CN119581600A

CN119581600A - Fuel cell system and control method thereof

Info

Publication number: CN119581600A
Application number: CN202311118145.7A
Authority: CN
Inventors: 郭晓亮
Original assignee: Weishi Energy Technology Co Ltd
Current assignee: Weishi Energy Technology Co Ltd
Priority date: 2023-08-31
Filing date: 2023-08-31
Publication date: 2025-03-07

Abstract

The present invention discloses a fuel cell system and a control method thereof. The fuel cell system is applied to a vehicle, and includes: a hydrogen supply component, an air supply component, a stack, a water separator and a thermal management component. The hydrogen supply component includes: a hydrogen storage mechanism, a pressure reducing valve, a plate heat exchanger, a proportional regulating valve and an ejector; the air supply component includes: an air filter, an air compressor, an intercooler and an inlet butterfly valve; the plate heat exchanger and the intercooler are arranged in a close relationship, the air flow channel of the intercooler is respectively connected to the air compressor and the inlet butterfly valve, and the coolant flow channel of the intercooler is connected to the low-temperature heat dissipation circuit of the vehicle; the stack is connected to the ejector, the inlet butterfly valve and the outlet butterfly valve; the water separator is respectively connected to the stack, the ejector, the nitrogen exhaust valve and the drain valve; the thermal management component is respectively connected to the coolant inlet and the coolant outlet of the stack, and the thermal management component is used to constitute the high-temperature heat dissipation circuit of the vehicle. The embodiment of the present invention can improve the operating reliability of the fuel cell system in a low-temperature environment.

Description

Fuel cell system and control method thereof

Technical Field

The present invention relates to the field of battery technologies, and in particular, to a fuel cell system and a control method thereof.

Background

The hydrogen fuel cell system is a power generation system which takes a fuel cell as a core and consists of a hydrogen supply system, an air supply system, a thermal management system, an exhaust emission system, a control system and the like. Hydrogen fuel cell vehicles, when operated, require the consumption of hydrogen to react electrochemically with oxygen in the air to supply the vehicle with electrical power.

When the temperature is too low, the catalytic speed of the catalyst in the fuel cell system is low, the reaction efficiency is low, and the conditions of abnormally low voltage of a single cell in a galvanic pile and the like can be generated, so that the starting process of the hydrogen fuel cell system at low temperature, which is simply called a cold starting process, is always one of the limits of the development of the elbow-pulling fuel cell system in a low-temperature area. At present, the fuel cell cooling system only regulates and controls the cooling liquid of the fuel cell, under the cold start condition, the hydrogen entering the fuel cell from the hydrogen storage system is usually low in temperature, and dew is easy to form under the condition of high internal humidity of the fuel cell, so that the galvanic pile is flooded. Therefore, the existing fuel cell system has low operational reliability in a low temperature environment.

Disclosure of Invention

The invention provides a fuel cell system and a control method thereof, which are used for improving the operation reliability of the fuel cell system in a low-temperature environment.

In a first aspect, an embodiment of the present invention provides a fuel cell system applied to a vehicle, the fuel cell system including:

The hydrogen supply part comprises a hydrogen storage mechanism, a pressure reducing valve, a plate heat exchanger, a proportional control valve and an ejector which are connected in sequence;

The air supply component comprises an air filter, an air compressor, an intercooler and an inlet butterfly valve which are sequentially connected, wherein the plate heat exchanger and the intercooler are in fit arrangement, the intercooler comprises an air flow passage and a cooling liquid flow passage which are mutually independent, the air flow passage is respectively connected with the air compressor and the inlet butterfly valve, and the cooling liquid flow passage is connected with a low-temperature heat dissipation loop of the vehicle;

The hydrogen inlet of the electric pile is connected with the ejector, the air inlet of the electric pile is connected with the inlet butterfly valve, and the first reaction outlet of the electric pile is connected with the outlet butterfly valve;

The water separator is respectively connected with a second reaction outlet of the electric pile and the ejector, and is also respectively connected with a nitrogen discharge valve and a drain valve;

And the thermal management component is respectively connected with the cooling liquid inlet and the cooling liquid outlet of the electric pile and used for controlling the temperature of the electric pile, wherein the thermal management component is used for forming a high-temperature heat dissipation loop of the vehicle.

Optionally, a reaction product treatment cavity and a cooling liquid interlayer which are mutually independent are arranged in the water separator;

The reaction product treatment cavity is respectively connected with the second reaction outlet of the electric pile, the ejector, the nitrogen discharge valve and the drain valve, and the cooling liquid interlayer is connected with the thermal management component.

Optionally, the thermal management component comprises an outlet temperature sensor, a bypass valve, a heater, a radiator, a coolant tank, a deionizer, an electromagnetic valve and a water pump;

The bypass valve is respectively connected with a cooling liquid outlet of the electric pile, an inlet of the heater and an inlet of the radiator, the cooling liquid water tank is connected between the outlet of the radiator and the inlet of the electromagnetic valve, the deionizing device is arranged in the cooling liquid water tank, the outlet of the heater is connected with the inlet of the electromagnetic valve, the water pump is connected between the outlet of the electromagnetic valve and the cooling liquid inlet of the electric pile, and the outlet temperature sensor is used for detecting the temperature of cooling liquid flowing out from the cooling liquid outlet of the electric pile;

The inlet of the electromagnetic valve is also connected with the inlet of the cooling liquid interlayer in the water separator, and the outlet of the electromagnetic valve is also connected with the outlet of the cooling liquid interlayer.

In a second aspect, an embodiment of the present invention further provides a control method of a fuel cell system, configured to control the fuel cell system provided in any embodiment of the present invention, where the control method includes:

Acquiring the ambient temperature of the fuel cell system and the temperature of the cooling liquid at the cooling liquid outlet of the electric pile;

determining a starting strategy of the fuel cell system according to the environment temperature and the cooling liquid temperature, wherein the starting strategy comprises the steps of starting the fuel cell system by adopting a preheating auxiliary cold starting strategy when the environment temperature is smaller than a first preset temperature and the cooling liquid temperature is smaller than a second preset temperature;

Wherein the pre-heating assisted cold start strategy comprises:

and starting the heat management component to heat the cooling liquid in the high-temperature heat dissipation loop until the temperature of the cooling liquid reaches the allowable temperature of the operation of the electric pile, and starting the hydrogen supply component, the air supply component and the electric pile, wherein the allowable temperature of the operation of the electric pile is larger than the first preset temperature.

The thermal management component comprises an outlet temperature sensor, a bypass valve, a heater, a radiator, a cooling liquid water tank, a deionizer, an electromagnetic valve and a water pump;

the starting the hydrogen supply part, the air supply part, and the electric pile includes:

Controlling the hydrogen supply part to transmit hydrogen into the hydrogen cavity of the electric pile, and controlling the air supply part to transmit air into the air cavity of the electric pile, so that the pressures in the hydrogen cavity and the air cavity reach the reaction condition;

Controlling the electromagnetic valve to be a preset opening degree, enabling the cooling liquid interlayer in the water separator to circulate cooling liquid at the maximum allowable flow rate, and enabling the cooling liquid in the high-temperature heat dissipation loop to heat the water separator;

the step of carrying out load pulling and temperature rising is carried out, namely the equivalent impedance of the output load of the electric pile is controlled to be gradually raised to target impedance, and meanwhile, part of energy generated by the reaction in the electric pile generates heat through the internal resistance of the electric pile, and the electric pile is heated;

performing a power response step of adjusting an amount of hydrogen transferred to the stack by the hydrogen supply unit and an amount of air transferred to the stack by the air supply unit in accordance with a power demand signal of the vehicle;

When the temperature of the cooling liquid is smaller than a first judging temperature, adjusting the opening of the bypass valve to enable the cooling liquid flowing out of the cooling liquid outlet to flow through the heater to flow to the cooling liquid inlet, and controlling the working state of the heater according to the temperature of the cooling liquid;

And executing a thermal management dynamic adjustment step, namely dynamically adjusting the operation state of the thermal management component according to the temperature of the cooling liquid.

