We propose a current superimposition variable flux reluctance motor, which consists of 6 phases. This motor is driven using a 3-phase vector control because the 6 phases consists of 2 sets of 3 phases. However, the phase current contains harmonics because the 3-phase vector control is applied to composition currents. In this paper, a control method to reduce the copper losses is proposed. The torque generation mechanism focusing attraction forces are described. Finally, the influence of the current harmonics on the torque and copper loss is investigated.
This paper presents influence of induction heating treatment with a cylindrical magnetic flux concentration plate on vector magnetic properties of a non-oriented electrical steel sheet. The non-oriented electrical steel sheet is heated by using induction heating method. The vector magnetic properties of the non-oriented electrical steel sheet under alternating magnetic flux and rotating magnetic flux conditions are measured with a easily vector magnetic property measurement system. From these results, it was clarified that amplitude and the inclination angle of the loci of the magnetic field strength vector differ by changing the heating time and voltage. In addition, it is possible to decrease the maximum magnetic field strength, coercive force and the magnetic power loss of the non-oriented electrical steel sheet by using the induction heating.
The electromagnetic levitation technology which an object grips and transport without contact is focused, and actively considered in various approach. Considering stability of levitated object, the levitation method which inclueds mechanical properties of levitated structure is also considered. Application of the levitation technology in manufacture process for thin steel plate is demanded for enhancement surface quolity of products. However, the elastic vibration of steel plate is excited because of flexibility, and prevent stable levitation. To solve this problem, we have proposed a levitation method for 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, we applied sliding mode control theory to the bending levitation system using continuous model, and carried out levitation experiments. These results show that applying sliding mode control theory further improve levitation performance.
Since the ultra-compact electric vehicle does not generate an engine sound, an interior noise caused by road and wind noise have a large impact on user comfort in the interior space. In this study, we propose a system whereby giant magnetostrictive actuator is installed on the front window of an ultra-compact electric vehicle to actively cut interface vibration noise, i.e., road noise, transmitted to the interior of the vehicle and we aim to reduce the noise level in an interior of a vehicle using this proposed active noise control system. Also, we studied fundamental consideration of masking. In this study, we evaluate the vehicle interior comfort by using living body information measured the brain waves of the crew.
In this paper, we analyzed the interbar current in the steel sheets of squirrel-cage induction motors using the 3-D parallel finite element method and clarify the influences by the difference in the shape of skew and the number of rotor slot on the interbar current.
Movement of a capsule endoscope in body depends only on the peristalsis and gravity. Therefore, there is a problem such as prolongation of the examination time. In addition, observation of the site aimed at is not easy. It is required to control the movement of the capsule endoscope to reduce the oversight of a lesion. Towards the resolution of the problems, this research proposes a magnetic guide method using a magnetic guide magnet. It is guided the capsule endoscope by the magnetic force generated from the magnetic guide magnet. Assuming the distance between the surface of the body and digestive organ, the goal of guide distance is 100 mm. Estimates of necessary magnetic field for the guide of the capsule is 17 mT. This paper reports the design of the magnetic guide magnet which generate more than magnetic field of 17 mT to a distance of 100 mm.
High-speed and long-distance elevator systems have a serious issue that a large impact force from an emergency stop device injures the passengers in an elevator cage during the emergency stoppage. Therefore, we focused on the safety of the passengers in an elevator cage and proposed a new emergency stop device that consists of a spring and a magnetorheological fluid damper having the variable damping coefficient by a controlled magnetic field. In this paper, we would like to introduce our test installation that consists of the spring, the magnetorheological fluid damper, sensors, a digital controller with LabVIEW and a linear actuator for simulating the deceleration of the emergency stop device. Additionally, we evaluate the fundamental performances of our proposed device that was measured by using the magnetorheological fluid damper as a passive mode.
It is well known that the skin effect occurs at high frequency excitation, and the lamination of the steel sheets will affect on the distribution of the eddy current. In this paper, laminated core and wound core type toroidal reactor is calculated using the 3-D finite element method. The effect of the lamination of the steel sheets at high frequency excitation is clarified quantitatively.
