Controlling fan motors using capacitive sensing

Patent metadata

Field	Value
Publication number	US-9941774-B2
Application number	US-201313962452-A
Country	US
Kind code	B2
Filing date	Aug 8, 2013
Priority date	Aug 8, 2012
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A motor having a rotor, the rotor including a first metal plate having a first size and a second metal plate having a second size arranged on a first surface associated with the rotor. The first metal plate and the second metal plate are arranged adjacent to each other at a predetermined distance from an axis of rotation of the rotor. The first surface rotates perpendicularly about the axis in response to the rotor being rotated about the axis. A stator includes a third metal plate arranged on a second surface associated with the stator. The third metal plate is arranged on the second surface at the predetermined distance from the axis. The second surface is parallel to the first surface and faces the first surface.

First claim

What is claimed is:

1. A motor comprising:
a rotor including (i) a first metal plate having a first size and (ii) a second metal plate having a second size, wherein each of the first metal plate and the second metal plate is arranged on a first surface associated with the rotor,
wherein the first metal plate and the second metal plate are arranged adjacent to each other at a predetermined distance from an axis of rotation of the rotor, and
wherein the first surface rotates along a plane perpendicular to the axis about the axis in response to the rotor being rotated about the axis; and

a stator including a third metal plate arranged on a second surface associated with the stator, wherein the third metal plate is arranged on the second surface at the predetermined distance from the axis, and wherein the second surface is parallel to the first surface and faces the first surface.

2. A system comprising:
the motor of claim 1 ; and
a capacitance sensing module configured to sense, in response to the rotor being rotated, (i) a first capacitance in response to the first metal plate being proximate to the third metal plate and (ii) a second capacitance in response to the second metal plate being proximate to the third metal plate,
wherein the second capacitance is different than the first capacitance.

3. The system of claim 2 , further comprising a direction determination module configured to determine a direction of rotation of the rotor based on the first capacitance and the second capacitance.

4. The system of claim 2 , further comprising a direction determination module configured to determine a direction of rotation of the rotor by comparing a period of revolution of the rotor to a time interval between sensing the first capacitance and the second capacitance during one revolution of the rotor.

5. The system of claim 2 , wherein the capacitance sensing module is configured to sense the first capacitance or the second capacitance at a first time and a second time during two successive revolutions of the rotor, the system further comprising a position determining module configured to determine position of the rotor based on (i) time elapsed from sensing the first capacitance or the second capacitance and (ii) a difference between the first time and the second time.

6. A system comprising:
a motor including
(i) a first metal plate and a second metal plate, wherein each of the first metal plate and the second metal plate is arranged on a first surface associated with a rotor of the motor, and wherein the first surface rotates along a plane perpendicular to an axis of rotation of the rotor about the axis in response to the rotor being rotated about the axis; and
(ii) a third metal plate arranged on a second surface associated with a stator of the motor; and

a capacitance sensing module configured to sense, in response to the rotor being rotated, (i) a first capacitance in response to the first metal plate aligning with the third metal plate and (ii) a second capacitance in response to the second metal plate aligning with the third metal plate.

7. The system of claim 6 , wherein:
the first metal plate has a different size than the second metal plate;
the first, second, and third metal plates are arranged at a predetermined distance from the axis of rotation of the rotor; and
the first surface is parallel to and faces the second surface.

8. The system of claim 6 , further comprising a direction determination module configured to determine a direction of rotation of the rotor based on the first capacitance and the second capacitance.

9. The system of claim 6 , further comprising a direction determination module configured to determine a direction of rotation of the rotor by comparing a period of revolution of the rotor to a time interval between sensing the first capacitance and the second capacitance during one revolution of the rotor.

10. The system of claim 6 , wherein the capacitance sensing module is configured to sense the first capacitance or the second capacitance at a first time and a second time during two successive revolutions of the rotor, the system further comprising a position determining module configured to determine position of the rotor based on (i) time elapsed from sensing the first capacitance or the second capacitance and (ii) a difference between the first time and the second time.

Assignees

• Marvell World Trade Ltd

Inventors

• Sutardja Sehat

Classifications

• G01P13/045

  with speed indication · CPC title

• G01D5/2412

  by varying overlap · CPC title

• G01P3/483

  delivered by variable capacitance detectors · CPC title

• H02K11/21 Primary

  Devices for sensing speed or position, or actuated thereby (specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14) · CPC title

• H02K11/0015 Primary

  Electricity · mapped topic