Fuel cell system and control method

Abstract

The invention discloses a fuel cell system and a control method, and the fuel cell system comprises an electric pile which is connected with an air compressor through an air supply pipeline; the expansion machine is selectively communicated with the electric pile through a recovery pipeline; and the DCDC module is connected with the electric pile, and the DCDC module is suitable for being electrically connected with the expansion machine and performing grid-connected power supply when the expansion machine meets the power supply condition. According to the fuel cell system provided by the embodiment of the invention, efficient operation can be realized, energy recovery can be effectively carried out on waste gas and the like generated by the fuel cell system, and meanwhile, the recovered energy can be stably supplied to a load by arranging the DCDC module under the condition that the efficient operation of the fuel cell system is not influenced, so that energy reutilization is realized, and the energy utilization rate is improved. The use cost is saved, the use effect is better, and the application range is wider.

Description

Technical Field

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

[0002] During the operation of the fuel cell system, the air compressor compresses the air and passes it into the fuel cell stack for electrochemical reaction, generating electricity and driving the load. The unreacted air is discharged from the fuel cell stack and then discharged into the atmosphere after passing through the emission and silencer system. Since this part of the gas still has a certain pressure and flow rate, it would be a certain amount of waste if it is not utilized and directly discharged. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a fuel cell system that can operate efficiently and effectively recover energy while also driving a load to operate stably.

[0004] A fuel cell system according to an embodiment of the present invention includes: a fuel cell stack, which is connected to an air compressor via an air supply pipeline; an expander, which is selectively connected to the fuel cell stack via a recovery pipeline; a DCDC module, which is connected to the fuel cell stack, and is suitable for being electrically connected to the expander and connected to the grid for power supply when the expander meets power supply conditions.

[0005] According to the fuel cell system of the embodiment of the present invention, the fuel cell system can achieve efficient operation and can effectively recover energy from the exhaust gas generated by it. At the same time, by setting a DCDC module, the recovered energy can stably supply energy to the load without affecting the efficient operation of the fuel cell system, thereby achieving energy reuse, saving use costs, better use effects, and a wider range of applications.

[0006] In the fuel cell system according to some embodiments of the present invention, the expander is connected to the air compressor, and the expander is configured to be non-coaxial with the air compressor.

[0007] According to the fuel cell system of some embodiments of the present invention, the recovery pipeline includes a main circuit, a first branch circuit and a second branch circuit, the main circuit is connected to the fuel cell stack, the first branch circuit and the second branch circuit are selectively connected to the main circuit respectively, the first branch circuit is connected to the expander, and the second branch circuit is suitable for being connected to the external atmosphere.

[0008] According to some embodiments of the fuel cell system of the present invention, a recovery valve is provided in the recovery pipeline, and the recovery valve is provided with an inlet, a first outlet and a second outlet, the inlet is connected to the main road, the first outlet is connected to the first branch, the second outlet is connected to the second branch, and the inlet is suitable for selectively connecting to the first outlet or the second outlet.

[0009] In the fuel cell system according to some embodiments of the present invention, a back pressure valve is provided in the main path.

[0010] According to some embodiments of the present invention, the fuel cell system further includes a bypass branch, which is connected between the gas supply pipeline and the main pipeline, and a bypass valve is provided in the bypass branch.

[0011] According to the fuel cell system of some embodiments of the present invention, an intercooler and a humidifier are provided in the gas supply pipeline, and a shut-off valve is provided in the gas supply pipeline between the humidifier and the fuel cell stack.

[0012] The invention also provides a control method for the fuel cell system.

[0013] A control method for a fuel cell system according to an embodiment of the present invention includes:

[0014] Obtaining the operating status of the fuel cell system;

[0015] When the operating state meets the set operating conditions, the recovery pipeline is controlled to be connected and the expander is started to operate;

[0016] obtaining a voltage state of the expander;

[0017] When the voltage state meets the set voltage condition, the DCDC module is controlled to connect to the grid for power supply.