Realization of a magnetic levitation and conveyance system for very thin steel plates has been desired to keep the plate surfaces to be intact. However, it is very difficult to levitate thin steel plates stably, due to its magnetic saturations and its flectional characteristics. Nevertheless, we have already performed stable levitation of 1.6mm thick steel plates. In this paper, we will achieve stable magnetic levitation of a 0.18mm thick steel plate, and confirm its stability against various disturbances considered in an actual process and conveyance line.
We have proposed a current superimposition variable flux machine for traction motors. The torque-speed characteristics of this machine can be controlled by increasing or decreasing the DC current which is superimposed on the AC current. However, because of noises and the change of coil resistances, the DC current was difficult to apply constantly. In this paper, we propose a DC current control method and verify the effectiveness by carrying out measurements on a prototype. First, the structure and control method are described. Next, the effectiveness of the proposed method is verified by using FEA. Finally, the N-T characteristics are measured on a prototype.
Multi-degree-of-freedom (multi-DOF) actuators have been developed for the fields of robotics and industrial machinery. We have proposed an evaluation method for the multi-DOF actuators based on a torque equation and singular value decomposition under constant power. However, the evaluation method does not take into account a current density. In this paper, we propose a new evaluation method considering an allowable current. Finally, the static torque characteristics of a previously developed multi-DOF actuator is evaluated using the proposed evaluation method.
Recently, a high-quality image has been obtained by a digital camera because imaging performance was improved. On the other hand, image quality deteriorations due to the vibration has become a problem. In this paper, we propose a three-degree-of-freedom actuator for image stabilizations. The basic structure and operating principle of the actuator are described. Moreover, the dynamic performances under position feedback control are analyzed employing 3-D finite element method and the effectiveness of the actuator is verified.
Previously, we have succeeded in exploiting a new high sensibility eddy current testing (ECT) sensor called the infinite (∞) coil. In addition, this paper proposes the other new ECT sensor to realize a further high sensibility sensor than those of our previous one. The new sensor utilizes the magnetic fields in the parallel directions to a tested target surface, and this makes it possible to construct a shape whose sensing coil could be entirely surrounded by the exciting coil. Surrounding the sensing coil entirely by the exciting coil makes it possible to work the exciting coil as if a shielding coil to the external electromagnetic noise. Thus, good signal to noise ratio is expected and has been confirmed by the numerical simulations as well as practical experiments.
Atmospheric-pressure plasmas can disinfecting and disintegrating hazardous materials and modifying material surfaces. Although the mechanism of action remains unclear, new biomedical applications of plasma have been found. We believe that the mechanism of plasma should be clarified. Plasma technologies have diverse applications, such as skin regeneration by multiple low-energy plasma therapy. On the other hand, hypoxic-ischemic encephalopathy (HIE) is a condition in which the brain does not receive enough oxygen. When brain cells fall into the acid deficient state, it begins to death in just less than 5 minutes. Cause of HIE is various, for example, respiratory failure and circulatory failure, neonatal asphyxia. We want to conduct an experiment on the functional recovery of the HIE by atmospheric pressure plasma inhalation. We guessed the effect of the plasma to the HIE model rats, was studied evaluation method.
Nowadays, ultra-compact electric vehicles are sold by several automobile's companies. Transport and Tourism, increasing the attention directed toward ultra-compact electric vehicles because of environmental issues and the aging of the society. The ultra-compact electric vehicles currently being sold are not equipped with the system for assisting the driver's steering, such as power steering. The steer-by-wire systems of interest in this study have the advantage that the steering operation of the driver can be controlled by setting the change in the reaction force actuator mounted on the steering device. There are some previous studies on the operation of the steering wheel, but the physical burden and feel of the driver in continued steering operation maintaining a constant steering angle have not been sufficiently studied. In this study, we examined by subjective evaluation and surface EMG, the muscle burden of the upper arm, which is predominantly used in the driving operation.
