Fuel cell vehicle with multifunctional braking resistor

Abstract

The application provides a fuel cell vehicle with a multifunctional braking resistor, and belongs to the technical field of fuel cells, and solves the problems of slow starting in winter and small braking force in long downhill driving of the prior art vehicle. The vehicle is provided with a vehicle controller, a fuel cell engine, a power battery, a power distribution unit, a braking resistor controller, a braking resistor, a motor controller, a motor and vehicle accessories, and can realize the multifunctional braking function. The vehicle controller is used for identifying the winter environment, controlling the heating of the braking resistor to heat the cab and the power battery, identifying the power battery when the vehicle is in long downhill driving, starting the built-in energy recovery program to convert the kinetic energy of the vehicle into electric energy and store the electric energy in the power battery, identifying the full power battery, starting the braking resistor and controlling the power of the braking resistor to provide the rated braking force for the vehicle.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell vehicle with a multifunctional braking resistor. Background Technology

[0002] Fuel cell vehicles are increasingly favored by the automotive industry because they are cleaner and pollution-free than gasoline vehicles, and have lower operating costs.

[0003] In low-temperature applications, the performance of the power battery in fuel cell vehicles deteriorates, and the charging and discharging capacity is limited by temperature, affecting the vehicle's power performance and resulting in longer start-up times in winter. Furthermore, under extreme conditions such as long downhill slopes, there is a risk of insufficient braking force even when the power battery is fully charged, posing a safety concern regarding vehicle braking. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a fuel cell vehicle with a multifunctional braking resistor to solve the problems of slow start-up and insufficient braking force when driving on long downhill slopes in existing vehicles.

[0005] This invention provides a fuel cell vehicle with a multifunctional braking resistor. The vehicle includes a vehicle controller, a fuel cell engine, a power battery, a power distribution unit, a braking resistor controller, a braking resistor, a motor controller, a motor, and vehicle accessories.

[0006] The power distribution unit has five ports: one port connected to the fuel cell engine, two ports connected to the power battery, three ports connected to the braking resistor via the braking resistor controller, four ports connected to the motor via the motor controller, and five ports connected to the vehicle accessories.

[0007] The braking resistor is connected to the heating system in the vehicle's cab and the heating system on the power battery.

[0008] The vehicle controller is used to identify winter conditions and control the heating of the braking resistor to heat the cab and the power battery. When the vehicle is going downhill for a long time, it will detect that the power battery is not fully charged and start the built-in energy recovery program to convert the vehicle's kinetic energy into electrical energy and store it in the power battery. When the power battery is fully charged, it will turn on the braking resistor and control its power to provide the vehicle with rated braking force.

[0009] The beneficial effects of the above technical solution are as follows: In the vehicle's power system, a shared braking resistor scheme is adopted. In winter, when the ambient temperature is low, the braking resistor generates heat to warm the cab and simultaneously heat the power battery. During long downhill driving conditions, energy recovery mode is used as much as possible to recover and store kinetic energy in the power battery. When the power battery is fully charged, the braking resistor is activated and its power is controlled to provide sufficient braking force to ensure vehicle safety.

[0010] Based on further improvements to the aforementioned vehicle, the braking resistor includes a brake resistor.

[0011] Furthermore, the braking resistor is located in the coolant circuit of the fuel cell engine; and,

[0012] The coolant circuit of the fuel cell engine is equipped with a first radiator, a first water pump, a four-way valve, and a heat exchanger, and is connected to a braking resistor, a heating device in the vehicle's cab, and a heating device on the power battery. The liquid flowing out from port one of the four-way valve after passing through the first radiator, the liquid flowing out from port three of the four-way valve after passing through branch one of the heat exchanger, and the liquid flowing out from port two of the four-way valve after passing through the heating device in the vehicle's cab are combined into one stream, and then flow into port four of the four-way valve through the first water pump and the braking resistor in sequence. Branch two of the heat exchanger is connected to the power battery.

[0013] Furthermore, the fuel cell engine's coolant circuit is also equipped with a water replenishment tank; and,

[0014] The input end of the water tank is connected to the output end of the first radiator, and its output end is connected to the water supply end of the first water pump, which is used to maintain the liquid in the coolant circuit of the fuel cell engine at a set amount range.

[0015] Furthermore, the vehicle is equipped with a water-cooled unit, which is also connected to the coolant circuit of the fuel cell engine.

[0016] Water-cooled units are used to dissipate heat from at least one of the fuel cell engine, motor, or cab cooling system.