[0018] According to some embodiments of the present invention, the control method of the fuel cell system includes, when the operating state satisfies the set operating condition:

[0019] Obtaining an operational stability value of the fuel cell system;

[0020] When the operation stability value is greater than the set stability value, determining that the operation state meets the set operation condition;

[0021] And / or, when the voltage state satisfies a set voltage condition, the method includes:

[0022] obtaining an output voltage of the expander;

[0023] When the output voltage is greater than the set voltage, it is determined that the voltage state satisfies the set voltage condition.

[0024] The control method of the fuel cell system according to some embodiments of the present invention further includes:

[0025] Obtaining the operating status of the fuel cell system;

[0026] When shutdown or failure occurs in the operating state, the recovery pipeline is controlled to be disconnected so that the expander stops running, and the grid-connected power supply of the DCDC module is cut off.

[0027] The control method of the fuel cell system has the same advantages as the above-mentioned fuel cell system over the prior art, which will not be described in detail here.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0030] Figure 1 is a schematic diagram of a gas pipeline of a fuel cell system according to an embodiment of the present invention;

[0031] Figure 2 FIG. 1 is a flow chart of a control method for a fuel cell system according to an embodiment of the present invention. Figure 1 ;

[0032] Figure 3 FIG. 1 is a flow chart of a control method for a fuel cell system according to an embodiment of the present invention. Figure 2 ;

[0033] Figure 4 FIG. 1 is a flow chart of a control method for a fuel cell system according to an embodiment of the present invention. Figure 3 ;

[0034] Figure 5 FIG. 1 is a flow chart of a control method for a fuel cell system according to an embodiment of the present invention. Figure 4 ;

[0035] Figure 6 Schematic diagram of the implementation steps of the control method of the fuel cell system according to an embodiment of the present invention.

[0036] Reference numerals:

[0037] A fuel cell system 100,

[0038] Fuel stack 1, air compressor 2, expander 3, DCDC module 4, recovery valve 5, inlet 51, first outlet 52, second outlet 53, back pressure valve 6, bypass valve 7, intercooler 8, humidifier 9, stop valve 10, hydrogen pressure regulating valve 11, nitrogen and water discharge valve 12, gas-water separator 13,

[0039] Main road 141, first branch road 142, second branch road 143,

[0040] Gas supply pipeline 15, bypass branch 16, hydrogen medium-pressure pipeline 17. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Reference below Figure 1 A fuel cell system 100 according to an embodiment of the present invention is described. The fuel cell system 100 can operate efficiently and effectively recover energy while driving a load to operate stably.

[0045] like Figure 1 As shown, the fuel cell system 100 according to an embodiment of the present invention includes: a fuel cell stack 1, an expander 3 and a DCDC module 4.

[0046] The fuel cell stack 1 is connected to the air compressor 2 through the air supply pipeline 15, the expander 3 is selectively connected to the fuel cell stack 1 through the recovery pipeline, the DCDC module 4 is connected to the fuel cell stack 1, and the DCDC module 4 is suitable for being electrically connected to the expander 3 and connected to the grid for power supply when the expander 3 meets the power supply conditions.

[0047] Among them, the fuel cell system 100 refers to a system for supplying energy on board a ship or vehicle, etc. It is different from a traditional engine system. It can use hydrogen and oxygen to produce an electrochemical reaction in a fuel cell, and then generate electrical energy to supply to the ship or vehicle, etc., to provide power for the ship or vehicle, etc. During the operation of the fuel cell system 100, the air is compressed by the air compressor 2 and passed into the stack 1 for electrochemical reaction to generate electrical energy and drive the load for use; the unreacted air is discharged from the stack 1 and discharged into the atmosphere after passing through the emission and silencer system. The energy in the exhaust gas can also be utilized through a recovery device, and this part of the energy can be converted into electrical energy for use by components, thereby saving energy.

