A control method and system for a fuel cell engine air supply system

Abstract

The present invention relates to a control method and system for a fuel cell engine air supply system. The method comprises: S1: obtaining an air intake mass flow request value #imgabs0# and a pressure request value p under the current fuel cell operating current; req , and after processing, the air compressor speed feedforward reference value n is obtained ref and the throttle opening feedforward reference value θ ref ; S2: Get the mass flow control error #imgabs1# and the pressure control error e p ; S3: #imgabs2# and e p Input the mass flow PID controller and pressure PID controller respectively; S4: obtain the air compressor speed compensation value n c and throttle angle compensation value θ c ; S5: Get the air compressor speed request value n req and the throttle opening request value θ req , and n req and θ req The air compressor speed control circuit and the throttle opening control circuit are inputted respectively. The present invention reduces the coupling degree of air intake mass flow and pressure, and improves control accuracy and stability.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicle technology, and in particular to the field of vehicle fuel cell engine control. Background Art

[0002] Fuel cell vehicles have attracted widespread attention due to their zero emissions, high efficiency and fast hydrogen refueling speed. The fuel cell engines they are equipped with are usually composed of subsystems such as air supply system, hydrogen supply system, water thermal management system and power control system. In actual operation, the fuel cell engine for vehicles has high real-time control accuracy and control stability requirements for system operating conditions such as stack temperature, air intake flow and pressure. This is because these operating conditions must quickly and accurately follow the dynamic power changes of the fuel cell engine to ensure the performance of the fuel cell engine and avoid irreversible stack life degradation. Therefore, high-precision subsystem control is crucial for automotive fuel cell engines, especially the control of the air supply system, considering that the irreversible degradation of the membrane electrode is closely related to the gas starvation phenomenon caused by insufficient air supply.

[0003] like Figure 1 As shown, the air supply system hardware is mainly composed of air filter, mass flow sensor, air compressor, intercooler, humidifier, air pressure sensor and throttle. The main function of the air supply system is to achieve precise air intake mass flow and pressure control through coordinated adjustment of air compressor speed and throttle opening, so that air is continuously and stably supplied to the cathode inlet of the fuel cell to ensure continuous reaction and power generation of the fuel cell. For fuel cells, the air intake mass flow and pressure have a great influence on their performance and durability, and the influence mechanism is as follows:

[0004] The air intake mass flow determines the fuel cell cathode air metering ratio. The slow and inaccurate air intake mass flow control effect will affect the dynamic response performance of the fuel cell power on the one hand, and on the other hand, it is easy to cause global gas starvation during the fuel cell power load change period, causing the carbon-based support structure of the fuel cell catalyst to participate in the chemical reaction, causing irreversible dissolution of the carbon-based support structure, further causing the catalyst platinum particles to fall off, lose or agglomerate, reducing the electrochemical active surface area of ​​the catalyst layer, and even the collapse of the electrode structure. In addition, the reduction of carbon content caused by global gas starvation will also make the electrode thinner, increase the mass transfer resistance of gas and generated water, and lead to very high concentration loss and ohmic loss.

[0005] The control effect of air intake pressure affects the mass transfer and diffusion process of air in the gas diffusion layer. If the air intake pressure is insufficient or drops suddenly, it will slow down the rate at which the gas diffuses from the flow channel through the gas diffusion layer into certain reaction areas of the catalyst layer, resulting in uneven gas distribution in local areas. During the dynamic loading process of the fuel cell, these areas are often prone to local gas starvation, affecting the durability of the fuel cell. In addition, a stable air intake pressure is also a key factor in ensuring that the reaction interface of the fuel cell catalyst layer has a higher oxygen concentration. High oxygen concentration can accelerate electrochemical reactions, reduce activation losses and concentration losses, and thus obtain better power output performance.

[0006] Therefore, high-precision control of air supply mass flow and pressure is crucial to fuel cell performance and durability. However, the air supply system of a fuel cell engine is a typical two-input and two-output coupled control object. The air intake mass flow and pressure will be affected by either the air compressor speed or the throttle opening. This means that when one of the air intake mass flow and pressure is changed by control, the other variable will be affected. To achieve high-performance air supply system control, it is necessary to reduce the mutual coupling of air intake mass flow and pressure to avoid a sudden drop in pressure when controlling mass flow, or a sudden drop in mass flow when controlling pressure, which will cause a short and rapid shortage of reaction material supply, causing material starvation and affecting the life and durability of the fuel cell.

