U.S. patent application number 09/866142 was filed with the patent office on 2001-09-27 for electric motor or generator.
Invention is credited to Caamano, Ramon A..
Application Number | 20010024075 09/866142 |
Document ID | / |
Family ID | 25102797 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010024075 |
Kind Code |
A1 |
Caamano, Ramon A. |
September 27, 2001 |
Electric motor or generator
Abstract
A device such as an electric motor, an electric generator, or a
regenerative electric motor includes a rotor arrangement and a
stator arrangement. The stator arrangement has a dielectric
electromagnet housing and at least one energizable electromagnet
assembly including an overall amorphous metal magnetic core. The
overall amorphous metal magnetic core is made up of a plurality of
individually formed amorphous metal core pieces. The dielectric
electromagnet housing has core piece openings formed into the
electromagnet housing for holding the individually formed amorphous
metal core pieces in positions adjacent to one another so as to
form the overall amorphous metal magnetic core. The device further
includes a control arrangement that is able to variably control the
activation and deactivation of the electromagnet using any
combination of a plurality of activation and deactivation
parameters in order to control the speed, efficiency, torque, and
power of the device.
Inventors: |
Caamano, Ramon A.; (Gilroy,
CA) |
Correspondence
Address: |
BOULDER PATENT SERVICE INC
1021 GAPTER ROAD
BOULDER
CO
803032924
|
Family ID: |
25102797 |
Appl. No.: |
09/866142 |
Filed: |
May 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09866142 |
May 29, 2001 |
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09684766 |
Oct 6, 2000 |
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6259233 |
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09684766 |
Oct 6, 2000 |
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09518800 |
Mar 3, 2000 |
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6154013 |
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09518800 |
Mar 3, 2000 |
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09364969 |
Jul 31, 1999 |
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6049197 |
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09364969 |
Jul 31, 1999 |
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09185297 |
Nov 3, 1998 |
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5986378 |
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09185297 |
Nov 3, 1998 |
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09111249 |
Jul 3, 1998 |
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5903082 |
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09111249 |
Jul 3, 1998 |
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08963290 |
Nov 3, 1997 |
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5814914 |
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08963290 |
Nov 3, 1997 |
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08774946 |
Dec 27, 1996 |
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5731649 |
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Current U.S.
Class: |
290/52 ;
310/254.1; 310/89 |
Current CPC
Class: |
H02K 1/148 20130101;
H02K 21/24 20130101; H02K 1/141 20130101; H02K 21/12 20130101; Y10T
29/49012 20150115; H02K 1/185 20130101; H02K 1/04 20130101; Y02E
10/72 20130101; Y10T 29/49009 20150115; H02K 1/02 20130101; H02K
1/182 20130101; Y02E 10/725 20130101; H02K 29/10 20130101 |
Class at
Publication: |
310/254 ;
310/216; 310/89 |
International
Class: |
H02K 001/12 |
Claims
What is claimed is:
1. A device selected from the group of devices consisting of an
electric motor, an electric generator, and a regenerative electric
motor, the device including a rotor arrangement, at least one
stator arrangement, and a device housing for supporting the rotor
arrangement and the stator arrangement in predetermined positions
relative to one another and for supporting the rotor arrangement
for rotation along a predetermined rotational path about a given
rotor axis, the stator arrangement comprising: a) at least one
energizable electromagnet assembly including an overall amorphous
metal magnetic core and electric coil array which together define
at least one magnetic pole piece, the overall amorphous metal
magnetic core being made up of a plurality of individually formed
amorphous metal core pieces; and b) a dielectric electromagnet
housing for supporting the electromagnet assembly such that the
magnetic pole pieces are positioned adjacent the rotational path of
the rotor arrangement, the dielectric electromagnet housing having
core piece openings formed into the electromagnet housing for
holding the individually formed amorphous metal core pieces in
positions adjacent to one another so as to form the overall
amorphous metal magnetic core.
2. A device according to claim 1 wherein the rotor arrangement
includes at least one rotor magnet having north and south poles,
the rotor arrangement including means for supporting the rotor
magnet for rotation about a given rotor axis such that at least one
of the magnet's poles is accessible along the predetermined
rotational path about the given rotor axis.
3. A device according to claim 1 wherein any voids in the core
piece openings of the electromagnet housing holding the amorphous
metal core pieces are filled with a dielectric oil.
4. A device according to claim 1 wherein at least some of the
individually formed amorphous metal core pieces are amorphous metal
windings formed from a continuous ribbon of amorphous metal.
5. A device according to claim 4 wherein the continuous ribbon of
amorphous metal has a substantially constant ribbon width.
6. A device according to claim 1 wherein at least some of the
individually formed amorphous metal core pieces are made up of a
stack of individual strips of amorphous metal material cut to form
a desired shape.
7. A device according to claim 4 wherein the amorphous metal core
pieces are oil impregnated.
8. A device according to claim 5 wherein at least two of the
individually formed amorphous metal pieces are cylindrical pieces
forming the two magnetic pole pieces of the electromagnet
assembly.
9. A device according to claim 5 wherein the individually formed
amorphous metal core pieces each has a cross-sectional shape
selected from the group of cross-sectional shapes consisting of a
circle, an oval, an egg shape, a toroidal ring, a triangle having
rounded corners, and a trapezoid having rounded corners.
10. A device according to claim 5 wherein the electromagnet
assembly includes a plurality of pole pieces, wherein each of the
pole pieces of the electromagnet assembly is an individually formed
amorphous metal core piece, and wherein at least one of the
individually formed amorphous metal core pieces is a toroidal ring
forming an electromagnetic yoke magnetically coupling each of the
pole pieces to one another.
11. A device according to claim 10 wherein the toroidal ring
electromagnetic yoke includes an annular surface defined by one
continuous edge of the continuous ribbon of amorphous metal after
the ribbon of amorphous metal has been wound, wherein each of the
pole pieces of the electromagnet assembly has a first end
positioned adjacent the predetermined rotational path of the rotor
magnet, and wherein each of the pole pieces of the electromagnet
assembly has a second end positioned adjacent the annular surface
of the toroidal ring electromagnetic yoke.
12. A device according to claim 4 wherein the electromagnet
assembly of the stator arrangement includes a generally U-shaped
overall amorphous metal magnetic core defining two pole pieces,
wherein the two pole pieces are each individually formed amorphous
metal core pieces, and wherein the overall magnetic core includes
an additional individually formed amorphous metal core piece
forming an electromagnetic yoke magnetically coupling the two pole
pieces to one another such that the core pieces together define the
U-shaped overall core.
13. A device according to claim 4 wherein a) the rotor arrangement
includes supporting means for supporting at least one rotor magnet
such that both the north and the south poles of the rotor magnet
are accessible along different predetermined rotational paths about
the given rotor axis; b) the overall magnetic core is a generally
C-shaped overall amorphous metal magnetic core defining two pole
pieces such that each of the pole pieces is positioned adjacent to
a corresponding one of the different predetermined rotational
paths, c) the two pole pieces are each individually formed
amorphous metal core pieces, and d) additional individually formed
amorphous metal core pieces form an electromagnetic yoke
magnetically coupling the two pole pieces to one another such that
the core pieces together define the C-shaped overall core.
14. A device according to claim 1 wherein a) the rotor arrangement
is a barrel shaped rotor arrangement having an outer
circumferential surface; b) the rotor arrangement includes
supporting means for supporting at least one rotor magnet such that
the magnet extends along the outer circumferential surface of the
rotor arrangement generally parallel with the given rotor axis; and
c) the overall magnetic core is a generally tubular shaped overall
amorphous metal magnetic core having its central longitudinal axis
coinciding with the given rotor axis, the overall core defining at
least two magnetic pole piece such that each of the pole pieces
extends radially inward toward the central axis of the overall
core, the pole pieces each being individually formed amorphous
metal core pieces, the overall core including an individually
formed, tubular shaped, amorphous metal core piece forming an
electromagnetic yoke magnetically coupling the pole pieces to one
another such that all of the individually formed core pieces
together define the generally tubular shaped overall core.
15. A device according to claim 2 wherein the rotor magnet is a
super magnet.
16. A device according to claim 1 wherein the device is a multiple
phase device.
17. A device according to claim 16 wherein the multiple phase
device is made up of a plurality of discrete devices mounted in
line on a common shaft with each of the devices being fixed to one
another such that the respective stator arrangements of the
plurality of devices are held in positions that are rotated a
predetermined angle about the given rotor axis relative to one
another.
18. A device according to claim 1 wherein the electromagnet housing
further includes coolant openings formed into the electromagnet
housing for allowing a coolant fluid to be circulated through the
housing.
19. A device according to claim 1 wherein the electromagnet housing
further includes wiring raceway openings formed into the
electromagnet housing for containing wires which interconnect the
coil array.
20. A device according to claim 1 wherein the device is an
induction motor.