[0017] The output terminal of branch two of the heat exchanger is connected to the input terminal of branch two of the heat exchanger via a water-cooled unit and a power battery in sequence.

[0018] Furthermore, the water-cooled unit further includes a unit casing, and a second water pump, a second radiator, and a three-way valve integrated within the unit casing; wherein,

[0019] The unit casing is equipped with a liquid inlet and a liquid outlet; the liquid inlet is connected to the input terminal one of the three-way valve via the second water pump, and the other is connected to the input terminal two of the three-way valve via the second radiator; the liquid outlet is connected to the output terminal of the three-way valve.

[0020] Furthermore, the water-cooled unit also integrates a PTC heater; wherein,

[0021] The liquid inlet of the unit casing is pumped through a PTC heater and connected to the input terminal of the three-way valve, while the other path is connected to the input terminal of the three-way valve through the second radiator; the liquid outlet is connected to the output terminal of the three-way valve.

[0022] Furthermore, the water-cooled unit is used to provide heating and cooling functions for the fuel cell engine, and the vehicle controller executes the following program to complete the cold start and operation functions of the fuel cell in winter conditions:

[0023] S1. Obtain the ambient temperature T;

[0024] S2. Identify whether the ambient temperature T is less than the set value t1 and the liquid temperature T3 at the output end of the second branch of the heat exchanger is less than the set value t2. If yes, proceed to the next step; otherwise, control the fuel cell engine to start normally.

[0025] S3. Control the start of the PTC heater in the water-cooled unit and control the three-way valve to open the small circulation mode to heat the fuel cell engine;

[0026] S4. Control the fuel cell engine to enter self-start mode;

[0027] S5. After the fuel cell engine enters the self-starting mode at the set time, the duty cycle of the braking resistor controller is adjusted synchronously according to the output power P of the fuel cell engine to adjust the heating power of the heating device in the vehicle's cab and the heating device on the power battery.

[0028] S6. Obtain the liquid temperature T2 at the liquid inlet of the heating device in the vehicle's cab and the liquid temperature T3 at the output of the second branch of the heat exchanger;

[0029] S7. The four-way valve is controlled according to the liquid temperatures T2 and T3 to adjust the flow rate of different circuits to meet the temperature requirements of the vehicle cab and the power battery.

[0030] S8. During the adjustment process, identify whether the liquid temperature T3 is greater than the set value t3. If so, control the three ports of the four-way valve to close to disconnect the branch where the heat exchanger is located, and simultaneously reduce the power of the braking resistor until the fuel cell engine shuts down. Otherwise, repeat steps S5 to S8; and t2 < t3.

[0031] S9. Simultaneously execute step S8, that is, during the adjustment process, identify whether the liquid temperature T2 is greater than the set value t4. If so, control the two ports of the four-way valve to close to disconnect the branch where the heating device is located in the vehicle's cab, and simultaneously reduce the power of the braking resistor so that the liquid temperature T2 is maintained within the set range [t4-d, t4+d] until the fuel cell engine is shut down; and d≤2℃, t4 is 16~30℃.

[0032] Furthermore, the vehicle controller also executes the following program to complete the braking function of the vehicle under long downhill conditions:

[0033] S10. Identify whether the vehicle is in braking mode and the SOC of the power battery is greater than the upper limit of the remaining power capacity soc1 of the power battery. If yes, proceed to the next step; otherwise, control the vehicle to switch from power supply mode to braking resistor consumption mode.

[0034] S11. Obtain the power supply P of the motor controller, and adjust the duty cycle of the braking resistor controller synchronously according to the power supply P to change the power consumption of the braking resistor, so as to ensure that the braking force of the vehicle meets the usage requirements.

[0035] S12. Obtain the liquid temperature T1 at the outlet of the first radiator, and identify whether the liquid temperature T1 is less than the set value t5. If so, control the cooling fan at the first radiator to turn off; otherwise, return to step S11; and t1 < t5.

[0036] Furthermore, the fuel cell vehicle is equipped with the following data monitoring devices:

[0037] An ambient temperature sensor, installed inside the vehicle compartment, is used to acquire the ambient temperature T.

[0038] The first temperature sensor is installed on the inner wall of the pipe at the outlet of the first radiator to obtain the liquid temperature T1 at the outlet of the first radiator.

