Fuel cell system and control method thereof

Abstract

The invention discloses a fuel cell system and a control method thereof. The fuel cell system is applied to a vehicle and comprises a hydrogen supply component, an air supply component, an electric pile, a water segregator and a heat management component. The hydrogen supply component comprises a hydrogen storage mechanism, a pressure reducing valve, a plate heat exchanger, a proportioning valve and an ejector; the air supply component comprises an air filter, an air compressor, an intercooler and an inlet butterfly valve; the plate heat exchanger and the intercooler are arranged in an attached mode, an air flow channel of the intercooler is connected with the air compressor and the inlet butterfly valve, and a cooling liquid flow channel of the intercooler is connected with a low-temperature heat dissipation loop of the vehicle. The electric pile is connected with the ejector, the inlet butterfly valve and the outlet butterfly valve; the water segregator is respectively connected with the electric pile, the ejector, the nitrogen discharge valve and the water discharge valve; the heat management component is connected with a cooling liquid inlet and a cooling liquid outlet of the electric pile respectively, and the heat management component is used for forming a high-temperature heat dissipation loop of the vehicle. According to the embodiment of the invention, the operation reliability of the fuel cell system in a low-temperature environment can be improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a fuel cell system and a control method thereof. Background Art

[0002] A hydrogen fuel cell system is a power generation system with a fuel cell as the core, consisting of a hydrogen supply system, an air supply system, a thermal management system, an exhaust emission system, and a control system. When a hydrogen fuel cell vehicle is running, it needs to consume hydrogen to react electrochemically with oxygen in the air to supply the vehicle's electrical energy consumption.

[0003] When the temperature is too low, the catalytic speed of the catalyst in the fuel cell system is slow, the reaction efficiency is low, and the voltage of the single-chip battery in the stack is abnormally low. Therefore, the startup process of the hydrogen fuel cell system at low temperature, referred to as the cold start process, has always been one of the limitations that hinder the development of fuel cell systems in low-temperature areas. At present, the fuel cell cooling system only regulates the coolant of the fuel cell. Under cold start conditions, the hydrogen entering the fuel cell from the hydrogen storage system is usually at a low temperature. When the humidity inside the fuel cell is high, condensation is easily formed, causing flooding of the stack. Therefore, the operating reliability of the existing fuel cell system in low-temperature environments is low. Summary of the invention

[0004] The present invention provides a fuel cell system and a control method thereof, so as to improve the operation reliability of the fuel cell system in a low temperature environment.

[0005] In a first aspect, an embodiment of the present invention provides a fuel cell system, which is applied to a vehicle, and the fuel cell system includes:

[0006] The hydrogen supply component comprises: a hydrogen storage mechanism, a pressure reducing valve, a plate heat exchanger, a proportional regulating valve and an ejector connected in sequence;

[0007] The air supply component comprises: an air filter, an air compressor, an intercooler and an inlet butterfly valve connected in sequence; wherein the plate heat exchanger and the intercooler are arranged in close contact, the intercooler comprises an air flow channel and a coolant flow channel which are independent of each other, the air flow channel is respectively connected to the air compressor and the inlet butterfly valve, and the coolant flow channel is connected to the low-temperature heat dissipation circuit of the vehicle;

[0008] A fuel cell stack, wherein the hydrogen inlet of the fuel cell stack is connected to the ejector, the air inlet of the fuel cell stack is connected to the inlet butterfly valve, and the first reaction outlet of the fuel cell stack is connected to the outlet butterfly valve;

[0009] A water separator, connected to the second reaction outlet of the stack and the ejector, respectively, and the water separator is also connected to a nitrogen exhaust valve and a water discharge valve, respectively;

[0010] A thermal management component is respectively connected to the coolant inlet and the coolant outlet of the fuel cell stack and is used to control the temperature of the fuel cell stack; wherein the thermal management component is used to constitute a high-temperature heat dissipation circuit of the vehicle.

[0011] Optionally, the water separator is provided with a reaction product processing chamber and a cooling liquid interlayer which are independent of each other;

[0012] The reaction product processing chamber is respectively connected to the second reaction outlet of the stack, the ejector, the nitrogen exhaust valve and the water drain valve; the coolant interlayer is connected to the thermal management component.

[0013] Optionally, the thermal management components include: an outlet temperature sensor, a bypass valve, a heater, a radiator, a coolant tank, a deionizer, a solenoid valve and a water pump;

[0014] The bypass valve is respectively connected to the coolant outlet of the stack, the inlet of the heater and the inlet of the radiator; the coolant water tank is connected between the outlet of the radiator and the inlet of the solenoid valve; the deionizer is arranged in the coolant water tank; the outlet of the heater is connected to the inlet of the solenoid valve; the water pump is connected between the outlet of the solenoid valve and the coolant inlet of the stack; the outlet temperature sensor is used to detect the temperature of the coolant flowing out of the coolant outlet of the stack;

[0015] Wherein, the inlet of the solenoid valve is also connected to the inlet of the coolant interlayer in the water distributor, and the outlet of the solenoid valve is also connected to the outlet of the coolant interlayer.

[0016] In a second aspect, an embodiment of the present invention further provides a control method of a fuel cell system, which is used to control the fuel cell system provided by any embodiment of the present invention, and the control method includes:

[0017] Acquiring the ambient temperature of the fuel cell system and the coolant temperature at the coolant outlet of the fuel cell stack;

[0018] Determining a startup strategy of the fuel cell system according to the ambient temperature and the coolant temperature, comprising: when the ambient temperature is less than a first preset temperature and the coolant temperature is less than a second preset temperature, starting the fuel cell system using a preheating assisted cold start strategy;

[0019] The preheating assisted cold start strategy includes:

[0020] The thermal management component is started to heat the coolant in the high-temperature heat dissipation circuit until the coolant temperature reaches a temperature allowing operation of the fuel cell stack, and the hydrogen supply component, the air supply component and the fuel cell stack are started; the temperature allowing operation of the fuel cell stack is greater than the first preset temperature.

[0021] Optionally, the water separator is provided with a reaction product processing chamber and a coolant interlayer which are independent of each other; the thermal management components include: an outlet temperature sensor, a bypass valve, a heater, a radiator, a coolant water tank, a deionizer, a solenoid valve and a water pump;

[0022] The starting of the hydrogen supply component, the air supply component and the fuel cell stack includes:

[0023] Performing a pressure building step: controlling the hydrogen supply component to transmit hydrogen to the hydrogen cavity of the fuel cell stack, and controlling the air supply component to transmit air to the air cavity of the fuel cell stack, so that the pressures in the hydrogen cavity and the air cavity reach reaction conditions;

[0024] Executing the anode temperature control step: controlling the solenoid valve to a preset opening, so that the coolant interlayer in the water separator flows coolant at a maximum allowable flow rate, so that the coolant in the high-temperature heat dissipation circuit heats the water separator;

[0025] Executing a load-raising and temperature-raising step: controlling the equivalent impedance of the output load of the stack to gradually increase to a target impedance, and at the same time allowing part of the energy generated by the reaction in the stack to generate heat through the internal resistance of the stack to raise the temperature of the stack;

[0026] Performing a power response step: adjusting the amount of hydrogen transmitted by the hydrogen supply component to the fuel cell stack and adjusting the amount of air transmitted by the air supply component to the fuel cell stack according to the power demand signal of the vehicle;

[0027] Execute the small cycle thermal management step: when the coolant temperature is lower than the first judgment temperature, adjust the bypass valve opening so that all the coolant flowing out of the coolant outlet flows through the heater to the coolant inlet, and control the working state of the heater according to the coolant temperature; the first judgment temperature is higher than the stack operation allowable temperature;

[0028] Execute a thermal management dynamic adjustment step: dynamically adjust the operating state of the thermal management component according to the coolant temperature.

[0029] Optionally, determining the startup strategy of the fuel cell system according to the ambient temperature and the coolant temperature further includes:

[0030] When the ambient temperature is lower than the first preset temperature and the coolant temperature is higher than the second preset temperature, starting the fuel cell system using a low temperature cold start strategy;

[0031] Wherein, the low temperature cold start strategy includes:

[0032] executing the pressure building step;

[0033] Executing the anode temperature control step;

[0034] Executing the loading and heating step;

[0035] executing the power response step;

[0036] Executing the small cycle thermal management step;

[0037] And, executing the thermal management dynamic adjustment step.

