Fuel cell system and control method thereof

Abstract

The invention discloses a fuel cell system and a control method thereof. The fuel cell system comprises the following steps: acquiring actual pressure and a pressure safety threshold value of a first end of a primary electric pile; when the actual pressure of the first end of the first-stage electric pile is greater than a pressure safety threshold value, determining a difference value between the actual pressure and the pressure safety threshold value; according to the difference value between the actual pressure and the pressure safety threshold value, the deviation value of the gas fuel in the pipeline is determined; according to the corresponding relation between the temperature and the content of the gas fuel, the temperature difference corresponding to the deviation value of the gas fuel is determined; the actual temperature of the fourth end of the condenser is obtained, and the set temperature needing to be adjusted is determined according to the actual temperature of the fourth end and the temperature difference; and according to the set temperature, the cooling liquid flow adjusted by the cooling water pump is adjusted until the set temperature needing to be adjusted is reached, and it is determined that the actual pressure of the first end of the first-stage galvanic pile is smaller than or equal to the pressure safety threshold value. The pressure of the first-stage electric pile can be prevented from being too high, and it is guaranteed that the first-stage electric pile operates within the safe pressure boundary.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a fuel cell system and a control method thereof. Background Art

[0002] A fuel cell is a chemical device that directly converts the chemical energy of a fuel into electrical energy, also known as an electrochemical generator. Stack series connection is one of the effective methods to improve the fuel utilization rate of a fuel cell system. The improvement of the fuel utilization rate can directly improve the power generation efficiency of the fuel cell system. However, stack series connection will increase the system flow loss. Flow loss refers to the energy loss generated by the gas fuel in the fuel cell system during the flow process due to frictional resistance, etc., mainly manifested as a decrease in pressure (static pressure). Especially in the case where the number of stacks between stages is inconsistent. Since it is considered that the fuel entering the second-stage stack comes from the tail gas after the reaction of the first-stage stack, its fuel concentration decreases relatively. This requires the second-stage stack to exhibit better performance, but this will accelerate the attenuation of the second-stage stack. Therefore, generally, a design with the number of first-stage stacks greater than that of the second-stage stacks is adopted to reduce the risk of system performance attenuation.

[0003] However, for the second-stage stack, the amount of fuel entering is higher than that of the first-stage stack, which will greatly increase the fuel flow loss and ultimately lead to too high an inlet pressure of the first-stage stack or even exceeding the safety boundary. In existing proton exchange membrane fuel cells, it is mainly considered that if the hydrogen flow rate entering the stack is too large instantaneously and the pressure is too high instantaneously, the proton exchange membrane will be punctured. Therefore, a pressure relief safety valve is mostly set to achieve instantaneous pressure relief protection. It does not consider the phenomenon of too high an inlet pressure of the first-stage stack caused by the stack arrangement during the normal operation of the system, and the instantaneous pressure relief method directly discharges the fuel (hydrogen) into the air, which is too dangerous. Summary of the Invention

[0004] The present invention provides a fuel cell system and a control method thereof, which can avoid too high a pressure of the first-stage stack and ensure that the first-stage stack operates within the safe pressure boundary.

[0005] According to one aspect of the present invention, a fuel cell system is provided, including:

[0006] A first-stage stack, a cooling water pump, a condenser, a gas-water separator, a second-stage stack, and a controller;

[0007] The second end of the first-stage stack is connected to the first end of the condenser through a pipeline; the first end of the cooling water pump is connected to the second end of the condenser through a coolant pipeline, the third end of the condenser is connected to the second end of the cooling water pump through a coolant pipeline, the fourth end of the condenser is connected to the first end of the gas-water separator through a pipeline, the second end of the gas-water separator is connected to the first end of the second-stage stack through a pipeline, and the third end of the gas-water separator is also connected to the first end of the first-stage stack through a pipeline;

[0008] The controller is electrically connected to the first-stage stack, the cooling water pump, the condenser, the gas-water separator, and the second-stage stack;

[0009] The controller is used for:

[0010] Obtain the actual pressure at the first end of the first-stage stack and the pressure safety threshold of the first-stage stack;

[0011] When the actual pressure at the first end of the first-stage stack is greater than the pressure safety threshold, determine the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold;

[0012] According to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold, determine the deviation value of the gaseous fuel separated by the gas-water separator in the pipeline;

[0013] According to the corresponding relationship between the temperature and the content of the gaseous fuel, determine the temperature difference corresponding to the deviation value of the gaseous fuel;

[0014] Obtain the actual temperature at the fourth end of the condenser, and according to the actual temperature at the fourth end of the condenser and the temperature difference, determine the set temperature to be adjusted;

[0015] According to the set temperature to be adjusted, adjust the coolant flow rate adjusted by the cooling water pump until the set temperature to be adjusted is reached, and determine that the actual pressure at the first end of the first-stage stack is less than or equal to the pressure safety threshold.

