CLIAMS:1. An engine system, comprising:
a first fluid regulation component;
a second fluid regulation component interrelated to the first fluid regulation component;
a processing subsystem that:
determines a plurality of interaction gain matrices based upon a plurality of transfer functions, that define the dynamics of the engine system, and one or more operational data values;
determines a decoupling matrix, comprising a plurality of decoupling values, and a plurality of control gain parameters by solving an objective function generated based upon the plurality of interaction gain matrices, subject to satisfaction of one or more performance constraints associated with the engine system; and
decoupling the first fluid regulation component and the second fluid regulation component based upon the plurality of decoupling values and the plurality of control gain parameters to achieve emissions of the engine system within desired emission limits.

2. The engine system of claim 1, wherein the processing subsystem determines the decoupling matrix and the plurality of control gain parameters for a plurality of operating conditions and a plurality of operating frequencies of the engine system.

3. The engine system of claim 1, further comprising generating the objective function based upon a principle that a multiplication of the decoupling matrix and an interaction gain matrix in the plurality of interaction gain matrices is an identity matrix.

4. The engine system of claim 1, wherein the objective function comprises the plurality of decoupling values as decision variables.

5. The engine system of claim 1, further comprising:
a plurality of cylinders that generate recirculation exhaust gas and non-recirculation exhaust gas;
an intake manifold to at least receive a desired amount of a first fraction of the recirculation exhaust gas; and
an exhaust manifold that receives emission exhaust gas that is a mixture of a second fraction of the recirculation exhaust gas and the non-recirculation exhaust gas.

6. The engine system of claim 1, wherein the processing subsystem further generates the plurality of transfer functions using a lineralization technique, a real-time system identification technique, or a combination thereof.

7. The engine system of claim 6, wherein the processing subsystem further generates the plurality of transfer functions based upon an engine dynamics model, or data received from the engine system.
8. The engine system of claim 1, wherein the plurality of transfer functions comprises different transfer functions for different operating conditions of the engine system.

9. The engine system of claim 1, wherein the processing subsystem determines the plurality of interaction gain matrices corresponding to a plurality of operating frequencies of the engine system.

10. The engine system of claim 1, wherein the processing subsystem comprises a dynamic controller.

11. The engine system of claim 10, wherein the plurality of transfer functions are mathematical representations used by the dynamic controller to achieve desired outputs.

12. The engine system of claim 1, further comprising generating the plurality of transfer functions based upon one or more operational data variables associated with the engine system.

13. The engine system of claim 11, wherein the one or more operational data variables comprise pressure, temperature, oxygen fraction, settings of the first fluid regulation component, settings of the second fluid regulation component, flow rates, speed, or other parameters associated with one or more components of the engine system.
14. The engine system of claim 1, wherein the processing subsystem solves the objective functions using one or more techniques comprising a simulated annealing technique, a surrogate-based optimization technique, an interior point technique, an active set technique, a sequential programming technique, a linear programming technique, a quadratic programming technique, a convex programming technique, a nonlinear programming technique, a robust optimization technique, a stochastic optimization technique, or combinations thereof.

15. The engine system of claim 1, wherein the one or more performance constraints comprises overshoot time, overshoot percentage, rise time, decay ratio, settling time, undershoot time, undershoot percentage, integral square error, integral absolute error, or combinations thereof.

16. The engine system of claim 1, wherein the one or more performance constraints comprises the plurality of control gain parameters and the decoupling values as decision variables.

17. The engine system of claim 3, wherein the one or more performance constraint comprises a condition that a maximum overshoot time of the first portion of the recirculation exhaust gas is less than a determined time period.

18. An engine system, comprising:
a first fluid regulation component;
a second fluid regulation component interrelated to the first fluid regulation component;
a processing subsystem that:
determines a plurality of interaction gain matrices based upon a plurality of transfer functions that define the dynamics of the engine system, and one or more operational data values;
generates an objective function, comprising a plurality of decoupling values as decision variables, based upon the plurality of interaction gain matrices; and
determines one or more performance constraints, to solve the objective function subject to the satisfaction of the one or more performance constraints, based upon efficiency required from the engine system and configuration of the engine system.

19. The engine system of claim 18, wherein the processing subsystem generates the objective function based upon the principle that that a multiplication of the decoupling matrix and an interaction gain matrix in the plurality of interaction gain matrices is an identity matrix.

