Type Magnetic Gear Research Articles

A Novel Magnetic-Geared Motor Combining Magnetic Gear and SR Motor

A direct-drive permanent magnet (PM) motor and a magnetic-geared PM motor have the advantage of high torque density. Therefore, these motors are expected to be applied as in-wheel motors for electric vehicles (EVs). However, they have a problem that it is difficult to achieve the wide speed-torque characteristics required for EVs. This paper presents a novel magnetic-geared motor that consists of a flux-modulated type magnetic gear and a switched reluctance (SR) motor. In this paper, the SR motor part and the magnetic gear part are designed, and both parts are combined into a magnetic-geared motor. The proposed magnetic-geared motor has the wide speed-torque characteristic, which direct-drive PM motors or SR motors cannot achieve.

Self-powered flow sensing for automobile based on triboelectric nanogenerator with magnetic field modulation mechanism

Automobile flow sensors are critical in ensuring the engine air-fuel ratio, improving fuel efficiency, and reducing pollution. This paper presents a self-powered shaftless turbine intake flow sensor (STIFS) for automobiles consisting of a ball-bearing triboelectric nanogenerator (BB-TENG) and a magnetic field modulation type magnetic gear electromagnetic generator (MG-EMG). The contact electrification between the rolling ball and the outer ring of the BB-TENG generates a periodic electrical signal for flow sensing. In particular, the magnetic gear can improve the BB-TENG signal frequency and MG-EMG output performance. The smoothness of the airflow is improved by designing the shaftless turbine using the computational fluid dynamics (CFD) method, and the start flow of the STIFS is 160 L/min. The sensing sensitivity of the STIFS reaches 0.71 Hz/L·min−1·in the monitoring range of 300–900 L/min, and there is a well linear relationship between frequency and flow rate. In addition, the MG-EMG can generate output voltages and currents of 374 V and 31 mA to power data analysis and transmission modules in real-time. This work presents a novel methodology for self-powered wireless airflow sensing in large-flow pipelines, such as automobile intake pipes.

Analysis of Electromagnetic Performance of Modulated Coaxial Magnetic Gears Used in Semi-Direct Drive Wind Turbines

Wind turbine is a key device to realize the utilization of wind energy, and it has been highly valued by all countries. But the mechanical gear transmission of the existing wind power device has the disadvantages of high vibration and noise, high failure rate, and short service time. Magnetic field modulation electromagnetic gear transmission is a new non-contact transmission method. However, the conventional modulation magnetic gear has low torque density and torque defects with large fluctuations. In order to overcome the gear transmission problems of the existing semi-direct drive wind power generation machinery and improve the electromagnetic performance of the traditional magnetic gear transmission, this paper proposes a new transmission scheme of a non-contact semi-direct drive wind generator with a surface mount Halbach array modulated magnetic gear method, and considers the electromagnetic properties of the semi-direct drive modulation magnetic gear of the wind turbine. The finite element software is used to construct the model of the surface-mounted Halbach array magnetic gear and the conventional gear, analyzed the distribution of magnetic field lines of the two magnetic gears, calculated the air gap magnetic flux density of the inner and outer air gap, and obtained the main harmonics of the inner and outer air gap magnetic density; calculated the static torque and steady-state operating torque of the inner and outer rotors in the model, compared the air gap flux density, harmonics and torque of the magnetic gears. The simulation results show that the magnetic field modulation type magnetic gear of the surface mount Halbach array magnetic gear method improves the magnetic induction waveform of the inner and outer air gap, reduces the pulse torque fluctuation, and has a 60% higher static torque. Applying it to semi-direct drive wind power generation equipment not only overcomes the shortcomings of mechanical gears, but also has higher electromagnetic performance. Therefore, the surface-mounted Halbach array modulated magnetic gear can be used to replace the mechanical gearbox in the semi-direct drive wind power generation equipment.