[0007] The prior art calculates the mass flow error based on the feedback value of the flow sensor, and inputs the error into the model-free adaptive sliding film controller to obtain the air compressor speed control reference value N cmd For pressure control, the mass flow error calculated based on the pressure sensor feedback value is input into another independent backstepping controller to obtain the throttle opening control reference value θ cmd . In this patent, the control loops of mass flow and pressure are independent of each other, that is, the control of mass flow is achieved only by changing the air compressor speed, and the control of pressure is achieved only by changing the throttle opening. The influence of the change of air compressor speed on pressure and the influence of the change of throttle opening on flow are not considered. The problem of cross-coupling relationship between the two input variables (air compressor speed and throttle opening) and the two output variables (mass flow and pressure) in the "dual input-dual output" control system is not solved. This method easily causes the remaining variable to fluctuate greatly when controlling and changing any one of the variables, mass flow and pressure. Summary of the invention

[0008] One of the purposes of the present invention is to provide a control method for a fuel cell engine air supply system to solve the problem that when the prior art controls change any one of the variables, mass flow and pressure, the remaining other variable experiences large fluctuations; the second purpose is to provide a control system for a fuel cell engine air supply system.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A control method for a fuel cell engine air supply system, the method specifically comprising:

[0011] S1: Based on the actual value of the fuel cell output current I act , obtain the air intake mass flow request value under the current fuel cell operating current and pressure request value p req , and after processing, the air compressor speed feedforward reference value n is obtained ref and the throttle opening feedforward reference value θ ref ;

[0012] S2: According to the actual value of mass flow and the actual pressure value p act , get the mass flow control error And the pressure control error e p ;

[0013] S3: Mass flow control error And the pressure control error e p Input the mass flow PID controller and pressure PID controller respectively;

[0014] S4: Input the output values ​​of the mass flow PID controller and the pressure PID controller into the decoupler to obtain the air compressor speed compensation value n c and throttle angle compensation value θ c ;

[0015] S5: Feed forward the air compressor speed reference value n ref Compensation value n for air compressor speed c The sum is the air compressor speed request value n req , the throttle opening feedforward reference value θ ref and throttle angle compensation value θ c The sum is the throttle opening request value θ req , and n req and θ req They are input into the air compressor speed control loop and the throttle opening control loop respectively.

[0016] According to the above technical means, the feedforward control reference value of the air compressor speed and throttle opening is first determined according to the requested value of the air intake mass flow and pressure, and then the PID controller output value obtained according to the mass flow error and pressure error is decoupled by using a dual-input dual-output decoupler to obtain the air compressor speed and throttle opening control compensation value, and the sum of the feedforward control reference value and the control compensation value output by the decoupler is used as the final request signal value of the air compressor speed and throttle opening, thereby realizing the coordinated decoupling control of the air compressor speed and throttle opening under different requested mass flows and pressures. Through the decoupling control of the air compressor speed and throttle opening, the coupling degree of the air compressor speed and throttle opening is reduced, the influence of the control change on the pressure stability after the mass flow is changed or the influence of the control change on the mass flow stability after the pressure is changed is reduced, and the large fluctuation of the pressure or mass flow caused by the large coupling between the two is avoided.

[0017] Furthermore, if the mass flow sensor that obtains the actual value of the mass flow fails, is 0; if the pressure sensor that obtains the actual pressure value fails, then set e p is 0.

[0018] According to the above technical means, the introduced sensor failure determination flag can realize the function of cutting off the decoupler feedback compensation loop after the sensor fails, thereby ensuring system reliability.

[0019] Further, the decoupling method of the decoupler in S4 is based on a discrete transfer function matrix

[0020]

[0021] The discrete transfer function matrix Obtained by the following method:

[0022] The transfer function matrix is ​​obtained according to the following formula:

[0023]

[0024] The transfer function matrix in the form of a continuous transfer function Discretization processing is performed;

[0025] Where: G 11 (S) represents the first-order transfer function of the air intake mass flow rate relative to the compressor speed step signal;

[0026] G 21 (S) represents the first-order transfer function of air intake pressure relative to the compressor speed step signal;

[0027] G 12(S) represents the first-order transfer function of the air intake mass flow rate relative to the throttle opening step signal;

[0028] G 22 (S) represents the first-order transfer function of the air intake pressure relative to the throttle opening step signal.

[0029] Further, obtain the air compressor speed feedforward reference value n ref The method is:

[0030] Conducting an experimental test, obtaining steady-state values ​​of air intake mass flow rate and pressure under different air compressor speeds as effective values, and obtaining a first test data matrix, wherein the first test data matrix includes 3 columns of data, respectively representing the air compressor speed, the air intake mass flow rate, and the air intake pressure;

[0031] The three columns of data in the first test data matrix are used as input data for the X-axis, Y-axis, and Z-axis, and surface interpolation and fitting are performed to obtain the air compressor speed feedforward reference value n ref About m req and p req 2D feedforward data table based on the compressor speed feedforward reference value n ref About m req and p req 2D feedforward data table to obtain the compressor speed feedforward reference value n ref .

[0032] Furthermore, the throttle opening feedforward reference value θ ref The method to obtain is:

[0033] The experimental test is carried out, and the steady-state values ​​of the air intake mass flow rate and pressure under different throttle openings are selected as effective values ​​to obtain a second test data matrix, which includes 3 columns of data, namely, throttle opening, air intake mass flow rate and air intake pressure. The three columns of data of the second test data matrix are respectively the input data of the X-axis, Y-axis and Z-axis, and the surface interpolation and fitting are performed to obtain the throttle opening feedforward reference value θ ref about and p req The 2D feedforward data table is based on the throttle opening feedforward reference value θ ref about and p req 2D feedforward data table, and obtain the throttle opening feedforward reference value θ ref .

