A high-voltage side coordinated control method for a fuel cell system during startup

Abstract

The present invention discloses a high-voltage side coordinated control method of a fuel cell system during startup, comprising: building a high-voltage topology structure including a fuel cell stack, a DCDC converter, a power battery, a heater, a first relay unit, a second relay unit, a third relay unit and a fourth relay unit; performing a state self-check on each of the above high-voltage components to determine that the fuel cell system is in a state that allows startup; after receiving a startup enable requirement fed back by a vehicle controller, controlling the fuel cell system to enter a startup mode; controlling the heater to adjust the voltage of the fuel cell stack, and then adjusting the operating state of the DCDC converter; and checking the startup state of the fuel cell system in combination with the current output voltage of the fuel cell stack and the current working states of the third relay unit and the fourth relay unit. The present invention can quickly reduce the high potential residence time of the fuel cell system during startup by connecting a heater in series with the fuel cell stack.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a high-voltage side coordinated control method of a fuel cell system during startup. Background Art

[0002] The voltage of a fuel cell system is mainly composed of static potential, activation polarization, ohmic polarization, and mass transfer polarization. As the system output current increases, the polarization phenomenon becomes more obvious, and the system output voltage tends to decrease. The open circuit voltage of the system at the time of startup will be at its highest state. However, the high potential of the fuel cell system at startup causes the cathode of the stack to easily produce hydrogen peroxide free radicals, thereby attacking the proton exchange membrane in the fuel cell, causing the proton exchange membrane to degrade or easily perforate, and causing damage to the safety and life of the stack. Therefore, how to quickly reduce or avoid the high potential of the fuel cell system at startup is a problem that the present invention needs to solve.

[0003] The current solution to this problem is mainly to add a discharge resistor in the DCDC high-voltage converter. However, as the power of the fuel cell system design increases and the number of fuel cell stacks increases, the discharge resistor cannot effectively and quickly reduce the high potential of the stack, which will cause significant damage to the proton exchange membrane in the fuel cell. Summary of the invention

[0004] The present invention provides a high-voltage side coordinated control method for a fuel cell system during startup to solve one or more technical problems existing in the prior art and at least provide a beneficial option or create conditions.

[0005] An embodiment of the present invention provides a high-voltage side coordinated control method of a fuel cell system during startup, the method comprising:

[0006] Building a high-voltage topology structure of a fuel cell system, which includes a fuel cell stack, a DCDC converter, a power battery, a heater, a first relay unit, a second relay unit, a third relay unit, and a fourth relay unit;

[0007] Controlling each high-voltage component included in the high-voltage topology structure to perform a state self-check to determine that the fuel cell system is in a state that allows startup;

[0008] After receiving the start-up enable requirement fed back by the vehicle controller, controlling the fuel cell system to enter a start-up mode;

[0009] During the startup of the fuel cell system, controlling the heater to adjust the output voltage of the fuel cell stack, and then adjusting the operating state of the DCDC converter;

[0010] In combination with the current output voltage of the fuel cell stack and the current working states of the third relay unit and the fourth relay unit, checking the startup state of the fuel cell system;

[0011] The fuel cell stack is connected to the DCDC converter through the first relay unit, the DCDC converter is connected to the power battery through the second relay unit, the fuel cell stack is connected to the heater through the third relay unit, and the heater is connected to the DCDC converter through the fourth relay unit.

[0012] Furthermore, before controlling the fuel cell system to enter the startup mode, the method further includes:

[0013] When it is detected that the DC bus voltage of the DCDC converter is less than a preset voltage threshold, the second relay unit is controlled to be in a closed state.

[0014] Further, controlling the fuel cell system to enter a startup mode includes:

[0015] When the third relay unit is in a closed state and the fourth relay unit is in an open state, detecting whether the water inlet temperature and the water outlet temperature of the fuel cell stack meet a first predetermined temperature condition; if not, controlling the power of the heater to be reduced to 0 kW;

[0016] If so, the third relay unit is controlled to be in an open state and the fourth relay unit is controlled to be in a closed state, and at the same time, the thermal management system is controlled to heat the fuel cell stack until the water inlet temperature and the water outlet temperature of the fuel cell stack meet the second predetermined temperature condition, and then the power of the heater is controlled to be reduced to 0kW, and finally the fourth relay unit is controlled to be in an open state.

[0017] Furthermore, the thermal management system includes a circulating water pump and the heater.

