Fuel cell thermal management system for heavy load change working condition

Abstract

The invention relates to a fuel cell thermal management system for a heavy-load change working condition, and belongs to the technical field of fuel cells. According to the system, a galvanic pile unit comprises a galvanic pile cooling path inlet temperature sensor, a galvanic pile cooling path outlet temperature sensor, a current output sensor and a voltage output sensor which are used for collecting galvanic pile cooling path inlet and outlet temperature and output current and voltage respectively; the controller is used for presetting the target temperature of the cooling liquid at the outlet of the electric pile and calculating the opening value of the electronic thermostat through a cascade internal model control algorithm in combination with the inlet and outlet temperatures so as to control the opening of the electronic thermostat; an optimal working temperature threshold value is preset, outlet temperature grades are divided, and a heat dissipation unit is controlled according to the outlet temperature grades; working current is preset, the required cooling liquid flow is calculated through a measuring and calculating model in combination with output voltage and inlet and outlet temperatures, rotating speed data is calculated according to the flow-efficiency-rotating speed characteristics of the electronic centrifugal pump, rotating speed grades are divided, and operation of the electronic centrifugal pump is controlled; and controlling the PTC heater to start and stop according to the target and outlet temperature judgment result. And efficient fuel cell thermal management control is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and particularly relates to a fuel cell thermal management system for large load change conditions. Background Art

[0002] Temperature is an important factor affecting the output performance and durability of proton exchange membrane fuel cells. Under normal operating conditions of fuel cells, the electrical efficiency is 40% - 60%, and the remaining energy is transferred in the form of heat. In order to improve the comprehensive thermoelectric efficiency of fuel cells, good thermal management technology is very necessary. On the other hand, the heat sources of fuel cells mainly come from the entropy heat of the oxidation-reduction reaction of hydrogen and oxygen, irreversible electrochemical reaction heat, ohmic heat of current transmission, and latent heat of phase change of water. If the stack cannot be cooled well in time, the system temperature will continue to rise, resulting in serious dry membrane phenomenon of the proton membrane, accelerating catalyst decay, and even local hot spots, causing irreversible damage to the membrane and generating perforations, thus triggering direct contact between hydrogen and oxygen and bringing serious safety hazards. Therefore, a set of efficient thermal management system is needed to maintain the thermal balance of the fuel cell system, enable the stack to quickly reach the normal operating temperature range, and ensure the best working state on both the cathode and anode sides.

[0003] Although related technical research has achieved the expected control goal to a certain extent, and can control the battery temperature within the set range under certain working conditions, it cannot effectively control the system temperature of high-power fuel cells for commercial vehicles under large load change conditions. Since the heat transfer process of the fuel cell thermal management system is highly nonlinear and has a large time delay, it has high requirements for the robustness and responsiveness of the thermal management system under high-power change conditions. Therefore, the aforementioned efficient thermal management system is needed to quickly and accurately track the target temperature of the fuel cell stack, thereby improving the comprehensive performance of the fuel cell system and extending the life of the stack. Summary of the Invention

[0004] To solve the above problems existing in the prior art, the present invention provides a fuel cell thermal management system for large load change conditions, including: a stack unit, an electronic thermostat, a heat dissipation unit, and a controller;

[0005] The stack unit includes a stack cooling circuit inlet temperature sensor, a stack cooling circuit outlet temperature sensor, a stack current output sensor, and a stack voltage output sensor. The stack cooling circuit inlet temperature sensor is used to collect the temperature at the inlet of the stack cooling circuit, the stack cooling circuit outlet temperature sensor is used to collect the temperature at the outlet of the stack cooling circuit, the stack current output sensor is used to collect the stack output current, and the stack voltage output sensor is used to collect the stack output voltage;

[0006] The controller is used to preset the target temperature of the coolant at the stack outlet, calculate the opening value of the electronic thermostat through a cascade internal model control algorithm based on the target temperature of the coolant at the stack outlet, the inlet temperature of the stack cooling circuit, and the outlet temperature of the stack cooling circuit, and generate an adaptive signal according to the opening value of the electronic thermostat to control the change of the opening of the electronic thermostat; preset the optimal operating temperature threshold of the stack, classify the outlet temperature of the stack cooling circuit according to the preset optimal operating temperature threshold of the stack to obtain the outlet temperature level, and generate an adaptive signal according to the outlet temperature level to control the operation of the heat dissipation unit; preset the operating current of the stack, calculate the required coolant flow through a measurement model based on the operating current, the output voltage of the stack, the inlet temperature of the stack cooling circuit, and the outlet temperature of the stack cooling circuit, obtain the flow - efficiency - speed characteristic of the electronic centrifugal pump, calculate the rotational speed data of the electronic centrifugal pump according to the flow - efficiency - speed characteristic and the required coolant flow, preset the rotational speed division threshold, classify the rotational speed data of the electronic centrifugal pump according to the rotational speed division threshold to obtain the rotational speed level of the electronic centrifugal pump, and generate an adaptive signal according to the rotational speed level of the electronic centrifugal pump to control the operation of the electronic centrifugal pump; judge according to the target temperature of the coolant at the stack outlet and the outlet temperature of the stack cooling circuit to obtain a judgment result, and generate an adaptive signal according to the judgment result to control the start and stop of the PTC heater.