Optionally, determining a start-up strategy of the fuel cell system according to the ambient temperature and the coolant temperature further comprises:

When the ambient temperature is less than the first preset temperature and the cooling liquid temperature is greater than the second preset temperature, starting the fuel cell system by adopting a low-temperature cold start strategy;

Wherein the low temperature cold start strategy comprises:

executing the pressure build-up step;

Executing the anode temperature control step;

executing the pulling load heating step;

performing the power response step;

Performing the small loop thermal management step;

and performing the thermal management dynamics tuning step.

When the ambient temperature is greater than the first preset temperature and the cooling liquid temperature is greater than a third preset temperature, starting the fuel cell system by adopting a normal-temperature starting strategy of a heat engine, wherein the third preset temperature is greater than the second preset temperature;

The normal temperature starting strategy of the heat engine comprises the following steps:

executing the pressure build-up step;

performing the power response step;

and, performing the thermal management dynamics tuning step;

When the ambient temperature is greater than the first preset temperature and the cooling liquid temperature is less than the third preset temperature, starting the fuel cell system by adopting a cold normal temperature starting strategy;

The cold machine normal temperature starting strategy comprises the following steps:

executing the pressure build-up step;

executing the pulling load heating step;

performing the power response step;

and executing the thermal management dynamic adjustment step.

Optionally, the control method of the fuel cell system further comprises determining a shutdown strategy of the fuel cell system according to the ambient temperature and the cooling liquid temperature when a shutdown instruction is received, wherein the method comprises the following steps:

When the ambient temperature is less than the first preset temperature and the cooling liquid temperature is less than the fourth preset temperature, an auxiliary thermal shutdown strategy is adopted to control the shutdown of the fuel cell system;

wherein the auxiliary thermal shutdown strategy comprises:

And heating the cooling liquid in the high-temperature heat dissipation loop by adopting the thermal management component until the temperature of the cooling liquid reaches the fourth preset temperature, and executing:

controlling the hydrogen supply part to transmit hydrogen to the hydrogen cavity of the electric pile, controlling the air supply part to transmit air to the air cavity of the electric pile, starting the drain valve, carrying out intra-cavity moisture purging on the electric pile, and recording purging duration;

Judging whether a first purging stop condition is met;

If yes, executing a valve sealing protection step, namely controlling the hydrogen supply part to stop transmitting hydrogen into the hydrogen cavity, controlling the air supply part to stop transmitting air into the air cavity, closing the outlet butterfly valve, the nitrogen discharge valve and the drain valve, and controlling a water pump in the thermal management part to stop running;

and if not, returning to execute the step of purging the moisture in the cavity.

Optionally, determining a shutdown strategy of the fuel cell system according to the ambient temperature and the cooling liquid temperature, wherein when the ambient temperature is less than the first preset temperature and the cooling liquid temperature is greater than the fourth preset temperature, the shutdown strategy is adopted to control the shutdown of the fuel cell system;

Wherein, the low temperature shutdown strategy includes:

Executing the intra-cavity moisture purging step;

Judging whether the first purging stop condition is met;

If yes, executing the valve sealing protection step;

If not, returning to execute the step of purging the moisture in the cavity;

when the ambient temperature is higher than the first preset temperature, a normal-temperature shutdown strategy is adopted to control the shutdown of the fuel cell system;

wherein, the normal temperature shutdown strategy comprises:

Executing the intra-cavity moisture purging step;

Judging whether a second purging stop condition is met;

If yes, executing the valve sealing protection step;

Optionally, the first purging stop condition comprises that the purging duration reaches a first target time, and the second purging stop condition comprises that the purging duration reaches a second target time, and the first target time is longer than the second target time;

or before the first time of executing the intracavity moisture purging step, recording the temperature of the cooling liquid before the first time of executing the intracavity moisture purging step as an initial temperature;

the first purging stop condition comprises that the difference between the current cooling liquid temperature and the initial temperature reaches a first temperature difference, and the second purging stop condition comprises that the difference between the current cooling liquid temperature and the initial temperature reaches a second temperature difference, and the first temperature difference is larger than the second temperature difference.

In the embodiment of the invention, the plate heat exchanger attached to the intercooler is arranged in the flow path for transmitting the hydrogen to the electric pile, so that the heat conduction between the intercooler and the plate heat exchanger can be utilized, and the waste heat which is originally required to be discharged to the external environment through the whole-vehicle low-temperature heat dissipation loop in the air flow path is used for heating the hydrogen flow path, namely, the high-temperature gas at the outlet of the air compressor is utilized for completing the temperature rise before the hydrogen enters the pile. Then, in the cold start process, the heat of the compressed air can be used as a heat source for heating the hydrogen, so that the temperature of the hydrogen entering the electric pile for reaction is increased, the risk that the first hydrogen fuel cell in the electric pile is flooded due to low hydrogen entering temperature, the voltage of a single cell is abnormally low and the like is effectively reduced, and the operation reliability of the fuel cell system, especially the operation reliability in a low-temperature environment, is ensured.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic view of a fuel cell system according to an embodiment of the present invention;

fig. 2 is a flowchart of a control method of a fuel cell system provided in an embodiment of the present invention;

Fig. 3 is a flowchart of a start-up strategy of a fuel cell system provided in an embodiment of the present invention;

Fig. 4 is a flowchart of a shutdown strategy of a fuel cell system according to an embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

As described in the background art, the existing fuel cell system has low operational reliability in a low temperature environment, and when an automobile loaded with the fuel cell system is exposed to the low temperature environment, the hydrogen circulation of the fuel cell system and the core component of the water separator are directly exposed to the external environment, and heat exchange occurs with the external environment, so that heat dissipation is extremely fast, and cold start takes a long time. And the problem of large voltage fluctuation easily occurs in the system pulling process, and the condition that the voltage of a single cell of the fuel cell system is abnormally low easily occurs, so that the service life of a pile is influenced. At present, the fuel cell cooling system only regulates and controls the cooling liquid of the fuel cell, and does not interfere with hydrogen, so that the hydrogen entering the fuel cell from the hydrogen storage system is usually low in temperature, and dew is easy to form under the condition of high internal humidity of the fuel cell, so that a pile is flooded. And in the idling period of the fuel cell automobile, the fresh hydrogen consumption and the supply amount of the system are smaller, more circulating hydrogen output from the water separator enters the pile to be subjected to internal reference and reaction, so that the temperature of the circulating hydrogen is lower when the automobile is exposed to a low-temperature environment, and the conditions such as flooding of a hydrogen port, reduction of power generation efficiency, unstable temperature control and the like are easily caused in the stage of carrying out power pulling up again on the system. At present, if a high-power electric heater is used, the cooling liquid is heated by consuming the electric energy stored in the system, and the heating function of the fuel cell system is realized by heat conduction between the cooling liquid and the internal structure of the electric pile, so that the electric energy of the system is greatly consumed. And only a low-power heater is used for heating the cooling liquid cavity, so that the temperature rising speed of the system is low, and the effect of a rapid heating system cannot be achieved.