Heat treatment of non-oriented electrical steel sheets is performed in a magnetic field in order to control microstructure orientation and magnetic characterization. Magnetic field (0.5T-5T) is applied to specimens in a direction parallel to the rolling direction during heat temperature from 1023K to 1123K. Specimens magnetically heat treated, showed anisotropic characterization due to crystallographic orientation under high magnetic exciting condition. Recrystallization texture and orientation of specimens are characterized with X ray pole figure analysis. Magnetic heat treatment is found to enhance the selection of (100) or (110) plate parallel to electrical steel sheet surface.
The production methods and the electric characteristics of coils made by the use of sewing technology were described. These coils were assumed to be used in magnetic coupling of wireless power transmission for small electronic devices. The sewed coil was produced using two methods of a cross-stitch and a conventional sewing machine. The inductance of one of the sewed coil was measured and compared with the Qi coils. The coupling coefficients between a Qi receiver coils were measured. The maximum coupling coefficient was 0.78. The power efficiencies were measured to be 76% for 10-ohm load resistance. We showed that the sewed coil could be used as the transmitting coil for small electronic devices.
An AMB is not widely used because of its high cost and because its dimensions are significantly larger than those of mechanical bearings. Since a 6 salient-pole type AMB has fewer poles than the usual 8 salient-pole type AMB, it is easier and less costly to miniaturize. However, because the magnetic circuit is not independent in the x and y directions, bearing forces for coil currents become complicated. To solve this problem, two control methods have been proposed. One is a minimum energy control method, which minimizes copper loss in coils. The other is a maximum bearing force control method, which generates a larger bearing force than that of the minimum energy control method. In this study, the two control methods are introduced and rotational tests are carried out for comparison. The rotor could rotate up to 53,000 rpm with the minimum energy control and maximum bearing force control methods. Moreover, rotational tests were carried out with attaching a weight to the rotor. The rotor could rotate up to 42,000 rpm and 38,000 rpm with the minimum energy control method and maximum bearing force control method, respectively. Experimental results show that the minimum energy control method provides less power consumption than the maximum bearing force control method. On the other hand, the maximum force control method provides smaller maximum coil current than that of the minimum energy control method.
Electromagnetic type linear oscillatory actuators are used in many devices because of high controllability and small size. We developed a linear oscillatory actuator with two movers that can independently drive by impressing single-phase or two-phase voltage. The proposed actuator has two difference vibration characteristics, and it effectively generates vibrations with differential frequencies. In this paper, the dynamic characteristics are clarified by finite element analysis.
We have developed a magnetically levitated total artificial heart. The stator of the device has a magnetic bearing and a motor stator set at center of the device. The left and right impellers are connected by a shaft through the center hall of the stator core. The axial position and tilting of the levitated impeller are controlled by the magnetic bearing. The radial displacement of the impeller is supported with a passive stability. We propose the application of a repulsive passive permanent magnetic bearing, PMB, for improvement of the radial stiffness of the device. A magnetic field analysis with finite element method was performed to investigate a suitable PMB. As a result, the PMB which has two radially magnetized outer permanent magnets and an axial magnetized inner permanent magnet has better performance and the radial stiffness increased up to 2.5 times of passive stability's one.
Amplitude of linear resonant actuators severely decrease when external loads are applied. Therefore, load feedback is essential. Authors have proposed a load estimation method using two back-EMF signals under free damped oscillation. This paper presents a new estimation method based on the law of energy conservation under forced oscillation. Additionally, a disturbance compensation control is proposed using estimated load. These methods are verified through finite element analysis.
A 5-degrees of freedom (5-DOF) controlled maglev motor and a centrifugal blood pump have been developed for pediatric ventricular assist devices (VADs). The magnetically suspended pediatric VAD consists of a top stator, a bottom stator and a levitated impeller. A double stator mechanism enhances a torque production. The maglev pediatric VAD has an outer diameter of 22 mm, a total length of 34 mm and a total volume of 18 cc. In this study the pump performance of the developed centrifugal pump was investigated, as well as the magnetic suspension ability of the developed 5-DOF controlled self-bearing motor was evaluated. The developed maglev pediatric VAD produced a flow rate up to 2.5 L/min against a pump head pressure of 100 mmHg at an impeller rotating speed of 5000 rpm. The maximum oscillation amplitudes that were 0.08 mm in axial direction and 0.19 mm in radial direction were less than the clearance of the centrifugal blood pump.
