A number of automobiles have been fitted with electric motors and their inverters. In order to reduce the space of motors, we have proposed a motor with two controllable rotors, which consist of 2 rotors and 1 stator. However, the previous motor was difficult to be practically used due to its complicated structure. Therefore, we proposed a novel motor with 2 controllable rotors. In this paper, in order to investigate a magnetic interference between 2 rotors, the cogging torque and N-T curve of the 2 rotors are computed using 3-D finite element analysis.
We have developed a current superimposition variable flux reluctance motor that has 10 salient poles in the rotor and 12 slots in the stator. However, iron losses of this motor in the high rotation speed is high because the number of poles is large. In this paper, we propose a current superimposition variable flux reluctance motor that has 8 salient poles and 12 slots. The characteristics of the 10-pole-12-slot and 8-pole-12-slot current superimposition variable flux reluctance motors are compared using finite element analysis under control.
Traction motors of EVs require wide power band characteristics. A magnetic-geared motor has a possibility to achieve these requirements because it has passively variable magnetic flux characteristics. In this paper, the passively variable magnetic flux characteristics of the magnetic-geared motor is investigated using finite element analyses. Furthermore, a maximum torque control method for the magnetic-geared motor is proposed and investigated.
We have proposed a non-contact electromagnetic impact-torque device (EMI device) using induced currents, and its characteristics have been verified using 3-D finite element method (FEM) analysis and carrying out measurements on a prototype. Our previous EMI device could not generate sufficient torques under high rotation speed due to the impedance of the coil. In order to solve this problem, the electric circuit in the EMI device has been improved by using an electrical resonant phenomenon. This paper describes the influence of the electrical resonant phenomenon on the impact torque characterstics.
This paper describes the rotation angle sensorless drive of a helical teethed linear actuator (HTLA) for artificial muscle. The position control with vector controller is required the linear and rotary position of the mover of the HTLA. However, to simultaneously measurement the linear and rotary signals is required complicated structure. The proposed estimation method utilizes the magnetic saliency of the mover and linear encoder signal. In this study, the estimation accuracy of the rotation angle was calculated by 3D-FEM analysis and measured by prototype. In addition, we investigated the response characteristics under PID position control using the estimated rotation angle. As the result, the maximum estimation error is 7.5 deg. in the initial stable position of the prototype. Moreover, experimental result show that position control can be performed using the proposed estimation method.
Multi-degree-of-freedom (multi-DOF) spherical actuators have been developed for the fields of robotics and industrial machinery. In general, an actuating system with several-DOF is composed of single-DOF motors, which results in large, heavy and complicated structures. Therefore, multi-DOF spherical actuators are expected to solve these problems, and various actuators have been studied. Unlike single-DOF motors, the multi-DOF spherical actuators can generate torques in various directions at various positions. Due to this, it is difficult to measure the static torque characteristics. In this paper, in order to evaluate the static torque characteristics experimentally, a measuring torque constant method is proposed. This method can evaluate the static torque characteristics over the entire movable range by measuring several point. Finally, the effectiveness of this method is discussed.
The development of spherical actuators for robots and electric devices are expected in manipulations of machines that have multi degrees of freedom. We have developed a 2-degree-of-freedom outer rotor spherical actuator. In this paper, we propose a new control method to reduce current phases.
Ballscrew drive system has high mechanical efficiency and is able to get high gear ratio easily. But it also has non liner friction elements like rolling friction and viscous friction, so it makes ballscrew control accuracy worse. For that reason, it is proposed that inserting disturbance observer into control system and compensating disturbance torque. Generally, rotary encoder is used for position sensor in ballscrew control, but its resolution affects accuracy of drive control and disturbance observer. In this paper, we propose a speed control system using AC servo motor ball screw drive system, compare driving characteristics in low speed range when using low resolution encoder and high resolution encoder as position sensor. Also we examine effects for driving characteristics by using and compensating disturbance observer. These verifications were carried out by simulation and actual machine.
Wind power has a relatively low power generation cost than other power generation methods, attracting attention from such as it is high business profitability, and introduction has been expanding.