In order to solve the problems, the embodiment of the invention provides a fuel cell system which can be applied to vehicles, such as fuel cell vehicles, and can effectively improve the operation reliability of the fuel cell system in a low-temperature environment by taking a temperature raising measure on a hydrogen loop. Fig. 1 is a schematic structural diagram of a fuel cell system according to an embodiment of the present invention. Referring to fig. 1, the fuel cell system, which is characterized in that it is applied to a vehicle, includes a hydrogen gas supply part, an air supply part, a stack 31, a water separator 41, and a thermal management part.

Specifically, the hydrogen supply means includes a hydrogen storage mechanism 11, a pressure reducing valve 12, a plate heat exchanger 13, a proportional control valve 14, and an ejector 15 (for example, a venturi tube) connected in this order. The air supply means comprises an air filter 21, an air compressor 22, an intercooler 23 and an inlet butterfly valve 24, which are connected in this order. The hydrogen inlet of the electric pile 31 is connected with the ejector 15, the air inlet of the electric pile 31 is connected with the inlet butterfly valve 24, the first reaction outlet of the electric pile 31 is connected with the outlet butterfly valve 25, and the second reaction outlet of the electric pile 31 is connected with the water separator 41. The water separator 41 is also connected to the eductor 15, nitrogen vent valve 42 and drain valve 43. The thermal management components are respectively connected to the coolant inlet and the coolant outlet of the stack 31 for controlling the temperature of the stack 31.

Wherein, the plate heat exchanger 13 and the intercooler 23 are attached, and the intercooler 23 comprises an air flow passage and a cooling liquid flow passage which are mutually independent. The air flow passage is connected with the air compressor 22 and the inlet butterfly valve 24 respectively as a component part of a transmission path of air to the electric pile 31, and the cooling liquid flow passage is connected with a low-temperature heat dissipation circuit of the vehicle. The heat management component is used for forming a high-temperature heat dissipation loop of the vehicle. The low-temperature heat dissipation loop is used for meeting heat dissipation requirements of components such as a driving motor, an intercooler 23 and a power battery pack of the whole vehicle, and a heat dissipation device used for performing heat exchange with cooling liquid in the low-temperature heat dissipation loop is arranged in the low-temperature heat dissipation loop so as to independently realize heat management in the low-temperature heat dissipation loop. The high-temperature heat dissipation circuit is, for example, a heat dissipation circuit for cooling the stack 31 and other components having a relatively high temperature, and a thermal management member for thermally managing the coolant in the high-temperature heat dissipation circuit is provided in the high-temperature heat dissipation circuit. Since the flow channel inside the stack 31 is relatively small, and the stack 31 has a voltage of hundreds of volts, if the heat dissipation circuit contains higher ion concentration or more impurities, there is a risk of short circuit or blockage of the flow channel. Therefore, the low-temperature heat dissipation loop and the high-temperature heat dissipation loop are separated and independently arranged, and the safe operation of the fuel cell system is facilitated.

The air compressor 22 may be a mainstream centrifugal air compressor used in the fuel cell industry, the outlet temperature of the air compressor 22 may be about 220 ℃, and the proper operating temperature of the fuel cell system may be between 70 and 80 ℃. Therefore, after cooling by the intercooler 23, the cooled air is transferred to the inside of the electric pile. In the prior art, the heat of the compressed air is taken as the waste heat of the system, and is directly released through a low-temperature heat dissipation loop, and the heat of the part is not utilized.

In the embodiment of the present invention, by arranging the plate heat exchanger 13 attached to the intercooler 23 in the flow path for transmitting hydrogen to the electric pile 31, the heat conduction between the intercooler 23 and the plate heat exchanger 13 can be utilized, and the waste heat originally required to be discharged to the external environment through the whole vehicle low-temperature heat dissipation loop in the air flow path is used for heating the hydrogen flow path, namely, the high-temperature gas at the outlet of the air compressor 22 is utilized for completing the temperature rise before hydrogen enters the pile. Then, in the cold start process, the heat of the compressed air can be used as a heat source for heating the hydrogen, so that the temperature of the hydrogen entering the electric pile 31 for reaction is raised, thereby effectively reducing the risk of flooding of the first hydrogen fuel cell in the electric pile 31 due to lower hydrogen entering temperature, abnormal low voltage of a single cell and other problems, and ensuring the operation reliability of the fuel cell system, especially the operation reliability in a low-temperature environment.

The above embodiments are given by way of example, but not by way of limitation, of the present invention in which the temperature of the hydrogen gas is raised before it is fed into the stack by the heat of the compressed air. In other embodiments, temperature control at other locations may also be coordinated to achieve more scientific and stable thermal management of the fuel cell system. The specific structure that the fuel cell system may have will be described first, and the operation thereof will be exemplarily described with reference to the specific structure.

With continued reference to FIG. 1, in addition to the embodiments described above, optionally, a separate reaction product treatment chamber and coolant layer may be provided in the water separator 41. Wherein the reaction product treatment chamber is connected to the second reaction outlet of the electric pile 31, the ejector 15, the nitrogen discharge valve 42 and the drain valve 43, respectively. The coolant interlayer is connected to the thermal management unit so that the coolant in the high temperature heat dissipation circuit can flow through the coolant interlayer to heat the water separator 41.

This embodiment is provided by adding a partition for circulating the coolant to the water separator 41. The interlayer can contain cooling liquid for circulation, and the medium such as hydrogen in the water separator 41 can exchange heat with the cooling liquid through the shell structure of the water separator 41, but cannot be in direct contact. During the reaction of the electric pile 31, the water separator 41 is passed through the products after the reaction, and the products after the reaction include water, nitrogen gas which does not participate in the reaction, and hydrogen gas which does not participate in the reaction. Because water exists in the product after the reaction of the galvanic pile 31, a high-humidity environment can be caused, if the system is stopped, the outer wall of the water separator 41 is directly contacted with the low temperature of the external environment, the water separator 41 can be rapidly cooled, condensed water can appear in the inner flow passage of the reaction product treatment cavity of the water separator 41 along with the cooling process, and under the condition of too low temperature, the condensed water can freeze, so that the nitrogen discharge valve 42 and the valve of the drain valve 43 are blocked. In this embodiment, by introducing the cooling liquid in the high-temperature heat dissipation circuit into the cooling liquid interlayer of the water separator 41, the residual heat generated in the reaction of the electric pile 31 can heat the water separator 41 through the cooling liquid, which is equivalent to heating the discharged part of the reaction product, and preventing the valve from freezing. And, the hydrogen which does not participate in the reaction is transmitted to the ejector 15 through the upper part of the water separator 41 as circulating hydrogen, and then enters the electric pile 31 again for reaction. By heating the water separator 41, the temperature of the circulating hydrogen gas can also be raised, avoiding too low a temperature of the hydrogen gas entering the stack via the water separator 41. Particularly, during the idling of the vehicle at low temperature, under the condition that more circulating hydrogen enters the electric pile 31 to participate in reaction, by heating the water separator 41, the occurrence of condensed water caused by the fact that the circulating hydrogen with lower temperature enters the high-temperature and high-humidity environment in the electric pile 31 can be avoided, and the problems of flooding of a hydrogen port and the like can be effectively avoided. The embodiment is arranged in such a way that the temperature of the water separator 41 can be effectively kept when the vehicle runs at low temperature, and the system can be quickly heated under the condition of starting after stopping.