[0039] The second temperature sensor is located on the inner wall of the pipe at the liquid input end of the heating device in the driver's cab of the vehicle, and is used to obtain the liquid temperature T2 at the liquid input end of the heating device in the driver's cab of the vehicle.

[0040] The third temperature sensor is located on the inner wall of the pipe at the output end of branch two of the heat exchanger, and is used to measure the liquid temperature T3 at the output end of branch two of the heat exchanger.

[0041] The summary section is provided to present the chosen concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify essential or essential features of the invention, nor is it intended to limit the scope of the invention. Attached Figure Description

[0042] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0043] Figure 1 A schematic diagram of the control components of the fuel cell vehicle in Embodiment 1 is shown;

[0044] Figure 2 A schematic diagram of the cooling fluid circuit connection of the fuel cell engine in Example 2 is shown.

[0045] Figure 3 A schematic diagram of the internal structure of the water-cooled unit in Embodiment 2 is shown;

[0046] Figure 4 A schematic diagram of the cold start and operation control process of the fuel cell in winter environment in Example 2 is shown;

[0047] Figure 5 A schematic diagram of the braking control process for a vehicle on a long downhill slope in Example 2 is shown.

[0048] Figure Labels

[0049] 1 - Port 1; 2 - Port 2; 3 - Port 3; 4 - Port 4; CAN - Controller Area Network; T1 - First Temperature Sensor; T2 - Second Temperature Sensor; T3 - Third Temperature Sensor. Detailed Implementation

[0050] Embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0051] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0052] Example 1

[0053] One embodiment of the present invention discloses a fuel cell vehicle with a multifunctional braking resistor, such as... Figure 1 As shown, the vehicle is equipped with a vehicle controller, fuel cell engine, power battery, power distribution unit, braking resistor controller, braking resistor, motor controller, motor and vehicle accessories.

[0054] Among them, port 1 of the power distribution unit is connected to the fuel cell engine, port 2 is connected to the power battery, port 3 is connected to the braking resistor via the braking resistor controller, port 4 is connected to the motor via the motor controller, and port 5 is connected to the vehicle accessories.

[0055] The braking resistor is connected to the heating system in the vehicle's cab and the heating system on the power battery. The braking resistor is a type of corrugated resistor, primarily used to help the motor convert the regenerative electrical energy generated during rapid braking into heat energy; it is essentially a braking unit plus a resistor.

[0056] The vehicle controller is used to identify winter conditions and control the heating of the braking resistor to heat the cab and the power battery. When the vehicle is going downhill for a long time, it will detect that the power battery is not fully charged and start the built-in energy recovery program to convert the vehicle's kinetic energy into electrical energy and store it in the power battery. When the power battery is fully charged, it will turn on the braking resistor and control its power to provide the vehicle with rated braking force.

[0057] Compared with existing technologies, the fuel cell vehicle provided in this embodiment adopts a shared braking resistor scheme in its power system. In low winter temperatures, the braking resistor generates heat to warm the cab and simultaneously heat the power battery. During long downhill driving, energy recovery mode is used as much as possible to recover and store kinetic energy in the power battery. When the power battery is fully charged, the braking resistor is activated and its power is controlled to provide sufficient braking force to ensure vehicle safety.

[0058] Example 2

[0059] An improvement based on Example 1 is made, wherein the braking resistor includes a brake resistor.

[0060] Preferably, the braking resistor is located in the coolant circuit of the fuel cell engine.

[0061] The coolant circuit of the fuel cell engine is equipped with a first radiator, a first water pump, a four-way valve, and a heat exchanger, and is connected to a braking resistor, a heating system in the vehicle's cab, and a heating system on the power battery, such as... Figure 2 As shown. The liquid flowing out from port 1 of the four-way valve after passing through the first radiator, the liquid flowing out from port 3 of the four-way valve after passing through branch 1 of the heat exchanger, and the liquid flowing out from port 2 of the four-way valve after passing through the heating device in the vehicle's cab are combined into one line, and then flow into port 4 of the four-way valve in sequence through the first water pump and the brake resistor; branch 2 of the heat exchanger is connected to the power battery.

[0062] Preferably, the coolant circuit of the fuel cell engine is further provided with a water replenishment tank. The input end of this water replenishment tank is connected to the output end of the first radiator, and its output end is connected to the water supply end of the first water pump, to maintain the liquid level in the coolant circuit of the fuel cell engine within a set range.

