WO2023178946A1

WO2023178946A1 - Fuel cell system and control method therefor

Info

Publication number: WO2023178946A1
Application number: PCT/CN2022/119510
Authority: WO
Inventors: 邓佳; 刘小青; 梁未栋
Original assignee: 中山大洋电机股份有限公司
Priority date: 2022-03-23
Filing date: 2022-09-19
Publication date: 2023-09-28
Also published as: CN114388843B; CN114388843A

Abstract

Disclosed in the present invention are a fuel cell system and a control method therefor. The fuel cell system comprises a fuel cell stack module, a hydrogen supply system, an air supply system, and a cooling system, the cooling system comprising a water pump which drives a coolant to continuously flow to take away heat; and the fuel cell system is characterized in that the water pump is a water pump integrated with an expander, and comprises the expander, a water pump body, a water pump electric motor and a water pump controller, wherein the water pump controller controls the water pump electric motor to operate; the expander is coupled to one end of a rotating shaft of the water pump electric motor, and the other end of the rotating shaft of the water pump electric motor is coupled to the water pump body; and an exhaust tail gas resulting from an reaction is discharged using the fuel cell stack module, and is then input into the expander, the expander does work to drive the water pump body to operate, so as to provide power for the coolant of the cooling system to flow. The structural arrangement of the fuel cell system is rational and simple, the energy recovery problem of the exhaust tail gas of the fuel cell system is effectively solved, the utilization rate is high, and the efficiency of the fuel cell system is effectively improved.

Description

A fuel cell system and control method

Technical field

The invention relates to a fuel cell system and a control method.

Background technique

A fuel cell is an energy conversion device that generates electrical energy through the electrochemical reaction of hydrogen and oxygen. It has the advantages of high energy conversion efficiency, simple structure, low noise, and no pollution. Fuel cells usually work at higher operating pressures, that is, the air entering the stack needs to be compressed to a certain pressure, and the oxygen in it reacts electrochemically with the hydrogen in the anode of the stack to produce electricity, water and heat. The front fuel cell generally discharges the reacted gas directly through the tail exhaust without any treatment to the tail exhaust. However, the exhaust gas discharged after the reaction still has a high pressure. This part of the gas with a pressure and temperature higher than that of the atmosphere carries high energy, resulting in a low energy efficiency utilization rate of the fuel cell system.

In order to solve the above problems, some air compressors with turbo expanders are also used. The energy in the exhaust gas is recovered through the turbo expander, reducing the power consumption of the air compressor, thereby improving the efficiency of the fuel cell system.

In the existing technology, some technical solutions are to use the tail exhaust gas to be input into an expander and then drive the air compressor. The turbo expander is usually coaxially designed to be integrated with the air compressor, and the air compressor is a single-pole centrifugal type. Centrifugal air compressors usually use air bearings. After integrating the expander, it will cause some interference to the stability of the air bearings. As the power of the fuel cell system increases, the requirements for air pressure and flow are getting higher and higher. Currently, bipolar centrifugal air compressors are commonly used. The two-stage air compressor pump heads are located on both sides of the air compressor motor. On the other hand, the integration of the expander will be very complicated and difficult, and will result in certain performance deficiencies.

Contents of the invention

The purpose of the present invention is to provide a fuel cell system and a control method that can solve the problem in the prior art that the exhaust gas discharged from the stack module of the fuel cell is input to the expander, and the expander is coupled to the air compressor, but due to the air compression The technical requirements of the machine itself are high. The drive motor of the existing air compressor has a double shaft extension to connect the load. The technical difficulty of integrating the expander is high, resulting in certain technical problems such as insufficient performance and low energy efficiency utilization.

