A fuel cell system and control method

Abstract

This invention provides a fuel cell system and control method. Compared to existing fuel cell systems, this system adds a first diode module and a relay module. Controlling the relay module to be in a closed or open state controls the electrical circuit of the fuel cell system. When the relay module is closed, the power battery supplies power to the air compressor module, enabling the air compressor module to operate and providing air to the fuel cell system, thus putting the fuel cell stack into operation. When the relay module is open, unlike existing systems where the fuel cell stack supplies power to the air compressor module via a DC / DC converter, in this system, the fuel cell stack directly supplies power to the air compressor module via the first diode module. This direct power supply from the fuel cell stack reduces power loss to the air compressor module and improves the efficiency of the fuel cell system.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically, to a fuel cell system and control method. Background Technology

[0002] In existing fuel cell systems, all high-voltage components are powered through DC / DC converters, which increases the output power of the DC / DC converters. Commonly used DC / DC converters are multi-boost parallel topologies. When the fuel cell system is working, because the conversion efficiency of the DC / DC converter is not 100%, there will be some power loss when supplying power to the high-voltage components.

[0003] In a fuel cell system, high-pressure components mainly include an air compressor (rated power of approximately 20–40 kW), a hydrogen circulation pump (rated power of approximately 1–1.5 kW), and a cooling pump (rated power of approximately 0.5 kW). Since the power consumption of the air compressor is the main part of the power consumption of high-pressure components, reducing the high-pressure power loss of the air compressor can improve the efficiency of the fuel cell system. Therefore, reducing the high-pressure power loss of the air compressor has become an urgent problem to be solved. Summary of the Invention

[0004] In view of this, to solve the above problems, the present invention provides a fuel cell system and a control method, the technical solution of which is as follows:

[0005] A fuel cell system, the fuel cell system comprising:

[0006] Fuel cell stack, first diode module, relay module, air compressor module, and power battery;

[0007] The first end of the fuel cell stack is electrically connected to the first end of the first diode module and the first end of the relay module, respectively; the second end of the first diode module is electrically connected to the first end of the air compressor module; the second end of the relay module is electrically connected to the first end of the air compressor module; the second end of the air compressor module is electrically connected to the first end of the power battery and the second end of the fuel cell stack, respectively; the second end of the power battery is electrically connected to the first end of the relay module.

[0008] The fuel cell stack provides power to the fuel cell system; the first diode module and the relay module control the electrical circuit of the fuel cell system; the power battery provides power to the air compressor module; and the air compressor module provides air to the fuel cell system.

[0009] A control method for a fuel cell system, used to control any of the above-described fuel cell systems, the control method comprising:

[0010] The control relay module is in the closed state, and the control power battery provides working power to the air compressor module, so that the air compressor module is in the working state and provides air to the fuel cell system;

[0011] The control relay module is in the off state, and the control fuel cell stack transmits the output voltage to the air compressor module through the first diode module, so that the air compressor module is in a continuous working state.

[0012] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0013] This invention provides a fuel cell system, comprising a fuel cell stack, a first diode module, a relay module, an air compressor module, and a power battery. A first terminal of the fuel cell stack is electrically connected to both the first terminal of the first diode module and the first terminal of the relay module. A second terminal of the first diode module is electrically connected to the first terminal of the air compressor module. A second terminal of the relay module is electrically connected to the first terminal of the air compressor module. A second terminal of the air compressor module is electrically connected to both the first terminal of the power battery and the second terminal of the fuel cell stack. A second terminal of the power battery is electrically connected to the first terminal of the relay module. The fuel cell stack provides power to the fuel cell system. The first diode module and the relay module control the electrical circuit of the fuel cell system. The power battery provides power to the air compressor module. The air compressor module provides air to the fuel cell system.

