Fuel cell system operation method, control device and storage medium

Abstract

The present application relates to an operation method, a control device and a storage medium of a fuel cell system. The operation method of the fuel cell system, the fuel cell system at least includes a connected fuel cell and a DC / DC converter, the DC / DC converter is used to receive the output current of the fuel cell and adjust it, the method includes: constructing a relationship function between the operation efficiency of the fuel cell system and the output current of the fuel cell, the relationship function includes multiple parameters to be identified; according to the data sets of the fuel cell system at multiple times, the values ​​of multiple parameters to be identified are obtained to obtain the current relationship function; according to the current relationship function, the maximum operation efficiency of the current fuel cell system is obtained, and the fuel cell system is controlled to operate at the maximum operation efficiency. The operation method of the fuel cell system can make the fuel cell system operate at the maximum efficiency to reasonably utilize energy.

Description

Technical Field

[0001] The present application relates to the field of fuel cells and automated control technology, and in particular to an operating method, a control device and a storage medium for a fuel cell system. Background Art

[0002] Energy has always been a prerequisite for the development of human society and economy. In recent years, with the continuous development of society, the depletion of oil resources and the increasingly serious climate environment, the power system industry is reorganizing renewable energy power generation as an alternative solution. Proton Exchange Membrane Fuel Cell (PEMFC) has received widespread attention and application in recent years due to its high efficiency and low emissions.

[0003] However, the efficiency characteristics of the fuel cell system are easily affected by many other factors, such as operating temperature, gas flow, ambient humidity, etc. If the operating efficiency of the fuel cell system is too low, it will lead to waste of hydrogen and oxygen, which is contrary to sustainable development. Therefore, controlling the output power of the fuel cell system to make the fuel cell system operate at the maximum efficiency point has become a key issue. Summary of the invention

[0004] Based on this, it is necessary to provide an operating method, a control device and a storage medium for a fuel cell system that can enable the fuel cell system to operate at maximum efficiency in response to the above technical problems.

[0005] A method for operating a fuel cell system, the fuel cell system comprising at least a connected fuel cell and an auxiliary machine of the fuel cell system, the auxiliary machine of the fuel cell system being used to receive an output current of the fuel cell and perform regulation, the method comprising:

[0006] Constructing a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes a plurality of parameters to be identified;

[0007] Acquire values ​​of a plurality of parameters to be identified according to data sets of a fuel cell system at a plurality of times to obtain a current relationship function;

[0008] According to the current relationship function, the maximum operating efficiency of the current fuel cell system is obtained, and the fuel cell system is controlled to operate at the maximum operating efficiency.

[0009] In one embodiment, obtaining values ​​of multiple parameters to be identified based on data sets of the fuel cell system at multiple times includes:

[0010] The data sets of the fuel cell system at multiple times are calculated by a recursive least squares parameter estimation algorithm to obtain the values ​​of multiple parameters to be identified.

[0011] In one embodiment, a recursive least squares parameter estimation algorithm is used to calculate a data set of a fuel cell system at multiple times, including:

[0012] Constructing a first recursive formula of a recursive least squares parameter estimation algorithm for a fuel cell system, the first recursive formula is used to characterize the recursive relationship between the value of the parameter to be identified at the kth moment and the value of the parameter to be identified at the k-1th moment, the output current of the fuel cell at multiple moments before the kth moment, and the maximum operating efficiency of the fuel cell system at multiple moments before the kth moment;

[0013] Calculation is performed according to the first recursive formula and data sets of the fuel cell system at multiple moments.

[0014] In one embodiment, the calculation is performed based on the first recursive formula and the data sets of the fuel cell system at multiple moments, including:

[0015] Generate a second recursive formula according to the forgetting factor and the first recursive formula;

[0016] Calculation is performed according to the second recursive formula and data sets of the fuel cell system at multiple moments.

[0017] In one embodiment, after obtaining the maximum operating efficiency of the current fuel cell according to the current relationship function, the method further includes:

[0018] Obtaining a reference current value output by the fuel cell corresponding to the maximum operating efficiency, and obtaining a control signal according to the reference current value;

[0019] Controlling the fuel cell system to operate at maximum operating efficiency includes:

[0020] The output current of the fuel cell is controlled to be equal to the reference current value according to the control signal, so that the fuel cell system operates at a maximum operating efficiency.

[0021] In one embodiment, the method further comprises:

[0022] Building a simulation model of a fuel cell system, the simulation model being configured with a relational function;

[0023] Obtaining a time-efficiency curve generated when the simulation model operates in response to a fluctuating load condition;

[0024] Analyze the effectiveness of relationship functions based on time-efficiency curves.

[0025] In one embodiment, analyzing the effectiveness of the relationship function according to the operation efficiency curve includes:

[0026] Obtaining the operating efficiency and the average value of the operating efficiency within a first preset time range in the time-efficiency curve;

[0027] When the difference between the operating efficiency and the mean of the operating efficiency is less than the first preset value, it is determined that the relationship function is valid.

[0028] A control device for operation of a fuel cell system, comprising:

[0029] A relationship function building module is used to build a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes a plurality of parameters to be identified;

[0030] A parameter identification module, which identifies the values ​​of multiple parameters to be identified according to the data sets of the fuel cell system at multiple times and uses a forgetting factor recursive least squares parameter estimation algorithm to obtain the current relationship function;

[0031] A maximum operating efficiency acquisition module, which acquires the maximum operating efficiency of the current fuel cell system according to the current relationship function, and controls the fuel cell system to operate according to the maximum operating efficiency;

[0032] The fuel cell system at least includes a connected fuel cell and an auxiliary machine of the fuel cell system, and the auxiliary machine of the fuel cell system is used to receive the output current of the fuel cell and adjust it.

