CN110716431A - Observer-based anti-interference fault-tolerant control method for gas circuit of supercharged diesel engine - Google Patents

Observer-based anti-interference fault-tolerant control method for gas circuit of supercharged diesel engine Download PDF

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CN110716431A
CN110716431A CN201910938505.5A CN201910938505A CN110716431A CN 110716431 A CN110716431 A CN 110716431A CN 201910938505 A CN201910938505 A CN 201910938505A CN 110716431 A CN110716431 A CN 110716431A
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diesel engine
interference
fault
supercharged diesel
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CN110716431B (en
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张健
谢文博
刘龙
赵豪
熊仟
刘岱
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Harbin Engineering University
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Abstract

The invention aims to provide an observer-based anti-interference fault-tolerant control method for a gas circuit of a supercharged diesel engine, which comprises the following steps of: (1) considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the faults of an EGR valve and a VGT guide blade, and establishing a supercharged diesel engine air passage system dynamic model; (2) designing an interference observer according to the supercharged diesel engine gas path system dynamic model in the step (1) for estimating interference introduced by temperature change of an intake manifold and an exhaust manifold; (3) and (3) designing a gas path fault-tolerant controller of the supercharged diesel engine by adopting a self-adaptive technology and an integral sliding mode method, and compensating system disturbance by using the interference estimation value obtained by the observer in the step (2) to realize the anti-interference and fault-tolerant capability of the system. The invention has good fault tolerance for partial failure faults and constant deviation faults of an EGR valve and a VGT guide vane in a gas path of a supercharged diesel engine due to long-term use, and can compensate system interference caused by temperature change of an intake manifold and an exhaust manifold.

Description

Observer-based anti-interference fault-tolerant control method for gas circuit of supercharged diesel engine
Technical Field
The invention relates to a diesel engine gas circuit control system, in particular to a diesel engine gas circuit control system with Exhaust Gas Recirculation (EGR) and variable geometric section turbocharging (VGT).
Background
The main emissions of diesel engines are nitrogen oxides (NOx) and Particulate Matters (PM), and the assembly of EGR and VGT in the gas path can improve the in-cylinder combustion condition, and thus, it is also one of the key technologies to reduce the NOx and PM emissions of diesel engines. The change of the opening degree of the EGR valve and the position of the guide vane of the VGT ensures that the system parameters such as the air inlet and exhaust pressure of the diesel engine and the like change, and because of the stronger coupling effect between the EGR and the VGT, the design coordination controller can more accurately and rapidly complete the air path control, and simultaneously realize the purposes of reducing the emission and improving the fuel economy dynamic property. Traditional EGR and VGT control mainly relies on earlier stage calibration and PID controller, and not only work load is big, and the transient response of system is not timely moreover, and steady state effect is also not ideal enough.
In recent years, researchers at home and abroad try to coordinate control of EGR and VGT by using methods such as variable structure control, T-S fuzzy control, active disturbance rejection control and the like based on a supercharged diesel engine gas path system model. Through retrieval, Chinese patent CN201410364561 adopts an active disturbance rejection control theory to design a feedback compensation control law for a diesel engine EGT-VGT system, so that the external environment disturbance and the dynamic characteristic change of an engine generated along with the working condition are processed, and the rapid tracking of the supercharging pressure and the air inflow is realized by combining a feedforward controller. Chinese patent CN201710721919 proposes a robust nonlinear control method aiming at an engine provided with an EGR, a variable geometry section turbocharger and a throttle valve, and considering system external interference, so that the flow of a compressor and the pressure of an exhaust manifold are close to set reference values. In the study of diesel engine gas circuit control based on model reference sliding mode control in the thesis of lie top root and spring (see Wuhan theory and engineering university school headings 2015, volume 37, phase 10, pages 90-97), a supercharged diesel engine gas circuit sliding mode controller is designed, and the simulation verifies that the proposed control algorithm has better performance than a PI controller.
However, in order to simplify the research, the above methods ignore the internal interference of the system caused by the temperature change of the intake and exhaust manifolds of the diesel engine, and do not consider the influence of the fault conditions of the EGR valve and the VGT guide vane of the gas path actuator on the system due to long-term use, so the prior art still fails to solve the problems of the internal interference and the fault of the system in the actual operation of the diesel engine.