[0063] Preferably, the vehicle is also equipped with a water-cooled unit, which is also connected to the coolant circuit of the fuel cell engine. Furthermore, the water-cooled unit is used to dissipate heat from at least one of the fuel cell engine, the motor, and the cab cooling system.

[0064] The output terminal of branch two of the heat exchanger is connected to the input terminal of branch two of the heat exchanger via a water-cooled unit and a power battery in sequence.

[0065] Preferably, the water-cooled unit further includes a unit casing, and a second water pump, a second radiator, and a three-way valve integrated within the unit casing, such as... Figure 3 As shown. The unit casing is equipped with a liquid inlet and a liquid outlet; the liquid inlet is connected to the input terminal of a three-way valve via a second water pump, and the other is connected to the input terminal of a three-way valve via a second radiator; the liquid outlet is connected to the output terminal of the three-way valve.

[0066] Preferably, the water-cooled unit also integrates a PTC heater. The liquid inlet of the unit casing, after being pumped, connects to the input terminal of a three-way valve via the PTC heater, and the other connection connects to the input terminal of the three-way valve via a second radiator; the liquid outlet is connected to the output terminal of the three-way valve.

[0067] Preferably, the water-cooled unit is used to provide heating and cooling functions for the fuel cell engine, and the vehicle controller executes the following program to complete the cold start and operation functions of the fuel cell in winter conditions, such as... Figure 4 As shown:

[0068] S1. Obtain the ambient temperature T;

[0069] S2. Identify whether the ambient temperature T is less than the set value t1 and the liquid temperature T3 at the output end of the second branch of the heat exchanger is less than the set value t2. If yes, proceed to the next step; otherwise, control the fuel cell engine to start normally.

[0070] S3. Control the start of the PTC heater in the water-cooled unit and control the three-way valve to open the small circulation mode to heat the fuel cell engine;

[0071] S4. Control the fuel cell engine to enter self-start mode;

[0072] S5. After the fuel cell engine enters the self-starting mode at the set time, the duty cycle of the braking resistor controller is adjusted synchronously according to the output power P of the fuel cell engine to adjust the heating power of the heating device in the vehicle's cab and the heating device on the power battery.

[0073] S6. Obtain the liquid temperature T2 at the liquid inlet of the heating device in the vehicle's cab and the liquid temperature T3 at the output of the second branch of the heat exchanger;

[0074] S7. The four-way valve is controlled according to the liquid temperatures T2 and T3 to adjust the flow rate of different circuits to meet the temperature requirements of the vehicle cab and the power battery.

[0075] S8. During the adjustment process, identify whether the liquid temperature T3 is greater than the set value t3. If so, control the four-way valve to close port 3 to disconnect the branch where the heat exchanger is located, and simultaneously reduce the power of the braking resistor until the fuel cell engine shuts down. Otherwise, execute steps S5 to S8 again; and t2 < t3 (t2 and t3 are a set of power battery system operating temperature judgment thresholds. For example, t2 is set to 5°C and t3 is set to 25°C).

[0076] S9. Simultaneously execute step S8, that is, during the adjustment process, identify whether the liquid temperature T2 is greater than the set value t4. If so, control the port 2 of the four-way valve to close to disconnect the branch where the heating device in the vehicle cab is located, and simultaneously reduce the power of the braking resistor so that the liquid temperature T2 is maintained within the set range [t4-d, t4+d] until the fuel cell engine is shut down; and d≤2℃, t4 is 16~30℃ (t4 is the threshold for judging the working temperature of the cab heating system, and its range is consistent with the temperature set on the air conditioning panel).

[0077] Preferably, the vehicle controller also executes the following program to complete the braking function of the vehicle under long downhill conditions, such as... Figure 5 As shown:

[0078] S10. Identify whether the vehicle is in braking mode and the SOC of the power battery is greater than the upper limit of the remaining power charge soc1 (which can be set to 80%). If yes, proceed to the next step; otherwise, control the vehicle to switch from power supply (fuel cell power generation) mode to power battery mode (power battery charging) to braking resistor consumption mode (braking resistor consumption).

[0079] S11. Obtain the power supply P of the motor controller (Source: GB / T18488.1-2015 Technical Conditions for Drive Motor Systems for Electric Vehicles 5.4.13), and adjust the duty cycle of the braking resistor controller synchronously according to the power supply P to change the power consumption of the braking resistor, so as to ensure that the braking force of the vehicle meets the usage requirements.