The purpose of the present invention is achieved through the following technical solutions:

A fuel cell system includes a stack module, a hydrogen supply system, an air supply system and a cooling system. The cooling system includes a water pump. The water pump drives the coolant to continuously flow to take away heat. The water pump is an integrated expander. The water pump includes an expander, a water pump body, a water pump motor and a water pump controller. The water pump controller controls the work of the water pump motor. The expander is coupled to one end of the rotating shaft of the water pump motor, and the other end of the rotating shaft of the water pump motor is coupled to the water pump body. The reacted exhaust gas discharged from the stack module is input to the expander, and the work of the expander drives the water pump body to operate, providing power for the flow of coolant in the cooling system.

The output end of the above-mentioned stack module is electrically connected to the high-voltage power platform through a DC-DC boost converter. The electric energy output by the stack module is processed by the DC-DC boost converter and then stored in the high-voltage power platform.

The above-mentioned water pump motor is an all-in-one machine that integrates the functions of a motor and a generator. The water pump motor is electrically connected to the battery through a high-voltage busbar. The electric energy provided by the battery passes through the water pump controller to make the water pump motor drive the water pump body to work, or the expander drives the water pump. It works as a whole, or the expander charges the battery through the water pump motor and water pump controller to achieve energy recovery.

The above-mentioned expander is coaxially arranged with the water pump body and arranged at both ends of the water pump motor.

The above-mentioned expander adopts a turbine expander.

The above-mentioned DC input source of the water pump controller is connected to the battery high-voltage bus.

The above-mentioned water pump body includes a pump casing. A pump chamber is set inside the pump casing. An impeller is installed in the pump chamber. A water inlet and a water outlet are provided on the pump casing to communicate with the pump chamber. The impeller is installed on the other end of the rotating shaft of the water pump motor.

The output power of the above-mentioned expander is P1, and the output power of the water pump body is P2. The water pump controller controls the operation of the water pump motor according to the output power of P1 and the output power of the water pump body of P2.

When the output power P1 of the expander is less than the output power P2 of the water pump body, the battery outputs electric energy to drive the water pump motor to compensate for the power difference between P1 and P2; when the output power P1 of the expander is equal to the output power P2 of the water pump body, The expander provides all the power required by the water pump body; when the output power P1 of the expander is greater than the output power P2 of the water pump body, the expander not only provides the power required by the water pump body, but also drives the water pump motor to generate electricity and recover the system energy. Utilized and transmitted to the high voltage bus.

The above-mentioned water pump controller contains the set working speed V1 of the water pump body. The set working speed V1 of the water pump body is determined according to the requirements of the cooling system. When the expander drives the water pump body and does not reach the set working speed V1, the battery The output electric energy drives the water pump motor so that the water pump body reaches the set working speed V1; when the expander drives the water pump body to reach the set working speed V1, the expander independently drives the water pump body; when the expander drives the water pump body exceeds When the working speed V1 is set, the expander provides the power required by the water pump body and at the same time drives the water pump motor to generate electricity, recycles the system energy and stores it in the high-voltage power platform.

The above-mentioned air supply system includes an air filter, a flow meter, an air compressor, an intercooler, and a humidifier. The external air passes through the air filter, the flow meter, the air compressor, the intercooler, and the humidifier in sequence, and then is sent to the to the air inlet of the stack module; the tail exhaust gas discharged from the stack module is again humidified by the humidifier, flows through the back pressure valve, and the dehumidification device before being sent to the expander in the water pump. The expander performs work to drive the water pump. The pump body operates to provide power for the flow of coolant.

The above-mentioned cooling system includes a thermostatic valve, radiator, heater and water pump. The radiator and heater are connected in parallel using pipelines, and the thermostatic valve controls the flow of coolant to the radiator or heater; the water pump mainly provides power for the flow of coolant.

The above-mentioned DC-DC boost converter is electrically connected to the battery through a high-voltage bus, and the air compressor and water pump are electrically connected to the high-voltage bus.

