Recently, one of the most important problems is energy shortage. Therefore, it is required the high efficiency electromagnetic device like motors. One of them is interior permanent magnetic synchronous motor (IPMSM). It has a high degree of freedom of shape design because permanent magnets are placed in the interior of a rotor. This paper presents optimal design method of a rotor in IPMSM by differential evolution (DE). In the proposed method, magnets have design variables which are its width, length and coordinate. Flux barriers are expressed polygons which are composed by some nodes. These representations are used in simultaneous optimization of them with DE. Authors investigate usefulness of the proposed method by comparison of simulation results.
Currently, renewable energy has been attracting attention as a commitment to environmental and energy issues. However, renewable energy can't provide a stable power supply due to the influence of the climate. Therefore, we are aiming to development a “Power Charge and Discharge Device” to compensate for the fluctuation power using the magnetic levitation technology of superconductors. In this paper, the principles and characteristics of the proposed power charge and discharge device are described.
Natural frequency of magnetic elastomer beam is changed by applying a magnetic field. Relations of change of the natural frequency of magnetic elastomer beam and applying a magnetic field were investigated experimentally to develop a device using the phenomenon. The magnetic elastomer consists of a silicone gum and micrometer size iron powder. Furthermore, a longitudinal modulus of elasticity and logarithmic damping ratio of the magnetic elastomer were measured. And influence on the natural frequency was considered. As a result, it was revealed that the longitudinal modulus of elasticity and the logarithmic damping ratio of the magnetic elastomer hardly affected the natural frequency change.
These years, as we require the comfort at the time of boarding, it is proposed Active control engine mounts which is the equipment for automobile vibration suppression. For the ACM system, Filtered-x LMS adaptive control method which has a simple structure, is used. In this method, the transfer model that changes controller's output voltage into ACM's thrust, is needed. So, the model error is generated and system's instability is caused. In this paper, I would like to propose a method of determining the net parameters for the new LMS adaptive control algorithm which does not have to get the transfer model in advance.
Implanted batteries and transcutaneous drive lines are used for powering active implantable medical devices (AIMDs) such as pacemakers and nerve stimulators. However, those devices cause physical burdens to patients due to surgery of the battery replacement and infections through the drive lines. Hence, we have proposed an implantable energy harvesting system (IEHS) using the contraction energy of electrically stimulated muscles. Previously, we fabricated an electromagnetic induction generator for the IEHS. However, the generator is large and complex because of the requirement of speed increaser. Therefore, in order to realize a smaller and simpler generator for the IEHS, we focused on electrostatic induction generators without any speed increaser using electret which may generate electricity at lower rotational speeds. Firstly, we evaluated electric charge on the electret sheets measuring the surface potential. Secondary, we measured output power of the electrostatic induction generator having several combinations of gaps and the number of poles of the electret sheets. Finally, the output power was compared with that of the electromagnetic induction generator.
In the conveyance system of a thin steel plate production line, there is a problem that the quality of the plate surface deteriorates over time because the plate is always in contact with rollers. To solve this problem, electromagnetic levitation technologies have been studied. We propose a levitation of an ultrathin steel plate that is bent to the extent that the plate does not induce plastic deformation. It has been confirmed that vibrations are suppressed and levitation performance is improved. In this study, in order to examine the levitation stability and to compare the levitation performance, bending levitation experiments were carried out on the basis of the optimal control and sliding mode control theory which has robustness using thin steel plate with a thickness of 0.18 mm, 0.24 mm, 0.27 mm and 0.30 mm. It was concluded that using sliding mode control, levitation performance was constant regardless of tilt angle of electromagnets and higher than optimal control. Moreover, sliding mode control showed desirable levitation performance against disturbance. Therefore, we confirmed the utility of sliding mode control to a bending electromagnetic levitation system.
In recent years, ultra-compact electric vehicles have been marketed by a number of automobile manufacturers. These vehicles are reportedly desirable as they provide independence for elderly people who tend to not go out often and may feel isolated. Therefore, with an aging population, the demand for ultra-compact electric vehicles is expected to increase in the coming years. Despite these advantages, there are many problems to be solved in terms of the safety and comfort of ultra-compact electric vehicles as mobility means for elderly people. Ultra-compact electric vehicles for elderly people require that the vibration be reduced additionally in light of their cognitive function. On the basis of these considerations, the authors suggest an onboard active seat suspension (ASS), which uses a linear motor for a more comfortable ride. This study clarifies the improvement of visual field stability by the ASS on the basis of an evaluation by electrooculogram (EOG), and it shows the possibility of practical vibration control.
