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Sommaire du brevet 2790300 

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(12) Brevet: (11) CA 2790300
(54) Titre français: MOTEUR A RELUCTANCE COMMUTEE
(54) Titre anglais: SWITCHED RELUCTANCE MOTOR
Statut: Réputé périmé
Données bibliographiques
Abrégés

Abrégé français

Moteur à reluctance commutée avec arbre rotor définissant un axe de rotation et disque rotor s'étendant de manière radiale par rapport à l'arbre rotor. Le disque rotor est doté de pôles espacés de manière égale et circonférentielle. Le moteur à reluctance commutée comporte aussi un assemblage de stator avec une multitude d'éléments de stator. Les éléments de stator sont espacés de manière égale et circonférentielle et alignés sur un plan commun perpendiculaire à l'axe de rotation et espacés de manière axiale par rapport au disque rotor pour former une fente d'aération axiale. Chaque élément de stator comporte une bobine de stator fournissant un flux magnétique par la fente d'aération axiale lorsqu'il est sous tension. Chaque deuxième élément de stator parmi la multitude d'éléments de stator forme un groupe respectif ce qui produit un premier groupe et un second groupe d'éléments de stator. Chaque élément du premier groupe est entouré de deux éléments du deuxième groupe de chaque côté. Le moteur à reluctance commutée comporte aussi un circuit de contrôle comprenant un ensemble redresseur demi-onde en direction avant et un ensemble redresseur demi-onde en sens inverse. Les bobines de stator du premier groupe sont reliées à l'ensemble redresseur demi-onde en direction avant et les bobines de stator du deuxième groupe sont reliées à l'ensemble redresseur demi-onde en sens inverse. Les deux assemblages de stator et le disque rotor peuvent être décalés en fonction d'un angle d'indexation.


Abrégé anglais

A switched reluctance motor (SRM) with a rotor shaft defining a rotational axis, a rotor disc extending radially from the rotor shaft, the rotor disc has rotor poles spaced equally circumferentially. The SRM also has a stator arrangement with a plurality of member stators. The member stators are spaced equally circumferentially and aligned in a common plane perpendicular to the rotational axis and axially spaced from the rotor disc for forming an axial air gap. Each of the member stators has a stator coil providing a magnetic flux in the axial air gap when energized. Every second member stator of the plurality of member stators forms a respective group, resulting in a first group and a second group of member stators, so that each member stator of the first group is surrounded by two members of the second group on each side. The SRM also has a control circuitry comprising a half-wave rectifier arrangement in a forward direction and a half-wave rectifier arrangement in a reverse direction; the stator coils in the first group are connected to the half-wave rectifier arrangement in the forward direction and the stator coils in the second group are connected to the half- wave rectifier arrangement in the reverse direction. Both the stator arrangement and the rotor disc may be offset by an index angle.

Revendications

Note : Les revendications sont présentées dans la langue officielle dans laquelle elles ont été soumises.





What is claimed is:


1. A switched reluctance motor comprising:
a rotor shaft defining a rotational axis;

a rotor disc extending radially from the rotor shaft, the rotor disc having a
first
plurality of rotor poles spaced equally circumferentially;

a stator arrangement having a second plurality of member stators; the second
plurality of member stators spaced equally circumferentially; the member
stators
aligned in a common plane perpendicular to the rotational axis and axially
spaced
from the rotor disc for forming an axial air gap; each of the member stators
having
a stator coil providing a magnetic flux in the axial air gap when energized,
the
magnetic flux in the axial air gap being parallel to the rotational axis;
every
second member stator of the second plurality of member stators forming a
respective group, resulting in a first group and a second group of member
stators,
and each member stator of the first group is surrounded by two members of the
second group on each side; and

a control circuitry comprising a half-wave rectifier arrangement in a forward
direction
and a half-wave rectifier arrangement in a reverse direction;

wherein the stator coils in the first group are connected to the half-wave
rectifier
arrangement in the forward direction and the stator coils in the second group
are
connected to the half-wave rectifier arrangement in the reverse direction.


2. The switched reluctance motor of claim 1, wherein the rotor disc is a first
rotor disc
and the stator arrangement is a first stator arrangement, further comprising:



25




a second rotor disc and a third rotor disc, each extending radially from the
rotor
shaft, the second rotor disc and the third rotor disc having the first
plurality of rotor
poles spaced equally circumferentially; and

a second stator arrangement and a third stator arrangement, each having an
identical configuration as the first stator arrangement;

wherein the control circuitry further comprises two half- wave rectifier
arrangements
in a forward direction and two half-wave rectifier arrangements in a reverse
direction;

wherein the stator coils in each of the first groups are connected to the half-
wave
rectifier arrangement in the forward direction and the stator coils in each of
the
second groups are connected to the half-wave rectifier arrangement in the
reverse direction; and

wherein two adjacent member stators define a stator sector angle and two
adjacent
rotor poles define a rotor sector angle.


3. The switched reluctance motor of claim 2, wherein the second rotor disc is
indexed
relative to the first rotor disc, and the third rotor disc is indexed relative
to the
second rotor disc.


4. The switched reluctance motor of claim 2, wherein the second stator
arrangement
is indexed relative to the first stator arrangement, and the third stator
arrangement
is indexed relative to the second stator arrangement.


5. The switched reluctance motor of claim 2, wherein the second rotor disc is
indexed
by a third of the rotor sector angle relative to the first rotor disc, and the
third rotor
disc is indexed by a third of the rotor sector angle relative to the second
rotor disc.


6. The switched reluctance motor of claim 2, wherein the second stator
arrangement
is indexed by a third of the rotor sector angle relative to the first stator


26




arrangement, and the third stator arrangement is indexed by a third of the
rotor
sector angle relative to the second stator arrangement.


7. The switched reluctance motor of claim 2, wherein the second rotor disc is
indexed
one sixth of the rotor sector angle relative to the first rotor disc, and the
third rotor
disc is indexed one sixth of the rotor sector angle to the second rotor disc.


8. The switched reluctance motor of claim 2, wherein the second stator
arrangement is
indexed one sixth of the rotor sector angle relative to the first stator
arrangement,
and the third stator arrangement is indexed one sixth of the rotor sector
angle to
the second stator arrangement.


9. The switched reluctance motor of claim 1, wherein the first plurality is
half of the
second plurality.


10. The switched reluctance motor of claim 1, wherein each of the member
stators has
a C-shaped core and wherein a back portion of the C-shaped core forms an air
gap.


11. The switched reluctance motor of claim 1, wherein the rotor pole is made
from
material selected from the group consisting of iron, steel including
electrical steel
and silicon steel, ferrite, amorphous magnetic, and perm alloy.


12. The switched reluctance motor of claim 1, wherein the rotor disc is made
from
material selected from the group consisting of aluminum, titanium, steels,
iron,
plastics including fiber-reinforced plastics, and ceramic.


13. The switched reluctance motor of claim 1, wherein the stator coils of the
member
stators in one of the first and second groups are connected in series or in
parallel.