[0038] Optionally, determining the startup strategy of the fuel cell system according to the ambient temperature and the coolant temperature further includes:

[0039] When the ambient temperature is greater than the first preset temperature and the coolant temperature is greater than a third preset temperature, the fuel cell system is started using a thermal engine normal temperature start strategy; wherein the third preset temperature is greater than the second preset temperature;

[0040] The heat engine normal temperature startup strategy includes:

[0041] executing the pressure building step;

[0042] executing the power response step;

[0043] And, executing the thermal management dynamic adjustment step;

[0044] When the ambient temperature is greater than the first preset temperature and the coolant temperature is less than the third preset temperature, starting the fuel cell system using a cold machine normal temperature start-up strategy;

[0045] The cold machine normal temperature startup strategy includes:

[0046] executing the pressure building step;

[0047] Executing the loading and heating step;

[0048] executing the power response step;

[0049] The thermal management dynamic adjustment step is performed.

[0050] Optionally, the control method of the fuel cell system further includes: upon receiving a shutdown instruction, determining a shutdown strategy of the fuel cell system according to the ambient temperature and the coolant temperature, including:

[0051] When the ambient temperature is lower than the first preset temperature, and the coolant temperature is lower than a fourth preset temperature, an auxiliary heat shutdown strategy is used to control the fuel cell system to shut down;

[0052] Wherein, the auxiliary heat shutdown strategy includes:

[0053] The heat management component is used to heat the coolant in the high-temperature heat dissipation circuit until the coolant temperature reaches the fourth preset temperature, and then:

[0054] In-cavity moisture purging step: controlling the hydrogen supply component to transmit hydrogen to the hydrogen cavity of the fuel cell stack, controlling the air supply component to transmit air to the air cavity of the fuel cell stack, and opening the drain valve to purge the moisture in the cavity of the fuel cell stack and record the purge time;

[0055] Determining whether the first purge stop condition is met;

[0056] If yes, the valve sealing protection step is performed: the hydrogen supply component is controlled to stop transmitting hydrogen into the hydrogen chamber, the air supply component is controlled to stop transmitting air into the air chamber, the outlet butterfly valve, the nitrogen exhaust valve and the drain valve are closed, and the water pump in the thermal management component is controlled to stop running;

[0057] If not, the process returns to the step of purging moisture from the cavity.

[0058] Optionally, determining the shutdown strategy of the fuel cell system according to the ambient temperature and the coolant temperature further includes: when the ambient temperature is lower than the first preset temperature and the coolant temperature is higher than the fourth preset temperature, using a low temperature shutdown strategy to control the fuel cell system to shut down;

[0059] Wherein, the low temperature shutdown strategy includes:

[0060] Executing the step of purging moisture in the cavity;

[0061] Determining whether the first purge stop condition is met;

[0062] If yes, then execute the valve sealing protection step;

[0063] If not, return to the step of purging moisture in the cavity;

[0064] When the ambient temperature is greater than the first preset temperature, a normal temperature shutdown strategy is adopted to control the fuel cell system to shut down;

[0065] The normal temperature shutdown strategy includes:

[0066] Executing the step of purging moisture in the cavity;

[0067] Determining whether the second purge stop condition is met;

[0068] If yes, then execute the valve sealing protection step;

[0069] If not, the process returns to the step of purging moisture from the cavity.

[0070] Optionally, the first purge stop condition includes: the purge duration reaches a first target time; the second purge stop condition includes: the purge duration reaches a second target time; the first target time is greater than the second target time;

[0071] Alternatively, before the first execution of the cavity moisture purging step, the method further includes: recording the coolant temperature before the first execution of the cavity moisture purging step as the initial temperature;

[0072] The first purge stop condition includes: the difference between the current coolant temperature and the initial temperature reaches a first temperature difference; the second purge stop condition includes: the difference between the current coolant temperature and the initial temperature reaches a second temperature difference; the first temperature difference is greater than the second temperature difference.

[0073] In the embodiment of the present invention, by providing a plate heat exchanger that is in contact with the intercooler in the flow path of hydrogen transmission to the stack, the heat conduction between the intercooler and the plate heat exchanger can be utilized to heat the hydrogen flow path using the waste heat in the air flow path that originally needs to be discharged to the external environment through the low-temperature heat dissipation circuit of the whole vehicle, that is, the high-temperature gas at the outlet of the air compressor is used to complete the heating of the hydrogen before entering the stack. Then, during the cold start process, the heat of the compressed air can be used as a heat source for heating the hydrogen, increasing the temperature of the hydrogen entering the stack for reaction, thereby effectively reducing the risk of flooding of the first hydrogen fuel cell in the stack due to low hydrogen inlet temperature, and the risk of abnormally low voltage of the single cell, thereby ensuring the operational reliability of the fuel cell system, especially in low-temperature environments.

[0074] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0076] Figure 1 is a structural schematic diagram of a fuel cell system provided by an embodiment of the present invention;

[0077] Figure 2is a flow chart of a control method of a fuel cell system provided by an embodiment of the present invention;

[0078] Figure 3 is a flow chart of a startup strategy of a fuel cell system provided by an embodiment of the present invention;

[0079] Figure 4 This is a flow chart of a shutdown strategy for a fuel cell system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0080] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0081] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0082] As described in the background technology, the operating reliability of the existing fuel cell system in a low temperature environment is low. When a car equipped with a fuel cell system is exposed to a low temperature environment, the core components of the hydrogen cycle and water distributor of the fuel cell system are directly exposed to the external environment, and heat exchange occurs with the external environment. The heat dissipation is extremely fast, and the cold start takes a long time. In addition, the system is prone to large voltage fluctuations during loading, and the single-chip battery of the fuel cell system is prone to abnormally low voltage, which affects the life of the stack. At present, the fuel cell cooling system only regulates the coolant of the fuel cell, and does not intervene in the hydrogen. The hydrogen entering the fuel cell from the hydrogen storage system is usually at a low temperature. When the humidity inside the fuel cell is high, condensation is easily formed, causing the stack to flood. In addition, during the idling period of the fuel cell vehicle, the system's fresh hydrogen consumption and supply are both small, and more circulating hydrogen output from the water distributor enters the stack to participate in the reaction; if the vehicle is exposed to a low temperature environment at this time, the temperature of the circulating hydrogen is low, and when the system is again in the power pull-up stage, it is easy to have hydrogen port flooding, reduced power generation efficiency, and unstable temperature control. At present, if a high-power electric heater is used to heat the coolant by consuming the electric energy stored in the system, and the heating function of the fuel cell system is realized through heat conduction between the coolant and the internal structure of the fuel cell stack, it will cause a large consumption of the system's electric energy. If only a low-power heater is used to heat the coolant cavity, the system will heat up slowly and cannot achieve the effect of quickly heating the system.

[0083] To solve the above problems, an embodiment of the present invention provides a fuel cell system that can be applied to vehicles, such as fuel cell vehicles; the fuel cell system can effectively improve the operating reliability of the fuel cell system in a low temperature environment by taking measures to increase the temperature of the hydrogen circuit. Figure 1 is a schematic diagram of the structure of a fuel cell system provided by an embodiment of the present invention. Figure 1 The fuel cell system is characterized in that it is applied to a vehicle, and the fuel cell system includes: a hydrogen supply component, an air supply component, a fuel cell stack 31, a water separator 41 and a thermal management component.

[0084] Specifically, the hydrogen supply component includes: a hydrogen storage mechanism 11, a pressure reducing valve 12, a plate heat exchanger 13, a proportional regulating valve 14 and an ejector 15 (for example, a venturi tube) connected in sequence. The air supply component includes: an air filter 21, an air compressor 22, an intercooler 23 and an inlet butterfly valve 24 connected in sequence. The hydrogen inlet of the battery stack 31 is connected to the ejector 15, the air inlet of the battery stack 31 is connected to the inlet butterfly valve 24, the first reaction outlet of the battery stack 31 is connected to the outlet butterfly valve 25, and the second reaction outlet of the battery stack 31 is connected to the water separator 41. The water separator 41 is also connected to the ejector 15, the nitrogen exhaust valve 42 and the drain valve 43. The thermal management component is respectively connected to the coolant inlet and the coolant outlet of the battery stack 31, and is used to control the temperature of the battery stack 31.