In this research, we aim to investigate the effect of secondary side excitation for DFIG and conduct research with the following contents. Study on power generation by secondary side drive method of DFIG. We clarify the principle of the secondary side drive method of the DFIG, simulate the wind turbine in the simulation, and examine the power generation characteristics and the efficiency according to the wind speed.
Although the mechanism of action remains unclear, new biomedical applications of plasma have been found. In addition, umbilical cord blood is clinically applied by hematopoietic stem cell transplantation. It was confirmed that mesenchymal stem cells capable of differentiating into brain and bone tissues exist in umbilical cord blood. It is expected that umbilical cord blood will be applied to the field of regenerative medicine from the existence of mesenchymal stem cells. On the other hand, hypoxic-ischemic encephalopathy (HIE) is a condition in which the brain does not receive enough oxygen. HIE is a fatal condition for brain falls into acid deficient state. 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 and umbilical cord blood to the HIE model rats, was studied administration method.
In recently, permanent magnet type linear motors (PM-LSM) which could control high speed have attracted attention in the industrial field. Our laboratory is focusing on conveyance system. In the loading and unloading of the luggage of the transport system, the mover to move repeatedly to "stop-and-go". This operation occurs each time to move the respective processing sections. This work leads to a reduction of transport efficiency. Therefore, we propose parallel synchronous drive. This method synchronizes the mover of the two LSMs. Because both movers in the synchronized state are the same inertia, luggage may be moved without the movers stop. Main line of the motor called “master motor” and another motor called “slave motor”. The master motor’s position is passed Slave motor and parallel synchronous drive is run. This paper reports a parallel synchronous drive method for transportation system of PM-LSM.
Conventional motors usually have bearings and gears, which have many problems such as metal powder occurred by abrasion and lubrication oil. Bearingless motor solve the problems because it has no mechanical contacts. It is often used in an application which need high speed rotating. However, it cannot generate high torque at low speed because of no gears. Recently, there are bearingless vernier motor which is new type bearingless motor applied technique of magnetic levitation on vernier motors. It can generate high torque at low speed. Reluctance type bearingless vernier motor has already been proposed in our laboratory. Consequent pole type bearingless vernier motor is proposed and whether it can generate torque and suspension force in the same way as conventional consequent pole type bearingless motor is investigated.
Recently, even though wireless communication technology has been developed, the power supply uses cables. The battery charged by a cable is used in an electric power supply. Wireless power transmission is currently being studied to improve cable failure. Generally, wireless power transfer is using circle shape coil. Recent years, considered using a corner shape coil, and the supply power of the circle shape coil and the triangle shape coil was elucidated in the preceding study. When the coil shape is corner in wireless power transfer, we thought so an electric current concentrates at a corner of a coil, and influence on sending and receiving. We reported research done on coil angle, position and distance, and the influence by which the shape of the send and receive coil shape gives it to the wireless power transfer was elucidated by inductive coupling type.
This paper discusses 40kHz IH inverter for indirect heating system and temperature control method of furnace using indirect heating system for aluminum alloy cast. Mostly, the heat treatment of aluminum alloy cast is technique of resistance heating. But the resistance heating furnace consumes more electrical power. For that reason, previous research provided indirect heating system using chain of mild steel. This method was done verification experiment using IH cooking heater. However, IH coking heater doesn’t have enough power for heat treatment. So, we attention to 40kHz IH inverter. In this paper, we describe heating performance of 40kHz IH inverter and temperature control method of indirect heating system using 40kHz IH inverter.
This paper describes the effect of power supply noise on the acoustic noise and pan vibration when making use of the IH (Induction Heating) cooker. Recently, due to the spread of power electronics device, noise superimposed on the AC power supply is a problem. It has been reported that the acoustic noise provides discomfort feeling when using the IH cooker. Other studies have concluded that the vibration of a pan due to the induction heating is the noise source. So, we started our study on the noise from a pan when making use the IH cooker. Furthermore, we clarify the influence of power source noise on the acoustic noise and pan’s vibration. We made an experiment to clarify this influence. As a result, we clarified that power source noise has influenced acoustic noise and pan’s vibration.
