Permanent magnet motor with absolute rotor position detection

Patent metadata

Field	Value
Publication number	US-10284121-B2
Application number	US-201615335522-A
Country	US
Kind code	B2
Filing date	Oct 27, 2016
Priority date	Sep 29, 2016
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

An IPM motor in which the absolute position of the rotor may be determined is disclosed. The IPM motor includes asymmetries in both the rotor and the stator. The rotor includes an asymmetrical pole configuration for one of the pole pairs in the rotor, and the stator includes a different number of turns for each winding of one phase of the motor. The different number of turns on each winding causes a different magnitude of flux to be generated with each winding. The flux interacts with the asymmetrical pole pair to identify to which winding the asymmetrical pole is proximate. A position sensing routine identifies an angular position with respect to each winding. The position sensing routine, in combination with the flux interaction between the windings and the asymmetrical pole provide an absolute position of the rotor within the IPM motor.

First claim

We claim:

1. A system for determining an absolute, mechanical position of a permanent magnet (PM) motor, the system comprising:
a stator in the PM motor having a plurality of windings and an outer periphery, wherein each winding includes a plurality of turns of an electrical conductor; and
a rotor in the PM motor having a plurality of pole pairs, wherein each pole pair includes a primary set of magnets operable to interact with a current conducted in the plurality of windings to cause rotation of the rotor, wherein:
the motor includes a plurality of segments, wherein each of the plurality of segments extends along a continuous arc defining a portion of the outer periphery of the stator;
the plurality of windings are distributed within each of the plurality of segments;
a number of turns for the plurality of turns for each winding within each segment is the same;
the number of turns for the plurality of turns for each winding in different segments is different;
the plurality of pole pairs are distributed within each of the plurality of segments; and
the pole pairs within a first segment, selected from the plurality of segments includes an asymmetry with respect to the pole pairs in the other segments, wherein the pole pairs in the first segment have a different magnetic structure than the pole pairs in the other segments.

2. The system of claim 1 wherein the different magnetic structure is a secondary set of magnets.

3. The system of claim 1 further comprising a power converter operatively connected to the PM motor to provide at least one of a regulated voltage and a regulated current to the plurality of windings in the stator to control rotation of the rotor.

4. The system of claim 3 wherein:
the power converter is operable to execute a first position detection module, a second position detection module, and a continuous position module,
the first position detection module determines a position of the rotor within one of the plurality of segments,
the second position detection module determines within which of the plurality of segments the pole pairs including the secondary set of magnets is located, and
the continuous position module determines the absolute, mechanical position of the PM motor as a function of the position of the rotor within one of the plurality of segments and of the segment within which the pole pairs including the secondary set of magnets is located.

5. The system of claim 4 wherein the power converter executes a commissioning module on power up to determine the absolute, mechanical position of the PM motor.

6. The system of claim 1 further comprising a multi-turn device generating a signal corresponding to one of a plurality of rotations of the rotor.

7. A system for determining an absolute, mechanical position of a permanent magnet (PM) motor, the system comprising:
a stator in the PM motor having a plurality of windings for each phase of input power to the PM motor distributed around the stator, wherein each winding includes a plurality of turns of an electrical conductor and wherein a number of turns for each winding for one of the phases is different; and
a rotor in the PM motor having a plurality of pole pairs, wherein one of the plurality of pole pairs is different than the other pole pairs; and
a power converter operatively connected to the PM motor to provide at least one of a regulated voltage and a regulated current to the plurality of windings in the stator to control rotation of the rotor, wherein:
the power converter is operable to execute a first position detection module, a second position detection module, and a continuous position module,
the first position detection module determines an electrical position of the rotor,
the second position detection module determines next to which of the plurality of windings, distributed around the stator, the pole pair that is different is located, and
the continuous position module determines the absolute, mechanical position of the PM motor as a function of the electrical position determined by the first position detection module and of the winding next to which the pole pair that is different is located as determined by the second position detection module.

8. The system of claim 7 , wherein the PM motor includes a plurality of segments;
the plurality of windings for each phase are distributed between the plurality of segments;
the number of turns for each winding within each segment is the same; and
the number of turns for each winding in a first segment selected from the plurality of segments is different than the number of turns for each winding in other segments of the plurality of segments.

9. The system of claim 8 wherein:
the plurality of pole pairs are distributed within each of the plurality of segments;
each of the pole pairs includes a primary set of magnets; and
the pole pair that is different than the other pole pairs includes a secondary set of magnets.

10. The system of claim 7 wherein the power converter executes a commissioning module on power up to determine the absolute, mechanical position of the PM motor.

11. The system of claim 7 further comprising a multi-turn device generating a signal corresponding to one of a plurality of rotations of the rotor.

12. A method for determining an absolute, mechanical position of a permanent magnet (PM) motor, wherein: the PM motor includes a rotor and a stator and has a plurality of segments distributed around the PM motor, each segment spans an equal distance around the PM motor, the rotor has a plurality of pole pairs, and a first pole pair includes a first asymmetry not present in the other pole pairs; the method comprising the steps of:
determining a first position of the rotor of the PM motor with respect to one of the plurality of segments with a first position detection module operative within a power converter controlling operation of the PM motor;
determining a second position of the rotor of the PM motor with a second position detection module operative on the power converter, Wherein the second position detection module identifies one of the plurality of segments, selected from the plurality of segments, within which the first pole pair is located and wherein a second asymmetry is located in the stator and the second position is determined as a function of the first asymmetry and the second asymmetry; and
determining the absolute, mechanical position of the PM motor with a continuous position module operative on the power converter as a function of the first position and the second position.

13. The method of claim 12 wherein each of the plurality of pole pairs includes a primary set of magnets and the pole pair with the first asymmetry includes a secondary set of magnets.

14. The method of claim 13 wherein:
the stator includes at least one winding within each of the plurality of segments,
each winding within one of the segments has an equal number of turns, and
the second asymmetry is defined by a different number of turns in the windings in a first segment, selected from the plurality of segments, than the number of turns in the windings in each of the other segments, selected from the plurality of segments.

15. The method of claim 12 wherein the power converter executes a commissioning module on power up to determine the absolute, mechanical position of the PM motor.

16. The method of claim 12 further comprising the steps of:
reading a third position of the rotor from a multi-turn device corresponding to one of a plurality of rotations of the rotor; and
determining the absolute, mechanical posit

Assignees

• Rockwell Automation Tech Inc

Inventors

• Sun Xikai
• Sizov Gennadi
• Schmidt Robert H

Classifications

• H02P23/14

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• H02P21/18

  Estimation of position or speed · CPC title

• H02P6/18 Primary

  without separate position detecting elements · CPC title