[0085] Among them, the plate heat exchanger 13 and the intercooler 23 are arranged in close contact, and the intercooler 23 includes an air flow channel and a coolant flow channel that are independent of each other. The air flow channel is connected to the air compressor 22 and the inlet butterfly valve 24 respectively, as a component of the air transmission path to the battery stack 31; the coolant flow channel is connected to the low-temperature heat dissipation circuit of the vehicle. The thermal management component is used to constitute the high-temperature heat dissipation circuit of the vehicle. Among them, the low-temperature heat dissipation circuit is, for example, a heat dissipation circuit used to meet the heat dissipation requirements of components such as the drive motor, the intercooler 23 and the power battery pack of the whole vehicle in the vehicle; the low-temperature heat dissipation circuit is provided with a heat dissipation device for heat exchange with the coolant in the low-temperature heat dissipation circuit to independently realize the thermal management in the low-temperature heat dissipation circuit. The high-temperature heat dissipation circuit is, for example, a heat dissipation circuit for cooling the battery stack 31 and other components with higher temperatures, and the high-temperature heat dissipation circuit is provided with a thermal management component for thermal management of the coolant in the high-temperature heat dissipation circuit. Since the flow channel inside the battery stack 31 is relatively small, and the battery stack 31 has a voltage of hundreds of volts, if the heat dissipation circuit contains a high ion concentration or more impurities, there will be a risk of short circuit or blockage of the flow channel. Therefore, setting up the low-temperature heat dissipation circuit and the high-temperature heat dissipation circuit separately and independently is beneficial to the safe operation of the fuel cell system.

[0086] The air compressor 22 can be a mainstream centrifugal air compressor used in the fuel cell industry. The outlet temperature of the air compressor 22 can reach about 220°C, while the suitable operating temperature of the fuel cell system is between 70-80°C. Therefore, the air needs to be cooled by the intercooler 23 before it can be transferred to the inside of the fuel cell stack. In the prior art, the heat of the compressed air is directly released as system waste heat through the low-temperature heat dissipation circuit, and this part of the heat is not utilized.

[0087] In the embodiment of the present invention, by providing a plate heat exchanger 13 in contact with the intercooler 23 in the flow path of hydrogen transmission to the stack 31, the heat conduction between the intercooler 23 and the plate heat exchanger 13 can be utilized to heat the hydrogen flow path using the waste heat in the air flow path that originally needs to be discharged to the external environment through the low-temperature heat dissipation circuit of the whole vehicle, that is, the high-temperature gas at the outlet of the air compressor 22 is used to complete the heating of the hydrogen before entering the stack. Then, during the cold start process, the heat of the compressed air can be used as a heat source for heating the hydrogen, thereby increasing the temperature of the hydrogen entering the stack 31 for reaction, thereby effectively reducing the risk of flooding of the first hydrogen fuel cell in the stack 31 due to low hydrogen inlet temperature, and the risk of abnormally low voltage of a single cell, thereby ensuring the operational reliability of the fuel cell system, especially in a low temperature environment.

[0088] The above embodiments exemplarily use the heat of compressed air to increase the temperature of hydrogen before it enters the stack, but this is not intended to limit the present invention. In other embodiments, temperature control at other locations may be used to achieve more scientific and stable thermal management of the fuel cell system. The following first describes the specific structure that the fuel cell system may have, and then describes its operation process in combination with its specific structure.

[0089] Continue to see Figure 1 On the basis of the above embodiments, optionally, a reaction product processing chamber and a coolant interlayer are provided in the water separator 41, which are independent of each other. The reaction product processing chamber is respectively connected to the second reaction outlet of the stack 31, the ejector 15, the nitrogen exhaust valve 42 and the drain valve 43. The coolant interlayer is connected to the thermal management component, so that the coolant in the high-temperature heat dissipation circuit can flow through the coolant interlayer to heat the water separator 41.

[0090] This embodiment is configured as follows, which is equivalent to adding a partition for circulating coolant in the water separator 41. The coolant can circulate in the partition, and the hydrogen and other media in the water separator 41 can exchange heat with the coolant through the shell structure of the water separator 41, but they will not be in direct contact. During the reaction of the battery stack 31, the products after the reaction pass through the water separator 41, and the products after the reaction include water, nitrogen that does not participate in the reaction, and hydrogen that does not participate in the reaction. Since there is water in the products after the reaction of the battery stack 31, a high humidity environment will be caused. If the system is shut down, the outer wall of the water separator 41 will directly contact the low temperature of the external environment, and the water separator 41 will cool down rapidly. Condensed water will appear in the internal flow channel of the reaction product processing chamber of the water separator 41 as the temperature drops. When the temperature is too low, the condensed water will freeze, thereby blocking the valves of the nitrogen exhaust valve 42 and the water drain valve 43. In this embodiment, by introducing the coolant in the high-temperature heat dissipation circuit into the coolant interlayer of the water separator 41, the waste heat generated by the stack 31 in the reaction can be heated by the coolant to the water separator 41; it is equivalent to heating the part of the reaction product discharged to prevent the valve from freezing. In addition, the hydrogen that does not participate in the reaction will be used as circulating hydrogen, transmitted to the ejector 15 through the top of the water separator 41, and then enter the stack 31 again for reaction. By heating the water separator 41, the circulating hydrogen can also be heated to avoid the temperature of the hydrogen entering the stack through the water separator 41 being too low. Especially during the idling period of the vehicle at low temperature, when more circulating hydrogen enters the stack 31 to participate in the reaction, by heating the water separator 41, the circulating hydrogen with a lower temperature can be prevented from entering the high temperature and high humidity environment in the stack 31 and condensing water, effectively avoiding the occurrence of problems such as hydrogen port flooding. This embodiment is set up in this way, which can effectively maintain the temperature of the water separator 41 when the vehicle is running at low temperature, and can also quickly heat up the system under the condition of starting after shutdown.

[0091] For details, see Figure 1, the thermal management components may include: an outlet temperature sensor 51, a bypass valve 52, a heater 53, a radiator 54, a coolant tank 55, a deionizer 56, a solenoid valve 57 and a water pump 58. Among them, the bypass valve 52 is respectively connected to the coolant outlet of the stack 31, the inlet of the heater 53 and the inlet of the radiator 54; the coolant tank 55 is connected between the outlet of the radiator 54 and the inlet of the solenoid valve 57; the deionizer 56 is arranged in the coolant tank 55; the outlet of the heater 53 is connected to the inlet of the solenoid valve 57; the water pump 58 is connected between the outlet of the solenoid valve 57 and the coolant inlet of the stack 31; the outlet temperature sensor 51 is used to detect the temperature of the coolant flowing out of the coolant outlet of the stack 31. The inlet of the solenoid valve 57 is also connected to the inlet of the coolant interlayer in the water distributor 41, and the outlet of the solenoid valve 57 is also connected to the outlet of the coolant interlayer. That is, the cooling liquid interlayer of the water separator 41 is connected in parallel with the electromagnetic valve 57, and the diversion can be controlled by opening and closing the electromagnetic valve 57; specifically, by adjusting the opening of the electromagnetic valve 57, the flow rate of the cooling liquid flowing through the cooling liquid interlayer of the water separator 41 can be adjusted. In the thermal management component, the bypass valve 52, the heater 53, the electromagnetic valve 57 and the water pump 58 can form a small circulation loop of the cooling liquid (including the cooling liquid interlayer of the water separator 41), which is conducive to quickly heating the cooling liquid when starting in a low temperature environment; the small circulation loop is combined with the radiator 54 and the cooling liquid water tank 55 to form a large circulation loop of the cooling liquid, which is conducive to dynamically adjusting the system temperature during system operation.

[0092] The fuel cell system may also include a fuel cell controller (Fuel-cell Control Unit, FCU), which connects the various controllable components in the system and is used to control the operating status of each component, such as controlling the opening of various valves, the operating power of the air compressor 22, heater 53, radiator 54 and water pump 58, as well as controlling the reaction process of the fuel cell stack 31.

[0093] Combine the following Figure 1 , the functions of each component in the fuel cell system are described in detail.

[0094] The hydrogen storage mechanism 11 may be an independent hydrogen storage tank or a liquid hydrogen storage system for storing hydrogen. During vehicle operation, the hydrogen storage mechanism 11 supplies hydrogen to the fuel cell system through the hydrogen inlet according to the needs of the FCU.

[0095] The air filter 21 is an intake air filter, and its function is to filter the air entering the fuel cell system from the external environment to ensure that the air entering the system meets the system's requirements for the cleanliness of the reactant air.

[0096] Exemplarily, a temperature flow sensor 26 may be provided in the flow path between the air filter 21 and the air compressor 22 to measure the temperature, pressure and flow signals of the gas in the air filter and transmit the signals to the FCU.

[0097] The air compressor 22 is used to increase the air pressure and increase the air flow rate to ensure that there is enough air inside the stack 31 to participate in the reaction and maintain the efficient operation of the fuel cell system. The air compressor 22 is, for example, a centrifugal air compressor, and the gas temperature at the air compressor outlet can reach about 220°C.