[0048] Specifically, the fuel cell system 100 is provided with a fuel cell stack 1, which is the core component of the fuel cell system 100 and is the place where hydrogen and oxygen undergo electrochemical reactions. The fuel cell stack 1 is connected to a gas supply pipeline 15 and a recovery pipeline. The gas supply pipeline 15 is connected to an air compressor 2. The air compressor 2 can provide air of a suitable metering ratio to the cathode of the fuel cell stack 1 through the gas supply pipeline 15 to enable the fuel cell stack 1 to react. The fuel cell system 100 is also provided with an expander 3. The recovery pipeline is connected to the expander 3. The fuel cell stack 1 can transport air to the expander 3 through the recovery pipeline, thereby driving the turbine of the expander 3 to rotate. The turbine of the expander 3 is connected to an electric motor, so that when the turbine rotates, it can drive the motor to rotate, thereby enabling the motor to generate electrical energy, and the expander 3 is selectively connected to the fuel cell stack 1 through the recovery pipeline. The fuel cell system 100 is also provided with a DCDC module 4, which is a device that converts electric energy of one voltage value into electric energy of another voltage value in a DC circuit. When the expander 3 meets the power supply condition, the DCDC module 4 can be electrically connected to the expander 3, and the DCDC module 4 and the expander 3 can be connected to the grid, so that the DCDC module 4 converts the electric energy generated by the motor connected to the expander 3 into electric energy available to low-voltage accessories, and then supplies power to the low-voltage accessories, such as cooling fans or water pumps.

[0049] Furthermore, the air compressor 2 provides air of a suitable metering ratio to the cathode of the fuel cell stack 1 through the air supply pipeline 15. At the same time, the fuel cell system 100 is provided with a hydrogen medium-pressure pipeline 17, and the hydrogen medium-pressure pipeline 17 is provided with a hydrogen pressure regulating valve 11. The hydrogen pressure regulating valve 11 can control the pressure value of the hydrogen at the anode inlet of the fuel cell stack 1. Under normal circumstances, the electronic control unit of the fuel cell system 100 adjusts the opening of the hydrogen pressure regulating valve 11 through the PID controller to ensure the stability of the hydrogen pressure entering the stack. Hydrogen can enter the fuel cell stack 1 through the hydrogen medium-pressure pipeline 17 and react electrochemically with oxygen in the fuel cell stack 1. The exhaust gas after the reaction of the fuel cell stack 1 can be transported to the expander 3 through the recovery pipeline, and generates electrical energy after the action of the expander 3. When the expander 3 meets the power supply conditions, the DCDC module 4 is electrically connected to the expander 3 and connected to the grid with the expander 3 for power supply, thereby supplying power to the remaining components.

[0050] According to the fuel cell system 100 of the embodiment of the present invention, the fuel cell system 100 can recover the energy of the exhaust gas through the recovery pipeline, thereby achieving efficient operation. At the same time, by setting the DCDC module 4, the recovered energy can stably supply energy to the load without affecting the efficient operation of the fuel cell system 100, thereby achieving energy reuse, saving use costs, better use effects, and a wider range of applications.

[0051] In some embodiments, the expander 3 is connected to the air compressor 2 , and the expander 3 is configured to be non-coaxial with the air compressor 2 .

[0052] Specifically, after the air compressor 2 is powered on and operated, it can provide air of a suitable metering ratio to the cathode of the fuel cell stack 1 through the gas supply pipeline 15. The expander 3 can operate to generate electricity after the gas is introduced through the recovery pipeline. The expander 3 is connected to the air compressor 2. When the expander 3 operates to generate sufficient electricity, the electricity can supply power to the air compressor 2, and the expander 3 is configured to be non-coaxial with the air compressor 2. The expander 3 is configured to be non-coaxial with the air compressor 2 to avoid the situation where the electricity generated by the expander 3 does not meet the electricity required for the normal operation of the air compressor 2 when the expander 3 is operating, thereby increasing the energy consumption of the air compressor 2, and thus avoiding the uncontrollability of the energy of the fuel cell system 100 under different working conditions due to coaxiality.

[0053] In some embodiments, the recovery pipeline includes a main path 141, a first branch 142 and a second branch 143. The main path 141 is connected to the fuel cell stack 1, the first branch 142 and the second branch 143 are selectively connected to the main path 141 respectively, the first branch 142 is connected to the expander 3, and the second branch 143 is suitable for being connected to the external atmosphere.

