U.S. patent application number 14/314510 was filed with the patent office on 2015-12-31 for sensorless control of switched reluctance machines for low speeds and standstill.
The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Carlos Nino Baron, Jesse Gerdes, Seok-hee Han, Ernesto Inoa, Ahmed Khalil, James Michael Thorne, Jackson Wai.
Application Number | 20150381087 14/314510 |
Document ID | / |
Family ID | 54931590 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150381087 |
Kind Code |
A1 |
Han; Seok-hee ; et
al. |
December 31, 2015 |
Sensorless Control of Switched Reluctance Machines for Low Speeds
and Standstill
Abstract
A method for determining rotor position of a switched reluctance
(SR) machine having a rotor and a stator is provided. The method
may include injecting a test pulse into one or more idle phases of
the SR machine, determining a decoupled flux value based at least
partially on a total flux value corresponding to the test pulse and
a mutual flux value, and determining the rotor position based at
least partially on the decoupled flux value.
Inventors: |
Han; Seok-hee; (Dunlap,
IL) ; Baron; Carlos Nino; (Peoria, IL) ; Wai;
Jackson; (Dunlap, IL) ; Khalil; Ahmed;
(Peoria, IL) ; Inoa; Ernesto; (Dunlap, IL)
; Gerdes; Jesse; (Dunlap, IL) ; Thorne; James
Michael; (Peoria, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Family ID: |
54931590 |
Appl. No.: |
14/314510 |
Filed: |
June 25, 2014 |
Current U.S.
Class: |
318/400.33 |
Current CPC
Class: |
H02P 6/18 20130101; H02P
25/08 20130101; H02P 27/06 20130101; H02P 25/089 20160201; H02P
6/185 20130101 |
International
Class: |
H02P 6/18 20060101
H02P006/18 |
Claims
1. A method for determining rotor position of a switched reluctance
(SR) machine having a rotor and a stator, comprising: injecting a
test pulse into one or more idle phases of the SR machine;
determining a decoupled flux value based at least partially on a
total flux value corresponding to the test pulse and a mutual flux
value; and determining the rotor position based at least partially
on the decoupled flux value.
2. The method of claim 1, wherein the test pulse is configured to
have a substantially constant current height.
3. The method of claim 1, wherein the test pulse is injected based
at least partially on a measured phase current and rotor position
feedback.
4. The method of claim 1, wherein the total flux value is
determined based at least partially on a voltage integration of the
test pulse.
5. The method of claim 1, wherein the mutual flux value is
determined based on one or more predefined relationships between
mutual flux values, measured phase current values, and rotor
position feedback values.
6. The method of claim 1, wherein the decoupled flux value is
determined based at least partially on a difference between the
total flux value and the mutual flux value.
7. The method of claim 1, wherein the rotor position is determined
based on one or more predefined relationships between decoupled
flux values, measured phase current values, and rotor position
values.
8. The method of claim 1, wherein the rotor position is used to
further derive a speed and a direction of the rotor relative to the
stator.
9. A control system for a switched reluctance (SR) machine having a
rotor and a stator, comprising: a converter circuit in electrical
communication between the stator and a common bus; and a controller
in electrical communication with at least the converter circuit,
the controller being configured to inject a test pulse into one or
more idle phases of the SR machine, determine a decoupled flux
value based at least partially on a total flux value corresponding
to the test pulse and a mutual flux value, and determine the rotor
position based at least partially on the decoupled flux value.
10. The control system of claim 9, wherein the controller is
configured to inject the test pulse to have a substantially
constant current height.
11. The control system of claim 9, wherein the controller is
configured to measure phase current and monitor rotor position
feedback.
12. The control system of claim 9, wherein the controller is
configured to determine the total flux value by integrating a
voltage of the injected test pulse.
13. The control system of claim 9, wherein the controller is
configured to determine the mutual flux value by referring to one
or more preprogrammed maps defining relationships between mutual
flux values, measured phase current values, and rotor position
feedback values.
14. The control system of claim 9, wherein the controller is
configured to determine the decoupled flux value by computing a
difference between the total flux value and the mutual flux
value.
15. The control system of claim 9, wherein the controller is
configured to determine the rotor position by referring to one or
more preprogrammed maps defining relationships between decoupled
flux values, measured phase current values, and rotor position
values.
16. The control system of claim 9, wherein the controller is
further configured derive a speed and a direction of the rotor
relative to the stator based on the rotor position.
