This project has been established between January 2008 and December 2012 on “Construction of Development Technology of Next Generation Applied Electromagnetic Machinery in Japan”, which is development of next generation applied electromagnetic machines upgrading high efficiency and new system such as a magnetic gear, magnetic dumper, magnetic bearing, etc. The fundamental seed technology is vector magnetic characteristic technology and its evaluation systems. This project has been finished on the end of 2012.
Output power of industrial servo motor is increased by intensifying magnetic flux density in the air gap. The magnetic-material-attached magnetic-flux-concentrated permanent magnet (MFCPM) array is a magnet array which can easily generate much larger magnetic flux density than the conventional magnet arrays, such as, ring-shaped SPM array, and Halbach array. This paper reports on prototype motor evaluation results when applying the MFCPM array. After three prototype design-and-evaluation steps, it is confirmed that, in comparison to the standard motor, the final prototype motor will perform more than 140% torque-mass density and over 600% power rate density with 62% motor mass.
Linear motors can achieve much higher speed, quicker response, and more accurate positioning than ball screws. To achieve higher response in the linear motor positioning systems, force density and power rate in the linear motor characteristics must be improved. Therefore, it is important to know how to increase the magnetic and electric loading for the downsizing design of electrical machines. We have been studying high-density machine designing since we proposed a permanent magnet mover utilizing the magnetic flux concentration type surface permanent magnet array (CSPM array) for linear synchronous motors. To improve the linear motor performance utilizing the CSPM array, we have employed a CSPM array combined with the electrical steel sheets in mover and optimized the construction by means of the three-dimensional finite element method. This paper presents that the prototype model has a higher potential for use in the linear motor positioning systems.
In recent years, the precise magnetic properties of electrical steel sheet are needed to develop high efficiency electromagnetic devices. An IEC standard single sheet tester is often used for magnetic property measurement, especially for commercial transactions. But it is not proper for the material evaluation based on its precise properties data. Therefore, we developed measurement techniques for the precise magnetic properties of electrical steel sheet. In this paper, the key technology for evaluation of electrical steel sheet is proposed. The single sheet tester based on evaluation measurement technique is useful for adequate choice of electrical steel sheet for high efficiency electrical devices and evaluation of high performance power magnetic materials, etc.
This paper presents iron loss distribution measurement technology and local vector magnetic distribution measurement technique applied to a permanent magnet motor. In the iron loss measurements, we used a V-H sensor in order to obtain local vector magnetic property distributions. In this paper we describe the measurement principle and provide an overview of the measurement system. Effects of stresses induced by welding and locking pins in the stator yoke on the magnetic properties are made clear and influence of the magnetic anisotropy due to rolling is identified. Furthermore we describe a measurement principle and a measurement system based on a thermographic camera. This system was also applied to obtain iron loss distributions in a stator core. From these measured results, the local iron loss characteristics in the permanent magnet motor cores are clarified.
We have reported measured results of magnetic properties of a non-oriented electrical steel sheet under various magnetic flux and stress conditions. In this paper, the influence of the uniaxial and biaxial stress on the vector magnetic properties and magnetic power loss are examined in detail. As an application of electrical machine design, a permanent magnet motor is analyzed by using complex-approximated vector magnetic characteristic analysis and the measured database. As a result, the magnetic power loss of the stator core in the permanent magnet motor is decreased by applying an in-plane tensile stress.
This paper presents results of torque characteristic analysis of magnetic flux concentration type surface permanent magnet synchronous motors (CSPMSMs). In this study, we firstly optimized numerically the stator structure to find out suitable number of slots for the conventional 12-pole CSPM rotor by using the finite element method. Then the rotor permanent magnet arrangements were examined in order to improve the torque characteristic. In the optimized model, we achieved larger average torque and smaller cogging torque in comparison with those of the conventional CSPM motor.
In order to address the signal integrity issue, Galilean electromagnetism is derived from a thermodynamic approach. Attention is paid on the various regimes allowed by the quasi-static limit. It is emphasized that an abrupt transition exists between the QS-magnetic and the QS-electric regimes for which different gauge conditions on the potentials should be considered.
This paper presents magnetic properties of permanent magnet wires developed for applications of micro magnetic actuators. Nd-Fe-B and Sm-Co permanent magnets have been contributed to improve efficiency of electrical machines and magnetic actuators and to miniaturize their size and weight. Recently use of Nd-Fe-B based permanent magnets in micro machines is also paid attention to improve moving performance such as increasing torque and reducing energy losses. Our target is producing a 0.2mm diameter wire-shaped permanent magnet directly by using a spinning method in rotating liquid for a medical application. In this paper, the magnetic properties of Nd-Fe-B and Sm-Co based permanent magnet wires developed with different nozzle orifice size (0.1 mm, 0.2 mm and 0.3 mm in diameter) are discussed. The result shows that the coercive force of the wire samples made by using the nozzle whose orifice sizes is 0.1 mm was improved
This study discusses the vibration characteristics of the magnetic spring vibration-isolating bed which is used in ambulances. Ambulances can operate at a maximum speed of 80 km/h, and often accelerate and decelerate at various speeds. These driving conditions cause blood pressure fluctuation and resonance of internal organs of patients riding in ambulances. Therefore, vibration isolation is needed to prevent patients from experiencing the vibration caused by ambulances. In this bed, both a nonlinear magnetic spring and linear springs (torsion bars) are set between the mount and the bed in parallel, and achieve the nonlinear Duffing-type restoring force characteristics of the springs. By setting the spring constant of the magnetic spring as negative, the total spring constant becomes approximately zero, which can isolate patients from the vibration of an ambulance. In this research, an experimental and analytical evaluation of the vibration-isolating bed for ambulance was performed, and the optimum design for the suspension system is proposed.
New magnetic functional fluids containing both of nanometer-size needle-like magnetic particles and micrometer-size spherical magnetic particles are produced and its damping properties are investigated experimentally by using a simple prototype damper. Damping force is variable by changing intensity of applied magnetic field. Damping property of the damper depends on mixture ratio of nanometer-size magnetic particles to micrometer-size magnetic particles. Higher ratio of volume fraction of needle-like magnetic particles against that of all particles increases the damping force; in contrast higher ratio of volume fraction of nanometer-size magnetic particles against the total volume fraction of particles in a magnetic compound fluid decreases the damping force. In the absence of magnetic field, the fluid behaves like a Bingham fluid, while the fluid can be treated as a pseudoplastic fluid in the presence of magnetic field.
The determination problem of optimum position and shape of exciting coil and teeth of LIM-type electromagnetic stirrer is discussed. 3-D magnetic field FEM analysis and Rosenbrock's method are used. Design guidelines for minimizing power capacity and maximizing flux density are examined using the objective function, that is the inverse of evaluation factor including the flux density at a specified position and load inductance. It is shown that the coil position affects mostly the performance of stirrer.