[0054] Specifically, Figure 1As shown, the recovery pipeline is provided with a main path 141, a first branch 142 and a second branch 143. One end of the main path 141 is connected to the fuel cell stack 1, and the other end is connected to the first branch 142 and the second branch 143 respectively, and the main path 141 is selectively connected to the first branch 142 and the second branch 143, that is, the main path 141 can be connected to the first branch 142 or the second branch 143, one end of the first branch 142 is connected to the main path 141, and the other end is connected to the expander 3. The excess gas after the reaction of the fuel cell stack 1 can be discharged through the main path 141 connected to the fuel cell stack 1. 1 is passed into the recovery pipeline, and when the main path 141 is connected with the first branch 142, the gas can be transported to the expander 3 through the first branch 142, and generate electricity after the expansion machine 3 acts. One end of the second branch 143 is connected to the main path 141, and the other end is connected to the external atmosphere. When the excess gas after the reaction of the fuel cell stack 1 can be passed into the recovery pipeline through the main path 141 connected to the fuel cell stack 1, and when the main path 141 is connected with the second branch 143, the gas can be transported to the external atmosphere through the second branch 143, which can meet more than 100 usage requirements of the fuel cell system.

[0055] In some embodiments, a recovery valve 5 is provided in the recovery pipeline, and the recovery valve 5 is provided with an inlet 51, a first outlet 52 and a second outlet 53. The inlet 51 is connected to the main road 141, the first outlet 52 is connected to the first branch 142, and the second outlet 53 is connected to the second branch 143. The inlet 51 is suitable for selectively connecting to the first outlet 52 or the second outlet 53.

[0056] Specifically, Figure 1 As shown, the fuel cell system 100 is provided with a recovery pipeline connected to the battery stack 1, the recovery pipeline is provided with a main path 141, and a recovery valve 5 is provided in the recovery pipeline, one end of the main path 141 is connected to the battery stack 1, and the other end is connected to the recovery valve 5, the recovery valve 5 is used to control the airflow discharge or perform energy recovery by adjusting the opening of the valve, and the recovery valve 5 is provided with an inlet 51, a first outlet 52 and a second outlet 53, the inlet 51 is connected to the main path 141, so that the gas in the battery stack 1 can flow to the inlet 51 through the main path 141, and the first outlet 52 is connected to the first branch 142, that is, the gas can flow through the first outlet 52 The gas enters the first branch 142, and the second outlet 53 is connected to the second branch 143, that is, the gas can enter the second branch 143 through the second outlet 53, and the inlet 51 is suitable for selectively connecting with the first outlet 52 or the second outlet 53, that is, when a certain condition is met, the inlet 51 is connected to the first outlet 52, and when another condition is met, the inlet 51 is connected to the second outlet 53, so that the gas in the main path 141 flows to the first outlet 52 or the second outlet 53 through the inlet 51 when different conditions are met, and then flows to the first branch 142 through the first outlet 52, or flows to the second branch 143 through the second outlet 53.

[0057] Among them, when the fuel cell system 100 stops running or the gas is insufficient to supply the expander 3, the inlet 51 is connected to the second outlet 53, so that the gas is discharged into the atmosphere. When the gas flowing in the main path 141 of the fuel cell stack 1 is supplied to the expander 3, the inlet 51 is connected to the first outlet 52, so that gas is supplied to the expander 3.

[0058] In some embodiments, Figure 1 As shown, a back-pressure valve 6 is provided in the main path 141. The gas flowing from the battery stack 1 to the main path 141 can flow to the inlet 51 of the recovery valve 5 after passing through the back-pressure valve 6. The back-pressure valve 6 is actuated by the elastic force of a built-in spring. When the pressure at the cathode of the battery stack 1 is smaller than the set pressure, the diaphragm in the back-pressure valve 6 blocks the pipeline under the action of the spring force; when the pressure at the cathode of the battery stack 1 is larger than the set pressure, the diaphragm in the back-pressure valve 6 compresses the spring, the pipeline is connected, and the gas passes through the back-pressure valve 6. The structure of the back-pressure valve 6 is similar to that of the one-way valve, but the opening pressure is greater than that of the one-way valve, which is between 0.2 and 1.6 MPa, so that the back-pressure valve 6 can control the pressure at the cathode of the battery stack 1 by adjusting the opening of its valve. The excess gas after the reaction of the battery stack 1 can be passed into the recovery pipeline through the main path 141 connected to the battery stack 1, thereby controlling the connection between the battery stack 1 and the main path 141.