17. An electric drive, comprising: a switched reluctance (SR)
machine having a stator and a rotor rotatably disposed relative to
the stator; a converter circuit configured to electrically
communicate with the stator and a common bus; and a controller in
electrical communication with at least the converter circuit, the
controller being configured to inject a test pulse into one or more
idle phases of the SR machine, determine a decoupled flux value
based at least partially on a total flux value corresponding to the
test pulse and a mutual flux value, and determine the rotor
position based at least partially on the decoupled flux value.
18. The electric drive of claim 17, wherein the controller is
configured to generate the test pulse to have a substantially
constant current height, and inject the test pulse based at least
partially on a measured phase current and rotor position
feedback.
19. The electric drive of claim 17, wherein the controller is
configured to determine the total flux value by integrating a
voltage of the injected test pulse, determine the mutual flux value
by referring to one or more preprogrammed maps defining
relationships between mutual flux values, measured phase current
values, and rotor position feedback values, and determine the
decoupled flux value by computing a difference between the total
flux value and the mutual flux value.
20. The electric drive of claim 17, wherein the controller is
configured to determine the rotor position by referring to one or
more preprogrammed maps defining relationships between decoupled
flux values, measured phase current values, and rotor position
values.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to switched
reluctance machines, and more particularly, to sensorless systems
and methods for controlling switched reluctance machines.
BACKGROUND
[0002] An electric machine such as an electrical motor, power
generation system, genset, or the like, is generally used to
convert one form of energy into another and may operate in a
motoring mode to convert electrical input into rotational or
otherwise mechanical output, or operate in a generating mode to
convert rotational or otherwise mechanical input into electrical
output. Among the various types of machines available for use with
an electric drive, switched reluctance (SR) machines have received
great interest for being robust and cost-effective. While currently
existing systems and methods for controlling such electric machines
provide adequate control, there is still room for improvement.
[0003] Among other factors, proper determination of the position of
the rotor relative to the stator of the SR machine, while at rest
or at an otherwise substantially low machine speed, is important to
the performance and efficiency of the SR machine. Some conventional
control schemes rely on a mechanically aligned speed wheel and
sensors to detect and determine the position of the rotor relative
to the stator at machine standstill or low speed operations. These
control schemes typically require costly and complex
implementations and are still susceptible to error. For instance,
an error of 2 degrees in the detected mechanical rotor position of
an SR machine, caused by a skewed sensor, a mechanical misalignment
of the speed wheel, or the like, may correspond to a 0.5% decrease
in efficiency of the electric drive assembly at full load.
[0004] Sensorless control schemes can also be used to derive the
rotor position using electrical characteristics of the SR machine.
For example, the control system of U.S. Pat. No. 5,525,886 to
Lyons, et al. injects a current signal having fixed voltage
frequency and varying current height to compute a total voltage
flux in the SR machine. Lyons then determines the rotor position
based on the voltage flux and the phase current. While Lyons may
provide more simplicity over sensor-based schemes, the voltage
integrator in Lyons still accumulates offset errors at least during
the measurement path and in estimating the voltage flux. Such error
accumulation can be compounded and adversely affects the accuracy
of rotor position detection especially during low machine speeds
and standstill.
[0005] Accordingly, there is a need to provide a control system or
scheme for controlling SR machines that is less costly and easier
to implement without compromising overall performance. Moreover,
there is a need to provide a control system or scheme that does not
rely on rotor position sensors, and further, substantially reduces
accumulation of offset errors to provide for more accurate, more
reliable and more efficient operation of an SR machine at
standstill or low machine speeds. The systems and methods disclosed
are directed at addressing one or more of these needs.
SUMMARY OF THE DISCLOSURE
[0006] In one aspect of the present disclosure, a method for
determining rotor position of a switched reluctance (SR) machine
having a rotor and a stator is provided. The method may include
injecting a test pulse into one or more idle phases of the SR
machine, determining a decoupled flux value based at least
partially on a total flux value corresponding to the test pulse and
a mutual flux value, and determining the rotor position based at
least partially on the decoupled flux value.
[0007] In another aspect of the disclosure, a control system for an
SR machine having a rotor and a stator is provided. The control
system may include a converter circuit in electrical communication
between the stator and a common bus, and a controller in electrical
communication with at least the converter circuit. The controller
may be configured to inject a test pulse into one or more idle
phases of the SR machine, determine a decoupled flux value based at
least partially on a total flux value corresponding to the test
pulse and a mutual flux value, and determine the rotor position
based at least partially on the decoupled flux value.
