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RESEARCH PRODUCT

Different Permanent-Magnet Structures and their Influence on the Torque of Small DC Motors

subject

description

The design of permanent-magnet DC micromotors implies solving a number of problems. A few of them belong to all DC micromotors, i.e. size and number of rotor slots, width of air gap, external stator and internal rotor diameter, ratio of length to rotor diameter etc.1. One problem, certainly not the lowest in importance is, however, specific2, i.e. the choice of the most convenient permanent magnet for prescribed specifications of the micromotor. To date the progress in the production of permanent magnets has made it possible to work out different structures of motors and, for each structure, the most suitable permanent magnet for specified applications. Rare-earth permanent magnets and, in particular, those based on Samarium-Cobalt are so far rather expensive; this suggests their use in small volumes and especially in those cases where high values of torque are required.