Fuel cell air supply system based on vortex air compressor and control method thereof

Abstract

The invention provides a fuel cell air supply system based on a vortex air compressor and a control method thereof.The air supply system comprises a fuel cell stack and a controller, and an air filter, the vortex air compressor, an intercooler and a humidifier are sequentially arranged on an air inlet pipeline of the fuel cell stack in the air inlet path direction; a back pressure valve and a humidifier are sequentially arranged on the air outlet pipeline in the air outlet path direction; the controller is electrically connected with the vortex air compressor, the intercooler, the fuel cell stack and the back pressure valve, and a control method of the controller comprises an outer ring peroxide ratio control strategy based on the self-adaptive model prediction controller and further comprises an inner ring flow control strategy and a pressure cooperative control strategy based on the improved active disturbance rejection controller. The air system is reasonably arranged, the air supply amount and the pressure quickly respond to the load power request through cooperative control over key components of the system, the dynamic performance of the fuel cell is improved, and the service life of the fuel cell is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of vehicle fuel cell system control, in particular to a fuel cell air supply system based on a scroll air compressor and a control method thereof. Background Art

[0002] In the context of advocating energy conservation and environmental protection, the development of new energy vehicles has become a common choice for the automotive industry to cope with energy and environmental crises. Among them, proton exchange membrane fuel cells, as one of the main forms of hydrogen energy application, have the characteristics of cleanliness, pollution-free, high energy density, and high conversion efficiency, and have broad application prospects in the automotive field. The working principle of fuel cells is to generate electricity through the chemical reaction of hydrogen and oxygen. For different working currents, the air compressor in the fuel cell system needs to adapt to different flow rates and pressures to ensure reliability of use.

[0003] Due to the performance requirements of new energy vehicles themselves, there are corresponding requirements for their air compressors, such as small weight and space occupied, high conversion rate, etc., and at the same time, the stability of performance under various complex conditions must be met. Therefore, the superiority of the scroll air compressor is highlighted. In addition, effective control of the pressure and flow of the air supply system is the key to improving the efficiency and reliability of the fuel cell system. If the gas supply is insufficient, that is, the stack is "hungry", the output power of the stack will be reduced, and even the proton exchange membrane will be burned. If the gas supply is excessive, it will not only lead to an increase in parasitic power, but even cause safety accidents due to excessive gas pressure inside the stack. Designing an effective air supply system control strategy allows the gas supply to quickly respond to the load power request and maintain the stability of the reaction gas pressure in the stack, which is of great significance to improving the efficiency of fuel cells and extending their service life. Summary of the invention

[0004] The present invention proposes a fuel cell air supply system based on a scroll air compressor and a control method thereof, which can implement an effective control strategy for the air supply system so that the air supply volume quickly responds to the load power request and maintains the stability of the reaction gas pressure in the fuel cell stack.

[0005] The present invention adopts the following technical solutions.

[0006] A fuel cell air supply system based on a scroll air compressor, characterized in that: the air supply system comprises a fuel cell stack (5) and a controller (7); an air intake pipeline of the fuel cell stack is provided with an air filter (1), a scroll air compressor (2), an intercooler (3), and a humidifier (4) in sequence in the direction of the air intake path; and an air outlet pipeline is provided with a back pressure valve (6) and a humidifier (4) in sequence in the direction of the air outlet path;

[0007] The controller is electrically connected to the scroll air compressor, the intercooler, the fuel cell stack, and the back pressure valve respectively. The control method of the controller includes an outer loop excess oxygen ratio control strategy based on an adaptive model predictive controller, and also includes an inner loop flow control strategy and a pressure coordinated control strategy based on an improved anti-disturbance controller.

[0008] The air filter is used to filter foreign matter in the air input from the outside; the scroll air compressor is used to receive the filtered air output from the air filter and pressurize it to form compressed gas; the intercooler is used to receive the compressed gas output from the scroll air compressor and perform heat exchange so that the temperature of the compressed gas is within the applicable temperature range of the fuel cell stack; the fuel cell stack is used to receive the compressed gas after heat exchange output from the intercooler; and the back pressure valve is used to discharge the compressed gas passing through the fuel cell stack.