[0007] Specifically, the heat dissipation unit includes a first radiator and a second radiator. Both the first radiator and the second radiator are composed of a heat dissipation flow channel and a heat dissipation fan. The heat dissipation flow channel is used for convective heat transfer between the coolant and the surrounding environment. The controller controls the operation of the heat dissipation fan through an adaptive signal to achieve the heat dissipation amount of the coolant in the large - circulation coolant branch.

[0008] Specifically, the large - circulation coolant branch is composed of an electronic thermostat, the first radiator, the second radiator, and a three - way valve.

[0009] Specifically, the specific calculation steps of the cascade internal model control algorithm include:

[0010] Obtain the internal - model simulated stack outlet coolant temperature, calculate the first temperature difference according to the internal - model simulated stack outlet coolant temperature and the stack cooling circuit outlet temperature, and calculate the target temperature of the coolant at the stack inlet through a first - order time - domain relationship according to the target temperature of the coolant at the stack outlet and the first temperature difference.

[0011] The expression of the first - order time - domain relationship is:

[0012]

[0013] where, Tst,in_target (s) is the target temperature of the coolant at the inlet of the stack, T outer is the time constant of the internal model of the outer loop, s is the Laplace transform variable, K outer is the gain of the internal model of the outer loop, T f,outer is the time constant of the filter, T st,out_target(s) is the target temperature of the coolant at the outlet of the stack, E outer(s) The first temperature difference;

[0014] Obtain the temperature of the coolant at the inlet of the stack simulated by the internal model, calculate the second temperature difference according to the temperature of the coolant at the inlet of the stack simulated by the internal model and the temperature at the inlet of the stack cooling path, and calculate the opening value of the electronic thermostat according to the second temperature difference and the target temperature of the coolant at the inlet of the stack through the second time domain relationship.

[0015] The expression of the second time domain relationship is:

[0016]

[0017] where, α actuactor(s) is the opening value of the electronic thermostat, T inner is the time constant of the internal model of the inner loop, s is the Laplace transform variable, K inner is the gain of the internal model of the inner loop, T f，inner is the time constant of the filter, T st,in_target(s) is the target temperature of the coolant at the inlet of the stack, E inner(s) is the second temperature difference.

[0018] Specifically, it further includes a small-circulation coolant branch, and the small-circulation coolant branch is composed of an electronic thermostat, a PTC heater, and a three-way valve.

[0019] Specifically, the grading of the outlet temperature of the stack cooling path according to the preset optimal operating temperature threshold of the stack specifically includes:

[0020] The optimal operating temperature threshold of the stack includes a first temperature threshold and a second temperature threshold;

[0021] The outlet temperature grade includes a low-temperature section, a medium-temperature section, and a high-temperature section;

[0022] When the outlet temperature of the stack cooling path is not greater than the first temperature threshold, output the outlet temperature grade as the low-temperature section;

[0023] When the outlet temperature of the stack cooling path is greater than the first temperature threshold and not greater than the second temperature threshold, output the outlet temperature grade as the medium-temperature section;

[0024] When the temperature at the outlet of the stack cooling circuit is greater than the second temperature threshold, output that the outlet temperature level is the high-temperature section.

[0025] Specifically, the expression of the measurement model is:

[0026]

[0027] where m cl,req is the required coolant flow rate, Q heat is the heat generated by the system, C cl is the specific heat capacity of the coolant, T st,out is the temperature at the outlet of the stack cooling circuit, T st,in is the temperature at the inlet of the stack cooling circuit, N cell is the number of single cells in the stack, I st is the working current, F is the Faraday constant, H react is the enthalpy of hydrogen-oxygen reaction, V st is the output voltage of the stack.

[0028] Specifically, the judgment result obtained by judging according to the target temperature of the coolant at the outlet of the stack and the temperature at the outlet of the stack cooling circuit includes:

[0029] The judgment result includes the PTC heater being turned on and the PTC heater being turned off;

[0030] When the temperature at the outlet of the stack cooling circuit is not less than the target temperature of the coolant at the outlet of the stack, output that the judgment result is the PTC heater being turned off;

[0031] When the temperature at the outlet of the stack cooling circuit is less than the target temperature of the coolant at the outlet of the stack, output that the judgment result is the PTC heater being turned on.