[0034] Further, the method for determining whether the sensor is invalid is:

[0035] Step ①: Set the sensor failure flag SensorFaultFlag and the controller I / O port power supply fault flag MCUPwrErrFlg to 0;

[0036] Step ②: Obtain the sensor signal in real time and determine whether it is within the sensor signal range. If it is within the range, jump to step ③; if it is not within the range, jump to step ④;

[0037] Step ③: Set SensorFaultFlag = 0, enter the next sampling time point, and return to step ②;

[0038] Step ④: Determine whether the controller I / O port pin power supply voltage MCUPinVltg is greater than the voltage threshold VltgThreshold, if so, jump to step ⑤, if less, jump to step ⑥;

[0039] Step ⑤: Set SensorFaultFlag = 1, enter the next sampling time point, and return to step ②;

[0040] Step ⑥: Set MCUPwrErrFlg = 1, enter the next sampling time point, and return to step ②;

[0041] If SensorFaultFlg=0, the sensor is not failed, and if SensorFaultFlg=1, the sensor is failed, and the sensor is a mass flow sensor or a pressure sensor.

[0042] Furthermore, the method further comprises the following steps:

[0043] S6: according to the throttle opening request value θ req And the actual value of air compressor speed n act ; Get the air compressor speed control error e n , according to the air compressor speed request value n req and the actual throttle opening value θ act , get the throttle opening control error e θ ;

[0044] S7, the air compressor speed control error e n and throttle opening control error e θ The signals are input to the air compressor speed controller and the throttle valve opening controller respectively, and the execution action signals of the air compressor and the throttle valve are output.

[0045] According to the above technical means, closed-loop control of the air compressor speed and throttle opening is achieved.

[0046] Further, the equation of the mass flow PID controller is:

[0047]

[0048] Where: k p1 is the proportional control coefficient of the mass flow PID controller, k i1 is the integral control coefficient of the mass flow PID controller, k d1 is the differential control coefficient of the mass flow PID controller, e1(t) is the mass flow control error at the current moment, and u1(t) is the output value of the mass flow PID controller.

[0049] Further, the equation of the pressure PID controller is:

[0050]

[0051] Where: k p2 is the proportional control coefficient of the pressure PID controller, k i2 is the integral control coefficient of the pressure PID controller, k d2 is the differential control coefficient of the pressure PID controller, e2(t) is the pressure control error at the current moment, and u2(t) is the output value of the pressure PID controller.

[0052] A control system for a fuel cell engine air supply system based on the above control method is characterized by comprising:

[0053] The feedforward reference value acquisition module is configured to be based on the actual value of the fuel cell output current I act , obtain the air intake mass flow request value under the current fuel cell operating current and pressure request value p req , and after processing, the air compressor speed feedforward reference value n is obtained ref and the throttle opening feedforward reference value θ ref ;

[0054] Difference acquisition module, configured to receive the actual value of mass flow and actual pressure value

[0055] p act , and obtain the mass flow control error And the pressure control error e p , and the mass flow control error And the pressure control error e p Input into the mass flow PID controller and pressure PID controller respectively;

[0056] The decoupler is configured to receive the output results of the mass flow PID controller and the pressure PID controller to obtain the air compressor speed compensation value n c and throttle angle compensation value θc ;

[0057] The request value acquisition module is configured to feed forward the air compressor speed reference value n ref Compensation value n for air compressor speed c The sum is the air compressor speed request value n req , the throttle opening feedforward reference value θ ref and throttle angle compensation value θ c The sum is the throttle opening request value θ req , and n req and θ req They are input into the air compressor speed control loop and the throttle opening control loop respectively.

[0058] Furthermore, it also includes a sensor judgment module, which is configured to judge whether the mass flow sensor and the pressure sensor are invalid. If the mass flow sensor that obtains the actual value of the mass flow fails, then set e m is 0 and is input into the mass flow PID controller; if the pressure sensor that obtains the actual pressure value fails, then let e p is 0 and is input into the pressure PID controller.

[0059] Furthermore, the sensor judgment module uses the following judgment method:

[0060] Step ①: Set the sensor failure flag SensorFaultFlag and the controller I / O port power supply fault flag MCUPwrErrFlg to 0;

[0061] Step ②: Obtain the sensor signal in real time and determine whether it is within the sensor signal range. If it is within the range, jump to step ③; if it is not within the range, jump to step ④;

[0062] Step ③: Set SensorFaultFlag = 0, enter the next sampling time point, and return to step ②;

[0063] Step ④: Determine whether the controller I / O port pin power supply voltage MCUPinVltg is greater than the voltage threshold VltgThreshold, if so, jump to step ⑤, if less, jump to step ⑥;

[0064] Step ⑤: Set SensorFaultFlag = 1, enter the next sampling time point, and return to step ②;

[0065] Step ⑥: Set MCUPwrErrFlg = 1, enter the next sampling time point, and return to step ②;

[0066] If SensorFaultFlg=0, the sensor is not failed, and if SensorFaultFlg=1, the sensor is failed, and the sensor is a mass flow sensor or a pressure sensor.