[0016] Optionally, the controller is used to determine the flow rate of the gaseous fuel separated by the gas-water separator in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold; according to the flow rate of the gaseous fuel separated by the gas-water separator, determine the deviation value of the gaseous fuel separated by the gas-water separator in the pipeline.

[0017] Optionally, the controller is further used to determine that the first-stage stack is operating safely when the actual pressure at the first end of the first-stage stack is greater than or equal to the pressure safety threshold.

[0018] Optionally, the fuel cell system further includes:

[0019] The first fuel mixer, the evaporator, the first reformer, the air preheater, the air mixer, the second fuel mixer, the second reformer, and the burner;

[0020] The controller is electrically connected to the first fuel mixer, the evaporator, the first reformer, the air preheater, the air mixer, the second fuel mixer, the second reformer, and the burner;

[0021] The first end of the first fuel mixer is used to receive external fresh fuel. The second end of the first fuel mixer is connected to the first end of the evaporator through a pipeline. The third end of the gas-water separator is connected to the second end of the evaporator through a pipeline. The third end of the evaporator is connected to the first end of the first reformer through a pipeline. The second end of the first reformer is connected to the first end of the first-level fuel cell stack through a pipeline. The second end of the first-level fuel cell stack is connected to the first end of the condenser through a pipeline. The second end of the gas-water separator is connected to the first end of the second fuel mixer through a pipeline. The second end of the second fuel mixer is connected to the first end of the second reformer through a pipeline. The third end of the second fuel mixer is used to receive external fresh fuel. The second end of the second reformer is connected to the first end of the second-level fuel cell stack through a pipeline. The second end of the second-level fuel cell stack is connected to the first end of the burner through a pipeline. The second end of the burner is connected to the first end of the air preheater through a pipeline. The second end of the air preheater is connected to the third end of the first reformer through a pipeline. The third end of the air preheater is used to receive air. The third end of the first-level fuel cell stack is connected to the first end of the air mixer through a pipeline. The second end of the air mixer is connected to the third end of the second-level fuel cell stack through a pipeline. The third end of the air mixer is used to receive air.

[0022] Optionally, the fuel cell system further includes:

[0023] A pressure sensor, which is arranged on the pipeline at the first end of the first-level fuel cell stack; the controller is electrically connected to the pressure sensor;

[0024] The controller is used to obtain the actual pressure at the first end of the first-level fuel cell stack through the pressure sensor.

[0025] Optionally, the fuel cell system further includes:

[0026] A temperature sensor, which is arranged on the pipeline at the fourth end of the condenser; the controller is electrically connected to the temperature sensor;

[0027] The controller is used to obtain the actual temperature at the fourth end of the condenser through the temperature sensor.

[0028] Optionally, the fuel cell system further includes:

[0029] A coolant flowmeter, which is arranged on the coolant pipeline at the first end of the coolant pump; the controller is electrically connected to the coolant flowmeter;

[0030] The controller is used to control and adjust the coolant flow regulated by the coolant pump according to the set temperature to be adjusted, and to monitor the coolant flow in real time through the coolant flowmeter until the set temperature to be adjusted is reached, and to determine that the actual pressure at the first end of the first-level fuel cell stack is less than or equal to the pressure safety threshold.

[0031] According to another aspect of the present invention, there is provided a control method for a fuel cell system, including the fuel cell system described in any embodiment of the present invention;

[0032] The control method for a fuel cell system includes:

[0033] The controller obtains the actual pressure at the first end of the first-stage stack and the pressure safety threshold of the first-stage stack;

[0034] When the actual pressure at the first end of the first-stage stack is greater than the pressure safety threshold, the controller determines the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold;

[0035] The controller determines the deviation value of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold;

[0036] The controller determines the temperature difference corresponding to the deviation value of the gaseous fuel according to the corresponding relationship between the temperature and the content of the gaseous fuel;

[0037] The controller obtains the actual temperature at the fourth end of the condenser, and determines the set temperature to be adjusted according to the actual temperature at the fourth end of the condenser and the temperature difference;

[0038] The controller controls the coolant flow rate adjusted by the cooling water pump according to the set temperature to be adjusted until the set temperature to be adjusted is reached, and determines that the actual pressure at the first end of the first-stage stack is less than or equal to the pressure safety threshold.

[0039] Optionally, the controller determines the flow rate of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold; and determines the deviation value of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the flow rate of the gaseous fuel separated by the gas-liquid separator.

[0040] Optionally, when the actual pressure at the first end of the first-stage stack is greater than or equal to the pressure safety threshold, the controller determines that the first-stage stack is operating safely.