[0098] The intercooler 23 has built-in independent flow channels that allow air and coolant to flow independently; the plate heat exchanger 13 has built-in flow channels that allow hydrogen to circulate. Heat is conducted between the intercooler 23 and the plate heat exchanger 13 through the metal flow channel partition. Among them, the coolant in the intercooler comes from the coolant circulation architecture of the entire vehicle, specifically from the low-temperature heat dissipation circuit. The low-temperature heat dissipation circuit is independent of the high-temperature cooling architecture to which the coolant in the fuel cell stack 31 belongs, and the temperature and flow of the coolant in the low-temperature architecture can be controlled by the FCU. In this way, the cooling function of the high-temperature gas at the outlet of the air compressor 22 can be achieved by the coolant derived from the low-temperature architecture of the entire vehicle; and the heating of the hydrogen by the compressed air is completed through the heat transfer between the intercooler 23 and the plate heat exchanger 13. ,

[0099] The inlet butterfly valve 24 is an electromagnetically controlled butterfly valve, and the opening of the valve can be adjusted according to demand, and the limit can achieve the function of full opening or full closing.

[0100] The outlet butterfly valve 25 is an electromagnetically controlled proportional switch valve, and the opening of the valve can be adjusted according to demand, and the limit can achieve the function of full opening or full closing.

[0101] The outlet butterfly valve 25 can be connected to a tail discharge assembly, which is a assembly that collects the product medium after the hydrogen fuel cell system reaction and discharges it outside the system.

[0102] The stack 31 is the core of the fuel cell system and is the part where electricity is generated. The stack 31 is composed of multiple hydrogen fuel cells stacked together. The interior of the stack 31 can be specifically divided into an air cavity, a hydrogen cavity and a cooling cavity. The hydrogen in the hydrogen cavity and the oxygen in the air cavity undergo an electrochemical reaction inside the stack to produce water. Among them, the first reaction outlet of the stack 31 can be its cathode outlet, which is connected to the tail exhaust assembly through the outlet butterfly valve 25; the second reaction outlet of the stack 31 can be its anode outlet, which is connected to the tail exhaust assembly through the water separator 41.

[0103] The outlet temperature sensor 51 is a sensor that can measure the temperature signal at the coolant outlet of the fuel cell stack 31 and transmit the signal to the FCU.

[0104] The bypass valve 52 is used to adjust the opening and closing or opening size of the circuit to complete the diversion of the coolant flowing through the component.

[0105] The heater 53 is used to convert electric energy into heat. The heater 53 completes the heating function of the coolant flowing through the component by consuming electric energy.

[0106] The solenoid valve 57 is an electromagnetically controlled valve, and the opening of the valve can be adjusted according to demand to control the diversion situation.

[0107] The water pump 58 is used to drive the coolant to flow, and will generate a small amount of heat during operation, but it is not enough to cause the temperature of the entire system to change.

[0108] A cooling fan 541 may be installed in the radiator 54 . The radiator body and the cooling fan 541 cooperate to dissipate the heat inside the system to the external environment, thereby completing the transfer of heat generated inside the fuel cell stack 31 .

[0109] The coolant tank 55 is, for example, an overflow kettle, which is placed at the highest point of the system to ensure that there is an appropriate amount of liquid in the high-temperature heat dissipation circuit and to receive bubbles in the cooling pipeline. When the pressure in the tank reaches a threshold, it can exhaust gas to the outside.

[0110] The deionizer 56 is internally provided with a core of cation exchange resin, which is used to reduce the conductivity inside the high-temperature heat dissipation loop so that the system maintains a safe insulation resistance value.

[0111] In this fuel cell system, the FCU constitutes the control component of the fuel cell system and is the control unit for the operation of the internal control system of the whole vehicle. The FCU can control the operation of the system according to the established program based on the pre-established strategy. The stack 31 constitutes the stack assembly and is the main component of the electrochemical reaction in the system. The hydrogen supply component, the water separator 41, the nitrogen exhaust valve 42 and the drain valve 43, combined with the stack 31, constitute a hydrogen assembly for completing the transmission process of the hydrogen path. The air supply component and the outlet butterfly valve 25, combined with the stack 31, constitute an air assembly for completing the transmission process of the air path. The thermal management component, combined with the water separator 41 and the stack 31, constitutes a thermal management component for realizing thermal management of the fuel cell system, and is a component of the high-temperature heat dissipation circuit.

[0112] In the above-mentioned embodiments, the functions of the components in the fuel cell system, as well as the structures of the air component, the hydrogen component and the thermal management component are described. The operation process of each component is exemplarily described below.

[0113] For the air component: the fresh air in the external environment enters the air compressor 22 after passing through the air filter 21 and the temperature flow sensor 26. The air compressor 22 pressurizes the air and drives the air system to operate. After the air flows through the intercooler 23, it enters the inside of the stack 31 through the inlet butterfly valve 24 to provide oxygen in the air for the reaction with hydrogen. The products discharged from the first reaction outlet of the stack 31 include nitrogen that does not participate in the reaction, residual oxygen and the reaction product water. The above products are discharged together at the tail discharge through the outlet butterfly valve 25, wherein the outlet butterfly 25 can adjust the pressure inside the stack 31 by adjusting the opening.

[0114] For hydrogen components: hydrogen comes out of the hydrogen storage mechanism 11, passes through the pressure reducing valve 12, and exchanges heat with compressed air in the plate heat exchanger 13, and then enters the fuel cell stack 31 through the hydrogen proportional valve 14 and the ejector 15. Hydrogen completes the reaction in the fuel cell stack 31, and the products discharged from the second reaction outlet of the fuel cell stack 31 include: nitrogen, water, and hydrogen that does not participate in the reaction; the above products are separated in the water separator 41, liquid water is discharged through the drain valve 43, and nitrogen is discharged from the system through the nitrogen exhaust valve 42. Among them, the water separator 41 completes the separation through the different densities of the medium. The density of hydrogen is lower than that of nitrogen, and water will re-enter the hydrogen supply cycle at the upper part of the water separator 41, mix with high-speed fresh hydrogen in the ejector 15, and re-enter the fuel cell stack 31 to participate in the reaction.

[0115] Between the hydrogen component and the air component, the high-temperature gas exchanges heat with the coolant in the low-temperature heat dissipation circuit of the vehicle through the internal fins of the intercooler 23, and simultaneously transfers heat with the fresh hydrogen through the plate heat exchanger 13 to complete the hydrogen heating. This arrangement ensures that the compressed air does not directly contact the hydrogen. By introducing the coolant in the low-temperature heat dissipation circuit to limit the temperature, it can avoid the situation where the gas temperature is too high and is not conducive to subsequent reactions. The flow rate of the coolant in the low-temperature heat dissipation circuit can be controlled by the FCU or the vehicle control unit (VCU).

[0116] For the thermal management component: the water pump 58 pushes the coolant to circulate inside the system, and the system distributes the coolant diversion circulation ratio through the bypass valve 52. The coolant in the small circulation loop flows through the heater 53 and returns to the battery stack 31 through the water pump 58 for circulation; after the coolant in the large circulation flows through the bypass valve 52, in addition to passing through the small circulation loop, it also passes through the radiator 54 and then returns to the battery stack 31 through the water pump 58 for circulation. Among them, the coolant flows through the deionizer 56 in the coolant tank 55 for ion removal, and the synchronous coolant tank 55 realizes the function of exhausting the system and replenishing water for the water pump 58. In this component, the coolant circuit of the water distributor 41 is connected in parallel with the solenoid valve 57, and the diversion situation can be controlled by opening and closing the solenoid valve 57. Specifically, when the system is operating in a low temperature environment, during the system startup phase, the system can be heated through the small circulation loop first, until the temperature of the battery stack 31 reaches the allowable operating temperature, and then the large circulation can be opened. The fuel cell needs to maintain a balanced optimal operating temperature range during the reaction process; during the large cycle, if the system temperature is low, the coolant flow through the heater can be increased to reduce the heat loss caused by external heat dissipation; if the system temperature is high, the coolant flow through the radiator can be increased. In this way, dynamic temperature regulation can be achieved to ensure constant temperature during the reaction process as much as possible. The flow control of the coolant can be achieved by controlling the opening of the bypass valve 52 and the solenoid valve 57, and adjusting the power of the water pump 58.