Specifically, referring to FIG. 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. The bypass valve 52 is connected to the cooling liquid outlet of the stack 31, the inlet of the heater 53 and the inlet of the radiator 54, respectively, the cooling liquid tank 55 is connected between the outlet of the radiator 54 and the inlet of the solenoid valve 57, the deionizer 56 is provided in the cooling liquid 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 cooling liquid inlet of the stack 31, and the outlet temperature sensor 51 is used for detecting the temperature of the cooling liquid flowing out from the cooling liquid outlet of the stack 31. The inlet of the solenoid valve 57 is also connected to the inlet of the coolant layer in the water separator 41, and the outlet of the solenoid valve 57 is also connected to the outlet of the coolant layer. Specifically, the circulation circuit of the coolant layer of the water separator 41 is connected in parallel with the solenoid valve 57, and the flow of the coolant flowing through the coolant layer of the water separator 41 can be controlled by opening and closing the solenoid valve 57, specifically, by adjusting the opening of the solenoid valve 57. In the heat management part, a bypass valve 52, a heater 53, an electromagnetic valve 57 and a water pump 58 can form a small circulation loop of cooling liquid (comprising a cooling liquid interlayer of the water separator 41), which is favorable for rapidly heating the cooling liquid when the heat management part is started in a low-temperature environment, and the small circulation loop is combined with a radiator 54 and a cooling liquid water tank 55, so that a large circulation loop of the cooling liquid can be formed, and the dynamic adjustment of the system temperature in the running process of the system is favorable.

The Fuel cell system may further include a Fuel cell controller (Fuel-cell Control Unit, FCU) connected to each controllable component in the system, for controlling the operation states of each component, for example, controlling the opening degrees of various valves, the operation powers of the air compressor 22, the heater 53, the radiator 54, the water pump 58, and the like, and controlling the reaction process of the electric pile 31.

The functions of the respective components in the fuel cell system will be specifically described with reference to fig. 1.

The hydrogen storage mechanism 11 may be a separate hydrogen storage tank or a liquid hydrogen storage system for storing hydrogen gas. During operation of the vehicle, the hydrogen storage mechanism 11 supplies hydrogen to the fuel cell system through the hydrogen inlet according to the FCU demand.

The air filter 21 is an intake air filter that functions to filter air entering the fuel cell system from the external environment, ensuring that the air entering the system meets the cleanliness requirements of the system for reactant air.

For example, a temperature and flow sensor 26 may be disposed in the flow path between the air filter 21 and the air compressor 22, and configured to measure and obtain signals of the temperature, pressure and flow of the air in the air filter, and transmit the signals to the FCU.

The air compressor 22 is used for boosting air and increasing air flow rate so as to ensure that enough air can participate in the reaction in the electric pile 31 and maintain the efficient operation of the fuel cell system. The air compressor 22 is, for example, a centrifugal air compressor, and the temperature of the air at the outlet of the air compressor can reach about 220 ℃.

The intercooler 23 is provided with mutually independent flow passages for allowing independent flow of air and cooling liquid, and the plate heat exchanger 13 is provided with a flow passage for allowing flow of hydrogen. Heat transfer is performed between the intercooler 23 and the plate heat exchanger 13 through the metal runner partition walls. The cooling liquid in the intercooler is derived from a cooling liquid circulation framework of the whole vehicle, and particularly derived from a low-temperature heat dissipation loop. The low-temperature heat dissipation loop and the high-temperature cooling structure to which the cooling liquid in the electric pile 31 belongs are mutually independent, and the temperature and the flow of the cooling liquid in the low-temperature structure can be controlled by the FCU. Therefore, the cooling function of the high-temperature gas at the outlet of the air compressor 22 can be realized through the cooling liquid from the low-temperature framework of the whole vehicle, and the heating of the compressed air to the hydrogen is completed through the heat transfer between the intercooler 23 and the plate heat exchanger 13. ,

The inlet butterfly valve 24 is an electromagnetic control butterfly valve, can adjust the opening of the valve according to the requirement, and can realize the full-open or full-close function.

The outlet butterfly valve 25 is an electromagnetic control proportional switch valve, the opening degree of the valve can be adjusted according to the requirement, and the limit can realize the full-open or full-close function.

The outlet butterfly valve 25 may be connected to a tail assembly, which is an assembly that collects the product medium after the reaction of the hydrogen fuel cell system and discharges it out of the system.

The stack 31 is the core of the fuel cell system, and is the site for electric energy generation. The stack 31 is formed by stacking a plurality of hydrogen fuel cells. The inside of the stack 31 may be specifically divided into an air chamber, a hydrogen chamber, and a cooling chamber. The hydrogen in the hydrogen chamber reacts electrochemically with the oxygen in the air chamber to produce water inside the stack. The first reaction outlet of the electric pile 31 can be a cathode outlet thereof and is connected with the tail assembly through an outlet butterfly valve 25, and the second reaction outlet of the electric pile 31 can be an anode outlet thereof and is connected with the tail assembly through a water separator 41.

The outlet temperature sensor 51 is a sensor capable of measuring a temperature signal at the coolant outlet of the stack 31, and may transmit the signal to the FCU.

The bypass valve 52 is used for adjusting the opening and closing or opening of the circuit, and the bypass operation of the cooling liquid flowing through the component is completed.

The heater 53 is used to convert electric energy into heat. The heater 53 performs a heating function for the coolant flowing through the inside of the component by consuming electric power.

The solenoid valve 57 is an electromagnetically controlled valve, and can adjust the opening of the valve according to the need to control the split flow.

The water pump 58 is used to drive the flow of coolant and is operated to generate a small amount of heat but insufficient to cause a change in the overall system temperature.

A heat dissipation fan 541 may be installed in the heat sink 54, and the heat sink body and the heat dissipation fan 541 cooperate to dissipate heat inside the system to the external environment, so as to transfer heat generated inside the stack 31.

The coolant tank 55 is, for example, a water overflow kettle, and is placed at the highest point of the system, so as to ensure that a proper liquid amount exists in the high-temperature heat dissipation loop, and at the same time, air bubbles in the cooling pipeline are received, and when the pressure in the tank reaches a threshold value, the air can be exhausted to the outside.

The deionizer 56 is internally provided with a core of anion and cation exchange resin for reducing the electrical conductivity in the high temperature heat dissipation loop so that the system maintains a safe insulation resistance.

In the fuel cell system, the FCU forms a control component in the fuel cell system and is a control unit for the operation of an internal control system of the whole vehicle. The FCU may operate according to a predetermined program within the control system according to a predetermined policy. The stack 31 constitutes a stack assembly and is the main component of the electrochemical reaction in the system. The hydrogen supply part, the water separator 41, the nitrogen discharge valve 42 and the drain valve 43 are combined with the electric pile 31 to form a hydrogen assembly for completing the transmission process of the hydrogen gas path. The air supply and outlet butterfly valves 25, in combination with the stack 31, constitute an air assembly for completing the transfer process of the air path. The thermal management component combines the water separator 41 and the electric pile 31 to form a thermal management component for realizing thermal management of the fuel cell system, and belongs to a component part of a high-temperature heat dissipation loop.

The functions of the components in the fuel cell system, and the constitution of the air module, the hydrogen module, and the thermal management module are described in the above embodiments, and the operation of the components is exemplified below.

