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DESIGN AND ANALYSIS OF HIGH-SPEED BRUSHLESS PERMANENT MAGNET MOTORS.pdf

发布:2017-04-10约1.74万字共5页下载文档
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DESIGN AND ANALYSIS OF HIGH-SPEED BRUSHLESS PERMANENT MAGNET MOTORS Z.Q. Zhu, K. Ng, and D. Howe University of Shefield, UK INTRODUCTION High-speed brushless permanent magnet machines are likely to be a key technology for electric drives and motion control systems for many applications, since they are conducive to high efficiency and a high power density, small size and low weight [I] . However, due to the high fundamental operating frequency a more detailed consideration of various operational issues, such as stator iron losses and rotor parasitic eddy current losses, and the influence of the winding inductances on the dynamic system performance, is advisable at the design stage [2-51. The paper reports on the design of a 20,00Orpm, 3- phase brushless permanent magnet dc motor for use in a friction welding unit, in which studs up to 3mm diameter and welded by coordinating the rotational speed of the motor with the force applied by a linear permanent magnet servo-actuator. The motor consists of a stator having 3 teeth, which carry non-overlapping windings, and a 2-pole diametrically magnetised sintered NdFeB magnet rotor, as shown in Fig.]. The airgap flux density distribution is essentially sinusoidal. The advantages and disadvantages of such a motor topology for this and other high speed applications are discussed, and an optimal airgap diameter is derived. The effect of the stator tooth tip geometry on the waveform of the induced emf is investigated by finite element analysis, and validated by measurements, whilst the merits of laminated silicon iron and soft magnetic composite materials for the stator core are considered. GENERAL DESIGN CONSIDERATIONS The higher the operating speed of a motor the smaller is its physical size for a given output power. Hence, in the case of a permanent magnet machine, the lower will be the volume of magnet material. Therefore, high speed is particularly appropriate when rare-earth permanent
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