14. The switched reluctance motor of claim 2, wherein the switched reluctance
motor
is powered by a three-phase AC.



27




15. A switched reluctance motor comprising:
a rotor shaft defining a rotational axis;

a rotor disc ring connected to the rotor shaft, the rotor disc ring having a
first plurality
of rotor poles spaced equally circumferentially;

a stator arrangement having a second plurality of member stators; the second
plurality of member stators spaced equally circumferentially; the member
stators
aligned in a common plane perpendicular to the rotational axis and axially
spaced
from an in side of the rotor disc ring for forming an axial air gap; each of
the
member stators having a stator coil providing a magnetic flux in the axial air
gap
when energized, the magnetic flux in the axial air gap being parallel to the
rotational axis; every second member stator of the second plurality of member
stators forming a respective group, resulting in a first group and a second
group
of member stators, and each member stator of the first group is surrounded by
two members of the second group on each side; and

a control circuitry comprising a half-wave rectifier arrangement in a forward
direction
and a half-wave rectifier arrangement in a reverse direction;

wherein the stator coils in the first group are connected to the half-wave
rectifier
arrangement in the forward direction and the stator coils in the second group
are
connected to the half-wave rectifier arrangement in the reverse direction.


16. The switched reluctance motor of claim 15, wherein each of the member
stators
has a C-shaped core and wherein a back portion of the C-shaped core forms an
air gap.


17. A method for generating torque by a switched reluctance motor, the method
comprising:

defining a rotational axis in a rotor shaft of the switched reluctance motor;


28




arranging a rotor disc with the rotor shaft, the rotor disc extending radially
from the
rotor shaft;

inserting a first plurality of rotor poles spaced equally circumferentially
into the rotor
disc;

arranging equally circumferentially a second plurality of member stators; the
second
plurality of member stators spaced;

aligning the member stators in a common plane perpendicular to the rotational
axis
and axially spaced from the rotor disc for forming an axial air gap; each of
the
member stators having a stator coil;

grouping every second member stator of the second plurality of member stators
to
form a first group and a second group of member stators, and each member
stator of the first group is surrounded by two members of the second group on
each side; and

providing a control circuitry comprising a half- wave rectifier arrangement in
a
forward direction and a half-wave rectifier arrangement in a reverse
direction,
connecting the stator coils in the first group to the half-wave rectifier
arrangement in
the forward direction;

connecting the stator coils in the second group to the half-wave rectifier
arrangement in the reverse direction; and

energizing the control circuitry and the stator coil to provide a magnetic
flux in the
axial air gap, the magnetic flux in the axial air gap being parallel to the
rotational
axis.



29




18. The method of claim 17, further comprising:

arranging a second rotor disc and a third rotor disc, each extending radially
from the
rotor shaft;

inserting a first plurality of rotor poles spaced equally circumferentially
into the
second rotor disc and the third rotor disc; and

arranging a second stator arrangement and a third stator arrangement, each
have
an identical configuration as the first stator arrangement;

wherein the control circuitry further comprises two half- wave rectifier
arrangements
in a forward direction and two half-wave rectifier arrangements in a reverse
direction;

wherein the stator coils in each of the first groups are connected to the half-
wave
rectifier arrangement in the forward direction and the stator coils in each of
the
second groups are connected to the half-wave rectifier arrangement in the
reverse direction.


19. The method of claim 18, wherein the second stator arrangement is indexed
relative to the first stator arrangement, and the third stator arrangement is
indexed
relative to the second stator arrangement.


20. The method of claim 18, wherein the second rotor disc is indexed by a
third of the
rotor sector angle relative to the first rotor disc, and the third rotor disc
is indexed
by a third of the rotor sector angle relative to the second rotor disc.



30

Description

Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.



CA 02790300 2012-09-25

SWITCHED RELUCTANCE MOTOR
BACKGROUND OF THE INVENTION

[0001] The present invention relates to an electric motor, and more
specifically, to a switched
reluctance motor.

[0002] Reluctance motors are well-known in the art. In general a reluctance
motor is a type of electric
motor that induces non-permanent magnetic poles on the rotor. Torque is
generated through
magnetic reluctance, i.e. by the tendency of the rotor to move to a position
where the magnetic
reluctance is minimal. One type of the reluctance motors is controlled by a
circuitry. The
circuitry determines the position of the rotor, and the windings of a phase
are energized as a
function of rotor position. This type of reluctance motor is generally
referred to as a switched
reluctance motor (SRM).

[0003] FIG. 1 (A) shows a schematic perspective view of an SRM. The
cylindrical stator 102 of the
SRM includes multiple inward projecting electromagnet poles 104, 106. The
poles protrude
from the inner diameter of the stator and point toward the open center of the
cylindrical stator.
The stator is periodically magnetized by a magnetic field, produced by a flow
of electric current
in windings 112 that encircle the poles of the stator. Nested concentricity in
the open center is
a rotor 107 having outwardly projecting poles 108, 110. Typically, the rotor
contains no circuitry
or permanent magnets. The rotor and the stator are coaxial. The rotor may be
made of soft
magnetic material, such as laminated silicon steel, and has multiple
projections 108, 110 acting
as salient magnetic poles through magnetic reluctance. The rotor is connected
to a rotor shaft
111 which is free to rotate and acts as an output shaft when the machine is
motoring.
Energizing of a stator causes a rotor pole to move into alignment with
corresponding stator
poles, thereby minimizing the reluctance of the magnetic flux path. Rotor
position information
may be used to control energizing of each phase to achieve smooth and
continuous torque.

[0004] FIG. 1 (B) is a schematic sectional view of the SRM. A coil 114 is
provided at each stator pole
116. The stator poles 116, 118 which are positioned opposite one another may
generally be
coupled to form a single phase. A phase is energized by delivering current to
the coil 114.
Switching devices are generally provided which allow the coil to be
alternately connected into
a circuit which delivers current to the coil when the phase is energized and
one which
089217000A I


CA 02790300 2012-09-25

separates the coil from a current source when the phase is de-energized, and
which may
recover energy remaining in the winding.

[0005] When a rotor pole 120 is equidistant from the two adjacent stator poles
118, 122, the rotor pole
120 is in the fully unaligned position. This is the position of maximum
magnetic reluctance for
the rotor pole 120. In the aligned position, two or more rotor poles 124,126
are fully aligned with
two or more stator poles 128, 130, and is a position of minimum reluctance.

[0006] Reluctance torque is developed in an SRM by energizing a pair of stator
poles when a pair of
rotor poles is in a position of misalignment with the energized stator poles.
The rotor torque is
in the direction that will reduce reluctance. Thus the nearest rotor pole is
pulled from the
unaligned position into alignment with the stator field i.e. a position of
less reluctance.
Energizing a pair of stator poles creates a magnetic north and south in the
stator pole pair.
Because the pair of rotor poles is misaligned with the energized stator poles,
the reluctance of
the stator and rotor is not at its minimum. The pair of rotor poles will tend
to move to a position
of minimum reluctance with the energized windings. The position of minimum
reluctance
occurs where the rotor and the energized stator poles are aligned.

[0007] In order to sustain rotation, the stator magnetic field must rotate in
advance of the rotor poles,
thus constantly pulling the rotor along. At a certain phase angle in the
rotation of the rotor poles
to the position of minimum reluctance, but near the position of minimum
reluctance is achieved,
the current is removed from the phase de-energizing the stator poles.
Subsequently, or
simultaneously, a second phase is energized, creating a new magnetic north and
south pole in
a second pair of stator poles. If the second phase is energized when the
reluctance between
the second pair of stator poles and the rotor poles is decreasing, positive
torque is maintained
and the rotation continues. Continuous rotation is developed by energizing and
de-energizing
the stator poles in this fashion. Some SRM variants may run on 3-phase AC
power. Most
modern designs are of the switched reluctance type, because electronic
commutation gives
significant control advantages for motor starting, speed control, and smooth
operation.