[0018] Further, controlling the heater to adjust the output voltage of the fuel cell stack includes:

[0019] The heater is used to lower the output voltage of the fuel cell stack when the third relay unit is in a closed state, and the speed of the circulating water pump is adjusted in real time according to the water inlet temperature deviation of the fuel cell stack until it is detected that the output voltage of the fuel cell stack reaches a predetermined idle point voltage;

[0020] The first relay unit is controlled to be in a closed state, and then the power of the heater is controlled to be reduced to 0 kW within a predetermined time period.

[0021] Further, adjusting the operating state of the DCDC converter includes:

[0022] The load current of the DCDC converter is controlled to increase from 0A to a target current in an idling operation state within the predetermined time period.

[0023] Furthermore, the first relay unit includes a first pre-charging resistor, a first pre-charging relay and a first relay; the positive electrode of the fuel cell stack is connected to the positive input terminal of the DCDC converter through the first relay, and the first series circuit formed by the first pre-charging relay and the first pre-charging resistor is connected in parallel with the first relay.

[0024] Furthermore, the second relay unit includes a second pre-charging resistor, a second pre-charging relay and a second relay; the first positive output terminal of the DCDC converter is connected to the positive electrode of the power battery through the second relay, and the second series circuit formed by the second pre-charging relay and the second pre-charging resistor is connected in parallel with the second relay.

[0025] Furthermore, the third relay unit includes a third relay and a fourth relay; the positive electrode of the fuel cell stack is connected to the positive electrode of the heater through the third relay, and the negative electrode of the fuel cell stack is connected to the negative electrode of the heater through the fourth relay.

[0026] Furthermore, the fourth relay unit includes a fifth relay and a sixth relay; the second positive output terminal of the DCDC converter is connected to the positive electrode of the heater through the fifth relay, and the second negative output terminal of the DCDC converter is connected to the negative electrode of the heater through the sixth relay.

[0027] The present invention has at least the following beneficial effects: by connecting a heater in series with the fuel cell stack to act as a resistor, the output voltage of the fuel cell stack is quickly lowered according to the power adjustability of the heater until the final required idle point voltage is reached, thereby quickly reducing the high potential residence time of the fuel cell system during the startup process, thereby minimizing the damage to the proton exchange membrane and also helping to extend the service life of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0029] Figure 1 is a flow chart of a high-voltage side coordinated control method of a fuel cell system during startup in an embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of the composition of the high-voltage topological structure of the fuel cell system in an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of the composition of the thermal management system in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] It should be noted that, although the functional modules are divided in the system schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order from the module division in the system or the order in the flow chart. The terms "first", "second", "third", "fourth", etc. in the specification of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, such as processes, methods, systems, products or devices that include a series of steps or units, which are not necessarily limited to those steps or units clearly listed, but may include other steps or units inherent to these processes, methods, products or devices that are not clearly listed.

[0034] Please refer to Figure 1 , Figure 1 1 is a flow chart of a high-voltage side coordinated control method of a fuel cell system during startup provided by an embodiment of the present invention, the method comprising the following steps:

[0035] Step S100, building a high-voltage topology structure of a fuel cell system;

[0036] Step S200, controlling each high-voltage component included in the high-voltage topology structure to perform a state self-check to determine that the fuel cell system is in a state that allows startup;

[0037] Step S300, after receiving the startup enable requirement fed back by the vehicle controller, controlling the fuel cell system to enter the startup mode;

[0038] Step S400, during the startup process of the fuel cell system, controlling the heater to adjust the output voltage of the fuel cell stack, and then adjusting the operating state of the DCDC converter;

[0039] Step S500: Checking the startup state of the fuel cell system in combination with the current output voltage of the fuel cell stack and the current working states of the third relay unit and the fourth relay unit.

[0040] In the embodiment of the present invention, the high voltage topology structure constructed by the above step S100 is as follows: Figure 2 As shown, it specifically includes a fuel cell stack, a first relay unit, a DCDC converter, a second relay unit, a power battery, a third relay unit, a heater and a fourth relay unit; wherein the first relay unit is arranged on the power supply line between the fuel cell stack and the DCDC converter, and the second relay unit is arranged on the power supply line between the DCDC converter and the power battery; the third relay unit is arranged on the power supply line between the fuel cell stack and the heater, and the fourth relay unit is arranged on the power supply line between the DCDC converter and the heater.

