Noboru Niguchi

Cogging Torque Analysis of Magnetic Gear

This paper describes the harmonic spectra of the cogging torque of a magnetic gear. The operating principle of this gear is described, and the transmission torque under operation in accordance with the gear ratio is mathematically formulated. In particular, the harmonic order of the cogging torque is described in detail. Moreover, the orders of the cogging torque of both rotors are verified by employing 3-D finite element method. The computed results are also then further verified by carrying out measurements on a prototype. Other harmonic components are observed in the computed and measured results, but it is discussed why they are contained in the cogging torque.

Transmission Torque Analysis of a Novel Magnetic Planetary Gear Employing 3-D FEM

This paper describes the transmission torque characteristics of a novel magnetic planetary gear. A hybrid-type magnetic planetary gear is proposed, and the operational principle is shown when it is operated as a star-, planetary-, and solar-type magnetic planetary gear. The dynamic transmission torque characteristics are computed by employing 3-D finite-element method, and lastly verified by carrying out measurements on a prototype.

Analysis of 2-Degree of Freedom Outer Rotor Spherical Actuator Employing 3-D Finite Element Method

To drive a conventional motor drive system, the number of degrees of freedom needed has to be equal to the number of actuators employed, and this causes the system to be larger and heavier. To solve these problems, the development of a spherical actuator which can rotate around multi axes is being conducted. In this paper, we propose a new spherical actuator with an outer rotor to produce higher torque density and describe the control method for open loop drive. Static torque and dynamic characteristics of the actuator are clarified by employing 3-D finite element method and are verified from experimental results of a prototype.

Cogging torque characteristics of magnetic‐geared motor

Purpose – The purpose of this paper is to propose a magnetic‐geared motor with permanent magnets only on the high‐speed rotor as a solution to the problems of magnetic gears. Magnetic gears have some advantages such as no mechanical loss and maintenance‐free operation that are not observed in conventional mechanical gears. Furthermore, they have inherent overload protection. A novel structure which the magnetic gear is integrated with the brushless motor (magnetic‐geared motor) was proposed by Atallah et al. This magnetic‐geared motor is based on the magnetic gear which consists of a high‐ and low‐speed rotor, and a stator. Although this magnetic‐geared motor has a high‐torque density, problems with manufacturing and cost exist because multi‐pole permanent magnets are mounted on the high‐speed rotor and stator.Design/methodology/approach – A magnetic‐geared motor with permanent magnets only on the high‐speed rotor was proposed and its operational principle was described. The cogging torque characteristics...

Transmission torque characteristics in a magnetic gear

This paper describes the transmission torque characteristics in a surface permanent magnet-type (SPM-type) magnetic gear. The operating principle of this gear and its transmission torque under the synchronous operation in accordance with the gear ratio are formulated. And the high-order components contained in the cogging torque are verified by employing the 3-D finite element method (FEM) and carrying out measurements on a prototype. Furthermore, a method for reducing the cogging torque is discussed.

Torque-Speed Characteristics Analysis of a Magnetic-Geared Motor Using Finite Element Method Coupled With Vector Control

This paper describes the torque-speed characteristics of a magnetic-geared motor with permanent magnets only on the high-speed rotor. This magnetic-geared motor has inherent overload protection characteristics, and the rotor slips under overload condition. The characteristics are determined by using finite element analysis under vector control. The analysis results are then verified by carrying out measurements on a prototype.

Continuously Variable Speed Vernier Magnetic Gear

This paper presents a magnetic gear whose gear ratio (ratio of output speed to input speed) can be continuously varied. Although it can be used anywhere, we feel it would be best utilized in wind power generation due to its virtually maintenance free operation and inherent overload protection characteristics. Furthermore a continuously variable gear ratio would allow for the generator to constantly rotate at its most efficient speed regardless of the wind speed. The equation governing the relationship between high speed rotor, low speed rotor and frequency of the 3 phase AC supply is mathematically formulated and confirmed using FEM analysis.

Magnetic-geared motors with high transmission torque density

Purpose – Early magnetic-geared motors have a high transmission torque density. However, the torque due to the coil is low because the permanent magnets in the stator become a large magnetic resistance when the current is applied to the coil. The purpose of this paper is to propose magnetic-geared motors which have a high transmission torque density and torque due to the coil. In addition, the proposed magnetic-geared motors are compared with past magnetic-geared motors and the effectiveness is verified by using finite element analysis. Design/methodology/approach – A new magnetic-geared motor which has permanent magnets in the stator slot are proposed. The torque due to the coil increases by removing permanent magnets at the tip of the stator of past magnetic-geared motors. The permanent magnets placed in the stator slots are all magnetized to the outward direction and then the stator teeth are all magnetized to the inward direction. The maximum transmission torque and torque constant are compared. Findi...

Permanent magnet assisted current superimposition variable flux machine

Electric and hybrid electric vehicles require traction motors that have a high power and efficiency over a wide rotation speed range . In order to satisfy these requirements and reduce the motor cost, variable flux reluctance motors (VFRMs) have been studied . Conventional VMFRMs have DC-field windings and armature windings. However, because there are two kinds of windings, the coil space factor decreases and the wiring becomes complicated . In order to solve these problems, we have developed a motor called the variable flux reluctance motor (CSVFRM) that does not have any DC-field coils, and instead uses current superimposition . In this paper, we propose a modified model whereby permanent magnets are introduced into the stator to increase the efficiency . The structure and operational principle of this machine are described and the N-T characteristics are computed by FEA.

Experimental Verification of Feedback Control of a 2-DOF Spherical Actuator

To drive conventional motor drive systems that have multiple degrees of freedom (DOF), such as industrial robot arms, the number of actuators employed has to be equal to the number of DOF. This causes the system to be large and heavy, and also have a lower overall efficiency. To solve these problems, the development of spherical actuators, which can rotate around multiple axes, is being conducted. In general, multi-DOF actuators have many poles and coils, and the currents of the coils have to be controlled individually, making the control system complicated. In this paper, we propose a feedback control method for a 2-DOF actuator that enables the currents of the coils to be easily determined. The effectiveness of the control method is verified through experimental verification.