[0032] Specifically, the classification of the electronic centrifugal pump speed data according to the rotation speed division threshold to obtain the electronic centrifugal pump speed level includes:

[0033] The electronic centrifugal pump level includes level one and level two;

[0034] When the electronic centrifugal pump speed data is less than the rotation speed division threshold, output that the electronic centrifugal pump speed level is level one;

[0035] When the electronic centrifugal pump speed data is not less than the rotation speed division threshold, output that the electronic centrifugal pump speed level is level two.

[0036] An electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the fuel cell thermal management system for large load change conditions as described above.

[0037] A storage medium containing computer-executable instructions, which are used to execute the fuel cell thermal management system for large load change conditions as described above when executed by a computer processor.

[0038] The beneficial effects of the present invention are as follows:

[0039] (1) By using an electronic thermostat with a faster response speed and more precise control as the main actuator and adopting a cascade internal model control algorithm with strong robustness and strong stability to control the main actuator, the overall response performance and anti-interference ability of the thermal management system are effectively improved. Under the condition of large power load changes, better temperature tracking control can be achieved, and the coolant temperature at the outlet of the stack can strictly and stably track the target temperature.

[0040] (2) By decoupling the control of the fan and the electronic centrifugal pump using current feedforward control and hierarchical control, the overshoot is effectively reduced, thereby further improving the response characteristics of the fuel cell system and enhancing the stability of the system. When the power of the stack fluctuates greatly, the stack can also respond quickly and accurately and keep the coolant temperature at the outlet of the stack within a small range near the target temperature.

[0041] (3) By providing a cascade internal model control algorithm, the structure of this control algorithm is simple and easy to debug. Since the time constants in the inner loop controller and the outer loop controller in the cascade internal model control loop of the present invention are taken as an equal value, only one parameter needs to be debugged under the reasonable setting of the internal model to adjust the response characteristics of the system. Description of the Drawings

[0042] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the drawings.

[0043] Figure 1 is a schematic structural diagram of the fuel cell thermal management system for large load change conditions of the present invention;

[0044] Figure 2 is a schematic control network diagram of the fuel cell thermal management system for large load change conditions in the present invention. Detailed Embodiments

[0045] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following will, in conjunction with the drawings and preferred embodiments, describe in detail the specific embodiments, structures, features, and effects of the present invention.

[0046] Please refer to Figure 1-2 , a fuel cell thermal management system for large load change conditions, including a stack unit, an electronic thermostat, a heat dissipation unit, and a controller;

[0047] The fuel cell unit includes a fuel cell cooling circuit inlet temperature sensor, a fuel cell cooling circuit outlet temperature sensor, a fuel cell current output sensor, and a fuel cell voltage output sensor. The fuel cell cooling circuit inlet temperature sensor is used to collect the inlet temperature of the fuel cell cooling circuit. The fuel cell cooling circuit outlet temperature sensor is used to collect the outlet temperature of the fuel cell cooling circuit. The fuel cell current output sensor is used to collect the output current of the fuel cell. The fuel cell voltage output sensor is used to collect the output voltage of the fuel cell;

[0048] The controller is used to preset the target temperature of the coolant at the fuel cell outlet, calculate the opening value of the electronic thermostat according to the target temperature of the coolant at the fuel cell outlet, the inlet temperature of the fuel cell cooling circuit, and the outlet temperature of the fuel cell cooling circuit through a cascade internal model control algorithm, and generate an adaptive signal according to the opening value of the electronic thermostat to control the change of the opening of the electronic thermostat; preset the optimal operating temperature threshold of the fuel cell, classify the outlet temperature of the fuel cell cooling circuit according to the preset optimal operating temperature threshold of the fuel cell to obtain the outlet temperature level, and generate an adaptive signal according to the outlet temperature level to control the operation of the heat dissipation unit; preset the operating current of the fuel cell, calculate the required coolant flow rate through a measurement model according to the operating current, the output voltage of the fuel cell, the inlet temperature of the fuel cell cooling circuit, and the outlet temperature of the fuel cell cooling circuit, obtain the flow - efficiency - speed characteristic of the electronic centrifugal pump, calculate the rotational speed data of the electronic centrifugal pump according to the flow - efficiency - speed characteristic and the required coolant flow rate, preset the rotational speed division threshold, classify the rotational speed data of the electronic centrifugal pump according to the rotational speed division threshold to obtain the rotational speed level of the electronic centrifugal pump, and generate an adaptive signal according to the rotational speed level of the electronic centrifugal pump to control the operation of the electronic centrifugal pump; judge according to the target temperature of the coolant at the fuel cell outlet and the outlet temperature of the fuel cell cooling circuit to obtain a judgment result, and generate an adaptive signal according to the judgment result to control the start and stop of the PTC heater.