Disclosure of Invention
The invention aims to provide an observer-based anti-interference fault-tolerant control method for a gas path of a supercharged diesel engine, which can inhibit the interference effect caused by the temperature change of the gas path inlet and outlet manifolds of the supercharged diesel engine and still ensure the tracking control of the pressure reference value of the gas path inlet and outlet manifolds under the condition of partial failure and constant deviation fault of an EGR valve and VGT guide vanes.
The purpose of the invention is realized as follows:
the invention discloses an observer-based anti-interference fault-tolerant control method for a gas circuit of a supercharged diesel engine, which is characterized by comprising the following steps of:
(1) considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the faults of an EGR valve and a VGT guide blade, and establishing a supercharged diesel engine air passage system dynamic model;
(2) designing an interference observer according to the supercharged diesel engine gas path system dynamic model in the step (1) for estimating interference introduced by temperature change of an intake manifold and an exhaust manifold;
(3) and (3) designing a gas path fault-tolerant controller of the supercharged diesel engine by adopting a self-adaptive technology and an integral sliding mode method, and compensating system disturbance by using the interference estimation value obtained by the observer in the step (2) to realize the anti-interference and fault-tolerant capability of the system.
The present invention may further comprise:
1. the method comprises the following steps of (1) considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the faults of an EGR valve and a VGT guide vane, and establishing a supercharged diesel engine air passage system dynamic model, wherein the specific process is as follows:
the average value model of the supercharged diesel engine gas circuit system is as follows:
Figure BDA0002222234270000021
Figure BDA0002222234270000022
Figure BDA0002222234270000023
wherein p is1Representing intake manifold pressure, p2Indicating exhaust manifold pressure, PcIndicating compressor power, T1Is intake manifold temperature, T2Is the exhaust manifold temperature, WegrFor gas flow through EGR valve, WtFor gas flow through a variable-geometry turbine, WfIs the amount of fuel injection, ηmFor turbomachine efficiency, τ is the time constant derived from the identification, k1、k2、keK is a parameter derived from the operating conditions of the diesel engine1＝RaT1/V1、ke＝ηvNVd/RaT1、k2＝RaT2/V2，RaIs a gas constant, VdIs the cylinder volume, V, of a diesel engine1Is the intake manifold volume, V2Is the exhaust manifold volume, ηvThe charging efficiency of the diesel engine is shown, N is the rotating speed of the diesel engine,the flow rate of the air compressor is used,is turbine power, kt＝ηtcpT2，cpIs the isobaric specific heat capacity of the gas,
Figure BDA0002222234270000033
gamma 1.4 is the air specific heat ratio, etacFor compressor isentropic efficiency, ηtIsentropic efficiency for turbines;
the working point W is referred to according to the relationship between the flow rate of the compressor and the pressure of the intake manifoldcdIs replaced by
Figure BDA0002222234270000034
And by controlling the pressure p of the intake and exhaust manifolds in the gas circuit1And p2Achieving a control objective;
the supercharged diesel engine takes EGR and VGT as actuators for gas path control, and the input quantity of the gas path control is selected as EGR flow WegrWith turbine flow Wt，
Figure BDA0002222234270000035
Respectively representing the interference amount in the intake and exhaust manifold pressure dynamic model caused by the temperature change of the intake and exhaust manifold;
considering partial failure and constant deviation fault of the EGR valve and the VGT guide vanes, modifying a system dynamic model into the following steps:
Figure BDA0002222234270000036
wherein x is [ p ]1p2Pc]TRepresenting system state variables and control input quantity u1＝Wegr，u2＝Wt；
To describe the actuator failure, note E1(t)、E2(t) is an actuator failure factor and satisfies 0 < Ei(t) is less than or equal to 1, i is 1, and 2 respectively refers to an EGR valve and a VGT guide vane; when the ith actuator is not in failure, Ei(t) ═ 1; when partial failure occurs at the i-th actuator, 0 < Ei(t)＜1；F1(t)、F2(t) represents the unknown bounded constant deviation fault experienced by each actuator, assuming the constant deviation fault norm has an upper bound, i.e.