[0033] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0034] A computer-readable storage medium stores a computer program, which implements the steps of the above method when executed by a processor.

[0035] The above-mentioned fuel cell system at least includes a connected fuel cell and an auxiliary machine of the fuel cell system, the auxiliary machine of the fuel cell system is used to receive the output current of the fuel cell and adjust it, and the operation method of the above-mentioned fuel cell system includes: constructing a relationship function between the operation efficiency of the fuel cell system and the output current of the fuel cell, the relationship function includes multiple parameters to be identified; obtaining the values ​​of multiple parameters to be identified according to the data sets of multiple moments of the fuel cell system to obtain the current relationship function; according to the current relationship function, obtaining the maximum operation efficiency of the current fuel cell system, so that the fuel cell system operates at the maximum operation efficiency. During the operation of the fuel cell system, the terminal voltage of the fuel cell will change with the change of parameters such as the flow rate of the injected gas, the pressure of the injected gas, the ambient temperature and humidity, and this change is nonlinear, which causes the maximum efficiency of the fuel cell to change with the change of system parameters. The present invention first establishes a relationship function between the operation efficiency of the fuel cell system and the output current of the fuel cell, and further obtains the current relationship function by collecting the historical parameter data set of the fuel cell system, and obtains the maximum value point of the fuel fuel cell operation efficiency according to the current relationship function, so that the fuel cell system will operate at the maximum efficiency, achieving the purpose of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 This is one of the flow charts of the operating method of a fuel cell system in one embodiment;

[0038] Figure 2 is an operating efficiency-current curve diagram of a fuel cell in one embodiment;

[0039] Figure 3 The operating efficiency-current experimental curve and fitting curve diagram of a fuel cell in one embodiment;

[0040] Figure 4 The second flowchart of the operating method of the fuel cell system in one embodiment;

[0041] Figure 5 The third flowchart of the operating method of the fuel cell system in one embodiment;

[0042] Figure 6 This is a fourth flow chart of an operating method of a fuel cell system in one embodiment;

[0043] Figure 7 This is a fifth flow chart of an operating method of a fuel cell system in one embodiment;

[0044] Figure 8 This is a sixth flow chart of a method for operating a fuel cell system in one embodiment;

[0045] Fig. 9 A schematic diagram of the topological structure of a fuel cell system in one embodiment;

[0046] Fig.10 A fuel cell model diagram in one embodiment;

[0047] Fig.11 A DC / DC converter model in one embodiment;

[0048] Fig.12 A DC load model in one embodiment;

[0049] Fig.13 A simulation model of a fuel cell system in one embodiment;

[0050] Fig.14 is a curve diagram of a DC load condition in one embodiment;

[0051] Fig.15 is an output current curve diagram of a fuel cell in one embodiment;

[0052] Fig.16 An efficiency curve diagram of a battery system in one embodiment;

[0053] Fig.17 FIG7 is a flow chart of a method for operating a fuel cell system in one embodiment;

[0054] Fig.18 FIG8 is a flow chart of an operating method of a fuel cell system in one embodiment;

[0055] Fig.19 It is a structural block diagram of a control device for a fuel cell operation method in one embodiment. DETAILED DESCRIPTION

[0056] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0058] It is to be understood that the terms "first", "second", etc. used in this application can be used in this article to describe various recursive formulas, but these recursive formulas are not limited by these terms. These terms are only used to distinguish the first recursive formula from another recursive formula.

[0059] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0060] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0061] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0062] In one embodiment, if Figure 1 As shown, a flow chart of an operating method of a fuel cell system is provided. The fuel cell system in this embodiment includes at least a connected fuel cell and an auxiliary machine of the fuel cell system. The auxiliary machine of the fuel cell system is used to receive the output current of the fuel cell and adjust it. The operating method of the fuel cell system in this embodiment includes steps S100 to S300.

[0063] Step S100 , constructing a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes a plurality of parameters to be identified.

[0064] From the definition of fuel cell efficiency, we can know that the efficiency of a fuel cell is equal to the ratio of the electrical energy generated by the fuel cell to the hydrogen energy consumed. Therefore, for a fuel cell composed of a battery stack, the efficiency formula of the fuel cell is as follows:

[0065]

[0066] Among them, η FC Represents the efficiency of the fuel cell stack, P H2 Represents the hydrogen energy consumed by a single fuel cell, P SFC Represents the electrical energy generated by a single fuel cell, V SFC It represents the terminal voltage of the output end of a single fuel cell in a fuel cell stack, I FC represents the output current of the fuel cell, ΔH HV It represents the energy released when hydrogen is burned completely and thoroughly, and F represents the Faraday constant. HV If the high calorific value is used for calculation, it can be taken as 141.9 MJ / kg, and if the low calorific value is used for calculation, it can be taken as 120.1 MJ / kg. The Faraday constant F is always equal to 96485 C / mol. In the present invention, the high calorific value is used when calculating the efficiency of the fuel cell system.

