Fuel cell air inlet system control method based on high-order all-drive

Abstract

The invention provides a fuel cell air inlet system control method based on high-order all-drive, and relates to the technical field of fuel cells, and the method comprises the following steps: constructing a kinetic model of a fuel cell air inlet system, and obtaining a state space model of the kinetic model; constructing an initial high-order all-drive model based on the state space model; adding unknown disturbance into the initial high-order all-drive model to obtain a high-order all-drive optimal control model; and constructing a control law based on the high-order all-drive optimal control model, and controlling the fuel cell air inlet system based on the control law. According to the method, a control law is designed by adopting an all-drive optimal control framework, nonlinear terms of the system are counteracted, a linear steady closed-loop system is obtained, and decoupling control over key variables of the air inlet system is achieved.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to a fuel cell intake system control method based on high-order all-wheel drive. Background Art

[0002] Proton Exchange Membrane Fuel Cell (PEM FC) is a key device for efficient application of hydrogen energy. It is generally regarded as the ultimate goal of the development of new energy vehicles because of its advantages such as cleanliness, high efficiency, long life and low noise. For high-power PEMFC used in automobiles, the control effect of the intake system plays a vital role in the output power of PEMFC and extending its life. The dynamic performance of PEMFC is closely related to the cathode gas supply. For example, insufficient gas supply or excessive pressure difference between the cathode and the anode will damage the proton exchange membrane and reduce its service life. At the same time, the intake system of the proton exchange membrane fuel cell is a complex dynamic system with multiple inputs and multiple outputs, strong nonlinearity and strong coupling, unmodeled dynamics in the system, and interference from unknown variables outside the system. Therefore, it is necessary to accurately decouple the cathode gas flow and cathode pressure to avoid affecting the efficient and stable operation of the fuel cell. Most of the mature control methods currently available are based on first-order state space equations, but they have certain limitations for highly nonlinear systems. Summary of the invention

[0003] The purpose of the present invention is to provide a fuel cell intake system control method based on high-order all-wheel drive, adopt an all-wheel drive optimal control framework to design a control law, offset the nonlinear terms of the system, obtain a linear steady-state closed-loop system, and realize decoupling control of key variables of the intake system.

[0004] A fuel cell intake system control method based on high-order all-wheel drive, comprising:

[0005] A dynamic model of the fuel cell intake system is constructed, and a state space model of the dynamic model is obtained; the expression is:

[0006]

[0007] Where: x1 = ω cp , is the motor angular velocity of the air compressor in the fuel cell intake system, x2=P sm , is the air pressure of the cathode intake manifold in the fuel cell intake system, x3=P ca , is the cathode pressure of the fuel cell stack in the fuel cell intake system, x4=θ, is the throttle opening in the fuel cell intake system, ξ is the known current disturbance, h(x1,x2)=W cp , is the mass flow rate of air at the outlet of the air compressor, u1 is the air compressor voltage, u2=θ *, is the throttle opening instruction, · is the derivative, b1 is the first state parameter, b2 is the second state parameter, b3 is the third state parameter, b4 is the fourth state parameter, b5 is the fifth state parameter, b6 is the sixth state parameter, b7 is the seventh state parameter, b8 is the eighth state parameter, b9 is the ninth state parameter, b 10 is the tenth state parameter, b 11 is the eleventh state parameter, b 12 is the twelfth state parameter;

[0008] An initial high-order all-wheel drive model is constructed based on the state space model; the expression is:

[0009]

[0010] Where: T is the transpose, x is the state vector, x = [x1, x2, x3, x4], L 12 =0,L 21 =0,

[0011] Adding unknown disturbances to the initial high-order all-wheel drive model, a high-order all-wheel drive optimal control model is obtained; the expression is:

[0012]

[0013] Where: is the first unknown disturbance, is the second unknown disturbance, 0~1 represents the 0th and 1st derivatives;

[0014] A control law is constructed based on the high-order all-wheel drive optimal control model, and a fuel cell intake system is controlled based on the control law.

