WO2011049555A1

WO2011049555A1 - Compact permanent magnet generator

Info

Publication number: WO2011049555A1
Application number: PCT/US2009/061278
Authority: WO
Inventors: Alan Martin
Original assignee: Arb Greenpower, Llc
Priority date: 2009-10-20
Filing date: 2009-10-20
Publication date: 2011-04-28

Abstract

Compact generator including a stationary stator assembly and a rotor assembly. The stator assembly includes a stationary ferromagnetic core having inwardly projecting stator poles uniformly spaced about an interior circumference of the stator assembly. First, second and third stator windings are successively wound around the stator poles. A non-ferromagnetic drum is axially coupled to the shaft. A longitudinal dimension of the non-ferromagnetic drum is disposed in rotational proximity to the stator assembly. A plurality of permanent magnets are slidably mounted to an outer circumferential surface of the non-ferromagnetic drum in alternating polarity.

Description

TITLE: COMPACT PERMANENT MAGNET GENERATOR

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is an international application related to applicant's expired U.S. provisional application serial no.: 61/100,521, filed 09/26/2008 and serial no.: 60/913,245, filed 04/20/2007. This non-provisional international application is also related to applicant's co-pending international application PCT/US09/31921, filed 01/24/2009. The aforementioned provisional applications and co-pending international application are hereby incorporated by reference in their entirety as if fully set forth herein.

RELEVENT FIELD

[0002] This application is directed generally toward electrical generators and more specifically toward permanent magnet type electrical generators.

BACKGROUND

[0003] Various generators known in the relevant art employ wire wound stator and rotor assemblies in which an electromagnetic force is produced in and around rotor windings by inducing current flow through the rotor windings. In such designs, as the magnetic field produced in the spinning rotor couples with the windings of the stator, current is induced in the stator windings. Exciter windings require brushes or slip rings to maintain current flow to these windings during rotation. Brushes or slip rings are mechanical connections which are susceptible to wear, corrosion and mechanical malfunction.

[0004] Permanent magnet generators do not require that external excitation energy be supplied which eliminates the need for the slip rings, brushes and other components which reduce the reliability of a generator, increase the overall weight and/or volume occupied by the generator. The magnetic field produced by permanent magnets attached to a rotor induces current flow in the stator windings as the rotor with the permanent magnets move in relation to the stator windings.

[0005] However, permanent magnet generators suffer from excessive heat generation which may lead to stator winding failure, permanent magnet disintegration and/or loss of magnetic properties of the permanent magnets. To remedy excessive heat generation, cooling fans, radiator fins and other heat removal components are added to the generator. These added heat removal components increase both the weight and bulk of the generator which make them undesirable in applications requiring compact size and/or light weight, for example, motor vehicle or aviation applications where fuel efficiency is directly dependent on weight. Alternately, or in combination with the added heat removal components, permanent magnet generators may be derated to prevent excessive internal heat buildup, thus requiring a larger generator than otherwise would be required if internal heat buildup were not a consideration.

[0006] Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

SUMMARY

[0007] In view of the foregoing, various exemplary embodiments of a compact permanent magnet generator are disclosed herein. In an exemplary embodiment, the compact permanent magnet generator comprises a stator assembly and a rotor assembly. The stator assembly includes a stationary ferromagnetic core having inwardly projecting stator poles uniformly spaced about an interior circumference of the stator assembly. First, second and third stator windings are periodically wound around succeeding stator poles. The rotor assembly includes a shaft mounted in axial rotational alignment within the stator assembly. A non-ferromagnetic drum is axially coupled to the shaft. A plurality of uniformly spaced permanent magnets are maintained within longitudinally aligned slots provided proximate with an outer circumferential surface of the non-ferromagnetic drum.

[0008] In an exemplary embodiment, each of the permanent magnets provides a surface magnetic flux density greater than 5000 Gauss.

[0009] In an exemplary embodiment, the non-ferromagnetic drum is constructed from an aluminum alloy.

[00010] In an exemplary embodiment, each of the permanent magnets is formed in an elongated shape.

[00011] In an exemplary embodiment, the slots are dimensioned to slidably receive the elongated shaped permanent magnets.

[00012] In an exemplary embodiment, the compact permanent magnet generator further comprises non-ferromagnetic stator housing covers coupled to opposing axial surfaces of the stator assembly. [00013] In an exemplary embodiment, the non-ferromagnetic drum further includes contralateral lips extending over minority portions of each of the slots.