[0041] The fuel cell system provided by the embodiment of the present invention includes: a primary fuel cell stack, a cooling water pump, a condenser, a gas-water separator, a secondary fuel cell stack, and a controller; the controller is configured to: obtain the actual pressure at the first end of the primary fuel cell stack and the pressure safety threshold of the primary fuel cell stack; when the actual pressure at the first end of the primary fuel cell stack is greater than the pressure safety threshold, determine the difference between the actual pressure at the first end of the primary fuel cell stack and the pressure safety threshold; determine the deviation value of the gaseous fuel separated by the gas-water separator in the pipeline according to the difference between the actual pressure at the first end of the primary fuel cell stack and the pressure safety threshold; determine the temperature difference corresponding to the deviation value of the gaseous fuel according to the corresponding relationship between the temperature and the content of the gaseous fuel; obtain the actual temperature at the fourth end of the condenser, and determine the set temperature to be adjusted according to the actual temperature at the fourth end of the condenser and the temperature difference; adjust the coolant flow rate adjusted by the cooling water pump according to the set temperature to be adjusted until the set temperature to be adjusted is reached, and determine that the actual pressure at the first end of the primary fuel cell stack is less than or equal to the pressure safety threshold. By adjusting the coolant flow rate adjusted by the cooling water pump, the cooling capacity of the condenser is adjusted in the embodiment of the present invention, and then the actual temperature at the fourth end of the condenser is adjusted. The regulation of the actual temperature at the fourth end of the condenser will be intuitively reflected in the actual pressure at the first end of the primary fuel cell stack, so as to realize the control of the actual pressure at the first end of the primary fuel cell stack, avoid the actual pressure at the first end of the primary fuel cell stack from being too high, and ensure that the primary fuel cell stack operates within the safe pressure boundary.

[0042] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used 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

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0044] Figure 1 It is a schematic structural diagram of a fuel cell system provided by Embodiment 1 of the present invention.

[0045] Figure 2 It is a schematic structural diagram of another fuel cell system provided by Embodiment 1 of the present invention.

[0046] Figure 3 It is a flowchart of a control method for a fuel cell system provided by Embodiment 2 of the present invention. Detailed Description of the Embodiments

[0047] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances 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 "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0049] Embodiment 1

[0050] The embodiment of the present invention provides a fuel cell system. Figure 1 is a schematic structural diagram of a fuel cell system provided by Embodiment 1 of the present invention. Refer to Figure 1 , the fuel cell system includes: a primary stack 10, a cooling water pump 20, a condenser 30, a gas-liquid separator 40, a secondary stack 50 and a controller; the second end of the primary stack 10 is connected to the first end of the condenser 30 through a pipeline; the first end of the cooling water pump 20 and the second end of the condenser 30 are connected through a coolant pipeline, the third end of the condenser 30 and the second end of the cooling water pump 20 are connected through a coolant pipeline, the fourth end of the condenser 30 is connected to the first end of the gas-liquid separator 40 through a pipeline, the second end of the gas-liquid separator 40 is connected to the first end of the secondary stack 50 through a pipeline, and the third end of the gas-liquid separator 40 is also connected to the first end of the primary stack 10 through a pipeline; the controller is electrically connected to the primary stack 10, the cooling water pump 20, the condenser 30, the gas-liquid separator 40 and the secondary stack 50.

[0051] The controller is configured to: obtain the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold of the first-stage stack 10; when the actual pressure at the first end of the first-stage stack 10 is greater than the pressure safety threshold, determine the difference between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold; based on the difference between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold, determine the deviation value of the gaseous fuel separated by the gas-liquid separator 40 in the pipeline; according to the corresponding relationship between the temperature and the content of the gaseous fuel, determine the temperature difference corresponding to the deviation value of the gaseous fuel; obtain the actual temperature at the fourth end of the condenser 30, and based on the actual temperature at the fourth end of the condenser 30 and the temperature difference, determine the set temperature to be adjusted; according to the set temperature to be adjusted, adjust the coolant flow rate adjusted by the cooling water pump 20 until the set temperature to be adjusted is reached, and determine that the actual pressure at the first end of the first-stage stack 10 is less than or equal to the pressure safety threshold.

[0052] wherein the controller is not shown in Figure 1 The first-stage stack 10 and the second-stage stack 50 both include an anode, an electrolyte, and a cathode. The anode exhaust gas of the first-stage stack 10 is transported to the condenser 30, and the cooling water pump 20 transports the coolant to the condenser 30, where the anode exhaust gas of the first-stage stack 10 is cooled. At this time, the anode exhaust gas of the first-stage stack 10 is a mixed fluid of liquid water and gaseous fuel. The mixed fluid is transported to the gas-liquid separator 40, and the gas-liquid separator 40 separates the gas and water from the mixed fluid under the action of gravity to obtain liquid water and gaseous fuel; the gaseous fuel is transported to the second-stage stack 50 to provide fuel for the second-stage stack 50. By using the anode exhaust gas of the first-stage stack 10 to provide gaseous fuel for the second-stage stack 50 in the embodiment of the present invention, the tail gas emission can be reduced; and the liquid water can be transported to the first-stage stack 10 to provide fuel for the first-stage stack 10, which can reduce the material cost and the tail gas emission.