Magnetic levitation technology is applied for durability enhancement of ventricular assist device. We have developed a pediatric magnetic levitated ventricular assist device using a radial type self-bearing motor. The radial type self-bearing motor consist of a stator and a rotor which has 4 permanent magnet on the inner surface of the rotor. The minus two-pole algorithm is adopted to levitate and rotate the rotor. Radial position of the rotor is controlled actively, and axial position of it is passively stable within the thin rotor structure. In this paper, two-dimensional magnetic field analysis of the self-bearing motor using 5 slots stator, 6 slots stator and 7 slots stator were performed, and an optimal slot number of stator for development of small diameter radial type self-bearing motor was examined. As a result, 5 slots stator is good slot number for the radial type self-bearing motor which has 4-pole rotor.
Eddy-current rail displacement sensors are used for confirming rail displacement. However, collision with gravel and snow due to the short distance between rail head surface and sensor causes failures or malfunctions. Therefore, it is necessary to increase the distance from the rail head surface to the eddy-current rail displacement sensor. So with high quality factor coil in order to realize a conventional double lift off. Electric field generated from the coil by the magnetic field is amplified to amplify. Susceptible to disturbances such as a high dielectric constant of water by the electric field is generated. Therefore, it is necessary to suppress the electric field is increased. It suppressed electric field by using an electric-field shielding. In this paper, it allowed the detection of rail displacement while suppressing the electric field by implementing an electric field shield.
Recently, propulsion structure using traveling wave is being researched. These structures are limited the range to apply. In this study, we develop the traveling wave generator. It can be adapted to various condition. It is composed three same actuators. These actuators are set the parallel to the output shaft. This actuator is composed four springs and two opposite permanent magnets. One side of the permanent magnet is rotated by a motor. And, other side of the permanent magnet moves linear with magnetic attraction power and repulsion power. The actuator is able to change the thrust and stroke by changing the spring constant. We evaluate thrust, range of movement, and so on. The result, maximum thrust is 67[N], maximum stroke is 15.6[mm]. And this actuator is able to drive 3～23[Hz].
This paper presents a novel magnetic lead screw actuator without helical permanent magnets. Magnetic lead screw actuator is high efficiency due to its non-contact transmission. It is expected to be applicable to interactive robots with human because of its compliance to external forces. The proposed actuator has simple structure comparing to the conventional magnetic screws. The result of the force calculation and structure optimization employing 3-D finite element method is reported.
The Maglev hydraulic power generator was developed. However, the power generation test results showed the power consumption of the eddy current sensor and the PWM amplifier were too high to maintain magnetically levitation control by using generated power. Therefore, this paper focused on the development of the low power consumption eddy current displacement sensor. The sensor circuit consists of the oscillation circuit, the resonance circuit, and the detector circuit. The circuit simulator “LT spice” was used to determine the parameter of each electrical component. And the sensor circuit was actually fabricated. The static characteristics of the fabricated sensor were tested. The results showed good linearity and low power consumption.
As magnetic material has magnetic hysteresis characteristics, there is a problem that gives an error in current sensor output. So it is important to clarify the influence of magnetic hysteresis phenomena in current sensor. The object of this paper is to propose a method in consideration of a magnetic hysteresis in a FEM software JMAG, and to analyze the current sensor using the proposed method. Magnetic loops are approximated by a sigmoid function. We propose a method for coupling magnetic hysteresis and an external circuit to change the detecting current in response to gap magnetic flux density. And it clarifies the error in current sensor due to magnetic hysteresis.