[0015] Optionally, the expression of the kinetic model is:

[0016]

[0017] Where: J cp is the motor moment of inertia, t is time, τ cm is the motor driving torque, τ cp is the load torque of the air compressor, R is the gas constant of air, T cp is the gas temperature inside the pipe, V sm is the volume of the gas supply pipeline, M a is the molar mass of the gas, W sm is the mass flow rate of the gas supply pipeline, T fc is the stack temperature, V ca is the volume of the stack cathode, Wca,out is the cathode outlet flow rate, is the molar mass of oxygen, is the oxygen flow rate participating in the reaction, T tr is the response time constant of the valve.

[0018] Optionally, b 12 =T tr , η cm , k t , k v and R cm is the motor constant, C p is the specific heat capacity of gas, T atm is the atmospheric temperature, η cp is the maximum efficiency of the air compressor, γ is the air ratio, R a is the air gas constant, k sm is the outlet flow coefficient of the construction period pipeline, T st is the stack temperature, n cell is the number of batteries connected in series, F is the Faraday constant, C D,tr is the throttle valve discharge coefficient, A T,tr is the maximum throttling area.

[0019] Optionally, an unknown disturbance is added to the initial high-order all-wheel drive model to obtain a high-order all-wheel drive optimal control model, specifically:

[0020] Construct an extended state observer; the expression is:

[0021]

[0022] Where: Φ 1,j is the first expansion state parameter, Φ 2,j is the second expansion state parameter, Φ 3,j is the third expansion state parameter, j = [1,2]; Φ 1,j The observed value of Φ 2,j The observed value of Φ 3,j The observed value of β 1,j is the first observer gain vector, β 2,j is the second observer gain vector, β 3,j is the third observer gain vector;

[0023] Input y1=x2 into the extended state observer and we get Input y2=x3 into the extended state observer, and we get

[0024] Add to the initial high-order all-wheel drive model and The high-order all-wheel drive optimal control model is obtained.

[0025] Optionally, constructing a control law based on the high-order all-wheel drive optimal control model, and controlling the fuel cell intake system based on the control law includes:

[0026] make i∈{2,3}; is the ideal state variable;

[0027] The high-order all-wheel drive optimal control model is converted into a linear state to obtain a linear model; the expression is:

[0028]

[0029] Where: A E is the first parameter matrix, B E is the second parameter matrix;

[0030] make

[0031]

[0032] Construct the objective function; the expression is:

[0033]

[0034] Where: J is the objective function, is a positive semidefinite matrix, is a positive definite matrix, and the objective function J aims to minimize the rate of change of the state variables;

[0035] Based on the objective function, the Riccati algebraic equation is obtained to obtain a unique positive solution;

[0036] A control law is constructed based on the unique positive solution, and a fuel cell intake system is controlled based on the control law.

[0037] Optionally, the control law expression is:

[0038]

[0039] Where: u is the controller output, P is the only positive solution, t is the time, f(x (0～1) )=f(z (0～1) ,t), is the lumped disturbance, representing and

[0040] Optionally,

[0041] The effects of the present invention are as follows:

[0042] The present invention is based on a fuel cell intake system control method of a high-order all-wheel drive. For the decoupling control problem of the fuel cell intake system, an optimal controller based on a high-order all-wheel drive system method combined with an extended state observer is designed. The method process is simple, easy to understand, and has strong robustness. The extended state observer is used to observe the parameter uncertainty of the system and the lumped disturbance formed by external interference. No prior information of external interference is required, and it can effectively overcome the unmodeled dynamics between the control model and the topological model; the high-order all-wheel drive method is used. Compared with the traditional control method, it is no longer based on the state space model for analysis and design, and the model processing process is simple; the structural design of the controller is simple and effective, combined with the optimal control parameterization design method, the parameter solution process is simple and clear and has good numerical stability, and can provide sufficient design freedom to obtain controller parameters that meet the expected performance indicators of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of a fuel cell intake system control method based on high-order all-wheel drive of the present invention;

