Abstract: A brushless electric motor is disclosed. In an exemplary embodiment of the invention, the motor includes a permanent magnet rotor having a plurality of magnetic poles thereupon and a stator. The stator further includes a plurality of stacked laminations defining a plurality of slots therein, and a plurality of fractional-pitch phase windings disposed within the plurality of slots. The motor has a non-integer slots-per-pole ratio, and a magnitude of 5th and 7th harmonic components of a fundamental frequency component of the motor are less than 0.3% and 0.1% of a magnitude of the fundamental frequency component, respectively.

Abstract: A permanent magnet structure for use in brushless motors is disclosed. In an exemplary embodiment of the invention, the magnet structure includes a parallelogram shaped body. The body has an outer surface and an inner surface, with the outer surface and the inner surface being arcuate in shape.

Abstract: A brushless electric motor is disclosed. In an exemplary embodiment of the invention, the motor includes a permanent magnet rotor having a plurality of magnetic poles thereupon and a stator. The stator further includes a plurality of stacked laminations defining a plurality of slots therein, and a plurality of fractional-pitch phase windings disposed within the plurality of slots. The motor has a non-integer slots-per-pole ratio, and a magnitude of 5th and 7th harmonic components of a fundamental frequency component of the motor are less than 0.3% and 0.1% of a magnitude of the fundamental frequency component, respectively.

Abstract: A permanent magnet structure for use in brushless motors is disclosed. In an exemplary embodiment of the invention, the magnet structure includes a parallelogram shaped body. The body has an outer surface and an inner surface, with the outer surface and the inner surface being arcuate in shape.

Abstract: A brushless D.C. motor having a tolerance band that is used to retain the stator in the motor housing. The tolerance band has a plurality of waves formed along its length. The tolerance band is mounted within a housing groove, through which the stator is pressed. The tolerance band waves are compressed as the stator is pressed into motor housing. The compressed waves act as a radial spring to retain the stator in the housing with a minimal amount of radial force.

Abstract: A rotor assembly for a brushless motor is disclosed. In an exemplary embodiment of the invention, the rotor assembly includes a core having a central opening for insertion of a rotor shaft therein. A plurality of rotor magnets disposed upon a periphery of the core, wherein a space is defined between one of the plurality of rotor magnets and another of the plurality of rotor magnets. A portion of said core occupies said space, thereby defining a salient pole therewithin.

Abstract: A system for reducing torque ripple in an electric motor, comprising an electric motor having a stator and a rotor, a first set of N Hall sensors, a second set of N Hall sensors, a controller, and wherein said N Hall sensors in each said set of Hall sensors is spaced 360/N electrical degrees apart and said first and second sets of Hall sensors are spaced T electrical degrees apart, and wherein said controller is adapted to provide increased current during an overlap period detected by said Hall sensors.

Abstract: A method for determining a dimension in a motor is described. By applying Fourier analysis, a sequence of terms is obtained. Since the fifth harmonic is the most undesirable term, the minimization of the fifth harmonic term will make resultant waveform closer to sine wave. Based upon the above, a determination of an angle &dgr; is described, wherein the fifth harmonic term of the sequence of terms is minimized. An electric motor having a rotor and a set of slot on said rotor surface having a set of magnets with a width &dgr; along the circumference of said rotor surface is described. The width &dgr; is determined by a method that includes applying Fourier analysis thereby a sequence of terms is obtained. Since the fifth harmonic is the most undesirable term, the minimization of the fifth harmonic term will make resultant waveform closer to sine wave. Based upon the above, a determination of an angle &dgr; is described, wherein the fifth harmonic term of the sequence of terms is minimized.