[0067] Furthermore, the decoupling method of the decoupler is based on a discrete transfer function matrix

[0068]

[0069] The discrete transfer function matrix Obtained by the following method:

[0070] The transfer function matrix is ​​obtained according to the following formula:

[0071]

[0072] The transfer function matrix in the form of a continuous transfer function Discretization processing is performed;

[0073] Where: G 11 (S) represents the first-order transfer function of the air intake mass flow rate relative to the compressor speed step signal;

[0074] G 21 (S) represents the first-order transfer function of air intake pressure relative to the compressor speed step signal; G 12 (S) represents the first-order transfer function of the air intake mass flow rate relative to the throttle opening step signal;

[0075] G 22 (S) represents the first-order transfer function of the air intake pressure relative to the throttle opening step signal.

[0076] Beneficial effects of the present invention:

[0077] The present invention reduces the coupling degree between air intake mass flow and pressure, reduces the influence of controlling the mass flow rate to pressure stability or the influence of controlling the pressure to mass flow stability, and improves control accuracy and control stability.

[0078] The present invention has a higher control fault tolerance capability. When the sensor fails and cannot feedback the correct value, the air compressor and the throttle valve can be operated in an emergency manner only by relying on the feedforward reference value, thereby avoiding the sudden starvation of the reactant in the fuel cell caused by the sudden interruption of the gas supply.

[0079] The use of the decoupler of the present invention allows the regulation of either the air intake mass flow rate or the pressure to be completed by the cooperation of the air compressor and the throttle, rather than only performing pressure compensation control through a single throttle component, and performing mass flow compensation control through a single air compressor component. This can reduce the fluctuation degree of the throttle opening and the air compressor speed feedback compensation value. For the air compressor, it can reduce the speed fluctuation, which is beneficial to extending the service life under long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 It is the basic component of the fuel cell engine system;

[0081] Figure 2 Principle of air supply control system;

[0082] Figure 3 This is a schematic diagram of the control method described in Example 1;

[0083] Figure 4 It is the sensor failure verification method process;

[0084] Figure 5 is a structural diagram of the control system described in Example 2;

[0085] Figure 6 The mass flow stabilization process and effect of the method of the present invention and the method of the prior art under varying pressure in Example 3;

[0086] Figure 7 The pressure stabilization process and effect of the method of the present invention and the method of the prior art under varying mass flow rates in Example 3 are shown.

[0087] Among them, 1-feedforward reference value acquisition module; 2-difference acquisition module; 3-decoupler; 4-request value acquisition module; 5-sensor judgment module. DETAILED DESCRIPTION

[0088] The following will refer to the accompanying drawings and preferred embodiments to illustrate the implementation of the technical solution of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0089] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0090] Example 1

[0091] The fuel cell engine air supply system of the present invention is basically composed of the following hardware: Figure 1 As shown in the figure, it mainly includes air filter, mass flow sensor, air compressor, intercooler, humidifier, air pressure sensor and throttle. The control principle of the air supply system is as follows Figure 2 As shown,

[0092] This embodiment provides a control method for a fuel cell engine air supply system. Figure 2 and Figure 3 As shown, the control method is specifically as follows:

[0093] S1: According to the actual value of the fuel cell output current I collected by the current sensor act , through two one-dimensional data tables of air intake mass flow rate and pressure request value at different current values, determine the air intake mass flow rate request value under the current fuel cell operating current and pressure request value p req , two one-dimensional data tables are prior art.

[0094] The air intake mass flow request value after the change rate limiter and pressure request value p req Input to the air compressor speed feedforward reference value n ref about and p req 2D feedforward data table and throttle opening feedforward reference value θ ref about and p req In the 2D feedforward data table, we get the corresponding and p req The air compressor speed feedforward reference value n under ref and the throttle opening feedforward reference value θ ref .

[0095] In this embodiment, the air compressor speed feedforward reference value n ref about and p req 2D feedforward data table and throttle opening feedforward reference value θ ref about and p reqThe method of obtaining the 2D feedforward data table is based on the following experiment: Figure 1 Build an experimental system according to the basic component schematic diagram of the fuel cell engine system shown in the figure, start the high-voltage power supply and low-voltage power supply of the fuel cell engine test system, ensure that the air compressor and throttle can respond to the speed request value and the opening request value, set the air compressor speed to the initial value, such as 20000rpm, keep the air compressor speed unchanged, and increase the throttle opening from the initial value, such as 16°, to 90° in steps of 2°. The test time at each opening is 20 seconds, and the time series test data of the air compressor speed, throttle opening, air intake mass flow rate and pressure are recorded with a sampling time of 100 milliseconds. Adjust the throttle opening from 90° back to the initial value, increase the air compressor speed by 1000rpm, if the increased air compressor speed exceeds the upper limit speed.

[0096] Based on the above test, the air compressor speed feedforward reference value n ref about and p req The method for obtaining the 2D feedforward data table is as follows: obtaining the steady-state values ​​of the air intake mass flow rate and pressure under different air compressor speeds as effective values, and obtaining a first test data matrix, wherein the first test data matrix includes 3 columns of data, respectively representing the air compressor speed, the air intake mass flow rate and the air intake pressure;

[0097] The three columns of data in the first test data matrix are used as input data for the X-axis, Y-axis, and Z-axis, and surface interpolation and fitting are performed to obtain the air compressor speed feedforward reference value n ref about and p req 2D feedforward data table based on the compressor speed feedforward reference value n ref about and p req 2D feedforward data table to obtain the compressor speed feedforward reference value n ref .