Mechanical circulatory support is one of the strongest candidate for heart disiese treatment. Research interest in pediatric circulatory support using ventricular assist devices (VADs) increases due to the succsessful use of VADs in adult heart failure therapy. In this study, a next generation continuous flow maglev VAD with a 5-degrees of freedom (5-DOF) controlled axial gap type self-bearing motor has been developed for pediatric circulatory support. The developed pediatric VAD prototype, which consists of a top stator, a bottom stator, a centrifugal blood pump and a levitated rotor impeller, has 31 mm in external diameter and 36 mm in hight. This paper investigated the disturbance force acting on the levitated impeller and the magnetic levitation stability in several driving condition of the centrifugal pump. The distrurbance force was estimated by using static suspension force and torque characteristics of the 5-DOF controlled self-bearing motor. The developed pediatric VAD suppressed the disturbance force and indicated non-contact levitation up to a rotating speed of 5000 rpm.
We have developed a small, thin, maglev ventricular assist device for mild heart disease patients. A radial type self-bearing motor are adopted to reduce the axial thickness of the device. The first prototype self-bearing motor had a narrow control range of 0.2 mm, and the maximum oscillation amplitude was also large. Improvement of self-bearing motor was carried out. The improved self-bearing motor has been expanded its outer diameter from Φ 30 mm to Φ 35 mm, and widened the air gap from 0.8 mm to 1.3 mm. In this paper, radial atractive force and levitation characteristics in the air of the levitated impeller of the improved selfbearing motor were assessed. The radial control range increased to 0.4 mm. The radial maximum oscillation amplitude decreased by 60%.
Electromagnetic type linear oscillatory actuators are used in many devices because of high controllability and small size. In previous studies, a linear oscillatory actuator with two movers and two coils that effectively generates vibrations in a wide frequency range by impressing same-phase or reverse-phase current, is developed. However, two H bridge circuits are needed for driving the actuator. In this paper, a new actuator with two movers that can drive using a three-phase inverter, are proposed. First, the characteristics of the proposed actuator are clarified by finite element analysis. Finally, there are compare with those of the conventional actuator.
The wireless power transfer is a technique to send electricity without having the mechanical point of contact. The wireless power transfer using magnetic resonant coupling has been studied. The charge to a cell-phone has already been possible by Wireless power transfer. Qi standards are used for wireless power transfer well. The output is less than 5 W. Frequency to use is 110-205 kHz. A wireless power transfer system having the output about 40 W will be necessary in future to charge an electric tool. In this paper, we performed wireless power transfer of output electricity 40 W using the magnetic resonant coupling. Transmission efficiency at 40 W transmission was measured. Also, we measured the radiation electromagnetic field at 40 W transmission. As a result, the efficiency between the coils achieved 91.7 %. The radiation electromagnetic field was less than guidelines on ICNIRP.
Eddy-current rail displacement sensors are used for confirming rail displacement. However the sensor causes trouble and malfunction by a collision with gravel and snow due to the short distance between rail head surface and sensor. Therefore it is necessary to increase the distance between rail head surface and sensor. It is able to detect rail displacement by using coil of high quality factor at twice the distance. Electric field is generated from the coil. The electric field changes by an object that have dielectric constant such as water and reduces precision of the rail displacement detection. Thus, it is necessary to reduce the electric field. In this paper, reducing an electric field by implementing the electric field shield to the sensor and, detecting rail displacement by using coil of high quality factor.
It is confirmed the commercial frequency magnetic field over 5 mT affects to some current sensors. The way to give current sensors immunity from the magnetic field required if when a problem revealed. The magnetic shield will be suitable for that use, such simple method to give current sensors immunity should be considerable. For evaluating shields, the spatially uniform magnetic field is needed, which is large enough to put magnetic shield in, also bigger magnetic flux density than 5 mT. The design method of the coil which fulfilled those requirements was considered, and we produced a box-shaped coil 25 cm on a side to generate uniform magnetic field over 5 mT. It can generate 6.09 mT with DC and 3.40 mT with commercial frequency, and it will enclose 60 % of the volume of the magnetic shield with uniform field which has 1 % deviation from center.
