A NEW DC MACHINE ARRANGEMENT FOR AN ELECTRONICALLY ASSISTED COMMUTATION

The d.c. machine is the cheapest way to realize variable speed drives. However its performances axe limited by the commutator operation. Ind eed, the latter wears out very rapidly because of the sparks, even arc ings, which appear between the segments and the brushes, in spite of u se of commutating poles. Over the last fifteen years, our laboratory h as implemented external circuits to assist commutation and alleviate, or even suppress, the main difficulties. This paper presents a new arr angement which seems very promising.