21. A method of making an overall amorphous metal magnetic core for
an electromagnet assembly of a device selected from the group of
devices consisting of an electric motor, an electric generator, and
a regenerative electric motor, the method comprising the steps of:
a) forming a plurality of individually formed amorphous metal core
pieces, each having a desired core piece shape; b) providing a
dielectric magnetic core housing including magnetic core piece
openings that define the desired overall magnetic core shape; and
c) assembling the plurality of individually formed amorphous metal
core pieces into the core piece openings of the dielectric magnetic
core housing such that the dielectric core housing holds the core
pieces adjacent to one another so as to form the desired overall
magnetic core shape.
22. A method according to claim 21 further including the step of
filling any voids in the core piece openings of the magnetic core
housing with a dielectric oil.
23. A method according to claim 21 wherein the step of forming a
plurality of individually formed amorphous metal core pieces having
a desired core piece shape includes the step of forming at least
some of the amorphous metal core pieces by winding a continuous
ribbon of amorphous metal material into a coil having a desired
cross-sectional shape.
24. A method according to claim 23 wherein the step of forming a
plurality of individually formed amorphous metal core pieces having
a desired core piece shape includes the step of oil impregnating
the amorphous metal core pieces.
25. A method according to claim 23 wherein the desired
cross-sectional shape is a shape selected from the group of
cross-sectional shapes consisting of a circle, an oval, an egg
shape, a toroidal ring, a triangle having rounded corners, and a
trapezoid having rounded corners.
26. A method according to claim 23 wherein the continuous ribbon of
amorphous metal material is not cut, etched, or otherwise machined
other than cutting the continuous ribbon of amorphous metal
material to the desired length.
27. A method according to claim 21 wherein the step of forming a
plurality of individually formed amorphous metal core pieces having
a desired core piece shape includes the step of forming at least
some of the individually formed amorphous metal core pieces by
stacking individual strips of amorphous metal material cut to form
a desired shape to form the core piece.
28. An arrangement for controlling the rotational speed,
efficiency, torque, and power of a device selected from the group
of devices consisting of an electric motor, an electric generator,
and a regenerative electric motor, the device including a rotor
supported for rotation along a predetermined rotor path about a
given rotor axis and a stator having a plurality of dynamically
activatable and deactivatable electromagnets including amorphous
metal magnetic cores, the electromagnets being spaced apart from
one another adjacent to the predetermined rotor path such that
movement of a particular point of the rotor from a given point
adjacent one electromagnet to a given point adjacent the next
successive electromagnet defines one duty cycle, the arrangement
comprising: a) a position detector arrangement for determining the
position and rotational speed of the rotor relative to the stator
at any given time in a duty cycle and producing corresponding
signals; and b) a controller responsive to the signals for
controlling the activation and deactivation of the electromagnet of
the stator using predetermined device control settings such that,
for each duty cycle, the controller is able to control any
combination of a plurality of activation and deactivation
parameters in order to control the speed, efficiency, torque, and
power of the device.
29. An arrangement according to claim 28 wherein the activation and
deactivation parameters include (i) the duty cycle activation time
which is the continuous duration of time in which the electromagnet
of the stator is activated for each duty cycle, (ii) the start/stop
points of the duty cycle activation time which is the time at which
the duty cycle activation time starts and stops during the duty
cycle relative to the rotational position of the rotor, and (iii)
the modulation of the duty cycle activation time which is the pulse
width modulating of the electromagnet by activating and
deactivating the electromagnet during what would otherwise be the
continuous duty cycle activation time.
30. An arrangement according to claim 28 wherein the position
detector arrangement includes an encoder disk supported for
rotation with the rotor and also includes an array of optical
sensors arranged in close proximity to the encoder disk, the
encoder disk having a plurality of concentric tracks with spaced
apart position indicating openings formed into each of the tracks,
each of the optical sensors corresponding to an associated one of
the concentric tracks and the optical sensors being positioned
adjacent to its associated concentric track such that the sensor is
able to detect the presence of the position indicating openings
formed into its associated concentric track so as to be able to
detect the position of the rotor relative to the stator.
31. An arrangement according to claim 30 wherein the controller
includes means for using the rate at which encoder disk of the
position detector arrangement detects changes in the position of
the rotor relative to the stator to determine the rotational speed
of the rotor relative to the stator when the rotor is rotating.
32. An arrangement according to claim 31 wherein the controller
further includes a counter arrangement capable of counting in
increments of time which allow each duty cycle to be divided into a
multiplicity of time periods which the controller uses to control
when to activate and deactivate the electromagnet.
33. An arrangement according to claim 28 wherein the rotor includes
at least one permanent super magnet.
34. A method for controlling the rotational speed, efficiency,
torque, and power of a device selected from the group of devices
consisting of an electric motor, an electric generator, and a
regenerative electric motor, the device including a rotor supported
for rotation along a predetermined rotor path about a given rotor
axis and a stator having a plurality of dynamically activatable and
deactivatable electromagnets including amorphous metal magnetic
cores, the electromagnets being spaced apart from one another
adjacent to the predetermined rotor path such that movement of a
particular point of the rotor from a given point adjacent one
electromagnet to a given point adjacent the next successive
electromagnet defines one duty cycle, the method comprising the
steps of: a) determining the position and rotational speed of the
rotor relative to the stator at any given time in the duty cycle
and producing corresponding signals; and b) using the signals to
select and use predetermined device control settings to control the
activation and deactivation of the electromagnet of the stator such
that for each duty cycle, the controller is able to control any
combination of a plurality of activation and deactivation
parameters in order to control the speed, efficiency, torque, and
power of the device.
35. A method according to claim 34 wherein the activation and
deactivation parameters include (i) the duty cycle activation time
which is the continuous duration of time in which the electromagnet
of the stator is activated for each duty cycle, (ii) the start/stop
points of the duty cycle activation time which is the timing at
which the duty cycle activation time starts and stops during the
duty cycle relative to the rotational position of the rotor, and
(iii) the modulation of the duty cycle activation time which is the
pulse width modulating of the electromagnet by activating and
deactivating the electromagnet during what would otherwise be the
continuous duty cycle activation time.
36. A method according to claim 34 wherein the step of determining
the position of the rotor includes the step of using an encoder
disk supported for rotation with the rotor and an array of optical
sensors arranged in close proximity to the encoder disk to detect
the position of the rotor.
37. A method according to claim 36 wherein the encoder disk has a
plurality of concentric tracks with position indicating openings
formed into each of the tracks and wherein each of the optical
sensors is positioned adjacent to an associated one of the
concentric tracks such that the optical sensors detect the presence
of the position indicating openings formed into its associated
concentric track so as to allow the sensors to detect the position
of the rotor relative to the stator.
38. A method according to claim 37 wherein the step of controlling
the activation and deactivation of the electromagnet includes the
step of using rate at which the encoder disk detects changes in the
position of the rotor relative to the stator to determine the
rotational speed of the rotor relative to the stator when the rotor
is rotating.
39. A method according to claim 38 wherein the step of controlling
the activation and deactivation of the electromagnet includes the
step of using the combination of (i) the rotational speed of the
rotor and (ii) a counter arrangement capable of counting in
increments of time which allow each duty cycle to be divided into a
multiplicity of time periods to control when to activate and
deactivate the electromagnet.
40. A method according to claim 34 wherein the rotor includes at
least one permanent super magnet.
41. A device for generating electricity comprising the combination
of: a) a gas turbine engine; and b) a generator directly driven by
the gas turbine engine without reduction gears or other means for
reducing the rotational speed at which the turbine engine drives
the generator, the generator including a rotor arrangement with at
least one rotor super magnet and a stator arrangement with at least
one dynamically activatable and deactivatable electromagnet
assembly including an amorphous metal magnetic core.
42. A method of generating electricity, the method comprising the
steps of: a) providing a gas turbine engine; and b) directly
driving a generator using the gas turbine engine without using
reduction gears or other means for reducing the rotational speed at
which the turbine engine drives the generator, the generator
including a rotor arrangement with at least one rotor super magnet
and a stator arrangement with at least one dynamically activatable
and deactivatable electromagnet assembly including an amorphous
metal magnetic core.
43. A method of conditioning the electrical output of an electric
generator driven by a input drive device, the generator including a
stator assembly having at least one dynamically activatable and
deactivatable stator coil and a rotor assembly, the method
comprising the steps of: a) determining the position and rotational
speed of the rotor assembly relative to the stator assembly at any
given time and producing corresponding signals; and b) using the
signals, variably controlling the activation and deactivation of
the stator coil such that the electrical output of the generator is
conditioned to a desired electrical output without requiring the
use of additional electrical power conditioning devices.
44. A method according to claim 43 wherein the input drive device
is a wind mill.
45. A method according to claim 43 further including the step of
using a portion of the electrical power generated by the generator
to drive the generator as an electric motor.
46. A method according to claim 45 wherein the generator is driven
as an electric motor in a way which reduces the amount of
resistance the generator places on the input drive device.
47. A method according to claim 45 wherein the generator is driven
as an electric motor in a way which increases the amount of
resistance the generator places on the input drive device.
