Electric vehicle traction motors without rare earth magnets. Abstract. Since the Hybrid Electric Vehicle (HEV) became main- stream with the launch of the Toyota Prius in 1. In particular the rare earth based, hard magnetic material Neodymium Iron Boron (Nd. Fe. B) has offered significant performance benefits, not possible with other technologies, enabling the development of compact, torque- and power- dense electric traction motors. This trend has continued as mass market Battery Electric Vehicles (BEV) such as the Nissan Leaf, have come to market. However in 2. 01.
Tesla Motors, Inc. is an American automotive and energy storage company [5] that designs, manufactures, and sells luxury [6] electric cars, electric vehicle powertrain components, and battery products. [7] Tesla Motors is a. 2. ELECTRIC MOTORS Syllabus Electric motors: Types, Losses in induction motors, Motor efficiency, Factors affecting motor performance, Rewinding and motor replacement issues, Energy saving opportunities with energy efficient.
Whilst the price has recovered more recently closer to historical levels, concern still remains in the minds of governments and many manufacturers of hybrid and electric vehicles. Reports have also raised questions over the environmental sustainability of these materials and this has further encouraged users to consider alternatives.
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- Electric Motors and Drives Fundamentals, Types and Applications Third edition Austin Hughes Senior Fellow, School of Electronic and Electrical Engineering, University of Leeds AMSTERDAM • BOSTON • HEIDELBERG • LONDON.
This paper therefore examines why these magnetic materials have been so successful in traction motor applications. It also explores the alternatives, including those which are ready for market and those which are in the process of being developed. Keywords. Electrical machines; Rare earth magnets; Electric vehicles; Traction motors. Introduction. 1. 1.
Neodymium Iron Boron magnets and electric traction motors. The sintered Neodymium Iron Boron (Nd. Fe. B) hard magnetic material was patented by Sumitomo Special Metals in 1. Fig. 1) and brought about a step change in terms of electric motor performance. Neodymium is a member of the family of materials known as Light Rare Earth Elements (LREE), along with others including for example Lanthanum (used in optics) and Samarium (also used in magnetic materials). Fig. 1. (Left) An example of a sintered Nd. Fe. B magnet and (right) a vehicle traction motor, the 8.
Unlike other electric motor types (i.e., brushless DC, AC induction), BDC motors do not require a controller to switch current in the motor windings. Instead, the commutation of the windings of a BDC motor is done mechanically. How real electric motors work John Storey Note: These pages are intended to be read in conjunction with Joe's 'Electric motors and generators' pages (http:// Read. Largest Selection of Electric Motors & Controllers in the World, for the Golf Cart Aftermarket. Heavy Duty - High Speed & High Torque Motors for Electric Golf Carts. Need more performance? Look to D&D Motor Systems, Inc. Since the Hybrid Electric Vehicle (HEV) became main-stream with the launch of the Toyota Prius in 1997, the use of rare earth magnets in vehicle traction motors. A brushed DC motor is an internally commutated electric motor designed to be run from a direct current power source. Brushed motors were the first commercially important application of electric power to driving mechanical.
W interior permanent magnet motor from the Nissan Leaf, in which such magnets are used. These magnets offer such high levels of performance owing to their very high Maximum Energy Product compared to other magnetic materials (Fig. 2). The Maximum Energy Product is the measure of the magnetic energy which can be stored, per unit volume, by a magnetic material; it is calculated as the maximum product of a material's residual magnetic flux density (degree of magnetisation) and its coercivity (the ability to resist demagnetisation once magnetised).
Equally, if each of these constituent properties, the remnant flux density and coercivity, is taken separately then in Nd. Fe. B they are in their own right significantly higher than for other magnetic materials (Fig. 3) [2], [3] and [4]. Fig. 2. Comparison between the Maximum Energy Product of differing hard magnetic materials. Fig. 3. Comparing remnant flux density (magnetic strength) and coercivity (resistance to demagnetisation) for different hard magnetic materials. It is also important to recognise that a key ingredient in allowing Nd. Fe. B magnets to operate at high ambient temperatures is Dysprosium; this Heavy Rare Earth Element (HRE) is added to Nd.
Fe. B in order to increase the high temperature coercivity (ability to withstand demagnetisation) of the magnets above circa 1. C [5]. This has been essential in making it possible to use these magnets in high power density applications, such as vehicle traction. In an electric traction motor, Nd. Fe. B magnets allow a very strong magnetic field to be generated in a very small volume. The alternative would be to use electromagnets, where a magnetic field is generated by passing current through a conducting coil. It can be shown that a 3 mm thick piece of Nd.
Fe. B magnet produces the equivalent magnetic field to passing 1. A (being the rating of a UK home electrical socket) through a coil with 2. In terms of space, if a current density of 1. A/mm. 2 is assumed in the conductor (which is typical for normal operation of a traction motor), then an equivalent electromagnetic coil might have five times the cross sectional area of the Nd. Fe. B magnet (Fig. 4).
At the same time the coil would produce losses in the windings of 5. W or more per metre length of the coil, arising due to the electrical resistance of the conductor. To put this in perspective, in a representative 8. W traction motor the optimum use of Nd. Fe. B magnets would theoretically be equivalent to saving perhaps 2. W of winding loss.