Hitachi Engineering (Japan)

SUMMARYThis paper proposes a construction method for battery systems that are widely used in industries. The battery system uses a building block structure combined with a battery module, whose capacity is less than 1 kWh. To manage the building block structured system, we propose a hierarchical structured management method. In each hierarchy, the voltage and temperature of the battery are monitored, and the information necessary for calculating charge states and detecting faults are sent to the upper hierarchy for the state management of the lower hierarchy. Furthermore, to ensure the safety during maintenance activities, we provide a guidance for understanding the insulation structure for the battery module, and develop a ground fault detection method that detects a decline in the insulation performance by using a rising method. For the experiment, we use a 30‐kWh trial manufacture battery system combined with the hierarchical management method. We verify that charge states and faults are detected in the battery of the system, and confirm that the system can be charged and discharged safely.

Penelitian ini bertujuan untuk mengetahui pengaruh jenis bahan, temperatur, dan kecepatan tool expander terhadap deformasi plastis material yang terjadi pada proses Tube Expanding. Hasil pengujian menyatakan bahwa deformasi yang paling kecil terjadi pada material Baja Stainless Steel ASTM A 249 Grade 2 dan temperatur tube expanding yang paling optimal terjadi pada temperatur 89,6 derajat Fahrenheit. Sedangkan kecepatan tool expander yang paling optimal saat deformasi terjadi adalah 0,708 inch per second.Tahapan-tahapan penelitian yang dilakukan adalah studi literatur berdasarkan penelitian terdahulu, mengambil data dari bagian Engineering dan Production Planning Control PT.BBI Pasuruan, melakukan simulasi pengujian dengan menggunakan Deform 3D, Â menganalisa data memakai Design Of Experiment Taguchi Method, serta menarik kesimpulan.Hasil analisa dimanfaatkan sebagai bahan rekomendasi untuk perbaikan proses Tube Expanding di bagian Engineering dan Production Planning Control PT.BBI Pasuruan.

SUMMARYWe designed a miniaturized permanent magnet synchronous motor with a magnetic gear by using an optimal design technique based on thermomagnetic field coupling analysis. To construct an even smaller motor, investigating the heat dissipation from the motor and increasing its rotation speed are necessary. We manufactured and tested the designed motor with a magnetic gear. The measured torque and motor efficiency demonstrated the high precision of the proposed design.

In this paper, we propose a new sensorless control method using the neutral point voltage of stator windings. Each inductance of the three phase coils of the permanent magnet synchronous motor (PMSM) is slightly changed by the rotor magnet flux. As a result, the neutral point voltage also changes depending on the rotor position. According to this principle, the rotor position can be estimated by detecting the neutral point voltage, even in the zero speed region. We implement this technique and show the experimental results.

We developed a method for calculating the displacement of the beam spot focused on an optical disc by the objective lens for optical pickups. This method is reasonably accurate at predicting the stability in tracking servo control systems. The vibration model of an optical pickup is expressed as the frequency response function of the ratio of the displacement of the beam spot focused on an optical disc by the objective lens to the voltage applied to the tracking coils. The displacement of the beam spot was obtained by adding the product of the focal length of the objective lens and the incident angle of the beam onto the objective lens caused by mirror rotation to the displacement of the objective lens. The calculated values agree well with the measured results. Stiffening the pickup case around the mirror could help to decrease the displacement of the beam spot on an optical disc by 40%.

A straightforward solution for minimizing the cost of major materials used in motors, such as permanent magnets and silicon steel sheets, is to reduce the motor size as far as possible. However, there is a trade-off between the motor size and temperature rise in the motor that should be taken into account while reducing the motor size. For achieving this, we have been developing an optimal design method based on a combination of a thermo-magnetic field coupling analysis and a direct search algorithm. This paper reports the details of this design method. An outer-rotor, multipole permanent-magnet synchronous motor is the test motor. The results of the torque-density-maximization problem involving constraints on the terminal voltage, coil-temperature rise, and demagnetization of the magnet are shown. The usefulness of our method is also demonstrated.

For the stabilization of insulation performance in resin-molded insulators, strong adhesion between the resin and ceramic is required. In this paper, a new technique for the control of the interfacial strength in resin-molded structures has been proposed. The adhesive strength of the internal interface in a resin-molded structure was estimated as the interfacial fracture energy by using the molecular dynamics method. The interfacial fracture energy was qualitatively in agreement with the adhesive strength index obtained by a shear experiment. Based on the simulation results, the control of the interfacial strength was performed, and it became clear from the result that the interfacial strength between resin and ceramic can be improved up to the strength level of the glaze adhesion.

To evaluate tin-whisker growth during thermal cycling tests, a simulation technique for calculating the change in atomic-density distribution of tin caused by a change in temperature, which induces a stress gradient in polycrystalline tin plating, was developed. This technique uses the finite-element method (FEM), molecular-dynamics (MD) simulation, and X-ray diffraction (XRD). Specifically, an FEM model was used to simulate stress-induced diffusion, including grain-boundary diffusion, in a tin coating on copper leads by using the stress- and mass-diffusion-analysis function of commercial FEM software. The stress analysis model considered elasticity anisotropy, thermal-expansion anisotropy, and crystal orientation of β-tin. Crystal orientations were assigned to tin grains in the model according to reference XRD measurements. Diffusion coefficients for the mass-diffusion analysis were calculated by MD simulation. Two models with different crystal-orientation distributions were evaluated. Samples with a higher tin atomic density were found to be more likely to have longer tin whiskers and higher whisker density. It is concluded from these results that the tin-atomic-density distribution calculated with this model can be used as an effective indicator of the propensity to form tin whiskers.

Photocatalysts cleaning dishwater have been studied to high performance. A fluid bed for cleaning dishwater is efficient to contact between photocatalytic particles and dishwater. However, submicron photocatalytic particles are difficult to collect and recover in the fluid bed. This paper presents photocatalytic composite particles in the fluid bed for cleaning dishwater. The developed photocatalytic composite particles consist of floating resin particles covered with photocatalytic particles (TiO2). The efficiency of the photocatalytic composite particles is occurred with an examination of concentration changes in organic dye (Rhodamine B) solution. As a result, after 90min the concentration of Rhodamine B is decreased to 10%. The reaction of Rhodamine B molecules was 2 steps reactions. 1st step was absorption on a surface of metal on photocatalytic particles, and 2nd step was displacement reaction by photocatalysis. Consequently, Rhodamine B molecules were reacted to Florescein molecules by the photocatalytic composite particles.

The fixed conditions of butt welds between straight pipe and the valves or pump in an actual piping system are different from those of straight pipes. However, the effect of the fixed condition on the residual stress and the stress intensity factor for the evaluation of the structural integrity of cracked piping is not clear. In this study, finite element analyses were conducted by considering the differences in the distance from the center of weld to the fixed end L, to clarify the effect of the fixed condition on the residual stress and the stress intensity factor. For 600A piping, the residual stress distribution was not affected by L. Furthermore, the stress intensity factors of circumferential cracks under the residual stress field can be estimated by using an existing simplified solution for piping.