48. An arrangement for use in an electric generator for
conditioning the electrical output of the electric generator, the
generator being driven by a input drive device, the generator
including a stator assembly having at least one dynamically
activatable and deactivatable stator coil and a rotor assembly, the
arrangement comprising: a) a position detector arrangement for
determining the position and rotational speed of the rotor assembly
relative to the stator assembly at any given time and producing
corresponding signals; and b) a controller responsive to the
signals for variably controlling the activation and deactivation of
the stator coil such that the electrical output of the generator is
conditioned to a desired electrical output without requiring the
use of additional electrical power conditioning devices.
49. An arrangement according to claim 48 wherein the input drive
device is a wind mill.
50. An arrangement according to claim 49 wherein the controller
uses a portion of the electrical power generated by the generator
to drive the generator as an electric motor.
51. An arrangement according to claim 50 wherein the controller
drives the generator as an electric motor in a way which reduces
the amount of resistance the generator places on the input drive
device.
52. An arrangement according to claim 50 wherein the generator is
driven as an electric motor in a way which increases the amount of
resistance the generator places on the input drive device.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to electric motors,
generators, and regenerative motors. The term regenerative motor is
used herein to refer to a device that may be operated as either an
electric motor or a generator. More specifically, the invention
relates to an electric motor, generator, or regenerative motor
including a stator arrangement which itself includes an
electromagnet assembly having an amorphous metal magnetic core made
up of a plurality of individually formed amorphous metal core
pieces. The present invention also provides a control arrangement
that is able to variably control the activation and deactivation of
an electromagnet using any combination of a plurality of activation
and deactivation parameters in order to control the speed,
efficiency, power, and torque of the device.
[0002] The electric motor and generator industry is continuously
searching for ways to provide motors and generators with increased
efficiency and power density. For some time now, it has been
believed that motors and generators constructed using permanent
super magnet rotors (for example cobalt rare earth magnets and
Neodymium-Iron-Boron magnets) and stators including electromagnets
with amorphous metal magnetic cores have the potential to provide
substantially higher efficiencies and power densities compared to
conventional motors and generators. Also, because amorphous metal
cores are able to respond to changes in a magnetic field much more
quickly than conventional ferrous core materials, amorphous metal
magnetic cores have the potential to allow much faster field
switching within motors and generators, and therefore allow much
higher speed and better controlled motors and generators than
conventional ferrous cores. However, to date it has proved very
difficult to provide an easily manufacturable motor or generator
which includes amorphous metal magnetic cores.
[0003] Amorphous metal is typically supplied in a thin continuous
ribbon having a uniform ribbon width. However, amorphous metal is a
very hard material making it very difficult to cut or form easily,
and once annealed to achieve peak magnetic properties, becomes very
brittle. This makes it difficult and expensive to use the
conventional approach to constructing a magnetic core. This
conventional approach typically involves cutting individual core
layers having a desired shape from a sheet of core material and
laminating the layers together to form a desired overall magnetic
core shape. The brittleness of amorphous metal also causes concern
for the durability of a motor or generator which utilizes amorphous
metal magnetic cores. Magnetic cores are subject to extremely high
magnetic forces which change at very high frequencies. These
magnetic forces are capable of placing considerable stresses on the
core material which may damage an amorphous metal magnetic
core.
[0004] Another problem with amorphous metal magnetic cores is that
the magnetic permeability of amorphous metal material is reduced
when it is subjected to physical stresses. This reduced
permeability may be considerable depending upon the intensity of
the stresses on the amorphous metal material. As an amorphous metal
magnetic core is subjected to stresses, the efficiency at which the
core directs or focuses magnetic flux is reduced resulting in
higher magnetic losses, reduced efficiency, increased heat
production, and reduced power. This phenomenon is referred to as
magnetostriction and may be caused by stresses resulting from
magnetic forces during the operation of the motor or generator,
mechanical stresses resulting from mechanical clamping or otherwise
fixing the magnetic core in place, or internal stresses caused by
the thermal expansion and/or expansion due to magnetic saturation
of the amorphous metal material.
[0005] Conventional magnetic cores are formed by laminating
successive layers of core material together to form the overall
core. However, as mentioned above, amorphous metal is difficult to
cut or form easily. Therefore, in the past, amorphous metal cores
have often been formed by rolling an amorphous metal ribbon into a
coil with each successive layer of the material being laminated to
the previous layer using an adhesive such as an epoxy. When in use
in an electric motor or generator, this laminated construction
restricts the thermal and magnetic saturation expansion of the coil
of amorphous metal material and results in high internal stresses.
These stresses cause magnetostriction that reduces the efficiency
of the motor or generator as described above. Also, this
construction places a layer of adhesive between each coil of the
core. Since amorphous metal material is typically provided as a
very thin ribbon, for example only a couple of mils thick, a
significant percentage of the volume of the core ends up being
adhesive material. This volume of adhesive reduces the overall
density of the amorphous metal material within the laminated core,
and therefore, undesirably reduces the efficiency of the core to
focus or direct the magnetic flux for a given volume of overall
core material.
[0006] The present invention provides a method and arrangement for
minimizing the stresses on an amorphous metal magnetic core in an
electric motor, generator, or regenerative motor. This method and
arrangement eliminates the need for laminating the various layers
of the amorphous metal thereby reducing the internal stresses on
the material and increasing the density of the amorphous material
within the overall core. Also, in order to take advantage of the
high speed switching capabilities of the amorphous metal magnetic
core material, the present invention provides control methods and
arrangements that are able to variably control the activation and
deactivation of the electromagnet of an electric motor, generator,
or regenerative motor device including an amorphous metal magnetic
core by using a combination of a plurality of different activation
and deactivation parameters in order to control the speed,
efficiency, torque, and power of the device.
SUMMARY OF THE INVENTION
[0007] As will be described in more detail hereinafter, a device
such as an electric motor, an electric generator, or a regenerative
electric motor is disclosed herein. The device includes a rotor
arrangement, at least one stator arrangement, and a device housing
for supporting the rotor arrangement and the stator arrangement in
the predetermined positions relative to one another. The device
housing also supports the rotor arrangement for rotation along a
predetermined rotational path about a given rotor axis. The stator
arrangement has at least one energizable electromagnet assembly
including an overall amorphous metal magnetic core and an electric
coil array which together define at least one magnetic pole piece.
The overall amorphous metal magnetic core is made up of a plurality
of individually formed amorphous metal core pieces. The stator
arrangement also includes a dielectric electromagnet housing for
supporting the electromagnet assembly such that the magnetic pole
pieces are positioned adjacent the rotational path of the rotor
arrangement. The dielectric electromagnet housing has core piece
openings formed into the electromagnet housing for holding the
individually formed amorphous metal core pieces in positions
adjacent to one another so as to form the overall amorphous metal
magnetic core.
[0008] In one preferred embodiment, the rotor arrangement has at
least one rotor magnet with north and south poles and the rotor
arrangement has an arrangement for supporting the rotor magnet for
rotation about a given rotor axis such that at least one of the
magnet's poles is accessible along a predetermined rotational path
about the given rotor axis. In a preferred embodiment, the rotor
magnet is a super magnet.
[0009] In some embodiments, the individually formed amorphous metal
core pieces are amorphous metal windings formed from a continuous
ribbon of amorphous metal. Preferably, the continuous ribbon of
amorphous metal has a substantially constant ribbon width. The
individually formed amorphous metal core pieces may have a variety
of cross-sectional shapes including a circle, an oval, an egg
shape, a toroidal ring, a triangle having rounded corners, and a
trapezoid having rounded corners. Alternatively, the individually
formed amorphous metal core pieces may be formed from individual
strips of amorphous metal material stacked in an associated core
piece opening of a core piece housing. Also, in some embodiments,
any voids in the core piece openings of the electromagnet housing
holding the amorphous metal core pieces are filled with a
dielectric oil. Additionally, the amorphous metal core pieces may
be oil impregnated.
[0010] In one embodiment, the stator arrangement includes a
plurality of electromagnet assemblies, each having a plurality of
pole pieces. Each of the pole pieces is an individually formed
amorphous metal core piece. Furthermore, at least one of the
individually formed amorphous metal core pieces is a toroidal ring
forming an electromagnetic yoke magnetically coupling each of the
pole pieces to one another. The toroidal ring electromagnetic yoke
includes an annular or other such continuous surface defined by one
continuous edge of the continuous ribbon of amorphous metal after
the ribbon of amorphous metal has been wound about itself. Each of
the pole pieces of the electromagnet assembly has a first end
(defined by one continuous edge of the ribbon) positioned adjacent
the predetermined rotational path of the rotor magnet. Also, each
of the pole pieces of the electromagnet assembly has a second end
(defined by the other continuous edge of the ribbon) positioned
adjacent the annular surface of the toroidal ring electromagnetic
yoke.
[0011] In another embodiment, the electromagnet of the stator
arrangement includes a generally U-shaped overall amorphous metal
magnetic core having two pole pieces. The two pole pieces are each
individually formed amorphous metal core pieces. An additional
individually formed amorphous metal core piece forms an
electromagnetic yoke magnetically coupling the two pole pieces to
one another such that the core pieces together define the U-shaped
overall core.