20. A method for decoupling two or more fluid regulation components that are interrelated, comprising:
determining a plurality of interaction gain matrices based upon a plurality of transfer functions, that define the dynamics of an engine system, and one or more operational data values;
determining a decoupling matrix, comprising a plurality of decoupling values, and a plurality of control gain parameters by solving an objective function generated based upon the plurality of interaction gain matrices, subject to satisfaction of one or more performance constraints associated with the engine system; and
decoupling the first fluid regulation component and the second fluid regulation component based upon the plurality of decoupling values and the control gain parameters to achieve emissions of the engine system within desired emission limits.
,TagSPECI:BACKGROUND
[0001] An engine system generally comprises a turbocharger. A
turbocharger typically includes a compressor that is rotationally coupled to a
turbine via a shaft. Typically when a turbocharger is used with a combustion
engine, the turbine of the turbocharger is disposed in the path of exhaust gas
exiting the combustion engine. The turbine includes a wheel (hereinafter:
‘turbine wheel’) that is rotated by the flow of the exhaust gas. The turbine wheel
is rotatably coupled to a wheel (hereinafter: ‘compressor wheel’) of a compressor,
in the turbocharger. The compressor is disposed in-line with an air-intake system
of the combustion engine. Rotation of the turbine by the exhaust gas flow causes
the compressor wheel to likewise rotate, wherein rotation of the compressor
wheel acts to increase the flow of fresh air into an air intake system. One or more
combustion cylinders in the combustion engine receive the fresh air from the air
intake system and fuel from a fuel source to generate an air-fuel mixture. The
combustion cylinders combust the air-fuel mixture to generate energy and
exhaust gas. In some internal combustion engines, a portion of exhaust gas
generated by the internal combustion engines is recirculated within the internal
combustion engines to mix the portion of the exhaust gas and an air-fuel mixture
resulting in generation of air-exhaust-gas-fuel mixture. Combustion cylinders in
the internal combustion engines combust the air-exhaust-gas-fuel mixture to
generate energy and the exhaust gas.
[0002] Typically engines, including internal combustion engines, include
fluid regulation components controlled to regulate an amount of the fresh air and
the portion of the exhaust gas that is mixed with the fuel to generate the airexhaust-
gas-fuel mixture. For example, a valve A may be controlled to regulate
an amount of the fresh air that is mixed with the portion of the exhaust gas and
the fuel. Similarly, a valve B may be controlled to regulate an amount of the
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portion of the exhaust gas that is mixed with the air and fuel. Although, the fluid
regulation components are independently controlled to choose independent
settings of the fluid regulation components, however the effects of the
independent settings of the fluid regulation components are interrelated. For
example, a valve A may be independently controlled to mix a desired amount of
the fresh air with the portion of the exhaust gas and fuel, and a valve B may be
independently controlled to mix a desired amount of the portion of the exhaust
gas with the fresh air. However, the control of the valve A not only directly
impacts the amount of the fresh air that is mixed with the portion of the exhaust
gas, but also indirectly impacts the concentration of the portion of the exhaust gas
in a mixture of the fresh air, the exhaust gas. Similarly, the control of the valve B
not only directly impacts the amount of the exhaust gas that is mixed with fresh
air and the fuel, but also impacts the concentration of air in the mixture of air,
exhaust gas and fuel.
[0003] Therefore, the fluid regulation components are interrelated such
that a change in settings of one fluid regulation component not only impacts
effects corresponding to the fluid regulation component but also impacts other
effects corresponding to another fluid regulation component. Such
interrelationship of fluid regulation components result in instability in fluid
regulation mechanisms of engines. Furthermore, such interrelationship between
fluid regulation components may not allow achieving desired performance
objectives of the engines.
[0004] Therefore, it would be advantageous to provide improved systems
and methods to decouple fluid regulation components that are interrelated to
achieve desired performance objectives of systems that contain the fluid
regulation components.
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BRIEF DESCRIPTION
[0005] In accordance with one embodiment, an engine system is
presented. The engine system includes a first fluid regulation component, a
second fluid regulation component interrelated to the first fluid regulation
component, a processing subsystem that determines a plurality of interaction gain
matrices based upon a plurality of transfer functions, that define the dynamics of
the engine system, and one or more operational data values, determines a
decoupling matrix, comprising a plurality of decoupling values, and a plurality of
control gain parameters by solving an objective function generated based upon
the plurality of interaction gain matrices, subject to satisfaction of one or more
performance constraints associated with the engine system, and decoupling
the first fluid regulation component and the second fluid regulation component
based upon the plurality of decoupling values and the plurality of control gain
parameters to achieve emissions of the engine system within desired emission
limits.
[0006] In accordance with another embodiment an engine system is
presented. The engine system includes a first fluid regulation component, a
second fluid regulation component interrelated to the first fluid regulation
component, a processing subsystem that determines a plurality of interaction gain
matrices based upon a plurality of transfer functions that define the dynamics of