[0008] SRMs may be grouped by the nature of the magnetic field path as to its
direction with respect
to the axis of the motor. If the magnetic field path is perpendicular to the
axial shaft, which may
also be seen as along the radius of the cylindrical stator and rotor, the SRM
is considered as
radial.

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CA 02790300 2012-09-25

[0009] One problem associated with radial SRM is that the torque developed by
the motor is not
smooth. Torque drops off steeply when the phase angle of the rotor is between
the poles of the
stator, where the reluctance is at maximum, then increases as the phase angle
of the rotor
moves toward alignment with a stator pole, where the inductance is at maximum.
This rising
and falling torque phenomenon is known as "torque ripple".

[0010] Another problem of the prior art SRM is that the torque developed by
the motor is not sufficient
at low speed which is desirable in many applications.

[0011] Another problem more prominently associated with radial SRM is noise
and vibration. As the
reluctance of the radial SRM increases and decreases, the magnetic flux in
parts of the motor
changes accordingly, and deforms the shape of the rotor and stator poles
thereby decreasing
the separation space between the poles, resulting in ovalizing of the stator,
audible noise and
unwanted vibration.

[0012] In an effort to overcome the above mentioned problems, other SRMs are
designed to define
the magnetic flux paths to be parallel to the rotational axis of the rotor,
whereby the SRM is
is considered as axial. With the axial SRM designs, an upper U-shaped stator
is arranged above
the disc and a corresponding lower U-shaped stator is arranged below the disc.
An air gap is
formed between the poles of each stator pole and the disc. An air gap flux
path between the two
poles of the upper stator passes about the stator coil from one pole, through
the disc, and
through the other pole. Similarly, an air gap flux path between the two poles
of the lower stator
passes from one pole, through the disc, and to the other pole.

[0013] The problem of torque ripple may also be addressed by modifying the
motor control circuitry, for
example, by profiling the current in a phase during the active time period
when the phase is
energized, the rate of change in the magnetic flux can be controlled resulting
in less abrupt
changes in machine torque. This approach requires complex circuitry, and
therefore results in
higher design, manufacturing, and maintenance costs. A general description of
the operation
principle of SRM may be found at
http://services.eng.uts.edu.au/cempe/subjects JGZ/eet/EET
Switched%20Reluctance%20M
otor JGZ 7 3 05.pdf. Often, in order to reduce the torque ripple, complex
simulation, such as
described in
http://www.planet-rt.com/technical-document/real-time-simulation-and-control-
reluctance-mot
089217000A 3


CA 02790300 2012-09-25

or-drives-high-speed-operation, is needed. This will further result in complex
implementation of
the control circuitry.

[0014] Therefore, there is a need to a low torque ripple SRM which is easy to
manufacture and easy
to control. There is a further need to a high torque SRM at low speed. There
is a further need
to a low torque ripple SRM which can use a common 3-phase AC supply or a
simple control
circuitry. There is yet a further need for an SRM with flexible numbers of
stators and rotors.
SUMMARY OF THE INVENTION

[0015] According to one aspect of the present invention there is provided a
switched reluctance motor.
The switched reluctance motor comprises a rotor shaft defining a rotational
axis. A rotor disc
extends radially from the rotor shaft. The rotor disc has a first plurality of
rotor poles spaced
equally circumferentially. The switched reluctance motor further comprises a
stator
arrangement having a second plurality of member stators. The member stators
are spaced
equally circumferentially. The member stators are aligned in a common plane
perpendicular to
the rotational axis and axially spaced from the rotor disc for forming an
axial air gap. Each of the
member stators has a stator coil providing a magnetic flux in the axial air
gap when energized.
The magnetic flux in the axial air gap is parallel to the rotational axis.
Every second member
stator of the second plurality of member stators forms a respective group,
resulting in a first
group and a second group of member stators. Each member stator of the first
group is
surrounded by two members of the second group on each side. The switched
reluctance motor
further comprises a control circuitry comprising a half-wave rectifier
arrangement in a forward
direction and a half-wave rectifier arrangement in a reverse direction. The
stator coils in the first
group are connected to the half-wave rectifier arrangement in the forward
direction and the
stator coils in the second group are connected to the half-wave rectifier
arrangement in the
reverse direction.

[0016] According to another aspect of the present invention there is provided
a switched reluctance
motor. The switched reluctance motor comprises a rotor shaft defining a
rotational axis and a
rotor disc ring connected to the rotor shaft. The rotor disc ring has a first
plurality of rotor poles
spaced equally circumferentially. The switched reluctance motor further
comprises a stator
arrangement having a second plurality of member stators. The member stators
are spaced
equally circumferentially. The member stators are aligned in a common plane
perpendicular to
089217000A 4


CA 02790300 2012-09-25

the rotational axis and axially spaced from the rotor disc for forming an
axial air gap. Each of the
member stators has a stator coil providing a magnetic flux in the axial air
gap when energized.
The magnetic flux in the axial air gap is parallel to the rotational axis.
Every second member
stator of the second plurality of member stators forms a respective group,
resulting in a first
group and a second group of member stators. Each member stator of the first
group is
surrounded by two members of the second group on each side. The switched
reluctance motor
further comprises a control circuitry comprising a half-wave rectifier
arrangement in a forward
direction and a half-wave rectifier arrangement in a reverse direction. The
stator coils in the first
group are connected to the half-wave rectifier arrangement in the forward
direction and the
stator coils in the second group are connected to the half-wave rectifier
arrangement in the
reverse direction.

[0017] Preferably, the rotor disc is a first rotor disc and the stator
arrangement is a first stator
arrangement, the switched reluctance motor further comprises: a second rotor
disc and a
third rotor disc, each extending radially from the rotor shaft, the second
rotor disc and
the third rotor disc having the first plurality of rotor poles spaced equally
circumferentially; and a second stator arrangement and a third stator
arrangement,
each having an identical configuration as the first stator arrangement. The
control
circuitry further comprises two half- wave rectifier arrangements in a forward
direction
and two half-wave rectifier arrangements in a reverse direction. The stator
coils in each
of the first groups are connected to the half-wave rectifier arrangement in
the forward
direction and the stator coils in each of the second groups are connected to
the
half-wave rectifier arrangement in the reverse direction. Two adjacent member
stators
define a stator sector angle and two adjacent rotor poles define a rotor
sector angle.

[0018] Preferably, the second rotor disc is indexed relative to the first
rotor disc, and the third
rotor disc is indexed relative to the second rotor disc.

[0019] Preferably, the second stator arrangement is indexed relative to the
first stator
arrangement, and the third stator arrangement is indexed relative to the
second stator
arrangement.

08921700CA 5


CA 02790300 2012-09-25

[0020] Preferably, the second rotor disc is indexed by a third of the rotor
sector angle relative
to the first rotor disc, and the third rotor disc is indexed by a third of the
rotor sector
angle relative to the second rotor disc.