For the air component, 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, and the air enters the inside of the electric pile 31 through the inlet butterfly valve 24 after passing through the intercooler 23 so as to react with oxygen and hydrogen in the air. The product discharged from the first reaction outlet of the stack 31 includes nitrogen, residual oxygen and reaction product water which are not involved in the reaction, and the above-mentioned products are discharged together at the tail through the outlet butterfly valve 25, wherein the outlet butterfly valve 25 can implement pressure regulation of the interior of the stack 31 by regulating the opening degree.

For the hydrogen component, hydrogen comes out of the hydrogen storage mechanism 11, passes through the pressure reducing valve 12, exchanges heat with compressed air in the plate heat exchanger 13, and then enters the electric pile 31 through the hydrogen proportional valve 14 and the ejector 15. The hydrogen completes the reaction in the electric pile 31, the products discharged from the second reaction outlet of the electric pile 31 comprise nitrogen and water, and the hydrogen which does not participate in the reaction are separated in the water separator 41, the liquid water is discharged through the water discharge valve 43, and the nitrogen is discharged out of the system through the nitrogen discharge valve 42. Wherein the water separator 41 performs separation by means of different densities of the media. The hydrogen gas has lower density than nitrogen gas and water can reenter the hydrogen supply cycle at the upper part of the water separator 41, complete mixing with high-speed fresh hydrogen gas in the ejector 15, and reenter the electric pile 31 for reference reaction.

And between the hydrogen component and the air component, the high-temperature gas exchanges heat between fins in the intercooler 23 and cooling liquid in the whole vehicle low-temperature heat dissipation loop, and heat transfer is carried out between the high-temperature gas and fresh hydrogen through the plate heat exchanger 13 synchronously, so that the temperature of the hydrogen is raised. By the arrangement, the compressed air is not directly contacted with the hydrogen, and the temperature is limited by introducing the cooling liquid in the low-temperature heat dissipation loop, so that the condition that the gas temperature is too high to be beneficial to subsequent reaction can be avoided. The flow of coolant in the low temperature radiator circuit may be controlled by the FCU or the vehicle controller (Vehicle control unit, VCU).

For the thermal management assembly, the water pump 58 pushes the cooling liquid to circulate in the system, the system distributes the diversion circulation proportion of the cooling liquid through the bypass valve 52, the cooling liquid of the small circulation loop flows through the heater 53 and returns to the electric pile 31 for circulation through the water pump 58, and the cooling liquid of the large circulation loop flows through the bypass valve 52, and returns to the electric pile 31 for circulation through the water pump 58 after passing through the radiator 54 in addition to the small circulation loop. The coolant flows through the deionizer 56 in the coolant tank 55 to remove ions, and the coolant tank 55 synchronously realizes the functions of exhausting the system and supplementing water for the water pump 58. In this assembly, the coolant circuit of the water separator 41 is connected in parallel with the solenoid valve 57, and the diversion condition can be controlled by opening and closing the solenoid valve 57. Specifically, when the system is operated in a low temperature environment, during the system start-up phase, the system may be heated by the small circulation loop until the temperature of the stack 31 reaches the allowable operating temperature, and then the large circulation may be started. In the course of large circulation, if the system temperature is low, the flow rate of cooling liquid flowing through the heater can be increased, the heat loss caused by external heat radiation can be reduced, and if the system temperature is high, the flow rate of cooling liquid flowing through the radiator can be increased. Thus, the dynamic adjustment of the temperature can be realized to ensure the constant temperature of the reaction process as much as possible. The flow rate control of the coolant can be achieved by controlling the opening degrees of the bypass valve 52 and the solenoid valve 57, and adjusting the power of the water pump 58.

In summary, in the fuel cell system provided by the embodiment of the invention, the air path waste heat is used as a heat source in the cold start process of the system, the high-temperature gas at the outlet of the air compressor is used for completing the temperature rise before hydrogen enters the reactor, and then the electric heater of the cooling path is matched for realizing the temperature rise function of the reactor core of the electric reactor, so that three paths of cooperative cold start of air, hydrogen and heat management in the cold start process are synchronously realized, the cold start time is greatly shortened, and the response speed is improved. The embodiment can solve the problems of large voltage fluctuation and low stack temperature in the low-temperature idling and load pulling process, the plate heat exchanger 13 is arranged, cooling liquid is introduced into the water separator 41 to regulate the temperature of hydrogen involved in the reaction, the plate heat exchanger 13 can ensure the temperature of the hydrogen to be stacked, so that the problems of flooding or single low temperature of a first hydrogen fuel cell of the stack due to low hydrogen inlet temperature are avoided, the water separator 41 maintains the hydrogen circulation temperature, the conditions of single low and voltage fluctuation and the like can be avoided during idling, and the situation of icing failure of the drain valve 43 after shutdown can be avoided. And the cold start strategy and the running state of each component of the system are controlled by the air path sensor, and the flow of the cooling liquid entering the intercooler by the whole vehicle low-temperature framework is fed back and regulated, so that the temperature regulation sensitivity is high.

The embodiment of the invention also provides a control method of the fuel cell system, which is used for controlling the fuel cell system provided by any embodiment of the invention, for example, for making and executing starting, running, shutdown strategies and the like of the fuel cell system under different working conditions so as to ensure the running reliability of the fuel cell system under various working conditions and ensure the stable power supply to the vehicle. For example, the control method may be implemented by an FCU, which may be connected to and deployed by, for example, a VCU in a vehicle. The cooling liquid mentioned in the following embodiments refers to the cooling liquid in the high-temperature heat dissipation circuit, that is, the cooling liquid for exchanging heat with the electric pile.

Fig. 2 is a flowchart of a control method of a fuel cell system according to an embodiment of the present invention. With reference to fig. 1 and 2, the control method includes:

S110, acquiring the ambient temperature of the fuel cell system and the temperature of the cooling liquid at the cooling liquid outlet of the electric pile.

Wherein the ambient temperature may be acquired by an ambient temperature sensor and transmitted to the FCU. For example, the ambient temperature sensor may be configured separately in the fuel cell system, such as the temperature flow sensor 26 disposed near the air filter 21, or the ambient temperature sensor may be used in the vehicle to reduce the system cost. The coolant temperature may be collected by an outlet temperature sensor 51 provided at the coolant outlet of the stack 31 and transmitted to the FCU.

S120, determining a starting strategy of the fuel cell system according to the ambient temperature and the cooling liquid temperature.

The starting conditions can be divided into two types, namely normal temperature starting conditions and low temperature starting conditions according to the level of the ambient temperature, for example, the normal temperature starting conditions are when the ambient temperature is higher than a first preset temperature, the low temperature starting conditions are when the ambient temperature is lower than the first preset temperature, and the first preset temperature is for example, 0 ℃ and can be specifically set according to practical situations. Then, for each condition major, dividing the condition minor according to the temperature of the cooling liquid, and formulating corresponding starting strategies for each condition minor.