[0053] From the perspective of the fuel flow process, when no external fresh fuel is added, only the content of the gaseous fuel separated by the gas-liquid separator 40 will affect the flow rate entering the anode side of the second-stage stack, that is, affect the anode side pressure drop of the second-stage stack. Therefore, when the system is operating stably, the pressure at the first end of the first-stage stack 10 is directly affected by the content of the gaseous fuel separated by the gas-liquid separator 40 from its anode exhaust gas. Since the content of the gaseous fuel separated by the gas-liquid separator 40 is affected by the cooling capacity of the condenser 30, adjusting the cooling capacity of the condenser can ensure that the pressure at the first end of the first-stage stack 10 does not exceed the pressure safety threshold.

[0054] Exemplarily, the actual pressure at the first end of the first-stage stack 10 can be measured by a pressure sensor. The actual pressure at the first end of the first-stage stack 10 is the inlet pressure of the first-stage stack. The pressure safety threshold of the first-stage stack 10 can be measured through experiments. If it exceeds the pressure safety threshold, there is a risk that the anode pressure in the first-stage stack 10 is too high and the battery cells of the first-stage stack 10 are at risk of being punctured. The controller determines the relationship between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold of the first-stage stack 10. When the actual pressure at the first end of the first-stage stack 10 is less than the pressure safety threshold of the first-stage stack 10, it is determined that the actual pressure at the first end of the first-stage stack 10 is within the safe range. The system does not need to be regulated, and the current operating state is maintained, which can avoid excessive pressure in the first-stage stack 10 and ensure that the first-stage stack 10 operates within the safe pressure boundary.

[0055] When the actual pressure at the first end of the first-stage stack 10 is greater than the pressure safety threshold, the controller calculates the difference between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold by subtracting the actual pressure at the first end of the first-stage stack 10 from the pressure safety threshold. According to the difference between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold, the flow rate of the gaseous fuel separated by the gas-liquid separator 40 in the pipeline is determined; according to the flow rate of the gaseous fuel separated by the gas-liquid separator 40, the deviation value of the gaseous fuel separated by the gas-liquid separator 40 in the pipeline is determined; according to the corresponding relationship between the temperature and the content of the gaseous fuel, the temperature difference corresponding to the deviation value of the gaseous fuel is determined. For example, when the temperature is 20 °C, the corresponding content of the gaseous fuel is 10%; when the temperature is 30 °C, the corresponding content of the gaseous fuel is 15%; when the temperature is 40 °C, the corresponding content of the gaseous fuel is 20%; therefore, if the deviation value of the gaseous fuel is 10%, the corresponding temperature difference is 20 °C.

[0056] The actual temperature of the fourth end of the condenser 30 can be measured by a temperature sensor. The controller calculates the set temperature to be adjusted by subtracting the temperature difference from the actual temperature of the fourth end of the condenser 30 based on the actual temperature of the fourth end of the condenser 30 and the temperature difference. According to the set temperature to be adjusted, the coolant flow rate adjusted by the cooling water pump 20 is adjusted. Exemplarily, the rotational speed of the cooling water pump 20 can be increased by using PID adjustment to improve the cooling capacity of the condenser 30, thereby increasing the coolant flow rate, reducing the actual temperature of the fourth end of the condenser 30 until the set temperature to be adjusted is reached, and ensuring that the actual pressure at the first end of the first-stage stack 10 is less than or equal to the pressure safety threshold. In the embodiment of the present invention, the cooling capacity of the condenser 30 is adjusted by the coolant flow rate adjusted by the cooling water pump 20, and then the actual temperature of the fourth end of the condenser 30 is adjusted. The control of the actual temperature of the fourth end of the condenser 30 will be intuitively reflected in the actual pressure at the first end of the first-stage stack 10, thereby realizing the control of the actual pressure at the first end of the first-stage stack 10, avoiding the excessive actual pressure at the first end of the first-stage stack 10, and ensuring that the first-stage stack 10 operates within the safe pressure boundary.

[0057] The fuel cell system provided by the embodiment of the present invention includes: a first-stage stack 10, a cooling water pump 20, a condenser 30, a gas-water separator 40, a second-stage stack 50, and a controller. The controller is configured to: obtain the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold of the first-stage stack 10; when the actual pressure at the first end of the first-stage stack 10 is greater than the pressure safety threshold, determine the difference between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold; determine the deviation value of the gaseous fuel separated by the gas-water separator 40 in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold; determine the temperature difference corresponding to the deviation value of the gaseous fuel according to the corresponding relationship between the temperature and the content of the gaseous fuel; obtain the actual temperature of the fourth end of the condenser 30, and determine the set temperature to be adjusted according to the actual temperature of the fourth end of the condenser 30 and the temperature difference; adjust the coolant flow rate adjusted by the cooling water pump 20 according to the set temperature to be adjusted until the set temperature to be adjusted is reached, and ensure that the actual pressure at the first end of the first-stage stack 10 is less than or equal to the pressure safety threshold. In the embodiment of the present invention, the cooling capacity of the condenser 30 is adjusted by the coolant flow rate adjusted by the cooling water pump 20, and then the actual temperature of the fourth end of the condenser 30 is adjusted. The control of the actual temperature of the fourth end of the condenser 30 will be intuitively reflected in the actual pressure at the first end of the first-stage stack 10, thereby realizing the control of the actual pressure at the first end of the first-stage stack 10, avoiding the excessive actual pressure at the first end of the first-stage stack 10, and ensuring that the first-stage stack 10 operates within the safe pressure boundary.