[0012] In still another embodiment, the arrangement supporting the
rotor magnet supports the rotor magnet such that both the north and
the south poles of the rotor magnet are accessible along different
predetermined rotational paths about the given rotor axis. The
electromagnet of the stator arrangement includes a generally
C-shaped overall amorphous metal magnetic core having two pole
pieces with each of the pole pieces positioned adjacent to a
corresponding one of the predetermined rotational paths of the
north and south poles of the rotor magnet. The overall magnetic
core of the electromagnet assembly is a generally C-shaped overall
amorphous metal magnetic core defining the two pole pieces such
that each of the pole pieces is positioned adjacent to a
corresponding one of the different predetermined rotational paths.
The two pole pieces are each individually formed amorphous metal
core pieces. Additional individually formed amorphous metal core
pieces form an electromagnetic yoke magnetically coupling the two
pole pieces to one another such that the core pieces together
define the C-shaped overall core.
[0013] A method of making an amorphous metal magnetic core for an
electromagnet of a device such as an electric motor, an electric
generator, or a regenerative electric motor is also disclosed
herein. The method includes the step of forming a plurality of
individually formed amorphous metal core pieces, each having a
desired core piece shape. A dielectric magnetic core housing
including magnetic core piece openings that define the desired
overall magnetic core shape is provided. The plurality of
individually formed amorphous metal core pieces are assembled into
the core piece openings of the dielectric magnetic core housing
such that the dielectric core housing holds the core pieces
adjacent to one another so as to form the desired overall magnetic
core shape. In a preferred method, each core piece is wound into
its final shape from a continuous ribbon of amorphous metal.
[0014] In accordance with another aspect of the present invention,
a method and arrangement for controlling the rotational speed and
input/output power and torque of a device such as an electric
motor, an electric generator, or a regenerative electric motor is
disclosed herein. The device includes a rotor supported for
rotation along a predetermined rotor path about a given rotor axis.
Preferably, the rotor includes at least one permanent super magnet.
The device also includes a stator having a plurality of dynamically
activatable and deactivatable electromagnet assemblies (also
referred to herein merely as electromagnets) with amorphous metal
magnetic cores. The electromagnets are spaced apart from one
another adjacent to the predetermined rotor path such that movement
of a particular point on the rotor (rotor point) from a given point
adjacent one electromagnet (stator point) to a given point adjacent
the next successive electromagnet (stator point) defines one duty
cycle. A position detector arrangement determines the position and
rotational speed of the rotor relative to the stator at any given
time in a duty cycle and produces corresponding signals. A
controller responsive to the signals controls the activation and
deactivation of the electromagnets of the stator using
predetermined device control settings such that, for each duty
cycle, the controller is able to control any combination of a
plurality of activation and deactivation parameters in order to
control the speed, efficiency, and input/output power and torque of
the device.
[0015] In a preferred embodiment, the activation and deactivation
parameters include (i) the duty cycle activation time which is the
continuous duration of time in which the electromagnet of the
stator is activated (with either one polarity or the other) for
each duty cycle, (ii) the start/stop points of the duty cycle
activation time which are the times at which the duty cycle
activation time starts and stops during the duty cycle relative to
the rotational position of the rotor as it moves through the duty
cycle from stator point to the next adjacent stator point, and
(iii) the modulation of the duty cycle activation time which is the
pulse width modulating of the electromagnet by activating and
deactivating the electromagnet during what would otherwise be the
continuous duty cycle activation time.
[0016] In another embodiment, the position detector arrangement
includes an encoder disk supported for rotation with the rotor and
also includes an array of optical sensors arranged in close
proximity to the encoder disk. The encoder disk has a plurality of
concentric tracks with spaced apart position indicating openings
which are actually through-holes in the disk. Each of the optical
sensors corresponds to and is optically aligned with an associated
one of the concentric tracks such that each sensor is able to
detect the presence of the position indicating openings defining
its associated concentric track so as to be able to detect the
position of the rotor relative to the stator. Preferably these
openings are sized and positioned to represent a digital byte of
rotor positional information with each track contributing one bit
of the overall digital byte. In this way, during startup of the
motor/generator device, the position of the rotor can be precisely
determined.
[0017] In still another embodiment, the controller further includes
a counter arrangement capable of counting in increments of time
which allow each duty cycle to be divided into a multiplicity of
time periods which the controller uses to control when to activate
and deactivate the electromagnet.
[0018] In accordance with another aspect of the present invention,
a method and arrangement for conditioning the electrical output of
an electric generator driven by a input drive device is disclosed.
The generator includes a stator assembly having at least one
dynamically activatable and deactivatable stator coil and a rotor
assembly. A position detector arrangement determines the position
and rotational speed of the rotor assembly relative to the stator
assembly at any given time and produces corresponding signals. A
controller responsive to the signals variably controls the
activation and deactivation of the stator coil such that the
electrical output of the generator is conditioned to a desired
electrical output without requiring the use of additional
electrical power conditioning devices. In one embodiment, the input
drive device is a wind mill. Furthermore, the controller may use a
portion of the electrical power generated by the generator to drive
the generator as an electric motor. The generator may be driven as
an electric motor in a way which reduces the amount of resistance
the generator places on the input drive device or in a way which
increases the amount of resistance the generator places on the
input drive device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The features of the present invention may best be understood
by reference to the following description of the presently
preferred embodiments together with the accompanying drawings in
which:
[0020] FIG. 1 is a diagrammatic cross-sectional view of a device
designed in accordance with the present invention including a rotor
arrangement, a stator arrangement having a stator housing and an
overall amorphous metal magnetic core made up of individually
formed amorphous metal core pieces, and a control arrangement
having an encoder disk.
[0021] FIG. 2 is a diagrammatic plan view of the rotor arrangement
of the device of FIG. 1.
[0022] FIG. 3A is an orthographic diagrammatic view of one
embodiment of an overall amorphous metal magnetic core forming part
of the stator arrangement of the device of FIG. 1.
[0023] FIG. 3B is a diagrammatic cross-sectional view of the stator
housing of FIG. 1.
[0024] FIG. 4 is a diagrammatic plan view of the encoder disk of
the device of FIG. 1.
[0025] FIG. 5 is a graph illustrating various activation and
deactivation parameters which the control arrangement of the device
of FIG. 1 may use to control the device of FIG. 1.
[0026] FIG. 6 is a diagrammatic view of one embodiment of the
invention in which a windmill drives a generator designed in
accordance with the invention.
[0027] FIG. 7 is a diagrammatic view of another embodiment of the
invention in which a turbine engine drives a generator designed in
accordance with the invention.
[0028] FIG. 8 is a perspective view of a second embodiment of an
overall amorphous metal magnetic core designed in accordance with
the present invention.
[0029] FIG. 9 is a perspective view of a third embodiment of an
overall amorphous metal magnetic core designed in accordance with
the present invention.
[0030] FIG. 10 is a perspective view of a fourth embodiment of an
overall amorphous metal magnetic core designed in accordance with
the present invention.
[0031] FIGS. 11A-H are diagrammatic perspective views of various
embodiments of the individual amorphous metal core pieces having
various cross-sectional shapes.
[0032] FIG. 12 is a diagrammatic cross-sectional view of a
multiphase device designed in accordance with the present
invention.
[0033] FIG. 13 is a diagrammatic plan view of a stator arrangement
of another embodiment of a multiphase device designed in accordance
with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] Turning to the drawings, wherein like components are
designated by like reference numerals throughout the various
figures, attention is initially directed to FIGS. 1-3B. FIG. 1
illustrates a cross sectional view of a device 10 designed in
accordance with the present. Although device 10 will be referred to
as an electric motor or an electric generator at various times
throughout this description, it should be understood that device 10
may take the form of a motor, a generator, an alternator, or a
regenerative motor depending on the requirements of the application
in which the device is used. For purposes of this description, the
term regenerative motor refers to a device that may be operated as
either an electric motor or an electric generator. Also, although
device 10 will in most cases be described as a DC brushless motor,
it should be understood that it may take the form of a wide variety
of other types of motors and/or generators and still remain within
the scope of the invention. These other types of motors and/or
alternators/generators include, but are not limited to, DC
synchronous devices, variable reluctance or switched reluctance
devices, and induction type motors.
[0035] As best shown in FIG. 1, device 10 includes a shaft 14, a
rotor arrangement 16, a stator arrangement 18, and a device housing
20. Device housing 20 supports shaft 14 for rotation about the
longitudinal axis of the shaft using bearings 22 or any other
suitable and readily providable arrangement for supporting a shaft
for rotation. Rotor arrangement 16 is fixed to shaft 14 for
rotation with the shaft about the longitudinal rotational axis of
shaft 14. Stator arrangement 18 is supported by device housing 20
such that the stator arrangement is positioned adjacent the
rotational path of the rotor arrangement.
[0036] Referring now to FIG. 2, which is a plan view of one
preferred embodiment of rotor arrangement 16, rotor arrangement 16
will be described in more detail. In this embodiment, rotor
arrangement 16 is a disk or axial type rotor including six radially
spaced apart permanent super magnets 24a-f (for example cobalt rare
earth magnets), each having opposite ends defining north and south
poles. Magnets 24a-f are supported for rotation about the axis of
shaft 14 by a rotor disk 26 or any other suitable arrangement such
that the magnetic poles of magnets 24a-f are accessible along two
predetermined rotational paths about the shaft axis and adjacent
the rotor arrangement. They are oriented relative to one another
such that on each side of the rotor disk, the magnets present
alternating north and south poles as shown in FIG. 2.