the engine system, and one or more operational data values, generates an
objective function, comprising a plurality of decoupling values as decision
variables, based upon the plurality of interaction gain matrices, and determines
one or more performance constraints, to solve the objective function subject to
the satisfaction of the one or more performance constraints, based upon efficiency
required from the engine system and configuration of the engine system.
[0007] In accordance with yet another embodiment a method for
decoupling two or more fluid regulation components that are interrelated is
presented. The method, includes the steps of determining a plurality of
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interaction gain matrices based upon a plurality of transfer functions, that define
the dynamics of an engine system, and one or more operational data values,
determining a decoupling matrix, comprising a plurality of decoupling values,
and a plurality of control gain parameters by solving an objective function
generated based upon the plurality of interaction gain matrices, subject to
satisfaction of one or more performance constraints associated with the engine
system, and decoupling the first fluid regulation component and the second fluid
regulation component based upon the plurality of decoupling values and the
control gain parameters to achieve emissions of the engine system within desired
emission limits.
DRAWINGS
[0008] These and other features and aspects of embodiments of the
present invention will become better understood when the following detailed
description is read with reference to the accompanying drawings in which like
characters represent like parts throughout the drawings, wherein:
[0009] FIG. 1 is a block diagram of a system to analyze a gas-mixture, in
accordance with one embodiment of the present systems; and
[0010] Fig. 2 is a flow chart illustrating an exemplary method for
decoupling two or more fluid regulation components that are interrelated to
achieve emissions within desired limits from an engine, in accordance with one
embodiment of the present techniques.
DETAILED DESCRIPTION
[0011] The present systems and methods, described in detail hereinafter,
regulate and control a plurality of fluid regulation components that are
interrelated. Particularly, the present systems and methods decouple the fluid
regulation components. In one embodiment, when the fluid regulation
components are mechanisms/devices of a locomotive engine, the present systems
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and methods decouple the fluid regulation components to achieve emissions
within desired limits from the locomotive engine. For example, the present
systems and methods decouple the fluid regulation components to achieve nitrous
oxide emissions (NOx), and formation of particulate matter (PM) within desired
limits. In one embodiment, the present systems and methods achieve the
emissions in consistence emission requirements of internal combustion engines.
The fluid regulation components, for example, may be valves, a variable
geometry turbine (VGT), or the like.
[0012] As used herein, the term “fluid regulation component’ is a device
or a component that regulates an amount of fluid passing through the device, or
the component, or impacts pressures/flows downstream, or combinations thereof.
As used herein, the term “interrelated” is used to refer to an interdependency of a
first fluid regulation component and a second fluid regulation component, such
that a variation in an input/control/opening/settings of the first fluid regulation
component not only impacts effects associated with the first fluid regulation
component but also impacts effects associated with the second fluid regulation
component, and vice versa. It is noted that while, for ease of understanding, the
definition of “interrelated” is defined with reference to two fluid regulation
components, including a first fluid regulation component and a second fluid
regulation component, however more than two fluid regulation components may
be interrelated to each other. As used herein, the phrase “decoupling the first
fluid regulation component and the second fluid regulation component” refers to
adjusting an amount of opening of the first fluid regulation component to
normalize for the effects or impact of the second fluid regulation component on
an output/ultimate impact of the first fluid regulation component, and/or adjusting
an amount of opening of the second fluid regulation component to normalize for
the effects or impact of the first fluid regulation component on an output/ultimate
impact of the second fluid regulation component.
[0013] The present systems and methods described herein may be
employed in a variety of engine types, and a variety of engine-driven systems.
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Some of these engine-driven systems may be stationary, while others may be on
semi-mobile or mobile platforms. Semi-mobile platforms may be relocated
between operational periods, such as mounted on flatbed trailers. Mobile
platforms include self-propelled vehicles. Such self-propelled vehicles can
include mining equipment, marine vessels, on-road transportation vehicles, offhighway
vehicles (OHV), and rail vehicles. For clarity of illustration, a Tier 4
locomotive engine is discussed in Fig. 1.
[0014] Referring now to FIG. 1, a block diagram of an engine system 100
is shown, in accordance with certain embodiments of the present techniques. The
engine system 100 includes an engine 101, an engine control unit 150 and a data
repository 152. However, the present systems and techniques should not be
restricted to the design and configuration of the engine 101 shown in Fig. 1. In
one embodiment, the engine 101 includes a plurality of cylinders 102, 104 and an
intake manifold 106. In the presently contemplated configuration, the plurality of
cylinders 102, 104 includes a plurality of donor cylinders 102 and a plurality of
non-donor cylinders 104. It is noted that while the present systems and
techniques are explained with reference to the donor cylinders 102 and the nondonor
cylinders 104, the present systems and techniques may be applied to