[0049] In this embodiment, the fuel cell unit further includes a fuel cell, which is used for the electrochemical reaction of hydrogen and air. The electronic centrifugal pump is used to adjust the coolant circulation flow rate of the system. The electronic thermostat includes an electronic thermostat inlet, a first outlet of the electronic thermostat, and a second outlet of the electronic thermostat. The controller controls the opening of the electronic thermostat through an adaptive signal, and further controls the coolant flow rate ratio between the first outlet of the electronic thermostat and the second outlet of the electronic thermostat; the flow - efficiency - speed characteristic is used to represent the proportional relationship among the flow rate, the best pump efficiency, and the rotational speed of the electronic centrifugal pump.

[0050] In this embodiment, the fuel cell thermal management system for large load change conditions includes a large cycle and a small cycle. The large cycle is used to achieve system heat dissipation, and the small cycle is used to adjust the coolant temperature at the inlet of the fuel cell stack. The flow ratio between the large cycle and the small cycle is adjusted by a thermostat.

[0051] Specifically, the heat dissipation unit includes a first radiator and a second radiator. Both the first radiator and the second radiator are composed of a heat dissipation flow channel and a heat dissipation fan. The heat dissipation flow channel is used for convective heat transfer between the coolant and the surrounding environment. The controller controls the operation of the heat dissipation fan through an adaptive signal to achieve the heat dissipation amount of the coolant in the large cycle coolant branch.

[0052] Specifically, the large cycle coolant branch is composed of an electronic thermostat, the first radiator, the second radiator, and a three-way valve. The specific connection method is that the first outlet of the electronic thermostat is connected to the inlet of the first radiator, the inlet of the first radiator is connected to the inlet of the second radiator, and the inlet of the second radiator is connected to the first inlet of the three-way valve.

[0053] Specifically, the specific calculation steps of the cascade internal model control algorithm include:

[0054] Obtain the internal model simulated coolant temperature at the outlet of the fuel cell stack. Calculate the first temperature difference based on the internal model simulated coolant temperature at the outlet of the fuel cell stack and the coolant temperature at the outlet of the fuel cell cooling circuit. Calculate the target coolant temperature at the inlet of the fuel cell stack through the first time-domain relationship based on the target coolant temperature at the outlet of the fuel cell stack and the first temperature difference.

[0055] The expression of the first time-domain relationship is:

[0056]

[0057] where, T st,in_target (s) is the target coolant temperature at the inlet of the fuel cell stack, T outer is the internal model time constant of the outer loop, s is the Laplace transform variable, K outer is the internal model gain of the outer loop, T f,outer is the filter time constant, T st,out_target(s) is the target coolant temperature at the outlet of the fuel cell stack, E outer(s) the first temperature difference;

[0058] Obtain the internal model simulated coolant temperature at the inlet of the fuel cell stack. Calculate the second temperature difference based on the internal model simulated coolant temperature at the inlet of the fuel cell stack and the coolant temperature at the inlet of the fuel cell cooling circuit. Calculate the opening value of the electronic thermostat through the second time-domain relationship based on the second temperature difference and the target coolant temperature at the inlet of the fuel cell stack.

[0059] The expression of the second time-domain relationship is:

[0060]

[0061] where α actuactor(s) is the opening value of the electronic thermostat, T inner is the internal model time constant of the inner loop, s is the Laplace transform variable, K inner is the internal model gain of the inner loop, T f，inner is the filter time constant, T st,in_target(s) is the target temperature of the coolant at the inlet of the stack, E inner(s) is the second temperature difference.

[0062] In this embodiment, the range of the opening value of the electronic thermostat is 0 to 85. When the opening value of the electronic thermostat is 0, the coolant enters the stack through the small circulation cooling branch; when the opening of the electronic thermostat is 85, the coolant enters the stack through the large circulation cooling branch; when the opening value of the electronic thermostat is greater than 0 and less than 85, at this time the coolant can enter the stack from both the large circulation cooling branch and the small circulation cooling branch.

[0063] Specifically, it further includes a small circulation coolant branch, and the small circulation coolant branch is composed of an electronic thermostat, a PTC heater, and a three-way valve. The specific connection method is that the second outlet of the electronic thermostat is connected to the inlet of the PTC heater, and the inlet of the PTC heater is connected to the second inlet of the three-way valve.

