Axial field electric machine

Abstract

An axial field electric machine having an improved efficiency includes a number of magnetic elements (e.g., as a rotor) as annular disks magnetized to provide multiple sector-shaped poles. Each sector has a polarity opposite that of an adjacent sector, and each sector is polarized through the thickness of the disk. The poles of each disk are aligned with opposite poles of each adjacent magnet. Metal members adjacent the outermost disks contain the flux. The axial field electric machine also includes one or more conductor elements (e.g., as a stator) which include a number of conductor phases that traverse the flux emanating between poles of axially adjacent magnetic elements. The design of the axial field electric machine including the gap spacing between adjacent magnetic elements, the transition width between adjacent poles on each magnetic element, the number of poles, the number and width or conductor phases in the conductor element is based on the physical characteristics of the magnetic elements to increase efficiency.

Description

[0001] The present application is a continuation-in-part of U.S. application Ser. No. 08 / 763,824, the disclosure of which is hereby incorporated by reference in its entirety.[0002] 1. Field of the Invention[0003] The present invention relates generally to electric machines or motor / generators and, more specifically, to permanent magnet, axial field electric machines.[0004] 2. Description of the Related Art[0005] An electric motor / generator, referred to in the art as an electric machine, is a device that converts electrical energy to mechanical energy and / or mechanical energy to electrical energy. Since electric machines appear more commonly as motors, the ensuing discussion often assumes that electric energy is being converted to mechanical energy. However, those knowledgeable in the art recognize that the description below applies equally well to both motors and generators.[0006] Electric machines generally operate based on Faraday's law, which can be written as e=BLv, and the Lore...

AI Technical Summary

Problems solved by technology

As a result, this motor does not utilize materials, design steps, or construction techniques that lead to high efficiency over a broad range of speeds, high motor constant, or high power density.

The floppy disk spindle motor uses an axial field topology solely because there is insufficient axial space available inside the floppy disk housing to use a radial field motor.

In servomotor applications where a motor does not turn continuously but rather starts and stops frequently, efficiency is not a good measure of motor performance because efficiency is zero at zero speed, i.e., .omega.=0.

In any case, since output power is the product of torque and speed, power density increases linearly with speed to the point where it is no longer possible to maintain torque production, at which point power density decreases.

2, the ability to produce torque is only limited by the ability to remove the heat created by the resulting I.sup.2R loss P.sub.r and the speed dependent losses P.sub.c and P.sub.m, which decrease efficiency.

As a result, additional cost is incurred in traditional motors due to the additional capital expense and inventory required to support a family of motors at a given diameter.

Conductive material that does not traverse this magnetic flux contributes to the mass and losses of the machine and thereby reduces the efficiency and power density of the machine.

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