A fuel cell low-temperature cold start control method and system for a passenger car

Abstract

The present invention provides a fuel cell low-temperature cold start control method and system for a passenger car, belonging to the technical field of start control. According to the comparison result between the coolant temperature value and the preset target temperature value, it is judged whether to perform a cold start; under cold start, the small circulation mode is turned on, and the auxiliary heating device PTC continuously heats the coolant until the coolant temperature value rises to the preset target temperature value, then a hot start is performed; during the process of heating the coolant, the PID position algorithm using the limited weakening integral method is adopted to control the actual power of the fuel cell within the maximum power; the present invention adds the auxiliary heating device PTC, introduces a power control strategy, and through setting the maximum power of the fuel cell, the starting power is controlled in real time, solves the problem that the fuel cell cannot start quickly in an extremely cold environment, ensures that the fuel cell can start normally under the heating state, and at the same time improves the start control strategy to ensure the rapidity and efficiency of the fuel cell during the start process.

Description

Technical Field

[0001] The present invention belongs to the technical field of start control, and particularly relates to a fuel cell low-temperature cold start control method and system for buses. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] As a new energy vehicle, fuel cell buses have won the support of many scholars and enterprises due to their high chemical reaction conversion rate, high specific power, and clean and pollution-free tail emissions, so they have broad market prospects.

[0004] However, the inventor found that the application area of fuel cell buses is relatively wide, and it is inevitable to operate in extremely cold working conditions. When the fuel cell is in a relatively low temperature environment, the water generated at the cathode is likely to freeze into ice below 0°C, blocking the gas flow and thus affecting the operation of the fuel cell stack reaction, resulting in the failure of the fuel cell stack to start at low temperature. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a fuel cell low-temperature cold start control method and system for buses, adding an auxiliary heating device PTC, introducing a power control strategy, and controlling the start power in real time by setting the maximum power of the fuel cell, so as to solve the problem that the fuel cell cannot start quickly in extremely cold environments, ensure that the fuel cell can start normally under heating conditions, and at the same time improve the start control strategy to ensure the rapidity and efficiency of the fuel cell during the start process.

[0006] To achieve the above object, one or more embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the present invention provides a fuel cell low-temperature cold start control method for buses;

[0008] A fuel cell low-temperature cold start control method for buses includes:

[0009] After the fuel cell receives the start signal, it determines whether to perform a cold start according to the comparison result between the coolant temperature value and the preset target temperature value;

[0010] Under cold start, the small circulation mode is enabled, and the auxiliary heating device PTC continuously heats the coolant until the coolant temperature value rises to the preset target temperature value, and then a hot start is performed;

[0011] During the process of heating the coolant, the PID position algorithm using the limited weakening integral method is adopted to control the actual power of the fuel cell within the maximum power.

[0012] Further, after the fuel cell receives the startup signal, it first performs a self-check operation to check whether there is a system fault. If a system fault is detected, it will shut down.

[0013] Further, when the coolant temperature is relatively low, in the small circulation mode, the coolant coming out of the fuel cell stack does not pass through the radiator, but directly returns to the fuel cell stack through the thermostat and the auxiliary heating device PTC.

[0014] Further, the coolant temperature value is the coolant temperature value at the outlet of the fuel cell stack;

[0015] Two temperature sensors are provided at the inlet and outlet of the fuel cell stack in the coolant circuit to monitor the coolant temperature values at the inlet and outlet of the fuel cell stack.

[0016] Further, if the coolant temperature value is lower than the preset target temperature value and there is no system fault, cold start is performed; if the coolant temperature value is higher than the preset target temperature value and there is no system fault, hot startup is performed.

[0017] Further, the thermostat, the coolant water pump and the auxiliary heating device PTC are turned on to continuously heat the coolant.

[0018] Further, the thermostat receives the real-time temperature values transmitted by the two temperature sensors and judges whether to perform small circulation heating;

[0019] The rotational speed of the coolant water pump is determined by the temperature difference between the actual temperature value of the coolant at the outlet of the fuel cell stack and the preset target temperature value.

[0020] Further, in the PID position algorithm of the limited weakening integration method, according to the comparison result between the power value at the previous moment and the set maximum power value, when the power is too high, the calculation of the current power value no longer accumulates the integral term, but only accumulates the negative deviation.

[0021] The second aspect of the present invention provides a low-temperature cold start control system for a fuel cell of a bus.