[0041] Specifically, the first relay unit mainly includes a first relay K1, a first pre-charging relay K2 and a first pre-charging resistor R1. The positive electrode of the fuel cell stack is connected to the first end of the first relay K1, and the second end of the first relay K1 is connected to the positive input end of the DCDC converter. The first pre-charging resistor R1 is connected in series with the first pre-charging relay K2 to obtain a first series circuit. The first end of the first relay K1 is connected to one end of the first series circuit, and the second end of the first relay K1 is connected to the other end of the first series circuit. The negative electrode of the fuel cell stack is connected to the negative input end of the DCDC converter.

[0042] It should be noted that when the first relay unit is put into use to ensure normal connection between the fuel cell stack and the DCDC converter, it will preferentially control the first pre-charging relay K2 to be in a closed state, and then control the first relay K1 to be in a closed state after the current stabilizes. In addition, under the current limiting protection of the first pre-charging resistor R1, it can avoid excessive current in the connection line between the fuel cell stack and the DCDC converter, thereby causing electrical device ablation.

[0043] Specifically, the second relay unit mainly includes a second relay K3, a second pre-charging relay K4 and a second pre-charging resistor R2. The first positive output terminal of the DCDC converter is connected to the first end of the second relay K3, and the second end of the second relay K3 is connected to the positive electrode of the power battery. The second pre-charging resistor R2 is connected in series with the second pre-charging relay K4 to obtain a second series circuit. The first end of the second relay K3 is connected to one end of the second series circuit, and the second end of the second relay K3 is connected to the other end of the second series circuit. The first negative output terminal of the DCDC converter is connected to the negative electrode of the power battery.

[0044] It should be noted that when the second relay unit is put into use to ensure normal connection between the DCDC converter and the power battery, the second pre-charging relay K4 will be controlled to be in a closed state first, and the second relay K3 will be controlled to be in a closed state after the current stabilizes. In addition, under the current limiting protection of the second pre-charging resistor R2, it can be avoided that the connection line between the DCDC converter and the power battery generates excessive current, thereby causing ablation of electrical components.

[0045] Specifically, the third relay unit mainly includes a third relay K5, a fuse F1 and a fourth relay K6, the positive electrode of the fuel cell stack is connected to the first end of the third relay K5, the second end of the third relay K5 is connected to the positive electrode of the heater through the fuse F1, the negative electrode of the fuel cell stack is connected to the first end of the fourth relay K6, and the second end of the fourth relay K6 is connected to the negative electrode of the heater; wherein the fuse F1 plays a conventional line protection role.

[0046] It should be noted that when the third relay unit is put into use to ensure normal communication between the fuel cell stack and the heater, it is necessary to simultaneously control the third relay K5 and the fourth relay K6 to be in a closed state.

[0047] Specifically, the fourth relay unit mainly includes a fifth relay K7 and a sixth relay K8, the second positive output end of the DCDC converter is connected to the first end of the fifth relay K7, the second end of the fifth relay K7 is connected to the positive pole of the heater, the second negative output end of the DCDC converter is connected to the first end of the sixth relay K8, and the second end of the sixth relay K8 is connected to the negative pole of the heater.

[0048] It should be noted that when the fourth relay unit is put into use to ensure normal communication between the DCDC converter and the heater, it is necessary to simultaneously control the fifth relay K7 and the sixth relay K8 to be in a closed state.

[0049] In the embodiment of the present invention, the high-pressure topological structure may further include other high-pressure components such as an air compressor and a hydrogen circulation pump.

[0050] In an embodiment of the present invention, the high-voltage components provided in the high-voltage topology structure include a fuel cell stack, a heater and a DCDC converter, and a fuel cell controller, a heater controller and a DCDC controller are provided corresponding to each of the above-mentioned high-voltage components. The implementation process of the above-mentioned step S200 includes: when the fuel cell system receives a wake-up signal fed back by the vehicle controller through a hard-line wake-up method or a network wake-up method, the above-mentioned controllers are controlled to enter a wake-up state and perform a power-on self-test task, and only when the above-mentioned controllers are in a normal working state can the startup process of the fuel cell system be continued, so that the fuel cell system is currently in a startup-allowed state.