[0058] Optionally, the controller is configured to determine the flow rate of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold; and determine the deviation value of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the flow rate of the gaseous fuel separated by the gas-liquid separator.

[0059] Wherein, according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold, the flow rate of the gaseous fuel separated by the gas-liquid separator in the pipeline can be determined through a fluid mechanics formula. According to the flow rate of the gaseous fuel separated by the gas-liquid separator and the cross-sectional area of the pipeline where the gaseous fuel is located, the deviation value of the gaseous fuel separated by the gas-liquid separator in the pipeline can be determined. The deviation value of the gaseous fuel is the excess amount of the gaseous fuel.

[0060] Optionally, the controller is further configured to determine that the first-stage stack is operating safely when the actual pressure at the first end of the first-stage stack is greater than or equal to the pressure safety threshold.

[0061] Wherein, when the actual pressure at the first end of the first-stage stack is less than the pressure safety threshold of the first-stage stack, the controller determines that the actual pressure at the first end of the first-stage stack is within the safe range, and the system does not need to be regulated. By maintaining the current operating state, the pressure of the first-stage stack can be prevented from being too high, ensuring that the first-stage stack operates within the safe pressure boundary.

[0062] Optionally, Figure 2 is a schematic structural diagram of another fuel cell system provided in Embodiment 1 of the present invention. Referring to Figure 2 , the fuel cell system further includes: a first fuel mixer 60, an evaporator 70, a first reformer 80, an air preheater 90, an air mixer 100, a second fuel mixer 110, a second reformer 120, and a burner 130; the controller is electrically connected to the first fuel mixer 60, the evaporator 70, the first reformer 80, the air preheater 90, the air mixer 100, the second fuel mixer 110, the second reformer 120, and the burner 130.

[0063] The first end of the first fuel mixer 60 is used to receive external fresh fuel. The second end of the first fuel mixer 60 is connected to the first end of the evaporator 70 through a pipeline. The third end of the gas-water separator 40 is connected to the second end of the evaporator 70 through a pipeline. The third end of the evaporator 70 is connected to the first end of the first reformer 80 through a pipeline. The second end of the first reformer 80 is connected to the first end of the first-stage fuel cell stack 10 through a pipeline. The second end of the first-stage fuel cell stack 10 is connected to the first end of the condenser 30 through a pipeline. The second end of the gas-water separator 40 is connected to the first end of the second fuel mixer 110 through a pipeline. The second end of the second fuel mixer 110 is connected to the first end of the second reformer 120 through a pipeline. The third end of the second fuel mixer 110 is used to receive external fresh fuel. The second end of the second reformer 120 is connected to the first end of the second-stage fuel cell stack 50 through a pipeline. The second end of the second-stage fuel cell stack 50 is connected to the first end of the burner 130 through a pipeline. The second end of the burner 130 is connected to the first end of the air preheater 90 through a pipeline. The second end of the air preheater 90 is connected to the third end of the first reformer 80 through a pipeline. The third end of the air preheater 90 is used to receive air. The third end of the first-stage fuel cell stack 10 is connected to the first end of the air mixer 100 through a pipeline. The second end of the air mixer 100 is connected to the third end of the second-stage fuel cell stack 50 through a pipeline. The third end of the air mixer 100 is used to receive air.

[0064] Specifically, the controller is not shown in Figure 2 The first-stage fuel cell stack 10 and the second-stage fuel cell stack 50 both include an anode, an electrolyte, and a cathode. The anode sides of the first-stage fuel cell stack 10 and the second-stage fuel cell stack 50 are arranged in series. The specific working process is as follows: The burner 130 provides the main heat source for the entire fuel cell system. Its fuel is the anode exhaust gas discharged from the second-stage fuel cell stack 50, and the combustion-supporting substance is the air output from the cathode of the second-stage fuel cell stack 50. The anode exhaust gas burns in the burner 130 to provide heat for the air preheater 90. The liquid water separated by the steam-water separator 40 is transported to the evaporator 70. The external fresh fuel received by the first fuel mixer 60 enters the evaporator 70, and a fuel and superheated steam mixture gas is generated in the evaporator 70. The mixture gas enters the first reformer 80, and a steam reforming reaction occurs in the first reformer 80. The fuel after the reforming reaction enters the first-stage fuel cell stack 10 to undergo an electrochemical reaction. The anode exhaust gas discharged from the first-stage fuel cell stack 10 enters the condenser 30, and under the action of the coolant, the water vapor in the anode exhaust gas condenses into liquid water. The anode exhaust gas of the first-stage fuel cell stack 10 rich in liquid water enters the gas-water separator 40 to separate the liquid water and gaseous fuel. Subsequently, the gaseous fuel is mixed with the external fresh fuel and then enters the second reformer 120, and the second reformer 120 undergoes a reaction. The condensed liquid water enters the evaporator 70.