[0022] A low-temperature cold start control system for a fuel cell of a bus includes a temperature comparison unit and a cold start unit;

[0023] The temperature comparison unit is configured to: after the fuel cell receives the startup signal, judge whether to perform cold start according to the comparison result between the coolant temperature value and the preset target temperature value;

[0024] The cold start unit includes a heating unit and a power control unit;

[0025] The heating unit is configured to: in the cold start mode, the auxiliary heating device PTC continuously heats the coolant until the coolant temperature value rises to the preset target temperature value, and then hot startup is performed;

[0026] The power control unit is configured to: during the process of heating the coolant, adopt the PID position algorithm of the limit-weakening integration method to control the actual power of the fuel cell within the maximum power.

[0027] Furthermore, it further includes a self-check unit, which is used to perform a self-check operation on whether there is a fault in the system after the fuel cell receives the startup signal. If a system fault is detected, the system will shut down.

[0028] The above one or more technical solutions have the following beneficial effects:

[0029] Considering that the fuel cell has a relatively slow startup speed during low-temperature cold startup, an auxiliary heating device is added to the original structure. However, the improvement in the structure has a limited effect on the startup speed. Therefore, a power control strategy is introduced. By setting the maximum power of the fuel cell and using this strategy to control the startup power in real time, the actual power is preferably controlled within the maximum power, which is beneficial to maintaining the fast response of the fuel cell.

[0030] Advantages of additional aspects of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0032] Figure 1 It is a flowchart of the method for the first embodiment.

[0033] Figure 2 It is a circuit diagram of the fuel cell coolant for the first embodiment.

[0034] Figure 3 It is a system structure diagram for the second embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] It should be noted that the following detailed description is exemplary and intended to provide further illustration of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present disclosure belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0037] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0038] Aiming at the problem that the fuel cell cannot be quickly started in extremely cold environments, a vehicle-mounted fuel cell low-temperature cold start control method and system proposed by the present invention. After icing occurs at the cathode of the stack, the auxiliary heating device heats the coolant, so that the stack temperature is maintained above 0 °C, maintaining the normal operation of the fuel cell and achieving a quick cold start of the stack at low temperatures. In addition to necessary heating of the fuel cell coolant circuit, the power control strategy in low-temperature environments is also an important method for achieving a quick cold start.

[0039] Embodiment 1

[0040] This embodiment discloses a fuel cell low-temperature cold start control method for buses;

[0041] As Figure 1 shown, a fuel cell low-temperature cold start control method for buses includes:

[0042] Step 1: After the fuel cell receives the startup signal, it determines whether to perform a cold start according to the comparison result between the coolant temperature value and the preset target temperature value;

[0043] When the vehicle high voltage is ready and there is no fault, the fuel cell enable signal FC_ON is sent to the fuel cell. After receiving the startup signal, the fuel cell enters the self-check mode, and then judges whether there is a fault in the system. If a system fault is detected, the fuel cell enters the shutdown state.

[0044] Two temperature sensors are set at the inlet and outlet of the stack in the coolant circuit to monitor the coolant temperature values at the inlet and outlet of the stack. By judging whether the coolant temperature value at the outlet reaches the preset target temperature value, it is judged whether the fuel cell needs to start the cold start mode.

[0045] When the coolant temperature value at the stack outlet is detected to be lower than the preset target temperature value and there is no system fault, it enters the cold start phase; when the coolant temperature value is higher than the preset target temperature value and there is no system fault, it enters the hot start-up phase.

[0046] The preset target temperature value is usually the temperature threshold for the fuel cell to start up.

[0047] Step 2: In the cold start mode, the auxiliary heating device PTC continuously heats the coolant until the coolant temperature value rises to the preset target temperature value, and then it proceeds to hot start-up; during the process of heating the coolant, the PID position algorithm using the limit-weakening integration method is adopted to control the actual power of the fuel cell within the maximum power.

[0048] As Figure 2 shown, it is judged whether to open the small circulation mode through the thermostat. If in the small circulation, the thermostat, coolant water pump and auxiliary heating device PTC are turned on to continuously heat the coolant, and at the same time, the hydrogen path, air path and water path are opened;

[0049] The small circulation mode means that when the coolant temperature is relatively low, the coolant coming out of the stack does not pass through the radiator and directly returns to the stack through the thermostat and the auxiliary heating device PTC, avoiding the loss brought by the cooling system and being able to quickly heat the stack;

[0050] The water path is the loop of the coolant.