A control method for a fuel cell system. The fuel cell system is the above-mentioned fuel cell system, and is characterized in that its working operation is controlled as follows:

Step 1: Before the fuel cell system is started, the water pump body rotates through the energy transmitted by the battery high-voltage bus;

Step 2: After the fuel cell system is started and running at a lower power, the pressure and heat of the tail exhaust are relatively small. At this time, the speed of the water pump driven by the expander cannot reach the speed of the water pump body driven by the fuel cell system. According to the speed requirements, the expander and battery jointly provide energy for the water pump body;

Step 3: When the fuel cell system is running at low to medium power, the pressure and heat of the exhaust gas are slightly larger. At this time, the speed of the water pump driven by the expander reaches the speed requirement of the water pump body of the fuel cell system. The expander alone is The water pump body provides energy;

Step 4: When the fuel cell system is running at high power, the pressure and heat of the tail exhaust are very large. At this time, the speed of the water pump body driven by the expander is greater than the speed requirement of the water pump body of the fuel cell system. The expander is a water pump. While the pump body rotates to provide energy, energy is recovered and transmitted to the high-voltage bus through the water pump motor and water pump controller, and the recovered electrical energy is stored on the high-voltage power platform.

Compared with the prior art, the present invention has the following effects:

1) A fuel cell system, including a stack module, a hydrogen supply system, an air supply system and a cooling system. The cooling system includes a water pump, which drives the coolant to continuously flow to take away heat. It is characterized in that: the water pump is an integrated The water pump of the expander includes an expander, a water pump body, a water pump motor and a water pump controller. The water pump controller controls the work of the water pump motor. The expander is coupled to one end of the rotating shaft of the water pump motor, and the other end of the rotating shaft of the water pump motor is coupled to the water pump body. , use the stack module to discharge the reacted exhaust gas and input it into the expander. The expander performs work to drive the water pump body to operate, providing power for the flow of coolant in the cooling system. Since the technical requirements of the water pump are low, it is easier to integrate the expander. , with simple structure and reasonable layout, the water pump with expander aims to reduce input power and recover energy. It can easily implement effective control strategies and effectively solve the exhaust energy recovery problem of the fuel cell system. It has high energy utilization rate and effectively improves fuel efficiency. Battery system efficiency.

2) The control method of the fuel cell system of the present invention has a simple and effective control strategy and can effectively improve the efficiency of the fuel cell system.

3) Other advantages of the present invention are described in detail in the embodiment section.

Picture description:

Figure 1 is a schematic block diagram of a fuel cell in the prior art;

Figure 2 is a schematic block diagram of a fuel cell system according to an embodiment of the present invention;

Figure 3 is a schematic diagram of electrical connections of a fuel cell system according to Embodiment 1 of the present invention;

Figure 4 is a structural block diagram of a water pump of a fuel cell system according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a water pump of a fuel cell system according to an embodiment of the present invention.

Detailed ways:

The present invention will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings.

Example 1:

As shown in Figure 1 and Figure 2, the fuel cell system generally includes a stack module, a fuel cell system controller, a hydrogen supply system, an air supply system and a cooling system. The output end of the hydrogen supply system is connected to the hydrogen inlet of the stack module as The stack module provides hydrogen; the output end of the air supply system is connected to the air inlet of the stack module to provide air for the stack module; the hydrogen outlet of the stack module outputs the reacted mixed gas, and the mixed gas water vapor separator performs water vapor separation , separate hydrogen, water vapor and waste gas. The separated hydrogen is re-inputted to the hydrogen inlet of the stack module through a hydrogen circulation pump. The separated water vapor and waste gas are directly discharged as tail exhaust. The stack module, hydrogen supply system, air supply system and cooling system are controlled by the fuel cell system controller. The above-mentioned air supply system includes an air filter, a flow meter, an air compressor, an intercooler, and a humidifier. The external air passes through the air filter, the flow meter, the air compressor, the intercooler, and the humidifier in sequence, and then is sent to the to the air inlet of the stack module; the hydrogen supply system includes a proportional valve, a stop valve, and a pressure relief valve; the high-pressure hydrogen passes through the proportional valve and the stop valve, and then is sent to the hydrogen inlet of the stack module; the cooling system includes a thermostatic valve, a radiator, Heater and water pump, the radiator and heater are connected in parallel using pipelines, and the thermostatic valve controls the flow of coolant to the radiator or heater; the water pump mainly provides power for the flow of coolant.