[00014] In an exemplary embodiment, a longitudinal dimension of the non- ferromagnetic drum is less than a diameter of the non-ferromagnetic drum.

[00015] In an exemplary embodiment, the contralateral lips form a fixture for axially maintaining the plurality of permanent magnets within the non-ferromagnetic drum.

[00016] In various exemplary embodiments, one or more collection coils may be affixed to an external surface of a non-ferromagnetic stator housing cover. The collection coil being mounted tangential to an the outer circumferential surface of the non-ferromagnetic drum. The collection coil(s) may be configured to capture non- axial magnetic flux and convert the captured non-axial magnetic flux into an electrical current. A rectifier circuit may be coupled with the collection coil and an electrical energy storage device. The electrical current generated by the collection coil may be rectified by the rectifier circuit and stored in the electrical energy storage device.

[00017] In various exemplary embodiments, the number of permanent magnet may be 14; the number of stator windings per poll may be three and one-half turns; and the number of stator poles may be 42. The permanent magnet may be in juxtaposition with 2 through 3 stator poles. A stator cooling assembly may be provided in thermal communication with the stator assembly 20. The stator cooling assembly comprises non-ferromagnetic metal conduit which may be integrated into the stator assembly or axially wound around an exterior surface of the stator assembly.

BRIEF DESCRIPTION OF DRAWINGS

[00018] The features and advantages of the various exemplary embodiments will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. Where possible, the same reference numerals and characters are used to denote like features, elements, components or portions of the inventive embodiments. It is intended that changes and modifications may be made to the described exemplary embodiments without departing from the true scope and spirit of the inventive embodiments as is defined by the claims.

FIG.l - depicts an exploded isometric view of a compact permanent magnet generator in accordance with an exemplary embodiment. FIG.2 - depicts a cross-sectional view of a stator assembly in accordance with an exemplary embodiment.

FIG.2A - depicts a side view of a stator core in accordance with an exemplary embodiment.

FIG.2B - depicts a front view of a stator ferromagnetic disk in accordance with an exemplary embodiment.

FIG.3 - depicts a side view of a rotor assembly in accordance with an exemplary embodiment.

FIG.3A - depicts an axial view a rotor assembly in accordance with an exemplary embodiment.

FIG.4 - depicts a partial isometric view of the rotor assembly in accordance with an exemplary embodiment.

FIG.4A - depicts a close-up partial top view of a permanent magnet aligned with a plurality of stator poles in accordance with an exemplary embodiment.

FIG.4B - depicts a stator winding diagram in accordance with an exemplary embodiment.

FIG.5 - depicts a side view of a compact permanent magnet generator in accordance with an exemplary embodiment.

FIG.5A - depicts a rear end view of a compact permanent magnet generator in accordance with an exemplary embodiment.

FIG.5B - depicts a front end view of a compact permanent magnet generator in accordance with an exemplary embodiment.

FIG.6 - depicts a collection coil arrangement in accordance with an exemplary embodiment.

FIG.7A - depicts an external stator cooling arrangement in accordance with an exemplary embodiment.

FIG.7B - depicts an internal stator cooling arrangement in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

[00019] A compact permanent magnet generator is described herein. In the following exemplary description, numerous specific details are set forth in order to provide a thorough understanding of the present inventive embodiments. It will be apparent, however, to one skilled in the art that the present inventive embodiments may be practiced without these specific details. In other instances, well-known structures and devices may be shown in block diagram form in order to avoid unnecessarily obscuring the present inventive embodiments.

[00020] Referring to FIG. l, an exploded isometric view of a compact permanent magnet generator 100 in accordance with an exemplary embodiment is depicted. The compact permanent magnet generator 100 comprises a cylindrical stator assembly 20 and a rotor assembly 50. The stator assembly 20 includes a stationary ferromagnetic core 5 having inwardly projecting stator poles 15 uniformly spaced about an interior circumference of the stator assembly 20. A plurality of stator windings 10 are wound around successive stator poles 15 in order to provide a three phase alternating current output.