[0014] In this fuel cell system, compared to existing fuel cell systems, a first diode module and a relay module are added. Controlling the relay module to be in a closed or open state controls the electrical circuit of the fuel cell system. When the relay module is in a closed state, the power battery and the air compressor module form a circuit, and the power battery supplies power to the air compressor module, enabling the air compressor module to operate and supply air to the fuel cell system, thus enabling the fuel cell stack to operate. At this time, the relay module is in a closed state. Compared to existing fuel cell stacks that supply power to the air compressor module through a DC / DC converter, in this fuel cell system, the fuel cell stack directly supplies power to the air compressor module through the first diode module. Directly using the fuel cell stack to supply power to the air compressor module reduces the power loss of the air compressor module and improves the efficiency of the fuel cell system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of an existing fuel cell system;

[0017] Figure 2 This is a partial structural schematic diagram of a fuel cell system provided in an embodiment of the present invention;

[0018] Figure 3 This is a partial structural schematic diagram of another fuel cell system provided in an embodiment of the present invention;

[0019] Figure 4 A schematic diagram of a fuel cell system provided in an embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of the structure of a DC / DC converter provided in an embodiment of the present invention;

[0021] Figure 6 This is a schematic diagram of the structure of an air compressor module provided in an embodiment of the present invention;

[0022] Figure 7 A schematic flowchart of a control method for a fuel cell system provided in an embodiment of the present invention;

[0023] Figure 8 A schematic diagram of the high-voltage power supply circuit of the air compressor module before operation of the fuel cell system provided in an embodiment of the present invention;

[0024] Figure 9 This is a schematic diagram of the high-voltage power supply circuit of the air compressor module during operation of the fuel cell system provided in an embodiment of the present invention;

[0025] Figure 10 A flowchart illustrating another control method for a fuel cell system provided in an embodiment of the present invention;

[0026] Figure 11 A schematic diagram of the high-voltage circuit for energy braking recovery of the air compressor module during load reduction in a fuel cell system provided in an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Based on the content in the background art, refer to Figure 1 , Figure 1 This is a schematic diagram of an existing fuel cell system. The existing fuel cell system includes a fuel cell 31, a DC / DC converter 32, an air compressor 33, a power battery 34, a high-voltage component module 35, a low-voltage component module 36, and a system controller 37. During system operation, the DC / DC converter 32 simultaneously provides power to the vehicle's power system and all high-voltage components, therefore the DC / DC converter 32 has a relatively large rated power. The high-voltage components include the air compressor 33 and the high-voltage component module 35. Because the conversion efficiency of the DC / DC converter 32 is not 100%, there is a partial system power loss when supplying power to the high-voltage components, and the power consumption of the air compressor 33 is the main component among these high-voltage components.

[0029] In existing fuel cell systems, the voltage output from fuel cell 31 needs to be converted by DC / DC converter 32 before supplying power to air compressor 33. Since the efficiency of DC / DC converter 32 in the voltage conversion process is about 90%, assuming the power of air compressor 33 is 30kW, if fuel cell 31 is used to supply power directly, it would consume 30kW of output energy. However, if the existing fuel cell system uses DC / DC converter 32 for voltage conversion, fuel cell 31 needs to output 33.3kW of energy, which is then converted by DC / DC converter 32 (output power is 33.3 × 90% = 30) to output 30kW in order to ensure the normal operation of air compressor 33, thus consuming an extra 3.3kW of power.

[0030] Therefore, the present invention provides a fuel cell system and control method to solve the above problems. The fuel cell system includes: a fuel cell stack, a first diode module, a relay module, an air compressor module, and a power battery; a first end of the fuel cell stack is electrically connected to a first end of the first diode module and a first end of the relay module; a second end of the first diode module is electrically connected to a first end of the air compressor module; a second end of the relay module is electrically connected to a first end of the air compressor module; a second end of the air compressor module is electrically connected to a first end of the power battery and a second end of the fuel cell stack; a second end of the power battery is electrically connected to a first end of the relay module; the fuel cell stack provides power to the fuel cell system; the first diode module and the relay module control the electrical circuit of the fuel cell system; the power battery provides power to the air compressor module; and the air compressor module provides air to the fuel cell system.