[0064] Specifically, the grading of the outlet temperature of the stack cooling path according to the preset optimal operating temperature threshold of the stack to obtain the outlet temperature grade specifically includes:

[0065] The optimal operating temperature threshold of the stack includes a first temperature threshold and a second temperature threshold;

[0066] The outlet temperature grade includes a low temperature section, a medium temperature section, and a high temperature section;

[0067] When the outlet temperature of the stack cooling path is not greater than the first temperature threshold, the outlet temperature grade is output as the low temperature section;

[0068] When the outlet temperature of the stack cooling path is greater than the first temperature threshold and not greater than the second temperature threshold, the outlet temperature grade is output as the medium temperature section;

[0069] When the outlet temperature of the stack cooling path is greater than the second temperature threshold, the outlet temperature grade is output as the high temperature section.

[0070] Specifically, the expression of the measurement model is:

[0071]

[0072]

[0073] where m cl,req is the required coolant flow rate, Q heat is the heat generated by the system, C cl is the specific heat capacity of the coolant, T st,out is the outlet temperature of the fuel cell stack cooling circuit, T st,in is the inlet temperature of the fuel cell stack cooling circuit, N cell is the number of single cells in the fuel cell stack, I st is the working current, F is the Faraday constant, H react is the enthalpy of hydrogen-oxygen reaction, V st is the output voltage of the fuel cell stack.

[0074] Specifically, the determination result obtained by making a determination based on the target temperature of the coolant at the outlet of the fuel cell stack and the outlet temperature of the fuel cell stack cooling circuit includes:

[0075] The determination result includes turning on the PTC heater and turning off the PTC heater;

[0076] When the outlet temperature of the fuel cell stack cooling circuit is not less than the target temperature of the coolant at the outlet of the fuel cell stack, output the determination result as turning off the PTC heater;

[0077] When the outlet temperature of the fuel cell stack cooling circuit is less than the target temperature of the coolant at the outlet of the fuel cell stack, output the determination result as turning on the PTC heater.

[0078] Specifically, the classification of the electronic centrifugal pump speed data into grades according to the rotation speed classification threshold includes:

[0079] The grades of the electronic centrifugal pump include grade one and grade two;

[0080] When the electronic centrifugal pump speed data is less than the rotation speed classification threshold, output the grade of the electronic centrifugal pump as grade one;

[0081] When the electronic centrifugal pump speed data is not less than the rotation speed classification threshold, output the grade of the electronic centrifugal pump as grade two.

[0082] Next, refer to Figure 1A fuel cell thermal management system of the present invention is described in detail, which includes: a stack 1, a controller 2, a main pipeline of the system coolant circulation 3, an electronic thermostat 4, a large-circulation coolant branch 5, a cooling fan 6, a heat dissipation channel 7, a pipeline of the large-circulation coolant branch 8, a heat dissipation channel 9, a cooling fan 10, a pipeline of the large-circulation coolant branch 11, a pipeline of the small-circulation coolant branch 12, a PTC heater 13, a pipeline of the small-circulation coolant branch 14, a three-way valve 15, a coolant circulation main pipeline 16, an electronic centrifugal pump 17, a main pipeline of the system coolant circulation 18, a stack cooling path inlet temperature sensor 19, a stack cooling path outlet temperature sensor 20, a stack current output sensor 21, and a stack voltage output sensor 22.

[0083] The fuel cell thermal management system of the present invention provides a thermal management control strategy as Figure 2 shown:

[0084] During the actual operation process, the stack 1 needs to be quickly heated to a suitable working temperature in the initial stage after startup. The controller 2 controls the electronic thermostat 4 and the PTC heater 13 to heat the circulating coolant. The heated coolant returns to the coolant pipeline inside the stack 1 through the system pipeline and exchanges heat with the stack 1, so that the stack 1 can reach the optimal working temperature as soon as possible. As the power of the stack 1 increases, correspondingly, its heat generation increases and the temperature rises, and effective heat dissipation of the stack 1 is required. At this time, the current output signal of the stack 1 and the coolant temperature signals at the inlet and outlet of the stack 1 are respectively fed back to the controller 2 by the current output sensor 21, the stack cooling path inlet temperature sensor 19, and the stack cooling path outlet temperature sensor 20. The controller 2 calculates, processes, and analyzes and judges these signals, and finally obtains a control signal and outputs it to the corresponding actuator, thereby adjusting the working states of the actuators to dissipate heat from the stack 1 in a timely manner.