[0065] Exemplarily, a condenser 30 inlet pressure sensor and a condenser 30 inlet temperature sensor can also be sequentially arranged on the pipeline between the first-stage stack 10 and the condenser 30; the condenser 30 inlet pressure sensor is used to monitor the inlet pressure of the first end of the condenser in real time, and the condenser 30 inlet temperature sensor is used to monitor the inlet temperature of the first end of the condenser in real time. A condenser 30 outlet temperature sensor and a condenser 30 outlet pressure sensor can also be sequentially arranged on the pipeline between the condenser 30 and the steam-water separator 40; the condenser 30 outlet pressure sensor is used to monitor the outlet pressure of the fourth end of the condenser in real time, and the condenser 30 outlet temperature sensor is used to monitor the outlet temperature of the fourth end of the condenser in real time. A condenser 30 coolant inlet temperature sensor and a condenser 30 coolant inlet pressure sensor can also be sequentially arranged on the pipeline of the second end of the condenser 30; the condenser 30 coolant inlet pressure sensor is used to monitor the inlet pressure of the second end of the condenser 30 in real time, and the condenser 30 coolant inlet temperature sensor is used to monitor the inlet temperature of the second end of the condenser 30 in real time. A condenser 30 coolant outlet temperature sensor and a condenser 30 coolant outlet pressure sensor can also be sequentially arranged on the pipeline of the third end of the condenser 30; the condenser 30 coolant outlet pressure sensor is used to monitor the outlet pressure of the third end of the condenser 30 in real time, and the condenser 30 coolant outlet temperature sensor is used to monitor the outlet temperature of the third end of the condenser 30 in real time. A steam-water separator 40 outlet temperature sensor and a steam-water separator 40 outlet relative humidity sensor can also be sequentially arranged on the pipeline of the second end of the steam-water separator 40; the steam-water separator 40 outlet temperature sensor is used to monitor the outlet temperature of the steam-water separator in real time, and the steam-water separator 40 outlet relative humidity sensor is used to monitor the outlet relative humidity of the steam-water separator in real time; an inlet pressure sensor and an inlet temperature sensor can also be arranged at the first end of the second-stage stack 50; the inlet pressure sensor is used to monitor the inlet pressure of the first end of the second-stage stack 50 in real time, and the inlet temperature sensor is used to monitor the inlet temperature of the first end of the second-stage stack 50 in real time. The controller is electrically connected to all the sensors to ensure that the operating state of the fuel cell system can be monitored in real time.

[0066] Optionally, referring to Figure 2 , the fuel cell system further includes: a pressure sensor 01, and the pressure sensor 01 is arranged on the pipeline at the first end of the first-stage stack 10; the controller is electrically connected to the pressure sensor 01; the controller is used to obtain the actual pressure at the first end of the first-stage stack 10 through the pressure sensor 01.

[0067] Among them, the pressure sensor 01 can measure the actual pressure at the second end of the first-stage stack 10 in real time, ensuring that the relationship between the actual pressure at the first end of the first-stage stack 10 and the pressure safety threshold can be intuitively displayed, avoiding excessive actual pressure at the first end of the first-stage stack 10, and ensuring that the first-stage stack 10 operates within the safe pressure boundary.

[0068] Optionally, referring to Figure 2 , the fuel cell system further includes: a temperature sensor 02, which is disposed on the pipeline at the fourth end of the condenser 30; the controller is electrically connected to the temperature sensor 02; the controller is configured to obtain the actual temperature at the fourth end of the condenser through the temperature sensor 02.

[0069] Among them, the temperature sensor 02 can measure the actual temperature at the fourth end of the condenser 30 in real time, adjust the cooling capacity of the condenser 30 by adjusting the coolant flow rate regulated by the cooling water pump 20, and then adjust the actual temperature at the fourth end of the condenser 30, and can monitor the actual temperature at the fourth end of the condenser 30 until the set temperature to be adjusted is reached, determine that the actual pressure at the first end of the first-stage stack 10 is less than or equal to the pressure safety threshold, avoid excessive actual pressure at the first end of the first-stage stack 10, and ensure that the first-stage stack 10 operates within the safe pressure boundary.

[0070] Optionally, referring to Figure 2 , the fuel cell system further includes: a coolant flowmeter 03, which is disposed on the coolant pipeline at the first end of the cooling water pump 20; the controller is electrically connected to the coolant flowmeter 03; the controller is configured to control and adjust the coolant flow rate regulated by the cooling water pump according to the set temperature to be adjusted, and monitor the coolant flow rate in real time through the coolant flowmeter until the set temperature to be adjusted is reached, and determine that the actual pressure at the first end of the stack is less than or equal to the pressure safety threshold.