[0044] Figure 2 It is a schematic diagram of a load condition in which the present invention is applied to tracking a given expected signal;

[0045] Figure 3 It is a schematic diagram of throttle opening comparison applied to tracking a given desired signal;

[0046] Figure 4 It is a schematic diagram of the air compressor voltage comparison applied to track a given desired signal;

[0047] Figure 5 is a schematic diagram of cathode pressure comparison applied to track a given desired signal;

[0048] Figure 6 It is a schematic diagram of air flow comparison applied to track a given desired signal. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0050] Figure 1 This is a flow chart of the fuel cell intake system control method based on high-level all-wheel drive of the present invention. Figure 1 As shown, the present invention provides a fuel cell intake system control method based on high-order all-wheel drive, which includes:

[0051] S1, constructing a dynamic model of a fuel cell intake system and obtaining a state space model of the dynamic model.

[0052] Preferably, the kinetic model expression is:

[0053]

[0054] Where: J cp is the motor moment of inertia, t is time, τ cm is the motor driving torque, τ cp is the load torque of the air compressor, R is the gas constant of air, T cp is the gas temperature inside the pipe, V sm is the volume of the gas supply pipeline, M a is the molar mass of the gas, W sm is the mass flow rate of the gas supply pipeline, T fc is the stack temperature, V ca is the volume of the cathode of the battery stack, W ca,out is the cathode outlet flow rate, is the molar mass of oxygen, is the oxygen flow rate participating in the reaction, T tr is the valve response time constant.

[0055] The state space model expression is:

[0056]

[0057] Where: x1 = ω cp , is the motor angular velocity of the air compressor in the fuel cell intake system, x2=P sm , is the air pressure of the cathode intake manifold in the fuel cell intake system, x3=P ca , is the cathode pressure of the fuel cell stack in the fuel cell intake system, x4=θ, is the throttle opening in the fuel cell intake system, ξ is the known current disturbance, h(x1,x2)=W cp , is the mass flow rate of air at the outlet of the air compressor, u1 is the air compressor voltage, u2=θ * , is the throttle opening instruction, · is the derivative, b1 is the first state parameter, b2 is the second state parameter, b3 is the third state parameter, b4 is the fourth state parameter, b5 is the fifth state parameter, b6 is the sixth state parameter, b7 is the seventh state parameter, b8 is the eighth state parameter, b9 is the ninth state parameter, b 10 is the tenth state parameter, b 11 is the eleventh state parameter, b 12 is the twelfth state parameter, b 12=T tr , η cm , k t , k v and R cm is the motor constant, C p is the specific heat capacity of gas, T atm is the atmospheric temperature, η cp is the maximum efficiency of the air compressor, γ is the air ratio, R a is the air gas constant, k sm is the outlet flow coefficient of the construction period pipeline, T st is the stack temperature, n cell is the number of batteries connected in series, F is the Faraday constant, C D,tr is the throttle valve discharge coefficient, A T,tr is the maximum throttling area.

[0059] S2, builds the initial high-order all-wheel drive model based on the state space model. The expression is:

[0060]

[0061] Where: T is the transpose, x is the state vector, x = [x1, x2, x3, x4], L 12 =0,L 21 =0,

[0063] Specifically, the state space model is simplified to obtain:

[0064]

[0065] Respectively and Derivation, get

[0066]

[0067] Will Substituting into the above formula, we can obtain the initial high-order all-wheel drive model.

[0068] S3, adding unknown disturbances to the initial high-order all-wheel drive model to obtain the high-order all-wheel drive optimal control model. The expression is:

[0069]

[0070] Where: is the first unknown disturbance, is the second unknown disturbance, 0~1 represents the 0th order derivative and the 1st order derivative.

