Magnetic gears have several advantages such as having low acoustic noise and being maintenance-free because there is no mechanical contact. Among these gears, the flux-modulated type has a higher torque density and efficiency than the other types. Therefore, it is expected to be put into practical use. In previous papers, a spoke-shaped interior permanent magnet (IPM) rotor structure was proposed in order to reduce the eddy current loss in magnets. This paper presents three methods for improving the performance of the spoke-shaped IPM magnetic gear. First, the position of the magnetic bridges is changed from the air gap side to the back yoke side to increase the effective magnetic flux. Second, amorphous alloy is used for the rotor core and pole pieces in order to reduce iron loss. Third, bonded Nd-Fe-B magnets for canceling the leakage flux are arranged to sandwich the inner rotor from both sides. As a result of prototype tests, the measured maximum torque of the proposed spoke-shaped IPM magnetic gear was 44% higher than that of the conventional one. In addition, the measured maximum efficiency reached 99.85% at 100 rpm.

  In recent years, it has been strongly required to reduce radiated noises from transformer cores used in electric power systems. The noises from transformer cores seem to be mainly caused by magnetostriction. Thus, it is necessary to establish a method for quantitatively calculating the force generated from the magnetostriction (magnetostriction force) with not only high-accuracy but also high-speed. This paper presents that the magnetostriction force is calculated based on a reluctance network analysis (RNA) by using a simple-shape wound core as an object of discussion. The validity of the proposed method is indicated by comparing with calculation results obtained from a finite element method (FEM).

  The temperature difference ΔT and the thickness dependences of the spin See beck voltage (V_SSE) were investigated for the polycrystalline BiY₂Fe₅O₁₂/Pt device made by metal organic decomposition method. As a result of investigation of the ΔT dependence of V_SSE, it was shown that the coercivity of V_SSE largely changed at the certain temperature difference ΔT_g, and ΔT_g was decreased with the thickness of BiY₂Fe₅O₁₂ thin film increases. When ΔT>ΔT_g, the coercivity of V_SSE was almost the same as the coercivity of magnetization curve for the BiY₂Fe₅O₁₂/Pt device. On the other hand, when ΔT<ΔT_g, the coercivity of V_SSE was about twice as the coercivity of V_SSE when ΔT>ΔT_g. Focus attention on the remanence of V_SSE which the gap occurs in the coercivity of V_SSE is almost constant independently of the thickness of BiY₂Fe₅O₁₂ thin films.

  The effect of light elements such as B, C and N on Sm(Fe_0.8Co_0.2)₁₂ alloy was investigated in detail. The highest coercivity H_c of 11.1 kOe was obtained for Sm(Fe_0.8Co_0.2)₁₂-B thin films with the thickness of 100 nm and B content of 11.2 at.%. From X-ray diffraction patterns, peaks from (002) and (004) of ThMn₁₂-type phase were clearly observed for the films. However, no significant improvement in magnetic properties was observed with the addition of C and N to the Sm(Fe_0.8Co_0.2)₁₂ alloy, as was the case with the combined addition with B. It was confirmed that only the addition of B contributes significantly to the improvement of magnetic properties from the result of adding light elements to this series of Sm(Fe_0.8Co_0.2)₁₂ alloy.

  Many kinds of servers for communication base stations are being installed to provide information technology (IT) services. Hence, the servers require not only high-performance processer but also their cooling system. Among the cooling systems, a cooling fan is the most suitable due to good balance between performance and cost. Nowadays, the cooling fans are required to be improved the cooling performance and efficiency because the heat generation in servers is increased. In a previous paper, several cooling fan motors are designed and compared each other. As a result, an interior permanent magnet (IPM) motor with the magnets equally divided in the circumference direction has the highest efficiency. This paper presents prototype test results of the proposed IPM motor, which are compared to the calculation results. Next, stray losses caused by eddy current and harmonic current are investigated by using three-dimensional finite element method (3D-FEM).