[0067] In actual fuel cell systems, it is also necessary to consider the loss of auxiliary machines such as the battery controller in the fuel cell system and the utilization rate of fuel. Therefore, the efficiency expression of the fuel cell system can be corrected as follows:

[0068]

[0069] Among them, η PCS represents the efficiency of the fuel cell system, P FC Represents the electrical energy generated by the fuel cell, P aux Indicates the auxiliary power consumption of the fuel cell system, mainly including: battery controller power consumption, DC / DC converter power consumption, conditioning circuit power consumption and DSP controller power consumption. η f Indicates the fuel utilization rate of the fuel cell, which is generally between 99% and 100%.

[0070] Since the terminal voltage V SFC It cannot be directly measured, and the loss of the DC / DC converter cannot be directly measured either, so the above formula is modified as follows:

[0071]

[0072] To represent the terminal voltage of a single battery cell. FC_auxIndicates the loss of the battery controller of the fuel cell, mainly including the power consumption of the cooling fan, the loss of the air inlet valve and the air outlet valve, and the loss of the controller circuit.

[0073] In this embodiment, the efficiency is calculated by collecting data on the experimental platform to obtain the relationship curve between the efficiency and current of the fuel cell system, such as Figure 2 As shown, Figure 2 The curve is fitted using the Matlab toolkit, and the high-order polynomial of fuel cell system efficiency-current is obtained as follows:

[0074]

[0075] The determination coefficient of the polynomial is 0.9956, where the determination coefficient represents the effect of polynomial fitting. The closer the determination coefficient is to 1, the better the fitting effect is. The effect of fitting the efficiency-current curve of the fuel cell system using the above formula is as follows: Figure 3 As shown, it can be seen that the fitting effect of the two curves is relatively good, wherein the efficiency-current of the fuel cell system in the full text refers to the output current of the fuel cell.

[0076] However, as the fuel cell system operates, the efficiency-current curve of the fuel cell system will change. In order to fit the efficiency-current curve of the fuel cell system at any operating time, the following formula (5) is used to represent the efficiency-current curve of the fuel cell system:

[0077] η FCS =a6I FC 6 +a5I FC 5 +a4I FC 4 +a3I FC 3 +a2I FC 2 +a i I FC +a0 (5)

[0078] Among them, a0, a1, a2, a3, a4, a5, and a6 represent the coefficients of the efficiency-current function expression of the fuel cell system at any time, that is, the parameters to be identified.

[0079] Step S200 , obtaining values ​​of a plurality of parameters to be identified according to data sets of a fuel cell system at a plurality of moments, so as to obtain a current relationship function.

[0080] Since the efficiency of a fuel cell is closely related to the current output by the fuel cell, the functional relationship between the efficiency and current of the fuel cell system can be identified online based on the data sets of the fuel cell system at multiple times. During the operation of the fuel cell, these parameters will change with the changes in the operating conditions, so it is necessary to use an online identification algorithm to update these parameters in real time to obtain the current relationship function.

[0081] Step S300, obtaining the maximum operating efficiency of the current fuel cell system according to the current relationship function, so that the fuel cell system operates at the maximum operating efficiency.

[0082] As described above, after obtaining the current relationship function, the maximum operating efficiency of the current fuel cell system is obtained by using a high-order equation to find the maximum value. Finally, the battery controller, which can be a DSP controller, controls the fuel cell system to operate at the maximum operating efficiency, wherein the battery controller can control the fuel cell power corresponding to the current maximum operating efficiency point of the fuel cell, and can also control the fuel cell voltage corresponding to the current maximum operating efficiency point of the fuel cell, and can also control the fuel cell voltage corresponding to the current maximum operating efficiency point of the fuel cell to control the fuel cell system to operate at the maximum operating efficiency.

[0083] In one embodiment, if Figure 4 As shown, a flow chart of a method for operating a fuel cell system is provided, wherein step S200 includes step S210.

[0084] Step S210 , calculating the data sets of the fuel cell system at multiple times by using a recursive least squares parameter estimation algorithm to obtain values ​​of multiple parameters to be identified.

[0085] Recursive least squares estimation (RLS) can complete the identification of the parameters to be identified in the fuel cell system, and can also update and correct the system parameters online. Therefore, the RLS algorithm solves the problem of time-varying system parameters changing over time, and can more accurately identify the real-time parameters of the fuel cell system.

[0086] In one embodiment, if Figure 5 As shown, a flow chart of a method for operating a fuel cell system is provided, wherein step S210 includes step S211 and step S212.

[0087] Step S211, constructing the first recursive formula of the recursive least squares parameter estimation algorithm of the fuel cell system, the first recursive formula is used to characterize the recursive relationship between the value of the parameter to be identified at the kth moment and the value of the parameter to be identified at the k-1th moment, the output current of the fuel cell at multiple moments before the kth moment, and the maximum operating efficiency of the fuel cell system at multiple moments before the kth moment.

[0088] From the above description, we can know that the identified fuel cell system operating efficiency-current curve is a single-input single-output (SISO) system, in which the input is the output current of the fuel cell and the output is the maximum operating efficiency of the current fuel cell system, and the autoregressive moving average integral model (ARMA) can be used to describe such a system. The details are as follows:

[0089] A(z -1 )y(k)=B(z -1 )u(kd) (6)

[0090] Among them, y(k) represents the system output, u(k) represents the system input, d represents the system delay, and k represents the discrete time of the system. In addition, for A(z -1 ) and B(z -1 ), and the following formula holds:

[0091]

[0092] In the above formula (7), A(z -1 ) has an order of n a , B(z -1 ) has an order of n b .