[0009] The control method of the fuel cell air supply system based on the scroll air compressor is used for the fuel cell air supply system based on the scroll air compressor described above. The fuel cell stack temperature is maintained under ideal conditions, the proton exchange membrane is fully humidified, and the supply of hydrogen meets the system control requirements. The fuel cell air supply system model based on the scroll air compressor is:

[0010]

[0011] Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sat Saturated water vapor partial pressure, P sm is the intake manifold pressure, P rm is the outlet pipe pressure, R is the air gas constant, T st is the stack temperature, χ O2 is the proportion of oxygen in the air, ω ca is the cathode inlet air humidity, M air is the molar mass of air, V ca is the cathode channel volume, k ca,in is the cathode inlet flow coefficient, k ca,out is the cathode outlet flow coefficient, T cp,out is the outlet temperature of the scroll compressor, W cp (n,ε) is the fitted gas mass flow rate at the outlet of the scroll compressor, W rm,out is the gas mass flow rate in the outlet pipe, W sm,out is the gas mass flow rate at the outlet of the intake pipe, m sm is the gas mass in the intake duct, ω cp is the main shaft speed of the scroll compressor, τ cm is the scroll compressor motor driving torque, τ cp is the load torque of the scroll air compressor motor.

[0012] The control method performs coordinated control of flow and pressure on the fuel cell air supply system under step current conditions. When a polynomial is used to fit the outlet mass flow of the scroll air compressor, the outlet mass flow of the scroll air compressor is expressed as:

[0013]

[0014] The design of the outer loop excess oxygen ratio control strategy based on the adaptive model predictive controller mainly includes the following steps: Step S11, taking the excess oxygen ratio of the fuel cell stack as the output, the outlet mass flow rate of the scroll air compressor and the outlet pipe pressure as the control quantity, simplifying the fuel cell air supply system model to obtain the system state space equation required by the outer loop control strategy;

[0015] Step S12, using the fuel cell operating current as a scheduling parameter, combining the system state matrix, the control matrix, etc. to construct an interpolation grid and a scheduling space of the system model matrix, and obtaining a global linear variable parameter LPV model of the air supply system;

[0016] Step S13, discretizing the LPV model, and establishing a system adaptive model predictive controller AMPC by combining the constraints of input, input change rate and output with the designed objective function;

[0017] Step S14, reconstructing the output flow and pressure reference values ​​of the inner loop improved active disturbance rejection controller according to the scroll air compressor output flow and intake manifold pressure trajectory planned by LPV-AMPC;

[0018] The design of the inner loop flow and pressure coordinated control strategy based on the improved active disturbance rejection controller ADRC mainly includes the following steps:

[0019] Step S21, constructing a second-order tracking differentiator TD to extract differential signals of the scroll air compressor output flow and the intake manifold pressure, and tracking the reference trajectory input by the outer ring LPV-AMPC;

[0020] Step S22, constructing an extended state observer ESO and taking the scroll air compressor voltage and back pressure valve opening input u and the scroll air compressor flow and intake manifold pressure output y as ESO input signals, and introducing a new disturbance state variable z3 to accurately estimate the total disturbance in the air compressor system;

[0021] Step S23: Use the error feedback control rate NLSEF to compensate and eliminate the disturbance in real time, calculate the scroll air compressor input voltage and the back pressure valve opening, and finally act on the air supply system.

[0022] The system state space equation required by the outer loop peroxygen ratio control strategy defined in step S11 is expressed as:

[0023]

[0024] Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sm is the intake manifold pressure, W cp is the mass flow rate at the outlet of the scroll compressor, P rm is the outlet pipe pressure, λ O2 is the peroxygen ratio, I st is the stack current, which is a measurable disturbance.

[0025] In step S12, the LPV model obtains the local dynamic characteristics of the system in the full working range according to the linear model parameters of the fuel cell air supply system under different working conditions, and takes the fuel cell working current I st The state space form of the LPV model as a scheduling parameter is as follows:

[0026]

[0027] Y=C(p)X+D u (p)U+D d (p)d

[0028] Among them, A(p), B(p), C(p), D(p)) are system matrices parameterized by the scheduling parameter vector p. The discretization model in step S13 is expressed as:

[0029]

[0030] Given the system constraints:

[0031]

[0032] Among them, u(k) refers to the control quantity, which is the mass flow rate at the outlet of the scroll air compressor and the outlet pipe pressure, Δu(k) refers to the change value of the control quantity, and y b (k) refers to the output value, i.e., the excess oxygen ratio;

[0033] The objective function:

[0034] J(x(k),ΔU(k))=||Γ y (Y p,c (k+1|k)-R(k+1))|| 2 +||Γ u ΔU(k)∣∣ 2

[0035] Among them, Γ y and Γ u is the weight matrix of the optimization problem, and R(k+1) is the reference output matrix.