[0098] Based on the above test, the throttle opening feedforward reference value θ ref about and p req The 2-dimensional feedforward data table is obtained as follows:

[0099] The steady-state values ​​of the air intake mass flow rate and pressure under different throttle openings are selected as effective values ​​to obtain a second test data matrix, which includes three columns of data, namely, throttle opening, air intake mass flow rate and air intake pressure. The three columns of data of the second test data matrix are respectively the input data of the X-axis, Y-axis and Z-axis, and surface interpolation and fitting are performed to obtain the throttle opening feedforward reference value θ ref about and preq The 2D feedforward data table is based on the throttle opening feedforward reference value θ ref about and p req 2D feedforward data table, and obtain the throttle opening feedforward reference value θ ref .

[0100] S2: Actual value of mass flow rate according to feedback from mass flow sensor and the actual pressure value p fed back by the pressure sensor act , by calculating the pressure request value p req The actual pressure value p fed back by the pressure sensor act The pressure control error e is calculated by the difference between p ; By calculating the air intake mass flow request value The actual value of mass flow rate fed back by the mass flow sensor The difference between the mass flow control error

[0101] S3: Mass flow control error And the pressure control error e p Enter the mass flow PID controller and the pressure PID controller respectively.

[0102] Before input, determine whether the mass flow sensor and pressure sensor are invalid. If the mass flow sensor that obtains the actual value of mass flow fails, is 0; if the pressure sensor that obtains the actual pressure value fails, then set e p is 0.

[0103] If it does not fail, and e p The actual value of is input into the mass flow PID controller and the pressure PID controller.

[0104] In this embodiment, the scheme for determining whether the sensor is invalid is as follows, that is, the following means are used to determine whether the mass flow sensor and the pressure sensor are invalid. Figure 4 shown.

[0105] Step ①: Set the sensor failure flag SensorFaultFlag and the controller I / O port power supply fault flag MCUPwrErrFlg to 0;

[0106] Step ②: Obtain the sensor signal in real time and determine whether it is within the sensor signal range. If it is within the range, jump to step ③; if it is not within the range, jump to step ④;

[0107] Step ③: Set SensorFaultFlag = 0, enter the next sampling time point, and return to step ②;

[0108] Step ④: Determine whether the controller I / O port pin power supply voltage MCUPinVltg is greater than the voltage threshold VltgThreshold, if so, jump to step ⑤, if less, jump to step ⑥;

[0109] Step ⑤: Set SensorFaultFlag = 1, enter the next sampling time point, and return to step ②; Step ⑥: Set MCUPwrErrFlg = 1, enter the next sampling time point, and return to step ②;

[0110] If SensorFaultFlg=0, the sensor is not failed, and if SensorFaultFlg=1, the sensor is failed.

[0111] In this embodiment, the equation of the mass flow PID controller is:

[0112]

[0113] Where: k p1 is the proportional control coefficient of the mass flow PID controller, k i1 is the integral control coefficient of the mass flow PID controller, k d1 is the differential control coefficient of the mass flow PID controller, e1(t) is the mass flow control error at the current moment, and u1(t) is the output value of the mass flow PID controller.

[0114] The equation for the pressure PID controller is:

[0115]

[0116] Where: k p2 is the proportional control coefficient of the pressure PID controller, k i2 is the integral control coefficient of the pressure PID controller, k d2 is the differential control coefficient of the pressure PID controller, e2(t) is the pressure control error at the current moment, and u2(t) is the output value of the pressure PID controller.

[0117] The mass flow control error And the pressure control error e p Input the mass flow PID controller and pressure PID controller respectively to obtain u1(t) and u2(t).

[0118] In this embodiment, INCA software is used to complete the proportional control coefficient k of the PID controller. p , integral control coefficient ki and the differential control coefficient k d Online calibration. Or calibrate the proportional control coefficient k through experiments p , integral control coefficient k i and the differential control coefficient k d The best value.

[0119] S4: The output values ​​of the mass flow PID controller and the pressure PID controller (u1(t) and u2 ( t)) is input into the decoupler to obtain the air compressor speed compensation value n c and throttle angle compensation value θ c .

[0120] The decoupling method of the decoupler in this embodiment is:

[0121] according to Figure 1 The experimental system is built by the basic schematic diagram of the fuel cell engine system shown in the figure;

[0122] Start the high-voltage power supply and low-voltage power supply of the fuel cell engine test system to ensure that the air compressor and throttle valve can respond to the speed request value and the opening request value;

[0123] The throttle opening is set to a fixed value, such as 40°, and the air compressor speed is adjusted from working point 1 to working point 2 in a step-by-step manner using a request signal, such as from 30,000 rpm to 60,000 rpm. The relative changes in the air compressor speed, air intake mass flow rate, and pressure during this process are recorded with a sampling time of 10 milliseconds.