Figure BDA0002222234270000037
Functions f (x), g1(x)、g2(x) D is defined as follows:
Figure BDA0002222234270000041
Figure BDA0002222234270000042
2. step (2) designing an interference observer according to the supercharged diesel engine gas path system dynamic model in the step (1) for estimating interference introduced by temperature change of an intake manifold and an exhaust manifold, wherein the specific process is as follows:
during the operation of the diesel engine, the expected intake and exhaust manifold pressures are respectively pd1、pd2Indicating, correspondingly, the pressure tracking error s1＝p1-pd1、s2＝p2-pd2S ═ s1s2]T、p＝[p1p2]T、pd＝[p1dp2d]T；
According to the formula
Figure BDA0002222234270000043
Obtaining:
Figure BDA0002222234270000044
wherein u ═ u1u2]TRepresents a control amount, f*(x)、g*(x)、E*(t) and F*(t) are each defined as
Figure BDA0002222234270000045
Figure BDA0002222234270000046
In order to estimate the interference d caused by the temperature change of an intake manifold and an exhaust manifold in a gas path of the supercharged diesel engine, the following interference observer is provided:
Figure BDA0002222234270000047
wherein the content of the first and second substances,
Figure BDA0002222234270000048
represents the observed value of disturbance d, z is an auxiliary variable, k0For adjustable observation gain, κ0Is a positive number.
3. Step (3) adopts a self-adaptive technology and an integral sliding mode method to design a supercharged diesel engine gas path fault-tolerant controller, and utilizes the interference estimation value obtained by the observer in step (2) to compensate system disturbance, thereby realizing the anti-interference and fault-tolerant capability of the system, and the specific process is as follows:
the design of the anti-interference fault-tolerant controller for the gas circuit of the supercharged diesel engine is as follows:
uFTC＝uh+uf
Figure BDA0002222234270000051
uf＝-ζg*(x)-1sgn(σ(t))
wherein u ishAnd ufRespectively representing a nominal control quantity and a fault-tolerant control quantity, and a time-varying control gain zeta is defined as
Figure BDA0002222234270000052
Is calculated on line by the adaptive parameter updating law,
Figure BDA0002222234270000053
ε＞0；
Figure BDA0002222234270000054
represents an estimate of the introduced auxiliary variable phi 1/1-eta in dependence on the failure factor and defines E*||min1/eta, estimating phi on line by an adaptive method, and designing an adaptive parameter updating law as
Figure BDA0002222234270000055
Beta is more than 0 and is an adjustable parameter; fault tolerant control ufIn (d), σ (t) represents an integral sliding mode variable
Figure BDA0002222234270000056
t0Is the system start time.
The invention has the advantages that: the invention has good fault tolerance for partial failure faults and constant deviation faults of an EGR valve and a VGT guide vane in a gas path of a supercharged diesel engine due to long-term use, and can compensate system interference caused by temperature change of an intake manifold and an exhaust manifold. In addition, the controller designed by adopting the integral sliding mode theory has the advantage of insensitivity to working condition change, and can inhibit interference when the controller starts to act, so that the system robustness is improved.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a graph showing a comparison of exhaust manifold pressure tracking results from FTC control versus conventional SMC control;
FIG. 3 is a simulation comparison diagram of the compressor flow tracking effect under the action of an FTC controller and a traditional SMC controller;
Detailed Description
The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:
with reference to fig. 1-3, the invention relates to an observer-based anti-interference fault-tolerant control method for a gas circuit of a supercharged diesel engine, which comprises the following implementation steps:
step one, considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the possible faults of an EGR valve and a VGT guide blade, establishing a supercharged diesel engine air passage system dynamic model:
the average value model of the supercharged diesel engine gas circuit system is as follows:
Figure BDA0002222234270000061
Figure BDA0002222234270000062
wherein p is1Representing intake manifold pressure, p2To representExhaust manifold pressure, PcIndicating compressor power, T1Is intake manifold temperature, T2Is the exhaust manifold temperature, WegrFor gas flow through EGR valve, WtFor gas flow through a variable-geometry turbine, WfIs the amount of fuel injection, ηmFor turbomachine efficiency, τ is the time constant derived from the identification, k1、k2、keK is a parameter derived from the operating conditions of the diesel engine1＝RaT1/V1、ke＝ηvNVd/RaT1、k2＝RaT2/V2，RaIs a gas constant, VdIs the cylinder volume, V, of a diesel engine1Is the intake manifold volume, V2Is the exhaust manifold volume, ηvThe charging efficiency of the diesel engine is shown, N is the rotating speed of the diesel engine,the flow rate of the air compressor is used,
Figure BDA0002222234270000065
is turbine power, kt＝ηtcpT2，cpIs the isobaric specific heat capacity of the gas,
Figure BDA0002222234270000066
gamma 1.4 is the air specific heat ratio, etacFor compressor isentropic efficiency, ηtIs the turbine isentropic efficiency.