[0008] In yet another aspect of the disclosure, an electric drive
is provided. The electric drive may include an SR machine having a
stator and a rotor rotatably disposed relative to the stator, a
converter circuit configured to electrically communicate with the
stator and a common bus, and a controller in electrical
communication with at least the converter circuit. The controller
may be configured to inject a test pulse into one or more idle
phases of the SR machine, determine a decoupled flux value based at
least partially on a total flux value corresponding to the test
pulse and a mutual flux value, and determine the rotor position
based at least partially on the decoupled flux value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic view of an exemplary embodiment of an
electric drive with a control system for controlling a switched
reluctance (SR) machine;
[0010] FIG. 2 is a flow diagram of an algorithm or method for
determining the rotor position of an SR machine; and
[0011] FIG. 3 is a diagrammatic view of one exemplary control
scheme for operating an SR machine.
DETAILED DESCRIPTION
[0012] Reference will now be made in detail to specific embodiments
or features, examples of which are illustrated in the accompanying
drawings. Generally, corresponding reference numbers will be used
throughout the drawings to refer to the same or corresponding
parts.
[0013] FIG. 1 schematically illustrates an exemplary electric drive
100 that may be employed to communicate power between a first drive
component 102 and a second drive component 104. The first drive
component 102 may include a primary power source, such as a diesel
engine, a gasoline engine, a natural gas engine, or any other
source of mechanical or rotational energy commonly used in
association with mobile tools, industrial machines, and the like.
The first drive component 102 may alternatively include a primary
power source used in conjunction with stationary applications, such
as windmills, hydro-electric dams, batteries, fuel cells, or any
other suitable source of energy. The first drive component 102 may
also include electrical loads, such as motors for driving wheels,
tracks, or other traction devices which may be driven during
motoring modes of operating the electric drive 100. The second
drive component 104 may also include loads, or one or more devices
or components which consume and/or employ electrical power provided
thereto by the electric drive 100. For example, with respect to
industrial work machines or mobile work vehicles, the second drive
component 104 may include one or more motors for operating tools of
the machine and/or one or more traction motors for causing motion
of the vehicle.
[0014] Moreover, mechanical energy that is supplied by the first
drive component 102 may be converted into electrical power by the
electric drive 100 for use by the second drive component 104.
Conversely, any electrical power that is supplied by the second
drive component 104 and/or the electric drive 100 may be supplied
to drive mechanical power to the first drive component 102. As
shown in the particular embodiment of FIG. 1, for instance, the
electric drive 100 may communicate with the first drive component
102 through a switched reluctance (SR) machine 106, or the like. As
is well known in the art, the SR machine 106 may include a rotor
110 that is rotatably disposed within a fixed stator 112. The rotor
110 of the SR machine 106 may be rigidly and rotatably coupled to
an output of the first drive component 102 via a coupling 108, or
in other embodiments, via a direct crankshaft, a gear train, a
hydraulic circuit, or the like. Each phase or phase winding of the
stator 112 of the SR machine 106 may be electrically coupled to a
common bus 114 of the electric drive 100 via a converter circuit
116.
[0015] During a generating mode of operation, as the rotor 110 of
the SR machine 106 is rotated within the stator 112 by the first
drive component 102, electrical current may be induced within the
stator 112 and supplied to the converter circuit 116. The converter
circuit 116 may in turn convert the electrical signals into the
appropriate direct current (DC) voltage for distribution to the
electrical load 104 and/or any other device via the common bus 114.
The common bus 114 may provide terminals 118, such as positive and
negative or ground lines, across which the common bus 114 may
communicate a bus voltage or DC link voltage between one or more
electrically parallel devices of the electric drive assembly 100.
The load 104 may include circuitry for converting the DC voltage
supplied by the converter circuit 116 into the appropriate
electrical signals for operating any one or more devices associated
with the electric drive 100. Additionally, during a motoring mode
of operation, or when the electrical load 104 becomes the sink of
electrical power, the SR machine 106 may be enabled to cause
rotation of the rotor 110 in response to electrical signals that
are provided to the stator 112 from the common bus 114.