[0093] Since the RLS algorithm uses data for recursive calculation, it is necessary to convert formula (6) into the least squares form, as follows:

[0094]

[0095] in, Is a data vector, consisting of output and input data, which is defined as follows:

[0096]

[0097] also, It is the vector of parameters to be solved for the system, which is defined as follows:

[0098]

[0099] For the parameter vector The solution of can be transformed into solving the sum of squares of system errors to minimize it. As shown in the following formula (11):

[0100]

[0101] Where J is the sum of squared errors of the system, and v(k) represents the error between the actual output value and the estimated output value of the system, which is defined by the following formula (12):

[0102]

[0103] in, is an estimated value, which represents the output obtained by the identification algorithm at time k, and can be calculated by the following formula (13):

[0104]

[0105] In formula (13), Indicates the parameters to be identified in the system at the previous moment.

[0106] In addition, in order to facilitate the conversion to recursive form, the following two matrices are defined:

[0107]

[0108] After the derivation and transformation of the above formula, the least squares estimation expression of the system at time k can be obtained, as shown in the following formula (15):

[0109]

[0110] The above formula needs to be further transformed into a recursive form, for which the covariance matrix P is introduced k , used to represent the deviation, P k The definition of is shown in the following formula (16):

[0111]

[0112] Continue the recursion and get the following formula (17):

[0113]

[0114] According to formula (16), the matrix inversion lemma is used to obtain the following formula:

[0115]

[0116] From formula (15) and formula (17), we can know that:

[0117]

[0118] From formula (17) and formula (19), we can know that:

[0119]

[0120] According to equations (15), (16), (17), (19), and (20), the least squares estimate of the system at time k can be re-derived as shown below:

[0121]

[0122] In the above formula, K(k) represents the Kalman gain, and the definition of K(k) is as follows:

[0123]

[0124] Formula (21) links the parameters to be identified at time k and time k-1. According to this formula, the error between the actual value and the estimated value of the system can be used to correct the parameters to be identified at the next time. This can be deduced recursively.

[0125] Substituting formula (18) into formula (22), we can obtain the following formula:

[0126]

[0127] Formula (23) can be obtained:

[0128]

[0129] Where I represents the identity matrix.

[0130] Combining formulas (21), (23), and (24), we finally get the recursive formula of the RLS algorithm, which is as follows:

[0131]

[0132] Step S212, performing calculations based on the first recursive formula and the data sets of the fuel cell system at multiple moments to obtain values ​​of multiple parameters to be identified.

[0133] As mentioned above, according to the above formula (25), that is, the first recursive formula and the collection of input and output data at multiple times, the values ​​of multiple parameters to be identified can be obtained.

[0134] In one embodiment, if Figure 6 As shown, a flow chart of a method for operating a fuel cell system is provided, wherein step S212 includes step S2121 and step S2122.

[0135] Step S2121, generating a second recursive formula according to the forgetting factor and the first recursive formula.

[0136] Since the parameters of the fuel cell system will change with the change of operating conditions, in actual situations, the parameters of the fuel cell system will continue to change, and the input and output data will also continue to change. This will cause the data to continue to increase during the identification process, and there may be a phenomenon of "data saturation". In order to avoid this phenomenon and enhance the impact of new data on identification, the forgetting factor μ is introduced into the above RLS algorithm, and 0<μ<1, forming the FFRLS algorithm. This algorithm has fast identification speed and high accuracy, and has been widely used in engineering practice at present.

[0137] After the forgetting factor is introduced, the error square sum J in the previous formula (11) is modified to the following formula:

[0138]

[0139] Substituting formula (26) into formula (25), we can get the recursive formula of the FFRLS algorithm. Through this recursive formula, we can identify the system parameters at any time, that is, we can get the high-order function expression of the efficiency of the fuel cell system with respect to the current at any time.

[0140]

[0141] Step S2122, performing calculations based on the second recursive formula and the data sets of the fuel cell system at multiple moments to obtain values ​​of multiple parameters to be identified.

[0142] Similarly, this embodiment introduces a forgetting factor based on the above RLS algorithm to obtain the second recursive formula, and based on the collection of input and output data at multiple times, it can obtain the values ​​of multiple parameters to be identified, and can also avoid the phenomenon of "data saturation", while strengthening the role of new data and weakening the role of old data. The use of the FFRLS algorithm can identify system parameters in real time with high accuracy.

[0143] In one embodiment, if Figure 7 As shown, a flow chart of a method for operating a fuel cell system is provided, wherein step S300 includes step S310 and step S320.

[0144] Step S310, obtaining the maximum operating efficiency of the current fuel cell, obtaining a reference current value output by the fuel cell corresponding to the maximum operating efficiency, and obtaining a control signal according to the reference current value.

[0145] Among them, the methods for controlling the output of the fuel cell system are mainly divided into two modes: voltage control and current control. During the operation of the fuel cell system, the output power of the fuel cell always corresponds to the output current or voltage, so the above two methods are essentially the same, but they each have their own advantages and disadvantages. For the voltage control mode, this method directly controls the output voltage of the fuel cell. The sampling speed is fast and the accuracy is relatively high. It is relatively easy to implement on the hardware system, but its disadvantage is that it cannot effectively control the output current. For the current control mode, the advantage of this method is that it can control the operating state of the fuel cell relatively smoothly, and the use of the current control mode is suitable for the control and optimization algorithms of most fuel cell systems during simulation, and the control performance is also significantly better than the voltage control mode.