[0037] Although magnets 24a-f have been described as being
permanent super magnets, this is not a requirement. Alternatively,
the magnets may be other magnetic materials, or, in some cases may
be electromagnets. Also, although the rotor arrangement has been
described as being a disk or axial type rotor, this is not a
requirement. Instead, the rotor may take on a wide variety of
specific configurations such as a barrel or radial type rotor with
the magnets being positioned on the outer circumference of the
barrel or radial type rotor. Although the rotor has been described
as including six magnets, it should be understood that the rotor
may include any number of magnets and still remain within the scope
of the invention. And finally, although the rotor arrangement has
been described as including magnets, this is not a requirement. For
example, in the case of an induction motor, rotor arrangement 16
would not include magnets 24a-g. Instead, as would be understood by
those skilled in the art, rotor disk 26 would be constructed from
an iron based material or some other magnetic material to form a
magnetic rotor core which is driven by a rotating magnetic field
created by the switching of the stator arrangement.
[0038] As best shown in FIG. 1, in the embodiment being described,
stator arrangement 18 includes two stator housings 28a and 28b with
the stator housings being positioned adjacent opposite sides of
rotor arrangement 16. Stator housings 28a and 28b are mirror images
of one another, and therefore, only stator housing 28a will be
described in detail. Stator housing 28a is formed from a dielectric
material such as, but not limited to, a high strength composite or
plastic material. Any appropriate material may be used to form the
stator housing so long as it is dielectric and able to properly
support all of the associated components making up stator
arrangement 18.
[0039] In accordance with the present invention, stator housing 28a
has a plurality of openings including core piece openings 30 and
coil openings 32 formed into the housing for supporting a
dynamically activatable and deactivatable electromagnet assembly
34. The electromagnet assembly 34 includes an overall amorphous
metal magnetic core 36 and a coil array 38. Coil array 38 is
supported in coil openings 32. Also in accordance with the
invention, overall amorphous metal core 36 is made up of a
plurality of individually formed amorphous metal core pieces 36a-g
some of which form magnetic pole pieces as best shown in FIG. 3A.
Stator housing 28a supports electromagnet assembly 34 such that the
pole pieces of the electromagnet assembly are held adjacent to one
of the predetermined rotational paths of the magnetic poles of
magnets 24a-f on rotor arrangement 16 as best shown in FIG. 2.
[0040] FIG. 3A illustrates the specific configuration of overall
amorphous metal core 36 for the particular embodiment shown in FIG.
1. Each individual core piece 36a-g is formed by winding a
continuous ribbon of amorphous metal material into the desired
shape. In the case of core pieces 36a-f, the core piece shape is a
generally cylindrical shape such that the opposing continuous edges
of each of these core pieces define opposite ends 37a and 37b of
the core piece. However, in the case of core piece 36g, the core
piece shape is a toroidal ring having an annular surface 40 defined
by one continuous edge of the continuous amorphous metal ribbon
wound to form toroidal ring core piece 36g. In either case, for
this embodiment, the continuous amorphous metal ribbon is not cut,
etched, or otherwise machined other than initially cutting the
continuous ribbon of amorphous metal to the desired length required
to form the desired core piece shape. Each of the cylindrical
shaped core pieces 36a-f forms a pole piece of overall core 36 with
one end 37a of each cylindrical core piece being positioned against
annular surface 40 of toroidal ring shaped core piece 36g, and the
other end 37b projecting out away from annular surface 40. Toroidal
ring core piece 36g acts as a magnetic yoke preventing leakage of
magnetic flux and magnetically coupling each of the cylindrical
core pieces 36a-f.
[0041] FIG. 3B illustrates stator housing 28a apart from, but
designed to contain, core 36 of FIG. 3A. Note specifically the
various core piece openings 30 and coil openings 32. Stator housing
28a also includes coolant openings 39 and wire raceway openings 41.
Using coolant openings 39, a coolant fluid may be circulated
through stator housing 28a to prevent excessive heat buildup in
stator housing 28a, coil array 38, and core 36. Coolant openings
may be formed in any appropriate location within the stator housing
in order to provide cooling for the device. Wire raceway openings
41 are used to run wires which interconnect coil array 38. Although
FIG. 3B illustrates one specific configuration of the stator
housing which is designed to house the core pieces illustrated in
FIG. 3A, it should be understood that the stator housing may take
on a wide variety of configurations which vary depending on the
specific core design.
[0042] As best shown in FIGS. 1, 3A, and 3B, individually formed
core pieces 36a-g are supported within core piece openings 30 of
stator housing 28a such that they are held in their respective
positions relative to one another. Because core piece openings 30
are formed in stator housing 28a to have the proper shape for
supporting each of the various individually formed core pieces
36a-f, core pieces 36a-f may be formed by winding the amorphous
metal ribbon material without laminating the layers of the winding.
This allows each individually formed core piece to thermally expand
and/or expand due to magnetic saturation, causing the winding to
slightly uncoil, without causing internal stress within the overall
core or within any of the individually formed core pieces. This
arrangement substantially reduces the problems caused by
magnetostriction described in the background of the invention.
Also, this arrangement eliminates the need to laminate the core
pieces and therefore eliminates the volume of space within the
overall core which is taken up by the laminating material. Because
of this, a greater amount of amorphous metal material is able to be
placed into a given volume which improves the efficiency at which a
magnetic core is able to direct or focus magnetic flux. At the same
time, each stator housing holds the pole pieces 36a-f in direct
contact with yoke 36g so that the entire core, from a functional
standpoint, approximates a single integrally formed core. Stator
housing 28a may also completely encase overall amorphous metal core
36 creating a sealed enclosure which prevents corrosion of the core
pieces.
[0043] In the embodiment shown in FIG. 1, any voids in core piece
openings 30 that are not filled by core pieces 36a-g are filled
with a dielectric oil 42 and core piece openings 30 are sealed to
maintain the oil within the voids. This oil filling of the core
piece openings acts as a cushion to help prevent damage to the
amorphous metal material as it is subjected to the large and
varying magnetic forces associated with the motor. This oil filling
also helps to thermally equalize the stator arrangements and may be
used to improve the heat dissipating characteristics of the overall
device. Also, amorphous metal core pieces 36a-g are oil
impregnated. This allows the windings of the amorphous metal core
pieces to more easily expand due to magnetic saturation and thermal
expansion of the amorphous metal material further reducing stresses
that may cause magnetostriction. Although, the core piece openings
described above are oil filled and the core pieces are oil
impregnated, this is not a requirement. The invention would equally
apply to devices which use magnetic cores made up of individually
formed amorphous metal magnetic core pieces supported in openings
of a housing to form an overall amorphous metal magnetic core shape
regardless of whether or not the openings were filled with oil and
the core pieces were oil impregnated.
[0044] Device 10 is a brushless, synchronous device in which the
coils making up electromagnet coil array 38 within stator housing
28a are all electrically connected such that they are activated and
deactivated at the same time. In the embodiment shown in FIG. 1,
coil array 38 includes six pole piece coils, two of which are
illustrated in FIG. 1 as coils 38a and 38d. Coil array 38 may be
epoxied or otherwise fixed into position in order to add to the
overall structural integrity of the stator arrangement. Each coil
is positioned around a corresponding one of core pieces 36a-f, two
of which are illustrated in FIG. 1 as core pieces 36a and 36d. Coil
array 38 is wound such that the projecting ends of the pole pieces
formed by magnetic core pieces 36a-f form alternating north and
south poles when coil array 38 is activated. Toroidal ring core
piece 36g acts as a magnetic yoke redirecting the magnetic flux
associated with the ends of core pieces 36a-f that are adjacent to
toroidal ring core piece 36g to the adjacent pole pieces of the
opposite polarity. When the device is operated as an electric
motor, switching the direction of current flow through coil array
38 reverses the polarity of each of the pole pieces of
electromagnet assembly 34. As will be described in more detail
hereinafter, in the case of a generator, switching the way in which
the electromagnets are connected to a load controls the power
output and the condition of the electricity produced by the
generator. This arrangement allows the alternating north and south
poles of electromagnet assembly 34 of stator arrangement 18 to
controllably interact with the alternating north and south poles of
permanent magnets 24a-f of rotor arrangement 16.
[0045] Device 10 also includes a control arrangement 44 for
activating and deactivating coil array 38 with alternating
polarity. Control arrangement 44 includes a controller 46 which may
be any suitable and readily providable controller that is capable
of dynamically activating and deactivating electromagnet assembly
34 with varying polarity. Preferably, controller 46 is a
programmable controller capable of activating and deactivating
electromagnet assembly 34 at a rate of speed much higher than is
typically done in conventional electric motors and generators.
