Disk-type Rotor Research Articles

Research on a Novel Transverse Flux Permanent Magnet Motor With Hybrid Stator Core and Disk-Type Rotor for Industrial Robot Applications

Traditional surface permanent magnet synchronous motor (SPMSM) used as a servo motor limits the miniaturization and performance improvement of industrial robot, due to its large overall volume and heavy weight of the rotor. In this article, a novel transverse flux permanent magnet motor with a hybrid stator core and disk-type rotor (HSDR-TFPM) is proposed to adapt to the industrial robot well. Moreover, a better space design by which the usual components used in industrial robot is considered. Considering the computing time and accuracy, an analysis method based on Schwarz-Christoffel mapping is employed to analyze the magnetic field of HSDR-TFPM and conduct research on motor parameters. In order to prevent the axial movement of rotor, the detailed mechanical design is introduced and the strength of motor is analyzed further. In the end, the analysis results and performance of the proposed HSDR-TFPM are validated and compared with a conventional servo SPMSM.

Application of Frequency-Following Servocompensator to Unbalance Compensation in Gyro With Flexures Gimbal

A frequency-following servocompensator is applied to a rotary gyro with flexures gimbal to eliminate the oscillating components from the estimated signals. In the targeted gyro, a synchronous motor is fixed to a rectangular holder and a disk-type rotor is driven by the motor to generate gyroscopic couplings. The coupled two rotational motions of the holder are controlled by four electromagnets on the stator; the angular velocities are estimated from the control currents to regulate the relative displacement of the holder to the stator. The other four-degree-of-freedom motions of the holder are constrained by the flexures gimbal. Such suspension using flexures makes the system less damped so that high accuracy is expected to this gyro. However, one of the problems is that an oscillating component caused by rotor unbalance appears in the estimated signal because the estimation is based on the control input. To solve this problem, the frequency-tracking servocompensator is applied to eliminate the oscillating component. The virtually perfect elimination of the component from the estimated signal was achieved.

ハイブリッド支持式回転型ジャイロの開発

A new configuration for rotating gyros using magnetic suspension is proposed and fabricated. Gyro is one of inertial sensors and a measuring instrument for angular velocity. The magnetically suspended gyro (MSG) was proposed in which a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the holder; the holder is suspended by magnetic force without any mechanical contact to achieve high-accuracy measurement. According to this concept, a six-degree-of-freedom (6-DOF) active MSG was developed. However, the MSG had to consume power for compensating the gravitational force acting on the holder by magnetic force. In addition, the miniaturization of the MSG was difficult because four pairs of electromagnets were arranged on the opposite sides of the holder. To solve these problems, a novel gyro with hybrid suspension is designed and fabricated. In this gyro, only two rotational motions of the holder are controlled by four electromagnets while the other 4-DOF motions of the holder are constrained by cross springs and a gimbal. Such configuration is suitable for reducing power consumption and also for miniaturization. This paper shows the basic concepts and measurement principles of the rotary gyro with hybrid suspension. The performance of the gyro is evaluated through the measurement of two-axis angular velocities. It is found from the measured frequency characteristics and the succeeding analysis that imperfect derivatives used in the estimation cause an interaction between the two-axis estimations. Two ways to cope with this problem are also presented.

Development of a totally active magnetically suspended gyro

A magnetically suspended gyro (MSG) is developed and its performances is estimated. In the MSG, a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the frame of the floator. The floator is suspended by magnetic force without any mechanical contact so that highly accurate measurement is possible. In accordance with this concept, a three-degrees-of-freedom (DOF) active MSG was developed. However, because of poor damping in the passive suspension and the low resolution of the displacement sensors, the measurement accuracy was relatively low. To solve these problems, a six-DOF (totally) active MSG is designed and fabricated. The frame of this gyro is an octagonal. The motion of the frame is controlled by eight electromagnets. The performance of the gyro is evaluated through measurement of the double-axis angular velocity. The advantages of totally active suspension are investigated. Sufficient damping rapidly reduces the influence of disturbances. Then, the influence of sensor noise is examined. The results of this examination show that the accuracy of the angular velocity measurement is improved by using highly sensitive displacement sensors. Next, the dynamic range is measured. This experiment shows that the MSG can provide precise angular velocity measurement in a low-frequency region.

Application of Unbalance Compensation to a Rotary Gyro with Hybrid Suspension

This paper presents an application of unbalance compensation to a rotary gyro with hybrid suspension. In this gyro, a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the frame of the holder. The four-degree-of-freedom motions of the holder are constrained by a cross spring and a gimbal. The two rotational motions of the holder are controlled by four electromagnets. Such hybrid suspension makes the system less damped. Therefore, high-accuracy measurement is possible by this gyro. However, one of the problems is that an oscillating component due to unbalance appears in the estimated angular velocity because the estimation is based on the control currents for regulating the relative displacement of the holder to the stator. To solve this problem, unbalance compensation is applied to remove the oscillating component. It is confirmed experimentally that the estimated signal agrees well with the reference signal.