In the transport system of a thin steel plate production line, the quality of the plate surface deteriorates over time because of contact with rollers. Accordingly, studies of electromagnetic levitation technology have been carried out. However, when a flexible thin steel plate is targeted for levitation, levitation control becomes difficult because the thin plate undergoes increased deflection. To solve this problem, we propose a hybrid system to control levitation of thin steel plates using the attractive force generated by permanent magnets. In this paper, we searched the optimal placement of the permanent magnet attractive force is considering the phenomenon of change in the distance between the permanent magnet is changed. Furthermore, we carried out magnetic levitation experiments to confirm levitation stability. As a result, optimal placement of considered attractive force could suppressed deflection of steel plate compared to optimal placement of not considered attractive force. In addition, we could confirm the same tendency in the levitation experiment.
Mechanical parts, plants and cross-linkages inspected with MT are typically complex 3D shapes. In the complex 3D shape portion, because a magnetizer often cannot be configured to the inspection portion and the test object cannot be appropriately magnetized, there is a possibility of overlooking a crack in such an instance. Thus, MT system development that was successfully able to detect omnidirectional cracks in 3D shape portions was considered in this study's trials. Two magnetizers were hence arranged face-to-face, and the magnetization of omnidirectional scenarios for all surfaces of 3D shape test object (arranged in between both magnetizers) was evaluated.
A current superimposition variable flux machine using permanent magnets that can control its torque constant has been proposed. This machine aims to improve the efficiency of the current superimposition variable flux reluctance machine by using permanent magnets. In this paper, the computed characteristics by carrying out measurements on a prototype are verified. The structure and operational principle of this machine are described. First, the cogging torque and EMF are measured. Finally, the N-T characteristics are measured under vector control.
In recent years, industrial plants and social infrastructures have been aging. As the countermeasure, non-destructive testings are highly expected. Because ultrasonic guided waves can propagate over long distance with low attenuation, they are suitable for non-destructive testing for long structures such as rods and cables. One type of ultrasonic transducers is an electromagnetic acoustic transducer (EMAT), which is composed of magnets and coils. It is capable of generating a variety of ultrasonic waves by selecting configurations of magnets and coils. In this paper, for the purpose of generating higher-order modes of cylindrical guided waves, considering possible configurations of EMATs, we conducted experiments of guided waves transmitted and detected by EMATs for an aluminium rod. We calculated group velocities from measuring propagation time. Experimental results of group velocities, showing good agreement with theoretical ones, confirmed generation of higher-order modes. Further, numerical simulations also confirmed it by showing displacement distributions of corresponding modes.
It permeates widely in an industrial field, and a linear motor is applied variously. Linear DC motor (LDM) often fits the drive field of which you request single stroke fast response below the 100 mm in particular. Under the condition of limited power supply capacity and an outside dimension, the structure of LDM is investigated. We especially focus on number of turns, and investigate maximum delay time of displacement command to displacement response is within 150 μs. In case of coil with 68 turns, measured of maximum delay time is 108 μs, so the target is achieved. Number of turns is changed to fast-response, and coil with 40 turns is optimum condition. In case of E = 24 V, maximum delay time of 68 turns and 40 turns are 108 μs and 95 μs respectively, and maximum delay time of 40 turns reduced 12 % than that of 68 turns.
Magnetorheological elastomers (MREs) are composed of silicone and iron powder so that they can possess ferromagnetic and viscoelastic properties. The shape and the stiffness of the MREs change depending on the magnetic field. Therefore, it is expected to be used for an artificial muscle or damping material. However, it is difficult to design because ferromagnetic and viscoelastic properties greatly change depending on ratio of the iron powder and strength of magnetic field. This paper presents a numerical method for MREs analysis by coupling a particle method with a finite element method (FEM), in which the nonlinearity of MREs as Young's modulus, Poison's ratio and stiffness is taken into account. The numerical algorithm is described and calculated results are shown.