engines that do not have the donor cylinders 102 and the non-donor cylinders
104, and do not differentiate between cylinders as the donor cylinders 102 and
the non-donor cylinders 104. The donor cylinders 102 and the non-donor
cylinders 104 are operationally coupled to the intake manifold 106. The donor
cylinders 102 and the non-donor cylinders 104 receive air-exhaust-gas mixture
108 from the intake manifold 106, and fuel from a fuel source (not shown)
resulting in formation of air-exhaust-gas-fuel mixture (not shown). The airexhaust-
gas-fuel mixture is combusted in the donor cylinders 102 and the nondonor
cylinders 104 to generate energy and exhaust gas 110, 112. The first
portion 110 of the exhaust gas 110, 112 is generated by the donor cylinders 102,
and the second portion 112 of the exhaust gas 110, 112 is generated by the nondonor
cylinders 104. A portion or whole of the first portion 110 may be
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recirculated within the engine 101. The non-donor cylinders 112 are operationally
coupled to an exhaust manifold 124. The exhaust manifold 124 receives the
second portion of the exhaust gas 114 from the non-donor cylinders 104. For
ease of understanding, the first portion 110 shall be referred to as “recirculation
exhaust gas 110” and the second portion 112 shall be referred to as “nonrecirculation
exhaust gas 112”.
[0015] The donor cylinders 102 are operationally coupled to an exhaust
gas recirculation manifold 118 (hereinafter ‘EGR manifold’). The EGR manifold
118 receives the recirculation exhaust gas 110 generated by the donor cylinders
102. The EGR manifold 118 is operationally coupled to the intake manifold 106
via a first fluid regulation component 120. The first fluid regulation component
120 regulates an amount or a first fraction 121 of the recirculation exhaust gas
110 that is directed into the intake manifold 106. The first fraction 121 of the
recirculation exhaust gas 110 directed into the intake manifold 106 shall
hereinafter be referred to by the phrase ‘recirculated exhaust gas 121’. In the
presently contemplated configuration, the recirculated exhaust gas 121 is cooled
by a first heat exchange mechanism 127 before the recirculated exhaust gas 121
is directed into the intake manifold 106.
[0016] Additionally, the EGR manifold 118 is operationally coupled to an
exhaust manifold 124 via a valve 122. The valve 122 regulates an amount of a
second fraction 111 of the recirculation exhaust gas 110 that is directed into the
exhaust manifold 124 from the EGR manifold 118. Furthermore, as previously
noted, the non-donor cylinders 104 are operationally coupled to the exhaust
manifold 124 to enable direction of the non-recirculation exhaust gas 112 into the
exhaust manifold 124. Accordingly, the non-recirculation exhaust gas 112
generated by the non-donor cylinders 104 is directed into the exhaust manifold
124 from the non-donor cylinders 104. In view of the above, the exhaust
manifold 124 receives the second fraction 111 of the recirculation exhaust gas
110 and the non-recirculation exhaust gas 112 to form a mixture of the second
fraction 111 of the recirculation exhaust gas 110 and the non-recirculation
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exhaust gas 112. Hereinafter, the mixture of the non-recirculation exhaust gas
112 and the second fraction 111 of the recirculation exhaust gas 110 shall be
referred to as emission exhaust gas 113. The emissions exhaust gas 113 is used
to run the one or more turbochargers 114, 116. After running the one or more
turbochargers 114, 116, the second portion 112 is treated by an after treatment
system (not shown) to generate treated-exhaust-gas (not shown), and the treatedexhaust-
gas is vented out of the engine 101.
[0017] It is noted that while the presently contemplated configuration
describes the present systems and techniques with reference to the engine 101
that includes the one or more turbochargers 114, 116, the present systems and
techniques may be applied in engines that do not use turbochargers. The
turbocharger 114 includes a high pressure turbine 126 and a high pressure
compressor 128. Furthermore, the turbocharger 116 includes a low pressure
turbine 130 and a low pressure compressor 132. While the presently
contemplated configuration shows the two turbochargers 114, 116, a number of
turbocharges in the engine 101 may be more or less than two.
[0018] The one or more compressors 128, 132 in the one or more
turbochargers 114, 116 suck fresh air 134 from the environment and compress the
fresh air 134 to increase the pressure of the fresh air 134 to generate pressurized
air 136 that enters the intake manifold 106. In the presently contemplated
configuration, the low pressure compressor 132 sucks the fresh air 134 from the
environment, and increases the pressure of the fresh air 134 to generate first level
pressurized air 138; and a second heat exchange mechanism 140 cools the first
level pressurized air 138 to generate cooled first level pressurized air 142. The
high pressure compressor 128 receives the cooled first level pressurized air 142
and compresses the cooled first level pressurized air 142 to generate second level
pressurized air 144. The second level pressurized air 144 is cooled in a third heat
exchange mechanism 146 to generate the pressurized air 136. The increase in the
pressure of the fresh air 134, to generate the pressurized air 136, achieves a
desired density of the pressurized air 136 in the intake manifold 106. It is noted
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that the present systems and techniques may be applied irrespective of the
presence or absence of the first heat exchange mechanism 127, the second heat
exchange mechanism 140, and the third heat exchange mechanism 146.
[0019] The pressurized air 136 is received by the intake manifold 106.
Furthermore, as previously noted, based upon the percentage opening of the first
fluid regulation component 120, the intake manifold 106 receives the recirculated
exhaust gas 121. The receipt of the pressurized air 136 and the recirculated
exhaust gas 121 results in formation of the air-exhaust gas mixture 108 in the