[0117] In summary, in the fuel cell system provided by the embodiment of the present invention, waste heat from the air circuit is used as the heat source during the cold start of the system, and the high-temperature gas at the outlet of the air compressor is used to complete the heating of the hydrogen before entering the stack, and then the electric heater of the cooling circuit is used to realize the heating function of the stack core, and the three-way coordinated cold start of air, hydrogen and thermal management during the cold start process is simultaneously realized, which greatly shortens the cold start time and improves the response speed. This embodiment can solve the problems of large voltage fluctuations and low single-cell voltage during low-temperature idling and loading: the setting of the plate heat exchanger 13 and the introduction of coolant at the water separator 41 can adjust the temperature of the hydrogen participating in the reaction; the plate heat exchanger 13 can ensure the temperature of the hydrogen entering the stack, thereby avoiding flooding or low single-cell voltage problems due to the low hydrogen inlet temperature of the first hydrogen fuel cell in the stack; and the water separator 41 maintains the hydrogen circulation temperature, which can avoid low single-cell voltage and voltage fluctuations during idling, and can also avoid the icing failure of the drain valve 43 after shutdown. In addition, the air path sensor controls the system's cold start strategy and the operating status of each component, and feedback adjusts the coolant flow entering the intercooler of the vehicle's low-temperature architecture, making the temperature regulation highly sensitive.

[0118] An embodiment of the present invention also provides a control method for a fuel cell system, which is used to control the fuel cell system provided by any embodiment of the present invention, for example, to formulate and execute startup, operation and shutdown strategies of the fuel cell system under different operating conditions, so as to ensure the operating reliability of the fuel cell system under various operating conditions and ensure stable power supply to the vehicle. Exemplarily, the control method can be implemented by an FCU, which can be connected to and deployed by a VCU in a vehicle, for example. It should be noted that the coolant mentioned in the following embodiments refers to the coolant in the high-temperature heat dissipation circuit, that is, the coolant used for heat exchange with the fuel cell stack.

[0119] Figure 2 1 is a flow chart of a control method of a fuel cell system provided by an embodiment of the present invention. Figure 1 and Figure 2 , the control method comprises:

[0120] S110, obtaining the ambient temperature of the fuel cell system and the coolant temperature at the coolant outlet of the fuel cell stack.

[0121] The ambient temperature can be acquired by an ambient temperature sensor and transmitted to the FCU. Exemplarily, the ambient temperature sensor can be separately configured in the fuel cell system, such as a temperature flow sensor 26 arranged near the air filter 21; or the existing ambient temperature sensor in the vehicle can be used to reduce system costs. The coolant temperature can be acquired by an outlet temperature sensor 51 arranged at the coolant outlet of the fuel cell stack 31 and transmitted to the FCU.

[0122] S120: Determine a startup strategy for the fuel cell system according to the ambient temperature and the coolant temperature.

[0123] For example, the start-up conditions can be divided into two categories according to the ambient temperature: normal temperature start-up conditions and low temperature start-up conditions; for example, when the ambient temperature is higher than the first preset temperature, it is a normal temperature start-up condition, and when it is lower than the first preset temperature, it is a low temperature start-up condition; the first preset temperature is, for example, 0°C, which can be set according to actual conditions. Then, for each condition category, the condition subcategory is divided according to the coolant temperature, and a corresponding start-up strategy is formulated for each condition subcategory.

[0124] For example: when the ambient temperature is higher than the first preset temperature and the coolant temperature is higher than the third preset temperature, it is a normal temperature start-up condition for a hot engine, which can correspond to a normal temperature start-up strategy for a hot engine. When the ambient temperature is higher than the first preset temperature and the coolant temperature is lower than the third preset temperature, it is a normal temperature start-up condition for a cold engine, which can correspond to a normal temperature start-up strategy for a cold engine. Among them, the third preset temperature is higher than the second preset temperature, and the third preset temperature is, for example, 40°C, which can be set according to actual conditions. When the coolant temperature is higher than the third preset temperature, it can be considered that the coolant temperature is above the allowable operation temperature of the stack 31, so the stack 31 can be started directly in the normal temperature start-up strategy for a hot engine, without setting a heating stage for the stack 31 separately; and in the normal temperature start-up strategy for a cold engine, part of the energy can be used to heat up the stack 31 itself during the process of loading the stack 31, so that the stack 31 quickly reaches its normal operating allowable temperature, and further heats up to its optimal operating temperature. The allowable operation temperature of the stack is, for example, 40°C, which can be set according to the actual conditions of the stack 31.

[0125] When the ambient temperature is lower than the first preset temperature and the coolant temperature is lower than the second preset temperature, it is a preheating cold start condition, which can correspond to a preheating assisted cold start strategy. Among them, the second preset temperature is, for example, -10°C, which can be set according to actual conditions. Under this condition, due to the low ambient temperature and extremely low coolant temperature, it is a harsh starting condition. If the battery stack 31 is started directly, there is a great risk. Therefore, the heater 53 can be started first to heat the coolant, and the battery stack 31 and the water separator 41 can be preheated until the coolant temperature reaches the temperature allowed for the battery stack to operate, and then the battery stack 31 is started to ensure startup safety and reliability.

[0126] When the ambient temperature is lower than the first preset temperature and the coolant temperature is higher than the first preset temperature, it is a low-temperature cold start condition; when the ambient temperature is lower than the first preset temperature and the coolant temperature is between the second preset temperature and the first preset temperature, it is a cold machine cold start condition. The low-temperature cold start strategy can be used under both the low-temperature cold start condition and the cold machine cold start condition. Specifically, the low-temperature cold start condition may correspond to the condition where the vehicle is started after being parked for a short time in a low-temperature environment. At this time, since the coolant temperature has not dropped to an extremely low level, preheating auxiliary means may not be used. Under the cold machine cold start condition, since the coolant temperature has not dropped to an extremely low level either, preheating auxiliary means may also not be used.

[0127] S130 . When a shutdown instruction is received, a shutdown strategy of the fuel cell system is determined according to the ambient temperature and the coolant temperature.

[0128] The shutdown command is obtained by the VCU and transmitted to the FCU. For example, the shutdown conditions can be divided into two categories: normal temperature shutdown conditions and low temperature shutdown conditions according to the ambient temperature; the basis for division can also be whether the ambient temperature reaches the first preset temperature. Then, for each condition category, the condition is divided into subcategories according to the coolant temperature, and a corresponding shutdown strategy is formulated for each condition subcategory.

[0129] For example: when the ambient temperature is higher than the first preset temperature, it is a normal temperature shutdown condition, which can correspond to the normal temperature shutdown strategy. When the ambient temperature is lower than the first preset temperature and the coolant temperature is higher than the fourth preset temperature, it is a hot machine low temperature shutdown condition, which can correspond to the low temperature shutdown strategy. Among them, the fourth preset temperature is, for example, 10°C, which can be set according to actual conditions. When the ambient temperature is lower than the first preset temperature and the coolant temperature is lower than the fourth preset temperature, it is a cold machine low temperature shutdown condition, which can correspond to the auxiliary heat shutdown strategy, first heating the coolant and then executing the shutdown step to avoid faults such as freezing of the drain valve 43.

[0130] In an embodiment of the present invention, the startup strategy and shutdown strategy of the fuel cell system are determined based on the ambient temperature and the coolant temperature, and the corresponding control process can be executed according to the specific operating conditions of the fuel cell to ensure the reliability of the fuel cell system under various operating conditions and ensure stable power supply to the vehicle.

[0131] The following first describes the startup strategy of the fuel cell system in detail, and then describes the shutdown strategy in detail.

[0132] Figure 3 is a flow chart of a startup strategy of a fuel cell system provided by an embodiment of the present invention. Figure 3 , the startup strategy includes:

[0133] S21, self-check of the whole machine status.

[0134] In this step, the vehicle VCU can check the communication quality between all sensors and actuators in the vehicle to determine whether each component is damaged. After confirming that the vehicle communication status is normal, it is confirmed that the fuel cell system can be started.

[0135] S22. Determine whether Ta≥0? If yes, execute S23; if no, execute S26.

[0136] Wherein, Ta represents the ambient temperature, and illustratively, the first preset temperature is equal to 0°C.

[0137] S23. Determine whether Tc is greater than or equal to 40. If yes, execute S24 to execute the normal temperature start strategy for the hot engine; if no, execute S25 to execute the normal temperature start strategy for the cold engine.

[0138] Wherein, Tc represents the coolant temperature; illustratively, the third preset temperature is equal to 40°C.

[0139] S24, executing the hot engine normal temperature start-up strategy.

[0140] Specifically, the strategy needs to execute: pressure building step, power response step and thermal management dynamic adjustment step.

[0141] S25, executing the cold machine normal temperature startup strategy.