Onboard REBCO (rare-earth barium copper oxide) HTS (high temperature superconducting) magnets for SC (superconducting) Maglev vehicles are being developed, that do not require refrigerants such as liquid helium. Their simplified refrigeration system results in reduced vehicle weight and makes it possible to reduce the gap between the SC magnets and guideway coils. HTS magnets are designed to operate with constant current leading by an excitation power source. By using the power source, magnetomotive force of SCMs (superconducting magnets) can be controlled. This paper describes effects of magnetomotive force control of HTS magnets on the SC Maglev vehicle system in terms of rating and efficiency of the Maglev LSM (linear synchronous motor). Using onboard REBCO HTS magnets with magnetomotive force control, the efficiency of the SC Maglev vehicle system can be increased with the same rating of the system.
The compact magnetic circuit, which is composed of force coil, permanent magnet and yoke with larger output is strongly desired to realize downsizing of the weighing cell based on electromagnetic force restoration. New magnetic circuit we have developed is a higher output than the ordinary magnetic circuit. In this study, we have compared the actual measurement result with the analysis result to investigate the detailed magnetic properties of the proposed magnetic circuit. And, we have confirmed the validity of the design.
An implantable ventricular assist device requires that to have a high durability and efficiency, to flow blood without non-sliding, and miniaturizing the device. Therefore, we have developed a ventricular assist device using a radial type self-bearing motor. In the self-bearing motor, the radial position of the rotor is controlled actively, and the axial position of the rotor is passively stable within the thin rotor structure. In this paper, the estimating equation of the restoring force corresponding to the self-bearing motor's the passive stability in the axial direction was developed in order to reduce the designing time and elucidate the magnetic suspension characteristic. The estimating equation has the sufficient calculation accuracy that can be used for the prior design of the magnetic field analysis. The estimating equation has elucidated the interaction of the permanent magnet field and the magnetic field of rotation.
Flexible cushioned tactile sensors are important for safe interaction between humans and communication robots, and therefore, several types of sensors have been developed. However, these sensors have problems in durability and maintainability because they have wirings or solids in their fragile flexible part. In this study, we propose a magnetic type flexible tactile sensor that does not contain any wiring and any solid except for minute particles of iron in its surface flexible layer. The sensor has a permanent magnet and a magnetic sensor at the bottom of its flexible layer and detects deformations of the surface layer containing iron particles (magnetorheological elastomer) as changes of the output of the magnetic sensor. Simulation results and experimental results with a developed sensor showed that the proposed sensor can measure depths of surface depression produced by normal forces, and that the sensitivity and the measurement range of the prototype sensor depend on the thickness of the both elastomers.
A square wave excitation is the simplest method of brushless DC motor drive, but it has part inferior in terms of efficiency and vibration noise. However, the efficiency can be clearly improved by extending excitation angle and advancing current phase angle, especially the 150 degree excitation leads maximum efficiency. And the 150 degree excitation has possibility of making vibration noise characteristic improve because it leads losses decrease. In this paper, we measure the motor vibration noise characteristics in 150 degree excitation, and inspect degree of improvement of the characteristics experimentally.
A new novel blood pump with a maglev impeller has been developed to recover cardiac functions. The pump's rotational speed is modulated based on synchronizing with the heart beat in order to increase the coronary flow to recover the patient heart. Levitation stability of radial axes of the pump operated in constant speed mode and pulsatile mode was evaluated with a mock circuit filled with water when the pump is set horizontally and/or vertically. Levitated impeller is contacted with pump casing in the pulsatile mode when the pump is set vertically. Radial fluid force of levitated impeller is estimated by computational fluid dynamics analysis when levitation impeller is displaced 0.0 mm and 0.4 mm toward radial axis. Radial fluid force with an impeller displacement of 0.4 mm is 2.8 N and it is three times greater than that with a displacement of 0.0 mm. The size of permanent magnet in the magnet bearing should be enlarged to improve axial attractive force in order to prevent contact between levitation impeller and pump casing.
Elderly and physically handicapped persons are increasing in japan. They decreased physical ability, it is difficult to ADL. Support of their ADL is an important issue. Independent walking is important in ADL. The walker is support equipment to independent walking. But turnover is problem in walk with the walker. In this study, to develop of turnover prevention device of the walker. Definition of turnover judgment is not established at this stage. First, establish turnover judgment indicators. In this paper, we measure action and force and speed, were investigated turnover judgment indicators. And, focusing on force acting on the walker, examined the indicators by time variation of force.