[0016] As shown in FIG. 1, the converter circuit 116 may include a
series of transistors or gated switches 120 and diodes 122 for
selectively enabling one or more phase windings or phases of the SR
machine 106. A three-phase SR machine 106, for example, may be
driven using a converter circuit 116 with six switches 120 and six
diodes 122 for selectively enabling or disabling each of the three
phases of the SR machine 106. Each of the switches 120 may further
be enabled or disabled via gate signals while an external or
secondary power source 124 provides power across the positive and
negative lines 118 of the common bus 114 to force current through
the respectively enabled switches 120 and diodes 122.
[0017] Still referring to FIG. 1, the electric drive 100 may also
be provided with an exemplary control system 126 configured to,
among other things, determine the position of the rotor 110 of the
SR machine 106 relative to the stator 112 and control operation of
the SR machine 106 based on the determined rotor position. As
illustrated in FIG. 1, the control system 126 may generally include
the converter circuit 116, at least one controller 128 in
communication with the gated switches 120 of the converter circuit
116, as well as a memory 130 in communication with the controller
128 that is provided within and/or external to the controller 128.
More particularly, the controller 128 may be electrically coupled
to the switches 120 in a manner which enables the controller 128 to
selectively engage the switches 120 and source current through the
different phases of the SR machine 106, as well as in a manner
which enables the controller 128 to monitor electrical
characteristics of the SR machine 106 and the bus or DC link
voltage of the common bus 114 during operation of the SR machine
106. The memory 130 may retrievably store one or more algorithms,
machine data, predefined relationships between different machine
parameters, preprogrammed models, such as in the form of lookup
tables and/or maps, or any other information that may be accessed
by the controller 128 and relevant to the operation of the SR
machine 106.
[0018] The controller 128 may be implemented using one or more of a
processor, a microprocessor, a microcontroller, a digital signal
processor (DSP), a field-programmable gate array (FPGA), an
electronic control module (ECM), an electronic control unit (ECU),
or any other suitable means for electronically controlling
functionality of the control system 126. The controller 128 may be
configured to operate according to predetermined algorithms or sets
of instructions for operating the electric drive 100 and the SR
machine 106 based on the rotational speed and/or position of the
rotor 110 relative to the stator 112 or other operating
characteristics of the electric drive 100. Such algorithms or sets
of instructions may be preprogrammed or incorporated into memory
130 that is associated with or at least accessible to the
controller 128 as is commonly used in the art.
[0019] Turning now to FIG. 2, one exemplary algorithm or method 132
for controlling an SR machine 106 is provided. More specifically,
the method 132 may be used to configure the controller 128 to at
least assess or determine the position of a rotor 110 relative to
the stator 112 of an SR machine 106, such as during machine
standstill or low speed operations, and to operate the SR machine
106 according to the determined rotor position. Each iteration of
the method 132 shown in FIG. 2 may be repeated per cycle, per
phase, or any other predefined duration or count, and performed at
least for as long as the SR machine 106 is in standstill or
operating at substantially low speeds. In other embodiments, any
one or more of the blocks or functions of the method 132 may also
be performed during other operating modes or operating speeds of
the SR machine 106. Furthermore, as it will be understood by those
of ordinary skill in the relevant art, any one or more of the
blocks or functions of the method 132 may be omitted, substituted,
rearranged or otherwise modified for different applications while
providing comparable results.
[0020] As shown, the controller 128 in block 132-1 may initially
monitor the operating state of the SR machine 106 to detect when
the machine speed is zero, approximately zero, or an otherwise
relatively low speed, such as when compared to the rise time of
phase current. The controller 128 may determine the operating state
of the SR machine 106 by monitoring the rotational speed of the
rotor 110 of the SR machine 106 relative to the stator 112,
monitoring the operating state of the first drive component 102
and/or coupling 108, monitoring corresponding electrical properties
of the common bus 114 and/or converter circuit 116, or the like. If
the SR machine 106 is operating at relatively higher speeds where
offset errors in machine measurements may be negligible, the
controller 128 may continue monitoring for standstill or low speed
operations where errors may be more prevalent. If the controller
128 in block 132-1 determines that the SR machine 106 is in
standstill or operating at relatively low speeds, the controller
128 may be configured to proceed to block 132-2 to determine the
position of the rotor 110 relative to the stator 112.