Design and simulation of disk stepper motor with permanent magnets

Abstract In this paper the design and the magneto-static simulation of axial-flux permanent- magnet stepper motor with the disc type rotor is presented. Disk motors are particularly suitable for electrical vehicles, robots, valve control, pumps, centrifuges, fans, machine tools and manufacturing. The brushless machine with axial flux and permanent magnets, also called the disc-type machine, is an interesting alternative to its cylindrical radial flux counterpart due to the disk shape, compact construction and high torque density. This paper describes a design of four phase microstepping motor with the disc type rotor. The FEM modeling and the 3D magneto-static simulation of the disk stepper motor with permanent magnets is being subject of the article, too. Disc rotor type permanent magnet stepper motor for high torque to inertia ratio is ideal for robotics and CNC machines.

B11 2自由度制御型磁気支持小型ジャイロの開発 : 第1報:基本構想と測定原理(M-OS1-3:装置の開発と評価,M-OS1 磁気浮上・磁気軸受の制御,「海を越え,国を越え,世代を超えて!」)

A new configuration for rotating gyros using magnetic suspension is proposed in this study. Gyro is one of inertial sensor and measuring instrument for angular velocity. In a magnetically suspended gyro (MSG), a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the frame of the floator. The floator is suspended by magnetic force without any mechanical contact so that high-accuracy measurement is possible. According to this concept, a 6-degree-of-freedom (DOF) active MSG was developed. However, because the MSG used magnetic attraction pulling upward against gravity, it has high power consumption. In addition, the miniaturization of the MSG was difficult because four pairs of electromagnets were arranged on opposite sides of the floator. To solve these problems, a 2-DOF active magnetically suspended micro gyro (MSMG) is designed and fabricated. In this gyro, the 4-DOF motions of the floator are constrained by a cross spring and a gimbal. The two rotational degrees of motion of the floator is controlled by four electromagnets. The gyro with such configuration is suitable for miniaturization and low-cost fabrication. This paper shows basic concepts and measurement principle of the 2-DOF active MSMG.

21107 6自由度制御型磁気支持ジャイロセンサにおける測定感度評価(OS10-4【ロボティクス・メカトロニクス(4)】)

A six-degree-of-freedom (DOF) active magnetically suspended gyro (MSG) is developed and its performances are estimated. In MSG, a disk-type rotor is connected to a synchronous motor through fluid bearing, the motor is fixed to the frame and the frame is suspended by magneticforce without any mechanical contact; According to this concept, a three-DOF active MSG was developed. However, because of poor damping in the passive suspension and low resolution of displacement sensor, measurement accuracy was relatively low. To solve these problems, a totally (six-DOF) active MSG was fabricated. In this paper, the influence of displacement sensor noise on angular velocity measurement is examined. Since the totally active MSG's displacement sensor is more sensitive than the three-DOF active MSG's, the totally active MSG has less noise of measurement angular velocity than the three-DOF active MSG.

Vibration control of the high-TC superconducting levitation synchronous motor

In this research, we propose the high-TC superconducting levitation synchronous motor that the levitation, the drive, and the vibration suppression are possible with the single disk type rotor composed by some permanent magnets. The center of gravity position is low because this rotor is the single disk structure, and the pitching doesn't occur easily. The displ acement of the horizontal direction when the levitation rotor rotat es is measured with the laser displacement meter. And, the vibration is controlled by feeding back this whirling speed to an damper. The High-TC Superconducting Levitation synchronous motor with such a vibration suppression mechanism is developed, and utility is verified by the experiment. Motion analysis and the numerical analysis of the force of an damper were done.

Decoupled Control of a Disk-Type Rotor Equipped With a Three-Pole Hybrid Magnetic Bearing

Recently, there has been an increasing need for development of active magnetic bearing (AMB) systems of smaller size and lower energy consumption than ever, as AMBs seek for applications in compact, portable rotating machines such as hard disk spindle and artificial heart blood pump. Among others, the three-pole AMB configuration turns out to be more profitable in terms of compactness in design and low power loss than the conventional four- or eight-pole AMB. However, one of the inherent drawbacks in controller design of three-pole AMB is the strong coupling in magnetic flux between magnetic poles. It leads to the strongly nonlinear system behavior, when the equation of motion is formulated in the conventional Cartesian coordinates. In this paper, we propose use of the redundant bearing coordinates to describe the three-pole AMB system behavior, so that the potential difference controllers can be easily designed, based on the decoupled linearized control model for each pole. The proposed method is applied to control of a five-axis AMB system, which consists of a three-pole radial AMB for stabilization in the radial direction and a ring-type permanent magnet bearing for levitation in the axial and tilt directions. It is shown that simplistic equation of motion for the five-axis AMB system can be derived in the proposed redundant bearing coordinates and the resulting control equations become completely decoupled. Experiments are also carried out with the five-axis disk-type AMB system equipped with Hall diodes for measurement of the radial displacement and it is confirmed that the proposed control scheme succeeds in the run-up test.