intake manifold 106. The air-exhaust gas mixture 108 and the fuel are received
by the donor cylinders 102 and the non-donor cylinders 104 resulting in
formation of air-exhaust-gas-fuel mixture. As previously noted, the air-exhaustgas-
fuel mixture is combusted in the donor cylinders 102 and the non-donor
cylinders 104 to generate energy and the exhaust gas 110, 112.
[0020] The exhaust manifold 124 is operationally coupled to the high
pressure turbine 126 of the turbocharger 114. Furthermore, the exhaust manifold
124 is operationally coupled to the low pressure turbine 130 of the turbocharger
116 via a second fluid regulation component 148. The emission exhaust gas 113
is directed towards the high pressure turbine 126 and the low pressure turbine
130. The direction of the emission exhaust gas 113 rotates the high pressure
turbine 126 and the low pressure turbine 130. Since the high pressure turbine 126
is rotatably connected to the high pressure compressor 128 and the low pressure
turbine 130 is rotatably coupled to the low pressure compressor 132; the rotation
of the high pressure turbine 128 rotates the high pressure compressor 128, and the
rotation of the low pressure turbine 130 rotates the low pressure compressor 132.
Rotation of the high pressure compressor 128 and the low pressure compressor
132 sucks the fresh air 134 from the environment. Higher the speed of the high
pressure turbine 126 and the low pressure turbine 130, higher is the speed of the
high pressure compressor 128 and the low pressure compressor 132. Higher the
speed of the high pressure compressor 128 and the low pressure compressor 132,
higher amount of the fresh air 134 is sucked by the high pressure compressor 128
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and the low pressure compressor 132, and higher is the pressure of the airexhaust
gas mixture 108 in the intake manifold 106. The pressure of the airexhaust
gas mixture 108 in the intake manifold 106 is referred to as boost
pressure. The second fluid regulation component 148 is controlled to distribute
the emission exhaust gas 113 between the high pressure turbine 126 and the low
pressure turbine 130 to achieve desired boost pressure in the intake manifold 106.
For example, the second fluid regulation component 148 may be controlled to
enable a fraction of the emission exhaust gas 113 bypass the high pressure turbine
126 to reduce the speed of the high pressure turbine 128 and therefore reduce the
boost pressure. In other words, the second fluid regulation component 148 may
be controlled or regulated to increase or decrease the speed of the high pressure
turbine 148 which leads to increase or decrease in the boost pressure in the intake
manifold 106.
[0021] Accordingly, the second fluid regulation component 148 may be
controlled to increase or decrease the boost pressure in the intake manifold 106. .
The increase or decrease in the boost pressure in the intake manifold 106 may
impact the flow rate of the recirculated exhaust gas 121 in the intake manifold
106. Accordingly, changes in settings of the second fluid regulation component
148 not only directly impacts the boost pressure in the intake manifold 106, but
also indirectly impacts the amount of the recirculated exhaust gas 121 in the
intake manifold which is controlled by the first fluid regulation component 120.
[0022] Similarly, as previously noted, the first fluid regulation component
120 may be controlled to increase or decrease the amount the recirculated exhaust
gas 121 in the intake manifold 106. In other words, the first fluid regulation
component 120 may be controlled (settings may be changed) to increase or
decrease the recirculated exhaust gas 121 fraction and oxygen fraction in the
intake manifold 106. The control of the first fluid regulation component 120, for
example, includes changing the settings of the first fluid regulation component
120 or changing the percentage opening of the first fluid regulation component
120. The changes in the settings of the first fluid regulation component 120 not
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only impacts the amount of the recirculated exhaust gas 121 and oxygen fraction
in the intake manifold 106, but also indirectly impacts the boost pressure which is
controlled by the second fluid regulation component 148. Accordingly, in the
presently contemplated configuration, the first fluid regulation component 120
and the second fluid regulation component 148 are interrelated.
[0023] The boost pressure and the amount of the recirculated exhaust gas
121 directly or indirectly impact emissions, such as particulate matter and NOx
emissions of the engine 101. Accordingly, the first fluid regulation component
120 and the second fluid regulation component 148 may be controlled to achieve
desired outputs, such as, desired boost pressure and desired amount of the
recirculated exhaust gas 121 resulting in achievement of the emissions within
desired limits. However, the interrelationship of the first fluid regulation
component 120 and the second fluid regulation component 148 hampers an
effective control of the first fluid regulation component 120 and the second fluid
regulation component 148. Accordingly, decoupling of the first fluid regulation
component 120 and the second fluid regulation component 148 is desired to
achieve emissions, of the engine 101, within desired limits.
[0024] The present engine system 100 includes the engine control unit
150 operationally coupled to the engine 101 and the data repository 152. In the
presently contemplated configuration, the engine control unit 150 decouples the
first fluid regulation component 120 and the second fluid regulation component
148 to achieve desired emission levels of the engine 101. Particularly, the engine
control unit 150 decouples the first fluid regulation component 120 and the
second fluid regulation component 148 to achieve desired outputs, such as,
desired amount of the recirculated exhaust gas 121 or desired oxygen fraction in
the intake manifold 106 by taking into account the impact of the settings of the
second fluid regulation component 148; or desired boost pressure in the intake
manifold 106 by taking into account the impact of the settings of the first fluid