[0031] In this fuel cell system, compared to existing fuel cell systems, a first diode module and a relay module are added. Controlling the relay module to be in a closed or open state controls the electrical circuit of the fuel cell system. When the relay module is in a closed state, the power battery and the air compressor module form a circuit, and the power battery supplies power to the air compressor module, enabling the air compressor module to operate and supply air to the fuel cell system, thus enabling the fuel cell stack to operate. At this time, the relay module is in a closed state. Compared to existing fuel cell stacks that supply power to the air compressor module through a DC / DC converter, in this fuel cell system, the fuel cell stack directly supplies power to the air compressor module through the first diode module. Directly using the fuel cell stack to supply power to the air compressor module reduces the power loss of the air compressor module and improves the efficiency of the fuel cell system.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] refer to Figure 2 , Figure 2 This is a partial structural schematic diagram of a fuel cell system provided in an embodiment of the present invention.

[0034] The fuel cell system includes:

[0035] The fuel cell stack 01, the first diode module 02, the relay module 03, the air compressor module 04, and the power battery 05.

[0036] The first terminal 01a of the fuel cell stack 01 is electrically connected to the first terminal 02a of the first diode module 02 and the first terminal 03a of the relay module 03, respectively; the second terminal 02b of the first diode module 02 is electrically connected to the first terminal 04a of the air compressor module 04; the second terminal 03b of the relay module 03 is electrically connected to the first terminal 04a of the air compressor module 04; the second terminal 04b of the air compressor module 04 is electrically connected to the first terminal 05a of the power battery 05 and the second terminal 01b of the fuel cell stack 01, respectively; the second terminal 05b of the power battery 05 is electrically connected to the first terminal 03a of the relay module 03.

[0037] The fuel cell stack 01 is used to provide power to the fuel cell system; the first diode module 02 and the relay module 03 are used to control the electrical circuit of the fuel cell system; the power battery 05 is used to provide power to the air compressor module 04; the air compressor module 04 is used to provide air to the fuel cell system.

[0038] Specifically, such as Figure 2 As shown, the dashed boxes are only for better illustrating the modules in this fuel cell system, and the areas enclosed by the dashed boxes are only the modules that need to be explained, such as... Figure 2 The first diode module 02 and the relay module 03 are connected to form an electrical circuit by electrically connecting the fuel cell stack 01, the first diode module 02, the relay module 03, the air compressor module 04 and the power battery 05, so that each module can realize its own function.

[0039] It should be noted that the fuel cell electric propulsion unit 01 can also be used to provide power for the power output of the fuel cell system. In other words, part of the electricity output by the fuel cell stack 01 can be used to power the fuel cell system, and another part can be used to power external loads (such as vehicle batteries, drive motors, etc.).

[0040] In this fuel cell system, compared to existing fuel cell systems, a first diode module 02 and a relay module 03 are added. Controlling the relay module 03 to be in a closed or open state controls the electrical circuit of the fuel cell system. When the relay module 03 is in a closed state, the power battery 05 forms a circuit with the air compressor module 04, and the power battery 05 supplies power to the air compressor module 04, putting the air compressor module 04 into operation and providing air to the fuel cell system, thereby putting the fuel cell stack 01 into operation. At this time, the relay module 03 is in a closed state. Compared to existing fuel cell stacks 01 supplying power to the air compressor module 04 through a DC / DC converter, in this fuel cell system, the fuel cell stack 01 directly supplies power to the air compressor module 04 through the first diode module 02. Directly using the fuel cell stack 01 to supply power to the air compressor module 04 reduces the power loss of the air compressor module 04 and improves the efficiency of the fuel cell system.

[0041] Optionally, in another embodiment of the invention, reference is made to... Figure 3 , Figure 3 This is a partial structural schematic diagram of another fuel cell system provided in an embodiment of the present invention; the fuel cell system further includes:

[0042] The second diode module 06 has its first terminal 06a electrically connected to the second terminal 03b of the relay module 03; and its second terminal 06b electrically connected to the second terminal 05b of the power battery 05.

[0043] The second diode module 06 is used to control the electrical circuit of the fuel cell system.

[0044] Specifically, when the relay module 03 is in the off state, the second diode module 06, the air compressor module 04, and the power battery 05 form an electrical circuit. In this fuel cell system, a second diode module 06 is further added compared to the existing fuel cell system and the fuel cell system in the above embodiment. When the fuel cell system is in operation and the power rapidly drops from a high power to a low power state, i.e., the load reduction state, the braking energy generated by the air compressor module 04 in this state will be recovered and stored in the power battery 05 through the second diode module 06.