For supercharged diesel engines, the compressor flow WcAnd exhaust manifold pressure p2Influencing the air flow into the diesel engine and the EGR rate, W can becAnd p2As system state variables. In practice, however, to avoid calculating WcAnd its reference working point WcdWill refer to the operating point W based on the relationship between compressor flow and intake manifold pressurecdIs replaced by
Figure BDA0002222234270000071
And by controlling the pressure p of the intake and exhaust manifolds in the gas circuit1And p2The control objective is achieved. The supercharged diesel engine takes EGR and VGT as actuators for gas path control, so the input quantity of the gas path control is selected as EGR flow WegrWith turbine flow Wt. In formulae (1) to (3)
Figure BDA0002222234270000072
Respectively, represent the amount of disturbance in the intake and exhaust manifold pressure dynamics model due to intake and exhaust manifold temperature changes.
Considering partial failure and constant deviation fault of EGR and VGT, modifying a system dynamic model into:
wherein x is [ p ]1p2Pc]TRepresenting system state variables and control input quantity u1＝Wegr，u2＝Wt。
To describe the actuator failure, note E1(t)、E2(t) is an actuator failure factor and satisfies 0 < Ei(t) 1, i 1,2 EGR valve and VGT guide vane, respectively. When the ith actuator is not in failure, Ei(t) ═ 1; when partial failure occurs at the i-th actuator, 0 < Ei(t)＜1。F1(t)、F2(t) represents the unknown bounded constant deviation fault experienced by each actuator, assuming the constant deviation fault norm has an upper bound, i.e.
Figure BDA0002222234270000074
In formula (4), the functions f (x), g1(x)、g2(x) D is defined as follows:
Figure BDA0002222234270000075
step two, designing an interference observer according to the supercharged diesel engine gas path dynamic model in the step one, and estimating interference introduced by temperature change of an intake manifold and an exhaust manifold:
during the operation of the diesel engine, the expected intake and exhaust manifold pressures are respectively pd1、pd2Indicating, correspondingly, the pressure tracking error s1＝p1-pd1、s2＝p2-pd2. For the convenience of controller design, remember s ═ s1s2]T、p＝[p1p2]T、pd＝[p1dp2d]T。
From equation (4), one can obtain:
Figure BDA0002222234270000081
wherein u ═ u1u2]TRepresents a control amount, f*(x)、g*(x)、E*(t) and F*(t) is defined as:
Figure BDA0002222234270000082
Figure BDA0002222234270000083
in order to estimate the interference d caused by the temperature change of an intake manifold and an exhaust manifold in a gas path of the supercharged diesel engine, the following interference observer is provided:
Figure BDA0002222234270000084
wherein the content of the first and second substances,
Figure BDA0002222234270000085
an observed value representing interference d, z being an auxiliary variable, an adjustable observed gain k0、κ0Is a positive number.
According toEquation (6), calculating
Figure BDA0002222234270000086
Second derivative with respect to time:
Figure BDA0002222234270000087
laplace transformation is performed on the formula (7), and the following results are obtained:
Figure BDA0002222234270000088
therefore, it can be inferred that when κ0When the value is large enough, the observer outputs
Figure BDA0002222234270000089
The observer, which will converge to the true value of d, equation (6), is able to accurately estimate the disturbance caused by intake and exhaust manifold temperature changes.
Thirdly, designing a supercharged diesel engine gas path fault-tolerant controller by adopting a self-adaptive technology and an integral sliding mode method, and compensating system disturbance by using the interference estimation value obtained by the observer in the second step to realize the anti-interference and fault-tolerant capability of the system:
first, consider a boosted diesel engine gas path nominal system that does not contain actuator failures, i.e., systems (1) - (3). The following nominal controller was designed:
Figure BDA0002222234270000091
constructing a Lyapunov function
Figure BDA0002222234270000092
And deriving it yields:
Figure BDA0002222234270000093
it is clear that,
Figure BDA0002222234270000094
the variable s thus converges asymptotically to zero, i.e., p1、p2Respectively converge on p asymptotically1d、p2d。
However, the nominal controller (9) can only inhibit the interference of temperature variation inside the system, and in order to further overcome the failures and constant deviation faults of EGR and VGT parts in the gas path of the supercharged diesel engine, a fault-tolerant control algorithm needs to be designed.
