Technical Paper
A Cost Effective Brushless D.C. Motor
1986-02-01
860475
The design and performance of a brushless d.c. motor with high power density using ferrite magnets and a two transistor drive is described. The motor utilizes a single-phase operating principle which permits the use of an electronic drive circuit utilizing only two power switching devices, making it cost effective with a conventional d.c. commutator motor using P.W.M. speed control. High power density is obtained by the use of an external rotor construction and a multi-pole format with a concentrated winding. The starting problems normally associated with single-phase motors is addressed and an experimentally proven solution is described. Significant reduction in starting current is achieved as a no cost bonus and significant improvements in overall operating efficiency can be obtained if the power density is reduced to normal auto industry levels.