Fundamental performance of triple magnetic circuit type cylindrical thermomagnetic engine

AbstractThe engine essentially consists of a rotor made of temperature‐sensitive magnetic material and permanent magnets. When an object made of this material has a temperature distribution in the magnetic field, the force is generated in the direction from the low‐temperature side to the high‐temperature side by magnetic pressure.This paper describes the fundamental performance of the triple magnetic circuit type thermomagnetic engine. A triple magnetic circuit type engine with water‐cooling system has ben designed. The performance characteristics such as power, resistance loss, and the relation between the temperature of the rotor and the rotation speed have been measured, and compared with the characteristics of a single magnetic circuit type engine. The net power is a maximum value of 3.7 W at a rotation speed of 0.4 rps. The power of the triple magnetic circuit type engine per unit magnetic circuit is about 4 times larger than that of the single magnetic circuit type engine. The resistance loss is 1.7 W at the maximum power point. The total power is 5.4 W. Electromagnetic braking loss is about 25% of the total power. The rate of electromagnetic braking loss to the total power increases with the rotation speed. The disk type rotor with small electromagnetic braking loss has been analyzed. Electromagnetic braking loss of the disk type engine becomes about 95% smaller than that of the cylinder type engine. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 154(4): 68–74, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20127

Fundamental Performance on Triple Magnetic Circuit Type Cylindrical Thermomagnetic Engine

The engine essentially consists of a rotor made of temperature sensitive magnetic material and permanent magnets. When an object made of this material has temperature distribution in the magnetic field, the force is generated to the direction from the low temperature side to the high temperature side by magnetic pressure. This paper describes the fundamental performance of the triple magnetic circuit type thermomagnetic engine. The triple magnetic circuit type engine with water-cooling system has been designed. The performance characteristics such as power, resistance loss, and the relation between the temperature of the rotor and the rotation speed has been measured, and compared with the characteristics of single magnetic circuit type engine. The net power is a maximum value of 3.7W at the rotation speed of 0.4rps. The power of the triple magnetic circuit type engine per unit magnetic circuit is about 4 times larger than that of the single magnetic circuit type engine. The resistance loss is of 1.7W at the maximum power point. The total power is of 5.4W. Electromagnetic braking loss is about 25% of the total power. The rate of electromagnetic braking loss to the total power increases with the rotation speed. The disc type rotor with small electromagnetic braking loss has been analyzed. Electromagnetic braking loss of the disc type engine becomes smaller about 95% than that of the cylinder type engine.

Permanent magnet pulse motor with high temperature superconducting levitation

A simple but stable noncontact high T/sub c/ superconducting levitation system with a vertical shaft has been presented. The levitation system consists of a superconductor and permanent magnets. In the system, a high T/sub c/ superconductor supports a lower end of the shaft, and a pair of permanent magnets supports the other end. Although a levitation is stable when the levitation system is used, since the restoring force is small in the horizontal direction, the levitation stability is small in the horizontal direction. Hence, it is difficult to drive the shaft by electromagnetic forces in using such motors. This paper describes a driving system consisting of six coils and a permanent magnet with eight poles, in which balance forces act on two opposite sides of the disc type rotor in the axial direction. The system has no unbalance force, and stable rotation is obtained without control. To validate the proposed system, experimental tests have been carried out. The experimental motor achieved stable rotation at speeds up to 1250 rpm.

Pulse motor with high-temperature superconducting levitation

A simple but stable noncontact high T/sub c/ superconducting levitation system with a vertical shaft has been presented. The system consists of a superconductor and permanent magnets. In the system, only a high T/sub c/ superconductor supports the lower end of the shaft, and the other end is supported by two ordinary permanent magnets. Since the restoring force is small with respect to the radial direction, the system becomes unstable when the force acts in the radial direction, so it is difficult to drive the shaft by electromagnetic forces when using motors. A driving system using electromagnets has been presented, in which the balanced forces act on two opposite sides of the disc-type rotor in the axial direction. Since the system has no unbalanced force from an analytical point of view, the rotor will be able to rotate without control. In the system, however, since there is eccentricity between the center of rotation and the magnetic center, vibrations are generated. This study also presents an optimal control method for the vibrations. To validate the proposed system and the control method experimental tests have been carried out.