Semi-hard magnetic materials, which can retain magnetization when excited by pulsed currents, are promising for reducing power consumption in electromagnetic components. In this study, we developed low-alloy semi-hard magnetic steels optimized for solenoid devices such as electromagnetic clutches and brakes. The materials were designed considering not only magnetic properties but also machinability and cost. The developed materials exhibit high remanence and moderate coercivity, enabling stable magnetic holding without continuous current supply. Their effectiveness was demonstrated through electromagnetic analysis and prototype evaluations, showing significant reduction in power consumption.

抄録全体を表示

variable magnetomotive force memory motor (VMFM) is a motor that can expand its operating range by changing the magnetization state of a variable permanent magnet. However, changing the magnetization state requires a pulse current several times larger than the armature current rating. This paper proposes a method using magnetization coils in the stator to reduce the magnetization current in each power semiconductor device for VMFM. The proposed VMFM is equipped with magnetization windings in addition to the three-phase drive windings on the stator teeth, and the magnetization windings are connected in parallel with the drive windings and powered by the same inverter. By turning ON all three upper or lower arms simultaneously, the magnetization current per device can be limited to one-third of the inverter rating. Magnetic field analysis confirmed that the proposed VMFM satisfies target load points that the base PMSM cannot reach, demonstrating that a small device and low cost can be achieved while maintaining manufacturability.

抄録全体を表示

In this paper, a variable-magnet permanent magnet vernier motor (PMVM) is proposed to achieve high-efficiency operation over a wide operating range, from low-speed/high-load to high-speed/low-load conditions, by switching between PMVM and permanent magnet synchronous motor (PMSM) modes within a single motor.

抄録全体を表示

A single-degree-of-freedom mechanical system composed of mass, stiffness, and damping elements exhibits a resonant response characterized by a peak at its natural frequency and a Q factor determined by these parameters. While high-Q resonance enables high gain in applications such as vibration actuators and energy harvesters, it also narrows the operating bandwidth and increases sensitivity to parameter variations. To overcome this trade-off, the author developed a broadband vibration device that switches its degrees of freedom using an electropermanent magnet (EPM), achieving broadband operation without directly tuning mechanical parameters.

抄録全体を表示

This paper presents an inchworm-type locomotion mechanism employing electropermanent magnets (EPMs) as position-holding devices for energy-efficient motion. The proposed mechanism consists of multilayered piezoelectric actuators and EPM-based holding units arranged in a delta configuration, enabling planar motion with translational and rotational degrees of freedom without guide mechanism. Locomotion is achieved by sequential activation of piezoelectric elements and switching of the EPM holding states, realizing stepwise movement based on the inchworm principle. Since electrical power is consumed only during the magnetization and demagnetization switching of the EPMs, the proposed system reduces energy consumption compared to conventional electromagnet-based mechanisms. Experimental evaluations demonstrate stable linear and rotational motions and confirm the effectiveness of the EPMs in maintaining sufficient holding force while achieving low power operation. The proposed mechanism is suitable for applications requiring precise positioning and long-term operation with minimal energy consumption.

抄録全体を表示

Magnetic clamps are gaining popularity as a new technology to replace conventional manual and hydraulic systems, aiming to improve the efficiency and safety of mold changes. In particular, the advantages of reduced environmental impact, energy efficiency, and a design that does not require standardization are discussed.

抄録全体を表示

This study investigates the influence of rotor position on the local vector magnetic property of a three-phase induction motor model core through experimental measurements. A movable measurement system was developed to automatically rotate the rotor core and measure the magnetic flux density and magnetic field strength vectors at 1° intervals. The results show that, in the tooth region, the maximum magnetic flux density exhibits periodic variation corresponding to the number of rotor slots. This behavior indicates that the periodic change in magnetic reluctance between the stator and rotor significantly affects the local magnetic properties. Furthermore, the behavior of B and H vectors is investigated using the vector magnetic analysis software μ-E&S.

抄録全体を表示

In industrial applications, conventional mechanical gears are widely used but suffer from wear, lubrication requirements, and noise due to mechanical contact. In contrast, flux-modulated magnetic gears transmit torque without contact, offering advantages such as maintenance-free operation, low noise, and high reliability, making them promising for next-generation power transmission systems. Nevertheless, several issues remain unresolved, including loss of synchronization under high load, temperature rise during prolonged operation, and demagnetization of permanent magnets. These phenomena can significantly affect system performance and reliability and are key obstacles to practical implementation. They often emerge as complex transient behaviors during transitions from steady state to non-steady conditions, where multiple physical effects interact. Experimental studies that evaluate these non-steady behaviors in detail are still limited. This study investigates a prototype flux-modulated magnetic gear to evaluate transition phenomena such as loss of synchronization, heat generation, and demagnetization based on measured data. By analyzing torque transmission characteristics, rotational speed, and temperature variations, the mechanisms underlying non-steady behavior are clarified, providing insights beneficial for future design guidelines.

抄録全体を表示