[00021] The rotor assembly 50 includes a shaft 30 mounted in axial rotational alignment within the stator assembly 20. A non-ferromagnetic drum 25 is axially coupled to the shaft 30 in which a longitudinal dimension of the non-ferromagnetic drum 25 is disposed in rotational proximity to the stator assembly 20. A plurality of permanent magnets 35 are slidably mounted proximate to an outer circumferential surface of the non-ferromagnetic drum 25 with sequentially alternating north/south magnetic polarities. In an exemplary embodiment, the shaft 30 may include a key slot 40 for receiving a locking key (not shown). The key slot 40 may be used for uniform alignment of the non-ferromagnetic drum 25 with the stator assembly 20.

[00022] The permanent magnets 35 are maintained proximate to an outer circumferential surface of the non-ferromagnetic drum 25 by a series of uniformly spaced slots 29. The slots 29 are dimensioned to receive and maintain the permanent magnets 35 in axial alignment with the stator poles 15 in a generally face-to-face spatial relationship. The permanent magnets 35 may further be maintained within the slots 29 of the non-ferromagnetic drum with retainer means 45, 45', 55, 60, 60'. The retainer means includes non-ferromagnetic fasteners 65, clips, retaining rings 45, 45' and/or temperature resistant epoxy. The use of retaining rings 45, 45' allows for simplified replacement of the permanent magnets 35 when their associated magnetic fields may become depleted.

[00023] The compact permanent magnet generator 100 typically utilizes rare earth permanent magnets 35 which provide a surface magnetic flux density greater than 5000 Gauss. For example, rare earth magnets using combinations of neodymium-iron- boron (NdFeB). For heat and mechanical protection, the permanents magnets 35 should preferably be encapsulated inside a non-ferromagnetic case and rated for 150 degrees Celsius. For example, a nickel-copper- nickel (NiCuNi) cladding. In an one exemplary embodiment, the permanent magnets 35 are configured as elongated bars constructed from the above listed rare earth and cladding materials. Alternately, rare earth permanent magnets constructed using samarium-cobalt (SmCo) may also be used. In an exemplary embodiment, fourteen neodymium-iron-boron rare magnets 35 are slidably disposed in the slots 29 of the non-ferromagnetic drum 25.

[00024] First and second stator housing covers 75, 75' are provided at opposing axial ends of the stator assembly 20. The stator housing covers 75, 75' may be ventilated or unventilated depending on the particular design implementation. The first and second stator housing covers 75, 75'and/or drum 25 may be constructed from any suitable non-ferromagnetic material. By way of example and not limitation, aluminum or an aluminum alloy using milling and/or die cast techniques known in the relevant art. Front and rear bearings 70, 70' are provided to allow free axial rotation of the rotor assembly 50. The front and rear bearings 70, 70' may be pressed into suitably dimensioned apertures included in the first and second stator housing covers 75, 75'. The compact permanent magnet generator 100 may be assembled using opposing axial rings 60, 60' and common fasteners 65, 80, 80'. One skilled in the art will appreciate that other assembly mechanisms known in the relevant may be used as well.

[00025] Referring to FIG.2, a cross-sectional view of a stator assembly 20 in accordance with an exemplary embodiment is depicted. The stator assembly 20 includes a stationary ferromagnetic core 5 having inwardly projecting stator poles 15 uniformly spaced about an interior circumference of the stator assembly 20. The ferromagnetic core 5 is cylindrical in shape and comprised of a longitudinal stack of ferromagnetic disks 205 (FIG.2A). The ferromagnetic disks 205 (FIG.2A) are typically constructed of steel or like ferromagnetic metal with varnish or other suitable surface lamination materials. Each ferromagnetic disk 205 (FIG.2B) includes a center circular aperture 210 (FIG.2B) dimensioned to axially receive the rotor assembly 50 therethrough. The diameter of the circular aperture 210 (FIG.2B) is determined by the diameter of the rotor assembly 50 with sufficient clearance to account for thermo- expansion, axial dimensional tolerances and off-axis rotational variations of the rotor assembly 50 under load.

[00026] Each ferromagnetic disk 205 (FIG.2B) includes a plurality of uniformly spaced stator winding apertures 215 in communication with the center aperture 210 (FIG.2B). Each stator winding aperture 215 includes a horseshoe shape. The stator winding apertures 215 are dimensioned to receive stator windings 10 (FIG.l) therethrough. The adjoining metal walls of the stator winding apertures 215 (FIG.2B) form "T" shaped stator poles 15. The tops of the "T's" face inward toward the geometric center of each ferromagnetic disk 205 and present a predominate stator pole face for magnetically interacting with the permanent magnets 35 included with the rotor assembly 50. One skilled in the art will appreciate that the shape of the stator winding apertures 215 (FIG.2B) and/or stator poles 15 may be varied to achieve a particular design objective. The ferromagnetic disks 205 (FIG.2B) are typically laser cut using precision machining equipment known in the relevant art.

