using the basis transformation matrix to represent the rotor posture. The basic ideas for getting the posture from the data of two mouse sensing devices are presented. A posture sensor with two mouse sensors is developed and tested.

View full abstract

We have proposed a non-contact electromagnetic impact-torque mechanism (EMI mechanism) using induced current, and its characteristics have been verified by using 3-D finite element method (FEM) analysis and carrying out measurements on a prototype. This paper describes an optimization method of the parameters of the electromagnetic impact system - such as dimension and number of poles - using the Design of Experiments (DOE) method. From this result, we can obtain a design guide for constructing an efficient EMI mechanism by using the DOE method.

View full abstract

This paper presents local vector magnetic property distributions in a three-phase tripod transformer model core. The measurements were performed by using a localized vector magnetic property measurement system consisting of a three-axis positioning system and a vector magnetic sensor (V-H sensor). As a result, we made clear the local distributions of the magnetic flux density trajectory, field strength trajectory, hysteresis loop, and iron loss. The results show that the local magnetic properties have large influence from the segmented core construction, the jointing parts and the crystal grain distribution.

View full abstract

This paper presents the design and analysis of two-degree-of-freedom actuator that can move in rotary and linear direction. The proposed actuator is moved in principles of permanent magnet synchronous motor and linear synchronous motor. The structure of the actuator is robust to use the ring magnets that magnetized in axial direction. Moreover, the stator of the actuator has the salient pole in axial direction for improvement of thrust density. Characteristics of the actuator are analyzed by three-dimensional finite element method. As a result, the actuator is obtained characteristics that the average torque is 61.8 mNm in rotary motion and the average thrust is 9.00 N in linear motion.

View full abstract

This paper presents effect of stress on vector magnetic properties and two-dimensional magnetostriction of a non-oriented electrical steel sheet. In order to evaluate two-dimensional magnetostriction under stress in the electrical steel sheet, a new six-axial stain gauge is developed. Results reveal that the amplitude and direction of the magnetic field strength vector and magnetostriction differ strongly due to the tensile and compressive stresses. In particular, it was clear that the direction of the magnetic field strength vector and magnetostriction was not parallel to the applied stress direction. In addition, the peak-to-peak value of the magnetostriction and magnetic power loss increased when the stress is applied. Therefore, evaluation of the amplitude and direction in a two-dimensional magnetostriction is necessary in order to know the relationships between the magnetic properties and stress.

View full abstract

We have already proposed the fatigue evaluation method for the metallic material by measuring an inductance of a pancake-type coil using a LCR meter. This method was called the inductance method. This time, we have improved the conventional inductance method by using a low excitation frequency under a dc magnetic field generated by a neodymium (Nd) permanent magnet. The improved method was applied to the evaluation of a fatigue damage accumulation caused by partially pulsating stress in an iron-based structural metallic material (SS400). The new method was able to detect the change of the material condition such as a fatigue damage accumulation in SS400 without receiving the influence of the surface condition of the specimen. In this paper, we report the results of a fatigue damage accumulation evaluation using the new inductance method.

View full abstract

Many researchers and engineers to date have been researching applications for permanent magnets. Examples of a device in line with that research are a vibration sensor and a limit switch. These devices use a repulsion magnetic field with permanent magnets and this magnetic force is an important parameter in permanent magnets. When the poles between the two magnets are the same, this force is repulsive and when they are opposite, this force is attractive. If was confirmed in recent years that when two magnets are placed close together and arranged facing each other with a magnetic material on one of their sides, the repulsion force changes to an attractive force at the boundary point. The purpose of this paper is to measure the resultant force when the two magnets are placed close to one another under the above mentioned conditions. We also compared measured values to calculated values, and considered the validity of FEM analysis about calculation of magnetic force.

View full abstract

The extended Jiles-Atherton s model considered stress dependence is applied to silicon steel sheets and compared with the published hysteresis curves of silicon steel. Magnetic properties of silicon steel, which are important for the precise motor simulation, are affected by compressive stress. The extended Jiles-Atherton s model is found to well describe the published magnetization curves of silicon steel for small compressive stress, though it is difficult to express the magnetization property with large compressive stress. Since the silicon steel sheet has coating material on the surface and has different deformation ratio from the coating material, the different stress distribution generates within the silicon steel. It is considered to be a cause to make the different magnetic characteristics between the bulk steel and tie silicon steel sheets.

View full abstract

This paper presents the modeling and two-degree-of-freedom motion control of a piezoelectric bimorph actuator with hysteresis compensation. It has been demonstrated that with correctly applied voltage, the hysteresis effect can be substantially reduced. However, there still remains the problem of control. Two-degree-of-freedom control is a robust control technique that is effective for this actuator. It consists of a feed-forward controller based on an inverse system and a stabilizing feedback controller. Both experimental and numerical results are presented and show the effectiveness of both the control technique and the modeling method.

View full abstract

Microcharacterization of creep damage in structural materials of austenitic stainless steel has been performed using a magnetic force microscope in order to understand the degradation mechanism of structural materials in power plants such as advanced fast breeder reactors. Magnetic phases of δ-ferrite are observed in the weld metal of the as-received specimen, and these magnetic phases are interconnected. Magnetic phases of δ-ferrite are also observed in the weld metal of a creep-damaged specimen. However, in this case, the amount of magnetic phases decreases and they are not interconnected. Image processing analyses of the magnetic force microscope images indicate that the degradation of creep damage is related to the area fraction of magnetic phases and the standard deviation of magnetic force microscope images. The degree of degradation can thus be evaluated by microcharacterization using a magnetic force microscope.

View full abstract