[0045] Optionally, in another embodiment of the invention, reference is made to... Figure 4 , Figure 4 This is a schematic diagram of a fuel cell system provided in an embodiment of the present invention; the fuel cell system further includes:

[0046] DC / DC converter 07, high voltage component module 08, low voltage component module 09, and system controller 10.

[0047] The first terminal 07a of the DC / DC converter 07 is electrically connected to the first terminal 01a of the fuel cell stack 01; the second terminal 07b of the DC / DC converter 07 is electrically connected to the second terminal 06b of the second diode module 06; the third terminal 07c of the DC / DC converter 07 is electrically connected to the second terminal 01b of the fuel cell stack 01; and the fourth terminal 07d of the DC / DC converter 07 is electrically connected to the second terminal 04b of the air compressor module 04.

[0048] The first terminal 08a of the high-voltage component module 08 is electrically connected to the second terminal 07b of the DC / DC converter 07 and the second terminal 05b of the power battery 05, respectively; the second terminal 08b of the high-voltage component module 08 is electrically connected to the second terminal 04b of the air compressor module 04 and the second terminal 05b of the power battery 05, respectively.

[0049] The third terminal 08c of the high-voltage component module 08 is electrically connected to the first terminal 10a of the system controller 10; the second terminal 10b of the system controller 10 is electrically connected to the third terminal 01c of the fuel cell stack 01; and the third terminal 10c of the system controller 10 is electrically connected to the low-voltage component 09.

[0050] The DC / DC converter 07 is used to convert the voltage output by the fuel cell stack 01 into the voltage required for the operation of the fuel cell system; the system controller 10 is used to control the operating status of the high-voltage component module 08 and the low-voltage component module 09.

[0051] Specifically, the power battery 05 provides power to the air compressor module 04, enabling the air compressor module 04 to operate. The operating air compressor module 04 provides air to the fuel cell system, thereby enabling the fuel cell 01 to operate. At this time, the voltage generated by the fuel cell stack 01 will provide power to the high-voltage component module 08 through the DC / DC converter 07, enabling the high-voltage component module 08 to operate. At the same time, the fuel cell stack 01 provides power to the system controller 10, enabling it to control other devices in the fuel cell system, and also provides power to the low-voltage component module 09 through the system controller 10.

[0052] Optionally, in another embodiment of the present invention, the system control module 10 is further used to control the working state of the relay module 03.

[0053] Specifically, the relay module 03 operates in two states: closed and open. When the relay module 03 is closed, the electrical circuit between the power battery 05 and the air compressor module 04 is connected, and the power battery 05 provides power to the air compressor module 04, thus putting the air compressor module 04 into operation. Furthermore, the air compressor module 04 provides air to the fuel cell stack 01, thus putting the fuel cell stack 01 into operation. When the relay module 03 is open, the voltage generated by the fuel cell stack 01 is transmitted to the air compressor module 04 through the first diode module 02. At this time, the power source for the air compressor module 04 is the fuel cell stack 01. When the fuel cell system is in a deload state, the braking energy generated in the air compressor module 04 is recovered and stored in the power battery 05 through the second diode module 06.

[0054] Optionally, in another embodiment of the invention, reference is made to... Figure 5 , Figure 5 This is a schematic diagram of a DC / DC converter provided in an embodiment of the present invention; the DC / DC converter 07 further includes:

[0055] Multiple control submodules 11; the multiple control submodules 11 are arranged in parallel.

[0056] The control submodule 11 includes a first field-effect transistor 111, a first inductor 112, and a diode 113; the second field-effect transistor 111, the second inductor 112, and the diode 113 are electrically connected.

[0057] Specifically, Figure 5 The connection method of the control submodule 11 is only one. In this embodiment, there are five control submodules 11 connected in parallel. Each control submodule 11 can control the working state of one line. The diode 113 can be an iron core inductor and the first field-effect transistor 111 can be an NMOS field-effect transistor.