Development of spoke-type IPM magnetic gear

Magnetic gears can change output-torque and -speed without any mechanical contacts. Therefore, they have a low acoustic noise and vibration, and their maintainability and reliability are high. Especially, a flux-modulated type magnetic gear is expected to be put into practical use because its torque density is higher than that of other magnetic gears. For the practical use, further improvement of torque and losses is important, especially, reduction of eddy current loss in permanent magnets (PMs) due to asynchronous harmonic magnetic fluxes is necessary. This paper investigates an interior permanent magnet (IPM) structure to improve the efficiency by reducing the eddy current loss in PMs. In addition, this paper presents a method for increasing torque of the IPM magnetic gear by changing a position of magnetic-bridge.

Comparison of Axial Magnetic Gears Based on Magnetic Composition Topology Differences

This paper proposes a design and implementation of an axial type magnetic gear (MG) based on the composition of the magnetic arrangement. We report a quantitative comparison of two MG topologies with rectangular magnets arranged in series and parallel. Increased magnetic flux is done through magnetic circuit analysis and electrical circuit approach. Testing is done by using the rotation of a DC motor drive from 300–2600 rpm with a DC generator under load conditions. Measurement of load current and generator output power for both axial MG topologies are taken and analyzed. The results showed that the performance of an axial MG with the rectangular magnetic arrangement in parallel is better than that of a series arrangement. Based on the measured loading current of the two axial MG topologies, at generator rotation between 300–1300 rpm with 100, 200, and 300 Ω resistance loads show the same load current. Conversely, after a DC generator rotation approaches ½ of the maximum rotation (1300–2600 rpm) there is a significant increase in load current fluctuations. That is, with an increase of load currents occurring, the parallel magnetic topology shows an increase in load torque due to an increase of magnetic flux in the gear train magnets of the MG.

A comparative analysis of power density for single-stage and dual-stage magnetic gear with rare-earth magnets and non rare-earth magnets

The magnetic gear that solves the physical contact problem of the mechanical gear has advantage of no mechanical frictionloss, very littlenoise and vibration, and no need for lubricant. Due to this unique non-contact characteristic, themagnetic gear which is capable of non-contact torque transmission has replaced mechanical gear. However, the magnetic gear with a high gear ratio is disadvantageous to implement the exact gear ratio because the number of rotor poles increases. Therefore, dual- stage type magnetic gear was proposed in order to distributes the gear ratio by using two magnetic gears as to the mechanical gear is used the multi-stage in order to implement the high gear ratio. The dual-stage type magnetic gear can improve the power density and efficiency compared to the single-stage magnetic gear. Also, the dual-stage type magnetic gear can be designed differently permanent magnet type because the use of the two magnetic gear. Therefore, in this paper, permanent magnet material of second magnetic gear was not changed and only permanent magnet material of first magnetic gear was changed to bonded NdFeB magnet or ferrite magnet from sintered NdFeB magnet. Transfer torque and magnetic field analysis method for dual-stage magnetic gear was used 2-D numerical analysis.

A Novel Flux-Modulated Type Dual-Axis Motor for Hybrid Electric Vehicles

This paper presents a novel flux-modulated type dual-axis motor that has two mechanical inputs/outputs, since it consists of a stator, a permanent magnet rotor, and a modulating rotor. Furthermore, since the dual-axis motor has a function the same as a planetary type magnetic gear, it can transmit torque with arbitrary gear ratio and divide mechanical input/output into two rotors without any mechanical contact. In this paper, first, conventional and proposed flux-modulated type dual-axis motors are optimized and compared using finite-element analysis. Next, the proposed dual-axis motor is prototyped and demonstrates the validity and availability by experiment.