[0071] Among them, the coolant flowmeter 03 can measure the coolant flow rate in real time. A coolant flowmeter 02 is disposed on the coolant pipeline between the cooling water pump 20 and the condenser 30. When the rotation speed of the cooling water pump 20 is increased, the coolant flowmeter 02 measures an increase in the coolant flow rate, causing the temperature in the pipeline to decrease until the set temperature to be adjusted is reached, determining that the actual pressure at the first end of the first-stage stack 10 is less than or equal to the pressure safety threshold, avoiding excessive actual pressure at the first end of the first-stage stack 10, and ensuring that the first-stage stack 10 operates within the safe pressure boundary.

[0072] Embodiment 2

[0073] On the basis of the above embodiments, the present invention provides a control method for a fuel cell system, including the fuel cell system of any embodiment of the present invention.

[0074] Figure 3 is a flowchart of a control method for a fuel cell system provided in Embodiment 2 of the present invention. Refer to Figure 3 , the control method of the fuel cell system includes:

[0075] S210. The controller obtains the actual pressure at the first end of the first-stage stack and the pressure safety threshold of the first-stage stack;

[0076] S220. When the actual pressure at the first end of the first-stage stack is greater than the pressure safety threshold, the controller determines the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold;

[0077] S230. The controller determines the deviation value of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold;

[0078] S240. The controller determines the temperature difference corresponding to the deviation value of the gaseous fuel according to the corresponding relationship between the temperature and the content of the gaseous fuel;

[0079] S250. The controller obtains the actual temperature at the fourth end of the condenser, and determines the set temperature to be adjusted according to the actual temperature at the fourth end of the condenser and the temperature difference;

[0080] S260. The controller controls the coolant flow rate adjusted by the cooling water pump according to the set temperature to be adjusted until the set temperature to be adjusted is reached, and determines that the actual pressure at the first end of the first-stage stack is less than or equal to the pressure safety threshold.

[0081] The control method of the fuel cell system provided by the embodiment of the present invention adjusts the cooling capacity of the condenser by adjusting the coolant flow rate of the cooling water pump, and then adjusts the actual temperature at the fourth end of the condenser. The control of the actual temperature at the fourth end of the condenser will be intuitively reflected in the actual pressure at the first end of the first-stage stack, so as to realize the control of the actual pressure at the first end of the first-stage stack, avoid the actual pressure at the first end of the first-stage stack from being too high, and ensure that the first-stage stack operates within the safe pressure boundary.

[0082] Optionally, the controller determines the flow rate of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold; and determines the deviation value of the gaseous fuel separated by the gas-liquid separator in the pipeline according to the flow rate of the gaseous fuel separated by the gas-liquid separator.

[0083] Optionally, when the actual pressure at the first end of the first-stage stack is greater than or equal to the pressure safety threshold, the controller determines that the first-stage stack is operating safely.

[0084] The control method of the fuel cell system provided by the technical solution of the embodiment of the present invention has the same beneficial effects as the fuel cell system described in any embodiment of the present invention.

[0085] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. 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 no limitation is made herein.

[0086] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fuel cell system, characterized in that: include: First-stage fuel cell stack, cooling water pump, condenser, gas-water separator, second-stage fuel cell stack and controller; The second end of the first-stage stack is connected to the first end of the condenser through a pipeline; the first end of the cooling water pump is connected to the second end of the condenser through a coolant pipeline, the third end of the condenser is connected to the second end of the cooling water pump through a coolant pipeline, the fourth end of the condenser is connected to the first end of the gas-water separator through a pipeline, the second end of the gas-water separator is connected to the first end of the second-stage stack through a pipeline, and the third end of the gas-water separator is also connected to the first end of the first-stage stack through a pipeline; The controller is electrically connected to the primary stack, the cooling water pump, the condenser, the gas-water separator and the secondary stack; The controller is used to: Acquire the actual pressure of the first end of the first-stage fuel cell stack and the pressure safety threshold of the first-stage fuel cell stack; When the actual pressure at the first end of the first-stage stack is greater than the pressure safety threshold, determining the difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold; Determining a deviation value of the gas fuel separated by the gas-water separator in the pipeline according to a difference between an actual pressure at the first end of the first-stage fuel cell stack and the pressure safety threshold; Determining the temperature difference corresponding to the deviation value of the gas fuel according to the corresponding relationship between the temperature and the content of the gas fuel; Acquiring the actual temperature of the fourth end of the condenser, and determining the set temperature to be adjusted according to the actual temperature of the fourth end of the condenser and the temperature difference; According to the set temperature that needs to be adjusted, the coolant flow regulated by the cooling water pump is adjusted until the set temperature that needs to be adjusted is reached, and it is determined that the actual pressure at the first end of the first-level fuel cell stack is less than or equal to the pressure safety threshold.

2. The fuel cell system according to claim 1, characterized in that: The controller is used to determine the flow rate of the gas fuel separated by the gas-water separator in the pipeline based on the difference between the actual pressure at the first end of the first-stage fuel stack and the pressure safety threshold; and determine the deviation value of the gas fuel separated by the gas-water separator in the pipeline based on the flow rate of the gas fuel separated by the gas-water separator.

