REGULATABLE ALTERNATOR

• US 3,671,788 A
• Filed: 11/30/1970
• Issued: 06/20/1972
• Est. Priority Date: 11/30/1970
• Status: Expired due to Term

• Current Assignee: Charles H. White, Louis I. Knudson, Richard C. Frink
• Original Assignee: Charles H. White, Louis I. Knudson, Richard C. Frink
• Inventors: Louis, I. Knudson, Richard, C. Frink, Charles, H. White
• Primary Examiner(s): Lewis H. Myers
• Assistant Examiner(s): H. Huberfeld
• Application Number:
  US05/093,582
• Time in Patent Office: 568 Days
• Field of Search: 322/51,52,57 310/179,156,210
• US Class Current: 310/156.55
• CPC Class Codes: H02K 21/046 with rotating permanent magnets and stationary field winding
• CPC Class Codes: H02K 21/16 having annular armature cores with salient poles with homopolar co-operation H02K21/20
• CPC Class Codes: H02P 9/40 by variation of reluctance of magnetic circuit of generator

Abstract

An alternator comprising a permanent magnet rotor constructed to retain circumferentially polarized permanent magnets in place without substantial stress on the magnet material. A stator cooperating with the rotor is constructed to permit regulation of the alternator output by the use of a control winding which may saturate part of the magnetic circuit in the stator. The magnetic structure of the stator includes an annular magnetic circuit means with inwardly projecting teeth. Each tooth is separated into at least two axially separated radial branches. The annular magnetic circuit means and the teeth define magnetic return circuits for the flux from the poles on the rotor. Each pair of axially spaced tooth branches is bridged at its inner and outer ends by magnetic members, which together with the two tooth sections define a magnetic loop circuit. The control winding encircles the stator inside the magnetic loop circuits. Application of current to the control winding produces a flux which cooperates with the alternating flux from the rotor pole to saturate one of the two parallel teeth, while leaving the other unsaturated. Thus, the saturation and hence the reluctance of the magnetic circuit in the stator is controlled but there is always present an unsaturated magnetic return circuit interrupted only by the air gaps at the stator periphery.

Claims

1. An alternator, comprising:

a. a permanent magnet rotor having peripheral poles alternately of opposite polarities; and

b. a stator cooperating with said rotor and including;

1. annular magnetic circuit means;

2. a plurality of tooth means projecting radially inwardly from the annular means;

3. output winding means; and

4. control winding means;

wherein the improvement comprises;

c. each said tooth means comprises a set of at least two parallel axially spaced radial branches and a pair of branches parallel to the rotor axis and connecting the ends of the parallel axially spaced radial branches, said sets of radial branches defining at least two axially spaced circumferential rows of radial branches;

d. the radial branches cooperate with at least a portion of the annular magnetic circuit means to define a magnetic return circuit for flux emanating from the poles on the rotor;

e. said output winding means includes output windings encircling at least some of the radial branches;

f. said control winding means extend circumferentially of the stator between the two rows of parallel axially spaced raDial branches, so that each pair of axially spaced radial branches and their connecting branches define one of a plurality of magnetic loop circuits for flux produced by said control winding means; and

g. each set of radial branches is connected in both said magnetic return circuit and in one of said loop circuits;

each radial branch being subject to an alternating magnetomotive force during rotation of the rotor, said alternating magnetomotive force being effective to produce alternating flux in at least some of the radial branches, each set of radial branches being subject to a unidirectional magnetomotive force when unidirectional current flows in the control winding, said unidirectional magnetomotive force being effective to produce unidirectional flux in the loop circuits which acts in opposite radial directions in two branches of the set, said radial branches being dimensioned to be saturable by the sum of the return circuit flux and the loop circuit flux, so that an increase of said direct current in the control winding is effective to increase the flux in at least some of the radial branches and thereby to saturate said branches and increase the effective reluctance of the magnetic return circuit, reducing the flux therein and the current induced thereby in said output winding.

2. An alternator as defined in claim 1, in which there are only two parallel radial branches in each set.

3. output winding means;

and

4. An alternator as defined in claim 2, including:

a. short-circuited windings on one radial branch of each set, and on alternate radial branches of each circumferential row.

5. An alternator as defined in claim 1, in which:

a. said tooth means comprises three radial branches in each set; and

b. said control winding means includes two windings, each extending circumferentially of the stator and located between two circumferential rows of radial branches.

6. An alternator as defined in claim 5, including a short-circuited coil on the center branch of alternate sets of radial branches, and on both end branches of the other sets.

7. An alternator as defined in claim 6, in which said output winding means comprises output coils only on the end branches of sets whose center branch carries a short-circuited winding.

8. An alternator as defined in claim 1, in which said rotor comprises:

a. a central cylindrical support member;

b. a plurality of circumferentially spaced permanent magnets, which are polarized with their poles directed circumferentially, and alternately in opposite directions;

c. a plurality of magnetically permeable segments between said magnets and projecting radially outward beyond said magnets;

d. a plurality of non-magnetic retaining bars, one located radially outward from each magnet and circumferentially aligned with said segments; and

e. means to hold the magnets, the segments and the retaining bars in place on the support member, including a pair of end plates fixed on said fixed central cylindrical support member and having their peripheral margins engaging shoulders on said segments and retaining bars.

9. An alternator as defined in claim 8, in which said support member is hollow and includes a central sleeve extending through said support member and said end plates, said sleeve having a shoulder at one end abutting against one of said end plates and having its opposite end deformed to engage the outside of the other end plate, to hold the rotor assembled.

10. A rotor for a permanent magnet alternator, comprising:

a. a central cylindrical support member;

b. a plurality of circumferentially spaced permanent magnets, which are polarized with their poles directed circumferentially, and alternately in opposite directions;

c. a plurality of magnetically permeable segments between said poles and projecting radially outward beyond said poles;

d. a plurality of Non-magnetic retaining bars, one located radially outward from each pole and circumferentially aligned with said segments; and

e. means to hold the magnets, the segments and the retaining bars in place on the support member, including a pair of end plates fixed on said central cylindrical support member and having their peripheral ends engaging said segments and retaining bars.

11. A rotor as defined in claim 10, in which said magnets are axially shorter than said retaining bars, and including spacer means of malleable material between the end plates and the magnets and retained by said retaining bars.

12. An alternator, comprising:

a. a permanent magnet rotor having peripheral poles alternately of opposite polarities; and

b. a stator cooperating with said rotor and including;