As shown in Figures 2, 3, 4, and 5, this embodiment provides a fuel cell system, including a stack module, a hydrogen supply system, an air supply system, and a cooling system. The cooling system includes a water pump, and the water pump drives cooling The liquid continuously flows to take away heat, and is characterized in that: the water pump is a water pump with an integrated expander, including an expander 1, a water pump body 2, a water pump motor 3 and a water pump controller 4. The water pump controller 4 controls the work of the water pump motor 3. , the expander 1 is coupled to one end of the rotating shaft of the water pump motor 3, and the other end of the rotating shaft 31 of the water pump motor 3 is coupled to the water pump body 2, and the reacted exhaust gas discharged from the stack module is input to the expander 1, and passes through the expander 1 The work drives the water pump body 2 to operate, providing power for the flow of coolant in the cooling system. Since the technical requirements of the water pump are low, it is easier to integrate the expander, with simple structure and reasonable layout. The water pump with the expander aims to reduce the input power and recover energy, which can facilitate the implementation of effective control strategies and effectively solve the tail discharge of the fuel cell system. Gas energy recovery problem, high energy utilization rate, effectively improve the efficiency of fuel cell system. The water pump of the fuel cell has a single function. It is only used for heat dissipation of the fuel cell stack module and system components. The power is small, generally less than the power brought by the energy recovery contained in the exhaust exhaust, which facilitates the formulation of control strategies and energy recovery.

The output end of the stack module is electrically connected to the high-voltage power platform through a DC-DC boost converter. The electric energy output by the stack module is processed by the DC-DC boost converter and stored in the high-voltage power platform. The water pump motor 3 is an all-in-one machine that integrates the functions of a motor and a generator. The water pump motor 3 is electrically connected to the battery 5 through a high-voltage busbar. The electric energy provided by the battery 5 passes through the water pump controller 4 to make the water pump motor 3 drive the water pump body 2 to work. Either the expander 1 drives the water pump body 2 to work, or the expander 1 charges the battery 5 through the water pump motor 3 and the water pump controller 4 to realize energy recovery. Multiple working modes are formed to facilitate the formulation of various control strategies and improve the efficiency of the fuel cell system.

The high-voltage power platform of the present invention has been integrated with the DC-DC boost converter and is located in the same box. The output end of the DC-DC boost converter is connected to the input end of the high-voltage power platform. The output end of the power platform is connected to the high-voltage bus. The high-voltage power platform is a high-voltage power distribution module PDU, which is connected to various loads and used to supply power to each load. The loads include air compressors, water pumps, hydrogen circulation pumps, auxiliary DCDC etc.

The above-mentioned expander 1 and the water pump body 2 are coaxially arranged and arranged at both ends of the water pump motor 3. The structural arrangement is reasonable and compact. The expander and the water pump motor shaft are connected through a reduction device.

The above-mentioned expander 1 adopts a turbine expander 1, which has a simple structure and is easy to integrate.

The above-mentioned DC input source of the water pump controller 4 is connected to the high voltage bus of the battery 5 . Battery 5 is a storage battery and is easy to connect.

The above-mentioned water pump body 2 includes a pump casing 21. A pump chamber 22 is provided inside the pump casing 21. An impeller 23 is installed inside the pump chamber 22. A water inlet 211 and a water outlet 212 are provided on the pump casing 21 to communicate with the pump chamber 22. The water pump motor 3 The impeller 23 is installed on the other end of the rotating shaft 31, and the structure is simple.