[0071] Specifically, S3 includes:

[0072] Construct an extended state observer; the expression is:

[0073]

[0075] Where: Φ 1,j is the first expansion state parameter, Φ 2,j is the second expansion state parameter, Φ 3,j is the third expansion state parameter, j = [1, 2]; Φ 1,j The observed value of Φ 2,j The observed value of Φ 3,j The observed value of β 1,j is the first observer gain vector, β 2,j is the second observer gain vector, β 3,j is the third observer gain vector.

[0076] Input y1=x2 into the extended state observer and we get Input y2=x3 into the extended state observer and we get

[0077] Added to the initial high-level all-wheel drive model and The high-order all-wheel drive optimal control model is obtained.

[0078] exist and Under the boundedness assumption, the estimation error of the observer is bounded and can be adjusted by adjusting the observer bandwidth ω 0,i To adjust the observation tracking error, generally the larger the bandwidth, the more accurate the estimation; however, a larger bandwidth will increase noise sensitivity, so the appropriate bandwidth should be selected between tracking performance and noise tolerance.

[0079] S4, constructs a control law based on a high-order all-wheel drive optimal control model, and controls the fuel cell intake system based on the control law.

[0080] Furthermore, S4 includes:

[0081] S41, order i∈{2,3}; is the ideal state variable.

[0082] S42, converting the high-order all-wheel drive optimal control model into a linear state to obtain a linear model; the expression is:

[0083]

[0084] Where: is the first parameter matrix, is the second parameter matrix.

[0085] S43, order

[0086]

[0087] S44, construct the objective function. The expression is:

[0088]

[0089] Where: J is the objective function, is a positive semidefinite matrix, is a positive definite matrix, and the objective function J aims to minimize the rate of change of the state variables.

[0090] S45, based on the objective function, the Riccati algebraic equation is solved and the unique positive solution is obtained. The expression of the Riccati algebraic equation is:

[0091] A T P+PA-PBR -1 B T P+Q=0;

[0092] Where: P is the only positive solution, is the third parameter matrix.

[0093] The controller gain is

[0094] The corresponding closed-loop system:

[0095]

[0096] Since the matrix A-BR -1 B T P is Hurwitzian, so the system is asymptotically stable.

[0097] S46, constructing a control law based on the unique positive solution, and controlling the fuel cell intake system based on the control law.

[0098] Preferably, S46 is specifically:

[0099] The control law is constructed based on the unique positive solution; the expression is:

[0100]

[0101] Where: u is the controller output, P is the only positive solution, t is the time, is the lumped disturbance, representing and

[0102] Controller gain

[0103] Specifically, taking a fuel cell intake system as an example, it is applied to track the load condition of a given desired signal such as Figure 2 As shown, the method of the present invention is compared with the existing multi-output feedback linearization + ESO and feedback linearization + ESO. The results are as follows Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown in the figure, all-wheel drive optimal control + ESO is the method of the present invention. It can be seen from the figure that the control amount and output overshoot of the method of the present invention are the smallest, and the tracking effect is the best.

[0104] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A fuel cell intake system control method based on high-order all-wheel drive, characterized in that: It includes: A dynamic model of the fuel cell intake system is constructed, and a state space model of the dynamic model is obtained; the expression is: Where: x1 = ω cp , is the motor angular velocity of the air compressor in the fuel cell intake system, x2=P sm , is the air pressure of the cathode intake manifold in the fuel cell intake system, x3=P ca , is the cathode pressure of the fuel cell stack in the fuel cell intake system, x4=θ, is the throttle opening in the fuel cell intake system, ξ is the known current disturbance, h(x1,x2)=W cp , is the mass flow rate of air at the outlet of the air compressor, u1 is the air compressor voltage, u2=θ * , is the throttle opening instruction, · is the derivative, b1 is the first state parameter, b2 is the second state parameter, b3 is the third state parameter, b4 is the fourth state parameter, b5 is the fifth state parameter, b6 is the sixth state parameter, b7 is the seventh state parameter, b8 is the eighth state parameter, b9 is the ninth state parameter, b 10 is the tenth state parameter, b 11 is the eleventh state parameter, b 12 is the twelfth state parameter; An initial high-order all-wheel drive model is constructed based on the state space model; the expression is: Where: T is the transpose, x is the state vector, x = [x1, x2, x3, x4], L 12 =0,L 21 =0, Adding unknown disturbances to the initial high-order all-wheel drive model, a high-order all-wheel drive optimal control model is obtained; the expression is: Where: is the first unknown disturbance, is the second unknown disturbance, 0 to 1 represents the 0th and 1st order derivatives; A control law is constructed based on the high-order all-wheel drive optimal control model, and a fuel cell intake system is controlled based on the control law.