[0142] The strategy specifically needs to execute: pressure building step, load and temperature rising step, power response step and thermal management dynamic adjustment step.

[0143] S26. Determine whether Tc ≥ 0? If yes, execute S27 to execute the low-temperature cold start strategy; if no, execute S28.

[0144] S27, executing the low temperature cold start strategy.

[0145] The strategy specifically needs to execute: pressure building step, anode temperature control step, load temperature rise step, power response step, small cycle thermal management step and thermal management dynamic adjustment step.

[0146] S28. Determine Tc ≤ -10? If yes, execute S29 to execute the preheating assisted cold start strategy; if no, execute S27 to execute the low temperature cold start strategy.

[0147] Exemplarily herein, the second preset temperature is equal to -10°C.

[0148] S29, executing the preheating assisted cold start strategy.

[0149] The strategy specifically needs to execute: auxiliary temperature rise step, pressure building step, anode temperature control step, load temperature rise step, power response step, small cycle thermal management step and thermal management dynamic adjustment step.

[0150] This embodiment provides a startup strategy for the fuel cell system through S21-S29. The following is a detailed description of each step in each strategy.

[0151] Auxiliary heating step: Start the thermal management component to heat the coolant in the high-temperature heat dissipation circuit until the coolant temperature reaches the allowable temperature for the stack operation. When the coolant temperature reaches the allowable temperature for the stack operation, it is equivalent to reaching the stack start-up condition under low temperature conditions. The hydrogen supply component can be started to pass hydrogen into the stack 31, the air supply component can be started to pass air into the stack 31, and the stack 31 can be started for electrochemical reaction. Among them, the allowable temperature for the stack operation is, for example, 40°C, which can be determined according to actual conditions.

[0152] Specifically, in the auxiliary heating step, the heater 53 can be controlled to operate at 100% power, the water pump 58 can be controlled to operate at 20% power, and the solenoid valve 57 can be controlled to a preset opening, so that the coolant interlayer in the water distributor 41 flows the coolant at the maximum allowable flow rate; and the bypass valve 52 opening is controlled so that all the coolant flowing out of the coolant outlet flows through the heater 53 to the coolant inlet, that is, the small cycle is fully opened to complete the coolant circulation. Among them, the preset opening is, for example, between 20%-50%, such as 30%. Specifically, when the solenoid valve 57 is close to being fully opened, the flow channel of the coolant interlayer of the water distributor 41 will be almost short-circuited, and the effect of heating the water distributor 41 cannot be achieved. However, if the solenoid valve 57 is close to being closed, most of the coolant flows through the water distributor 41. Since the flow channel aperture of the coolant interlayer of the water distributor 41 is small, this will cause the coolant flow rate to be too large, thereby affecting the circulation process of the entire circuit. By balancing the above situations, a reasonable opening range of the solenoid valve 57 can be obtained.

[0153] Pressure building step: controlling the hydrogen supply component to transmit hydrogen to the hydrogen cavity of the fuel cell stack 31, and controlling the air supply component to transmit air to the air cavity of the fuel cell stack 31, so that the pressure in the hydrogen cavity and the air cavity reaches the reaction condition.

[0154] Specifically, in the pressure building step, the air compressor 22 is controlled to run at 30% power, the inlet butterfly valve 24 is controlled to open at 100%, and the outlet butterfly valve 25 is controlled to open at a basic opening, such as 50%, so as to build pressure. The pressure reducing valve 12 is opened, the proportional regulating valve 14 is controlled to open at 30%, the nitrogen exhaust valve 42 is controlled to open in a pulse, and the drain valve 43 is closed. For example, within 2S, the pressure in the fuel-electric system cavity is established. For thermal management components: turn off the heater 53 and the radiator 54, and control the water pump 58 to run at 20% power; control the coolant to circulate through the bypass valve 52 and the loop where the heater 53 is located, reduce the influence of the radiator 54 on the temperature, avoid local overheating, and ensure uniform temperature rise inside the fuel cell stack 31.

[0155] Anode temperature control step: Control the solenoid valve 57 to a preset opening, so that the coolant in the water separator 41 flows through the coolant at the maximum allowable flow rate, so that the coolant in the high-temperature heat dissipation circuit heats the water separator 41, and transfers the heat of the battery stack 31 to the water separator 41 equipped with the drain valve 43 and the nitrogen exhaust valve 42 through the coolant, so as to avoid freezing of the anode drain valve 43 and the nitrogen exhaust valve 42, or flooding caused by a large temperature difference between the water separator 41 and the battery stack. Exemplarily, in this step, the battery stack 31 can be controlled to be unloaded, based on Q=I 2 According to the heat conversion formula of RT, the energy (electric energy) generated by the reaction in the battery stack 31 generates heat through the internal resistance of the battery stack, and the heat is 2Perform heat loading to rapidly heat up the battery stack 31 and the coolant. When the drain valve 43 and the nitrogen exhaust valve 42 are already frozen, the setting of this step can quickly defrost the drain valve 43 and the nitrogen exhaust valve 42 to facilitate the normal operation of the subsequent battery system. When the drain valve 43 and the nitrogen exhaust valve 42 are not frozen, this step is equivalent to a redundant setting step and can be skipped. In this step, the opening of each valve and the power of each device can continue the setting of the previous step, or be changed according to actual needs.

[0156] Loading and heating step: Control the equivalent impedance of the output load of the stack 31 to gradually increase to the target impedance, and at the same time make part of the energy generated by the reaction in the stack 31 generate heat through the internal resistance of the stack to heat up the stack 31. In this step, the target impedance is determined based on the power demand of the vehicle operation. Different from the anode temperature control step, in this step, the stack 31 outputs normally to the outside. In the process of pulling the load according to the demand, the stack 31 does work externally, and based on Q=I 2 The heat conversion formula of RT converts part of the electrical energy into heat to heat up the stack 31. Specifically, in the pull-load heating step, air and hydrogen are introduced into the stack 31 to allow the stack 31 to react normally; the solenoid valve 57 can be controlled to a preset opening so that the coolant interlayer in the water distributor 41 flows the coolant at the maximum allowable flow rate.

[0157] Power response step: According to the power demand signal of the vehicle, the amount of hydrogen transmitted by the hydrogen supply component to the stack is adjusted, and the amount of air transmitted by the air supply component to the stack is adjusted. At this time, the stack 31 outputs power to the outside, and the FCU can receive the power demand signal of the whole vehicle and adjust the operating power of the fuel-electric system based on this. Specifically, in the power response step, the air compressor 22 can be set to initially operate at a basic power, such as 30% power, and then the operating power of the air compressor 22 can be adjusted in real time according to the power demand signal; wherein the power demand signal contains the system target power value, and the operating power of the air compressor 22 is positively correlated with the system target power value. In this step, the opening of the inlet butterfly valve 24 can be kept at 100%, and the outlet butterfly valve 25 can be kept at a basic opening, such as 50%; or, the amount of air entering the stack can be adjusted by adjusting the opening of the inlet butterfly valve 24. In this step, the pressure reducing valve 12 can be controlled to open; the initial opening of the proportional regulating valve 14 can be controlled to be 30%; and the nitrogen exhaust valve 42 and the water discharge valve 43 can be controlled to open based on the calibration data pulse. During operation, the opening of the proportional control valve 14, the pulse frequency of the nitrogen exhaust valve 42, and the pulse frequency of the drain valve 43 can be adjusted according to the power demand signal. Among them, the opening of the proportional control valve 14, the pulse frequencies of the nitrogen exhaust valve 42 and the drain valve 43 are all positively correlated with the system target power value.

[0158] Small cycle thermal management step: When the coolant temperature is lower than the first judgment temperature, adjust the opening of the bypass valve 52 so that all the coolant flowing out of the coolant outlet flows through the heater 53 to the coolant inlet, and control the working state of the heater 53 according to the coolant temperature. The first judgment temperature is higher than the allowable temperature of the stack operation and lower than the optimal operating temperature of the stack. For example, the first judgment temperature is 65°C.

[0159] Specifically, in the small-cycle thermal management step, the small cycle is controlled to be turned on, and the radiator 54 circuit is controlled to prevent the coolant from flowing, so that the stack 31 can be heated up quickly, the heat inside the stack can be ensured to be uniform, and local overheating can be avoided. Among them, when the coolant temperature is greater than the second judgment temperature, the heater 53 can be controlled to be turned off, so that the stack 31 can be heated up by the heat generated by the reaction, avoiding the waste of electric energy generated by the operation of the heater 53. Among them, the second judgment temperature is lower than the first judgment temperature, and can further be lower than the allowable operating temperature of the stack. Exemplarily, the second judgment temperature is 30°C.