[0021] Preferably, the second stator arrangement is indexed by a third of the
rotor sector
angle relative to the first stator arrangement, and the third stator
arrangement is
indexed by a third of the rotor sector angle relative to the second stator
arrangement.

[0022] Preferably, the second rotor disc is indexed one sixth of the rotor
sector angle relative
to the first rotor disc, and the third rotor disc is indexed one sixth of the
rotor sector
angle to the second rotor disc.

10023 Preferably, the second stator arrangement is indexed one sixth of the
rotor sector
angle relative to the first stator arrangement, and the third stator
arrangement is
indexed one sixth of the rotor sector angle to the second stator arrangement.

[0024] Preferably, the first plurality is half of the second plurality.

[00251 Preferably, each of the member stators has a C-shaped core and a back
portion of the
C-shaped core forms an air gap.

[0026] Preferably, the rotor pole is made from material selected from the
group consisting of
iron, steel including electrical steel and silicon steel, ferrite, amorphous
magnetic, and
perm alloy.

[0027] Preferably, the rotor disc is made from material selected from the
group consisting of
aluminum, titanium, steels, iron, plastics including fiber-reinforced
plastics, and
ceramic.

[0028] Preferably, the stator coils of the member stators in one of the first
and second groups
are connected in series or in parallel.

[0029] Preferably, the switched reluctance motor is powered by a three-phase
AC.
089217000A 6


CA 02790300 2012-09-25

[0030] According to another aspect of the present invention there is provided
a method for generating
torque by a switched reluctance motor, the method comprising: defining a
rotational axis in
a rotor shaft of the switched reluctance motor; arranging a rotor disc with
the rotor
shaft, the rotor disc extending radially from the rotor shaft; inserting a
first plurality of
rotor poles spaced equally circumferentially into the rotor disc; arranging
equally
circumferentially a second plurality of member stators; the second plurality
of member
stators spaced; aligning the member stators in a common plane perpendicular to
the
rotational axis and axially spaced from the rotor disc for forming an axial
air gap; each
of the member stators having a stator coil; grouping every second member
stator of
the second plurality of member stators to form a first group and a second
group of
member stators, and each member stator of the first group is surrounded by two
members of the second group on each side; and providing a control circuitry
comprising a half- wave rectifier arrangement in a forward direction and a
half-wave
rectifier arrangement in a reverse direction, connecting the stator coils in
the first group
to the half-wave rectifier arrangement in the forward direction; connecting
the stator
coils in the second group to the half-wave rectifier arrangement in the
reverse
direction; and energizing the control circuitry and the stator coil to provide
a magnetic
flux in the axial air gap, the magnetic flux in the axial air gap being
parallel to the
rotational axis.

[0031] Preferably, the method further comprises: arranging a second rotor disc
and a third
rotor disc, each extending radially from the rotor shaft; inserting a first
plurality of rotor
poles spaced equally circumferentially into the second rotor disc and the
third rotor
disc; and arranging a second stator arrangement and a third stator
arrangement, each
have an identical configuration as the first stator arrangement; wherein the
control
circuitry further comprises two half- wave rectifier arrangements in a forward
direction
and two half-wave rectifier arrangements in a reverse direction; wherein the
stator coils
in each of the first groups are connected to the half-wave rectifier
arrangement in the
forward direction and the stator coils in each of the second groups are
connected to
the half-wave rectifier arrangement in the reverse direction.

089217000A 7


CA 02790300 2012-09-25

[0032] Preferably, the second stator arrangement is indexed relative to the
first stator
arrangement, and the third stator arrangement is indexed relative to the
second stator
arrangement.

[0033] Preferably, the second rotor disc is indexed by a third of the rotor
sector angle relative
to the first rotor disc, and the third rotor disc is indexed by a third of the
rotor sector
angle relative to the second rotor disc.

[0034] This summary of the invention does not necessarily describe all
features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS

[0035] These and other features of the invention will become more apparent
from the following
description in which reference is made to the appended drawings wherein:

FIG. 1 (A) is a partial perspective view of a prior art radial SRM;

FIG. 1 (B) is a sectional view of the prior art radial SRM of FIG. 1 (A);

FIG. 2 (A) is a partial perspective view of the SRM in accordance with one
embodiment of the
present invention;

FIG. 2 (B) is a partial view of a rotor and a member stator in the SRM in
accordance with one
embodiment of the present invention;

FIG. 2 (C) is a sectional view of a rotor and a member stator in the SRM in
accordance with one
embodiment of the present invention;

FIG. 3 (A) is a schematic view of a stator arrangement in accordance with one
embodiment of
the present invention;

FIG. 3 (B) is a schematic view of an exemplary rotor for use with the stator
arrangement of FIG.
3 (A);

FIG. 3 (C) is a schematic view of the stator arrangement of FIG. 3 (A) and the
rotor of FIG. 3 (B);
089217000A 8


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FIG. 4 shows a power converter which can be used to operate the axial SRM in
accordance
with one embodiment of the present invention;

FIG. 5 (A) is a schematic view of an SRM in accordance with another embodiment
of the
present invention;

FIG. 5 (B) is a schematic view of an SRM in accordance with another embodiment
of the
present invention;

FIG. 5 (C) illustrates a 3-phase, 48-stator arrangement in accordance with
another
embodiment of the present invention;

FIG. 5 (D) illustrates schematically a 6-phase 48-stator SRM in accordance
with another
embodiment of the present invention;

FIG. 6 (A) shows a star connection power converter for use with a three-phase
SRM in
accordance with one embodiment of the present invention;

FIG. 6 (B) shows a delta connection power converter for use with a three-phase
SRM
in accordance with one embodiment of the present invention:

FIG. 7 (A) shows a commercial sinusoidal power supply wave form;

FIG. 7 (B) shows the positive part of an irregular shaped wave form for
minimizing a
torque ripple;

FIG. 7 (C) depicts a three-phase power inverter;

FIG. 7 (D) shows a three-phase shaped wave form for minimizing a torque
ripple;
FIG. 8 shows an arrangement of stators inside a ring-shaped rotor; and

FIGS. 9 (A) and (B) illustrate an embodiment where the stators are in a linear
arrangement.

08921700CA 9


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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0036] Referring to FIG. 2 (A), a three-phase axial SRM 200 in accordance with
one
embodiment of the present invention is illustrated. The principal components
of the
SRM 200 include a stator arrangement 201 with a plurality of "C"-shaped member
stators 202, 204, 206, 208 and 210; and a rotor 212 comprising a rotor shaft
214 and
three radially extending rotor discs 216, 218, 220. The central longitudinal
axis 221 of
rotor shaft 214 is considered the rotational axis of the rotor 212. Each of
the rotor discs
216, 218, 220 has a plurality of rotor poles 222, 224, 226.

[0037] The "C"-shaped member stators 202, 204, 206, 208, 210 are axially
spaced from the
rotor discs 216, 218, 220 and rotor poles 222, 224, 226 for forming axial air
gaps. For
each of the rotor discs, for example, rotor disc 218, the associated "C"-
shaped
member stators 204, 206 are aligned in a common plane perpendicular to the
axis
221. As described below, the stator poles are also equally-spaced
circumferentially by
a common predetermined stator sector angle, resulting in the equally
circumferential
spacing of the member stators.