regulation component 120. The engine control unit 150 achieves the desired
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emission level of the NOx and particulate matter by decoupling the first fluid
regulation component 120 and the second fluid regulation component 148.
[0025] The engine control unit 150, for example, may be one or more
processing subsystems, microprocessors, or the like that communicate on a wired
or wireless medium with the engine 101. In one embodiment, the engine control
unit 150 comprises a dynamic controller 151. The dynamic controller 151, for
example, may be a proportional-integral-derivative controller, a proportional
controller, proportional integral controller, proportional derivative controller, a
lag compensator, a lead compensator, a lag-lead compensator, a static decoupler,
or the like. It is noted the engine control unit 150 performs many other functions
apart from the functions described with reference to the present systems and
methods.
[0026] The engine control unit 150 receives a plurality of transfer
functions from the data repository 152. The transfer functions are mathematical
representations, in terms of spatial or temporal frequency, used by the dynamic
controller 151 to achieve desired outputs for inputs. The transfer functions define
relationship between the desired outputs and the inputs of the engine 101. The
transfer functions are formulated using operational data variables associated with
the engine 101 or the engine system 100. It is noted that different transfer
functions may exist for different operating conditions of the engine 101. For
example, the operating conditions may include a steady state, a transient state, a
full load state, a zero load state, load in-between zero load and full load, or the
like. The transfer functions will be explained in greater detail in Fig. 2.
[0027] The engine control unit 150 receives operational data values
corresponding to the engine 101 from the engine 101. As used herein, the term
“operational data values” refers to numerical values of the operational data
variables that are used to formulate the transfer functions. The operational data
variables, for example may include pressure, temperature, oxygen fraction,
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settings of fluid regulation component, flow rates, speed, or other parameters
associated with one or more components of the engine system 100.
[0028] The engine control unit 150 determines a plurality of interaction
gain matrices at least based upon the operational data values and the transfer
functions. The determination of the interaction gain matrices is explained in
greater detail with reference to Fig. 2. The engine control unit 150 determines
the plurality of interaction gain matrices corresponding to a plurality of operating
frequencies of the engine. In one embodiment, the engine control unit determines
a single interaction matrix corresponding to a single operating frequency of the
engine 101.
[0029] Furthermore, the engine control unit 150 determines one or more
decoupling values and control gain parameters by solving an objective function,
subject to satisfaction of the performance constraints, based upon the interaction
gain matrices. The objective function and the performance constraints are
explained in greater detail with reference to Fig. 2. Furthermore, the engine
control unit 150 controls the first fluid regulation component 120 and the second
fluid regulation component 148 based upon the decoupling values and the control
gain parameters. As used herein, the term “decoupling values” are used to refer
to constant values that are used to decouple two or more interrelated fluid
regulation components. As used herein, the term “control gain parameters” is
used to refer to one or more of a proportional constant, an integral constant and a
derivative constant used by dynamic controllers. Particularly, the engine control
unit 150 decouples the first fluid regulation component 120 and the second fluid
regulation component 148 based upon the decoupling values and the control gain
parameters to achieve emissions within desired limits from the engine 101. The
usage of the decoupling values and the control gain parameters to decouple the
first fluid regulation component 120 and the second fluid regulation component
148 are explained in greater detail with reference to Fig. 2.
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[0030] Fig. 2 is a flow chart 200 illustrating an exemplary method for
decoupling two or more fluid regulation components that are interrelated to
achieve emissions within desired limits from an engine, such as, the engine 101,
in accordance with one embodiment of the present techniques. In the presently
contemplated configuration, the exemplary method generates a decoupling matrix
comprising decoupling values and a plurality of control gain parameters. The
decoupling values and the control gain parameters are used to decouple the first
fluid regulation component 120 and the second fluid regulation component 148
referred to in Fig. 1. It is noted that while the present techniques are explained
with reference to the engine 101, the first fluid regulation component 120 and the
second fluid regulation component 148, however the present techniques may be
employed for decoupling any two or more fluid regulation components.
[0031] Block 202 is representative of a plurality of transfer functions that
define the dynamics of the engine 101 to achieve desired outputs for given inputs.
The transfer functions 202, for example are a set of programmable instructions
that are used by a processor. The transfer functions may be generated using an
engine dynamics model, or using data or the operational data variables received
from the engine 101. For example, the transfer functions may be generated using
a linearization technique, or a real-time system identification technique. It is
noted that the transfer functions may vary from one engine to another based upon
the configuration, design and operating condition of the engine.
[0032] The transfer functions 202, for example, are generated using a