[0036] The second-order tracking differentiator in step S21 is constructed as follows:

[0037]

[0038] Among them, ν 0,1 and ν 0,2 is the reference trajectory of the scroll compressor mass flow and intake manifold pressure dynamically output by the outer loop LPV-AMPC, ν 1,i represents the input signal ν 0,i The tracking signal, ν 2,i Indicates ν 1,i The first order differential of . 0,il It is an adjustment parameter used to control the tracking speed, h0 represents the filter factor;

[0039] The calculation formula of the nonlinear piecewise function fhan is:

[0040]

[0041] a,ξ0 are given by the following equation:

[0042]

[0043] The extended state observer in step S22 is expressed as:

[0044]

[0045] Among them, z 1,i and z 2,i Tracking and estimating the output signals of the scroll compressor mass flow and intake manifold pressure; and z 3,i is the estimated total disturbance; b1 and b2 are compensation coefficients; L i =[L 1,i L 2,i L 3,i ] T is the parameter that determines the output error correction gain; l(ε) is the nonlinear function of the improved ADRC;

[0046] After introducing the ESO bandwidth ω0, the ESO gain is calculated as:

[0047]

[0048] The nonlinear function of the improved ADRC is:

[0049]

[0050] Among them, nfal(·) represents the designed nonlinear smooth function, α is the nonlinear factor, δ is the filtering factor, s1 and s2 are weighting factors, The nonlinear error feedback control law of the pressure control and flow control in step S23 is expressed as:

[0051]

[0052] Among them, k 1,i represents the gain of the tracking signal, k 2,i Represents the gain of the tracking differential signal.

[0053] The calculation formula of the scroll air compressor input voltage and the back-opening valve opening in step S23 is:

[0054]

[0055] The present invention has the following beneficial effects:

[0056] 1. The present invention rationally arranges the air system and cascade-couples the model predictive control with predictive capability and system state constraints and can achieve stable control effect, with the self-disturbance rejection control with the capability of eliminating internal coupling, external interference and rapid response, to design a coordinated control strategy for the flow and pressure of the air supply system. The air supply volume and pressure can quickly respond to load power requests, thereby improving the working efficiency and life of the fuel cell.

[0057] 2. The outer loop model predictive control strategy proposed in the present invention aims at the nonlinear characteristics of the fuel cell air supply system and the problem of local model errors in the linearized model. Through the linearized model of the multi-stable working points of the air supply system, a global linear variable parameter model of the system is established, and an adaptive model predictive controller is designed based on this, and the flow and pressure reference values ​​of the improved anti-disturbance controller of the inner loop are reconstructed;

[0058] 3. The inner-loop anti-disturbance control strategy proposed in the present invention aims to solve the problem that traditional nonlinear functions are prone to oscillation at segmentation points. A nonlinear smooth function with differentiable segmentation points is designed to improve control stability. At the same time, improved ADRC is designed for the scroll air compressor flow and intake manifold pressure control respectively, converting the system's coordinated control problem into an interference suppression problem. Compared with traditional control strategies, both flow and pressure can better follow the reference trajectory and their mutual influence is weakened. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0060] Attached Figure 1 is a schematic structural diagram of the fuel cell air supply system of the present invention;

[0061] Attached Figure 2 is a framework diagram of a control method for a fuel cell air supply system of the present invention;

[0062] Attached Figure 3 is a flow rate and pressure coordinated control result diagram of the fuel cell air supply system of the present invention;

[0063] In the figure: 1- air filter, 2- scroll air compressor, 3- intercooler, 4- humidifier, 5- fuel cell stack, 6- back pressure valve, 7- controller. DETAILED DESCRIPTION

[0064] A fuel cell air supply system based on a scroll air compressor, characterized in that: the air supply system comprises a fuel cell stack 5 and a controller 7, an air intake pipeline of the fuel cell stack is provided with an air filter 1, a scroll air compressor 2, an intercooler 3, and a humidifier 4 in sequence in the direction of the air intake path, and an air outlet pipeline is provided with a back pressure valve 6 and a humidifier 4 in sequence in the direction of the air outlet path;

[0065] The controller 7 is electrically connected to the scroll air compressor, intercooler, fuel cell stack, and back pressure valve respectively. The control method of the controller includes an outer loop peroxygen ratio control strategy based on an adaptive model predictive controller, and also includes an inner loop flow control strategy and a pressure coordinated control strategy based on an improved anti-disturbance controller.

[0066] The air filter is used to filter foreign matter in the air input from the outside; the scroll air compressor is used to receive the filtered air output from the air filter and pressurize it to form compressed gas; the intercooler is used to receive the compressed gas output from the scroll air compressor and perform heat exchange so that the temperature of the compressed gas is within the applicable temperature range of the fuel cell stack; the fuel cell stack is used to receive the compressed gas after heat exchange output from the intercooler; and the back pressure valve is used to discharge the compressed gas passing through the fuel cell stack.

