A novel high-performance magnetic gear
TL;DR: In this article, the design and performance of a magnetic gear, which employs rare-earth magnets, has been described, which simulation studies have shown to have a transmitted torque density exceeding 100 kNm/m/sup 3.
Abstract: Mechanical gearboxes are used extensively to match the operating speed of prime-movers to the requirements of their loads. Although, high system torque densities can be achieved, gear lubrication and cooling are often required, whilst noise, vibration and reliability can be significant issues. The paper describes the design and performance of a magnetic gear, which employs rare-earth magnets, which simulation studies have shown to have a transmitted torque density exceeding 100 kNm/m/sup 3/.
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TL;DR: An overview of permanent-magnet (PM) brushless (BL) drives for EVs and HEVs is presented, with emphasis on machine topologies, drive operations, and control strategies.
Abstract: With ever-increasing concerns on our environment, there is a fast growing interest in electric vehicles (EVs) and hybrid EVs (HEVs) from automakers, governments, and customers. As electric drives are the core of both EVs and HEVs, it is a pressing need for researchers to develop advanced electric-drive systems. In this paper, an overview of permanent-magnet (PM) brushless (BL) drives for EVs and HEVs is presented, with emphasis on machine topologies, drive operations, and control strategies. Then, three major research directions of the PM BL drive systems are elaborated, namely, the magnetic-geared outer-rotor PM BL drive system, the PM BL integrated starter-generator system, and the PM BL electric variable-transmission system.
1,281 citations
Cites background from "A novel high-performance magnetic g..."
...Magnetic gearing is becoming attractive since it offers the advantages of high efficiency, reduced acoustic noise, and maintenance free [44]....
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01 Mar 2004
TL;DR: In this paper, a new magnetic gear topology which combines a highly competitive torque transmission capability and a very high efficiency is described, which is based on the magnetic circuit topology.
Abstract: Magnetic gears offer significant potential advantages compared with mechanical gears, such as reduced maintenance and improved reliability, inherent overload protection, and physical isolation between the input and output shafts. However, to date they have received relatively little attention, probably due to the relatively poor torque transmission capability of the magnetic circuit topologies which have been proposed. A new magnetic gear topology which combines a highly competitive torque transmission capability and a very high efficiency is described.
582 citations
12 Oct 2003
TL;DR: In this paper, the authors presented a high-performance permanent-magnetic gear with a gear ratio of 5.5 and a torque of 27 N/spl middot/m.
Abstract: This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses of magnetic origin in the bearings and less end-effects caused by relatively short stack, an impressive efficiency estimated at 96% can be obtained. Comparison with classical mechanical gears has shown that the magnetic gear has a better efficiency and a comparable torque per volume density. Finally, it is concluded that the results in this paper may help to initiate a shift from mechanical gears to magnetic gears.
429 citations
Cites background from "A novel high-performance magnetic g..."
...0093-9994/$20.00 © 2005 IEEE The papers referred to above all deal with magnetic gears having a poor utilization of the permanent magnets and, thus, very low torque per volume density....
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...After this, a comparison to classical commercial gearboxes is made in Section V and, finally, a conclusion is given in Section VI....
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TL;DR: A novel in-wheel motor is proposed, which artfully integrates a magnetic gear into a permanent-magnet brushless (PMBL) DC motor so that they can share a common PM rotor, hence offering both high efficiency and high power density.
Abstract: This paper proposes a novel in-wheel motor, which artfully integrates a magnetic gear into a permanent-magnet brushless (PMBL) DC motor so that they can share a common PM rotor, hence offering both high efficiency and high power density. Moreover, the low-speed requirement for direct driving and the high-speed requirement for compact motor design can be achieved simultaneously. A 2-kW 600/4400-rpm magnetic-geared outer-rotor PMBL DC motor is designed and analyzed, which is particularly suitable for battery-powered electric motorcycles
348 citations
Cites background from "A novel high-performance magnetic g..."
...This magnetic gear was first proposed in [3]....
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...Magnetic gearing is becoming attractive, since it offers the advantages of high efficiency, reduced acoustic noise, and maintenance free [3]....
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15 Oct 2007
TL;DR: In this paper, a new permanent magnet brushless generator for wind power generation is presented, which adopts an outer-rotor topology, aiming at capturing wind power directly.
Abstract: This paper presents a new permanent-magnet (PM) brushless machine for wind power generation. This machine adopts an outer-rotor topology, aiming at capturing wind power directly. In order to achieve high power density, a high-speed PM brushless generator is artfully integrated with a coaxial magnetic gear. The design details, with emphasis on the special constraints of wind power generation, are elaborated. By using the time-stepping finite element method, the static characteristics as well as no-load and on-load operations are simulated. A prototype is also built for experimentation. Both simulation and experimental results are given to verify the validity of the proposed machine. Finally, a quantitative comparison is made to justify that the proposed machine is of smaller size, lighter weight, and lower cost than its counterparts.
327 citations
References
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TL;DR: In this article, the authors describe the structure and the performance characteristics of a magnetic gear using SmCo 5 for the permanent magnet, which has a gear ratio of 1/3 and the maximum transmitted torque is 5.5 Nm at the driven magnetic gear.
Abstract: This paper describes the structure and the performance characteristics of a magnetic gear using SmCo 5 for the permanent magnet. The magnetic gear has a gear ratio of 1/3 and the maximum transmitted torque is 5.5 Nm at the driven magnetic gear. When the rotating speed of the driving magnetic pinion is 2000 rpm, the driven magnetic gear rotates at 2000/3 rpm in the no load condition. The results of this study seem to be useful for the development of industrial application of noncontact magnetic gears.
114 citations
01 Nov 1996
TL;DR: In this paper, the surface-magnet form of an electric motor with rotor magnets interacting with homopolar stator windings has been investigated and the optimum values for the following ratios were determined: C-core pitch/gap, magnet depth/gap and c-core width/C core pitch.
Abstract: Electric motors that embody heteropolar arrays of rotor magnets interacting with homopolar stator windings are capable of exceptionally high levels of torque per unit volume or mass. Design studies of the surface-magnet form of this class of machine have determined optimum values for the following ratios: C-core pitch/gap, magnet depth/gap, and C-core width/C-core pitch. The results are presented partly in the paper, which concentrates on three-dimensional computational design studies and on physical discussion of behaviour, and partly in a companion paper, which concentrates on theory of performance and figures of merit for design.
63 citations
"A novel high-performance magnetic g..." refers background in this paper
...Of the various competing direct drive machine topologies, permanent magnet transverse-field machines offer potentially the highest torque densities [3], [4], typically in the range 40–80 kNm/m ....
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01 May 1980
TL;DR: In this paper, an appraisal of the problems inherent in the production of a magnetic gear is presented, together with the theoretical basis of its operation, and is compared with a simple wheel gear.
Abstract: The paper presents an appraisal of the problems inherent in the production of a magnetic gear. A new form of gear is presented, together with the theoretical basis of its operation, and is compared with a simple wheel gear. Experimental results are included for a complete gear and for the constructional elements.
42 citations
"A novel high-performance magnetic g..." refers background in this paper
...In contrast, magnetic gearing has received relatively little attention, probably because of the relative complexity and poor torque density of the magnetic circuits which have been proposed [1], [2]....
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