plurality of operational data variables associated with the engine 101. The
operational data variables, for example, may be pressure, temperature, oxygen
fraction, valve positions, flow rates, speed, or other parameters associated with
one or more components of the engine 101. The desired outputs of the transfer
functions 202, for example, may be boost pressure, recirculation exhaust gas flow
in the intake manifold 106, oxygen fraction in the intake manifold 106, peak
cylinder pressure in the cylinders 102, 104, one or more of the operational data
variables which impact emissions and performance of the engine 101, or the like.
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The inputs of the transfer functions 202, for example, may be the percentage
opening of the first fluid regulation component 120 and the percentage opening
of the second fluid regulation component 148. For example, four transfer
functions including G11, G12, G21 and G22 correspond to an operating condition of
the engine 101. The transfer functions G11, G12, G21 and G22 may be related to a
percentage opening of the first fluid regulation component 120, a percentage
opening of the second fluid regulation component 148, the amount of the
recirculated exhaust gas 121 and the boost pressure referred to in Fig. 1 as
follows:
(% ) (% ) 21 22 MAP= FFRC*G + SFRC*G (1)
(% ) (% ) 11 12 EGR= FFRC*G + SFRC*G (2)
wherein %FFRC is representative of a percentage opening of the first fluid
regulation component 120, %SFRC is representative of the second fluid
regulation component 148, MAP is representative of boost pressure, and EGR is
representative of the amount of recirculated exhaust gas 121 directed into the
intake manifold 106.
[0033] Reference numeral 204 is representative of a plurality of
operational data values. The operational data values 204 are numerical values of
the operational data variables associated with the engine 101. The operational
data values are collected/received/generated for a time period T during the
operation of the engine 101. At block 206, a plurality of interaction gain matrices
is determined based upon the transfer functions 202 and the operational data
values 204. The interaction gain matrices, for example, may correspond to
different operating conditions of the engine 101. In one embodiment, a single
interaction gain matrix is determined for a determined operating condition of the
engine 101. For example, a single interaction gain matrix is determined for a
steady state condition. The engine control unit 150 may determine the interaction
gain matrices corresponding to a plurality of operating frequencies of the engine
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17
101. In one embodiment, an interaction gain matrix may be determined
corresponding to an operating frequency that is equal to 0 radian/second, 2
radian/second, or the like.
[0034] The operational data values 204 are substituted in the transfer
functions 202 to generate the interaction gain matrices. For example, operational
data values generated, at a determined operating condition, may be substituted in
the transfer functions G11, G12, G21, G22 to generate an interaction gain matrix.
For example, a first transfer function value DC(1,1) may be generated by
substituting one or more of the operational data values 204, at a determined
operating condition, in the transfer function G11. Similarly, a second transfer
function value DC(1,2) may be generated by substituting one or more of the
operational data values 204 in the transfer function G12. Again, a third transfer
function value DC(2,1) may be generated by substituting one or more of the
operational data values 204 in the transfer function G21. Furthermore, a fourth
transfer function value DC(2,2) may be generated by substituting one or more of
the operational data values 204 in the transfer function G22. An interaction gain
matrix A1 may be generated using the first transfer function value DC(1,1), the
second transfer function value DC(1,2), the third transfer function value DC(2,1),
and the fourth transfer function value DC(2,2).
[0035] The interaction gain matrix A1 may be represented as follows:
??
?
??
?
=
(2,1) (2,2)
(1,1) (1,2)
1 DC DC
DC DC
A (3)
[0036] At blocks 208 and 210 an optimization problem is formulated and
solved to determine a decoupling matrix and control gain parameters. In the
presently contemplated configuration, at block 208, an objective function may be
generated based upon the transfer functions 202 and the operational data values
204. Particularly, the objective function is generated based upon the interaction
gain matrices. The objective function comprises the decoupling values and
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18
control gain parameters as decision variables. The objective function is generated
based upon a principle that a multiplication of the decoupling matrix and an
interaction gain matrix in the plurality of interaction gain matrices is an identity
matrix (I). For example, when A1 is the interaction gain matrix and W is a
decoupling matrix comprising the objective function is generated based upon the
following principle:
A1 * W = I (4)
[0037] The decoupling matrix W is represented as follows:
??
?
??
?
=
21 22
11 12
W W
W W
W (5)
wherein W11, W12, W21, and W22 are decoupling values.
[0038] In accordance with one embodiment of the present techniques,
when the interaction gain matrix A1 is represented as shown in equation (3), and
the decoupling matrix W is represented as shown in equation (5), and n is an
operating condition, then the objective function may be represented by the
following equation (6):
min . . 2 3 4
1
1 i i i
n
i
i
k K
x W
F F F F + + + S
= e
e
(6)
wherein:
=S - + 2
1 1 2 (1 ( (1,1) (2,1))) i i i F x DC x DC , (7)
=S + 2
2 3 4 ( (1,2) (2,2)) i i i F x DC x DC (8)
=S + 2
3 3 4 ( (1,1) (2,1)) i i i F x DC x DC (9)
=S - + 2
4 3 4 (1 ( (1,2) (2,2))) i i i F x DC x DC (10)
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[0039] At block 210, the decoupling matrix may be determined by
solving the objective function subject to the satisfaction of one or more
performance constraints 212. The objective function, for example, may be solved
using techniques including a simulated annealing technique, a surrogate-based