[0021] In accordance with block 132-2 of the method 132 of FIG. 2,
the controller 128 may be configured to inject a diagnostic or test
pulse into the relevant phases of the SR machine 106. In
particular, the controller 128 may be configured to selectively
enable corresponding switches 120 of the converter circuit 116 in a
manner which drives a phase current through at least each idle
phase of the stator 112, or only those phases that are not
controlling the SR machine 106 at a given instance. The controller
128 may be configured to generate a test pulse with a substantially
constant current height so as to facilitate further computations
which may be performed later, such as computations associated with
decoupling or compensating for flux due to mutual coupling, or the
like. Furthermore, the controller 128 may be configured to generate
and inject the test pulse into idle phases according to feedback
pertaining to the last known or most recent assessment of the rotor
position. Once the test pulse is injected, the controller 128 in
block 132-3 may be configured to compute the corresponding total
flux induced in those phases of the SR machine 106 into which the
test pulse was injected. Moreover, based on preprogrammed
relationships between flux, voltage and current, as well as
predetermined electrical properties of the SR machine 106, the
controller 128 may be configured to compute the total flux value by
integrating the total voltage of the test pulse over the duration
thereof.
[0022] Based at least partially on the total flux value, the
controller 128 may determine a self-induced or decoupled flux value
in block 132-4 of FIG. 2. More specifically, the controller 128 may
be preprogrammed to compute or determine the decoupled flux value
based on a difference between the total flux value and a mutual
flux value, or the flux due to mutual coupling within the SR
machine 106 for each idle phase. The controller 128 may be
configured to determine the mutual flux value by direct computation
or by reference to predefined models or relationships programmed
into the memory 130 associated with the controller 128. In
particular, the memory 130 may retrievably store one or more
preprogrammed lookup tables, maps, or the like, which correlate
different possible operating states of the SR machine 106 with
different mutual flux values. For example, the preprogrammed models
may output or suggest to the controller 128 the mutual flux value
that best corresponds to the measured phase current, the rotor
position feedback, and/or any other relevant parameter of the SR
machine 106.
[0023] Once the mutual flux value is obtained, the controller 128
may be configured to determine the decoupled flux value by direct
computation or by reference to predefined models or relationships
programmed in memory 130. In one embodiment for instance, the
controller 128 may be configured to compute the decoupled flux
value by subtracting the mutual flux value from the total flux
value. In alternative embodiments, the controller 128 may be
configured to lookup the appropriate decoupled flux value from
predefined lookup tables, maps, or the like, that are stored in
memory 130 and adapted to indicate appropriate decoupled flux
values for different combinations of total flux and mutual flux
values. Based on the decoupled flux value for given idle phases of
the SR machine 106, the controller 128 may further be configured to
determine the position of the rotor 110 relative to the stator 112
in block 132-5. More particularly, the controller 128 may directly
compute, or alternatively, access one or more predefined models,
such as lookup tables, maps, or the like, that are preprogrammed in
memory 130 and interpolate different rotor positions for different
machine states. For example, the predefined models may be able to
indicate the rotor position based on a given phase current,
decoupled flux value, or the like.
[0024] Once rotor position is obtained, the controller 128 may
optionally or additionally be configured to derive the speed and/or
direction of the rotor 110 relative to the stator 112, in
accordance with optional block 132-6 of the method 132 of FIG. 2.
In still further modifications, the controller 128 may be
configured to determine or compute other parameters pertaining to
the SR machine 106 which may be derived based on the rotor
position. Furthermore, in block 132-7 of the method 132 of FIG. 2,
the controller 128 may be configured to control the converter
circuit 116, or the switches 120 thereof, and operate the phases of
the SR machine 106 in accordance with the rotor position
information and/or any additional information derived therefrom.
Once appropriate controls or adjustments to the SR machine 106 have
been made, the controller 128 may continue or return to any of the
blocks in the method 132 shown and repeat any one or more of the
processes as needed.
[0025] Turning to FIG. 3, one exemplary embodiment of a control
scheme 134 for operating an SR machine 106 is shown in diagrammatic
form. More particularly, the control scheme 134 may be implemented
on the controller 128 and configured to at least determine the
position of the rotor 110 relative to the stator 112 of the SR
machine 106 in accordance with the method 132 of FIG. 2 for
instance. As shown, the control scheme 134 may include a
measurement module 136 that is configured to monitor at least the
phase current within the SR machine 106, or at least the current
through each idle phase, and communicate data corresponding to the
measured phase current as needed by any one or more of a plurality
of computations being performed by the controller 128. The control
scheme 134 may also include a feedback loop 138 which provides data
pertaining to the last known or most recently determined rotor
position, or rotor position feedback data, to be referenced during
any one or more of the computations by the controller 128.
