Analysis, Design of High Performance Magnetics
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.
Value of a Magnetic Clutch in an EV vehicle
This paper examines the benefits of a drivetrain that is able to disengage its propulsion motor from the driveline in an electric vehicle. The drivetrain was developed for an ultra-efficient eco vehicle competing in the Shell 2013 Eco Marathon. Various clutch mechanisms were examined. In spite of the complexity and losses associated with additional bearings and release surfaces, an actuated dog clutch was chosen as it offers superior performance due to the dual capability of freewheeling and regenerative braking that results. Track data from the event is presented along with experimental work that indicates that the clutch mechanism reduces power consumption by more than 35% for a ferrous permanent magnet propulsion motor. Savings were reduced to 5% for a coreless permanent magnet motor coupled to the driveline via an 11:1 straight cut spur gear arrangement. This reduced saving was due to the removal of hysteresis and eddy current losses from the stator. The paper also demonstrates during a competition in which the driver was aware of the energy consumption, the driving style changed when the technological option to free wheel was available. Finally the study was inferred onto a real world application with further experimental and simulation work on the Delta E4 Coupe, a high performance electric sports car. The vehicle uses a ferrous permanent magnet direct drive arrangement, indicated a reduction in power consumption of 10 to 14%. It is hoped that these insights are relevant when considering the development of electric vehicle drivetrains where machine topology and drive cycle will determine the value of a clutch mechanism.
A Review on Magnetic Gears: Topologies, Computational Models and Design Aspects
Geared devices are commonly used to match the operating speed and torque of the power source with the second-mover. Such geared devices are usually mechanical gears. As counterparts of the conventional mechanical gears, magnetic gears are becoming promising devices, mainly due to the merits of physical isolation between moving parts, no gear lubrication, no mechanical fatigue, inherent overload protection and reduced maintenance, etc. Recently, several new topologies have been proposed to achieve better performances. In this paper, a general review of magnetic gears is presented, including a discussion of the most common and upcoming topologies and a description of the working principle. A comparison of different topologies is carried out, in terms of gear ratio and torque density. The main computational techniques generally adopted for coaxial magnetic gears are listed and described. Some key aspects concerning the design, the existed challenges and potential applications are also discussed. This paper aims to provide a comprehensive overview of the magnetic gear for readers working in this field.
Magnetic Gears
In mechanical gear systems, dust, noise, vibration, and tooth wear are generated by frictions among gear teeth, and suppressing friction requires lubrication. Magnetic gears transmit torque by magnetic forces without contact and so avoid contact-related problems. The present paper discusses magnet arrangements and the shape of stationary gear teeth to improve transmission torque in surface magnet type magnetic gear transmission mechanisms.