System and methods of electric machine rotor position detection

Patent metadata

Field	Value
Publication number	US-10404108-B2
Application number	US-201414310847-A
Country	US
Kind code	B2
Filing date	Jun 20, 2014
Priority date	Jun 20, 2014
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

An electric machine includes a stator assembly defining a longitudinal axis. The stator assembly includes a substantially cylindrical stator core that is concentric with and extends longitudinally along the longitudinal axis. The stator core includes a stator pole having an inner surface spaced radially outward from the longitudinal axis. The stator pole includes a first aperture extending radially outward from the inner surface of the stator pole. The electric machine also includes a rotor assembly rotatable about the longitudinal axis. The rotor assembly includes a rotatable shaft and a rotor core. The rotor core is concentric with and extends longitudinally along the longitudinal axis. The rotor core also includes a rotor pole including an outer surface spaced radially outward from the longitudinal axis. The outer surface is spaced radially inward from the stator pole inner surface.

First claim

What is claimed is:

1. An electric machine comprising:
a stator assembly defining a longitudinal axis and comprising a substantially cylindrical stator core concentric with and extending longitudinally along the longitudinal axis, said stator core comprising a plurality of stator poles, each said stator pole comprising an inner surface spaced radially outward from the longitudinal axis, each said stator pole further comprising a first aperture extending radially outward from said inner surface of the respective stator pole, wherein each said first aperture is angularly offset from a radial line centered on the respective stator pole in a trailing edge direction of the respective stator pole and extends longitudinally along an entire length of said stator core, and wherein at least one said first aperture is in a position relative to the respective radial line on the respective stator pole that is the same as a position of another said first aperture relative to the respective radial line on the respective stator pole; and
a rotor assembly rotatable about the longitudinal axis, said rotor assembly comprising a rotatable shaft and a rotor core concentric with and extending longitudinally along the longitudinal axis, said rotor core comprising a rotor pole comprising an outer surface spaced radially outward from the longitudinal axis, said outer surface spaced radially inward from said inner surfaces of said plurality of stator poles, wherein said rotor core rotates in a rotation direction during operation of said electric machine to generate a magnetic flux and define an inductance curve associated with the electric machine, wherein said rotor pole passes the radial line centered on the respective stator pole prior to passing said first aperture of the respective stator pole when said rotor core rotates in the rotation direction, and wherein the position of each said first aperture provides a detection signal during a negative slope portion of the inductance curve.

2. The electric machine in accordance with claim 1 , wherein each said first aperture extends longitudinally along a portion of said stator core and substantially parallel to the longitudinal axis.

3. The electric machine in accordance with claim 2 , wherein each said first aperture extends longitudinally along an entire length of said stator core.

4. The electric machine in accordance with claim 1 , wherein each said first aperture has a cross-sectional profile shape comprising one or more of rectangular, curved, and polygonal.

5. The electric machine in accordance with claim 1 , wherein said rotor pole further comprises a second aperture extending radially inward from said outer surface of said rotor pole.

6. The electric machine in accordance with claim 5 , wherein said second aperture is angularly offset from a radial line centered on said rotor pole in a trailing edge direction of said rotor pole, wherein said second aperture passes the radial line of one stator pole of the plurality of stator poles prior to passing said first aperture of said one stator pole when said rotor core rotates in the rotation direction.

7. The electric machine in accordance with claim 5 , wherein said second aperture extends longitudinally along a portion of said rotor core and substantially parallel to the longitudinal axis, said second aperture substantially opposite said first aperture.

8. The electric machine in accordance with claim 7 , wherein said second aperture extends longitudinally along an entire length of said rotor core.

9. The electric machine in accordance with claim 5 , wherein said second aperture defines a cross-sectional profile shape comprising one or more of rectangular, curved, and polygonal.

10. The electric machine in accordance with claim 1 , wherein each said first aperture is circumferentially spaced from a leading edge of the respective stator pole in a trailing edge direction of the respective stator pole such that a positive slope portion of the inductance curve is generally smooth, the position of each said first aperture provides an irregularity proximate a maximum inductance point of the inductance curve.

Assignees

• Regal Beloit America Inc

Inventors

• Lobo Nimal Savio
• Yang Hyongyeol
• Ramu Krishnan
• Huff Daniel W
• Lewis John L

Classifications

• Y10T29/49011

  Commutator or slip ring assembly · CPC title

• H02K29/08

  using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) · CPC title

• H02K1/14 Primary

  Stator cores with salient poles · CPC title

• H02K1/246

  Variable reluctance rotors · CPC title

• H02K2213/03

  Machines characterised by numerical values, ranges, mathematical expressions or similar information · CPC title