Brushless D.C. dynamoelectric machine with decreased magnitude of pulsations of air gap flux
AssigneeMaghemite Inc.
InventorEric Whiteley
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Abstract
A dynamoelectric machine which may operate in a motor mode or a generator mode is described wherein substantially the entire magnetic circuit is provided by ferrite material. In one particular embodiment, hard ferrite permanent magnet segments are mounted on a rotor plate while soft ferrite magnet segments with electrical coil windings mounted thereon are provided in a stator spaced apart from the rotor by an air gap. Other embodiments of the concept are described. Provision is made for decreasing mechanical vibration and audible noise by decreasing the magnitude of pulsations of air gap flux.
Claims12
In a brushless D.C. dynamoelectric machine, which comprises:
- a disc-like rotor element comprising hard ferrite toroid means providing a plurality of magnetic poles of alternating polarity and mounted for rotation about its axis,
- a disc-like stator element comprising soft ferrite toroid means and mounted coaxially with and spaced apart from the rotor element to define an air gap therebetween, said soft ferrite toroid means being formed with radially-directed coil winding-receiving slots, and
- electrical coil windings mounted to said stator in said slots, the improvement which comprises means for decreasing the magnitude of pulsations of air gap flux during rotation of said rotor with respect to said stator.
In a brushless D.C. motor wherein the magnetic structure consists of a toroid-shaped set of hard ferrite permanent magnet poles mounted on a rotor disc and a soft ferrite toroid mounted in a stator frame with an axial air gap between the two toroid components, the improvement wherein stator windings are provided in slots at the air gap face of the stator toroid, said windings being arranged in the fewest practical number of slots, equal to twice the number of rotor poles, and arranged in multiple circuits to produce essentially continuous motor torque when energized in sequence and in synchronism with rotor pole positions by unidirectional pulses of D.C. current.
Dependencies are inferred from the claim text.