[0085] It should be noted that as Figure 1As shown in the figure, the present invention uses the electronic thermostat 4 as the main actuator. When the coolant temperature at the outlet of the fuel cell stack 1 is higher than the target temperature, the temperature sensors 19 at the inlet and 20 at the outlet of the fuel cell stack cooling circuit feed back the temperature signals at the inlet and outlet of the fuel cell stack 1 to the controller 2. The controller 2 calculates the adjustment trend and amplitude of the electronic thermostat 4 through the cascade internal model algorithm and outputs the signal to the electronic thermostat 4, guiding it to execute the instruction of increasing the opening degree according to the control signal, so that the coolant flow rate for heat dissipation through the large-circulation coolant branch increases, thereby increasing the system heat dissipation and quickly reducing the temperature of the fuel cell stack 1 to the target temperature. When the coolant temperature at the outlet of the fuel cell stack 1 is lower than the target temperature, the controller 2 calculates the adjustment trend and amplitude of the electronic thermostat 4 through the cascade internal model control algorithm according to the feedback signals of the coolant temperatures at the inlet and outlet of the fuel cell stack 1 and outputs the signal to the electronic thermostat 4, guiding it to execute the instruction of reducing the opening degree according to the control signal, so that the coolant flow rate for heat dissipation through the large-circulation coolant branch decreases, thereby reducing the system heat dissipation and quickly increasing the temperature of the fuel cell stack 1 to the target temperature. Specifically, the cascade internal model control structure adopted and designed in the present invention is as shown in Figure 2 and includes two-level internal model control of an inner loop and an outer loop. Among them, the inner-loop system model is the part in the thermal management system that takes the opening degree of the electronic thermostat as the input and the coolant temperature at the inlet of the fuel cell stack as the output. The inner-loop internal model is obtained by system identification and adjustment of the inner-loop system model. The outer-loop system model is the part in the thermal management system that takes the coolant temperature at the inlet of the fuel cell stack as the input and the coolant temperature at the outlet of the fuel cell stack as the output. The outer-loop internal model is obtained by system identification and adjustment of the outer-loop system model. The controllers of the inner loop and the outer loop are both composed of the inverse of their corresponding internal models and an n-order filter in the form of , where the value of n needs to ensure that the order of the denominator of the controller is not less than that of the numerator. To simplify the system, n is taken as the difference between the order of the denominator and the order of the numerator of the corresponding internal model. T f is the time constant of the controller, and its value needs to ensure that the poles of the controller are all in the left half complex plane. To further simplify the algorithm structure for debugging, the time constants in the inner-loop controller and the outer-loop controller are taken as an equal value. Under the reasonable setting of the internal model, only one parameter T f needs to be debugged to adjust the response characteristics of the system.

[0086] During the actual operation process, the target coolant temperature at the outlet of the fuel cell stack is set by the operator. The signal obtained by subtracting the actual coolant temperature at the outlet of the fuel cell stack output by the fuel cell thermal management system of the present invention, that is, the deviation between the actual coolant temperature at the outlet of the fuel cell stack fed back by the temperature sensor and the inner-model simulated coolant temperature at the outlet of the fuel cell stack output by the outer-loop internal model, is processed by the calculation of the outer-loop controller to obtain the target coolant temperature signal at the inlet of the fuel cell stack and enters the inner-loop circuit. The inner-loop circuit is as shown in Figure 2As shown in the dashed box, it is a typical internal model control structure. The target coolant temperature signal at the inlet of the fuel cell stack passes through the inner loop controller to obtain the opening control signal of the electronic thermostat and outputs it to the electronic thermostat 4 to adjust its opening, thereby controlling the coolant flow ratio through the large and small cycle coolant branches and the heat dissipation of the system.

[0087] During the actual operation process, the first radiator fan 6 and the second radiator fan 10 are logically judged and classified according to the feedback signal of the temperature sensor 20 at the outlet of the fuel cell stack cooling circuit by the controller 2 according to the formulated classification rules, so as to judge the control strategies of the first radiator fan 6 and the second radiator fan 10 corresponding to the classification rules under this working condition. The control strategy is to keep closed or to perform calculation processing by the feedforward of the fuel cell stack current output signal to obtain the radiator fan speed signal, and finally to realize the decoupled control of the first radiator fan 6, the second radiator fan 10 and the electronic thermostat 4. Preferably, the feedback signal of the temperature sensor 20 at the outlet of the fuel cell stack cooling circuit can be divided into three consecutive temperature ranges: low temperature range (the coolant temperature at the outlet of the fuel cell stack is much lower than the optimal operating temperature of the fuel cell stack), medium temperature range (the coolant temperature at the outlet of the fuel cell stack is within a certain appropriate range not exceeding the optimal operating temperature of the fuel cell stack), and high temperature range (the coolant temperature at the outlet of the fuel cell stack exceeds the optimal operating temperature of the fuel cell stack). In the low temperature range, both the first radiator fan 6 and the second radiator fan 10 are kept closed to promote the rapid increase of the fuel cell stack temperature to the optimal operating temperature; in the medium temperature range, the first radiator fan 6 is turned on and operates under the feedforward control of the controller 2 following the current output signal with a certain transfer function, and the second radiator fan 10 is kept closed, thereby preventing the fuel cell stack temperature from rising too fast and causing a large overshoot; in the high temperature range, both the first radiator fan 6 and the second radiator fan 10 operate under the feedforward control of the controller 2 following the current output signal with a certain transfer function, thereby ensuring to meet the maximum heat dissipation requirement of the system, and then the electronic thermostat 4 can be used for precise control to achieve the decoupling effect.