[0160] Dynamic adjustment step of thermal management: dynamically adjust the operating state of the thermal management component according to the coolant temperature. Specifically, in the dynamic adjustment step of thermal management, the water pump 58 can be controlled to initially operate at 50% power, and the cooling fan 541 of the radiator 54 can be controlled to initially operate at 30% power; and the opening of the bypass valve 52, the power of the water pump 58 and the speed of the cooling fan 541 are dynamically adjusted according to the difference between the coolant temperature and the coolant target temperature. Among them, the coolant target temperature is greater than the first judgment temperature, for example, the optimal operating temperature of the stack, for example, set to 75°C; the opening of the bypass valve 52, the power of the water pump 58, and the speed of the cooling fan 541 are dynamically adjusted according to the indication of the stack outlet temperature sensor 51, and are all positively correlated with the coolant temperature. When the coolant temperature exceeds the coolant target temperature, the opening of the bypass valve 52 can be adjusted so that all the coolant flowing out of the stack 31 is diverted to the circuit where the radiator 54 is located through the bypass valve 52.

[0161] Figure 4 This is a flowchart of a shutdown strategy for a fuel cell system provided by an embodiment of the present invention. Figure 4 , the shutdown strategy of the fuel cell system is described in detail.

[0162] See also Figure 4 In one implementation, optionally, the shutdown strategy includes:

[0163] S31. The whole machine status is collected.

[0164] For example, collecting information from each sensor and reconfirming the communication status of the entire vehicle.

[0165] S32. Determine Ta≥0? If yes, execute S33-S35 and execute the normal temperature shutdown strategy; if no, execute S36.

[0166] This step is equivalent to determining whether the ambient temperature reaches a first preset temperature to determine whether the system is operating in a normal temperature environment or a low temperature environment. Here, the first preset temperature is 0°C.

[0167] The normal temperature shutdown strategy needs to be implemented specifically:

[0168] S33, step of purging moisture from the cavity.

[0169] S34. Determine whether T0-Tq≥2. If yes, execute S35; if no, return to execute S33.

[0170] Among them, this step is equivalent to determining whether the second purge stop condition is met. Specifically here, the second purge stop condition includes: the difference between the current coolant temperature (ie, Tq) and the initial temperature (ie, T0) reaches the second temperature difference. Exemplarily here, the second temperature difference is 2°C. The initial temperature T0 is the coolant temperature before the first execution of the intra-cavity moisture purge step. Exemplarily, in the normal temperature shutdown strategy, the receipt of the shutdown command can be used as the time node for recording, and the coolant temperature at this time can be captured as the initial temperature T0.

[0171] S35, valve sealing protection step.

[0172] In this step, various valves in the system can be controlled to close to protect the catalyst.

[0173] S36. Is Tc ≥ 10? If yes, execute S37-S39 to execute the low temperature shutdown strategy; if no, execute S41-S45 to execute the auxiliary heating shutdown strategy.

[0174] This step is equivalent to determining whether the coolant temperature has reached the fourth preset temperature to determine whether it is necessary to heat up before shutting down. The fourth preset temperature is greater than the first preset temperature and can be set according to actual conditions; for example, the fourth preset temperature is 10°C.

[0175] The low temperature shutdown strategy needs to be implemented specifically:

[0176] S37, step of purging moisture from the cavity.

[0177] S38. Determine whether T0-Tq≥4. If yes, execute S39; if no, return to execute S37.

[0178] Among them, this step is equivalent to determining whether the first purge stop condition is met. Specifically, the second purge stop condition includes: the difference between the current coolant temperature Tq and the initial temperature T0 reaches the first temperature difference. Among them, the first temperature difference is greater than the second temperature difference, so as to purge more water under low temperature conditions to avoid a large amount of ice affecting the next start. Exemplarily, the first temperature difference is 4°C.

[0179] S39, valve sealing protection step.

[0180] The auxiliary heat shutdown strategy needs to be implemented specifically:

[0181] S41, electric auxiliary heating temperature raising step.

[0182] In this step, a thermal management component may be used to heat the coolant in the high-temperature heat dissipation circuit. Specifically, the steps may include: controlling the heater 53 to operate at 100% power, controlling the water pump 58 to operate at 30% power, controlling the solenoid valve 57 to a preset opening, such as 30%, so that the coolant interlayer in the water distributor 41 flows the coolant at the maximum allowable flow rate; and controlling the opening of the bypass valve 52 so that all the coolant flowing out of the coolant outlet flows through the heater 53 to the coolant inlet, that is, controlling the small cycle to be fully open.

[0183] S42. Determine whether Tc ≥ 10. If yes, execute S43; if no, return to execute S41.

[0184] This step is equivalent to determining whether the coolant temperature reaches a fourth preset temperature, that is, determining whether the system reaches a shutdown condition in a low temperature environment. Here, the fourth preset temperature is 10°C.

[0185] S43, step of purging moisture from the cavity.

[0186] S44. Determine whether T0-Tq≥4. If yes, execute S45; if no, return to execute S43.

[0187] This step is equivalent to determining whether the first purge stop condition is met, and details can be found in the explanation of S38.

[0188] S45, valve sealing protection step.

[0189] This embodiment implements a shutdown strategy for the fuel cell system through S31-S45, wherein S33, S37 and S43 may be the same chamber moisture purge step, and S35, S39 and S45 may be the same valve sealing protection step.

[0190] The step of purging water in the cavity includes: controlling the hydrogen supply component to transmit hydrogen to the hydrogen cavity of the battery stack 31, controlling the air supply component to transmit air to the air cavity of the battery stack 31, and opening the drain valve to purge the water in the cavity of the battery stack and record the purge time. Exemplarily, it is possible to judge in real time whether the purge stop condition is met. Alternatively, it is possible to judge whether the purge stop condition is met once every preset time interval; the preset time can be determined according to actual needs, and for example, the preset time is 10s.

[0191] Specifically, in the step of purging moisture in the cavity, the air compressor 22 is controlled to operate at 30% power, the inlet butterfly valve 24 is controlled to open at 100%, and the outlet butterfly valve 25 is controlled to open at 50%; the pressure reducing valve 12 is opened, the proportional regulating valve 14 is controlled to open at 50%, the drain valve 43 is controlled to be fully opened, the nitrogen exhaust valve 42, the heater 53 and the cooling fan 541 are closed, the solenoid valve 57 is controlled to be a preset opening, for example, 30%, the bypass valve 52 is controlled to open at 50%, and the water pump 58 is controlled to operate at 30% power.

[0192] The valve sealing protection step includes: controlling the hydrogen supply component to stop transmitting hydrogen into the hydrogen chamber, controlling the air supply component to stop transmitting air into the air chamber, and closing the outlet butterfly valve 25, the nitrogen exhaust valve 42 and the water discharge valve 43. Also, in the valve sealing protection step, the air compressor 22 is controlled to shut down, the inlet butterfly valve 24 is controlled to open to 0, the pressure reducing valve 12 is closed, and the proportional regulating valve 14 is controlled to open to 0; the solenoid valve 57 is not adjusted; the bypass valve 52 is not adjusted; and the water pump 58 is controlled to stop running.

[0193] The above embodiment exemplifies a purge stop condition, that is, measuring the moisture purge degree by temperature, but it is not intended to be a limitation of the present invention. In other embodiments, other measurement methods may also be used to determine the purge stop condition. For example: the purge degree may be measured by time, and the longer the time, the drier the battery stack 31 after the purge. Specifically, the first purge stop condition may be set to include: the purge duration reaches the first target time; the second purge stop condition includes: the purge duration reaches the second target time; the first target time is greater than the second target time. Alternatively, the purge degree may be directly measured by the degree of dryness in the battery stack 31.

[0194] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0195] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fuel cell system, characterized in that: Applied to a vehicle, the fuel cell system comprises: The hydrogen supply component comprises: a hydrogen storage mechanism, a pressure reducing valve, a plate heat exchanger, a proportional regulating valve and an ejector connected in sequence; The air supply component comprises: an air filter, an air compressor, an intercooler and an inlet butterfly valve connected in sequence; wherein the plate heat exchanger and the intercooler are arranged in close contact, the intercooler comprises an air flow channel and a coolant flow channel which are independent of each other, the air flow channel is respectively connected to the air compressor and the inlet butterfly valve, and the coolant flow channel is connected to the low-temperature heat dissipation circuit of the vehicle; A fuel cell stack, wherein the hydrogen inlet of the fuel cell stack is connected to the ejector, the air inlet of the fuel cell stack is connected to the inlet butterfly valve, and the first reaction outlet of the fuel cell stack is connected to the outlet butterfly valve; A water separator, connected to the second reaction outlet of the stack and the ejector, respectively, and the water separator is also connected to a nitrogen exhaust valve and a water discharge valve, respectively; A thermal management component is respectively connected to the coolant inlet and the coolant outlet of the fuel cell stack and is used to control the temperature of the fuel cell stack; wherein the thermal management component is used to constitute a high-temperature heat dissipation circuit of the vehicle.