[0038] Each of the member stators 202, 204, 206, 208, 210 in the stator
arrangement is an
electromagnet with a C-shaped core and a stator coil 228, 230. Also referring
to FIGS.
2 (B) and 2 (C), when a stator coil 232 is energized, a magnetic flux 236 is
generated
within the C-shaped core and emerges from a back iron portion 242, 244 to
interact
with the rotor pole 234 and extends to the magnetic flux 236 between the gap
of the
stator 238 and the rotor pole 234. The orientation of the magnetic flux 236
extending
from the stator 238 and through the rotor poles 234 is axial, parallel to the
rotor shaft
214. The magnetic flux 236 through air gap 246 is shortened, that is, much
shorter
than in a conventional SRM, thus the magnetic flux 236 remains mainly in the
gap 246,
and extending only through the back iron portion 242, 244 of the member stator
pole
238 equivalent to about the axial thickness of the rotor disc 240. Generally,
a coil 232
for a phase is switched on and off, firstly to capture a rotor pole 234 of the
respective
rotor disc 240 in its magnetic field when on, and the phase is turned off when
the rotor
089217000A 10


CA 02790300 2012-09-25

pole is or is about fully aligned with certain member stator. Using
predetermined
switching of the phases to actuate the appropriate stator coil for the
corresponding
rotor disc, the desired rotor speed is achieved, as is control of forward or
reverse
rotation.

[0039] The rotor pole 234 can be configured such that the magnetic flux 236
through pole 234
is radially balanced, that is, there is no radially attractive and repulsive
forces across
the rotor disc towards the shaft. This arrangement substantially eliminates
the noise,
vibration and deformation of the motor due to the elimination of radial forces
in
conventional SRM.

[0040] Advantageously, the individual, short magnetic flux path of the member
stators
reduces the magnetic leakage, thus increases the effectiveness of the stator
arrangement. Less leakage enables closer positioning of stator poles, this
means
higher count of stator poles are practically possible, higher count of stator
poles are
difficult to implement with prior art radial SRM technology due to magnetic
leakage
affections. The higher count of stator poles in turn increases the torque of
the SRM,
and reduces the speed of the SRM. In some embodiments, no additional
mechanical
gear is needed to reduce the speed of the output. In operation, the short
magnetic flux
path further results in energy savings.

[0041] Advantageously, the individual member stators generally have the same
configuration,
and are more compact than the member stators in the prior art radial SRM.
Therefore,
the stator arrangement as illustrated in FIG. 2(A) is easy to manufacture,
reduces
manufacture material and cost, and can be assembled by automation.

[0042] Advantageously, the manufacture of the rotor poles may be further
simplified by
inserting the rotor poles into the rotor disc, thereby reducing the use of the
magnetic
material.

08921700CA
11


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[0043] Advantageously, the working magnetic flux path only passes the poles of
the rotor, not
necessarily the disc body. There is a variety of non-magnetic materials
suitable for use
as the rotor disc, with the rotor poles imbedded in the rotor disc. Magnetic
materials
suitable for magnetic poles of the rotor may include, but not limited to,
iron, steel
including electrical steel, ferrite, amorphous magnetic, perm alloy.
Preferably, the
magnetic poles are made of ferromagnetic material, such as motor iron, silicon
steel..
Non-magnetic materials suitable for rotor discs may include, but not limited
to,
aluminum, titanium, many stainless steels, plastics including fiber-reinforced
plastics,
ceramic, carbon-fiber. Preferably, the rotor discs are made of cast aluminum,
cast iron,
steel, plastic, The term "non-magnetic material" is intended to describe a
material that
is generally not susceptible to magnetic fields. The term "magnetic material"
refers to
materials that are susceptible to magnetic fields. Generally, the
ferromagnetic nature
of the magnetic material only appears after an external magnetic field is
applied.

[0044] Advantageously, the member stators in a stator arrangement may be
controlled
individually, or in groups, as will be described in more detail below.

[0045] FIG. 3 (A) is a schematic view of a stator arrangement 302 in
accordance with one
embodiment of the present invention. In the illustrated example, the stator
arrangement 302 has 48 member stators 304, 306, 308, 310, 312, 314. The member
stators are divided into two groups of 24 member stators each, as depicted by
the
black and white squares, respectively, in the illustrated embodiment, group A
is
depicted in white and group B is depicted in black. The member stators are
equally-spaced circumferentially by a predetermined stator sector angle, in
this
example 7.5 , with each member stator of the first group, e.g. group A, 304,
306, 308
surrounded by two member stators of the second group, e.g. group B, 310, 312,
314
on each side. Each member stator of the first or second group has therefore a
predetermined group sector angle, in this example 15 , with the next member of
the
same group.

089217000A 12


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[00461 The member stators of the first group (group A) 304, 306, 308 may be
connected in
any fashion provided that the current flowing through each coil of the member
stators
is the same. Likewise, the member stators of the second group (group B) 310,
312,
314 may be connected together in any fashion provided that the current flowing
through each coil of the member stators is the same. In other words, the
member
stators of the respective groups may be connected in series, in parallel or in
a
combination of serial and parallel connections.

[00471 FIG. 3 (B) is an exemplary rotor 320 for use with the stator
arrangement 302 of FIG.
3(A). The rotor disc 320 supports 24 rotor poles 322, 324, 326, which are
equally
spaced-apart circumferentially by a predetermined rotor sector angle, in this
example
, associated with the spacing of the member stators of the stator arrangement
302.
[00481 FIG. 3 (C) is a schematic view of the stator arrangement 302 with the
rotor 320, where
the relationship between the member stators of the stator arrangement 302 and
the
rotor poles of the rotor 320 is illustrated. The number of member stators in
one group
15 may correspond to the number of rotor poles of the rotor 320, i.e. the
group sector
angles between the member stators of one group of the stator arrangement 330
and
the rotor poles of the rotor 332 are the same. The group sector angle of the
member
stators and the rotor poles ensures that during each rotation of the rotor
disc 320 the
member stators of one group and the rotor poles simultaneously register. This
registration occurs repeatedly during each revolution, namely forty eight (48)
times in
FIG. 3 (C) corresponding to the total number of the member stators and the
number
of rotor poles. As rotor poles register with the member stators, the coils
associated with
the member stators of that group will be energized electrically just as the
rotor poles
near the air gaps of the member stators, to produce a motor torque and would
be
de-energized prior to reaching the fully registered state. The large number of
the rotor
poles and the member stators of a group permits generation of fairly
substantial
torques even at low speeds or at start-up.

08921700CA 13


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[0049] Referring to FIGS. 2 (B) and 3 (C), the arrangement of the member
stators in a group
and rotor poles results in the formation of local magnetic flux paths between
each of
the member stators 238 and the rotor poles 234. Referring to FIG. 2 (C), a
local
magnetic flux path 236 associated with a member stator 238 is shown. The
magnetic
flux path comprises the two poles 242, 244 and the rotor disk 240. The rotor
pole 234
is magnetically attracted by adjoining poles 242, 244. The rotor disc 240 does
not
contribute to the working magnetic flux path directly, so the rotor disc 240
can
therefore be formed of a light-weight non-magnetic material such as aluminum,
plastic
or any other suitable material. The formation of localized magnetic circuits
minimizes
the length of required magnetic paths thereby reducing power losses. The rotor
poles
are constructed of a multiplicity of identical magnetic material, for example
but not
limited to, motor iron. During assembly, the rotor poles may be simply
inserted or
embedded into the rotor disc 240.