[0124] Set the air compressor speed to a fixed value, such as 60000rpm, and then adjust the throttle opening from working point 1 to working point 2 in a step-by-step manner with a request signal, such as from 30° to 50°, and record the relative change time series data of the throttle opening, air intake mass flow rate and pressure during this process with a sampling time of 10 milliseconds;

[0125] Input the step change time series data of air intake mass flow rate and air compressor speed into the MATLAB system identification tool to identify the first-order transfer function G of air intake mass flow rate relative to the air compressor speed step signal 11 (S);

[0126] The step change time series data of air intake pressure and air compressor speed are input into the MATLAB system identification tool to identify the first-order transfer function G of air intake pressure relative to the air compressor speed step signal. 21 (S);

[0127] The step change time series data of air intake mass flow and throttle opening are input into the MATLAB system identification tool to identify the first-order transfer function G of air intake mass flow relative to the throttle opening step signal. 12 (S);

[0128] The step change time series data of air intake pressure and throttle opening are input into the MATLAB system identification tool to identify the first-order transfer function G of air intake pressure relative to the throttle opening step signal. 22 (S);

[0129] The transfer function G 11 (S), G 21 (S), G 12 (S) and G 22 (S) Substitute into the following equation to solve for the decoupler transfer function matrix:

[0130]

[0131] Get the transfer function matrix of the decoupler

[0132] The decoupler in the form of a continuous transfer function Discretization is performed to obtain the discrete transfer function matrix As a decoupler used in embedded systems.

[0133] The air compressor speed control error e n The throttle opening control error e8 is input to the air compressor speed controller and the throttle opening controller respectively, and the execution action signals of the air compressor and the throttle are output, thereby closed-loop controlling the air compressor speed and the throttle opening.

[0134] The air compressor speed feedforward reference value n ref Compensation value n for air compressor speed c The sum is the air compressor speed request value n req , the throttle opening feedforward reference value θ ref and throttle angle compensation value θ c The sum is the throttle opening request value θ req .

[0135] S6: according to the throttle opening request value θ req And the actual value of air compressor speed n act ; Get the air compressor speed control error e n , according to the air compressor speed request value n req and the actual throttle opening value θ act , get the throttle opening control error e θ ;

[0136] S7, the air compressor speed control error e n The throttle opening control error e8 is input to the air compressor speed controller and the throttle opening controller respectively, and the execution action signals of the air compressor and the throttle are output, thereby realizing the closed-loop control of the air compressor speed and the throttle opening.

[0137] In this embodiment, according to the air compressor speed request value and the throttle opening request value, the actual air compressor speed and throttle opening are controlled to the requested values ​​through the air compressor speed closed-loop control and the throttle opening closed-loop control respectively. This control process will cause the actual flow and pressure to change dynamically. The transfer function model of the air system flow pressure with respect to the air compressor speed and the throttle opening is: Figure 2 and Figure 3 In G11, G12, G21, and G22, the actual flow and pressure values ​​will be fed back to step S2 of this control strategy to compensate for the air compressor speed and throttle opening.

[0138] Example 2

[0139] This embodiment proposes a control system for a fuel cell engine air supply system, based on the method described in embodiment 1, such as Figure 5 As shown, including:

[0140] The feedforward reference value acquisition module 1 is configured to be based on the actual value I of the fuel cell output current act , obtain the air intake mass flow request value under the current fuel cell operating current and pressure request value p req , and after processing, the air compressor speed feedforward reference value n is obtained ref and the throttle opening feedforward reference value θ ref ;

[0141] Difference acquisition module 2, configured to receive the actual value of mass flow and actual pressure value

[0142] p act , and obtain the mass flow control error And the pressure control error e p , and the mass flow control error And the pressure control error e p Input into the mass flow PID controller and pressure PID controller respectively;

[0143] Decoupler 3 is configured to receive the output results of the mass flow PID controller and the pressure PID controller to obtain the air compressor speed compensation value n c and throttle angle compensation value θ c ;

[0144] The request value acquisition module 4 is configured to feed forward the air compressor speed reference value n ref Compensation value n for air compressor speed c The sum is the air compressor speed request value n req , the throttle opening feedforward reference value θ req and throttle angle compensation value θ c The sum is the throttle opening request value θ req , and n req and θ req They are input into the air compressor speed control loop and the throttle opening control loop respectively.

[0145] The sensor judgment module 5 is configured to judge whether the mass flow sensor and the pressure sensor are invalid. If the mass flow sensor that obtains the actual value of the mass flow fails, is 0 and is input into the mass flow PID controller; if the pressure sensor that obtains the actual pressure value fails, then let e p is 0 and is input into the pressure PID controller.

[0146] Example 3

[0147] This embodiment carries out a verification test on the control stability of the intake mass flow rate by changing the intake pressure, and the steps are as follows:

[0148] 1. Disconnect the external circuit connecting the fuel cell engine and the electronic load, supply nitrogen to the anode of the fuel cell engine under test, and maintain the pressure difference between the cathode and cathode to 0.1 bar;

[0149] 2. Set the requested value of air intake mass flow rate to a fixed value of 30 g / s, and set the requested value of air intake pressure to vary between the interval [0.3 bar, 0.7 bar];

[0150] 3. Record the requested and actual values ​​of the air intake mass flow rate and pressure during the test with a sampling time of 100ms.