[00027] The stator windings 10 (FIG.l) are typically constructed from a suitable gauge of enameled copper wire. The copper wire may be either solid, stranded, hollow and/or combinations thereof to arrive at the suitable wire gauge for safely handling electrical energy induced in the stator windings 10 (FIG.l). The stator windings 10 (FIG. l) are wound around the stator poles 15 using the stator winding apertures 215 (FIG.2B) as wire guides. The number of turns of the stator windings 10 and winding pattern are discussed below. In this exemplary embodiment, the stator windings 10 are wound 10A, 10B, IOC for three phase alternating current output. The stator assembly 20 may be held together by periodically spaced fasteners 65 (FIG.l) longitudinally extending through the stack of ferromagnetic disks 205 (FIG.2A) and compressed together with opposing axial rings 60, 60' (FIG.l).

[00028] Referring to FIG.3, a side view of a rotor assembly 50 in accordance with an exemplary embodiment is depicted. The rotor assembly 50 includes a cylindrical shaft 30 mounted in axial rotational alignment within the stator assembly 20 (FIG. l). The shaft 30 is typically conducted of a high grade steel, although other suitable materials may be used as well. The shaft 30 is configured to be mechanically rotated by an external motivation source. The shaft 30 is longitudinally dimensioned to at least span the width of the stator assembly 20 (FIG.l) plus sufficient longitudinal dimensions for axial rotational support and engagement of the external motivation source. For example, an internal combustion or turbine engine. Axially, the shaft 30 is generally dimensioned to support the rotor assembly 50 under both static and dynamic operating conditions without sagging or bowing.

[00029] A non-ferromagnetic drum 25 is axially coupled to the shaft 30. The non- ferromagnetic drum 25 may be coupled to the shaft using common fasteners, preferably non-ferromagnetic (e.g., austenitic stainless steel, titanium alloys, etc.), pressed onto the shaft 30 with an interference fit and/or using key/key slot arrangements. The non-ferromagnetic drum 25 is generally cylindrically shaped and axially dimensioned to fit within the circular aperture 210 (FIG.2B) formed by the stator assembly 20 (FIG. l) Typically, the non-ferromagnetic drum 25 itself is constructed from an aircraft grade aluminum alloy (e.g., T6061, T6062, T6063). One skilled in the art will appreciate that other non-ferromagnetic metals may be used to obtain a particular design objective.

[00030] The longitudinal dimension of the non-ferromagnetic drum 25 is approximately equal to the longitudinal dimension of the stator assembly 20. A body section 38 of the non-ferromagnetic drum 25 which axially lies between an outer circumference of the non-ferromagnetic drum 25 and the shaft 30 may remain as a solid cylinder for preserving momentum (i.e., as a flywheel) or may be hollow with periodic axial members 39 for supporting the outer circumference of the non- ferromagnetic drum 25. The hollow embodiment of the non-ferromagnetic drum 25 allows for interior air circulation and forced air cooling of the stator assembly 20 and permanent magnets 35. Fan blades 37 may likewise be added to the periodic axial members 39 to aid in interior air movement and cooling.

[00031] The outer circumference of the non-ferromagnetic drum 25 includes a plurality of uniformly spaced slots 29. The slots 29 are dimensioned to receive and maintain the permanent magnets 35 in axial alignment with the stator poles 15 (FIG.2) in a generally face-to-face spatial relationship. The slots 29 are typically precision milled into an axial face of the non-ferromagnetic drum 25 to ensure that the maximum predominate surface areas of the permanent magnets 35 are available to magnetically interact with the stator poles 15 (FIG.2). The permanent magnets 35 are slidably 36 disposed within the slots 29 proximate to an outer circumferential surface of the non-ferromagnetic drum 25 in alternating north/south magnetic polarity (FIG.3). The slots 29 maintain the permanent magnets 35 beneath (i.e., axially inward) the surface of the outer axial circumference of the non-ferromagnetic drum 25.