[0058] In this control submodule 11, the first terminal 112a of the first inductor 112 is electrically connected to the first terminal 07a of the DC / DC converter 07, the second terminal 112b of the first inductor 112 is electrically connected to the first terminal 113a of the diode 113, the second terminal 113b of the diode 113 is electrically connected to the second terminal 07b of the DC / DC converter 07, the first terminal 111a of the first field-effect transistor 111 is electrically connected to the second terminal 112b of the first inductor 112, and the second terminal 111b of the first field-effect transistor 111 is electrically connected to the third terminal 07c of the DC / DC converter 07.

[0059] It should be noted that, compared to the six parallel control sub-modules in existing DC / DC converters, this invention simplifies the structure of the DC / DC converter 07 in the fuel cell system and reduces the cost of the fuel cell system.

[0060] Optionally, in another embodiment of the invention, reference is made to... Figure 6 , Figure 6 This is a schematic diagram of the structure of an air compressor module provided in an embodiment of the present invention; the air compressor module 04 includes:

[0061] Power device submodule 12; the power device submodule 12 includes a plurality of second field-effect transistors 121, a plurality of second inductors 122 and a motor 123; the second field-effect transistors 121, the second inductors 122 and the motor 123 are electrically connected; the power device submodule 12 is used to control the power output of the air compressor module 04.

[0062] Specifically, Figure 6 The device includes six second field-effect transistors 121, three second inductors 122, and a motor 123. The second field-effect transistors 121 can be NMOS field-effect transistors. In this power device submodule 12, two second field-effect transistors 121 in the first region 121a are connected in series to form a series structure, and the source of the first second field-effect transistor 121 is electrically connected to the drain of the second second field-effect transistor 121. Two second field-effect transistors 121 in the second region 112b are connected in series to form a series structure, and the source of the third second field-effect transistor 121 is connected to the drain of the fourth second field-effect transistor 122. The drain of the second field-effect transistor 121 in the third region 112c is connected in series to form a series structure, and the source of the fifth second field-effect transistor 121 is connected to the drain of the sixth second field-effect transistor 121; the series structures of the first region 121a, the second region 112b and the third region 112c are arranged in parallel; the floating drain of the second field-effect transistor 121 in each region is connected to the first terminal 04a of the air compressor module 04, and the floating source of the second field-effect transistor 121 in each region is connected to the second terminal 04b of the air compressor module 04.

[0063] Furthermore, one end of each of the three second inductors 122 is electrically connected to the motor 123, and the other end of each of the three second inductors 122 is connected to the source of the first second field-effect transistor 121 in the first region 121a, the source of the third second field-effect transistor 121 in the second region 121b, and the source of the fifth second field-effect transistor 121 in the third region 121c.

[0064] Based on the fuel cell system in the above embodiments, the present invention also provides a control method for a fuel cell system, which is used to control the fuel cell system described in the above embodiments. The control method will be described below.

[0065] Optionally, in another embodiment of the invention, reference is made to... Figure 7 , Figure 7This is a flowchart illustrating a control method for a fuel cell system provided in an embodiment of the present invention; the control method includes:

[0066] S101: Control relay module 03 to be in the closed state, and control power battery 05 to provide working power to air compressor module 03, so that air compressor module 04 is in working state and provides air to the fuel cell system.

[0067] In this step, refer to Figure 8 , Figure 8 This is a schematic diagram of the high-voltage power supply circuit of the air compressor module before operation in an embodiment of the present invention; as shown. Figure 8 As shown, before the fuel cell system starts working, the control relay module 03 is in the closed state. At this time, the system controller 10 controls the relay module 03 to close its contacts. The power battery 05 and the air compressor module 04 form a high-voltage power supply circuit through circuit ① and circuit ②. The power battery 05 provides high-voltage power to the air compressor module 04, supporting the air compressor module 04 to be in working state. After the air compressor module 04 starts working, it provides air supply for the fuel cell system to start, thereby ensuring the normal operation of the fuel cell system.

[0068] S102: Control the relay module 03 to be in the off state, and control the fuel cell stack 01 to transmit the output voltage to the air compressor module 04 through the first diode module 02, so that the air compressor module 04 is in a continuous working state.