2. The fuel cell system according to claim 1, characterized in that: The water separator is provided with a reaction product processing chamber and a cooling liquid interlayer which are independent of each other; The reaction product processing chamber is respectively connected to the second reaction outlet of the stack, the ejector, the nitrogen exhaust valve and the water drain valve; the coolant interlayer is connected to the thermal management component.

3. The fuel cell system according to claim 2, characterized in that: The thermal management components include: an outlet temperature sensor, a bypass valve, a heater, a radiator, a coolant tank, a deionizer, a solenoid valve and a water pump; The bypass valve is respectively connected to the coolant outlet of the stack, the inlet of the heater and the inlet of the radiator; the coolant water tank is connected between the outlet of the radiator and the inlet of the solenoid valve; the deionizer is arranged in the coolant water tank; the outlet of the heater is connected to the inlet of the solenoid valve; the water pump is connected between the outlet of the solenoid valve and the coolant inlet of the stack; the outlet temperature sensor is used to detect the temperature of the coolant flowing out of the coolant outlet of the stack; Wherein, the inlet of the solenoid valve is also connected to the inlet of the coolant interlayer in the water distributor, and the outlet of the solenoid valve is also connected to the outlet of the coolant interlayer.

4. A control method for a fuel cell system, characterized in that: For controlling the fuel cell system according to any one of claims 1 to 3, the control method comprises: Acquiring the ambient temperature of the fuel cell system and the coolant temperature at the coolant outlet of the fuel cell stack; Determining a startup strategy of the fuel cell system according to the ambient temperature and the coolant temperature, comprising: when the ambient temperature is less than a first preset temperature and the coolant temperature is less than a second preset temperature, starting the fuel cell system using a preheating assisted cold start strategy; The preheating assisted cold start strategy includes: The thermal management component is started to heat the coolant in the high-temperature heat dissipation circuit until the coolant temperature reaches a temperature allowing operation of the fuel cell stack, and the hydrogen supply component, the air supply component and the fuel cell stack are started; the temperature allowing operation of the fuel cell stack is greater than the first preset temperature.

5. The control method of the fuel cell system according to claim 4, characterized in that: The water separator is provided with a reaction product processing chamber and a coolant interlayer which are independent of each other; the thermal management components include: an outlet temperature sensor, a bypass valve, a heater, a radiator, a coolant water tank, a deionizer, a solenoid valve and a water pump; The starting of the hydrogen supply component, the air supply component and the fuel cell stack includes: Performing a pressure building step: controlling the hydrogen supply component to transmit hydrogen to the hydrogen cavity of the fuel cell stack, and controlling the air supply component to transmit air to the air cavity of the fuel cell stack, so that the pressures in the hydrogen cavity and the air cavity reach reaction conditions; Executing the anode temperature control step: controlling the solenoid valve to a preset opening, so that the coolant interlayer in the water separator flows coolant at a maximum allowable flow rate, so that the coolant in the high-temperature heat dissipation circuit heats the water separator; Executing a load-raising and temperature-raising step: controlling the equivalent impedance of the output load of the stack to gradually increase to a target impedance, and at the same time allowing part of the energy generated by the reaction in the stack to generate heat through the internal resistance of the stack to raise the temperature of the stack; Performing a power response step: adjusting the amount of hydrogen transmitted by the hydrogen supply component to the fuel cell stack and adjusting the amount of air transmitted by the air supply component to the fuel cell stack according to the power demand signal of the vehicle; Execute the small cycle thermal management step: when the coolant temperature is lower than the first judgment temperature, adjust the bypass valve opening so that all the coolant flowing out of the coolant outlet flows through the heater to the coolant inlet, and control the working state of the heater according to the coolant temperature; the first judgment temperature is higher than the stack operation allowable temperature; Execute a thermal management dynamic adjustment step: dynamically adjust the operating state of the thermal management component according to the coolant temperature.

6. The control method of the fuel cell system according to claim 5, characterized in that: Determining a startup strategy of the fuel cell system according to the ambient temperature and the coolant temperature also includes: When the ambient temperature is lower than the first preset temperature and the coolant temperature is higher than the second preset temperature, starting the fuel cell system using a low temperature cold start strategy; Wherein, the low temperature cold start strategy includes: executing the pressure building step; Executing the anode temperature control step; Executing the loading and heating step; executing the power response step; Executing the small cycle thermal management step; And, executing the thermal management dynamic adjustment step.

7. The control method of the fuel cell system according to claim 5, characterized in that: Determining a startup strategy of the fuel cell system according to the ambient temperature and the coolant temperature also includes: When the ambient temperature is greater than the first preset temperature and the coolant temperature is greater than a third preset temperature, the fuel cell system is started using a thermal engine normal temperature start strategy; wherein the third preset temperature is greater than the second preset temperature; The heat engine normal temperature startup strategy includes: executing the pressure building step; executing the power response step; And, executing the thermal management dynamic adjustment step; When the ambient temperature is greater than the first preset temperature and the coolant temperature is less than the third preset temperature, starting the fuel cell system using a cold machine normal temperature start-up strategy; The cold machine normal temperature startup strategy includes: executing the pressure building step; Executing the loading and heating step; executing the power response step; The thermal management dynamic adjustment step is performed.

8. The control method of the fuel cell system according to claim 4, characterized in that: Also includes: When a shutdown instruction is received, determining a shutdown strategy of the fuel cell system according to the ambient temperature and the coolant temperature includes: When the ambient temperature is lower than the first preset temperature, and the coolant temperature is lower than a fourth preset temperature, an auxiliary heat shutdown strategy is used to control the fuel cell system to shut down; Wherein, the auxiliary heat shutdown strategy includes: The heat management component is used to heat the coolant in the high-temperature heat dissipation circuit until the coolant temperature reaches the fourth preset temperature, and then: In-cavity moisture purging step: controlling the hydrogen supply component to transmit hydrogen to the hydrogen cavity of the fuel cell stack, controlling the air supply component to transmit air to the air cavity of the fuel cell stack, and opening the drain valve to purge the moisture in the cavity of the fuel cell stack and record the purge time; Determining whether the first purge stop condition is met; If yes, the valve sealing protection step is performed: the hydrogen supply component is controlled to stop transmitting hydrogen into the hydrogen chamber, the air supply component is controlled to stop transmitting air into the air chamber, the outlet butterfly valve, the nitrogen exhaust valve and the drain valve are closed, and the water pump in the thermal management component is controlled to stop running; If not, the process returns to the step of purging moisture from the cavity.

9. The control method of the fuel cell system according to claim 8, characterized in that: Determining a shutdown strategy of the fuel cell system according to the ambient temperature and the coolant temperature, further comprising: when the ambient temperature is less than the first preset temperature and the coolant temperature is greater than the fourth preset temperature, using a low temperature shutdown strategy to control the fuel cell system to shut down; Wherein, the low temperature shutdown strategy includes: Executing the step of purging moisture in the cavity; Determining whether the first purge stop condition is met; If yes, then execute the valve sealing protection step; If not, return to the step of purging moisture in the cavity; When the ambient temperature is greater than the first preset temperature, a normal temperature shutdown strategy is adopted to control the fuel cell system to shut down; The normal temperature shutdown strategy includes: Executing the step of purging moisture in the cavity; Determining whether the second purge stop condition is met; If yes, then execute the valve sealing protection step; If not, the process returns to the step of purging moisture from the cavity.

10. The control method of the fuel cell system according to claim 9, characterized in that: The first purge stop condition includes: the purge duration reaches a first target time; the second purge stop condition includes: the purge duration reaches a second target time; the first target time is greater than the second target time; Alternatively, before the first execution of the cavity moisture purging step, the method further includes: recording the coolant temperature before the first execution of the cavity moisture purging step as the initial temperature; The first purge stop condition includes: the difference between the current coolant temperature and the initial temperature reaches a first temperature difference; the second purge stop condition includes: the difference between the current coolant temperature and the initial temperature reaches a second temperature difference; the first temperature difference is greater than the second temperature difference.

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