Permanent magnet generator apparatus including a consequent pole rotor

• US 4,777,397 A
• Filed: 08/15/1986
• Issued: 10/11/1988
• Est. Priority Date: 08/15/1986
• Status: Expired due to Term

• Current Assignee: Marathon Electric Manufacturing Corporation Wausau Wisconsin
• Original Assignee: RBC Manufacturing Corp. (Regal Rexnord Corp.)
• Inventors: Parshall, Millis V.
• Primary Examiner(s): Salce, Patrick R.
• Assistant Examiner(s): Rebsch, D. L.
• Application Number:
  US06/897,133
• Time in Patent Office: 788 Days
• Field of Search: 310/42, 310/43, 310/153, 310/156, 310/187, 310/186, 310/216, 310/217, 310/218, 310/261, 310/181, 29/598
• US Class Current: 310/156.15
• CPC Class Codes: H02K 1/2746 the rotor consisting of magnets arranged with the same polarity, e.g. consequent pole type
• CPC Class Codes: H02K 1/278 Surface mounted magnets; Inset magnets
• CPC Class Codes: H02K 19/38 Structural association of synchronous generators with exciting machines

Abstract

A permanent magnet generator has a laminated rotor mounted to the driven shaft of a power alternator. The rotor is cylindrical and includes 10 circumferentially distributed elongated axial slots and 10 rotor teeth. Iron-boron-neodymium rare earth magnets are secured within each of the slots, radially and similarly polarized. The magnet and teeth define a consequent 20 pole rotor with a minimum number of magnets. The rare earth magnets are epoxy bonded within each of the corresponding slots. Each slot has a rectangular cross-section with slightly flared sides. The epoxy extends between the recess surfaces and the magnets. The flared sides improve the flux distribution. The outer radial ends of the magnets spaced inwardly of the rotor teeth prevent mechaical damage to the magnets. The outside maximum dimension of the PMG stator is slightly less than the inner diameter of the exciter stator for convenient removal through the bore of the exciter.

Claims

1. A permanent magnet generator rotor adapted to be mounted within a stator having a cylindrical surface, comprising a cylindrical rotor core having a plurality of circumferentially spaced rotor poles having cylindrical outer surfaces with a diameter slightly less than said stator and defining slots extending longitudinally of the rotor core, each of said slots having an essentially constant circumferential width throughout the inner portion of the slot and with the outer portions of the slot flared outwardly, a permanent magnet formed of a rare earth magnetic material secured within each of said slots with a radially outer exposed surface extended over the width of said inner portion of the slots, said radially outer exposed surface of each of said magnets totally located radially inwardly of the cylindrical outer surface of the rotor core over the complete width of said slot by a depth only required to prevent engagement with the stator cylindrical surface.

2. A permanent magnet generator rotor adapted to be mounted within a stator having a cylindrical surface, comprising a cylindrical rotor core having a plurality of circumferentially spaced rotor poles having cylindrical outer surfaces with a diameter slightly less than said stator and defining slots extending longitudinally of the rotor core, each of said slots having an essentially constant circumferential width throughout the slot, a permanent magnet formed of a rare earth magnetic material secured within each of said slots with a radially outer exposed surface extended over the width of the slot, said radially outer exposed surface of each of said magnets totally located radially inwardly of the cylindrical outer surface of the rotor core over the complete width of said slot by a depth only required to prevent engagement with the stator cylindrical surface, wherein each of said slots includes a substantially flat base and sidewalls including a first inner portion and a second outer portion flaring outwardly and laterally, said magnets having parallel flat sidewalls and a width slightly less than the width of said slot.

3. A permanent magnet generator rotor adapted to be mounted within a stator having a cylindrical surface, comprising a cylindrical rotor core having a plurality of circumferentially spaced rotor poles having cylindrical outer surfaces with a diameter slightly less than said stator and defining slots extending longitudinally of the rotor core, each of said slots having an essentially constant circumferential width throughout the slot, a permanent magnet formed of a rare earth magnetic material secured within each of said slots with a radially outer exposed surface extended over the width of the slot, said radially outer exposed surface of each of said magnets totally located radially inwardly of the cylindrical outer surface of the rotor core over the complete width of said slot by a depth only required to prevent engagement with the stator cylindrical surface, including an adhesive interposed between said magnets and all opposed surfaces of said slots, said adhesive securing said magnets in said slots.

4. The generator rotor of claim 3 wherein said rotor poles have a circumferential width less than that of said slots.

5. The generator rotor of claim 4 wherein the sidewalls of said poles and slots have an outer portion which flares circumferentially to produce an enlarged opening to said slot.

6. The generator rotor of claim 5 wherein said rare earth magnetic material is iron-boron-neodymium.

7. The generator rotor of claim 3 wherein said rare earth magnetic material is iron-baron-neodymium.

8. A permanent magnet generator rotor apparatus, comprising a cylindrical rotor core having a plurality of circumferentially spaced outwardly flared surface slots extending axially of the rotor core, a rectangular permanent magnet secured within each of said slots, each of said magnets being a solid magnet formed of iron-boron-neodymium and being similarly located radially inwardly of the outer cylindrical surface of the rotor core, and including an adhesive in each slot interposed between said magnets and opposed surfaces of said slot, said adhesive forming the sole support of said magnets in said rotor core.

9. A regulated alternator unit comprising a support base structure, an alternator having a rotating field rotor including a shaft, a bearing means secured to one end of said alternator, said shaft extending from said bearing means, a permanent magnet generator having a rotor secured to said shaft immediately outboard of said bearing means and a stator mounted to said base structure, said rotor having a plurality of circumferentially spaced surface slots extending longitudinally of the rotor, a permanent magnet formed of a rare earth magnetic material secured within each of said slots, and an exciter having a rotor secured to the shaft outboard of said generator and having a exciter stator secured to said base structure, said exciter stator having a rotor opening of a diameter in excess of the maximum width of said stator of said generator.

10. The regulated alternator unit of claim 9 wherein an epoxy adhesive is interposed between said magnets and opposed surfaces of said slots, said epoxy adhesive forming the sole support of said magnets in said rotor.

15. The regulated alternator unit of claim 9 wherein said magnets have an outer surface spaced radially inwardly of the outer cylindrical surface of the rotor.

11. A regulated alternator unit comprising an alternator having a rotating field rotor including a shaft and an excitation winding unit, a permanent magnet generator having a permanent magnet rotor secured to said shaft, said rotor having a lamination core of single piece laminations and having a plurality of circumferentially spaced rotor teeth defining surface slots extending axially of the rotor, a permanent magnet secured within each of said slots and said magnets having the same radial polarization and exposed outer surfaces and with the adjacent rotor teeth defining a consequent pole generator, said generator having an output winding connected to said excitation winding unit to excite said alternator.

12. The regulated alternator unit of claim 11 wherein said magnets have an outer surface spaced radially inwardly of the outer cylindrical surface of the rotor teeth.

13. The regulated alternator unit of claim 11 wherein an adhesive is interposed between said magnets and opposed surfaces of said slots, said adhesive supporting said magnets in said rotor.

14. A permanent magnet generator rotor, comprising a cylindrical lamination rotor core of single piece laminations having a plurality of circumferentially spaced rotor poles defining slots extending axially of the rotor core, and permanent magnets secured within each of said slots and said magnets each having the same radial polarization and exposed outer surfaces to form a consequent pole rotor for a permanent magnet rotor machine, including an adhesive interposed between said magnets and opposed surfaces of said slots and securing said magnets in said slots.