JPS5635671A - Brushless motor - Google Patents

Abstract

PURPOSE:To produce torque in a fixed direction at all arbitrary positions of a rotor by a method wherein there are used a field magnet of the rotor having magnetic pole width in equalized pitch and a prescribed distribution of the magnetic flux density. CONSTITUTION:The magnetic poles of the field magnet 5 of the rotor are magnetized in an equalized pitch, for example, the poles N and S are magnetized in the equalized pole pitch with the point of theta=180 deg. as a center, and for example, the width in the axial direction of the field magnet 5 is made larger (l) on one side and narrower (u) on the other side with the central position of the magnetic poles put between, in order that the positions where the maximum density of magnetic flux of individual magnetic poles N and S respectively are deviated near a magnetically neutral point (0 deg. or 360 deg.) rather than the central positions (90 deg. or 270 deg.) of the individual poles N and S. And now, the stator windings 1, 2 provided with a plurality of fractional pitch windings by 180 deg. of the electrical angle are arranged to flow one-way currents through the stator windings 1, 2 with two switching elements.