The output power of the above-mentioned expander 1 is P1, and the output power of the water pump body 2 is P2. The water pump controller 4 controls the operation of the water pump motor 3 according to the output power P1 and the output power of the water pump body 2 P2. When the output power P1 of the expander 1 is less than the output power P2 of the water pump body 2, the battery 5 outputs electric energy to drive the water pump motor 3 to compensate for the power difference between P1 and P2; when the output power P1 of the expander 1 is equal to the water pump body 2 Output power P2, expander 1 provides all the power required by water pump body 2; when the output power P1 of expander 1 is greater than the output power P2 of water pump body 2, expander 1 provides the power required by water pump body 2, By driving the water pump motor 3 to generate electricity, the system energy is recycled and transmitted to the high-voltage bus. The energy recovered and transmitted to the high-voltage bus can be used to supply various loads connected to the high-voltage power platform, or can be stored in the battery. 5 in.

Of course, in order to make the control simpler, the water pump controller 4 makes a control strategy based on the difference between the real-time speed of the water pump body 2 and the set speed. The water pump controller 4 contains the set working speed V1 of the water pump body 2. The set working speed V1 of the water pump body 2 is determined according to the requirements of the cooling system. When the expander 1 drives the water pump body 2, the set working speed V1 is not reached. V1, the battery 5 outputs electric energy to drive the water pump motor 3, so that the water pump body 2 reaches the set working speed V1; when the expander 1 drives the water pump body 2 to reach the set working speed V1 of the water pump body 2, the expander 1 Independently drives the water pump body 2; when the expander 1 drives the water pump body 2 to exceed the set working speed V1, the expander 1 provides the power required by the water pump body 2 and at the same time drives the water pump motor 3 to generate electricity, recycling the system energy. And stored in the high-voltage power platform, the control strategy is more simplified and effectively implements energy recovery and makes full use of tail exhaust work to improve the energy efficiency index of the fuel cell system.

The working principle of the present invention: before the fuel cell system is started, especially before cold start, the water pump body 2 needs to be able to rotate independently. At this time, the water pump body 2 normally rotates through the energy transmitted by the high-voltage bus of the battery 5; in the fuel cell system After starting, when running at a lower power, the pressure and heat of the tail exhaust are relatively small. At this time, the speed at which the expander 1 drives the water pump body 2 may not meet the system's speed requirements for the water pump body 2. The expander 1 and the battery 5 jointly provide energy for the water pump body 2; when the fuel cell system is running at small and medium power, the pressure and heat of the tail exhaust are slightly larger. At this time, the expander 1 drives the water pump body 2 to reach the speed of the system to the water pump. The speed of the pump body 2 requires that the expander 1 alone provides energy for the water pump body 2; when the fuel cell system is running at high power, the pressure and heat of the tail exhaust are very large. At this time, the expander 1 drives the water pump body 2 The speed is greater than the system's speed requirement for the water pump body 2. The expander 1 provides energy for the rotation of the water pump body 2 and at the same time transmits energy recovery to the high-voltage bus through the water pump motor 3 and the water pump controller 4, effectively solving the problem of the tail end of the fuel cell system. Exhaust energy recovery problem can effectively improve the efficiency of fuel cell system.

The control strategy of the present invention: a. In the pre-starting stage of the fuel cell system: the battery 5 provides an energy source for the rotation of the water pump body 2 through the high-voltage bus; b. After the fuel cell system is started: the expander 1 drives the water pump body 2 to rotate, while the battery 5. The high-voltage bus is used to provide an energy source for the water pump body 2, and the water pump controller 4 controls the output energy according to the heat dissipation requirements of the system and the required speed of the water pump body 2.

The hydrogen in the stack module reacts with the oxygen in the air to form tail exhaust gas. The tail exhaust gas discharged from the stack module is again humidified by the humidifier, flows through the back pressure valve, and the dehumidification device before being sent to the water pump. The expander 1 drives the water pump body 2 to operate through the work of the expander 1, providing power for the flow of coolant.

In order to further simplify the control strategy, the fuel cell system is divided into two stages: one is the pre-start stage; the other is the stage after the fuel cell system is started, so the control strategy is divided into two steps:

a. Pre-starting stage of the fuel cell system: The battery provides energy source for the rotation of the water pump through the high-voltage bus;

b. The post-startup stage of the fuel cell system: The expander drives the water pump to rotate, and the high-voltage bus of the battery provides an energy source for the water pump. The water pump controller sets the required speed of the water pump according to the heat dissipation needs of the system to control the output energy.