[0026] In accordance with block 132-2 of the method 132 of FIG. 2
for instance, the control scheme 134 may further implement a pulse
injection module 138 adapted to inject a diagnostic or test pulse
of voltage into the relevant phases of the SR machine 106.
Specifically, the pulse injection module 138 may be configured to
inject a test pulse with a substantially constant current height
through at least each idle or non-controlling phase of the stator
112. The test pulse, such as the duration, magnitude and
consistency of the injected signal, may be configured at least
partially based on the measured phase current provided by the
measurement module 136 and the rotor position feedback data
provided by the feedback loop 138. The injected test pulse signal
may then be communicated to an integrator module 142 which
integrates the test pulse voltage to calculate the corresponding
total flux value induced in the idle phases of the SR machine 106,
for example, in accordance with block 132-3 of the method 132 of
FIG. 2.
[0027] Once the total flux value has been obtained, the control
scheme 134 may be configured to determine the self-induced or
decoupled flux value corresponding to the idle phases from the
total flux value as in block 132-4 of the method 132 of FIG. 2.
More specifically, because the total flux value is the sum of the
decoupled flux value and the mutual flux value, or flux due to
mutual coupling for a given set of idle phases of the SR machine
106, the control scheme 134 may be able to obtain the decoupled
flux value based on a difference between the total flux value and
the mutual flux value. For example, the control scheme 134 may
employ an adder 144, or the like, to subtract out the mutual flux
value from the total flux value and isolate the decoupled flux
value. To determine the mutual flux, the control scheme 134 may
refer to a mutual flux model 146 which outputs or estimates the
mutual flux value based on the operating state of the SR machine
106. For example, the mutual flux model 146 may provide one or more
preprogrammed lookup tables, maps, or the like, which correlate
different mutual flux values for different possible combinations of
phase current and rotor position. Using such predefined models, the
control scheme 134 may be able to determine the mutual flux value
based on the phase current as measured by the measurement module
136 and the rotor position as provided by the feedback loop
138.
[0028] Based on the decoupled flux value determined for a given set
of idle phases, the control scheme 134 may employ a decoupled flux
model 148 to determine the corresponding rotor position in
accordance with block 132-5 of the method 132 of FIG. 2 for
example. The decoupled flux model 148 may employ one or more lookup
tables, maps, or the like, which are preprogrammed according to
known relationships between rotor position, phase current, and
decoupled or self-induced flux values best suited for standstill or
low speed operations of the SR machine 106. More specifically,
based on the computed decoupled flux value and the phase current as
measured by the measurement module 136, the decoupled flux model
148 may be able to output a reliable estimate of the current rotor
position. In accordance with block 132-6 of the method 132 of FIG.
2, the control scheme 134 may further provide an output module 150
to perform any additional computations on the determined rotor
position. For example, the output module 150 may be configured to
derive the rotor speed and/or direction to further aid in the
control of the converter circuit 116 and/or the SR machine 106. The
rotor position data may also be fed back into the control scheme
134 by the feedback loop 138 for further iterations.
INDUSTRIAL APPLICABILITY
[0029] In general, the foregoing disclosure finds utility in
various applications relating to switched reluctance (SR) machines
or any other suitable electric machine being employed as motors
and/or generators. In particular, the disclosed systems and methods
may be used to provide more efficient control of SR machines that
are typically employed in association with the electric drives of
power generation machines, industrial work vehicles, and other
types of machines commonly used in the art. The present disclosure
may also be implemented with other variable-speed drives commonly
used in association with industrial and consumer product
applications. The present disclosure may further be used with
integrated starters, generators, or the like, commonly associated
with automotive, aerospace, and other comparable mobile
applications.
[0030] More specifically, the present disclosure provides a means
for operating an SR machine during standstill and low speed
operations which does not rely on complex and costly rotor position
sensors to provide reliable rotor position feedback. In particular,
the systems and methods disclosed herein provide more accurate,
cost-effective and sensorless means for determining rotor position
to enable more efficient operation of SR machines. The present
disclosure thereby also enables implementation of SR machines and
associated electric drives in applications where use of rotor
position sensors was otherwise not practical.
[0031] From the foregoing, it will be appreciated that while only
certain embodiments have been set forth for the purposes of
illustration, alternatives and modifications will be apparent from
the above description to those skilled in the art. These and other
alternatives are considered equivalents and within the spirit and
scope of this disclosure and the appended claims.
* * * * *