3. The fuel cell system according to claim 1, characterized in that: The controller is also used to determine that the first-stage fuel cell stack is operating safely when the actual pressure at the first end of the first-stage fuel cell stack is greater than or equal to the pressure safety threshold.

4. The fuel cell system according to claim 1, characterized in that: Also includes: a first fuel mixer, an evaporator, a first reformer, an air preheater, an air mixer, a second fuel mixer, a second reformer, and a burner; The controller is electrically connected to the first fuel mixer, the evaporator, the first reformer, the air preheater, the air mixer, the second fuel mixer, the second reformer and the burner; The first end of the first fuel mixer is used to receive fresh fuel from the outside, the second end of the first fuel mixer is connected to the first end of the evaporator through a pipeline, the third end of the gas-water separator is connected to the second end of the evaporator through a pipeline, the third end of the evaporator is connected to the first end of the first reformer through a pipeline, the second end of the first reformer is connected to the first end of the first-stage stack through a pipeline; the second end of the first-stage stack is connected to the first end of the condenser through a pipeline; the second end of the gas-water separator is connected to the first end of the second fuel mixer through a pipeline, the second end of the second fuel mixer is connected to the first end of the second reformer through a pipeline, The third end of the second fuel mixer is used to receive external fresh fuel, the second end of the second reformer is connected to the first end of the secondary fuel stack through a pipeline, the second end of the secondary fuel stack is connected to the first end of the burner through a pipeline, the second end of the burner is connected to the first end of the air preheater through a pipeline; the second end of the air preheater is connected to the third end of the first reformer through a pipeline, and the third end of the air preheater is used to receive air; the third end of the first fuel stack is connected to the first end of the air mixer through a pipeline, the second end of the air mixer is connected to the third end of the secondary fuel stack through a pipeline, and the third end of the air mixer is used to receive air.

5. The fuel cell system according to claim 1, characterized in that: Also includes: A pressure sensor, wherein the pressure sensor is arranged on a pipeline at a first end of the first-stage fuel cell stack; The controller is electrically connected to the pressure sensor; The controller is used to obtain the actual pressure of the first end of the first-stage fuel cell stack through the pressure sensor.

6. The fuel cell system according to claim 1, characterized in that: Also includes: A temperature sensor, wherein the temperature sensor is arranged on a pipeline at a fourth end of the condenser; The controller is electrically connected to the temperature sensor; The controller is used to obtain the actual temperature of the fourth end of the condenser through the temperature sensor.

7. The fuel cell system according to claim 2, characterized in that: Also includes: A coolant flow meter, the coolant flow meter is arranged on the coolant pipeline at the first end of the cooling water pump; The controller is electrically connected to the coolant flow meter; The controller is used to control and adjust the coolant flow regulated by the cooling water pump according to the set temperature that needs to be adjusted, monitor the coolant flow in real time through the coolant flow meter until the set temperature that needs to be adjusted is reached, and determine that the actual pressure at the first end of the first-level fuel cell stack is less than or equal to the pressure safety threshold.

8. A control method for a fuel cell system, characterized in that: A fuel cell system comprising any one of claims 1 to 7; A control method for a fuel cell system, comprising: The controller obtains the actual pressure of the first end of the first-stage fuel cell stack and the pressure safety threshold of the first-stage fuel cell stack; The controller determines a difference between the actual pressure at the first end of the first-stage stack and the pressure safety threshold when the actual pressure at the first end of the first-stage stack is greater than the pressure safety threshold; The controller determines a deviation value of the gas fuel separated by the gas-water separator in the pipeline according to a difference between an actual pressure at the first end of the first-stage fuel cell stack and the pressure safety threshold; The controller determines the temperature difference corresponding to the deviation value of the gas fuel according to the corresponding relationship between the temperature and the content of the gas fuel; The controller obtains the actual temperature of the fourth end of the condenser, and determines the set temperature to be adjusted according to the actual temperature of the fourth end of the condenser and the temperature difference; The controller controls and adjusts the coolant flow regulated by the cooling water pump according to the set temperature that needs to be adjusted until the set temperature that needs to be adjusted is reached, and determines that the actual pressure at the first end of the first-level fuel cell stack is less than or equal to the pressure safety threshold.

9. The control method of the fuel cell system according to claim 8, characterized in that: The controller determines the flow rate of the gas fuel separated by the gas-water separator in the pipeline based on the difference between the actual pressure at the first end of the first-stage fuel stack and the pressure safety threshold; and determines the deviation value of the gas fuel separated by the gas-water separator in the pipeline based on the flow rate of the gas fuel separated by the gas-water separator.

10. The control method of the fuel cell system according to claim 8, characterized in that: The controller determines that the first-stage stack is operating safely when the actual pressure at the first end of the first-stage stack is greater than or equal to the pressure safety threshold.

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