Because of the inherent speed at which the magnetic field may be
switched in an amorphous metal core, for each duty cycle of the
device, the stator arrangement of device 10 allows controller 46 to
use any combination of a plurality of activation and deactivation
parameters to control the rotational speed, power, and torque
output of device 10. For purposes of this description, one duty
cycle is defined as the movement of a particular point of the rotor
from a given stator point adjacent one electromagnet pole piece of
the stator arrangement to a given stator point adjacent the next
successive electromagnet pole piece of the stator arrangement, as
mentioned previously.
[0046] Still referring to FIG. 1, control arrangement 44 also
includes a position detector arrangement 48 for determining the
position and rotational speed of rotor arrangement 16 relative to
stator arrangement 18 at any given time for each duty cycle and for
producing corresponding signals. Detector arrangement 48 includes
an encoder disk 50 supported on shaft 14 for rotation with rotor
arrangement 16. Detector arrangement 48 also includes an array of
optical sensors 52 positioned adjacent the encoder disk.
[0047] As illustrated in FIG. 4, which is a plan view of encoder
disk 50, encoder disk 50 includes a plurality of concentric tracks
54 with position indicating openings 56 formed into each of the
tracks. In this embodiment, disk 50 includes six concentric tracks
54a-f. Disk 50 is divided into three one hundred and twenty degree
arc, pie shaped sections 58, each of which are identical to one
another. Each section 58 is associated with a pie shaped section of
the rotor arrangement extending from a given point on a first rotor
magnet having a particular polarity to a corresponding point on the
next successive magnet having the same polarity (i.e. from one
south pole past a north pole to the next south pole). Inner track
54a has one long opening 56a extending half (a sixty degree arc) of
the length of track 54a in each section 58. In this case, each of
these openings corresponds to one duty cycle of the device and the
three openings together are aligned with every other one of the six
rotor magnets (i.e. the three magnets having the same polarity on
each given side of the rotor disk). Within each section, each
successive track has twice as many openings which are half as long
as the openings in the previous track. That is track 54b has two
openings 56b within each section, track 54c has four openings 56c
and so on with the outside track having thirty two openings, each
having an arc of one and seven eighths of a degree.
[0048] Optical sensor array 52 includes six optical sensors with
each sensor corresponding to and positioned in optical alignment
with one of the concentric tracks on encoder disk 50. Array 52 is
positioned adjacent encoder disk 50 such that optical sensors
detect the presence of openings 56. With each of the optical
sensors providing one bit of information, array 52 is able to
provide controller 46 with a binary word (a byte) which identifies
the position of the rotor arrangement within less than a two degree
arc. Using the most significant bit, that is the sensor associated
with track 54a, controller 46 is also able to determine the
location of the alternating north and south poles of the magnets
since the openings 56a of track 54a corresponds to every other
magnet on the rotor disk as described above.
[0049] Controller 46 also includes a counter arrangement 49 capable
of counting in increments of time which allow each duty cycle
(sixty degree arc) to be divided into a multiplicity of time
periods or counts, for example, 1600 counts per duty cycle when the
device is rotating at a predetermined maximum speed. This
corresponds to one hundred counts for each opening 56f, or, in
other words, one hundred times the resolution provided by the
encoder disk. For illustrative purposes, for a high speed motor
capable of operating at 20,000 RPM, this would require a counter
arrangement or clock capable of operating at 3.2 million counts per
second or a 3.2 MHz clock. Although only one specific clock speed
has been described in detail, it should be understood that the
present invention would equally apply regardless of the specific
clock speed of the counter arrangement.
[0050] Controller 46 is arranged to be able to activate or
deactivate electromagnet assembly 34 at any predetermined count of
counter arrangement 49. This provides extremely precise control of
the activation and deactivation of the electromagnets. Although the
example of an operating speed of 20,00 RPM is used, it is to be
understood that this is not an upper limit. Because of the
extremely fast switching capability of the amorphous metal stator
arrangement and the precise activation and deactivation control of
the electromagnets provided by the control arrangement described
above, motor and generator devices designed in accordance with the
invention are capable of providing extremely high speed devices
with rotational speeds of 50,000 RPM or even greater than 100,000
RPM. The present invention also provides a stator arrangement
configuration and rotor arrangement configuration that are capable
of withstanding the extreme centrifugal forces that would be
generated by these extremely high speed devices.
[0051] In order to allow controller 46 to discretely detect the
presence of the openings of the various tracks in encoder disk 50,
the openings in the various tracks are slightly staggered relative
to one another such that the different optical sensors of array 52
are not trying to indicate the detection of the beginning of an
opening for different tracks at the same precise time. This
encoding configuration is commonly referred to as gray code and is
intended to prevent errors by the controller caused by very slight
inaccuracies in the locations of the position indicating
openings.
[0052] Referring back to FIG. 1, now that the various components
making up device 10 have been described, the operation of the
device in various modes will be described in more detail. Because
the amorphous metal magnetic core material is able to switch it's
magnetic field extremely quickly and because control arrangement 44
is able to activate and deactivate electromagnet assembly 34 at
extremely precise times, control arrangement 44 of the present
invention allows controller 46 to use any combination of a
plurality of electromagnet assembly activation and deactivation
parameters in order to control the speed, efficiency, torque, and
power of the device. These parameters include, but are not limited
to, the duty cycle activation time, the start/stop points of the
duty cycle activation time, and the modulation of the duty cycle
activation time. The activation and deactivation parameters will be
described in more detail with reference to FIGS. 5A-C, which are
graphs showing the activation/deactivation status of electromagnet
assembly 34 for two consecutive duty cycles D1 and D2.
[0053] The electromagnet assembly is activated having alternating
north and south polarity for each of the pole pieces making up the
electromagnet assembly. For any given stator pole piece, duty cycle
D1 corresponds to the time it takes for the rotor assembly to
rotate from a point where a north pole of one of the rotor magnets
is adjacent to and lined up top dead center with the given stator
pole piece to the time the south pole of the next successive rotor
magnet is adjacent to and lined up top dead center with the given
stator pole piece. As indicated by the reference letter N, the
electromagnet assembly is activated during duty cycle D1 such that
the given stator pole piece acts as a north pole. Duty cycle D2
corresponds to the time it takes for the rotor assembly to rotate
from the point where the south pole of the rotor magnet at the end
of duty cycle D1 is lined up top dead center with the given stator
pole piece to the time the north pole of the next successive rotor
magnet is lined up top dead center with the given stator pole
piece. As indicated by the reference letter S, the electromagnet
assembly is activated during duty cycle D2 such that the given
stator pole piece acts as a south pole.
[0054] As shown in FIG. 5A, the duty cycle activation time is the
continuous duration of time in which the electromagnet assembly 34
of the stator arrangement is activated for a given duty cycle. The
duty cycle activation time is indicated by the letter T in FIGS.
5A-C. The start/stop points of the duty cycle activation time are
the times at which the duty cycle activation time starts (indicated
by reference numeral 60) and stops (indicated by reference numeral
62) during the duty cycle relative to the rotational position of
the rotor. As illustrated in FIG. 5B, the start/stop time may be
changed while keeping the duty activation time T constant or it may
be changed while, at the same time, changing the length of duty
activation time T. And finally, the modulation of the duty cycle
activation time is the pulse width modulating of electromagnet
assembly 34 during the duty activation time T between its start and
stop points. As illustrated in FIG. 5C, this is done by activating
and deactivating electromagnet assembly 34 during what would
otherwise be the continuous duty cycle activation time T. While the
pulse width modulation is shown as equal ON and OFF pulses, the ON
pulses may be different in duration than the OFF pulses.
Furthermore, each set of pulses can vary among themselves to
provide a desired overall activation time within the time T. In
accordance with the invention, the speed, efficiency, and power and
torque input/output of device 10 may be controlled by using control
arrangement 44 to activate and deactivate electromagnet assembly 34
using any combination of these parameters, or any other
predetermined activation and deactivation parameters in some
combination.
[0055] When device 10 is stopped, controller 46 uses encoder disk
50 and optical sensor array 52 to determine the relative position
of rotor arrangement 16 relative to stator arrangement 18. In the
case of an electric motor, controller 46 uses the position
information to start the rotation of the rotor arrangement by
energizing electromagnet assembly 34 such that pole pieces 36 have
the appropriate polarity to start the rotation of the motor in the
desired direction. Controller 46 activates and deactivates
electromagnet assembly 34 such that the polarity of each pole piece
reverses for each successive duty cycle. Once the motor is rotating
at a sufficient speed, controller 46 only uses the outer tracks of
encoder disk 50 to determine the rotational speed of the rotor
assembly relative to the stator assembly for calibrating counter
arrangement 49. Controller 46 continues controlling device 10 by
using counter arrangement 49 and the signals produced by encoder
disk 50 to select and use predetermined device control settings
which may be programmed into or otherwise provided to controller 46
to control the activation and deactivation of electromagnet
assembly 34. Because control arrangement 44 is able to activate or
deactivate electromagnet assembly 34 at any one of the counts of
counter arrangement 49, control arrangement 44 is able to very
precisely control the speed, efficiency, torque, and power of
device 10 using any combination of the above described activation
and deactivation parameters.