[0146] In addition, the relationship function obtained in the present invention is a relationship function between the fuel cell system and the output current of the fuel cell, and as discussed above, the relationship function in this embodiment is a high-order equation, and while obtaining the maximum operating efficiency through the high-order function maximum value method, the output current of the fuel cell corresponding to the maximum operating efficiency point can also be obtained at the same time. Therefore, this embodiment can effectively control the fuel cell system to operate at maximum operating efficiency by controlling the output current of the fuel cell and using the output current as the reference current.

[0147] Step S320 , controlling the output current of the fuel cell to be equal to the reference current value according to the control signal, so that the fuel cell system operates at a maximum operating efficiency.

[0148] Specifically, the DSP controller can be used to control the output current of the fuel cell to be equal to the reference current value.

[0149] In one embodiment, if Figure 8 As shown, a schematic flow chart of an operation method of a fuel cell system is provided, and the method further includes steps S400 to S600.

[0150] Step S400: construct a simulation model of a fuel cell system, wherein the simulation model is configured with a relational function.

[0151] Specifically, Fig. 9 The topology of the fuel cell system provided in this embodiment adopts a topology structure in which a fuel cell is cascaded with a DC / DC converter and a lithium-ion battery is added to maintain the bus voltage. Fig. 9In the embodiment, the fuel cell is directly cascaded with the DC / DC converter, so that the output current of the fuel cell can be controlled. In addition, in order to maintain the voltage on the bus, the lithium battery is directly connected to the output bus of the DC / DC converter connected to the bus. In this embodiment, since the simulation model is configured with a relationship function, after obtaining the maximum operating efficiency of the current fuel cell system, specifically, the current output by the DC / DC converter can be controlled by a linear control algorithm, and the output current of the fuel cell in the fuel cell system can be simulated by controlling the fuel cell controller, so that the fuel cell system can operate at maximum efficiency.

[0152] Specifically, since the control system of the actual fuel cell system is relatively complex, in the process of constructing the simulation model, this embodiment only analyzes the key parameters and appropriately simplifies the model. Among them, in the fuel cell system, the load under the actual working condition is usually a DC load, which changes continuously over time. In order to highlight the control effect of the fuel cell system, the DC load is simplified by a controlled current load during the modeling process, and the difficulty of the simulation model is greatly reduced under the condition of ensuring compliance with the actual working condition. In addition, in the control part of the fuel cell system, in order to match the load as a controlled current load and simplify the difficulty of establishing the control model, the control is achieved by comparing the actual output current of the fuel cell with the reference current. For the convenience of control, in the process of identifying parameters, the function expression of the fuel cell efficiency-current curve is identified. In the process of control, the output current of the fuel cell is also controlled to be equal to the reference current, wherein the reference current in this embodiment is the maximum operating efficiency point of the fuel cell system obtained by the fuel cell efficiency-current relationship function during the operation of the fuel cell system, and the corresponding output current of the fuel cell. In addition, in the fuel cell system, the lithium-ion battery is only used to maintain the bus voltage. When the bus voltage is high, the lithium-ion battery is charged, and when the bus voltage is low, the lithium-ion battery is discharged. Therefore, the fuel cell system does not involve the control of lithium-ion batteries, and lithium batteries do not participate in the energy management of the system. When building the simulation model, lithium batteries are not simulated. In addition, in the actual fuel cell system, the converter, fuel cell controller, signal conditioning circuit, etc. all have power losses. In this embodiment, in order to simplify the model during modeling and simulation, this part of the loss is also ignored.

[0153] Specifically, after the above simplification, this embodiment begins to model each part one by one. Therefore, this embodiment also includes the modeling of the topological structure of the above fuel cell system, which can be specifically divided into: fuel cell modeling, DC / DC converter modeling and DC load modeling. The details are as follows:

[0154] Model the fuel cell. The fuel cell is the power source of this system. In the actual operation of the system, its output has a strong nonlinearity, so its model is very complex. It is necessary to analyze many auxiliary equipment of the fuel cell, such as: water pump, radiator, compressor, etc. In this embodiment, the fuel cell model in Matlab / Simulink is used for construction. The model and parameters are as follows Fig.10 As shown, the "m" end of the fuel cell model is the voltage signal and current signal output by the fuel cell model, and an oscilloscope can be connected externally to observe the voltage and current at the output end of the fuel cell. The "+" and "-" ends of the fuel cell model are the output ends of the fuel cell, and the cascade connection with the DC / DC converter is achieved through the "+" and "-" ends.

[0155] Model the DC / DC converter. In the fuel cell system, the DC / DC converter plays an important role because it can convert the output voltage of the fuel cell and control the fuel cell. In addition, since the DC / DC converter can convert direct current into direct current of another characteristic, the output voltage of the fuel cell can be controlled by externally setting the PWM wave applied to the DC / DC converter. The duty cycle of the switching device is controlled to control the average value of the output voltage. Then, filtering is performed at the output to obtain the expected output current.

[0156] Among them, because the fuel cell output is usually unidirectional, and the output current or voltage of the fuel cell is easily affected and changed, its output range is also very large. In many cases, the output voltage of the fuel cell will be lower than the voltage on the DC bus, so it is more appropriate to use a Boost converter and a fuel cell cascade in the fuel cell system, such as Fig.11 shown.