Performance improvement of magnetic gear and efficiency comparison with conventional mechanical gear

Magnetic gears can transmit torque without any mechanical contact. Hence, they have low vibration, no wear, and fatigue, which ensure maintenance-free operation. There are various types of magnetic gears. Among them, a planetary type magnetic gear, which consists of coaxial inner and outer rotors with surface-mounted permanent magnet and ferromagnetic stationary parts called pole-pieces, has recently attracted interest since it offers higher torque than other type magnetic gears. This paper presents a comprehensive investigation of the influence of geometry and position of the pole-pieces on torque characteristic based on finite element analysis and experiment. Surveyed parameters of the pole-pieces include lengths in the radial and axial directions and position in the radial direction. Finally, it is demonstrated that the maximum torque of the improved prototype magnetic gear is increased by 45% and the maximum efficiency achieves up to about 99%, which is equal to or more than a conventional planetary type mechanical gear.

Development of surface permanent magnetic gear with stackable structure

A magnetic gear can transmit torque without contact by magnetic force. So it doesn't have wear, dust, vibration and noise. Therefore we don't have to use lubricant oil. In addition the magnetic gear has a torque limiter function. Many kinds of the magnetic gear are studied, but the magnetic gears have a demerit which the use efficiency of magnet is low. So surface permanent magnetic gears are studied because of their high magnet use efficiency and large transmission torque. However surface permanent magnetic gears are difficult to assemble. In this research, a prototype surface permanent magnetic gear which has the structure of only one layer with stackable structure is produced, measured the characteristic and examined, before producing the magnetic gear with multilayered structure. A new type magnetic gear is confirmed to be able to transmit the rotary motion through experiments.

Influence of Pole-Pieces on Characteristics in Planetary Type Magnetic Gear

Influence of Pole-Pieces on Characteristics in Planetary Type Magnetic Gear

Finite-Element Analysis of the Magnetic Field in a Magnetic Gear Mechanism

This paper presents finite-element analysis (FEA) of the magnetic field of a magnetic gear mechanism. An external type magnetic gear mechanism, which consists of two identical magnetic gears with sector-shaped permanent magnets, is introduced first. Then, the magnetostatic field distribution and transmitted torque of the magnetic gear mechanism are simulated by a commercial FEA package Ansoft/ Maxwell. Next, the effects of design parameters, including the air-gap length, the number of magnetic pole pairs, and the height of permanent magnets, on the maximum transmitted torque are discussed. The results of this work are beneficial to the design of magnetic gear mechanisms.

Evaluation of Experimental Result and Utility of Flux Modulated Type Magnetic Gear

A prototype of the flux-modulated type magnetic gear is manufactured and tested to evaluate its efficiency and torque transmission characteristics. According to the test results, the maximum torque transmission is proportional to the gear's size and the flux density of each rotor. The efficiency of the gear is dependent upon core material and core shape. As for the gear made for trial purposes, the efficiency of 99% was obtained in the maximum. The prototype gear obtained comparative advantages over mechanical gears with respect to efficiency and noise.

Study on Improvement of Transmission Torque for a Surface Permanent Magnet Type Magnetic Gear

Magnetic gears are a force transmitter consisting of permanent magnets. The mechanical input can be transmitted to an output shaft without contact by magnetic forces. The magnetic gears are not worn out because there is no friction. As a result, the running costs such as the maintenance fee can be suppressed and the resources can be saved. However, the transmission torques of the conventional magnetic gears, which have so far been developed, are very low. Besides, new structure models designed for high torque density need a lot of permanent magnets and multi-pole constructions. Those structures are complex and the manufacturing is difficult. In this research, we applied a flux concentration type surface permanent magnet arrangement to a surface permanent magnet type magnetic gear in order to improve the transmission torque and to reduce the amount of permanent magnets. The magnetic flux distribution, the gap flux density and the transmission torque of the developed new models are numerically analyzed by using the two-dimensional finite element method. In this paper, a permanent magnet structure optimized to reduce its amount and influence of the flux concentration type surface permanent magnet arrangement on the gap flux density distribution and transmission torque are reported.