[0069] In this step, because the air compressor module 04 provides air to the fuel cell system in step S101, the fuel cell stack 01 is in an operational state; (Refer to...) Figure 9 , Figure 9 This is a schematic diagram of the high-voltage power supply circuit of the air compressor module during operation of the fuel cell system provided in an embodiment of the present invention; as shown. Figure 9 As shown, after the fuel cell stack 01 is in the working state, the control relay module 03 is in the open state. At this time, the system controller 10 controls the relay module 03 to open the contacts. The fuel cell stack 01, the first diode module 02 and the air compressor module 04 form a high-voltage power supply circuit through circuit ③ and circuit ④. The fuel cell stack 01 transmits the generated voltage directly to the air compressor module 04 through the first diode module 02, so that the air compressor module 04 is in a continuous working state.

[0070] It should be noted that since the power of the air compressor module 04 is the power consumption of the internal components of the fuel cell system, under the same output power of the fuel cell stack 01, this high-voltage power supply circuit reduces the power loss of the internal components of the system, which is equivalent to increasing the output power of the fuel cell system, and thus indirectly improving the efficiency of the fuel cell system.

[0071] Optionally, in another embodiment of the invention, reference is made to... Figure 10 , Figure 10 This is a flowchart illustrating another control method for a fuel cell system provided in an embodiment of the present invention; the control method further includes:

[0072] S103: When a load reduction occurs during the operation of the fuel cell system, the relay module 03 is controlled to be in the open state, and the braking energy in the air compressor module 04 is controlled to be transmitted to the power battery 05 through the second diode module 06.

[0073] In this step, based on steps S101 and S102 above, the fuel cell system begins to operate normally. When a load reduction occurs during the operation of the fuel cell system, that is, when the fuel cell system rapidly drops from a high power (corresponding to a high operating speed of the air compressor module 04) to a low power (corresponding to a low operating speed of the air compressor module 04), refer to... Figure 11 , Figure 11 This is a schematic diagram of the high-voltage circuit for energy recovery braking of the air compressor module during load reduction in a fuel cell system provided in an embodiment of the present invention. The control relay module 03 is in the open state. At this time, the system controller 10 controls the relay module 03 to open its contacts. The air compressor module 04, the second diode module 06, and the power battery 05 form a high-voltage recovery circuit through circuit ⑤ and circuit ⑥. The braking energy generated in the air compressor module 04 will be recovered and stored in the power battery 05 through the second diode module 06.

[0074] It should be noted that, based on the control method of this fuel cell system, the present invention also designs a control algorithm for the air compressor module 04. In this design, since the air compressor module 04 includes multiple power device sub-modules 12, which are power devices of the DC / AC inverter circuit, considering the losses of the multiple power device sub-modules 12 in the air compressor module 04 (mainly conduction losses and switching losses), the switching frequency of the power devices of the DC / AC inverter circuit is dynamically adjusted according to the output power state of the fuel cell system to reduce the switching losses of the power device sub-modules 12, thereby reducing the overall power consumption of the air compressor module 04. This design method improves the output efficiency of the fuel cell system by adjusting and optimizing the control drive algorithm of the power device modules of the DC / AC inverter circuit inside the air compressor module 04.

[0075] It should be noted that, in order to ensure the normal operation of the fuel cell system, the present invention also designs the power supply voltage range of the air compressor module 04. In this design, considering that the output voltage of the fuel cell stack 01 is the highest when the electrical density is low (denoted as UFH) and the output voltage is the lowest when the rated power output is at the end of the life of the fuel cell stack 01 (denoted as UFL), the high voltage power supply range of the air compressor module 04 should cover the voltage range of UFL to UFH (the lowest output voltage to the highest output voltage), and the power supply of the air compressor module 04 can meet the rated power output when the voltage is UFH.

[0076] In this fuel cell system, compared to existing fuel cell systems, a first diode module 02, a relay module 03, and a second diode module 06 are added. The first diode module 02, relay module 03, and second diode module 06 are used to control and automatically switch the high-voltage power supply circuit of the air compressor module 04 before the fuel cell system starts working, during normal operation, and during load reduction. The use of the first diode module 02 allows the power supply of the air compressor module 04 to be directly provided by the fuel cell stack 01, resulting in a reduction in the rated power of the DC / DC converter 07. At the same time, it eliminates the power loss caused by the conversion efficiency problem when the DC / DC converter 07 supplies power to the air compressor module 04 in existing fuel cell systems, reducing the cost of the DC / DC converter 07 while improving the efficiency of the fuel cell system.