[0157] Fig.11 In the figure, the left side is the input end of the DC / DC converter, and the right side is the output end of the DC / DC converter. The "+FC" and "-FC" on the left are used to connect the two output ends of the "+" and "-" ends of the fuel cell, respectively. Specifically, "+FC" connects the "+" output end of the fuel cell, and "-FC" connects the "-" output end of the fuel cell, thereby realizing the cascade connection of the fuel cell and the DC / DC converter. Fig.11In the figure, Duty is the PWM wave signal applied by the controller to the DC / DC converter, which is used to control the output current of the fuel cell. The "A" end of the DC / DC converter is connected to a first current limiting unit composed of a first inductor and a first resistor in series, the "+" end of the DC / DC converter is connected to the "+" end of the first current measuring unit, and the "+" port of the DC / DC converter is also connected to a first voltage stabilizing unit composed of a second resistor and a first polarity capacitor in series, wherein the "+" end of the DC / DC converter is connected to the positive pole of the polarity capacitor; the "-" end of the DC / DC converter is connected to the negative pole of the polarity capacitor. The "-" end of the above-mentioned first current measuring unit is used to cascade with a DC load, and the "i" end is used to output the current signal of the DC / DC converter. Among them, IFC_DC in the figure represents the current signal output by the DC / DC converter. Fig.11 In the figure, the "+" and "-" terminals on the right are used to cascade with the DC load to form a fuel cell system.

[0158] Model the DC load. The DC load in this embodiment is a controlled current load, and its power is adjustable. The simulation model used in modeling can be found in Fig.12 In the figure, the DC load includes a second current limiting unit connected in series by a second inductor and a third resistor, a second voltage stabilizing unit connected by a fourth resistor and a second polarity capacitor, a controlled current source, a second current measuring unit, a voltage measuring unit, a delay detection unit, and a divider.

[0159] Among them, the "+" end of the second current limiting unit is connected to the "-" end of the first current measuring unit, and the output end of the second current limiting unit is connected to the "-" end of the controlled current source; the "-" end of the controlled current source is connected to the "+" end of the second current measuring unit, the "S" end of the controlled current source is connected to the output end of the divider, the "-" end of the second current measuring unit is connected to the "-" end of the control module, and the "-" end of the second current measuring unit is used to connect an oscilloscope; the input end of the second voltage stabilizing unit is connected to the output end of the second current limiting unit, and the output end of the second voltage stabilizing unit is connected to the positive pole of the controlled current source; the first voltage measuring unit The "+" end of the first current measuring unit is connected to the "-" end of the first voltage measuring unit, the "-" end of the first voltage measuring unit is connected to the "-" end of the DC / DC converter, the "v" of the first voltage measuring unit is connected to the input end of the delay detection unit, and the first voltage measuring unit is used to measure the voltage output by the control module and generate a voltage signal; the "×" end of the divider is used to connect the load, the "÷" end of the divider is connected to the output end of the delay detection unit, and the divider is used to obtain the current control signal according to the input load power and voltage signal; wherein the delay detection unit is used to detect the voltage signal and delay the output of the voltage signal to the divider.

[0160] It can be seen that the DC load is a controlled current source, Pload is the power of the DC load, divided by the voltage on the bus to get the current of the controlled current source in the figure, and from the "S" end in the controlled current source model. Among them, Pload is the constantly changing load condition, Fig.12 In the figure, the "+" and "-" ends on the left are connected to the "+" and "-" ends of the DC / DC converter output, specifically, thereby forming a complete fuel cell system.

[0161] In addition, the simulation model in this embodiment is also configured with the above-mentioned FFRLS algorithm, and after the FFRLS identification algorithm and the maximum operating efficiency calculation, the maximum operating efficiency and the PWM signal for controlling the DC / DC converter are output.

[0162] In summary, in this embodiment, the FFRLS algorithm is connected and packaged with the fuel cell model, DC / DC converter and DC load model, and a fuel cell system model is built on the Matlab / Simulink simulation platform. The fuel cell system model consists of five major parts: fuel cell model, DC / DC converter model, lithium battery model, DC load model, and energy management module. Among them, the energy management method is the FFRLS algorithm in this embodiment. In this fuel cell system model, the DC load power is set according to the actual system. After starting operation, the FFRLS algorithm can identify the parameters to be identified in the operating efficiency-current relationship function expression of the fuel cell system. Then, the maximum efficiency and the current value corresponding to the maximum efficiency are solved by the method of finding the extreme value. Finally, the linear control algorithm is used to change the PWM wave applied to the DC / DC converter to achieve the tracking of the maximum efficiency point of the fuel cell. The overall model of the system is as follows: Fig.13 .

[0163] In the simulation model of this embodiment, the maximum efficiency point tracking is achieved by controlling the fuel cell output reference current. The energy management module uses a linear control algorithm to change the PWM wave applied to the DC / DC converter cascaded with the fuel cell, thereby achieving control of the fuel cell output current.

[0164] Step S500, obtaining a time-efficiency curve generated when the simulation model operates in response to a fluctuating load condition.

[0165] In order to test the effectiveness of the operation method of the fuel cell system in this embodiment, a constantly changing load condition is used for verification. When the load changes, the output current of the fuel cell is observed to determine whether the fuel cell system can still operate at the maximum efficiency point in the operation method of the fuel cell system proposed in this embodiment. The load condition is as follows Fig.14 Based on Fig.14The FFRLS online identification algorithm was tested under load conditions. Substituting the data during system operation into the iterative formula of the FFRLS algorithm, the operating efficiency-current relationship function of the fuel cell can be quickly identified. Then, the reference current value of the fuel cell output corresponding to the maximum operating efficiency is obtained by the extreme value method. Under the control of the linear control algorithm, the output current of the fuel cell is made equal to the reference current value, thereby achieving maximum efficiency tracking. The results are shown in Fig.15 and Fig.16 shown.