[0050 Referring to FIG. 3 (A), the member stators of the stator arrangement
302 are
alternately connected to two groups, group A and group B. FIG. 4 shows a power
converter control circuitry which can be used to operate the axial SRM in
accordance
with one embodiment of the present invention. The control circuitry is shown
in
association with two groups, A and B, of the member stators in the stator
arrangement
302 as 402 and 404, respectively. Group A 402 of the member stators are
connected
to a half-wave rectifier arrangement in a reverse direction while group B 404
of the
member stators are connected to a second half- wave rectifier arrangement in a
forward direction. The terminal U is connected to a single phase AC. In
operation, the
positive half of the single phase AC wave passes through the group B 404 of
the
member stators. The negative half of the single phase AC wave passes through
the
group A 402 of the member stators. Advantageously, the coils in the group A of
the
member stators and the coils in the group B of the member stators are
energized in
sequence, and in synchronization with the phase of the single phase AC. This
produces a moving magnetic field which induces torque through adjacent rotor
poles.
The rotor disc rotates to move adjacent rotor poles inline with the energized
member
08921700CA 14


CA 02790300 2012-09-25

stator for minimizing the flux path. Advantageously, both the positive half
and the
negative half of the single phase AC wave contribute to the operation of the
axial SRM
of the present invention. Advantageously, referring to FIGS. 3 (A) and 3 (C),
since
twenty-four member stators are energized at the same time, a substantial
starting
torque can be developed.

[0051] Advantageously, the axial magnetic flux path is much shorter than prior
art motors
requiring less electrical steel. The rotor disc embodiment also requires less
copper coil
due to the elimination of conventional end connectors. Magnetic force is
balanced
radially, thus eliminating radial vibration. Less steel and less copper coils
result in
smaller, lighter, cooler and less expensive motors. The working magnetic flux
path is
purely axial, there is no component needed to conduct circumferential magnetic
flux.
[0052] The stator arrangement 302 and the rotor disc 320 can also be used in a
poly-phase
SRM, preferably, in a three-phase SRM, as illustrated in FIG. 5 (A). The use
of multiple
rotor discs conveniently enables multiple phases to be employed wherein one
phase
is influences one rotor disc, wherein half of the member stators for that
rotor disc are
energized at once. For the purpose of a simplified three dimensional
illustration, only
24 member stators and 12 rotor poles are shown in FIGS. 5 (A) and 5 (B).
Similar to
the arrangement described in FIG. 3 (A), the member stators of the stator
arrangements 502, 504, 506 are alternately connected to two groups, group A
and
group B. In other words, each member stator 526 in the first group is
surrounded by
member stators 527, 530 of the second group. The member stators are
equally-spaced circumferentially and define a common predetermined stator
sector
angle, the stator sector angle in the exemplary embodiment in FIG. 5 (A) is 15
. The
group sector angle between the consecutive member stators in the same group is
300.
The rotor poles are also equally-spaced circumferentially by another common
predetermined sector angle, the rotor sector angle in the exemplary embodiment
in
FIG. 5 (A) is 30 .

08921700CA 15


CA 02790300 2012-09-25

[0053] The SRM 500 includes three stator arrangements 502, 504, 506. Each of
the stator
arrangements 502, 504, 506 includes 24 "C"-shaped member stators 508-530. Each
stator arrangement engages a rotor disc with 12 rotor poles 532-548. For the
purpose
of better illustration, only those components necessary to understand the
operation of
the SRM have been illustrated, some of the member stators are removed to
expose
the rotor poles, and some of the stator coils are not shown. Three radially
extending
rotor discs 550, 552, 554, and a rotor shaft 558 form a rotor. The central
longitudinal
axis 560 of rotor shaft 558 is considered the rotational axis of the rotor.

[0054] For each of the rotor discs, for example, rotor disc 550, the
associated "C"-shaped
member stators 508, 510, 512, 514 are aligned in a common hypothetical plane
perpendicular to the axis 560. Each of the member stators 508-530 has a stator
coil
562, 564. For the purpose of better illustration, stator coils are not shown
on some
member stators 514, 518, 524. The stator arrangements of the second and third
phases are similarly configured. It is apparent that one stator arrangement of
each
phase is axially aligned with a stator arrangement of either of the other two
phases.
The stator arrangements, 502, 504, 506, respectively corresponding to the
first,
second and third phases of a three-phase power supply, are exemplary of this
axial
alignment.

[0055] Each rotor disc of the three radially extending rotor discs 550, 552,
554, may be offset
relative to previous rotor disc by an indexed angle.

[0056] In the illustrated example in FIG. 5 (A), rotor disc 552 is offset or
indexed relative to the
rotor disc 550 by one-third of the rotor sector angle, i.e. 10 . Every second
member
stator of the stator arrangement 502 is fully registered with one of the rotor
poles of the
rotor disc 550. The rotor poles of the rotor disc 552 are indexed count-
clockwise by
10 , and the rotor poles of the rotor disc 554 are indexed count-clockwise by
an
additional 100, in other words, the rotor poles of the rotor disc 554 are
indexed relative
to the rotor disc 550 by two-thirds of the rotor sector angle, namely, 20 .
The result is
that the rotor poles of one of the rotor discs 550, 552, 554, are positioned
for
089217000A 16


CA 02790300 2012-09-25

generation of torque tending to rotate the rotor shaft 558 forward if the
coils associated
with the particular phase are energized. In general, a rotor disc represents a
different
phase and the angular starting position of each rotor pole is angularly offset
or
indexed. Each rotor disc is secured to the rotor shaft 558 to maintain the
rotationally
indexed offset between the different phased stator arrangements 502, 504, 506.

[0057] In a second exemplary embodiment, as illustrated in FIG. 5 (B), the
three stator
arrangements 502, 504, 506 may also be offset relative to each other.

[0058] In this embodiment, stator arrangement 502 is indexed relative to
stator arrangement
504 by one-third of the rotor sector angle, i.e. 10 . Every second member
stator of the
stator arrangement 502 is fully registered with one of the rotor poles of the
rotor disc
550. The member stators of the stator arrangement 504 are indexed clockwise by
10 ,
and the member stators of the stator arrangement 506 are indexed clockwise by
an
additional 10 , in other words, the member stators of the stator arrangement
506 are
indexed by 20 . The result is that the rotor poles of one of the rotor discs
550, 552, 554,
are positioned for generation of torque tending to rotate the rotor shaft 558
forward if
the coils associated with the particular phase are energized.

[0059] In general, in a poly-phase SRM, for example, in the three-phase SRMs
as described
in FIGS. 5 (A) and 5 (B), the rotor discs may be adapted to be offset or
indexed relative
to the other rotor discs. Independently, the stator arrangements may be
adapted to be
offset or indexed relative to the other stator arrangements. Accordingly, at
any given
time, the member stators and rotor poles of at least one phase will be
oriented for
production of a forward torque when the associated coils are energized, or the
total
torque of the poly-phase SRM is a steady working torque.