For example, the environment temperature is higher than the first preset temperature, and the cooling liquid temperature is higher than the third preset temperature, which is the normal temperature starting condition of the heat engine, and can correspond to the normal temperature starting strategy of the heat engine. The ambient temperature is higher than the first preset temperature, and the cooling liquid temperature is lower than the third preset temperature, which is the normal-temperature starting condition of the cold machine, and can correspond to the normal-temperature starting strategy of the cold machine. The third preset temperature is higher than the second preset temperature, and the third preset temperature is, for example, 40 ℃, and can be specifically set according to practical situations. When the temperature of the cooling liquid is higher than the third preset temperature, the temperature of the cooling liquid can be considered to be above the allowable temperature of the electric pile 31 for electric pile operation, so that the electric pile 31 can be directly started to operate in the normal temperature starting strategy of the heat engine without separately setting a heating stage of the electric pile 31, and part of energy can be used for heating the electric pile 31 in the process of carrying the electric pile 31 in the normal temperature starting strategy of the cooler so as to enable the electric pile 31 to quickly reach the allowable temperature for normal operation and further heat the electric pile 31 to the optimal operation temperature. The allowable temperature for operation of the stack is, for example, 40C, and may be specifically set according to the actual situation of the stack 31.

The environment temperature is lower than the first preset temperature, and the cooling liquid temperature is lower than the second preset temperature, which is the preheating cold start condition, and the preheating auxiliary cold start strategy can be corresponding. The second preset temperature is, for example, -10 ℃, and can be specifically set according to practical situations. Under these conditions, the temperature of the cooling liquid is extremely low due to low ambient temperature, which is a bad starting condition, and there is a great risk that the galvanic pile 31 is directly started. Therefore, the heater 53 may be started first to heat the coolant, and the stack 31 and the water separator 41 may be preheated until the coolant temperature reaches the stack operation allowable temperature, and the stack 31 may be restarted, so as to ensure the start-up safety and reliability.

The environment temperature is lower than the first preset temperature, and the cooling liquid temperature is a low-temperature cold start condition when the cooling liquid temperature is higher than the first preset temperature, and the environment temperature is lower than the first preset temperature, and the cooling liquid temperature is a cold start condition when the cooling liquid temperature is between the second preset temperature and the first preset temperature. The low-temperature cold start strategy can be adopted under both the low-temperature cold start condition and the cold start condition of the cold machine. Specifically, the low-temperature cold start condition may correspond to a condition in which the vehicle is started after a short parking in a low-temperature environment, in which case, since the temperature of the coolant has not dropped to an extremely low temperature, a preheating auxiliary means may not be employed. Under the cold start condition of the cold machine, the temperature of the cooling liquid is not reduced to be extremely low, so that a preheating auxiliary means is not needed.

And S130, when a shutdown instruction is received, determining a shutdown strategy of the fuel cell system according to the ambient temperature and the cooling liquid temperature.

Wherein the shutdown instruction is obtained by the VCU and transmitted to the FCU, for example. The shutdown conditions can be divided into two main types of normal-temperature shutdown conditions and low-temperature shutdown conditions according to the level of the ambient temperature, wherein the division can be based on whether the ambient temperature reaches a first preset temperature or not. Then, for each condition major, dividing the condition minor according to the temperature of the cooling liquid, and formulating a corresponding shutdown strategy for each condition minor.

For example, the environment temperature is normal temperature shutdown condition when being higher than the first preset temperature, and the normal temperature shutdown strategy can be corresponding. The environment temperature is lower than the first preset temperature, and the cooling liquid temperature is higher than the fourth preset temperature, so that the low-temperature shutdown condition of the heat engine can be corresponding to the low-temperature shutdown strategy. The fourth preset temperature is, for example, 10 ℃, and may be specifically set according to practical situations. The environment temperature is lower than the first preset temperature, and the cooling liquid temperature is lower than the fourth preset temperature, which is the low-temperature shutdown condition of the chiller, and the shutdown step is executed after the cooling liquid is heated to avoid the occurrence of faults such as icing of the drain valve 43.

In the embodiment of the invention, the starting strategy and the shutdown strategy of the fuel cell system are determined based on the ambient temperature and the cooling liquid temperature, and the corresponding control process can be executed aiming at the specific operation working condition of the fuel cell, so that the reliability of the fuel cell system under various working conditions is ensured, and the stable power supply to the vehicle is ensured.

The following first describes a start-up strategy of the fuel cell system, and then describes a shutdown strategy.

Fig. 3 is a flowchart of a start-up strategy of a fuel cell system according to an embodiment of the present invention. Referring to fig. 3, the start-up strategy includes:

s21, complete machine state self-checking.

In this step, the vehicle VCU may check the communication quality between all of the various components, such as the sensors and actuators, in the vehicle to determine if each component is damaged. And after the communication state of the whole vehicle is determined to be normal, confirming that the fuel cell system can be started.

S22, if the Ta is more than or equal to 0, executing S23, and if the Ta is more than or equal to 0, executing S26.

Where Ta represents the ambient temperature, here by way of example, the first preset temperature is equal to 0 ℃.

S23, if Tc is more than or equal to 40, executing S24, and executing a normal temperature starting strategy of the heat engine, and if not, executing S25, and executing a normal temperature starting strategy of the cold engine.

Wherein Tc represents the coolant temperature, and wherein, as exemplified herein, the third preset temperature is equal to 40 ℃.

S24, executing a normal-temperature starting strategy of the heat engine.

The strategy is specifically required to perform the pressure build-up step, the power response step and the thermal management dynamic adjustment step.

S25, executing a cold machine normal temperature starting strategy.

The strategy is specifically required to execute the steps of pressure establishment, load pulling and temperature rising, power response and dynamic regulation of thermal management.

S26, if Tc is more than or equal to 0, executing S27, and executing a low-temperature cold start strategy, and if not, executing S28.

S27, executing a low-temperature cold start strategy.

The strategy is specifically required to execute a pressure building step, an anode temperature control step, a load-pulling and temperature-rising step, a power response step, a small-cycle heat management step and a heat management dynamic adjustment step.

S28, judging that Tc is less than or equal to-10? if not, executing S27, and executing the low-temperature cold start strategy.

Here, the second preset temperature is equal to-10 ℃.

S29, executing a preheating auxiliary cold start strategy.

The strategy is specifically required to execute an auxiliary heating step, a pressure building step, an anode temperature control step, a pulling load heating step, a power response step, a small-cycle thermal management step and a thermal management dynamic adjustment step.

The present embodiment gives a start-up strategy of the fuel cell system through S21 to S29. Each step in each policy is specifically described below.

And an auxiliary temperature raising step, namely starting a thermal management component to heat the cooling liquid in the high-temperature heat dissipation loop until the temperature of the cooling liquid reaches the allowable temperature of the operation of the electric pile. When the temperature of the cooling liquid reaches the allowable temperature for operation of the electric pile, corresponding to the start-up condition of the electric pile under the low temperature condition, the hydrogen supply part can be started to supply hydrogen to the electric pile 31, the air supply part can be started to supply air to the electric pile 31, and the electric pile 31 can be started to perform electrochemical reaction. The allowable operating temperature of the pile is 40 ℃ for example, and can be determined according to practical situations.

Specifically, in the auxiliary temperature increasing step, the heater 53 may be controlled to operate at 100% power, the water pump 58 may be controlled to operate at 20% power, the solenoid valve 57 may be controlled to a preset opening degree to allow the coolant in the coolant jacket in the water separator 41 to circulate at the maximum allowable flow rate, and the bypass valve 52 may be controlled to open so that the coolant flowing from the coolant outlet flows entirely through the heater 53 to the coolant inlet, i.e., so that the small circulation is fully opened, thereby completing the coolant circulation. Wherein the preset opening is for example between 20% -50%, for example 30%. Specifically, when the solenoid valve 57 is close to full open, the flow path of the coolant layer of the water separator 41 is nearly short-circuited, and the effect of heating the water separator 41 is not achieved. However, if the solenoid valve 57 is close to being turned off, most of the coolant flows through the water separator 41, and the flow passage aperture of the coolant interlayer of the water separator 41 is small, so that the flow rate of the coolant is too high, thereby affecting the circulation process of the whole loop. The balance takes the above into consideration, and a reasonable opening range of the solenoid valve 57 can be obtained.