[0151] Furthermore, a verification test of the stability of intake pressure control by changing the intake mass flow rate is carried out, and the steps are as follows:

[0152] 1. Disconnect the external circuit connecting the fuel cell engine and the electronic load, supply nitrogen to the anode of the fuel cell engine under test, and maintain the pressure difference between the cathode and cathode to 0.1 bar;

[0153] 2. Set the requested value of air intake pressure to a fixed value of 0.5 bar, and set the requested value of air intake mass flow rate to vary between the interval [20 g / s, 50 g / s];

[0154] 3. Record the requested and actual values ​​of the air intake mass flow rate and pressure during the test with a sampling time of 100ms.

[0155] The test results obtained by the method of Example 1 are compared with the test results obtained by a control method without a decoupler and based only on the combination of feedforward and PID feedback.

[0156] Using the control method of the present invention, the following should be achieved: Figure 6 and Figure 7 Compared with the control method without decoupler and only using feedforward and PID feedback, Figure 6 As shown in (c)-(d), the control method of the present invention can achieve a more stable mass flow control effect under a changing intake pressure. As shown in FIG7(a)-(b), the control method of the present invention can achieve a more stable pressure control effect under a changing intake mass flow. Figure 6 (i) and Figure 6 (j) and Figure 7 (i) and Figure 7 (j) The method of the present invention can make the air compressor speed compensation amount change smaller, and finally make Figure 6 (f) and Figure 7 The air compressor speed shown in (f) is more stable, reducing the air compressor speed fluctuation.

[0157] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A control method for a fuel cell engine air supply system, characterized in that: The method is specifically as follows: S1: Based on the actual value of the fuel cell output current I act , obtain the air intake mass flow request value under the current fuel cell operating current and pressure request value p req , and after processing, the air compressor speed feedforward reference value n is obtained ref and the throttle opening feedforward reference value θ ref ; S2: According to the actual value of air intake mass flow and the actual pressure value p act , get the mass flow control error And the pressure control error e p ; S3: Mass flow control error And the pressure control error e p Input the mass flow PID controller and pressure PID controller respectively; S4: Input the output values ​​of the mass flow PID controller and the pressure PID controller into the decoupler to obtain the air compressor speed compensation value n c and throttle angle compensation value θ c ; S5: Feed forward the air compressor speed reference value n ref Compensation value n for air compressor speed c The sum is the air compressor speed request value n req , the throttle opening feedforward reference value θ ref and throttle angle compensation value θ c The sum is the throttle opening request value θ req , and n req and θ req Input into the air compressor speed control loop and the throttle opening control loop respectively; The decoupling method of the decoupler in S4 is based on a discrete transfer function matrix The discrete transfer function matrix Obtained by the following method: The transfer function matrix is ​​obtained according to the following formula: The transfer function matrix in the form of a continuous transfer function Discretization processing is performed; Where: G 11 (S) represents the first-order transfer function of the air intake mass flow rate relative to the compressor speed step signal; G 21 (S) represents the first-order transfer function of air intake pressure relative to the compressor speed step signal; G 12 (S) represents the first-order transfer function of the air intake mass flow rate relative to the throttle opening step signal; G 22 (S) represents the first-order transfer function of the air intake pressure relative to the throttle opening step signal.

2. The control method according to claim 1, characterized in that: In S2, if the mass flow sensor that obtains the actual value of the mass flow fails, is 0; if the pressure sensor that obtains the actual pressure value fails, then set e p is 0.

3. The control method according to claim 1, characterized in that: Get the air compressor speed feedforward reference value n ref The method is: Conducting an experimental test, obtaining steady-state values ​​of air intake mass flow rate and pressure under different air compressor speeds as effective values, and obtaining a first test data matrix, wherein the first test data matrix includes 3 columns of data, respectively representing the air compressor speed, the air intake mass flow rate, and the air intake pressure; The three columns of data in the first test data matrix are used as input data for the X-axis, Y-axis, and Z-axis, and surface interpolation and fitting are performed to obtain the air compressor speed feedforward reference value n ref about and p req 2D feedforward data table based on the compressor speed feedforward reference value n ref about and p req 2D feedforward data table to obtain the compressor speed feedforward reference value n ref .

4. The control method according to claim 1, characterized in that: The throttle opening feedforward reference value θ ref The method to obtain is: The experimental test is carried out, and the steady-state values ​​of the air intake mass flow rate and pressure under different throttle openings are selected as effective values ​​to obtain a second test data matrix, which includes 3 columns of data, namely, throttle opening, air intake mass flow rate and air intake pressure. The three columns of data of the second test data matrix are respectively the input data of the X-axis, Y-axis and Z-axis, and the surface interpolation and fitting are performed to obtain the throttle opening feedforward reference value θ ref about and p req The 2D feedforward data table is based on the throttle opening feedforward reference value θ ref about and p req 2D feedforward data table, and obtain the throttle opening feedforward reference value θ ref .