Halbach array is effective in forming a strong magnetic field. However, the conventional model is difficult to control the magnetic field because all the rectangular shaped permanent magnets are strongly fixed. Proposal Halbach array is constructed with cylinder shaped permanent magnets and rotating all magnets to control the magnetic field. The magnetic flux distribution of the Halbach array using cylinder shaped permanent magnets has been measured actually and simulated to provide the details on the magnetic performance of the proposal model. In the Halbach array using cylinder shaped permanent magnets, by synchronized rotation in the same direction with of all magnets, the slide of the magnetic field distribution has been confirmed. In this paper, it reveals that the features of the proposal model by comparing the detailed measurement and simulation results.
In order to evaluate the energy transmission efficiency of capacitive coupling energy transmission systems for an implantable medical device, a precise measurement of received voltage on the order of megahertz is required. In this study, an investigation of a measurement method for received voltage is conducted, when electrical energy is transmitted from the surface of a human phantom (primary) to an implantable device inside this phantom (secondary). To prevent the common-mode current between primary and secondary sides through the ground line, the oscilloscope on the secondary side is driven by an uninterruptible power supply (UPS). In addition, a common-mode filter is inserted in the transmission line. Three types of voltage probes (passive, active, and differential) are used for measuring the received voltage in through the oscilloscope. As a result，an error rate below 0.0003% of the received voltage and a common-mode current of less than 0.9 mA can be obtained from the experiments, when a differential voltage probe is used.
Microwave plasma has been widely used for plasma processing. However, most of the antennas used for the process have been designed without considering the influence of plasma. For that reason, microwaves could not radiate effectively actually. So, we simulated it by using an electromagnetic analysis software and tried to understand the problem. Based on the results, in order to irradiate microwave toward the chamber efficiently, we changed the shape of the waveguide slot antennas from a rectangle to an ellipse for the microwave plasma processing apparatus. As a result, we were able to improve S-parameters (S11) from approximately 0 dB to -44 dB.
This paper presents design studies on a hybrid excitation motor (HEM) and experimental drive characteristics of the HEM for hybrid electric vehicle drive applications. Taking an IPMSM installed on PRIUS'2010 as the object of a comparison, the HEM is designed by means of trial and error using 3-dimensional finite element analysis (3D-FEA) and built as a test machine. With comparisons between the measured and the 3D-FEA-computed drive performances of the test motor, it is verified that the proposed HEM is a viable candidate as high efficiency motor for the target application.
A magnetic fluid is the functional fluid that move in response to magnetic field. The magnetic fluid can be applied to sensors, actuators, and electromagnetic devices because the magnetic fluid has fluidity and magnetism. However, a mechanism of magnetic fluid movement under a magnetic field remain unsolved. In this paper, the movement of magnetic fluid under a magnetic field is valued with meshless analysis method employing particle method and magnetic moment method well known as integral equation method.
This paper presents the development of high efficiency (IE5-class) industrial motor with an amorphous core for large capacity applications. Interest in saving energy increases on a global scale, and the high efficiency of the motor attracts attention. As for the motor of the field of industry, legal regulation to IEC standard is promoted in each country. We developed the magnetic characteristic evaluation technology and highly precise analysis design technique in the motor to reduce a loss more from the IE4 efficiency class. We found core structure to reduce the loss of the amorphous metal core, and the trial motor was able to achieve an efficiency class of IE5 by applying it.
A wind tunnel system for a spinning body was developed for the measurement of the hydrodynamic forces acting on the body. In that system a ferromagnetic sphere (body) was suspended and rotated by electromagnets. The forces acting on the body were measured from the control signal for suspension. However this existing arrangement is not still appropriate to observe accurate hydrodynamic phenomena around the floating object because the size of the wind tunnel is only 60×60mm. It is required to enlarge the size to reduce the interferences with the walls. In this work, a wind-tunnel system of 100×100mm is proposed to be fabricated. Before the development of the system, the electromagnetic analysis for the system has been carried out. A 3D model of the arrangement is taken in consideration for the analysis. The magnetic flux distributions as well as magnetic force acting on the suspended object are obtained. The magnetic flux densities are analyzed for the variation of current in electromagnets. Actual force acting on the body is also measured. It is observed that the experimental results support the results obtained by numerical analysis. Stable suspension and three-dimensional positioning of the body is achieved in the developed system. Spinning of the body is realized by superimposing two-phase AC signals on the control signal.