And a pressure establishing step of controlling the hydrogen supply part to transmit hydrogen into the hydrogen cavity of the electric pile 31 and controlling the air supply part to transmit air into the air cavity of the electric pile 31 so that the pressures in the hydrogen cavity and the air cavity reach the reaction conditions.

Specifically, in the pressure establishment step, the air compressor 22 is controlled to operate at 30% power, the opening of the inlet butterfly valve 24 is controlled to be 100%, and the opening of the outlet butterfly valve 25 is controlled to be a base opening, for example, 50%, so as to establish pressure. The pressure reducing valve 12 is opened, the opening of the proportional control valve 14 is controlled to be 30%, the nitrogen discharge valve 42 is controlled to be opened in a pulse manner, and the drain valve 43 is closed. For example, in 2S, the build-up of pressure within the combustion system cavity is completed. For the thermal management assembly, the heater 53 and the radiator 54 are closed, the water pump 58 is controlled to operate at 20% of power, and the cooling liquid is controlled to circulate through the bypass valve 52 and a loop where the heater 53 is located, so that the influence of the radiator 54 on the temperature is reduced, the local overheating is avoided, and the uniform temperature rise in the electric pile 31 is ensured.

The anode temperature control step comprises the steps of controlling the electromagnetic valve 57 to be a preset opening degree, enabling the cooling liquid interlayer in the water separator 41 to circulate cooling liquid at the maximum allowable flow rate, enabling the cooling liquid in the high-temperature heat dissipation loop to heat the water separator 41, transferring heat of the electric pile 31 to the water separator 41 provided with the drain valve 43 and the nitrogen discharge valve 42 through the cooling liquid, and avoiding freezing of the anode drain valve 43 and the nitrogen discharge valve 42 or flooding caused by large temperature difference between the water separator 41 and the electric pile. Illustratively, in this step, the stack 31 may be controlled to be unloaded, and the energy (electric energy) generated by the reaction in the stack 31 generates heat through the internal resistance of the stack based on the heat conversion formula of q=i ² RT, and the heat pulling load is performed at I ², so that the stack 31 and the cooling liquid are rapidly warmed up. In the case where the drain valve 43 and the nitrogen discharge valve 42 have been frozen, the setting of this step can quickly ice the drain valve 43 and the nitrogen discharge valve 42 for the subsequent normal operation of the battery system. In the case where the drain valve 43 and the nitrogen discharge valve 42 are not frozen, this step corresponds to a step of redundancy setting, and non-execution may be skipped. In this step, the opening of each valve and the power of each device can be set in the last step, or can be changed according to the actual requirement.

And a pulling load heating step, namely controlling the equivalent impedance of the output load of the electric pile 31 to gradually rise to the target impedance, and simultaneously enabling part of energy generated by the reaction in the electric pile 31 to generate heat through the internal resistance of the electric pile to heat the electric pile 31. In this step, the target impedance is determined based on the power demand of the vehicle operation. Unlike the anode temperature control step, in this step, the electric pile 31 outputs normally outwards, and in the process of pulling up the load according to the requirement, the electric pile 31 does work outwards, and meanwhile, based on the heat conversion formula of q=i ² RT, part of the electric energy is converted into heat to heat the electric pile 31. Specifically, in the load-pulling and temperature-raising step, air and hydrogen are introduced into the electric pile 31 to enable the electric pile 31 to react normally, and the electromagnetic valve 57 can be controlled to be at a preset opening degree to enable the cooling liquid in the cooling liquid interlayer in the water separator 41 to flow through the cooling liquid at the maximum allowable flow rate.

And a power response step of adjusting the amount of hydrogen transmitted to the electric pile by the hydrogen supply part and adjusting the amount of air transmitted to the electric pile by the air supply part according to the power demand signal of the vehicle. At this time, the stack 31 outputs power outward, and the FCU may receive the entire vehicle power demand signal and adjust the operating power of the fuel cell system based thereon. Specifically, in the power response step, the air compressor 22 may be set to operate at a basic power, for example, 30% of the power, and then the operating power of the air compressor 22 is adjusted in real time according to a power demand signal, where the power demand signal includes a system target power value, and the operating power of the air compressor 22 and the system target power value form a positive correlation. In this step, the opening of the inlet butterfly valve 24 may be kept at 100% and the opening of the outlet butterfly valve 25 may be kept at a basic opening, for example, 50%, or the air intake amount may be adjusted by adjusting the opening of the inlet butterfly valve 24. In this step, the pressure reducing valve 12 may be controlled to be opened, the initial opening of the proportional control valve 14 may be controlled to be 30%, and the nitrogen discharge valve 42 and the drain valve 43 may be controlled to be opened based on the calibration data pulse. During operation, the opening of the proportional control valve 14, the pulse frequency of the nitrogen bleed valve 42, and the pulse frequency of the drain valve 43 may be adjusted based on the power demand signal. Wherein the opening of the proportional control valve 14, the pulse frequency of the nitrogen discharge valve 42 and the pulse frequency of the water discharge valve 43 are in positive correlation with the target power value of the system.

And a small-cycle thermal management step of adjusting the opening of the bypass valve 52 when the coolant temperature is less than the first determination temperature, causing the coolant flowing out from the coolant outlet to flow entirely through the heater 53 to the coolant inlet, and controlling the operation state of the heater 53 according to the coolant temperature. The first determination temperature is greater than the stack operation allowable temperature and less than the stack optimum operation temperature, and is, for example, 65 ℃.

Specifically, in the small-cycle thermal management step, the small cycle is controlled to be started, and the loop of the radiator 54 is controlled not to circulate the cooling liquid, so that the temperature of the electric pile 31 can be quickly raised, the heat inside the electric pile is ensured to be uniform, and local overheating is avoided. When the temperature of the cooling liquid is greater than the second determination temperature, the heater 53 may be controlled to be turned off, so that the stack 31 is heated by using heat generated by the reaction, and electric energy waste generated by the operation of the heater 53 is avoided. Wherein the second determination temperature is less than the first determination temperature, and further less than the allowable operating temperature of the stack. The second determination temperature is, for example, 30 ℃.

And a thermal management dynamic adjustment step, namely dynamically adjusting the operation state of the thermal management component according to the temperature of the cooling liquid. Specifically, in the thermal management dynamic adjustment step, the water pump 58 is controlled to be operated at 50% of power initially, the cooling fan 541 of the radiator 54 is controlled to be operated at 30% of power initially, and the opening degree of the bypass valve 52, the power of the water pump 58 and the rotation speed of the cooling fan 541 are dynamically adjusted according to the difference between the cooling liquid temperature and the cooling liquid target temperature. The opening of the bypass valve 52, the power of the water pump 58, and the rotation speed of the cooling fan 541 are dynamically adjusted according to the indication of the stack outlet temperature sensor 51, and are all in positive correlation with the cooling liquid temperature. When the coolant temperature exceeds the coolant target temperature, the opening degree of the bypass valve 52 may be adjusted so that the coolant flowing out of the stack 31 is entirely diverted to the circuit in which the radiator 54 is located through the bypass valve 52.