[0056] The precision, speed, and flexibility of control arrangement
44 allows a device designed in accordance with the present
invention to be used for a wide variety of applications. Also, by
using super magnets in the rotor assembly and amorphous metal
magnetic cores, the device is capable of very high power densities
and very high rotational speeds compared to conventional electric
motors and generators. These advantages allow a device designed in
accordance with the present invention to be used in ways that have
not been previously possible or practical using conventional
devices.
[0057] In a first example, one preferred embodiment of the
invention is an electric motor for use in a numeric control machine
tool application in which multiple tools are driven using the same
spindle and chuck. In the case where the electric motor directly
drives the spindle and the motor and spindle are supported for
movement over a work surface, the spindle and overall tool would
not need to be constructed nearly as heavily because of the light
weight and high power density of the motor. Also, because of the
flexibility of the control arrangement of the motor, the motor may
be programmed for a wide variety of specific operations. For
instance, the tool may initially be used as a high speed,
relatively low power router rotating at for example 20,000 RPM.
Then, by driving the motor in the opposite direction, a the motor
and spindle may be stopped very quickly so that a different tool
may be automatically inserted into the chuck. If, for example, the
next operation is a lower speed, but higher power requirement
drilling operation, the control arrangement of the motor may be
programmed to provide the desired speed, efficiency, power, and
torque output. Using a motor in accordance with the present
invention, a much wider range of motor speed, power, and torque
settings are available compared to conventional motors.
[0058] In another application illustrated in FIG. 6, device 10 is
used as a generator which is driven by a windmill 100. In this
situation, control arrangement 44 is configured to switch the way
electromagnet assembly 34 is activated and deactivated in order to
vary the power generated by device 10 depending on the power input
available from windmill 100. This arrangement allows the generator
to operate in a much wider range of operating conditions than is
possible using conventional generators.
[0059] Typically windmill generators are configured to have a
predetermined electrical output. As the wind comes up, the
generator is not able to operate until the wind speed reaches a
minimum operating speed. Since typical windmills are designed to
operate at a point near the average wind speed for the area in
which they are installed, this means that the windmill is not able
to generate any power when the wind is below the minimum operating
speed of the windmill. As the wind increases beyond the designed
operating speed, the windmill must be feathered or have a breaking
mechanism to waste some of the wind energy in order to prevent the
windmill from over speeding. In some cases, the windmill must be
shut down altogether in very high wind situations to avoid damage
or over heating of the breaking mechanism. Therefore, in high wind
situations or very high wind situations, much or all of the
available wind energy goes to waste because the windmill generator
is only able to generate its predetermined electrical output.
[0060] In accordance with the invention, device 10 may be designed
to have a maximum power output which is more in line with the high
wind energy available to the windmill rather than the average wind
energy. In this situation, when the wind is at it's average wind
speed, control arrangement 44 connects and disconnects
electromagnet assembly 34 such that device 10 has a power output
substantially lower than it's maximum power output. In fact, in low
wind situations, device 10 may be used as an electric motor in
order to get the windmill started. Once rotating at an appropriate
speed, device 10 may be operated as a generator with a very low
power output. As the wind increases to higher than average wind
speeds, control arrangement 44 simply activates and deactivates
electromagnet assembly 34 such that the power output increases to
match the energy input of the wind. In very high wind situations in
which the wind energy is even greater than the maximum power output
of device 10, device 10 may be operated a certain fraction of the
time as an electric motor driving the windmill in the opposite
direction to act as a brake. This overall configuration allows the
windmill to operate and produce output in a much wider range of
wind conditions than is possible using conventional generators.
[0061] The power output of device 10 is controlled by activating
and deactivating electromagnet assembly 34 as described above. Any
combination of activation and deactivation parameters including the
duty cycle activation time, the start/stop points of the duty cycle
activation time, and the modulation of the duty cycle activation
time may be used to control the power output of device 10. By
controlling these activation and deactivation parameters, a very
wide range of power outputs may be achieved for any given sized
device. Also, because device 10 may be driven in either direction
as an electric motor by energizing electromagnet assembly 34 with
the appropriate polarity for any desired fraction of time during
it's operation, the device is able to reduce or increase the amount
of force required to turn the device as a generator. Therefore, the
device is able to act as a generator with an extremely wide range
of power outputs.
[0062] When device 10 is acting as a generator, the flexibility
provided by control arrangement 44 also allows device 10 to be
arranged to condition the power output of device 10 without
requiring the use of additional power conditioning devices. Using
the example of the windmill application illustrated in FIG. 6, as
described above, control arrangement 44 is able to activate and
deactivate electromagnet assembly 34 in order to control the power
output of device 10. Because of this control arrangement 44 is able
to control the speed at which the windmill operates. Also, control
arrangement 44 is able to control the activation and deactivation
parameters as described above. This allows control arrangement 44
to be configured to activate and deactivate the electromagnet
assembly such that the output of device 10 is conditioned to a
desired electrical output without requiring the use of additional
electrical power conditioning devices. This is done by controlling
the speed of the device and activating and deactivating the
electromagnet assembly at the appropriate times to create an
electrical output conditioned to a desired electrical output. In
the case where the output is desired to be pulsed DC, as would be
the case when charging batteries, an H bridge controller can
convert the AC output of the device to pulsed DC. This is known as
"active rectification".
[0063] As illustrated in FIG. 7, another application in which the
inventive device is well suited is a gas turbine driven generator
application. Because of the extremely high rotational speeds of
turbine engines, conventional generators are typically connected to
a turbine engine using reduction gears that substantially reduce
the rotational speed at which the generator is driven by the
turbine engine. These reduction gear arrangements increase the cost
of the overall system and cause energy loses that reduce the
overall efficiency of the combination. In accordance with the
present invention, a generator designed as described above is
directly driven by a gas turbine without the use of reduction gears
or any other arrangement for reducing the rotational speed at which
the turbine engine drives the generator. As shown in FIG. 7, device
10 is directly driven by turbine engine 200. Device 10 may also be
used as a starter motor for the turbine engine. As also described
above, because of the extremely high speed at which the amorphous
metal magnetic core of device 10 is able to respond to changes in
the magnetic field, and because of the extremely fast switching
capabilities of control arrangement 44, device 10 is able to
operate effectively at extremely high rotational speeds. This
allows device 10 to be directly driven by turbine engine 200, and
eliminates the need for any reduction gears or other arrangements
for reducing the rotational speed at which the turbine engine
drives device 10.
[0064] The disk or axial type device configuration described above
provides a compact overall package which may be designed to
withstand extremely high centrifugal forces. This allows a device
of this configuration to operate at extremely high rotational
speeds and therefore offer an extremely high power output for a
given size device. In one particularly interesting application, the
device is contemplated to be used as an electric motor to directly
drive a refrigeration unit turbo compressor at extremely high
rotational speeds. These rotational speeds may be 50,000 to 100,000
RPM or more. By operating the turbo compressor at these rotational
speeds, the efficiency of the compressor is substantially improved.
Using conventional electric motors which operate at much slower
speeds, most or all of the efficiency gain associated with the high
speed turbo compressor is lost to mechanical loses associated with
the gearing necessary to achieve the high rotational speed. By
directly driving the compressor with a high speed motor designed in
accordance with the invention, the efficiency losses associated
with the conventional gear assembly are eliminated. This provides
an overall arrangement that is substantially more efficient than
conventional arrangements.
[0065] Although the overall amorphous metal magnetic core 36 of
device 10 has been described as having an overall shape of a
toroidal ring with pole projections projecting out from one of the
annular surfaces of the ring as illustrated in FIG. 3A, this is not
a requirement. Instead, the overall amorphous metal magnetic core
may take any desired shape and still fall within the scope of the
invention so long as the overall amorphous metal core is made up of
a plurality of individually formed amorphous metal core pieces
which are supported adjacent one another by a core housing.
[0066] Referring to FIG. 8, the overall amorphous metal core may
take the form of U-shaped overall amorphous metal cores. In one
specific embodiment, three separate U-shaped overall cores 300
replace the toroidal ring configuration shown in FIG. 3A. Each core
300 is made up of three individually formed amorphous metal core
pieces 300a-c. Core pieces 300a and 300b are cylindrical core
pieces similar to core pieces 36a-f of FIG. 3A. However, core
pieces 300c are core pieces having an elongated oval
cross-sectional shape. In this embodiment, the stator housing would
have core piece openings arranged such that each pair of core
pieces 300a and 300b are held adjacent an associated one of core
pieces 300c. The electromagnet coil array for this embodiment would
be similar to that described above for device 10. The only
difference between the configuration described above using the
toroidal ring core piece and the U-shaped configuration is that the
toroidal ring configuration magnetically couples all six of the
pole pieces formed by core pieces 36a-f, whereas, in the U-shaped
configuration, only each associated pair of pole pieces formed by
core pieces 300a and 300b are magnetically coupled.