[0060] Due to the compact size of the C-shaped member stators in the stator
arrangement,
more member stators can be used than the prior art SRM. In FIG. 5(C), a three-
phase
SRM with 48 member stators, 24 rotor-poles for each phase is depicted.

089217000A 17


CA 02790300 2012-09-25

[0061] According to embodiments of the present invention, the number of rotor
poles may be
any integer number, the member stators may be any even numbers. The stator
arrangement and the rotor disc embody modular construction principles,
therefore,
more stator discs can be added to the axial SRM of the present invention. FIG.
5 (D)
illustrates schematically a 6-phase 48-stator SRM in accordance with one
embodiment
of the present invention. In this example, the offset indexes for both rotor
and stator,
may be 1/6 of the rotor sector angle. The offset indexes result in a different
torque
pattern. Basically, an SRM can be built or an existing SRM of this
construction can be
expanded by adding additional rotor discs and stator arrangements so that
required
torque is achieved. The many possible permutations between the offsets stator
arrangements and the rotor discs can provide the desired torque
characteristics which
otherwise may be difficult to achieve or can only be achieved with complex
control
logic.

[0062] Advantageously, the three-phase SRMs as described in FIGS. 5 (A) and 5
(B) may be
driven by a simple star connection power converter described in FIG. 6 (A). or
a detla
connection power converter in FIG. 6 (B).

[0063] The basic single-phase power converter control circuitry described in
FIG. 4, may be
further connected in a star connection, as described in FIG. 6 (A). The
circuitry can be
divided into three phase groups 602, 604, 606, in association with the
exemplar
embodiments of FIGS. 5 (A) and 5 (B). Each of the phase groups 602, 604, 606
is
shown in association with two groups, Al and B1, A2 and B2, A3 and B3, of the
member stators in the stator arrangement 502, 504, 506, respectively. The
connection
U, V and W are connected to each of the phases of a three-phase power supply.
Group Al 608 of member stators are connected to a half-wave rectifier
arrangement in
a reverse direction while group B1 610 of member stators are connected to a
second
half-wave rectifier arrangement in a forward direction. The same arrangement
is
provided for half-wave rectifier arrangements connected to V and W. In
operation, the
positive half of the phase U wave passes through the group BI 610 of member
stators.
08921700CA 18


CA 02790300 2012-09-25

The negative half of the phase U wave passes through the group Al 608 of
member
stators.

[0064] Advantageously, the coils in the group Al member stators and the coils
in the group
B1 member stators are energized in sequence, and in synchronization with the
phase
U of the three phase AC. Likewise, the coils in group A2 member stators and
the coils
in the group B2 member stators are energized in sequence, and in
synchronization
with the phase V of the three phase AC, and the coils in the group A3 member
stators
and the coils in the group B3 member stators are energized in sequence, and in
synchronization with the phase W of the three phase AC. Advantageously, both
the
positive half and the negative half of AC wave contribute to the operation of
the axial
SRM of the present invention. Accordingly, as show in FIG.5 (A) , a 3-phase
24-stator-pole, 12-rotor-pole SRM, member stators can be energized a total of
twenty-four times during each revolution to generate motor torque.

[0065] FIG. 6 (B) shows an alternate power converter, with three basic single-
phase power
is converter control circuitries described in FIG. 4, in a delta configuration
suitable for the
axial SRM of the present invention. As discussed, the member stators of a
stator
arrangement may be connected in different configurations, provided that the
current
through the coils of the member stators of the respective groups is the same.
The coils
of the member stators may be, for example, connected in series. The power
converter
FIG. 6 (B) provides higher peak-to-peak voltages, therefore, it may be
suitable for
driving member stators arranged in series.

[0066] Referring to FIGS. 3 (A) - 3 (B) and 5 (A) - 5 (B), since twelve or
twenty-four member
stators are energized at the same time, a substantial starting torque can be
advantageously developed.

[0067] Advantageously, through the adjusting of the index angle of the rotor
discs and the
index angle of the stator arrangements of the poly-phase SRM, the torque
ripple can
be minimized or eliminated.

08921700OA 19


CA 02790300 2012-09-25

[0068] For example, for a three-phase SRM as described in FIG. 5 (A), the
index angle of the
rotor discs and the index angle of the stator arrangements may be the 1/6, 2/6
... of the
angles between the rotor poles. For a six-phase SRM as described in FIG. 5
(D), the
index angle of the rotor discs and the index angle of the stator arrangements
may be
the 1/12, 2/12... of the angles between the rotor poles. In general, for a M-
phase SRM,
the index angle of the rotor discs and the index angle of the stator
arrangements may
be the 1/(2M), 2/(2M) ... of the angles between the rotor poles.

[0069] Referring to FIG. 5 (A), the torque T1 generated by the first rotor
disc 550 is
T1=CT1+RT1(t)

wherein CT1 is the constant torque generated by first rotor disc 550, and
RT1(t) is the
variable torque at time t;

[0070] the torque T2 generated by the second rotor disc 552 is
T2=CT2+RT2(t)

wherein CT2 is the constant torque generated by the second rotor disc 552, and
RT2(t)
is the variable torque at time t;

[0071] the torque T3 generated by the third rotor disc 554 is
T3=CT3+RT3(t)

wherein CT3 is the constant torque generated by the third rotor disc 554, and
RT3(t) is
the variable torque at time t.

[0072] For a three-phase SRM as illustrated in FIG. 5 (A), total torque T is:
T= T1 +T2 +T3=CT1+RT1(t)+ CT2+RT2(t)+ CT3+RT3(t)

CT1, CT2 and CT3 are constants. RT1(t), RT2(t) and RT3(t) are time based
variables.
089217000A 20


CA 02790300 2012-09-25

[00731 RT,(t), RT2(t) and RT3(t) may be controlled through both the indexing
of the rotor discs
and the stator arrangement, and combined with different control algorithms. It
is
therefore possible to minimize the amplitude in RT1(t)+RT2(t)+RT3(t), and even
to
achieve the ideal result:

RT1(t) +RT2(t) + RT3(t) = constant

[0074] For example, for a three-phase AC power supply, the power for
sin (x) + sin (x - 2/3it) + sin (x - 4/3t) is constant,

[0075] For a three-phase triangle function f (x), the power for

RT1(t) +RT2(t) + RT3(t) =f (x) + f (x - 2/37c) + f (x - 4/3t) is also constant
where: x=2 7t f t

where: 2/3r =120 electrical phase angle, 4/37c=240 electrical phase angle in
three-phase sinusoidal function sin (x) and three-phase triangle function f
(x)

[0076] If T= T1 +T2 +T3=CT1+RT1(t)+ CT2+RT2(t)+ CT3+RT3(t)=constant, that
means there is
no torque ripple

[0077] Referring to FIGS. 4, 5 (A), 6 (A) and 6 (B), the provision of the
stator in two groups and
the arrangement of half-wave rectifiers in forward and reverse directions
simplify the
operation of the SRM, and have the advantage that both positive half and the
negative
half of the power supply contribute to the working torque of the SRM. A
commercial
power to drive the SRM, as illustrated in FIG. 7 (A) may be used.