5. The control method according to claim 2, characterized in that: The method to determine whether the sensor is failed is: Step ①: Set the sensor failure flag SensorFaultFlag and the controller I / O port power supply fault flag MCUPwrErrFlg to 0; Step ②: Obtain the sensor signal in real time and determine whether it is within the sensor signal range. If it is within the range, jump to step ③; if it is not within the range, jump to step ④; Step ③: Set SensorFaultFlag = 0, enter the next sampling time point, and return to step ②; Step ④: Determine whether the controller I / O port pin power supply voltage MCUPinVltg is greater than the voltage threshold VltgThreshold, if so, jump to step ⑤, if less, jump to step ⑥; Step ⑤: Set SensorFaultFlag = 1, enter the next sampling time point, and return to step ②; Step ⑥: Set MCUPwrErrFlg = 1, enter the next sampling time point, and return to step ②; If SensorFaultFlg=0, the sensor is not failed, and if SensorFaultFlg=1, the sensor is failed, and the sensor is a mass flow sensor or a pressure sensor.

6. The control method according to claim 1, characterized in that: The method further comprises the following steps: S6: according to the throttle opening request value θ req And the actual value of air compressor speed n act ; Get the air compressor speed control error e n , according to the air compressor speed request value n req and the actual throttle opening value θ act , get the throttle opening control error e θ ; S7, the air compressor speed control error e n and throttle opening control error e θ The signals are input to the air compressor speed controller and the throttle opening controller respectively, and the execution action signals of the air compressor and the throttle are output, thereby realizing the closed-loop control of the air compressor speed and the throttle opening.

7. The control method according to claim 2, characterized in that: The equation for the mass flow PID controller is: Where: k p1 is the proportional control coefficient of the mass flow PID controller, k i1 is the integral control coefficient of the mass flow PID controller, k d1 is the differential control coefficient of the mass flow PID controller, e1(t) is the mass flow control error at the current moment, and u1(t) is the output value of the mass flow PID controller.

8. The control method according to claim 2, characterized in that: The equation for the pressure PID controller is: Where: k p2 is the proportional control coefficient of the pressure PID controller, k i2 is the integral control coefficient of the pressure PID controller, k d2 is the differential control coefficient of the pressure PID controller, e2(t) is the pressure control error at the current moment, and u2(t) is the output value of the pressure PID controller.

9. A control system for a fuel cell engine air supply system based on the control method according to any one of claims 1 to 8, characterized in that: include: The feedforward reference value acquisition module is configured to be based on the actual value of the fuel cell output current I act , obtain the air intake mass flow request value under the current fuel cell operating current and pressure request value p req , and after processing, the air compressor speed feedforward reference value n is obtained ref and the throttle opening feedforward reference value θ ref ; Difference acquisition module, configured to receive the actual value of mass flow and the actual pressure value p act , and obtain the mass flow control error And the pressure control error e p , and the mass flow control error And the pressure control error e p Input into the mass flow PID controller and pressure PID controller respectively; The decoupler is configured to receive the output results of the mass flow PID controller and the pressure PID controller to obtain the air compressor speed compensation value n c and throttle angle compensation value θ c ; The decoupling method of the decoupler is based on the discrete transfer function matrix The discrete transfer function matrix Obtained by the following method: The transfer function matrix is ​​obtained according to the following formula: The transfer function matrix in the form of a continuous transfer function Discretization processing is performed; Where: G 11 (S) represents the first-order transfer function of the air intake mass flow rate relative to the compressor speed step signal; G 21 (S) represents the first-order transfer function of air intake pressure relative to the compressor speed step signal; G 12 (S) represents the first-order transfer function of the air intake mass flow rate relative to the throttle opening step signal; G 22 (S) represents the first-order transfer function of the air intake pressure relative to the throttle opening step signal; The request value acquisition module is configured to feed forward the air compressor speed reference value n ref Compensation value n for air compressor speed c The sum is the air compressor speed request value n req , the throttle opening feedforward reference value θ ref and throttle angle compensation value θ c The sum is the throttle opening request value θ req , and n req and θ req They are input into the air compressor speed control loop and the throttle opening control loop respectively.

10. The system according to claim 9, characterized in that: The sensor judgment module is also included, which is configured to judge whether the mass flow sensor and the pressure sensor are invalid. If the mass flow sensor that obtains the actual value of the mass flow fails, is 0 and is input into the mass flow PID controller; if the pressure sensor that obtains the actual pressure value fails, then let e p is 0 and is input into the pressure PID controller.

11. The system according to claim 10, characterized in that: The judgment method of the sensor judgment module is: Step ①: Set the sensor failure flag SensorFaultFlag and the controller I / O port power supply fault flag MCUPwrErrFlg to 0; Step ②: Obtain the sensor signal in real time and determine whether it is within the sensor signal range. If it is within the range, jump to step ③; if it is not within the range, jump to step ④; Step ③: Set SensorFaultFlag = 0, enter the next sampling time point, and return to step ②; Step ④: Determine whether the controller I / O port pin power supply voltage MCUPinVltg is greater than the voltage threshold VltgThreshold, if so, jump to step ⑤, if less, jump to step ⑥; Step ⑤: Set SensorFaultFlag = 1, enter the next sampling time point, and return to step ②; Step ⑥: Set MCUPwrErrFlg = 1, enter the next sampling time point, and return to step ②; If SensorFaultFlg=0, the sensor is not failed, and if SensorFaultFlg=1, the sensor is failed, and the sensor is a mass flow sensor or a pressure sensor.

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