[0067] FIG. 9 illustrates another possible configuration for
providing the magnetic core of the present invention. As described
above, device 10 of FIG. 1 includes two stator arrangements
including overall amorphous metal cores 36, one on each side of
rotor arrangement 16. FIG. 9 illustrates a generally C-shaped
overall amorphous metal core 400 including five individually formed
amorphous metal core pieces 400a-e. The two toroidal ring overall
cores of FIG. 1 may be replaced with six overall amorphous metal
cores 400 positioned radially around the rotor arrangement. In this
embodiment, six core pieces 400a form pole pieces similar to pole
pieces 36a-f on one side of the rotor arrangement. Core pieces 400b
form corresponding pole pieces positioned on the other side of the
rotor arrangement. For each C-shaped overall amorphous metal
magnetic core 400, core pieces 400c-e form a magnetic yoke that
magnetically couples their associated core pieces 400a and 400b.
Also, in this embodiment, the stator housing would be configured to
support all of the various core pieces in their respective
positions to form the six overall C-shaped magnetic cores. As
described above with respect to the U-shaped cores, the only
difference between this embodiment and the embodiment of FIG. 1 is
that instead of all of the pole pieces on one side of the rotor
arrangement being magnetically coupled by the toroidal ring core
piece, each pair of pole pieces formed by associated core pieces
400a and 400b on opposite sides of the rotor arrangement are
magnetically coupled.
[0068] FIG. 10 illustrates yet another possible configuration for
providing the magnetic core of the present invention. In this case
the device takes the form of a barrel or radial type device rather
than a disk or axial type device. In this configuration, a rotor
assembly 500 would take the form of a barrel rather than a disk. In
this example, if the device is a DC brushless type motor, rotor
assembly 500 would included six rotor magnets 502 attached to the
outer circumferential edge of the rotor assembly. Alternatively, if
the device is an induction type motor, magnets 502 would not be
included and rotor assembly 500 would be made up of an
appropriately formed iron based material or other magnetic material
core.
[0069] The stator arrangement of this barrel type embodiment
includes only one overall amorphous metal core in the form of a
generally tubular shaped overall amorphous metal core 504. Core 504
is made up of a tubular shaped, individually formed amorphous metal
core piece 504a and six individually formed amorphous metal core
pieces or teeth 504b-g. Core piece 504a is formed by rolling a
continuous ribbon of amorphous metal material of a desired width
into the desired diameter tube shape. Core pieces 504b-g may be
formed by either stacking individual strips of amorphous metal
material to form the desired core piece shape or alternatively may
be formed by winding a continuous amorphous metal ribbon into a
very elongated oval shape. In this embodiment, a stator housing 506
has core piece openings arranged such that each of core pieces
504b-g are held adjacent to the inner surface of core piece 504a.
The electromagnet coil array for this embodiment would be similar
to that described above for device 10. The only difference between
the configuration described above using the toroidal ring core
piece and this barrel or radial configuration is that, for the
barrel configuration, the coils would be very elongated coils
running longitudinally parallel with the axis of the rotor assembly
and positioned around each of the core pieces or teeth 504b-g.
[0070] Although the various core pieces have been described
throughout the description as having specific cross-sectional
shapes, it should be understood that the invention is not limited
to these specific cross-sectional shapes. Instead, as illustrated
in FIGS. 11A-F, the individually formed core pieces may have any
cross-sectional shape including a circle, an oval, an egg shape, a
toroidal ring, a triangle having rounded corners, or a trapezoid
having rounded corners as illustrated by core pieces 510, 512, 514,
516, 518, and 520 in FIGS. 11A-F respectively.
[0071] Although the core pieces have been described as being wound
from a continuous ribbon of amorphous metal material, this is not a
requirement. Alternatively, the core pieces may be formed by
stacking individually formed strips or pieces of amorphous metal to
form a core piece of a desired shape such as a rectangular core
piece 522 or a trapezoidal cross-sectional shaped core piece 524,
as illustrated in FIGS. 11G and 11H, or a wide variety if other
particular cross-sectional shapes. As illustrated in these figures,
the individual strips may be stacked atop one another with each
piece being the same size and shape as indicated in FIG. 11G.
Alternatively, the individual strips may be stacked beside one
another with various individual pieces having different sizes and
shapes as illustrated in FIG. 11H. These various approaches allow a
wide variety of shapes to be formed.
[0072] As is known to those skilled in the art, when amorphous
metal material is produced, it typically has a particular direction
along which magnetic flux will be directed most efficiently. For a
ribbon of amorphous metal material, this direction is typically
either along the length of the ribbon or across the width of the
ribbon. By using the appropriate approach described above to form
each of the core pieces of an overall amorphous metal core, the
individual core pieces may be formed such that the amorphous metal
material is always oriented such that the magnetic flux is directed
through the pieces along the direction of the amorphous metal
material that most efficiently directs the magnetic flux. For
example, in the case of the toroidal ring embodiment of FIG. 3A,
toroidal ring core piece 36g would be made by winding an amorphous
metal ribbon which has its most efficient flux direction aligned
along the length of the ribbon. However, each of pole pieces 36a-f
would be formed by winding an amorphous metal ribbon which has its
most efficient flux direction aligned across the width of the
ribbon. This configuration aligns the amorphous metal material such
that the magnetic flux is directed through the core along the
direction of the material that most efficiently directs the
magnetic flux.
[0073] Although the invention has been described as a single phase
device in which all of the electromagnets of the stator assembly
are activated simultaneously, this is not a requirement. As would
be clear to one skilled in the art, the device of the invention may
also take the form of a multiphase device. FIG. 12 illustrates one
approach to providing a multiphase electric motor 600. In this
embodiment, three devices 10a-c designed as described above for
device 10 are mounted in line on a common shaft. Each of the
devices 10a-c is rotated twenty degrees relative to the previous
device. In other words, device 10b is rotated twenty degrees
relative to device 10a such that each of the pole pieces of the
stator arrangement in device 10b is fixed in a position twenty
degrees in advance of the corresponding pole pieces of the stator
arrangement of device 10a. The same is true for device 10c relative
to device 10b. Since the duty cycle of devices 10a-c can extend
through a sixty degree arc as described earlier, this configuration
causes the three devices to be out of phase with one another by one
third of their duty cycle. Thus, the three devices 10a-c may be
operated as an overall three phase device with each of the devices
10a-c corresponding to one phase.
[0074] Alternatively, as illustrated in FIG. 13, a three phase
device may be provided by constructing a device which includes a
stator arrangement having an electromagnet assembly 700 made up of
individually formed core pieces and three separately controllable
coil arrays. In this example, the rotor assembly (not shown in FIG.
13) would still have six rotor magnets as was the case for device
10 of FIG. 1. Similarly, the device includes two stator
arrangements with one positioned on each side of the rotor
arrangement as was also the case for device 10 of FIG. 1. However,
as shown in FIG. 13, which is a plan view of electromagnet assembly
700, this electromagnet assembly includes an overall amorphous
metal core 702 made up of nineteen individually formed amorphous
metal core pieces 702a-s. A first core piece 702a of the nineteen
core pieces is a toroidal ring core piece similar to core piece 36g
shown best in FIG. 3. Eighteen core pieces 702b-s are individually
wound core pieces having one end positioned adjacent toroidal ring
core piece 702a thereby forming eighteen pole projections.
Electromagnet assembly 700 also includes three separately
controllable coil arrays 704a-c. Each of the separately
controllable coil arrays is similar to coil array 38 of FIG. 1 with
each array including a coil wrapped around every third consecutive
one of core pieces 702b-s. With this arrangement, each coil array
corresponds to one of the phases of a three phase device.
[0075] Although the device has been described above as a three
phase device, it should be understood that the device may
alternatively be provided as a two phase device. In this case,
overall amorphous metal core 702 would include thirteen core pieces
rather than nineteen core pieces with twelve of the core pieces
forming pole pieces and one core piece acting as the magnetic yoke
as described above. Also, the two phase device would include only
two individually controllable coil arrays. Furthermore, it is to be
understood that the multiple phase devices are not limited to the
toroidal ring core configuration described above. Instead, the core
configuration may take on a wide variety of configurations and
still remain within the scope of the invention.
[0076] Although the above described embodiments have been describe
with the various components having particular respective
orientations, it should be understood that the present invention
may take on a wide variety of specific configurations with the
various components being located in a wide variety of positions and
mutual orientations and still remain within the scope of the
present invention. For example, although each stator arrangement of
device 10 was described as including six pole pieces and the rotor
was described as including six magnets, this is not a requirement.
Instead, the stator arrangement may have any desired number of pole
pieces and the rotor any number of magnets and still remain within
the scope of the invention.
[0077] Additionally, the present invention would equally apply to a
wide variety of electric motors and generators so long as the
stator arrangement of the device included an overall amorphous
metal core made up of individually formed core pieces which are
supported in place by a dielectric housing. These various
generators and motors include, but are not limited to, motors and
generators of the DC brushless type, DC synchronous type, variable
reluctance or switched reluctance type, induction type, and many
other types of generators, motors, and alternators. Therefore, the
present examples are to be considered as illustrative and not
restrictive, and the invention is not to be limited to the details
given herein, but may be modified within the scope of the appended
claims.
* * * * *