[0051] The thermostat receives the real-time temperature value transmitted by the temperature sensor and then judges whether small circulation is needed. When the fuel cell is in small circulation, the PTC heats the coolant in the small circulation pipeline;

[0052] The rotation speed of the coolant water pump is determined by the temperature difference between the actual temperature value of the coolant at the stack outlet and the preset target temperature value.

[0053] The control switch of the hydrogen path inlet valve is turned on, hydrogen enters the hydrogen pipeline, the intake amount is controlled by the opening of the hydrogen proportion valve, and the hydrogen circulation pump adjusts its rotation speed according to the real-time pressure value of the hydrogen path;

[0054] The throttle opening of the air path is related to the air compressor. The opening size of the throttle and the rotation speed of the air compressor determine the air flow of the air path;

[0055] The auxiliary heating device PTC continuously heats to raise the coolant temperature value to the preset target temperature value.

[0056] When it is detected that the coolant temperature value at the stack outlet reaches the preset target temperature value and at the same time it is determined that the coolant temperature difference between the stack inlet and outlet is within the allowable range, the PTC heating mode is turned off and it enters the hot start-up process.

[0057] During the cold start process, a power control strategy is adopted. As the current increases, the demand for hydrogen and air also increases, which causes the voltage of the fuel cell to drop. Therefore, the fuel cell has a maximum current. When the maximum current is exceeded, the performance of the fuel cell will decay. At this time, the power corresponding to the maximum current is the maximum power value of the stack.

[0058] The power control strategy adopts the PID position algorithm with limited weakening integration method to achieve real-time closed-loop control of power.

[0059] Let the maximum power value of the fuel cell be P max , and the power value of the fuel cell at this moment be P(k) , when calculating P(k) , it is judged whether the power value P(k - 1) at the previous moment is greater than P max ; if it is greater than P max , the accumulation of the integral term is no longer carried out, and only the negative deviation is accumulated; if it is less than or equal to P max , normal PID control is carried out, specifically:

[0060] Calculate the power value P(k - 1) at the k - 1 moment:

[0061] (1)

[0062] According to the comparison result of the power value at the k - 1 moment and the set maximum power value, calculate the power at the k moment respectively:

[0063] If , then:

[0064] (The content here seems incomplete in the original, but translated as is) (2)

[0065] If , then:

[0066] (3)

[0067] Among them, the maximum power value of the fuel cell is P max , P(k) , P(k - 1) are the power values of the fuel cell at the k and k - 1 moments, k p , k i , k d are the proportional, differential, and integral coefficients respectively, I(k) ,I(k - 1) , I(k - 2) are the current values at the kth, (k - 1)th, and (k - 2)th moments.

[0068] This strategy controls the power not to exceed the maximum power, which is achieved by controlling the current value. Using this method can control the actual power to fluctuate around the maximum power, avoid a large overshoot at the maximum power, and is beneficial to the quick response during cold start and the maintenance of the fuel cell life.

[0069] Embodiment 2

[0070] This embodiment discloses a low-temperature cold start control system for a fuel cell of a bus;

[0071] As Figure 2 shown, a low-temperature cold start control system for a fuel cell of a bus includes a temperature comparison unit and a cold start unit;

[0072] The temperature comparison unit is configured to: after the fuel cell receives the startup signal, determine whether to perform cold start according to the comparison result between the coolant temperature value and the preset target temperature value;

[0073] The cold start unit includes a heating unit and a power control unit;

[0074] The heating unit is configured to: in the cold start mode, the auxiliary heating device PTC continuously heats the coolant until the coolant temperature value rises to the preset target temperature value, and then performs a hot startup;

[0075] The power control unit is configured to: during the process of heating the coolant, use the PID position algorithm of the limit-weakening integral method to control the actual power of the fuel cell within the maximum power.

[0076] It further includes a self-check unit, which is used to perform a self-check operation on whether there is a fault in the system after the fuel cell receives the startup signal. If a system fault is detected, the system will shut down.

[0077] Those skilled in the art should understand that the embodiments of the present disclosure can be provided as a method, a system, or a computer program product. Therefore, the present disclosure can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present disclosure can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0078] This disclosure is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the disclosure. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or a device for implementing the functions specified in one or more of the blocks.