[00032] Contralateral lips 26, 27 extending over minority portions of each of the slots 29 axially maintains the permanent magnets 35 within the slots 29 during operation of the compact permanent magnet generator 100. The permanent magnets 35 may further be maintained within the slots 29 of the non-ferromagnetic drum with retainer means 45, 45', 55, 55' (FIG.l). The retainer means includes non- ferromagnetic fasteners 65, clips and/or temperature resistant epoxy as discussed above. In an exemplary embodiment, spaces 28 may be provided beneath the permanent magnets 35 for bonding of the permanent magnets 35 with the non- ferromagnetic drum 25 using temperature resistant epoxy. The contralateral lips 26, 27 and the slots 29 form a fixture for maintaining the permanent magnets 35 within the non-ferromagnetic drum 25.

[00033] Referring to FIG.4, a partial isomeric view of a permanent magnet 35 aligned with a plurality of stator poles 15 A, 15B, 15C in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, the permanent magnet 35 is aligned approximately in juxtaposition with three stator poles 15A, 15B, 15C. Depending on the particular design configuration, the axial dimensions of the stator poles 15 A, 15B, 15C may be expanded or reduced to allow 2 through 3 stator poles 15A, 15B, 15C to be in juxtaposition with a single permanent magnet 35. Likewise, the axial dimensions of the permanent magnets 35 may be varied to accomplish a particular design objective. As depicted in this exemplary embodiment, the permanent magnet 35 is in a generally face-to-face spatial relationship with the stator poles 15 A, 15B, 15C. The general face-to-face spatial relationship aligns a predominate surface area of the permanent magnet 35 with a predominate axial surface area of the stator poles 15A, 15B, 15C. The stator windings 10 are partially shown wound around the stator poles 15A, 15B, 15C. Referring to FIG.4A, a close- up partial top view of a permanent magnet 35 aligned with a plurality of stator poles 15 A, 15B, 15C in accordance with an exemplary embodiment is depicted. Sufficient clearance 401 is provided between the non-ferromagnetic drum 25 and the stator poles 15 A, 15B, 15C to account for thermo-expansion, axial dimensional tolerances and off- axis rotational variations of the rotor assembly 50. [00034] Referring to FIG.4B, stator windings 10 in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, three sets 10A, 10B, IOC of stator windings 10 are wound around stator poles 15A, 15B, 15C in succession. The first stator winding 10A is wound around stator pole 15 A, followed by the second stator winding 10B wound around stator pole 15B. Stator winding IOC successively follows stator winding 10B and is wound around stator pole 15C. This sequence repeats with stator winding 10A wound around stator pole 15D, stator winding 10B wound around stator pole 15E and stator winding IOC wound around stator pole 15F. This sequence repeats throughout the stator core 5. In this exemplary embodiment, the stator windings 10 are wound around the successive stator poles 15A, 15B, 15C, 15D, 15E, 15F in order to provide three phase alternating current output. One skilled in the art will appreciate that other stator winding arrangements may be used to generate single phase or other multiphase alternating current output.

[00035] In an exemplary embodiment, the output from the stator windings 10 may be electrically filtered or externally rectified (not shown). The stator windings 10 may be wired in either a delta or Wye configuration as is necessary to meet a particular design objective. In one exemplary embodiment, each phase of the stator windings 10A, 10B, IOC is wound three and one-half turns around a stator pole 15 A, 15B, 15C in the succeeding order. Thus, each stator winding phase is wound around every fourth successive stator pole 15D, 15E, 15F. The stator winding directions are typically maintained uniform through out the stator windings. In one exemplary embodiment, forty- two stator poles 15 (FIG.2B) are provided. Scaling of the number of stator windings 10 may be accomplished as required to meet a particular design objective.

[00036] Referring to FIG.5, a side view of a compact permanent magnet generator 100 in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, the compact permanent magnet generator 100 includes a pair of non- ferromagnetic stator housing covers 75, 75' axially disposed at opposing longitudinal surfaces of the stator assembly 20. The stator housing covers 75, 75' include axial bearings 70, 70' (not visible) which support axial rotation of the shaft 30 and maintains proper axial alignment with the stator assembly 20. The stator housing covers 75, 75 are typically constructed from aircraft grade aluminum alloys (T6061, T6062, T6063). Referring to FIGS.5A & 5B, front and rear end views of a compact permanent magnet generator 100 in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, a plurality of ventilation ports 505, 505' are provided to allow air circulation through the compact permanent magnet generator 100.