Example 2:

A control method for a fuel cell system. The fuel cell system is the fuel cell system described in Embodiment 1. It is characterized in that its operation control is as follows:

Step 1: Before the fuel cell system is started, the water pump body 2 rotates through the energy transmitted by the high-voltage bus of the battery 5;

Step 2: After the fuel cell system is started and running at a low power, the pressure and heat of the tail exhaust are relatively small. At this time, the speed of the water pump body 2 driven by the expander 1 cannot reach the speed of the water pump driven by the fuel cell system. According to the rotation speed requirement of body 2, the expander 1 and the battery 5 jointly provide energy for the water pump body 2;

Step 3: When the fuel cell system is running at low or medium power, the pressure and heat of the exhaust gas are slightly larger. At this time, the speed of the water pump body 2 driven by the expander 1 reaches the speed requirement of the fuel cell system for the water pump body 2, and the expansion Machine 1 alone provides energy for water pump body 2;

Step 4: When the fuel cell system is running at high power, the pressure and heat of the tail exhaust are very large. At this time, the speed of the expander 1 driving the water pump body 2 is greater than the speed requirement of the fuel cell system for the water pump body 2, and the expansion The machine 1 provides energy for the rotation of the water pump body 2 and at the same time recovers and transmits energy to the high-voltage bus through the water pump motor 3 and the water pump controller 4.

The control strategy of the present invention is simple and effective, and can effectively improve the efficiency of the fuel cell system.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention are all equivalent. All substitution methods are included in the protection scope of the present invention.

