# US 4,394,595 A · Stator arrangement for a synchronous motor

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- Number: US 4,394,595 A
- Document ID: US4394595A
- Status: Granted
- Kind: A
- Application number: 06/185,330
- Filed: 1980-09-08
- Granted: 1983-07-19
- Earliest claimed: 1978-12-04
- Assignees: Emhart Industries, Inc.
- Inventors: Robert F. Weaver
- Web page: https://patentgrep.com/patent/US4394595A

## CPC

- H02K 21/12: with stationary armatures and rotating magnets
- H02K 2201/12: Transversal flux machines
- Y10T 29/49009: Dynamoelectric machine
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A synchronous motor wherein a field coil is positioned adjacent to a rotor and stator assembly in a side-by-side relationship has a stator pole arrangement to compensate for flux phase differences caused by the side-by-side arrangement.

## Claims

### Claim 1

A method of providing good starting characteristics in a synchronous motor which includes inter-meshed stator poles and a permanent magnet rotor with rotor poles rotating with said inter-meshed stator poles and wherein a field coil which generates flux to cause said rotation of said rotor is disposed adjacent said inter-meshed stator poles in a side-by-side relationship, the method comprising:
(a) providing shading means for a predetermined number of said stator poles to provide a group of shaded poles and a group of unshaded poles,
(b) selecting a reference pole from each of said groups,
(c) determining the flux phase difference between said reference pole and individual poles of a group,
(d) converting said phase difference to a mechanical angle and locating said individual poles with respect to each other according to said mechanical angle.

### Claim 2 (depends on 1)

A method according to claim 1 wherein said flux phase difference is determined by comparing difference from a common flux source.

### Claim 3 (depends on 2)

A method according to claim 2 wherein said common flux source is a core of said field coil.

### Claim 4 (depends on 1)

A method according to claim 1 wherein said phase difference is converted to said mechanical angle in accordance with the formula:
E=2.DELTA.n/N,
wherein
E=correction from 180.degree. electrical degree location in mechanical degrees
.DELTA.n=phase difference in electrical degrees (measured)
N=number of rotor and stator poles combined.

### Claim 5 (depends on 1)

A method according to claim 1 wherein the unshaded and shaded groups of stator poles are angularly shifted with respect to each other based on an average phase shift produced by said shading means.

### Claim 6

In a self-starting synchronous motor wherein a permanent magnet rotor having rotor poles rotates within an assembly of inter-meshed stator poles in response to flux generated by a field coil that is disposed adjacent to said assembly in a side-by-side relationship an improvement comprising:
(a) shading means electrically coupled to a predetermined number of stator poles to provide a group of shaded stator poles and a group of unshaded poles, and
(b) individual poles of each group offset from a reference pole by a mechanical angle determined by a flux phase difference between said reference pole and individual poles of each group.

### Claim 7 (depends on 6)

In a self-starting synchronous motor according to claim 6 said mechanical angle is determined by the formula:
E=2.DELTA.n/N;
wherein
E=correction from 180 electrical degree location in mechanical degree
.DELTA.n=phase difference in electrical degrees (measured)
N=number of rotor and stator poles combined.