[0067] The control method of the fuel cell air supply system based on the scroll air compressor is used for the fuel cell air supply system based on the scroll air compressor described above. The fuel cell stack temperature is maintained under ideal conditions, the proton exchange membrane is fully humidified, and the supply of hydrogen meets the system control requirements. The fuel cell air supply system model based on the scroll air compressor is:

[0068]

[0069] Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sat Saturated water vapor partial pressure, P sm is the intake manifold pressure, P rm is the outlet pipe pressure, R is the air gas constant, T stis the stack temperature, χ O2 is the proportion of oxygen in the air, ω ca is the cathode inlet air humidity, M air is the molar mass of air, V ca is the cathode channel volume, k ca,in is the cathode inlet flow coefficient, k ca,out is the cathode outlet flow coefficient, T cp,out is the outlet temperature of the scroll compressor, W cp (n,ε) is the fitted gas mass flow rate at the outlet of the scroll compressor, W rm,out is the gas mass flow rate in the outlet pipe, W sm,out is the gas mass flow rate at the outlet of the intake pipe, m sm is the gas mass in the intake duct, ω cp is the main shaft speed of the scroll compressor, τ cm is the scroll compressor motor driving torque, τ cp is the load torque of the scroll air compressor motor.

[0070] The control method performs coordinated control of flow and pressure on the fuel cell air supply system under step current conditions. When a polynomial is used to fit the outlet mass flow of the scroll air compressor, the outlet mass flow of the scroll air compressor is expressed as:

[0071]

[0072] The design of the outer loop excess oxygen ratio control strategy based on the adaptive model predictive controller mainly includes the following steps: Step S11, taking the excess oxygen ratio of the fuel cell stack as the output, the outlet mass flow rate of the scroll air compressor and the outlet pipe pressure as the control quantity, simplifying the fuel cell air supply system model to obtain the system state space equation required by the outer loop control strategy;

[0073] Step S12, using the fuel cell operating current as a scheduling parameter, combining the system state matrix, the control matrix, etc. to construct an interpolation grid and a scheduling space of the system model matrix, and obtaining a global linear variable parameter LPV model of the air supply system;

[0074] Step S13, discretizing the LPV model, and establishing a system adaptive model predictive controller AMPC by combining the constraints of input, input change rate and output with the designed objective function;

[0075] Step S14, reconstructing the output flow and pressure reference values ​​of the inner loop improved active disturbance rejection controller according to the scroll air compressor output flow and intake manifold pressure trajectory planned by LPV-AMPC;

[0076] The design of the inner loop flow and pressure coordinated control strategy based on the improved active disturbance rejection controller ADRC mainly includes the following steps:

[0077] Step S21, constructing a second-order tracking differentiator TD to extract differential signals of the scroll air compressor output flow and the intake manifold pressure, and tracking the reference trajectory input by the outer ring LPV-AMPC;

[0078] Step S22, constructing an extended state observer ESO and taking the scroll air compressor voltage and back pressure valve opening input u and the scroll air compressor flow and intake manifold pressure output y as ESO input signals, and introducing a new disturbance state variable z3 to accurately estimate the total disturbance in the air compressor system;

[0079] Step S23: Use the error feedback control rate NLSEF to compensate and eliminate the disturbance in real time, calculate the scroll air compressor input voltage and the back pressure valve opening, and finally act on the air supply system.

[0080] The system state space equation required by the outer loop peroxygen ratio control strategy defined in step S11 is expressed as:

[0081]

[0082] Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sm is the intake manifold pressure, W cp is the mass flow rate at the outlet of the scroll compressor, P rm is the outlet pipe pressure, λ O2 is the peroxygen ratio, I st is the stack current, which is a measurable disturbance.

[0083] In step S12, the LPV model obtains the local dynamic characteristics of the system in the full working range according to the linear model parameters of the fuel cell air supply system under different working conditions, and takes the fuel cell working current I st The state space form of the LPV model as a scheduling parameter is as follows:

[0084]

[0085] Y=C(p)X+D u (p)U+D d (p)d

[0086] Among them, A(p), B(p), C(p), D(p)) are system matrices parameterized by the scheduling parameter vector p. The discretization model in step S13 is expressed as:

[0087]

[0088] Given the system constraints:

[0089]

[0090] Among them, u(k) refers to the control quantity, which is the mass flow rate at the outlet of the scroll air compressor and the outlet pipe pressure, Δu(k) refers to the change value of the control quantity, and y b (k) refers to the output value, i.e., the excess oxygen ratio;

[0091] The objective function:

[0092] J(x(k),ΔU(k))=||Γ y (Y p,c (k+1|k)-R(k+1))|| 2 +||Γ u ΔU(k)∣∣ 2

[0093] Among them, Γ y and Γ u is the weight matrix of the optimization problem, and R(k+1) is the reference output matrix.