[0166] Step S600: analyzing the effectiveness of the relationship function according to the time-efficiency curve.

[0167] Combination Fig.15 and Fig.16 It can be seen that the FFRLS identification algorithm can quickly and accurately achieve maximum efficiency point tracking. Its maximum efficiency is 41.92% and the average is 41.90%. In the process of achieving maximum efficiency tracking, the output current and efficiency change continuously rise until they stabilize at the maximum efficiency point, without obvious fluctuations or even declines, which prolongs the service life of the fuel cell to a certain extent.

[0168] In one embodiment, if Fig.18 As shown, a flow chart of a method for operating a fuel cell system is provided, step S600, including step S610 and step S620.

[0169] Step S610, obtaining a plurality of operating efficiency points and a plurality of average values ​​of operating efficiencies within a first preset time range in a time-efficiency curve.

[0170] Specifically, continue to refer to Fig.16 , obtain multiple operating efficiency points in the time-efficiency curve within the range of 100S to 110S, and obtain the average values ​​of multiple operating efficiencies based on the multiple operating efficiency points.

[0171] Step S620: When the differences between the plurality of operating efficiency points and the average of the operating efficiencies are all smaller than a first preset value, it is determined that the relationship function is valid.

[0172] Specifically, when the differences between the multiple operating efficiency points within the above-mentioned time range of 100s to 110s and the average of the operating efficiency are all less than the first preset value, it means that the data of the time-efficiency curve in this embodiment has converged and the fuel cell system has reached the optimal operating state, that is, the parameters to be identified in the relationship function identified by the FFRLS algorithm in this embodiment are valid.

[0173] In one embodiment, if Fig.19As shown, a flow chart of an operating method of a fuel cell system is provided. In this embodiment, the fuel cell system includes at least a connected fuel cell and an auxiliary machine of the fuel cell system. The auxiliary machine of the fuel cell system is used to receive the output current of the fuel cell and adjust it. The operating method of the fuel cell system in this embodiment includes steps S100, S211, S2121, S2122, S310, S320, S400, S500, S610, and S620.

[0174] Step S100 , constructing a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes a plurality of parameters to be identified.

[0175] Step S211, constructing the first recursive formula of the recursive least squares parameter estimation algorithm of the fuel cell system, the first recursive formula is used to characterize the recursive relationship between the value of the parameter to be identified at the kth moment and the value of the parameter to be identified at the k-1th moment, the output current of the fuel cell at multiple moments before the kth moment, and the maximum operating efficiency of the fuel cell system at multiple moments before the kth moment.

[0176] Step S2121, generating a second recursive formula according to the forgetting factor and the first recursive formula.

[0177] Step S2122, performing calculations based on the second recursive formula and the data sets of the fuel cell system at multiple moments to obtain values ​​of multiple parameters to be identified.

[0178] Step S310, obtaining the maximum operating efficiency of the current fuel cell, obtaining a reference current value output by the fuel cell corresponding to the maximum operating efficiency, and obtaining a control signal according to the reference current value.

[0179] Step S320 , controlling the output current of the fuel cell to be equal to the reference current value according to the control signal, so that the fuel cell system operates at a maximum operating efficiency.

[0180] Step S400: construct a simulation model of a fuel cell system, wherein the simulation model is configured with a relational function.

[0181] Step S500, obtaining a time-efficiency curve generated when the simulation model operates in response to a fluctuating load condition.

[0182] Step S610, obtaining a plurality of operating efficiency points and a plurality of average values ​​of operating efficiencies within a first preset time range in a time-efficiency curve.

[0183] Step S620: When the differences between the plurality of operating efficiency points and the average of the operating efficiencies are all smaller than a first preset value, it is determined that the relationship function is valid.

[0184] Specifically, for the specific limitations in the method steps in this embodiment, please refer to the limitations of the method steps in the above embodiments, which are not limited here.

[0185] This patent proposes a maximum efficiency tracking method for a fuel cell system based on the FFRLS identification algorithm and establishes a fuel cell system simulation model. The topology of the fuel cell system is analyzed and discussed. Combined with the actual working characteristics of the fuel cell, the topology of the fuel cell directly cascaded with the DC / DC converter is determined, which can realize the control of the fuel cell output. Modeling and analysis are carried out on the Matlab / Simulink simulation platform, including fuel cells, DC / DC converters, DC loads, etc.

[0186] Through simulation analysis, it is found that the method proposed in this embodiment can well track the maximum efficiency of the fuel cell system and control the fuel cell to operate at the maximum efficiency point without disturbance.

[0187] The reference current corresponding to the maximum efficiency of the fuel cell output is controlled, and finally the maximum efficiency point tracking of the fuel cell system is achieved.

[0188] The PI control algorithm is then used to control the output current of the fuel cell, which can achieve control of the maximum efficiency of the fuel cell.

[0189] It should be understood that although Figure 1 , Figure 4-Figure 8 , Figure 17-Figure 18 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 , Figure 4-Figure 8 , Figure 17-Figure 18 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0190] In one embodiment, if Fig.19 As shown, a control device 100 for the operation of a fuel cell system is also provided. The device includes a relationship function building module 110 , a parameter identification module 120 and a maximum operation efficiency acquisition module 130 .