[0078] The stator coil current waveform to drive an SRM in accordance with an
embodiment
of the present invention, for example but not limited to, with a minimum
torque ripple,
may have an irregular shape instead of a sinusoidal shape, as illustrated in
FIG. 7 (D).
089217000A 21


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A waveform may be considered as optimal when T= T1 +T2 +T3=CT1+RT1(t)+
CT2+RT2(t)+ CT3+RT3(t) is constant.

[0079] A power inverter, for example, a three-phase power inverter as
illustrated in FIG. 7 (C)
may be used to generate the three-phase optimal wave form as illustrated in
FIG. 7 (D)
to power the SRM as illustrated in FIGS. 5(A) or 5 (B). It should be apparent
to a
person skilled in the art that the both positive half and the negative half of
the
three-phase optimal wave form contribute to the operation working torque of
the SRM.
[00801 Other embodiments of the present invention include an arrangement of
stators inside
a ring-shaped rotor as illustrated in FIG. 8.

[0081] In the illustrated example, the stator arrangement 802 has 24 member
stators 804,
806, 808, 810 arranged inside the ring-shaped rotor 812. In the illustrated
embodiment, the ring-shaped rotor 812 has 12 rotor poles 814. The member
stators
may be divided into two groups of 12 member stators each, as indicated by 804,
810
and 806, 808, respectively. The member stators are equally-spaced
circumferentially
by a predetermined stator sector angle, in this example 15 , with each member
stator
of the first group, surrounded by two member stators of the second group on
each
side. Each member stator of the first or second group has therefore a
predetermined
group sector angle, in this example 30 , with the next member of the same
group.
Accordingly, each of the 12 rotor poles 814 also has the predetermined angle,
in this
example 30 , with the next rotor pole.

[0082] The member stators of the first group 804, 810 may be connected in any
fashion
provided that the current flowing through each coil of the member stators is
the same.
Likewise, the member stators of the second group 806, 808 may also be
connected
together in any fashion provided that the current flowing through each coil of
the
member stators is the same.

089217000A 22


CA 02790300 2012-09-25

[0083] It should be apparent to a person skilled in the art that the
arrangement described in
FIG. 8 can also used in a multi-phase arrangement, analogous to the
arrangement
described in FIGS. 5 (A) to 5 (D).

[0084] It should be further apparent to a person skilled in the art that the
connections
described in FIGS. 4, 6 (A) and 6 (B) are non-limiting, preferred embodiments.

[00851 FIGS. 9 (A) and (B) illustrate an embodiment where the stators are in a
linear
arrangement. The stators 902, 904, 906, 908 engage a rail, or slide way, 910
so that a
linear movement can be initiated. The stators may also be divided into two
groups, e.g.
stators 902 and 906 in a first group and stators 904 and 908 in a second
group. When
the two groups are connected to the half-wave rectifier arrangement described
in FIG.
4, the moving rail 910 moves forward in a linear fashion.

[0086] FIG. 9 (B) shows a group of three-phase linear arrangements 912, 914,
916. Each of
the stator arrangements 918, 920, 922 is offset to the other. It can also be
seen that
the distance between the poles 924, 926 on the rail is double the distance
between the
stators so that the poles interact with one group of the stators at a time. In
the
illustrated embodiment, the offset of stator 920 and 922 is preferably 1/3 or
2/3 of the
distance between the poles on rail 910.

[0087] While the patent disclosure is described in conjunction with the
preferred
embodiments, the scope of the claims should not be limited by the preferred
embodiments set forth in the examples, but should be given the broadest
interpretation consistent with the description as a whole. In the above
description,
numerous specific details are set forth in order to provide a thorough
understanding of
the present patent disclosure. The present patent disclosure may be practiced
without
some or all of these specific details. In other instances, well-known process
operations
have not been described in detail in order not to unnecessarily obscure the
present
patent disclosure.

08921700CA 23


CA 02790300 2012-09-25

[0088] The terminology used herein is for the purpose of describing particular
embodiments
only and is not intended to be limiting of the patent disclosure. As used
herein, the
singular forms "a", "an" and "the" are intended to include the plural forms as
well,
unless the context clearly indicates otherwise. It will be further understood
that the
terms "comprises" or "comprising", or both when used in this specification,
specify the
presence of stated features, integers, steps, operations, elements, and/or
components, but do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or groups
thereof.

[0089] It is further understood that the use of relational terms such as first
and second, and
the like, if any, are used solely to distinguish one from another entity,
item, or action
without necessarily requiring or implying any actual such relationship or
order between
such entities, items or actions.

[0090] An algorithm is generally, considered to be a self-consistent sequence
of acts or
operations leading to a desired result. These include physical manipulations
of
physical quantities. Usually, though not necessarily, these quantities take
the form of
electrical or magnetic signals capable of being stored, transferred, combined,
compared, and otherwise manipulated. It has proven convenient at times,
principally
for reasons of common usage, to refer to these signals as bits, values,
elements,
symbols, characters, terms, numbers or the like. It should be understood,
however,
that all of these and similar terms are to be associated with the appropriate
physical
quantities and are merely convenient labels applied to these quantities.

08921700CA 24

Dessin représentatif

Désolé, le dessin représentatatif concernant le document de brevet no 2790300 est introuvable.

États administratifs

Pour une meilleure compréhension de l'état de la demande ou brevet qui figure sur cette page, la rubrique Mise en garde , et les descriptions de Brevet , États administratifs , Taxes périodiques et Historique des paiements devraient être consultées.

États administratifs

Titre Date
Date de délivrance prévu 2014-05-20
(22) Dépôt 2012-09-25
Requête d'examen 2012-09-25
(41) Mise à la disponibilité du public 2012-12-25
(45) Délivré 2014-05-20
Réputé périmé 2017-09-25

Historique d'abandonnement

Il n'y a pas d'historique d'abandonnement

Historique des paiements

Type de taxes Anniversaire Échéance Montant payé Date payée
Requête d'examen 400,00 $ 2012-09-25
Le dépôt d'une demande de brevet 200,00 $ 2012-09-25
Taxe finale 150,00 $ 2014-03-04
Taxe de maintien en état - brevet - nouvelle loi 2 2014-09-25 50,00 $ 2014-09-12
Taxe de maintien en état - brevet - nouvelle loi 3 2015-09-25 50,00 $ 2015-07-29
Titulaires au dossier

Les titulaires actuels et antérieures au dossier sont affichés en ordre alphabétique.

Titulaires actuels au dossier
YUAN, DEFANG
Titulaires antérieures au dossier
S.O.
Les propriétaires antérieurs qui ne figurent pas dans la liste des « Propriétaires au dossier » apparaîtront dans d'autres documents au dossier.
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Description du
Document 
Date
(yyyy-mm-dd) 
Nombre de pages   Taille de l'image (Ko) 
Page couverture 2012-12-28 1 38
Abrégé 2012-09-25 1 32
Description 2012-09-25 24 1 180
Revendications 2012-09-25 6 226
Dessins 2014-01-27 10 353
Page couverture 2014-04-29 1 38
Correspondance 2012-10-25 1 34
Correspondance 2012-10-30 1 13
Cession 2012-09-25 6 165
Poursuite-Amendment 2012-10-18 1 24
Poursuite-Amendment 2013-01-17 1 18
Poursuite-Amendment 2014-01-07 2 58
Poursuite-Amendment 2014-01-27 14 456
Correspondance 2014-03-04 2 47
Taxes 2014-09-12 1 33