Fig. 4 is a flowchart of a shutdown strategy of a fuel cell system according to an embodiment of the present invention. The shutdown strategy of the fuel cell system will be described in detail with reference to fig. 4.

Referring to fig. 4, in one embodiment, the shutdown strategy may optionally include:

s31, collecting the state of the whole machine.

For example, information of each sensor is collected, and the communication state of the whole vehicle is confirmed again.

S32, if the Ta is more than or equal to 0, executing S33-S35, executing a normal-temperature shutdown strategy, and if the Ta is more than or equal to 0, executing S36.

The step is equivalent to judging whether the ambient temperature reaches a first preset temperature or not so as to determine whether the system operates in a normal-temperature environment or a low-temperature environment. Here, the first preset temperature is, for example, 0 ℃.

The normal temperature shutdown strategy specifically needs to be executed:

s33, a step of purging moisture in the cavity.

S34, if T0-Tq is more than or equal to 2, executing S35, and if not, returning to executing S33.

Wherein this step corresponds to determining whether the second purge stop condition is satisfied. Specifically, the second purge stop condition includes the difference between the current coolant temperature (i.e., tq) and the initial temperature (i.e., T0) reaching a second temperature difference. The second temperature difference is here exemplified at 2 ℃. The initial temperature T0 is the temperature of the coolant before the first chamber moisture purge step is performed. For example, in the normal temperature shutdown strategy, the shutdown command may be received as a recorded time node, and the temperature of the cooling liquid at this time may be captured as the initial temperature T0.

S35, valve sealing protection step.

In this step, the various valves in the system may be controlled to close to protect the catalyst.

S36, if Tc is more than or equal to 10? if not, executing S41-S45, and executing the auxiliary thermal shutdown strategy.

The step is equivalent to judging whether the temperature of the cooling liquid reaches a fourth preset temperature or not so as to judge whether the temperature is required to be raised first and then the machine is turned off. The fourth preset temperature is greater than the first preset temperature, and may be specifically set according to practical situations, where the fourth preset temperature is 10 ℃ as an example.

The low-temperature shutdown strategy specifically needs to be executed:

S37, purging the moisture in the cavity.

S38, if T0-Tq is more than or equal to 4.

Wherein this step corresponds to determining whether the first purge stop condition is satisfied. In particular herein, the second purge stop condition includes that the difference between the current coolant temperature Tq and the initial temperature T0 reaches the first temperature difference. The first temperature difference value is larger than the second temperature difference value, so that more moisture is purged in a low-temperature state, and the influence of a large amount of icing on the next start is avoided. The first temperature difference is, for example, 4 ℃.

S39, valve sealing protection step.

The auxiliary hot shutdown strategy specifically needs to be executed:

s41, an electric auxiliary heating step.

In this step, the coolant in the high temperature heat dissipation loop may be heated using a thermal management component. Specifically, the control of the heater 53 to operate at 100% power, the control of the water pump 58 to operate at 30% power, the control of the solenoid valve 57 to a preset opening, for example, 30%, to circulate the coolant through the coolant jacket in the water separator 41 at the maximum allowable flow rate, and the control of the opening of the bypass valve 52 to allow the coolant flowing from the coolant outlet to flow entirely through the heater 53 to the coolant inlet, i.e., to control the small circulation to be fully opened, may be included.

S42, if Tc is more than or equal to 10? if not, the process returns to S41.

The step is equivalent to judging whether the temperature of the cooling liquid reaches a fourth preset temperature, namely judging whether the system reaches a shutdown condition in a low-temperature environment. The fourth preset temperature is here exemplified by 10 ℃.

S43, purging the moisture in the cavity.

S44, if T0-Tq is not less than 4.

This step corresponds to the judgment of whether the first purge stop condition is satisfied, and is specifically explained with reference to S38.

S45, valve sealing protection step.

The present embodiment implements the shutdown strategy given for the fuel cell system through S31-S45. Wherein S33, S37 and S43 may be the same intra-cavity moisture purging step, and S35, S39 and S45 may be the same valve-closing protection step.

The step of purging the moisture in the cavity comprises the steps of controlling a hydrogen supply part to transmit hydrogen to a hydrogen cavity of the electric pile 31, controlling an air supply part to transmit air to an air cavity of the electric pile 31, starting a drain valve, purging the moisture in the cavity of the electric pile and recording purging time. For example, the determination of whether the purge stop condition is satisfied may be made in real time. Or whether the purging stop condition is met or not can be judged once every preset time, wherein the preset time can be determined according to actual requirements, and the preset time is 10s.

Specifically, in the intra-cavity moisture purging step, the air compressor 22 is controlled to operate at 30% of power, the inlet butterfly valve 24 is controlled to open at 100%, the outlet butterfly valve 25 is controlled to open at 50%, the pressure reducing valve 12 is opened, the proportional control valve 14 is controlled to open at 50%, the drain valve 43 is fully opened, the nitrogen discharge valve 42, the heater 53 and the radiator fan 541 are closed, the solenoid valve 57 is controlled to 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% of power.

The valve-closing protecting step includes controlling the hydrogen supply means to stop the supply of hydrogen into the hydrogen chamber, controlling the air supply means to stop the supply of air into the air chamber, and closing the outlet butterfly valve 25, the nitrogen discharge valve 42, and the drain valve 43. And in the valve-closing protection step, the air compressor 22 is controlled to be shut down, the opening of the inlet butterfly valve 24 is controlled to be 0, the pressure reducing valve 12 is closed, the opening of the proportional regulating valve 14 is controlled to be 0, the opening of the electromagnetic valve 57 is not regulated, the opening of the bypass valve 52 is not regulated, and the water pump 58 is controlled to stop running.

The above embodiment exemplifies a purge stop condition, i.e., metering the degree of moisture purging in temperature, but is not a limitation of the present invention. In other embodiments, other metering methods may be used to determine purge stop conditions. For example, the extent of purging may be measured over time, with longer times resulting in drier stacks 31 after purging. Specifically, the first purging stop condition can be set to include that the purging duration reaches a first target time, and the second purging stop condition can include that the purging duration reaches a second target time, and the first target time is longer than the second target time. Alternatively, the purge level may be directly measured as the dryness level in the stack 31.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present invention may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present invention are achieved, and the present invention is not limited herein.

The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims

1. A fuel cell system, characterized in that it is applied to a vehicle, and 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 it is used to control the fuel cell system according to any one of claims 1 to 3, the control method comprising:

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 is 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 component comprises: 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 the startup strategy of the fuel cell system is determined according to the ambient temperature and the coolant temperature, and further comprising:

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 the startup strategy of the fuel cell system is determined according to the ambient temperature and the coolant temperature, and further comprising:

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;

Execute the thermal management dynamic adjustment step.

8. The control method of the fuel cell system according to claim 4, further comprising: upon receiving a shutdown instruction, determining a shutdown strategy of the fuel cell system according to the ambient temperature and the coolant temperature, comprising:

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 adopted 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:

Moisture purging step in the cavity: 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 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 the shutdown strategy of the fuel cell system is determined according to the ambient temperature and the coolant temperature, and further comprises: when the ambient temperature is lower than the first preset temperature and the coolant temperature is higher than the fourth preset temperature, a low temperature shutdown strategy is adopted 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 purge step, the method further includes: recording the coolant temperature before the first execution of the cavity moisture purge 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.