2. The fuel cell intake system control method based on high-level all-wheel drive according to claim 1 is characterized in that: The expression of the kinetic model is: Where: J cp is the motor moment of inertia, t is time, τ cm is the motor driving torque, τ cp is the load torque of the air compressor, R is the gas constant of air, T cp is the gas temperature inside the pipe, V sm is the volume of the gas supply pipeline, M a is the molar mass of the gas, W sm is the mass flow rate of the gas supply pipeline, T fc is the stack temperature, V ca is the volume of the cathode of the battery stack, W ca,out is the cathode outlet flow rate, is the molar mass of oxygen, is the oxygen flow rate participating in the reaction, T tr is the valve response time constant.

3. The fuel cell intake system control method based on high-level all-wheel drive according to claim 1 is characterized in that: b3=T atm , b 12 =T tr , η cm , k t , k v and R cm is the motor constant, C p is the specific heat capacity of gas, T atm is the atmospheric temperature, η cp is the maximum efficiency of the air compressor, γ is the air ratio, R a is the air gas constant, k sm is the outlet flow coefficient of the construction period pipeline, T st is the stack temperature, n cell is the number of batteries connected in series, F is the Faraday constant, C D,tr is the throttle valve discharge coefficient, A T,tr is the maximum throttling area.

4. The fuel cell intake system control method based on high-level all-wheel drive according to claim 1 is characterized in that: An unknown disturbance is added to the initial high-order all-wheel drive model to obtain a high-order all-wheel drive optimal control model, specifically: Construct an extended state observer; the expression is: Where: Φ 1,j is the first expansion state parameter, Φ 2,j is the second expansion state parameter, Φ 3,j is the third expansion state parameter, j = [1,2]; is Φ 1,j The observed value of is Φ 2,j The observed value of is Φ 3,j The observed value of β 1,j is the first observer gain vector, β 2,j is the second observer gain vector, β 3,j is the third observer gain vector; Input y1=x2 into the extended state observer and we get Input y2=x3 into the extended state observer, and we get Add to the initial high-order all-wheel drive model and The high-order all-wheel drive optimal control model is obtained.

5. The fuel cell intake system control method based on high-level all-wheel drive according to claim 4 is characterized in that: A control law is constructed based on the high-order all-wheel drive optimal control model, and a fuel cell intake system is controlled based on the control law, including: make i∈{2,3}; is the ideal state variable; The high-order all-wheel drive optimal control model is converted into a linear state to obtain a linear model; the expression is: Where: A E is the first parameter matrix, B E is the second parameter matrix; make Construct the objective function; the expression is: Where: J is the objective function, is a positive semidefinite matrix, is a positive definite matrix, and the objective function J aims to minimize the rate of change of the state variables; Based on the objective function, the Riccati algebraic equation is obtained to obtain a unique positive solution; A control law is constructed based on the unique positive solution, and a fuel cell intake system is controlled based on the control law.

6. The fuel cell intake system control method based on high-level all-wheel drive according to claim 5 is characterized in that: The control law expression is: Where: u is the controller output, P is the only positive solution, t is the time, f(x (0～1) )=f(z (0～1) ,t), is the lumped disturbance, representing and 7. The fuel cell intake system control method based on high-level all-wheel drive according to claim 5 is characterized in that:

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