Taking the following integral sliding mode variables:
Figure BDA0002222234270000095
wherein, t0Represents the system start time, and σ (t) is hereinafter referred to as σ.
By deriving σ according to equation (11), we can obtain:
Figure BDA0002222234270000096
the method is characterized in that an anti-interference fault-tolerant controller of a supercharged diesel engine gas circuit is designed by combining an adaptive parameter identification technology as follows:
uFTC＝uh+uf(13)
Figure BDA0002222234270000097
uf＝-γg*(x)-1sgn(σ) (15)
wherein u ishAnd ufRespectively representing a nominal control quantity and a fault-tolerant control quantity.
Figure BDA0002222234270000101
ε is greater than 0. Defining an auxiliary variable phi related to the failure factor, and phi is 1/1-eta, | | E*||min1/η. Estimating phi on line by a self-adaptive method, and designing a self-adaptive parameter updating law as follows:
Figure BDA0002222234270000102
wherein beta is more than 0 and is an adjustable parameter. Noting the parameter estimation error as
Figure BDA0002222234270000103
Taking the following Lyapunov function, analyzing the stability of the closed-loop system:
Figure BDA0002222234270000104
the derivative of V is obtained according to equations (12) and (16):
Figure BDA0002222234270000105
substituting the controllers (13) - (15) into equation (18) then there are:
considering the failure factor definition, it can be known that E*∈[0,1]I.e. | | Δ E*I < 1, so:
Figure BDA0002222234270000107
it is clear that,
Figure BDA0002222234270000111
according to V2The definition of (1) is that | | | σ | | | is equal to L∞、
Figure BDA0002222234270000112
By integrating the two ends of the above formula, it can be known that | | | σ | | | belongs to L2∩L∞. At the same time, it is easy to prove
Figure BDA0002222234270000113
Then there are
Figure BDA0002222234270000114
When σ is 0, it can be seen from equation (12),
Figure BDA0002222234270000115
i.e. the amount of control caused by actuator failureCan be represented by-g*(x)ΔE*uhAnd (4) counteracting. Therefore, according to equation (5), there is this time
Figure BDA0002222234270000116
Equivalent to the nominal system case, and the controller (13) is simplified to
Figure BDA0002222234270000117
According to pairs
Figure BDA0002222234270000118
And analysis of its derivative, the intake manifold pressure p is known1Exhaust manifold pressure p2Can converge to respective desired values p asymptotically1d、p2d。
Example (c):
step one, considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the possible faults of an EGR valve and a VGT guide blade, establishing a supercharged diesel engine air passage system dynamic model:
the average value model of the supercharged diesel engine gas circuit system is as follows:
Figure BDA0002222234270000119
Figure BDA00022222342700001110
wherein p is1Representing intake manifold pressure, p2Indicating exhaust manifold pressure, PcIndicating compressor power, T1Is intake manifold temperature, T2Is the exhaust manifold temperature, WegrFor gas flow through EGR valve, WtFor gas flow through a variable-geometry turbine, WfIs the amount of fuel injection, ηmFor turbomachine efficiency, τ is the time constant derived from the identification, k1、k2、keK is a parameter derived from the operating conditions of the diesel engine1＝RaT1/V1、ke＝ηvNVd/RaT1、k2＝RaT2/V2，RaIs a gas constant, VdIs the cylinder volume, V, of a diesel engine1Is the intake manifold volume, V2Is the exhaust manifold volume, ηvThe charging efficiency of the diesel engine is shown, N is the rotating speed of the diesel engine,
Figure BDA0002222234270000121
the flow rate of the air compressor is used,
Figure BDA0002222234270000122
Wtis turbine power, kt＝ηtcpT2，cpIs the isobaric specific heat capacity of the gas,
Figure BDA0002222234270000123
gamma 1.4 is the air specific heat ratio, etacFor compressor isentropic efficiency, ηtIs the turbine isentropic efficiency.
For supercharged diesel engines, the compressor flow WcAnd exhaust manifold pressure p2Influencing the air flow into the diesel engine and the EGR rate, W can becAnd p2As system state variables. In practice, however, to avoid calculating WcAnd its reference working point WcdWill refer to the operating point W based on the relationship between compressor flow and intake manifold pressurecdIs replaced by
Figure BDA0002222234270000124
And by controlling the pressure p of the intake and exhaust manifolds in the gas circuit1And p2The control objective is achieved. The supercharged diesel engine takes EGR and VGT as actuators for gas path control, so the input quantity of the gas path control is selected as EGR flow WegrWith turbine flow Wt. In formulae (1) to (3)Respectively, represent the amount of disturbance in the intake and exhaust manifold pressure dynamics model due to intake and exhaust manifold temperature changes.