Linear DC motors often fit the drive field of which you request single stroke fast response below the 100 mm in particular. It is necessary to make the servo gain increased to drive LDM by fast-response. But displacement of LDM is easy to oscillate in increased gain. Amount of displacement is increase by pitching of LDM. It is desirable to install the displacement detection sensor at a position not affected by pitching behavior. This paper introduces the displacement detection position not affected by pitching.
Authors investigated whether the absolute sound pressure in the ultrasonic cleaning machine can be measured by fiber optic probe hydrophone (FOPH) under cavitation. Since the intensity on the cavitation bubble collapse is high in the frequency range of about 30 to 100 kHz, the sound pressure measurement using FOPH was applied to ultrasonic cleaning machine with the use of a submerged ultrasonic transducer with frequency of 35.5 kHz. In the case of cavitation bubble collapse occurs frequently, it is confirmed that fundamental and harmonic components can be measured by FOPH. And also, the sound pressure distribution was compared to the analysis result using finite element method.
This paper proposes a wireless energy transmission system for implanted devices for monitoring gastroesophageal reflux disease. One of the wireless energy transmission systems is transcutaneous energy transmission system (TETS). We developed a wireless power transmission system that uses a planar-type transmitting coil to send power to a planar-type receiving coil implanted deep inside the body. To obtain higher transmission efficiency, the transmission frequency and number of turns of the receiving and transmitting coils were modified. The relative performance of two methods of wireless power transmission, i.e., series compensated transmitting and receiving (SS method) and series compensated transmitting and parallel compensated receiving (SP method), was analyzed. The calculation result revealed that the maximum transmission efficiency of SP method was 0.8%, when the number of turns of receiving coil was 15 and that of transmitting coil was 22 at 0.9 MHz.
Recently, many medical electronic devices have been developed that can be implanted deep inside the body. The devices are designed to transmit information collected from deep inside the body for receiving antennas outside the body. Therefore, we proposed a wireless digital information transmission system that transmits datum from deep inside the body to the outside using capacitive coupling. Inverting amplifier and low-pass filter (LPF) circuit in the receiving circuit are necessary for shaping distorted waveform before transferring it to the peripheral interface controller. To determine the optimum transmit filter constant (e.g., cutoff frequency and amplification rate), communication accuracy is measured using a prototype digital information transmission and receiving circuit and simulated human body. The optimum setting value of the cutoff frequency and the amplification rate were determined to be 17 kHz and 20 times, respectively. However, the communication accuracy reduced by approximately 40% when electromagnetic noise voltage (1.8 V, 50–100 kHz) was added to the receiving wave. To overcome this problem, a common-mode choke coil was inserted in front end of the receiving circuit. Thereby, communication accuracy was improved to approximately 98.7%.
In this study, the transmission property of undersea magnetic field resonance type wireless power transfer (WPT) is reported. It is necessary to use a waterproof sealed case because transmission efficiency of the electricity decreases when a coil is wetted with water or seawater. A 30 turns, 160 mm diameter coil is prepared. We put the coil used as a resonator in a waterproof sealed case, and the coil is resonated and tested. From experiment results, we achieved 80mm WPT and transmitted 6 W. Frequency around 0.85 MHz is suitable for undersea WPT. We experimentally found that the optimal thickness of the air gap between the coil in the waterproof case and the wall surface of the case is around 20 mm.
In recent years, interest in energy harvesting is increasing with the increase of demand of energy and the consideration of the environment. Variety of technologies of energy harvesting have being developed by many researchers. One of them is a technology of electric power generation using the piezoelectric material. Authors have proposed the flexible piezoelectric device (FPED), which consists of a piezoelectric material and an elastic substrate such as rubber, silicon and resin, and have been developing the power generation technology using the FPED, which utilize renewable energy. An issue of the piezoelectric energy harvester and FPED is that the power generation frequency band is narrow. In this paper, a study of FPEDs connected by spring to broaden the power generation frequency band is presented. A forced vibration experiment has been conducted using a power generation system consist of FPEDs connected by spring, and the results show that the maximum power generation and the frequency band are improved by using a spring. A theoretical calculation method is also presented, and its validity is confirmed through comparison of the result by the presented method and the experimental results.