[0094] The second-order tracking differentiator in step S21 is constructed as follows:

[0095]

[0096] Among them, ν 0,1 and ν 0,2 is the reference trajectory of the scroll compressor mass flow and intake manifold pressure dynamically output by the outer loop LPV-AMPC, ν 1,i represents the input signal ν 0,i The tracking signal, ν 2,i Indicates ν 1,i The first order differential of . 0,il It is an adjustment parameter used to control the tracking speed, h0 represents the filter factor;

[0097] The calculation formula of the nonlinear piecewise function fhan is:

[0098]

[0099] a,ξ0 are given by the following equation:

[0100]

[0101] The extended state observer in step S22 is expressed as:

[0102]

[0103] Among them, z 1,i and z 2,iTracking and estimation of the output signals of the scroll compressor mass flow and intake manifold pressure; i and z 3,i is the estimated total disturbance; b1 and b2 are compensation coefficients; L i =[L 1,i L 2,i L 3,i ] T is the parameter that determines the output error correction gain; l(ε) is the nonlinear function of the improved ADRC;

[0104] After introducing the ESO bandwidth ω0, the ESO gain is calculated as:

[0105]

[0106] The nonlinear function of the improved ADRC is:

[0107]

[0108] Among them, nfal(·) represents the designed nonlinear smooth function, α is the nonlinear factor, δ is the filtering factor, s1 and s2 are weighting factors, The nonlinear error feedback control law of the pressure control and flow control in step S23 is expressed as:

[0109]

[0110] Among them, k 1,i represents the gain of the tracking signal, k 2,i Represents the gain of the tracking differential signal.

[0111] The calculation formula of the scroll air compressor input voltage and the back-opening valve opening in step S23 is:

[0112]

[0113] Example:

[0114] The detailed descriptions of the following embodiments are exemplary and are intended to provide a more detailed description of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by researchers in the technical field to which the present application belongs.

[0115] This example provides a fuel cell air supply system based on a scroll air compressor and a control method thereof. In this embodiment, Figure 1 , Figure 2As shown, the system includes a fuel cell stack 5 and a controller 7. The intake pipeline of the fuel cell stack is connected to an air filter 1, a vortex air compressor 2, an intercooler 3, and a humidifier 4 in sequence from far to near, and the outlet pipeline is connected to a back pressure valve 6 and a humidifier 4 in sequence from far to near; the controller 7 is electrically connected to the vortex air compressor 2, the intercooler 3, the fuel cell stack 5, and the back pressure valve 6 respectively. The control method consists of two parts, including an outer loop peroxygen ratio control based on an adaptive model predictive controller and an inner loop flow and pressure coordinated control based on an improved self-disturbance rejection controller. The present invention reasonably arranges the air system and controls the key components of the system so that the air supply quickly responds to the load power request, while accurately controlling the pressure, which helps to improve the dynamic performance of the fuel cell and extend its service life. .

[0116] In this embodiment, the air filter 1 is used to filter foreign matter in the air input from the outside;

[0117] The scroll air compressor 2 is used to receive the filtered air output from the air filter and pressurize it to form compressed gas;

[0118] The intercooler 3 is used to receive the compressed gas output from the air compressor and perform heat exchange so that the temperature of the compressed gas is within the applicable temperature range of the fuel cell stack;

[0119] The fuel cell stack 5 is used to receive the compressed gas after heat exchange output from the intercooler;

[0120] The back pressure valve 6 is used to discharge the compressed gas passing through the fuel cell stack;

[0121] In this embodiment, assuming that the temperature of the fuel cell stack is maintained under ideal conditions, the proton exchange membrane is fully humidified, and the supply of hydrogen meets the system control requirements, a fuel cell air supply system model based on a scroll air compressor is constructed as follows:

[0122]

[0123] Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sat Saturated water vapor partial pressure, P sm is the intake manifold pressure, P rm is the outlet pipe pressure, R is the air gas constant, T st is the stack temperature, χ O2 is the proportion of oxygen in the air, ω ca is the cathode inlet air humidity, M air is the molar mass of air, V ca is the cathode channel volume, k ca,in is the cathode inlet flow coefficient, k ca,out is the cathode outlet flow coefficient, Tcp,out is the outlet temperature of the scroll compressor, W cp (n,ε) is the fitted gas mass flow rate at the outlet of the scroll compressor, W rm,out is the gas mass flow rate in the outlet pipeline, W sm,out is the gas mass flow rate at the outlet of the intake pipe, m sm is the gas mass in the intake duct, ω cp is the main shaft speed of the scroll compressor, τ cm is the scroll compressor motor driving torque, τ cp is the load torque of the scroll air compressor motor.