[0080] S12. Obtain the liquid temperature T1 at the outlet of the first radiator, and identify whether the liquid temperature T1 is less than the set value t5. If so, control the cooling fan at the first radiator to turn off; otherwise, return to step S11; and t1 < t5 (t1 and t5 are a set of operating temperature judgment thresholds for the fuel cell system. For example, t1 is set to 0°C and t5 is set to 40°C).

[0081] Preferably, the data monitoring equipment installed on the fuel cell vehicle includes an ambient temperature sensor, a first temperature sensor T1, a second temperature sensor T2, and a third temperature sensor T3.

[0082] An ambient temperature sensor is installed inside the vehicle compartment to obtain the ambient temperature T.

[0083] The first temperature sensor T1 is located on the inner wall of the pipe at the outlet of the first radiator and is used to obtain the liquid temperature T1 at the outlet of the first radiator.

[0084] The second temperature sensor T2 is located on the inner wall of the pipe at the liquid input end of the heating system in the driver's cab of the vehicle, and is used to obtain the liquid temperature T2 at the liquid input end of the heating system in the driver's cab of the vehicle.

[0085] The third temperature sensor T3 is located on the inner wall of the pipe at the output end of the second branch of the heat exchanger, and is used to measure the liquid temperature T3 at the output end of the second branch of the heat exchanger.

[0086] Compared with the prior art, the fuel cell vehicle with a multifunctional braking resistor provided in this embodiment has the following beneficial effects:

[0087] 1. A small circulation mode is adopted in the power battery cooling circuit to reduce the system heat capacity and accelerate the temperature rise rate of the power battery.

[0088] 2. A shared braking resistor scheme reduces system complexity and improves the utilization rate of the braking resistor.

[0089] 3. The power battery can be heated by dual heat sources and a small cycle mode can be adopted, which improves the temperature rise rate of the power battery and enhances the applicability of the vehicle.

[0090] 4. Under extreme long downhill conditions, recover energy as much as possible to improve system efficiency; at the same time, the braking resistor can ensure sufficient braking force for the vehicle to ensure vehicle safety.

[0091] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to the prior art of the embodiments, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell vehicle with a multifunctional braking resistor, characterized in that, The vehicle is equipped with a vehicle controller, fuel cell engine, power battery, power distribution unit, braking resistor controller, braking resistor, motor controller, motor, and vehicle accessories; among which, The power distribution unit has five ports: one port connected to the fuel cell engine, two ports connected to the power battery, three ports connected to the braking resistor via the braking resistor controller, four ports connected to the motor via the motor controller, and five ports connected to the vehicle accessories. The braking resistor is connected to the heating system in the vehicle's cab and the heating system on the power battery. The vehicle controller is used to identify winter conditions and control the heating of the braking resistor to heat the cab and the power battery. When the vehicle is going downhill for a long time, it will identify that the power battery is not fully charged and start the built-in energy recovery program to convert the vehicle's kinetic energy into electrical energy and store it in the power battery. When the power battery is fully charged, it will turn on the braking resistor and control its power to provide the vehicle with rated braking force. The braking resistor includes a braking resistor; the braking resistor is located in the coolant circuit of the fuel cell engine; and... The coolant circuit of the fuel cell engine is equipped with a first radiator, a first water pump, a four-way valve, and a heat exchanger, and is connected to a braking resistor, a heating device in the vehicle's cab, and a heating device on the power battery. The liquid flowing out from port one of the four-way valve after passing through the first radiator, the liquid flowing out from port three of the four-way valve after passing through branch one of the heat exchanger, and the liquid flowing out from port two of the four-way valve after passing through the heating device in the vehicle's cab are combined into one stream, and then flow into port four of the four-way valve through the first water pump and the braking resistor in sequence. Branch two of the heat exchanger is connected to the power battery. The vehicle is also equipped with a water-cooled unit, which is also connected to the coolant circuit of the fuel cell engine. Water-cooled units are used to dissipate heat from at least one of the fuel cell engine, motor, or cab cooling system. The output terminal of the second branch of the heat exchanger is connected to the input terminal of the second branch of the heat exchanger via a water-cooled unit and a power battery in sequence. The water-cooled unit further includes a unit casing, and a second water pump, a second radiator, and a three-way valve integrated within the unit casing; wherein, The unit casing is equipped with a liquid inlet and a liquid outlet; the liquid inlet is connected to the input terminal one of a three-way valve via the second water pump, and the other is connected to the input terminal two of the three-way valve via the second radiator; the liquid outlet is connected to the output terminal of the three-way valve. The water-cooled unit also integrates a PTC heater; among which, The liquid inlet of the unit casing is pumped through a PTC heater and connected to the input terminal of a three-way valve, and another path is connected to the input terminal of a three-way valve through a second radiator; the liquid outlet is connected to the output terminal of the three-way valve. The water-cooled unit is used to provide heating and cooling functions for the fuel cell engine. Furthermore, the vehicle controller executes the following program to complete the cold start and operation functions of the fuel cell in winter conditions: S1. Obtain ambient temperature T ; S2. Identify whether the ambient temperature is met. T Less than the set value t 1. And the liquid temperature at the output end of branch two of the heat exchanger T 3 Less than the set value t 2. If yes, proceed to the next step; otherwise, control the fuel cell engine to start normally. S3. Control the start of the PTC heater in the water-cooled unit and control the three-way valve to open the small circulation mode to heat the fuel cell engine; S4. Control the fuel cell engine to enter self-start mode; S5. After the set time for the fuel cell engine to enter the self-start mode, based on the output power of the fuel cell engine... P The duty cycle of the brake resistor controller is adjusted synchronously to adjust the heating power of the heating device in the vehicle's cab and the heating device on the power battery. S6. Obtain the liquid temperature at the liquid inlet of the heating system in the vehicle's cab. T 2. Liquid temperature at the output end of branch two of the heat exchanger T 3; S7. Based on liquid temperature T 2. T 3. Control the four-way valve to adjust the flow rate of different circuits to meet the temperature requirements of the vehicle cab and the power battery. S8. Identify whether the liquid temperature is met during the adjustment process. T 3 is greater than the set value t 3. If so, close port three of the four-way valve to disconnect the branch where the heat exchanger is located, and simultaneously reduce the power of the braking resistor until the fuel cell engine shuts down; otherwise, repeat steps S5~S8. t 2< t 3; S9. Execute step S9 simultaneously with step S8, that is, identify whether the liquid temperature is met during the adjustment process. T 2 is greater than the set value t 4. If so, close port two of the four-way valve to disconnect the branch containing the heating system in the vehicle's cab, simultaneously reducing the power of the braking resistor and lowering the fluid temperature. T 2. Maintain within the set range [ t 4- d , t 4+ d [Until the fuel cell engine shuts down; and] d ≤2℃, t 4 is 16~30℃.