[0059] In some embodiments, the fuel cell system 100 further includes a bypass branch 16 , which is connected between the gas supply line 15 and the main line 141 , and a bypass valve 7 is disposed in the bypass branch 16 .

[0060] Specifically, Figure 1 As shown, the fuel cell system 100 is also provided with a bypass branch 16, and the bypass branch 16 is connected between the gas supply pipeline 15 and the main road 141, that is, one end of the bypass branch 16 is connected to the gas supply pipeline 15, and the other end is connected to the main road 141. The gas in the gas supply pipeline 15 can flow into the main road 141 through the bypass branch 16. The bypass branch 16 is provided with a bypass valve 7. After the bypass valve 7 is opened, the gas in the gas supply pipeline 15 can directly enter the main road 141 through the bypass branch 16, and then selectively enter the first outlet 52 and the second outlet 53 through the inlet 51 of the recovery valve 5, so as to enter the first branch 142 through the first outlet 52, or enter the second branch 143 through the second outlet 53, so that the gas does not enter the fuel cell stack 1, thereby realizing multiple flow paths of the fuel cell system 100.

[0061] In some embodiments, an intercooler 8 and a humidifier 9 are provided in the gas supply pipeline 15 , and a shut-off valve 10 is provided in the gas supply pipeline 15 between the humidifier 9 and the fuel cell stack 1 .

[0062] Specifically, Figure 1As shown, an intercooler 8 and a humidifier 9 are provided in the gas supply pipeline 15. The intercooler 8 is used to reduce the temperature of the high-temperature air after supercharging and increase the air intake. The humidifier 9 is used to humidify the dry air to ensure the water content of the gas introduced into the fuel cell stack 1. A stop valve 10 is provided between the humidifier 9 and the fuel cell stack 1 in the gas supply pipeline 15. After the stop valve 10 is opened, the gas in the gas supply pipeline 15 can enter the cathode of the fuel cell stack 1 and react chemically with the hydrogen introduced from the hydrogen medium-pressure pipeline 17 to generate electrical energy. A gas-water separator 13 is also provided in the fuel cell system 100. The gas-water separator 13 can separate the gas and liquid water at the anode outlet of the fuel cell stack 1 through the centrifugal principle. The gas-water separator 13 is connected to the external atmosphere through a pipeline, and a nitrogen exhaust and water discharge valve 12 is provided in the pipeline. The nitrogen exhaust and water discharge valve 12 can discharge the nitrogen at the anode of the fuel cell stack 1 and the liquid water in the gas-water separator 13 to the outside.

[0063] The present invention also provides a control method for the fuel cell system 100 .

[0064] According to the control method of the fuel cell system 100 of the embodiment of the present invention, Figure 2 As shown, including:

[0065] A100, obtaining the operating status of the fuel cell system 100;

[0066] A200, when the operating state meets the set operating conditions, the recovery pipeline is controlled to be connected and the expander 3 is started and operated;

[0067] A300, obtaining the voltage state of the expander 3;

[0068] A400, when the voltage state meets the set voltage condition, control the DCDC module 4 to connect to the grid for power supply.

[0069] Specifically, the fuel cell system 100 is started and the air compressor 2 operates normally. At this time, the fuel cell system 100 will enter a stable operation stage, and the operating status of the fuel cell system 100 at this time is obtained. When the fuel cell system 100 is running, the excess gas after the reaction of the battery stack 1 will flow to the back pressure valve 6 through the recovery pipeline. When the gas pressure meets the pressure required for the back pressure valve 6 to open, the back pressure valve 6 opens, and the gas flows to the recovery valve 5 through the main path 141. When the gas pressure meets the opening condition of the first outlet 52, the first outlet 52 is connected to the first branch 142, and then the expander 3 is started to run. When the expander 3 is running, it will generate electrical energy, and the voltage state of the expander 3 during operation is obtained. When the voltage state meets the set voltage condition, the DCDC module 4 is connected to the grid for power supply, and then power is supplied to the remaining components.