We focus on the hardness measurement by using a sensor unit arranging 8 piezoelectric elements in series. In previous study, it confirmed that the sensor unit is available to evaluate roughness on the sample. In the study, four silicone samples with different Young's modulus were prepared. In experiments, the sensor unit was placed on the sample and moved up and down with 1Hz. And the oscillatory waveform form each piezoelectric element was obtained. In analysis, the first peak voltage in the waveform were extracted and compared with the Young's modulus of the sample. From the results, it was found that the peak voltage related on Young's modulus. It was suggested that the sensor unit is available to evaluate the hardness of objects.
We developed the first prototype module robot units for a future implantable actuation device. It consists of a smart servo motor, wireless power supplies, wireless data communication devices, magnet-coupling actuation system, a waterproof case, and realized compact design: 78mm*64mm*52mm, 200g. We conducted performance-investigation and proved the waterproof property, maximum torque output 0.13Nm, battery use 220mins.
This paper presents measured results of the two-dimensional vector magnetic properties in non-electrical steel sheets for different thickness under high frequency excitation conditions. Mars Orbiter require small size high power motor. In order to obtain its, it is necessary to rotate a motor under high-speed. However, motor efficiency reduces under high-speed rotating because magnetic properties such as field strength in motor core are changed depending on the exciting frequency. In this paper, the relationship between the magnetic flux density and field strength vector and iron loss is measured by using a vector magnetic property measurement system. Moreover, the iron losses of stator core are compared with its made of different sheet thickness under high-speed rotating.
Using the diamagnetic magnetic force of bismuth, the author succeeded in magnetic levitation in a non-controlled and non-rotating stationary state. Furthermore, by applying a rotating mechanism, it became possible to work as a non-controlled magnetic levitation motor. The author examined the placement of the permanent magnet that can float by experiment and numerical calculation and found the optimum combination of permanent magnet and diamagnetic material.
This study proposes long-range nondestructive inspection of the inner surface of a pipe without open end using microwave emitted by a probe attached to the pipe wall. Three-dimensional finite element simulations were conducted to evaluate how to propagate microwave effectively inside a pipe having an inner diameter of 19 mm. The simulations considered a coaxial cable penetrating the pipe wall to emit microwave inside the pipe. Experimental verifications were then carried out using a brass pipe with a total length of 4.5 m and a probe fabricated on the basis of the results of the numerical simulations. The experiment confirmed clear reflections due to artificial wall thinning 1 m away from the probe situated approximately at the center of the pipe. The experiment also revealed that directivity of the microwave depended on the frequency, which agrees with the results of the numerical simulations.
A lens-unit-swing system is composed of lens and an imaging device for image stabilizations. This system can correct an image from camera shakes over wide rotation ranges around three axes. On the other hand, this system has some problems such as an increase in size and power consumption. Therefore, three-degree-of-freedom actuators are expected to become a solution for these problems. However, it is difficult to incorporate these actuators in the system because the size is large and it has a complicated control system. In order to solve these problems, we propose a new three-degree-of-freedom electromagnetic actuator, which can be controlled by a simple control system. In this paper, the basic structure and operating principle of the actuator are described. Moreover, the modeling method of the actuator is described. In addition, the effectiveness of the actuator is verified through 3-D finite element analysis and numerical simulation.
In recent years, high rotational speed of IPM motors is required for applications like Electric Vehicle(EV). In case of rotors having same shape, maximum against centrifugal force is decided by the strength of rotor core. Therefore, it is possible to achieve higher rotational speed if higher strength steel plate, instead conventional silicon steel plate, is used. However, in case of higher strength steel plate, the efficiency of motor drops as iron loss increases due to the degradation of its electromagnetic characteristics.●br●This paper reports on the efficiency of a prototype IPM motor with rotor core that using high strength steel plates having a yield point over 3 times higher than the conventional silicon steel plates. The efficiency of the prototype IPM motor is also compared with a rotor core that uses conventional silicon steel plates. It is found that although there is small drop of motor efficiency, the prototype IPM motor achieved a maximum rotational speed which about 2times higher than that of the conventional core IPM motor.