A three-dimensional force measurement instrument is designed and developed by considering the basic principle of zero compliance mechanism. In the proposed system, the point of force and the detection point are connected in series and suspended with leaf springs. One of the suspensions operates to cancel the displacement of the other. If any force is applied at point of force that causes displacement, the detection point displaces proportionally to cancel out the displacement of the point of force. As a result, zero compliance is achieved at the point of force and applied force can be measured from the displacement of the detection point. This paper presents the design and construction of a three-dimensional force measurement instrument and the effectiveness of the proposed system is demonstrated by the experimental result of the vertical-direction force measurement.
A compact active three-degree-of-freedom magnetic suspension system is fabricated which has a new configuration of magnetic poles. The fabricated magnetic suspension system has a differential structure consisting of an upper and a lower electromagnets. The electromagnet consists of four poles with coils and a single common pole whose opposite plane of the floator has a permanent magnet to achieve zero power control. Modal control is applied because local zero power control may make the whole system unstable when the number of control channel are larger than the number of freedom of motion to be controlled. The system parameters of each mode are identified experimentally to design the modal control system. The characteristics of the fabricated magnetic suspension system are studied experimentally.
Author proposes mass production structure of magnetostrictive vibrational power generator for battery- free IoT. This is based on a lamination of Fe-Ga alloy and a magnetic material (part), with a coil wound. This lamination is formed as a part of a U-shaped frame yoke with a permanent magnet attached. The magnetic part has moderate rigidity and is in a state of magnetic saturation. When the lamination is bent by an external force, the uniform stress generated in Fe-Ga changes the magnetic flux due to the Inverse magnetostrictive effect, and electromotive force proportional to time differential of the interlinking magnetic flux is generated in the coil. Compared with our conventional parallel beam type, the number of turns of the coil can be increased more than twice, and the assembly is easy and durability is high. The prototype using a Fe-Ga plate of 4 x 0.5 x 16mm3 generated maximum power of 1 mW at 28.4 Hz and 0.075 G vibration, and succeeded wireless signal transmission with one free vibration.
Thin steel plates are generally conveyed while in contact with rollers in the conveyance process. This leads to deterioration in the quality of the plate surface, such as flaws and peeling of the plated layer. The researchers in our laboratory have been involved in examining noncontact magnetic levitation control of the conveyance of a rectangular thin steel plate. We proposed hybrid electromagnetic levitation system which consists of electromagnets for levitation and horizontal positioning control and permanent magnets. In this study, the gap, number and optimal position of permanent magnets for suppressing the displacement of a magnetically levitated thin steel plate were investigated using thin steel plates by genetic algorithm. After that we examine effectiveness of optimal position of permanent magnets.
This paper describes a new structure for noncontact tilting floatation of an aluminum (Al) frame utilizing the AC ampere force given by the outer product of AC current in the Al frame and AC magnetic flux. It is hard to generate sufficient levitation force by using the conventional AC induction force technique when the area for eddy current to flow in the frame is not enough. On the other hand, the proposed structure applying the AC Ampere force technique achieved completely the tilting floatation of the Al frame under the condition that the secondary current flows along the frame regardless of through slits in the frame.
This paper presents a novel disk-shaped single-drive bearingless motor. The rotor is actively positioned only in the axial direction whereas it is passively stabilized in the radial and tilting directions. Generally, the rotor shaft length should be larger than the outer diameter for the passive stabilization in the tilting direction. On the other hand, the proposed bearingless motor has a large outer diameter and a short axial length with positive tilting stiffness. In this paper, the novel concept of the new machine structure is presented. In addition, the magnetic suspension force and rotational torque are calculated in three-dimensional finite-element-method analysis.
This paper presents the newly proposed heating method names as “Secondary Current Heating Method” to reduce the iron loss on laminated electrical steel sheet cores for high efficiency electrical motors. It is well known that the magnetic properties of electrical steel sheets, which are used for electrical motor cores, are deteriorated by the residual stress during manufacturing the electrical motors, and then the iron loss of the laminated electrical steel sheet cores of the electrical motors increases inevitably. The newly proposed Secondary Current Heating Method can improve the magnetic properties on laminated electrical steel sheet cores and reduce the iron loss of them in the very short time in comparison with conventional methods. In this paper, the electromagnetic and heating characteristics of the specimens by proposed method were confirmed, and then it was applied into the laminated ultrathin electrical steel sheet cores for high speed motors to reduce iron loss.