[0070] According to the control method of the fuel cell system 100 of the embodiment of the present invention, the control method of the fuel cell system 100 is applied to the fuel cell system 100, so that the fuel cell system 100 can achieve efficient operation and can effectively recover energy from the exhaust gas generated by it. At the same time, by setting the DCDC module 4, the recovered energy can stably supply energy to the load without affecting the efficient operation of the fuel cell system 100, thereby realizing energy reuse, saving use costs, and having better use effects and a wider range of applications.

[0071] In some embodiments, Figure 3 As shown, when the operating state meets the set operating conditions, it includes:

[0072] A210, obtaining an operation stability value of the fuel cell system 100;

[0073] A220, when the running stability value is greater than the set stability value, it is determined that the running state meets the set running conditions;

[0074] and / or, if Figure 4 As shown, when the voltage state meets the set voltage condition, it includes:

[0075] A410, obtaining the output voltage of the expander 3;

[0076] A420: When the output voltage is greater than the set voltage, it is determined that the voltage state meets the set voltage condition.

[0077] Specifically, the fuel cell system 100 is started and the air compressor 2 operates normally. At this time, the fuel cell system 100 will enter a stable operation stage. When the fuel cell system 100 operates stably, its stack 1 will produce electric energy. The electrical density of the electric energy is the operating stability value of the fuel cell system 100 at this time, and the fuel cell system 100 is also provided with a set stability value. When the operating stability value is greater than the set stability value, it can be determined that the operating state meets the set operating conditions, and then the recovery pipeline is controlled to be connected.

[0078] Furthermore, when the recovery pipeline is connected to the fuel cell stack 1, the gas in the fuel cell stack 1 is passed into the main path 141, and when the gas pressure meets the opening condition of the first outlet 52, the first outlet 52 is connected to the first branch 142, the gas is passed into the first branch 142, and the expander 3 is operated to generate a voltage, and the expander 3 can output the voltage to the outside. When the output voltage is greater than the set voltage, it is determined that the voltage state meets the set voltage condition, and the DCDC module 4 can be controlled to supply power to the grid.

[0079] Among them, the set stability value is set according to the stable operating conditions of the equipment equipped with the fuel cell system 100, and the set voltage is the voltage value of the electric energy generated by the motor connected to the expander 3 through the gas recovered through the first branch 142 of the expander when the fuel cell system 100 reaches the set stability value.

[0080] In some embodiments, Figure 5 As shown, the control method of the fuel cell system 100 further includes:

[0081] A500, obtaining the operating status of the fuel cell system 100;

[0082] A600, when shutdown or failure occurs in the running state, the recovery pipeline is controlled to be disconnected to stop the operation of the expander 3, and the grid-connected power supply of the DCDC module 4 is cut off.

[0083] Specifically, the fuel cell system 100 is started, the fuel cell system 100 enters the operation stage, and the operation status of the fuel cell system 100 can be obtained. When the operation status of the fuel cell system 100 is shut down or fails, the recovery pipeline is controlled to be disconnected to stop the expansion machine 3, and the grid power supply of the DCDC module 4 is cut off to protect the fuel cell system 100, avoid leakage of hydrogen, etc., and improve safety performance.

[0084] Reference below Figure 6 As shown, control methods of the fuel cell system 100 according to some specific embodiments of the present invention and implementation steps of the control methods of the fuel cell system 100 are described.