[0088] During the actual operation process, the electronic centrifugal pump 17 is calculated and processed by the controller 2 based on the feedback signals of the temperature sensor 19 at the inlet of the fuel cell stack cooling circuit and the temperature sensor 20 at the outlet of the fuel cell stack cooling circuit and its own speed state to obtain the ideal flow rate signal required for heat dissipation, and then the speed signal is obtained according to the flow rate - speed classification rules formulated based on the best efficiency according to the flow rate - efficiency - speed characteristics corresponding to the electronic centrifugal pump 17 and output to the electronic centrifugal pump 17 to change its speed, thereby controlling the circulating coolant flow rate, the heat dissipation of the cooling pipeline in the fuel cell stack 1, and the coolant temperature difference between the inlet and outlet of the fuel cell stack 1.

[0089] In summary, the present invention can effectively decouple multiple actuators, and when the electronic centrifugal pump 17, the first cooling fan 6, and the second cooling fan 10 all meet the system cooling requirements, the high responsiveness and high precision of the electronic thermostat 4 and the strong robustness of the cascade internal model control algorithm are utilized to achieve efficient fuel cell thermal management control, thereby effectively improving the comprehensive performance and durability of the fuel cell stack 1.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention in detail. However, this application is not limited to the above embodiments. It should be understood that within the scope of knowledge in the technical field, those skilled in the art can modify or equivalently replace the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

[0091] The computer storage medium of the embodiments of the present invention can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the computer-readable storage medium include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, the computer-readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, apparatus, or device.

[0092] The computer-readable signal medium can include a data signal propagated in a baseband or as part of a carrier wave, which carries the computer-readable program code. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The computer-readable signal medium can also be any computer-readable medium other than the computer-readable storage medium, and this computer-readable medium can send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device.

[0093] The program code contained on a computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wire, optical fiber cable, RF, etc., or any suitable combination of the foregoing. The computer program code for performing the operations of the present invention can be written in one or more programming languages or combinations thereof, the programming languages including object-oriented programming languages such as Java, Smalltalk, C++, and also including conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or, alternatively, can be connected to an external computer (e.g., using an Internet service provider to connect through the Internet).

[0094] As described above, only the preferred embodiments of the present invention are given, and there is no limitation to the present invention in any form. Although the present invention has been disclosed as above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A fuel cell thermal management system for large load change conditions, characterized in that: include: Battery stack unit, electronic thermostat, cooling unit, controller; The stack unit includes a stack cooling path inlet temperature sensor, a stack cooling path outlet temperature sensor, a stack current output sensor, and a stack voltage output sensor. The stack cooling path inlet temperature sensor is used to collect the stack cooling path inlet temperature, the stack cooling path outlet temperature sensor is used to collect the stack cooling path outlet temperature, the stack current output sensor is used to collect the stack output current, and the stack voltage output sensor is used to collect the stack output voltage; The controller is used to preset a target temperature of the coolant at the outlet of the stack, calculate an opening value of the electronic thermostat based on the cascade internal model control algorithm according to the target temperature of the coolant at the outlet of the stack, the inlet temperature of the stack cooling path, and the outlet temperature of the stack cooling path, and generate an adaptive signal to control the change of the opening of the electronic thermostat according to the opening value of the electronic thermostat; preset an optimal operating temperature threshold of the stack, classify the outlet temperature of the stack cooling path according to the preset optimal operating temperature threshold of the stack to obtain an outlet temperature grade, and generate an adaptive signal to control the operation of the heat dissipation unit according to the outlet temperature grade; preset an operating current of the stack, and calculate the operating current, the output voltage of the stack, the inlet temperature of the stack cooling path, and the outlet temperature of the stack cooling path according to the output voltage of the stack. The outlet temperature of the stack cooling path is calculated through a measurement model to obtain the required coolant flow rate, and the flow-efficiency-speed characteristics of the electronic centrifugal pump are obtained. The speed data of the electronic centrifugal pump is calculated based on the flow-efficiency-speed characteristics and the required coolant flow rate. A speed division threshold is preset, and the speed data of the electronic centrifugal pump is graded according to the speed division threshold to obtain the speed grade of the electronic centrifugal pump. According to the speed grade of the electronic centrifugal pump, an adaptive signal is generated according to the speed grade of the electronic centrifugal pump to control the operation of the electronic centrifugal pump; a judgment result is obtained based on the target temperature of the coolant at the outlet of the fuel cell stack and the outlet temperature of the fuel cell stack cooling path, and an adaptive signal is generated according to the judgment result to control the start and stop of the PTC heater.

2. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: The heat dissipation unit includes a first radiator and a second radiator, both of which are composed of a heat dissipation channel and a heat dissipation fan, the heat dissipation channel is used for convective heat exchange between the coolant and the surrounding environment, and the controller controls the operation of the heat dissipation fan through an adaptive signal to achieve the heat dissipation of the coolant in the large-circulation coolant branch.

3. The fuel cell thermal management system for large load change conditions according to claim 2, characterized in that: The large circulation coolant branch is composed of an electronic thermostat, the first radiator, the second radiator, and a three-way valve.

4. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: The specific calculation steps based on the cascade internal model control algorithm include: The internal model simulates the outlet coolant temperature of the stack, and calculates a first temperature difference according to the internal model simulated outlet coolant temperature of the stack and the outlet temperature of the stack cooling path. The stack inlet coolant target temperature is calculated through a first time domain relationship according to the stack outlet coolant target temperature and the first temperature difference. The first time domain relationship expression is: Among them, T st,in_target (s) is the target temperature of the coolant at the stack inlet, T outer is the time constant of the inner model of the outer loop, s is the Laplace transform variable, K outer is the inner model gain of the outer loop, T f,outer is the filter time constant, T st,out_target(s) is the target temperature of the coolant at the stack outlet, E outer(s) a first temperature difference; The internal model simulated stack inlet coolant temperature is obtained, a second temperature difference is calculated based on the internal model simulated stack inlet coolant temperature and the stack cooling path inlet temperature, and the electronic thermostat opening value is calculated based on the second temperature difference and the stack inlet coolant target temperature through a second time domain relationship. The second time domain relationship expression is: Among them, α actuactor(s) is the opening value of the electronic thermostat, T inner is the time constant of the inner loop internal model, s is the Laplace transform variable, K inner is the inner loop internal model gain, T f，inner is the filter time constant, T st,in_target(s) is the target temperature of the coolant at the stack inlet, E inner(s) is the second temperature difference.

5. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: It also includes a small circulation coolant branch, which is composed of an electronic thermostat, a PTC heater, and a three-way valve.

6. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: The step of classifying the outlet temperature of the cooling path of the stack according to the preset optimal operating temperature threshold of the stack to obtain the outlet temperature grade specifically includes: The optimal operating temperature threshold of the battery stack includes a first temperature threshold and a second temperature threshold; The outlet temperature levels include low temperature section, medium temperature section, and high temperature section; When the outlet temperature of the stack cooling path is not greater than the first temperature threshold, outputting the outlet temperature level as a low temperature stage; When the outlet temperature of the stack cooling path is greater than the first temperature threshold and not greater than the second temperature threshold, outputting the outlet temperature level as a medium temperature section; When the outlet temperature of the stack cooling path is greater than the second temperature threshold, the outlet temperature level is output as a high temperature stage.

7. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: The calculation model expression is: Among them, m cl,req is the required coolant flow rate, Q heat is the heat generated by the system, C cl is the specific heat capacity of the coolant, T st,out is the outlet temperature of the stack cooling path, T st,in is the inlet temperature of the stack cooling path, N cell is the number of cells in the battery stack, I st is the working current, F is the Faraday constant, H react is the enthalpy of hydrogen-oxygen reaction, V st is the stack output voltage.

8. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: The determining result obtained by determining according to the target temperature of the coolant at the stack outlet and the temperature at the stack cooling path outlet includes: The judgment result includes the PTC heater being turned on and the PTC heater being turned off; When the outlet temperature of the stack cooling path is not less than the target temperature of the coolant at the stack outlet, outputting the judgment result that the PTC heater is turned off; When the outlet temperature of the stack cooling path is lower than the target temperature of the coolant at the stack outlet, the judgment result is outputted as the PTC heater is turned on.

9. The fuel cell thermal management system for large load change conditions according to claim 1, characterized in that: The step of classifying the electronic centrifugal pump speed data according to the speed classification threshold to obtain the electronic centrifugal pump speed class includes: The electronic centrifugal pump grades include primary and secondary; When the speed data of the electronic centrifugal pump is less than the speed division threshold, the speed level of the electronic centrifugal pump is output as level one; When the speed data of the electronic centrifugal pump is not less than the speed division threshold, the speed level of the electronic centrifugal pump is output as the second level.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the fuel cell thermal management system for large load change conditions as described in any one of claims 1 to 9 is implemented. A storage medium containing computer executable instructions, characterized in that: When the computer executable instructions are executed by a computer processor, they are used to implement the fuel cell thermal management system for large load change conditions as described in any one of claims 1 to 9.

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