Abstract: This paper describes the performance of d.c. servomotor and drive motor with Nd-Fe-B pennanent magnet based on theoretical analyses and experimental studies.Through the study of the developed samples and a comparison of similar machines,the conclusion reached is as follows:Nd-Fe-B PM d.c. micromachines have resulted in improved efficiency,reduced weight and increased mass/ power ratio. The high temperature coefficient and low temperature limit of Nd-Fe-B are very unfavourable factors. Because the temperature rise of developed sam-ples is lower,it will have not much influence on the perfonnance of d.c. micromotors. In that way,the eleetromachines of better performance can be manufactured so long as proper measures are taken in design. There are bright prospects for application of Nd-Fe-BPM in aviation.

Key words: iron alloys, permanent magnets, micromotors