Recently, the majority of artificial hearts have been no pulsatile types. However natural hearts are pulsatile, and the long-term biocompatibility of the no pulsatile types has not been confirmed. We developed a linear actuator that can expect to be applied to pulsatile artificial heart. This linear actuator was applied to a pulsatile pump. It consists of power transmission, tanks, and permanent magnets. We propose a structure to reduce power consumption by a spring. Reduction in power consumption makes possible to downsize the entire apparatus. We developed such a linear actuator for pulsatile pump. In addition, we applied it to the electromagnetic pump and evaluated the basic structure and characteristics from the experiment.
In this project, we developed outer rotor type in-wheel motor. It was confirmed that there was no problem in the structure of motor by water resistance test, dust test and salt spray test. Due to the effect of adding fins on the motor case and reducing the current density, it can be driven at 15 kW without cooling for 1 hour on the motor bench, the temperature rise was less than 110 °C. As a result, the heat resistant class of the motor is classified H class in TRIAS. It was confirmed that there was practicality even without cooling by driving tests using vehicles equipped with developed motors on expressways and uphill gradients.
This paper proposes an electromagnetic induction type vibration generator using permanent magnets and coils. This proposal aims to improve the electromotive force by continuously moving the magnets and coils in opposite directions to increase the time rate of change of the magnetic field. To realize this continuous and opposite movement, a configuration using a “scissors type link mechanism” was examined. Furthermore, magnetic circuits, consisting of a magnetic flux around each cell of coils, were also used in conjunction to improve the electromotive force. A prototype implementing both of these characteristics was created to verify the actual effect of this configuration on its electromotive force and the generated magnetic attraction.
We developed a permanent magnet (PM) repulsive type magnetic levitation (maglev) system that supports a ring permanent magnet with extremely low magnetic stiffness in a noncontact manner. In this system, the ring permanent magnet is supported with a stiffness of only 19.6 N/m in the levitation direction. A sensor assembled with four Hall-ICs linearly detects a change in magnetic field associated with the motion of a levitated ring PM, and four air core coils control the magnetic field distribution in the space around the PM. These components actively stabilize the horizontal translational motion of the levitated ring PM. Our aim is to apply this device to micro mass measuring instruments and high sensitive vibrometers.
In order to construct a system with multi-degree of freedom by only using the motors with one degree of freedom, the same number of motors as the degree of freedom is required. On the other hand, in a spherical motor with three degrees of freedom, it is possible to realize a system with three degrees of freedom by only one spherical motor, and it is possible to reduce the size of the system. However, in many spherical motors driven by electromagnets, a spherical speed reducer is required as a device to extract and transmit the output torque. The spherical speed reducer considered in this study is composed of an output ball and two small balls transmitting torque. Each of the small balls is supported by two small ball casters. The mechanism of the spherical speed reducer requires a model of rotation transmission to control suitably the rotor for a desirable rotation of the output ball. The purpose of this study is to measure angular velocities of the small balls in the case that the output ball is not mounted as the first step to derive a rotation transmission model. From the measurement results, the arrangement of two small ball casters is focused on, and a valid rotation transmission model is derived.
Co-rich Fe-Co alloy with Co content of 66~75at% is known to have the potential of large saturation magnetostriction, high Curie temperature, high strength and good mechanical workability, however, its properties of thin plate and fine fiber below 1mm thickness remain unknown. Therefore, microstructure, magnetization and magnetostriction of the rolled Fe30Co70 alloy thin plate of 0.05mm in thickness were investigated. Crystalline microstructure becomes very fine and complicated due to the heavily deformation by the rolling process repeated many times at room temperature. Those morphology changes were investigated by the profile figures of XRD and SEM-EBSD/OIM analyses. The increases of magnetostriction value and its sensitivity were confirmed especially in the cold-rolled and subsequently annealed alloy plates. On the other hand, the coercive force decreased by decreasing the internal defects such as residual stress, dislocation density. These results will become useful for small magnetostrictive stress sensor and vibration energy harvesting device in considering of magnetostrictive composite materials for infra-structure health monitoring (SHM).