2. The fuel cell vehicle with a multifunctional braking resistor according to claim 1, characterized in that, The fuel cell engine's coolant circuit also includes a water replenishment tank; and, The input end of the water tank is connected to the output end of the first radiator, and its output end is connected to the water supply end of the first water pump, which is used to maintain the liquid in the coolant circuit of the fuel cell engine at a set amount range.

3. The fuel cell vehicle with a multifunctional braking resistor according to claim 1, characterized in that, The vehicle controller also executes the following program to complete the braking function of the vehicle under long downhill conditions: S10. Identify whether the vehicle is in braking mode and the SOC of the power battery is greater than the upper limit of the remaining power capacity soc1 of the power battery. If yes, proceed to the next step; otherwise, control the vehicle to switch from power supply mode to braking resistor consumption mode. S11. Obtain the power supply from the motor controller. P According to the power supply P The duty cycle of the brake resistor controller is adjusted synchronously to change the power consumption of the brake resistor, ensuring that the vehicle's braking force meets the usage requirements. S12. Obtain the liquid temperature at the outlet of the first radiator. T 1. Identify whether the liquid temperature is met. T 1 is less than the set value t 5. If yes, turn off the cooling fan at the first radiator; otherwise, return to step S11; and t 1 < t 5.

4. The fuel cell vehicle with a multifunctional braking resistor according to claim 3, characterized in that, The fuel cell vehicle is equipped with the following data monitoring devices: An ambient temperature sensor, installed inside the vehicle compartment, is used to acquire the ambient temperature. T ; A first temperature sensor is installed on the inner wall of the pipe at the outlet of the first radiator to obtain the liquid temperature at the outlet of the first radiator. T 1; The second temperature sensor is located on the inner wall of the pipe at the liquid inlet of the heating system in the vehicle's driver's cab, and is used to obtain the liquid temperature at the liquid inlet of the heating system in the vehicle's driver's cab. T 2; The third temperature sensor is located on the inner wall of the pipe at the output end of branch two of the heat exchanger, and is used to obtain the liquid temperature at the output end of branch two of the heat exchanger. T 3.

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