Considering partial failure and constant deviation fault of EGR and VGT, modifying a system dynamic model into:
Figure BDA0002222234270000126
wherein x is [ p ]1p2Pc]TRepresenting system state variables and control input quantity u1＝Wegr，u2＝Wt。
To describe the actuator failure, note E1(t)、E2(t) is an actuator failure factor and satisfies 0 < Ei(t) 1, i 1,2 EGR valve and VGT guide vane, respectively. When the ith actuator is not in failure, Ei(t) ═ 1; when partial failure occurs at the i-th actuator, 0 < Ei(t)＜1。F1(t)、F2(t) represents the unknown bounded constant deviation fault experienced by each actuator, assuming the constant deviation fault norm has an upper bound, i.e.
Figure BDA0002222234270000127
In formula (4), the functions f (x), g1(x)、g2(x) D is defined as follows:
Figure BDA0002222234270000131
Figure BDA0002222234270000132
in this example, according to the modeling requirement of supercharged diesel engine gas circuit dynamics model, carry out parameter measurement and parameter processing to relevant quantity in the gas circuit:
V1is the intake manifold volume, V1＝0.22m3；
V2Is the exhaust manifold volume, V2＝0.2m3；
VdIs the cylinder volume, V, of a diesel engined＝0.127m3；
N is the rotation speed of the diesel engine, and N is 1500 rpm;
Tais the outside air temperature, Ta＝300K；
RaIs a gas constant, Ra＝0.287kJ/kg/K；
T1Is intake manifold temperature, T1＝300K；
T2Is the exhaust manifold temperature, T2＝693K；
ηvEfficiency of charging of diesel engines, ηv＝0.87；
ηtFor turbine isentropic efficiency, ηt＝0.76；
ηcFor compressor isentropic efficiency, ηc＝0.61；
ηmFor turbo-mechanical efficiency, ηm＝0.95；
cpIs the isobaric specific heat capacity of the gas, cp＝1.117kJ/kg/K；
Wherein, gamma is 1.4, the air specific heat ratio;
τ is a time constant τ of 0.15 obtained by the recognition.
In summary, the value of each parameter in the supercharged diesel engine gas path dynamic model is k1＝391.36、k2＝994.46、kt＝588.3、ke＝0.018、kc＝0.0018、ηm＝0.95、μ＝0.285、τ＝0.15。
Step two, designing an interference observer according to the supercharged diesel engine gas path dynamic model in the step one, and estimating interference introduced by temperature change of an intake manifold and an exhaust manifold:
during the operation of the diesel engine, the expected intake and exhaust manifold pressures are respectively pd1、pd2Indicating, correspondingly, the pressure tracking error s1＝p1-pd1、s2＝p2-pd2. For the convenience of controller design, remember s ═ s1s2]T、p＝[p1p2]T、pd＝[p1dp2d]T。
Estimating the interference d caused by the temperature change of an intake manifold and an exhaust manifold in the air path of the supercharged diesel engine by adopting the interference observer of the formula (4):
Figure BDA0002222234270000141
wherein the parameter κ is adjustable0、κ1Respectively is k0＝20、κ1＝1。
Interference observed value output by formula (5)
Figure BDA0002222234270000142
Can converge to the true value of d, can be adopted in the controllerThe disturbances caused by the intake and exhaust manifold temperature changes are compensated for.
Thirdly, designing a supercharged diesel engine gas path fault-tolerant controller by adopting a self-adaptive technology and an integral sliding mode method, and compensating system disturbance by using the interference estimation value obtained by the observer in the second step to realize the anti-interference and fault-tolerant capability of the system:
the anti-interference fault-tolerant controller of supercharged diesel engine gas circuit is:
uFTC＝uh+uf(6)
uf＝-ζg*(x)-1sgn(σ(t)) (8)
wherein u ishAnd ufRespectively representing a nominal control quantity and a fault-tolerant control quantity. The time-varying control gain ζ is defined as
Figure BDA0002222234270000145
Is calculated on line by the adaptive parameter updating law,
Figure BDA0002222234270000146
ε＞0。
Figure BDA0002222234270000151
represents an estimate of the introduced auxiliary variable phi 1/1-eta in dependence on the failure factor and defines E*||min1/η. The phi is estimated on line by an adaptive method, and the designed adaptive parameter updating law is
Figure BDA0002222234270000152
Beta is more than 0 and is an adjustable parameter. Fault tolerant control ufIn (d), σ (t) represents an integral sliding mode variable
Figure BDA0002222234270000153
t0Is the system start time.