[0079] These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device that implements the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or a device for implementing the functions specified in one or more of the blocks.

[0080] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or a device for implementing the functions specified in one or more of the blocks.

[0081] The above are only the preferred embodiments of this disclosure and are not used to limit this disclosure. For those skilled in the art, this disclosure can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this disclosure should be included within the protection scope of this disclosure.

[0082] Although the specific implementation manners of this disclosure have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of this disclosure. Those skilled in the art should understand that based on the technical solutions of this disclosure, various modifications or deformations that do not require creative labor by those skilled in the art are still within the protection scope of this disclosure.

Claims

1. A low-temperature cold start control method for a fuel cell for a bus, characterized in that: include: After receiving the start-up signal, the fuel cell determines whether to perform a cold start based on the comparison result of the coolant temperature value and the preset target temperature value; In cold start mode, the small circulation mode is turned on and the auxiliary heating device PTC continues to heat the coolant until the coolant temperature reaches the preset target temperature, and then a hot start is performed; During the cooling process, the PID position algorithm with limited weakening integral method is used to control the actual power of the fuel cell within the maximum power. Among them, the PID position algorithm of the limit weakening integral method, based on the comparison result of the power value at the previous moment and the set maximum power value, when the power is too high, the calculation of the current power value no longer accumulates the integral term, and only accumulates the negative deviation; Among them, the thermostat receives the real-time temperature value transmitted by the temperature sensor and determines whether to perform small-circulation heating; if it is in the small circulation, the thermostat, coolant water pump and auxiliary heating device PTC are turned on to continuously heat the coolant, and the hydrogen path, air path and water path are opened at the same time; the speed of the coolant water pump is determined by the temperature difference between the actual temperature value of the coolant and the preset target temperature value.

2. A low-temperature cold start control method for a fuel cell for a bus according to claim 1, characterized in that: After receiving the power-on signal, the fuel cell first performs a self-check to see if there is any system fault. If a system fault is detected, the fuel cell shuts down.

3. The low-temperature cold start control method for a fuel cell for a bus according to claim 1, characterized in that: The small circulation mode is that when the coolant temperature is low, the coolant coming out of the fuel cell stack does not pass through the radiator, but directly passes through the thermostat and the auxiliary heating device PTC and returns to the fuel cell stack.

4. The low-temperature cold start control method for a fuel cell for a bus according to claim 1, characterized in that: The coolant temperature value is the coolant temperature value at the stack outlet; Two temperature sensors are set at the inlet and outlet of the coolant loop to monitor the coolant temperature values at the inlet and outlet of the coolant stack.

5. The low-temperature cold start control method for a fuel cell for a bus according to claim 1, characterized in that: If the coolant temperature is lower than the preset target temperature and there is no system fault, a cold start is performed; if the coolant temperature is higher than the preset target temperature and there is no system fault, a hot start is performed.

6. A fuel cell low-temperature cold start control system for a bus, characterized by: Including temperature comparison unit and cold start unit; The temperature comparison unit is configured to: after the fuel cell receives the start-up signal, determine whether to perform a cold start based on a comparison result between the coolant temperature value and a preset target temperature value; A cold start unit, including a heating unit and a power control unit; The heating unit is configured as follows: in cold start mode, the auxiliary heating device PTC continues to heat the coolant until the coolant temperature value rises to a preset target temperature value, and then a hot start is performed; The power control unit is configured to: during the process of heating the coolant, use a PID position algorithm with a limited weakening integral method to control the actual power of the fuel cell within the maximum power; Among them, the PID position algorithm of the limit weakening integral method, based on the comparison result of the power value at the previous moment and the set maximum power value, when the power is too high, the calculation of the current power value no longer accumulates the integral term, and only accumulates the negative deviation; Among them, the thermostat receives the real-time temperature value transmitted by the temperature sensor and determines whether to perform small-circulation heating; if it is in the small circulation, the thermostat, coolant water pump and auxiliary heating device PTC are turned on to continuously heat the coolant, and the hydrogen path, air path and water path are opened at the same time; the speed of the coolant water pump is determined by the temperature difference between the actual temperature value of the coolant and the preset target temperature value.

7. A low-temperature cold start control system for a fuel cell used in a bus as claimed in claim 6, characterized in that: It also includes a self-check unit, which is used to perform a self-check operation on the system to check whether there is any fault after the fuel cell receives the power-on signal. If a system fault is detected, the system will be shut down.

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