[0085] like Figure 6 As shown, the control method of the fuel cell system 100 has the following specific steps:

[0086] The fuel cell system 100 is started, and the air compressor 2 operates normally. At this time, the fuel cell system 100 will enter the stable operation stage, and the operating status of the fuel cell system 100 at this time is obtained. When the fuel cell system 100 is operating stably, its stack 1 will produce electric energy. The electric density value of the electric energy is the operating stability value of the fuel cell system 100 at this time, and the fuel cell system 100 is also provided with a set stability value, which can be set to 0.2A / cm2. When the operating stability value is less than the set stability value, the air compressor 2 continues to operate, increasing the air supplied to the stack 1, so that the stack 1 continues to react, and then the operating stability value is greater than the set stability value. At this time, it can be determined that the operating status meets the set operating conditions, and then the recovery pipeline is controlled to be connected. The excess gas after the reaction of the stack 1 will pass through the recovery pipeline. Flows to the back pressure valve 6. When the gas pressure meets the pressure required for the back pressure valve 6 to open, the back pressure valve 6 opens, and the gas flows to the recovery valve 5 through the main path 141. When the gas pressure meets the opening condition of the first outlet 52, the first outlet 52 is connected to the first branch 142, and then the expander 3 starts to run. When the expander 3 is running, it will generate electric energy. The voltage state of the expander 3 when it is running is obtained. The fuel cell system 100 is provided with a set voltage, and the set voltage can be set to 24V. When the voltage during operation is greater than the set voltage, the DCDC module 4 is connected to the grid for power supply, and then power is supplied to other components. Otherwise, the DCDC module 4 is stopped from being connected to the grid for power supply. When the system is shut down or fails, the recovery valve 5 is closed, and the grid-connected power supply of the DCDC module 4 is cut off. Otherwise, the DCDC module 4 continues to be connected to the grid for power supply.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0088] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A fuel cell system, characterized in that: include: A fuel cell stack, wherein the fuel cell stack is connected to an air compressor via an air supply pipeline; an expander, the expander being selectively connected to the fuel cell stack via a recovery pipeline; A DCDC module is connected to the fuel cell stack, and is suitable for being electrically connected to the expander and performing grid-connected power supply when the expander meets power supply conditions.

2. The fuel cell system according to claim 1, characterized in that: The expander is connected to the air compressor, and the expander is configured to be non-coaxial with the air compressor.

3. The fuel cell system according to claim 1, characterized in that: The recovery pipeline includes a main circuit, a first branch circuit and a second branch circuit. The main circuit is connected to the fuel cell stack. The first branch circuit and the second branch circuit are selectively connected to the main circuit respectively. The first branch circuit is connected to the expander. The second branch circuit is suitable for connecting to the external atmosphere.

4. The fuel cell system according to claim 3, characterized in that: A recovery valve is provided in the recovery pipeline, and the recovery valve is provided with an inlet, a first outlet and a second outlet. The inlet is connected to the main road, the first outlet is connected to the first branch, and the second outlet is connected to the second branch. The inlet is suitable for selectively connecting to the first outlet or the second outlet.

5. The fuel cell system according to claim 3, characterized in that: A back pressure valve is arranged in the main path.

6. The fuel cell system according to claim 3, characterized in that: It also includes a bypass branch, which is connected between the air supply pipeline and the main pipeline, and a bypass valve is provided in the bypass branch.

7. The fuel cell system according to claim 1, characterized in that: An intercooler and a humidifier are provided in the air supply pipeline, and a stop valve is provided between the humidifier and the fuel cell stack.

8. A control method for a fuel cell system, characterized in that: include: Obtaining the operating status of the fuel cell system; When the operating state meets the set operating conditions, the recovery pipeline is controlled to be connected and the expander is started to operate; obtaining a voltage state of the expander; When the voltage state meets the set voltage condition, the DCDC module is controlled to connect to the grid for power supply.

9. The control method of the fuel cell system according to claim 8, characterized in that: When the operating state meets the set operating conditions, the following steps are included: Obtaining an operational stability value of the fuel cell system; When the operation stability value is greater than the set stability value, determining that the operation state meets the set operation condition; And / or, when the voltage state satisfies a set voltage condition, the method includes: obtaining an output voltage of the expander; When the output voltage is greater than the set voltage, it is determined that the voltage state satisfies the set voltage condition.

10. The control method of the fuel cell system according to claim 8, characterized in that: Also includes: Obtaining the operating status of the fuel cell system; When shutdown or failure occurs in the operating state, the recovery pipeline is controlled to be disconnected so that the expander stops running, and the grid-connected power supply of the DCDC module is cut off.

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