In simulation, a traditional sliding mode variable structure controller (marked as SMC) is compared with an anti-interference fault-tolerant controller (marked as FTC) provided by the patent. The system initial state is set as: p is a radical of1＝1.32bar，p2＝1.35bar，Pc5.605W. The disturbance caused by the intake and exhaust manifold temperature change is d ═ 0.0002sin (0.05t) 0.0003cos (0.04t)]T. At 25 seconds, a failure factor E is introduced to the EGR valve and VGT vanesiPartial failure fault of (t) ═ 0.8+0.05sin (0.2 π t), constant deviation fault F (t) ═ 0.0003sin (0.05t) 0.0005cos (0.03t)]T。
Based on firewoodObtaining the flow W of the compressor under the actual operation condition of the oil enginecExhaust manifold pressure p2And fuel mass flow WfThe set reference values, as shown in table 1:
TABLE 1 operating state reference values for supercharged diesel engines
Figure BDA0002222234270000154
In the controllers (6) to (8), the parameter values are respectively taken as
Figure BDA0002222234270000155
η＝0.3、β＝1。
The simulation verification result shows that: according to the observer-based supercharged diesel engine gas circuit anti-interference fault-tolerant control method, the observer is used for compensating the interference effect of the temperature change of the gas inlet and outlet manifolds on the system, and the fault-tolerant controller overcomes the possible partial failure fault and constant deviation fault of the EGR valve and the VGT guide vane, so that the stable operation of the system under the fault condition is ensured, and the robustness and the reliability of the supercharged diesel engine gas circuit control are improved.

Claims (4)

1. An observer-based anti-interference fault-tolerant control method for a gas circuit of a supercharged diesel engine is characterized by comprising the following steps of:
(1) considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the faults of an EGR valve and a VGT guide blade, and establishing a supercharged diesel engine air passage system dynamic model;
(2) designing an interference observer according to the supercharged diesel engine gas path system dynamic model in the step (1) for estimating interference introduced by temperature change of an intake manifold and an exhaust manifold;
(3) and (3) designing a gas path fault-tolerant controller of the supercharged diesel engine by adopting a self-adaptive technology and an integral sliding mode method, and compensating system disturbance by using the interference estimation value obtained by the observer in the step (2) to realize the anti-interference and fault-tolerant capability of the system.
2. The observer-based anti-interference fault-tolerant control method for the gas path of the supercharged diesel engine according to claim 1, characterized in that: the method comprises the following steps of (1) considering the interference generated by the temperature change of an air inlet manifold and an air outlet manifold of a supercharged diesel engine air passage and the faults of an EGR valve and a VGT guide vane, and establishing a supercharged diesel engine air passage system dynamic model, wherein the specific process is as follows:
the average value model of the supercharged diesel engine gas circuit system is as follows:
Figure FDA0002222234260000011
Figure FDA0002222234260000012
Figure FDA0002222234260000013
wherein p is1Representing intake manifold pressure, p2Indicating exhaust manifold pressure, PcIndicating compressor power, T1Is intake manifold temperature, T2Is the exhaust manifold temperature, WegrFor gas flow through EGR valve, WtFor gas flow through a variable-geometry turbine, WfIs the amount of fuel injection, ηmFor turbomachine efficiency, τ is the time constant derived from the identification, k1、k2、keK is a parameter derived from the operating conditions of the diesel engine1＝RaT1/V1、ke＝ηvNVd/RaT1、k2＝RaT2/V2，RaIs a gas constant, VdIs the cylinder volume, V, of a diesel engine1Is the intake manifold volume, V2Is the exhaust manifold volume, ηvThe charging efficiency of the diesel engine is shown, N is the rotating speed of the diesel engine,
Figure FDA0002222234260000021
the flow rate of the air compressor is used,
Figure FDA0002222234260000022
is turbine power, kt＝ηtcpT2，cpIs the isobaric specific heat capacity of the gas,
Figure FDA0002222234260000023
gamma 1.4 is the air specific heat ratio, etacFor compressor isentropic efficiency, ηtIsentropic efficiency for turbines;