Claims

A fuel cell system includes a stack module, a hydrogen supply system, an air supply system and a cooling system. The cooling system includes a water pump. The water pump drives the coolant to continuously flow to take away heat. The water pump is an integrated expander. The water pump includes an expander (1), a water pump body (2), a water pump motor (3) and a water pump controller (4). The water pump controller (4) controls the work of the water pump motor (3), and the expander (1) is coupled. To one end of the rotating shaft of the water pump motor (3), the other end of the rotating shaft of the water pump motor (3) is coupled to the water pump body (2). The stack module is used to discharge the reacted exhaust gas and input it into the expander (1). Through the expansion The machine (1) works to drive the water pump body (2) to operate, providing power for the flow of coolant in the cooling system.
A fuel cell system according to claim 1, characterized in that: the output end of the stack module is electrically connected to the high-voltage power platform through a DC-DC boost converter, and the electric energy output by the stack module is boosted by the DC-DC converter. After processing by the voltage converter, it is stored in the high-voltage power platform.
A fuel cell system according to claim 2, characterized in that: the water pump motor (3) is an integrated machine integrating the functions of a motor and a generator, and the water pump motor (3) is electrically connected to the battery (5) through a high-voltage busbar. connection, the electric energy provided by the battery (5) passes through the water pump controller (4) to cause the water pump motor (3) to drive the water pump body (2) to work, or the expander (1) to drive the water pump body (2) to work, or the expander ( 1) Energy recovery is achieved by charging the battery (5) through the water pump motor (3) and the water pump controller (4).
A fuel cell system according to claim 3, characterized in that: the expander (1) and the water pump body (2) are coaxially arranged and arranged at both ends of the water pump motor (3).
A fuel cell system according to claim 4, characterized in that: the expander (1) adopts a turbine expander.
A fuel cell system according to claim 5, characterized in that: the DC input source of the water pump controller (4) is connected to the high-voltage bus of the battery (5).
A fuel cell system according to any one of claims 1 to 6, characterized in that: the water pump body (2) includes a pump casing (21), and a pump chamber (22) is provided inside the pump casing (21). The impeller (23) is installed inside (22), the water inlet (211) and the water outlet (212) are provided on the pump casing (21) to communicate with the pump chamber (22), and the other end of the rotating shaft (31) of the water pump motor (3) is installed Upper impeller (23).
A fuel cell system according to claim 7, characterized in that: the output power of the expander (1) is P1, the output power of the water pump body (2) is P2, and the output power of the water pump controller (4) is P1. The output power of the water pump body (2) is P2 to control the operation of the water pump motor (3).
A fuel cell system according to claim 8, characterized in that when the output power P1 of the expander (1) is less than the output power P2 of the water pump body (2), the battery (5) outputs electric energy to drive the water pump motor (3) , to compensate for the power difference between P1 and P2; when the output power P1 of the expander (1) is equal to the output power P2 of the water pump body (2), the expander (1) provides all the needs of the water pump body (2) Power; when the output power P1 of the expander (1) is greater than the output power P2 of the water pump body (2), the expander (1) provides the power required by the water pump body (2) and generates electricity by driving the water pump motor (3). System energy is recovered and transferred to the high-voltage bus.
A fuel cell system according to claim 7, characterized in that: the water pump controller (4) contains a set working speed V1 of the water pump body (2), and a set working speed V1 of the water pump body (2). It is determined according to the cooling system requirements. When the expander (1) drives the water pump body (2) and does not reach the set working speed V1, the battery (5) outputs electric energy to drive the water pump motor (3), so that the water pump body (2) reaches the set working speed V1; when the expander (1) drives the water pump body (2) to reach the set working speed V1 of the water pump body (2), the expander (1) independently drives the water pump body (2); When the expander (1) drives the water pump body (2) to exceed the set working speed V1, the expander (1) not only provides the power required by the water pump body (2), but also generates electricity by driving the water pump motor (3), which contributes to the system energy. Recycled and stored in high-voltage electrical platforms.
A fuel cell system according to claim 7, characterized in that: the air supply system includes an air filter, a flow meter, an air compressor, an intercooler and a humidifier, and the external air passes through the air filter and the flow meter in sequence. , air compressor, intercooler and humidifier, and then sent to the air inlet of the stack module; the tail exhaust gas discharged from the stack module is again humidified by the humidifier, flows through the back pressure valve, and the dehumidification device After being sent to the expander 1 in the water pump, the work of the expander 1 drives the water pump body 2 to operate, providing power for the flow of the coolant.
A fuel cell system according to claim 11, characterized in that: the cooling system includes a thermostatic valve, a radiator, a heater and a water pump, the radiator and the heater are connected in parallel using pipelines, and the thermostatic valve controls the flow of coolant to the radiator. Or heater; the water pump mainly provides power for the flow of coolant.
A fuel cell system according to claim 12, characterized in that: the DC-DC boost converter and the battery (5) are electrically connected through a high-voltage bus, and the air compressor and water pump are electrically connected to the high-voltage bus.
A control method for a fuel cell system, the fuel cell system being any of the fuel cell systems described in claims 1 to 13, characterized in that its operation control is as follows:

Step 1: Before the fuel cell system is started, the water pump body (2) rotates through the energy transmitted by the high-voltage bus of the battery (5);

Step 2: After the fuel cell system is started and runs at a lower power, the pressure and heat of the tail exhaust are relatively small. At this time, the speed of the expander (1) driving the water pump body (2) cannot reach the speed of the fuel cell. The system requires the speed of the water pump body (2). The expander (1) and the battery (5) jointly provide energy for the water pump body (2);

Step 3: When the fuel cell system is running at low to medium power, the pressure and heat of the exhaust gas are slightly larger. At this time, the expander (1) drives the water pump body (2) at a speed that reaches the level of the fuel cell system's pressure on the water pump body (2). ), the expander (1) alone provides energy to the water pump body (2);

Step 4: When the fuel cell system is running at high power, the pressure and heat of the tail exhaust are very large. At this time, the speed of the expander (1) driving the water pump body (2) is greater than the speed of the water pump body (2) driven by the fuel cell system. ), the expander (1) provides energy for the rotation of the water pump body (2) and at the same time transmits energy recovery to the high-voltage bus through the water pump motor (3) and the water pump controller (4).