[0124] In this embodiment, a polynomial is used to fit the outlet mass flow rate of the scroll air compressor, and the outlet mass flow rate of the scroll air compressor is expressed as:

[0125]

[0126] Among them, ε c Indicates the compression ratio of the scroll compressor, ω cp It is expressed as the rotation speed of the scroll air compressor. c00, c10, c20, c01, c11 and c02 are the fitting coefficients of the static model of the scroll air compressor.

[0127] In this embodiment, the outer loop peroxygen ratio control strategy design based on the adaptive model predictive controller mainly includes the following steps:

[0128] Step S11, using the excess oxygen ratio of the fuel cell stack as the output, and the outlet mass flow rate of the scroll air compressor and the outlet pipe pressure as the control variables to simplify the fuel cell air supply system model and obtain the system state space equation required by the outer loop control strategy;

[0129] Step S12, using the fuel cell operating current as a scheduling parameter, combining the system state matrix, the control matrix, etc. to construct an interpolation grid and a scheduling space of the system model matrix, and obtaining a global linear variable parameter (LPV) model of the air supply system;

[0130] Step S13, discretizing the LPV model, and establishing a system adaptive model predictive controller (AMPC) by combining the constraints of input, input change rate and output with the designed objective function;

[0131] Step S14, reconstructing the output flow and pressure reference values ​​of the inner loop improved active disturbance rejection controller according to the scroll air compressor output flow and intake manifold pressure trajectory planned by LPV-AMPC.

[0132] The design of the inner loop flow and pressure coordinated control strategy based on the improved active disturbance rejection controller (ADRC) mainly includes the following steps:

[0133] Step S21, constructing a second-order tracking differentiator (TD) to extract differential signals of the scroll compressor output flow and the intake manifold pressure, and tracking the reference trajectory of the outer ring LPV-AMPC input;

[0134] Step S22, construct an extended state observer (ESO) and use the scroll compressor voltage and back pressure valve opening input u and the scroll compressor flow and intake manifold pressure output y as ESO input signals, and introduce a new disturbance state variable z3 to accurately estimate the total disturbance in the air compressor system.

[0135] Step S23: Use the error feedback control rate (NLSEF) to compensate and eliminate the disturbance in real time, calculate the scroll air compressor input voltage and the back pressure valve opening, and finally act on the air supply system.

[0136] In this embodiment, the system state space equation required by the outer loop peroxygen ratio control strategy defined in step S11 is expressed as:

[0137]

[0138] Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sm is the intake manifold pressure, W cp is the mass flow rate at the outlet of the scroll compressor, P rm is the outlet pipe pressure, λ O2 is the peroxygen ratio, I st is the stack current, which is a measurable disturbance.

[0139] In this embodiment, the LPV model in step S12 needs to obtain the local dynamic characteristics of the system in the full working range according to the linear model parameters of the fuel cell air supply system under different working conditions. st The state space form of the LPV model as a scheduling parameter is as follows:

[0140]

[0141] Y=C(I st )X+D u (I st )U+D d (I st )d

[0142] Among them, A(I st )、B(I st )、C(I st )、D(I st )) is determined by the scheduling parameter I st Parameterized system matrix.

[0143] In this embodiment, the discretization model in step S13 is expressed as:

[0144]

[0145] Given the system constraints:

[0146]

[0147] Among them, u(k) refers to the control quantity, which is the mass flow rate at the outlet of the scroll air compressor and the outlet pipe pressure, Δu(k) refers to the change value of the control quantity, and y b (k) refers to the output value, i.e., the excess oxygen ratio;

[0148] The objective function:

[0149] J(x(k),ΔU(k))=||Γ y (Y p,c (k+1|k)-R(k+1))|| 2 +||Γ u ΔU(k)∣∣ 2

[0150] Among them, Γ y and Γ u is the weight matrix of the optimization problem, and R(k+1) is the reference output matrix

[0151] In this embodiment, the second-order tracking differentiator in step S21 is constructed as follows:

[0152]

[0153] Among them, ν 0,1 and ν 0,2 is the reference trajectory of the scroll compressor mass flow and intake manifold pressure dynamically output by the outer loop LPV-AMPC, ν 1,i represents the input signal ν 0,i The tracking signal, ν 2,i Indicates ν 1,i The first order differential of . 0,il is an adjustment parameter used to control the tracking speed, h0 represents a filtering factor; in this embodiment, the calculation formula of the nonlinear piecewise function fhan is:

[0154]

[0155] a,ξ0 are given by the following equation:

[0156]

[0157] In this embodiment, the extended state observer in step S22 is expressed as:

[0158]

[0159] Among them, z 1,i and z 2,i Tracking and estimating the output signals of the scroll compressor mass flow and intake manifold pressure; and z 3,i is the estimated total disturbance; b1 and b2 are compensation coefficients; l(ε) is the nonlinear function of the improved ADRC; L i =[L 1,i L 2,i L 3,i ] T is a parameter that determines the output error correction gain. In this embodiment, the ESO bandwidth ω0 is introduced and the ESO gain is calculated as:

[0160]

[0161] The nonlinear function of the improved ADRC is:

[0162]

[0163] Among them, nfal(·) represents the designed nonlinear smooth function, α is the nonlinear factor, δ is the filtering factor, and s1 and s2 are weighting factors:

[0164]

[0165] In this embodiment, the nonlinear error feedback control law of the pressure control and flow control in step S23 is expressed as:

[0166]

[0167] Among them, k 1,i represents the gain of the tracking signal, k 2,i Represents the gain of the tracking differential signal. In this embodiment, the bandwidth ω is introduced c ,but In this embodiment, the calculation formula of the scroll air compressor input voltage and the back-opening valve opening in step S23 is:

[0168] In this embodiment, the control method is used to coordinate the flow and pressure of the fuel cell air supply system under the step current condition. The control result is as follows: Figure 3 As shown (the comparison controller is the traditional single MPC controller).

[0169] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A fuel cell air supply system based on a scroll air compressor, characterized in that: The air supply system comprises a fuel cell stack (5) and a controller (7); an air filter (1), a scroll air compressor (2), an intercooler (3), and a humidifier (4) are provided in sequence on the air intake pipeline of the fuel cell stack in the air intake direction; and a back pressure valve (6) and a humidifier (4) are provided in sequence on the air outlet pipeline in the air outlet direction; The controller is electrically connected to the scroll air compressor, the intercooler, the fuel cell stack, and the back pressure valve respectively. The control method of the controller includes an outer loop excess oxygen ratio control strategy based on an adaptive model predictive controller, and also includes an inner loop flow control strategy and a pressure coordinated control strategy based on an improved anti-disturbance controller.

2. The fuel cell air supply system based on a scroll air compressor according to claim 1, characterized in that: The air filter is used to filter foreign matter in the air input from the outside; the scroll air compressor is used to receive the filtered air output from the air filter and pressurize it to form compressed gas; The intercooler is used to receive the compressed gas output from the scroll air compressor and perform heat exchange so that the temperature of the compressed gas is within the applicable temperature range of the fuel cell stack; the fuel cell stack is used to receive the compressed gas output from the intercooler after heat exchange; The back pressure valve is used to discharge the compressed gas passing through the fuel cell stack.

3. A control method for a fuel cell air supply system based on a scroll air compressor, used in the fuel cell air supply system based on a scroll air compressor in claim 2, characterized in that: When the temperature of the fuel cell stack is kept under ideal conditions, the proton exchange membrane is fully humidified, and the supply of hydrogen meets the system control requirements, the fuel cell air supply system model based on the scroll air compressor is: Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sat Saturated water vapor partial pressure, P sm is the intake manifold pressure, P rm is the outlet pipe pressure, R is the air gas constant, T st is the stack temperature, χ O2 is the proportion of oxygen in the air, ω ca is the cathode inlet air humidity, M air is the molar mass of air, V ca is the cathode channel volume, k ca,in is the cathode inlet flow coefficient, k ca,out is the cathode outlet flow coefficient, T cp,out is the outlet temperature of the scroll compressor, W cp (n,ε) is the fitted gas mass flow rate at the outlet of the scroll compressor, W rm,out is the gas mass flow rate in the outlet pipe, W sm,out is the gas mass flow rate at the outlet of the intake pipe, m sm is the gas mass in the intake duct, ω cp is the main shaft speed of the scroll compressor, τ cm is the scroll compressor motor driving torque, τ cp is the load torque of the scroll air compressor motor.

4. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 3, characterized in that: The control method performs coordinated control of flow and pressure in the fuel cell air supply system. When a polynomial is used to fit the outlet mass flow of the scroll air compressor, the outlet mass flow of the scroll air compressor is expressed as: The design of the outer loop overoxygen ratio control strategy based on the adaptive model predictive controller mainly includes the following steps: Step S11, using the excess oxygen ratio of the fuel cell stack as the output, and the outlet mass flow rate of the scroll air compressor and the outlet pipe pressure as the control variables to simplify the fuel cell air supply system model and obtain the system state space equation required by the outer loop control strategy; Step S12, using the fuel cell operating current as a scheduling parameter, combining the system state matrix, the control matrix, etc. to construct an interpolation grid and a scheduling space of the system model matrix, and obtaining a global linear variable parameter LPV model of the air supply system; Step S13, discretizing the LPV model, and establishing a system adaptive model predictive controller AMPC by combining the constraints of input, input change rate and output with the designed objective function; Step S14, reconstructing the output flow and pressure reference values ​​of the inner loop improved active disturbance rejection controller according to the scroll air compressor output flow and intake manifold pressure trajectory planned by LPV-AMPC; The design of the inner loop flow and pressure coordinated control strategy based on the improved active disturbance rejection controller ADRC mainly includes the following steps: Step S21, constructing a second-order tracking differentiator TD to extract differential signals of the scroll air compressor output flow and the intake manifold pressure, and tracking the reference trajectory input by the outer ring LPV-AMPC; Step S22, constructing an extended state observer ESO and taking the scroll air compressor voltage and back pressure valve opening input u and the scroll air compressor flow and intake manifold pressure output y as ESO input signals, and introducing a new disturbance state variable z3 to accurately estimate the total disturbance in the air compressor system; Step S23: Use the error feedback control rate NLSEF to compensate and eliminate the disturbance in real time, calculate the scroll air compressor input voltage and the back pressure valve opening, and finally act on the air supply system.

5. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 4, characterized in that: The system state space equation required by the outer loop peroxygen ratio control strategy defined in step S11 is expressed as: Among them, P O2 is the partial pressure of oxygen, P N2 is the nitrogen partial pressure, P sm is the intake manifold pressure, W cp is the mass flow rate at the outlet of the scroll compressor, P rm is the outlet pipe pressure, λ O2 is the peroxygen ratio, I st is the stack current, which is a measurable disturbance.

6. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 4, characterized in that: In step S12, the LPV model obtains the local dynamic characteristics of the system in the full working range according to the linear model parameters of the fuel cell air supply system under different working conditions, and takes the fuel cell working current I st The state space form of the LPV model as a scheduling parameter is as follows: Y=C(p)X+D u (p)U+D d (p)d Among them, A(p), B(p), C(p), D(p)) are system matrices parameterized by the scheduling parameter vector p.

7. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 4, characterized in that: The discretization model in step S13 is expressed as: Given the system constraints: Among them, u(k) refers to the control quantity, which is the mass flow rate at the outlet of the scroll air compressor and the outlet pipe pressure, Δu(k) refers to the change value of the control quantity, and y b (k) refers to the output value, i.e., the excess oxygen ratio; The objective function: J(x(k),ΔU(k))=∣∣Γ y (Y p,c (k+1∣k)-R(k+1))∣∣ 2 +∣∣Γ u ΔU(k)∣∣ 2 Among them, Γ y and Γ u is the weight matrix of the optimization problem, and R(k+1) is the reference output matrix.

8. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 4, characterized in that: The second-order tracking differentiator in step S21 is constructed as follows: Among them, ν 0,1 and ν 0,2 is the reference trajectory of the scroll compressor mass flow and intake manifold pressure dynamically output by the outer loop LPV-AMPC, ν 1,i represents the input signal ν 0,i The tracking signal, ν 2,i Indicates ν 1,i The first order differential of . 0,il It is an adjustment parameter used to control the tracking speed, h0 represents the filter factor; The calculation formula of the nonlinear piecewise function fhan is: a,ξ0 are given by the following equation:

9. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 4, characterized in that: The extended state observer in step S22 is expressed as: Among them, z 1,i and z 2,i Tracking and estimating the output signals of the scroll air compressor mass flow and intake manifold pressure; and z 3,i is the estimated total disturbance; b1 and b2 are compensation coefficients; L i =[L 1,i L 2,i L 3,i ] T is the parameter that determines the output error correction gain; l(ε) is the nonlinear function of the improved ADRC; After introducing the ESO bandwidth ω0, the ESO gain is calculated as: The nonlinear function of the improved ADRC is: Among them, nfal(·) represents the designed nonlinear smooth function, α is the nonlinear factor, δ is the filter factor, s1 and s2 are weighting factors, 10. The control method of the fuel cell air supply system based on the scroll air compressor according to claim 4, characterized in that: The nonlinear error feedback control law of the pressure control and flow control in step S23 is expressed as: Among them, k 1,i represents the gain of the tracking signal, k 2,i Represents the gain of the tracking differential signal. The calculation formula of the scroll air compressor input voltage and the back-opening valve opening in step S23 is:

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