optimization technique, an interior point technique, an active set technique, a
sequential programming technique, a linear programming technique, a quadratic
programming technique, a convex programming technique, a nonlinear
programming technique, a robust optimization technique, a stochastic
optimization technique, or the like.
[0040] The performance constraints 212, for example, may include
overshoot time, rise time, decay ratio, settling time, undershoot time, and the like.
The performance constraints comprise the decoupling values and the control gain
parameters as decision variables. The performance constraints 212 may be
generated by a user based upon configuration of the engine system 100 and
efficiency required from the engine system 100. In the presently contemplated
configuration, for the engine 101, the performance constraints 204 may include
settling time of the recirculated exhaust gas 121 (see Fig. 1), settling time of the
boost pressure, overshoot time of the recirculated exhaust gas 121, overshoot
percentage of the recirculated exhaust gas 121, overshoot time of the boost
pressure, undershoot time of the recirculated exhaust gas 121, overshoot
percentage of the boost pressure, undershoot time of the boost pressure,
undershoot percentage of the boost pressure, integral square error, integral
absolute error, undershoot percentage of the recirculated exhaust gas 121. For
example, a settling time performance constraint may be represented by the
following equations:
max(settling timeof recirculated exahust gas ) < desired time period (11)
max(settling timeboost pressure)< desired time period (12)
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20
[0041] Similarly, an overshoot percentage performance constraint may be
represented by the following equation (13):
max(overshoot percentage of recirculated exhaust gas)< desired overshootpercentage
(13)
[0042] At block 212, the first fluid regulation component 120 and the
second fluid regulation component 148 are decoupled based upon the decoupling
matrix and the plurality of control gain parameters. Particularly, at block 212, a
percentage opening of the first fluid regulation component 120 and a percentage
opening of the second fluid regulation component 148 are determined such that
the first fluid regulation component 120 and the second fluid regulation
component 148 are decoupled. For example, at block 212, the percentage
opening of the first fluid regulation component 120 and the percentage opening
of the second fluid regulation component 148 may be determined using the
following equations:
% ( ') ( ') 12 2 11 1 FFRC= W *V + W *V (14)
% ( ') ( ') 21 1 22 2 SFRC= W *V + W *V (15)
' ( , )
1 V = f control gain parameters Exahust gas recirculated error (16)
' ( , )
2 V = f control gain parameters Boost pressure error (17)
Exahust gas recirculated error =DEGR - CEGR (18)
Boost pressure error =DBP - CBP (19)
wherein V1’ is a first intermediate value, V2’ is a second intermediate value,
DEGR is desired amount of recirculated exhaust gas 121 in the intake manifold
106 (see Fig. 1), CEGR is current amount of recirculated exhaust gas in the
intake manifold 106, DBP is desired boost pressure, and CBP is current boost
270399-1
21
pressure. As shown in the equations (16) and (17) the first intermediate value V1’
and the second intermediate value V2’ are determined based upon the control gain
parameters and an error in one or more desired outputs. The equations (16) and
(17), take exhaust gas recirculated error and boost pressure error into account
since the equations (14) – (19), are represented for the desired outputs including
the recirculated exhaust gas in the intake manifold 106 and the current amount of
recirculated exhaust gas in the intake manifold 106. It is noted that while the
equations (14) – (19), are represented for the desired outputs including the
recirculated exhaust gas 121 in the intake manifold 106 and the current amount of
recirculated exhaust gas in the intake manifold 106, the concept of the equations
(14) – (19) may be used for other desired outputs, such as fresh air flow rate into
the intake manifold 106, oxygen fraction in the intake manifold 106, or the like.
[0043] The decoupling of the first fluid regulation component 120 and the
second fluid regulation component 148 results in determination of a percentage
opening of the first fluid regulation component 120 and a percentage opening of
the second fluid regulation component 148. The determination of the percentage
opening of the first fluid regulation component 120 results in directing a desired
amount of the recirculated exhaust gas 121 into the intake manifold 106. In other
words, the determination of the percentage opening of the first fluid regulation
component 120 results in directing a desired amount of the first fraction 121 of
the recirculation exhaust gas 110 into the intake manifold 106. Similarly, the
percentage opening of the second fluid regulation component 148 results in
achieving a desired boost pressure in the intake manifold 106 by distributing the
emission exhaust gas between the high pressure turbine 126 and the low pressure
turbine 130.
[0044] It is noted that the present system and techniques simultaneously
determine one set of decoupling values and one set of control gain parameters
that may used to decouple fluid regulation components across all operating
conditions and all operating frequencies of an engine containing the fluid
regulation components. The decoupling values and the control gain parameters
270399-1
22
may be used to decouple the fluid regulation components to achieve the desired
outputs from the engine. For example, the decoupling values and the control
gains may be used to achieve desired boost pressure, desired oxygen fraction,
desired amount of recirculated exhaust gas, desired air flow rate, or the like.
[0045] While only certain features of the invention have been illustrated
and described herein, many modifications and changes will occur to those skilled
in the art. It is, therefore, to be understood that the appended claims are intended
to cover all such modifications and changes as fall within the true spirit of the
invention.