[0077] The present invention has provided a detailed description of a fuel cell system and control method. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0078] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0079] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that elements inherent to a process, method, article, or apparatus that comprises a list of elements, or elements inherent to such processes, methods, articles, or apparatus, are also included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0080] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fuel cell system, characterized in that, The fuel cell system includes: Fuel cell stack, first diode module, relay module, air compressor module, and power battery; The first end of the fuel cell stack is electrically connected to the first end of the first diode module and the first end of the relay module, respectively; the second end of the first diode module is electrically connected to the first end of the air compressor module; the second end of the relay module is electrically connected to the first end of the air compressor module; the second end of the air compressor module is electrically connected to the first end of the power battery and the second end of the fuel cell stack, respectively; the second end of the power battery is electrically connected to the first end of the relay module. The fuel cell stack provides power to the fuel cell system; the first diode module and the relay module control the electrical circuit of the fuel cell system; wherein, the relay module is in a closed or open state, and the fuel cell stack directly supplies power to the air compressor module through the first diode module when the relay module is in the open state; the power battery provides power to the air compressor module when the relay module is in the closed state; the air compressor module provides air to the fuel cell system; The second diode module has a first terminal electrically connected to the second terminal of the relay module; the second terminal of the second diode module is electrically connected to the second terminal of the power battery; when the relay module is in the off state, the second diode module forms an electrical circuit with the air compressor module and the power battery. The second diode module is used to control the electrical circuit of the fuel cell system.

2. The fuel cell system according to claim 1, characterized in that, The fuel cell system also includes: DC / DC converters, high-voltage component modules, low-voltage component modules, and system controllers; The first terminal of the DC / DC converter is electrically connected to the first terminal of the fuel cell stack; the second terminal of the DC / DC converter is electrically connected to the second terminal of the second diode module; the third terminal of the DC / DC converter is electrically connected to the second terminal of the fuel cell stack; and the fourth terminal of the DC / DC converter is electrically connected to the second terminal of the air compressor module. The first end of the high-voltage component module is electrically connected to the second end of the DC / DC converter and the second end of the power battery, respectively; the second end of the high-voltage component module is electrically connected to the second end of the air compressor module and the second end of the power battery, respectively. The third terminal of the high-voltage component module is electrically connected to the first terminal of the system controller; the second terminal of the system controller is electrically connected to the third terminal of the fuel cell stack; the third terminal of the system controller is electrically connected to the low-voltage component. The DC / DC converter is used to convert the voltage output by the fuel cell stack into the voltage required for the operation of the fuel cell system; the system controller is used to control the operating status of the high-voltage component module and the low-voltage component module.

3. The fuel cell system according to claim 2, characterized in that, The system controller is also used to control the operating status of the relay module.

4. The fuel cell system according to claim 2, characterized in that, The DC / DC converter also includes: Multiple control submodules; the multiple control submodules are configured in parallel; The control submodule includes a first field-effect transistor, a first inductor, and a diode; the first field-effect transistor, the first inductor, and the diode are electrically connected.

5. The fuel cell system according to claim 1, characterized in that, The air compressor module includes: A power device submodule; the power device submodule includes multiple second field-effect transistors, multiple second inductors, and a motor; the second field-effect transistors, the second inductors, and the motor are electrically connected; the power device submodule is used to control the power output of the air compressor module.

6. A control method for a fuel cell system, used to control the fuel cell system according to any one of claims 1-5, characterized in that, The control method includes: The control relay module is in the closed state, and the control power battery provides working power to the air compressor module, so that the air compressor module is in the working state and provides air to the fuel cell system; The control relay module is in the off state, and the control fuel cell stack transmits the output voltage to the air compressor module through the first diode module, so that the air compressor module is in a continuous working state; When a load reduction occurs during the operation of the fuel cell system, the relay module is controlled to be in the open state, and the braking energy in the air compressor module is controlled to be transmitted to the power battery through the second diode module.

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