[0191] A relationship function construction module 110 constructs a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes multiple parameters to be identified; a parameter identification module 120 identifies the current values ​​of multiple parameters to be identified based on the data sets of the fuel cell system at multiple moments according to the forgetting factor recursive least squares parameter estimation algorithm, and obtains the current relationship function; a maximum operating efficiency acquisition module 130 obtains the maximum operating efficiency of the current fuel cell system according to the current relationship function, and controls the fuel cell system to operate at the maximum operating efficiency; wherein the fuel cell system includes at least a connected fuel cell and a DC / DC converter, and the DC / DC converter is used to receive the output current of the fuel cell and adjust it.

[0192] For the specific limitations of the control device 100 for the operation of the fuel cell system, please refer to the limitations of the fuel cell system operation method above, which will not be repeated here. The various modules in the control device 100 for the operation of the above fuel cell system can be implemented in whole or in part by software, hardware and a combination thereof. The above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0193] A computer device includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the steps of the method for operating the fuel cell system are implemented.

[0194] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for operating the above-mentioned fuel cell system.

[0195] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0196] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0197] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for operating a fuel cell system, characterized in that: The fuel cell system comprises at least a connected fuel cell and an auxiliary machine of the fuel cell system, wherein the auxiliary machine of the fuel cell system is used to receive and adjust the output current of the fuel cell, and the method comprises: Constructing a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes a plurality of parameters to be identified; Acquire values ​​of a plurality of parameters to be identified according to data sets of the fuel cell system at a plurality of moments to acquire the current relationship function; According to the current relationship function, obtaining the maximum operating efficiency of the current fuel cell system, and controlling the fuel cell system to operate at the maximum operating efficiency; The method further comprises: constructing a simulation model of the fuel cell system, wherein the simulation model is configured with the relationship function; Obtaining a time-efficiency curve generated when the simulation model operates in response to a fluctuating load condition; Analyzing the effectiveness of the relationship function according to the time-efficiency curve; Analyzing the effectiveness of the relationship function according to the time-efficiency curve includes: Acquire a plurality of operating efficiency points and a plurality of average values ​​of the operating efficiencies within a first preset time range in the time-efficiency curve; When the differences between the plurality of operating efficiency points and the mean values ​​of the plurality of operating efficiencies are all smaller than a first preset value, it is determined that the relationship function is valid.

2. The method according to claim 1, characterized in that The step of obtaining the values ​​of the plurality of parameters to be identified according to the data sets of the fuel cell system at a plurality of moments includes: The data sets of the fuel cell system at multiple times are calculated by a recursive least squares parameter estimation algorithm to obtain the values ​​of multiple parameters to be identified.

3. The method according to claim 2, characterized in that The calculating of the data sets of the fuel cell system at multiple times by using a recursive least squares parameter estimation algorithm includes: Constructing a first recursive formula of a recursive least squares parameter estimation algorithm for the fuel cell system, wherein the first recursive formula is used to characterize a recursive relationship between a value of the parameter to be identified at the kth moment and a value of the parameter to be identified at the k-1th moment, an output current of the fuel cell at multiple moments before the kth moment, and a maximum operating efficiency of the fuel cell system at multiple moments before the kth moment; Calculation is performed according to the first recursive formula and data sets of the fuel cell system at multiple moments.

4. The method according to claim 3, characterized in that The calculating according to the first recursive formula and the data sets of the fuel cell system at multiple moments includes: Generate a second recursive formula according to the forgetting factor and the first recursive formula; Calculation is performed according to the second recursive formula and data sets of the fuel cell system at multiple moments.

5. The method according to claim 4, characterized in that After obtaining the maximum operating efficiency of the current fuel cell according to the current relationship function, the method further includes: Obtaining a reference current value output by the fuel cell corresponding to the maximum operating efficiency, and obtaining a control signal according to the reference current value; The controlling the fuel cell system to operate at the maximum operating efficiency comprises: The output current of the fuel cell is controlled to be equal to the reference current value according to the control signal, so that the fuel cell system operates at the maximum operating efficiency.

6. A control device for the operation of a fuel cell system, characterized in that: include: A relationship function building module, which builds a relationship function between the operating efficiency of the fuel cell system and the output current of the fuel cell, wherein the relationship function includes a plurality of parameters to be identified; A parameter identification module, which identifies the values ​​of the multiple parameters to be identified according to the data sets of the fuel cell system at multiple moments according to the forgetting factor recursive least squares parameter estimation algorithm, and obtains the current relationship function; A maximum operating efficiency acquisition module, which acquires the maximum operating efficiency of the current fuel cell system according to the current relationship function, and controls the fuel cell system to operate according to the maximum operating efficiency; Wherein, the fuel cell system at least comprises a connected fuel cell and an auxiliary machine of the fuel cell system, wherein the auxiliary machine of the fuel cell system is used to receive the output current of the fuel cell and perform regulation; The control device is also used to construct a simulation model of the fuel cell system, and the simulation model is configured with the relationship function; Obtain a time-efficiency curve generated when the simulation model operates in response to a fluctuating load condition; analyze the effectiveness of the relationship function based on the time-efficiency curve; the control device is also used to obtain a plurality of operating efficiency points and a plurality of average values ​​of the operating efficiencies within a first preset time range in the time-efficiency curve; when the difference between the plurality of operating efficiency points and the plurality of average values ​​of the operating efficiencies is less than a first preset value, determine that the relationship function is valid.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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