[00037] In another exemplary embodiment, one or more collection coil(s) 510 are disposed along an exterior of one or more the stator housing covers 75' . The collection coil(s) 510 are generally aligned tangential to an outer circumferential surface of the non-ferromagnetic drum 25 (FIG.2) This alignment places the collection coil(s) 510 tangential to an outer circumferential rotational path traveled by the non- ferromagnetic drum 25 (FIG.l) during operation of the compact permanent magnet generator 100. The collection coil(s) 510 are preferably aligned perpendicular to longitudinal ends of the permanent magnets 35 (FIG.2). An aperture 515 is provided in either the first or second stator housing covers 75, 75' to allow wires carrying the generated electricity to be connected to an electrical load, control circuitry or electrical energy storage device.

[00038] Referring to FIG. 6, an electrical circuit for collection coil(s) 510 in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, one or more collection coil(s) 510 are affixed to an external surface of a non-ferromagnetic stator housing cover 75' (FIG.5A). The collection coil(s) 510 are configured to capture non-axial magnetic flux leaked from the compact permanent magnet generator 100 during operation. The collection coils 510 comprise several turns (20 - 40) of light gauge enameled magnet wire (e.g., AWG #18 - 22) wound around a hollow ferrite cylinder. Off-axis magnetic flux is intercepted by the stationary collection coil(s) 510 which causes a current to flow in the windings of the collection coil(s) 510. The electrical current generated by each collection coil 510 is then rectified 605 and stored in an electrical energy storage device 600, for example a battery or capacitor. Full wave rectification 605 is shown, however, this is optional. The output current from the collection coil(s) 510 individually is relatively small, but may be sufficient for many lower power consumption applications. For example, powering a small coolant pump. The diameter of the collection coil(s) 510 is not critical. Typical diameters range from 1 to 2 inches in diameter when wound around the hollow ferrite cylinder(s). [00039] Referring to FIG.7A, an external stator cooling arrangement 705 in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, the compact permanent magnet generator 100 may be equipped with a stator cooling assembly 705 in thermal communication with the stator assembly 20. The stator cooling assembly 20 includes a plurality of turns of a non-ferromagnetic metal conduit, typically aluminum, austenitic stainless steel or copper, axially wound around an exterior surface of the stator assembly 20. Heat generated internally during operation of the generator 100 is thermally conducted through the stator assembly 20 and captured by a fluid flowing 710, 715 through the non-ferromagnetic metal conduit.

[00040] Referring to FIG.7B, an internal stator cooling arrangement 720 in accordance with an exemplary embodiment is depicted. In this exemplary embodiment, the stator cooling assembly 720 includes a plurality of turns of a non- ferromagnetic metal conduit longitudinally incorporated into the stator assembly 20. Heat generated internally during operation of generator 100 is thermally conducted through the stator assembly 20 and into the longitudinal conduits where a coolant flowing 710, 715 within the conduit removes the heat from the stator assembly 20. In either exemplary embodiment (FIG.7A, 7B) external cooling of the heated fluid may be accomplished used a heat exchanger (not shown). The fluid used as a coolant may be either a liquid, a gas or multiphase coolant. Examples of commonly known coolants include water, helium, nitrogen, sodium, chlorofluorocarbons and ammonia.

[00041] Examples of suitable uses for the he compact permanent magnet generator 100 include but are not limited to installation in motor vehicles, aircraft, spacecraft, stationary and/or portable power generators. With suitable scaling of the windings 10 (FIG.2), number of stator poles 15 (FIG.2) and/or permanent magnets 35 (FIG.2), the compact permanent magnet generator 100 may be adapted for wind turbine and/or hydroelectric electrical power generation.

[00042] The various exemplary inventive embodiments described herein are intended to be merely illustrative of the principles underlying the inventive concept. It is therefore contemplated that various modifications of the disclosed embodiments will, without departing from the inventive spirit and scope, be apparent to persons of ordinary skill in the art. They are not intended to limit the various exemplary inventive embodiments to any precise form described. In particular, it is contemplated that the compact permanent magnet generator and related components may be constructed from any suitable material. No specific limitation is intended to a particular construction material, order or sequence described. Other variations and inventive embodiments are possible in light of above teachings, and it is not intended that this Detailed Description limit the inventive scope, but rather by the Claims following herein.