the working point W is referred to according to the relationship between the flow rate of the compressor and the pressure of the intake manifoldcdIs replaced byAnd by controlling the pressure p of the intake and exhaust manifolds in the gas circuit1And p2Achieving a control objective;
the supercharged diesel engine takes EGR and VGT as actuators for gas path control, and the input quantity of the gas path control is selected as EGR flow WegrWith turbine flow Wt，
Figure FDA0002222234260000025
Respectively representing the interference amount in the intake and exhaust manifold pressure dynamic model caused by the temperature change of the intake and exhaust manifold;
considering partial failure and constant deviation fault of the EGR valve and the VGT guide vanes, modifying a system dynamic model into the following steps:
Figure FDA0002222234260000026
wherein x is [ p ]1p2Pc]TRepresenting system state variables and control input quantity u1＝Wegr，u2＝Wt；
To describe the actuator failure, note E1(t)、E2(t) is an actuator failure factor and satisfies 0 < Ei(t) is less than or equal to 1, i is 1, and 2 respectively refers to an EGR valve and a VGT guide vane; when the ith actuator is not in failure, Ei(t) ═ 1; when partial failure occurs at the i-th actuator, 0 < Ei(t)＜1；F1(t)、F2(t) represents the unknown bounded constant deviation fault experienced by each actuator, assuming the constant deviation fault norm has an upper bound, i.e.
Functions f (x), g1(x)、g2(x) D is defined as follows:
Figure FDA0002222234260000028
Figure FDA0002222234260000031
3. the observer-based anti-interference fault-tolerant control method for the gas path of the supercharged diesel engine according to claim 1, characterized in that: step (2) designing an interference observer according to the supercharged diesel engine gas path system dynamic model in the step (1) for estimating interference introduced by temperature change of an intake manifold and an exhaust manifold, wherein the specific process is as follows:
during the operation of the diesel engine, the expected intake and exhaust manifold pressures are respectively pd1、pd2Indicating, correspondingly, the pressure tracking error s1＝p1-pd1、s2＝p2-pd2S ═ s1s2]T、p＝[p1p2]T、pd＝[p1dp2d]T；
According to the formula
Figure FDA0002222234260000032
Obtaining:
Figure FDA0002222234260000033
wherein u ═ u1u2]TRepresents a control amount, f*(x)、g*(x)、E*(t) and F*(t) are each defined as
Figure FDA0002222234260000035
In order to estimate the interference d caused by the temperature change of an intake manifold and an exhaust manifold in a gas path of the supercharged diesel engine, the following interference observer is provided:
Figure FDA0002222234260000036
wherein the content of the first and second substances,
Figure FDA0002222234260000037
represents the observed value of disturbance d, z is an auxiliary variable, k0For adjustable observation gain, κ0Is a positive number.
4. The observer-based anti-interference fault-tolerant control method for the gas path of the supercharged diesel engine according to claim 1, characterized in that: step (3) adopts a self-adaptive technology and an integral sliding mode method to design a supercharged diesel engine gas path fault-tolerant controller, and utilizes the interference estimation value obtained by the observer in step (2) to compensate system disturbance, thereby realizing the anti-interference and fault-tolerant capability of the system, and the specific process is as follows:
the design of the anti-interference fault-tolerant controller for the gas circuit of the supercharged diesel engine is as follows:
uFTC＝uh+uf
Figure FDA0002222234260000041
uf＝-ζg*(x)-1sgn(σ(t))
wherein u ishAnd ufRespectively representing a nominal control quantity and a fault-tolerant control quantity, and a time-varying control gain zeta is defined as
Figure FDA0002222234260000042
Is calculated on line by the adaptive parameter updating law,ε＞0；
Figure FDA0002222234260000045
represents an estimate of the introduced auxiliary variable phi 1/1-eta in dependence on the failure factor and defines E*||min1/eta, estimating phi on line by an adaptive method, and designing an adaptive parameter updating law as
Figure FDA0002222234260000046
Beta is more than 0 and is an adjustable parameter; fault tolerant control ufIn (d), σ (t) represents an integral sliding mode variable
Figure FDA0002222234260000047
t0Is the system start time.
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