Claims

CLAIMS What is Claimed:

1. A compact permanent magnet generator comprising:

a stator assembly including a stationary ferromagnetic core having inwardly projecting stator poles uniformly spaced about an interior circumference of the stator assembly;

first, second and third stator windings periodically wound around succeeding stator poles;

a rotor assembly including a shaft mounted in axial rotational alignment within the stator assembly and a non-ferromagnetic drum axially coupled to the shaft;

a plurality of uniformly spaced permanent magnets maintained within longitudinally aligned slots provided proximate to an outer circumferential surface of the non-ferromagnetic drum;

each of the permanent magnets having a predominate surface area aligned in juxtaposition with at least two of the uniformly spaced stator poles such that an electrical current will be induced in the first, second and third stator windings upon rotation of the rotor assembly.

2. The compact permanent magnet generator of Claim 1 wherein each of the permanent magnets provides a surface magnetic flux density greater than 5000

Gauss.

3. The compact permanent magnet generator of Claim 1 wherein the non- ferromagnetic drum is constructed from an aluminum alloy.

4. The compact permanent magnet generator of Claim 1 wherein each of the permanent magnets is formed in an elongated shape.

5. The compact permanent magnet generator of Claim 4 wherein the slots are dimensioned to slidably receive the elongated shaped permanent magnets.

6. The compact permanent magnet generator of Claim 1 further comprising non-ferromagnetic stator housing covers coupled to opposing axial surfaces of the stator assembly.

7. The compact permanent magnet generator of Claim 1 wherein the non- ferromagnetic drum further includes contralateral lips extending over minority portions of each of the slots.

8. The compact permanent magnet generator of Claim 1 wherein a longitudinal dimension of the non-ferromagnetic drum is less than a diameter of the non-ferromagnetic drum.

9. The compact permanent magnet generator of Claim 1 further comprising:

a collection coil aligned tangential to the outer circumferential surface of the non-ferromagnetic drum for capturing non-axial magnetic flux and converting the captured non-axial magnetic flux into an electrical current.

10. The compact permanent magnet generator of Claim 7 wherein the contralateral lips form a fixture for axially maintaining the plurality of permanent magnets within the non-ferromagnetic drum.

11. A compact permanent magnet generator comprising:

each of the permanent magnets having a predominate surface area aligned in juxtaposition with no more than three of the uniformly spaced stator poles such that an electrical current will be induced in the first, second and third stator windings upon rotation of the rotor assembly;

a non-ferromagnetic stator housing cover coupled to axial surface of the stator assembly;

a collection coil affixed to an external surface of the non-ferromagnetic stator housing cover, the collection coil aligned tangential to the outer circumferential surface of the non-ferromagnetic drum and in approximate rotational alignment with longitudinal ends of the permanent magnets.

12. The compact permanent magnet generator of Claim 11 wherein the collection coil is configured to capture non-axial magnetic flux and convert the captured non-axial magnetic flux into an electrical current.

13. The compact permanent magnet generator of Claim 11 further comprising a rectifier circuit coupled with the collection coil and an electrical energy storage device.

14. The compact permanent magnet generator of Claim 13 wherein the rectifier circuit is configured to rectify the electrical current generated by the collection coil and output rectified electrical current to an electrical energy storage device.

15. A compact permanent magnet generator comprising:

a stator assembly including a stationary ferromagnetic core having forty-two inwardly projecting stator poles uniformly spaced about an interior circumference of the stator assembly;

fourteen uniformly spaced permanent magnets maintained within longitudinally aligned slots provided in an outer circumferential surface of the non- ferromagnetic drum;

each of the permanent magnets having a predominate surface area aligned in juxtaposition with no more than three of the uniformly spaced stator poles such that an electrical current will be induced in the first, second and third stator windings upon rotation of the rotor assembly.

16. The compact permanent magnet generator of Claim 15 further comprising:

a stator cooling assembly in thermal communication with the stator assembly.

17. The compact permanent magnet generator of Claim 16 wherein the stator cooling assembly is integrated into the stator assembly.

18. The compact permanent magnet generator of Claim 16 wherein the stator cooling assembly comprises:

a plurality of turns of a non-ferromagnetic metal conduit axially wound around an exterior surface of the stator assembly.

19. The compact permanent magnet generator of Claim 15 further comprising:

a collection coil disposed on an axial end of the compact permanent magnet generator and aligned tangential to the outer circumferential surface of the non- ferromagnetic drum.

20. The compact permanent magnet generator of Claim 15 wherein each of the first, second and third stator windings periodically wound around succeeding stator poles equals three and one-half turns.