[0051] In the embodiment of the present invention, the specific implementation process of the above step S300 includes the following:

[0052] Step S310, controlling the third relay unit (i.e., the third relay K5 and the fourth relay K6) to be in a closed state, and also controlling the fourth relay unit (i.e., the fifth relay K7 and the sixth relay K8) to be in an open state;

[0053] Step S320, acquiring the water inlet temperature by a first temperature sensor disposed at the water inlet of the fuel cell stack, and acquiring the water outlet temperature by a second temperature sensor disposed at the water outlet of the fuel cell stack;

[0054] Step S330, judging whether the water inlet temperature is less than a first temperature threshold and whether the water outlet temperature is less than a second temperature threshold; if at least one of the above two conditions is not met, it means that the fuel cell system currently enters the normal temperature start mode, and at this time, it is only necessary to reduce the power of the heater to 0 kW through the heater controller; if the above two conditions are met at the same time, it means that the fuel cell system currently enters the cold start mode, and then continue to execute step S340;

[0055] Step S340, switching the third relay unit (i.e., the third relay K5 and the fourth relay K6) to an open state, and also switching the fourth relay unit (i.e., the fifth relay K7 and the sixth relay K8) to a closed state;

[0056] Step S350, using a thermal management system to perform a heating operation on the fuel cell stack, and during the entire heating process, collecting the current water inlet temperature of the fuel cell stack in real time through the first temperature sensor, and collecting the current water outlet temperature of the fuel cell stack in real time through the second temperature sensor;

[0057] Step S360, judging whether the current water inlet temperature collected in real time is greater than the third temperature threshold and whether the current water outlet temperature collected in real time is greater than the fourth temperature threshold; if the above two conditions are met at the same time, it means that the fuel cell system has currently switched from the cold start mode to the normal temperature start mode, and step S370 is executed; if at least one of the above two conditions is not met, it means that the fuel cell system is currently still in the cold start mode, and the process returns to step S350;

[0058] Step S370: lowering the power of the heater to 0 kW through the heater controller, and then controlling the fourth relay unit (ie, the fifth relay K7 and the sixth relay K8) to switch to an off state.

[0059] In the above step S350, the thermal management system mainly includes the heater, the circulating water pump, the radiator, the cooling fan, the expansion tank, the deionizer, the particle filter and the three-way solenoid valve. The connection relationship between the various components included in the thermal management system is as follows: Figure 3 As shown, when the thermal management system is used to perform the heating operation on the fuel cell stack, the heater and the circulating water pump are mainly controlled to operate in coordination.

[0060] In the above step S340, when the third relay unit (i.e., the third relay K5 and the fourth relay K6) is switched from a closed state to an open state, and at the same time, the fourth relay unit (i.e., the fifth relay K7 and the sixth relay K8) is switched from an open state to a closed state, the DCDC converter is used to provide electrical energy to the heater, so that the thermal management system can realize the heating operation of the fuel cell stack.

[0061] Since the fuel cell stack is not currently in the startup state, the DCDC converter can only be powered by the power battery. At this time, it is also necessary to ensure that the second relay unit (ie, the second relay K3 and the second pre-charging relay K4) is in the closed state.

[0062] In the above step S370, when the fourth relay unit (ie, the fifth relay K7 and the sixth relay K8) is switched to the disconnected state, it is also necessary to simultaneously control the first relay unit (ie, the first relay K1 and the first pre-charging relay K2) to switch to the disconnected state.

[0063] It should be noted that the first temperature threshold and the second temperature threshold mentioned in the above step S330 are both critical temperatures set in advance by technicians for the cold start conditions of the fuel cell system; the third temperature threshold and the fourth temperature threshold mentioned in the above step S360 are both critical temperatures set in advance by technicians for the normal temperature start conditions of the fuel cell system.

[0064] In the embodiment of the present invention, before controlling the fuel cell system to enter the startup mode, it is also necessary to preferentially adjust the output state of the DCDC converter, and the specific implementation process includes the following:

[0065] Step S1, determining whether the DC bus voltage of the DCDC converter is lower than a preset voltage threshold, where the preset voltage threshold is the maximum voltage value that the DCDC converter can reach within its boost capability range; if not, it means that the DC bus voltage currently exceeds the boost capability range of the DCDC converter, and step S2 is executed; if yes, it means that the DC bus voltage currently falls within the boost capability range of the DCDC converter, and step S3 is executed;

[0066] Step S2, controlling the second relay unit (i.e., the second relay K3 and the second pre-charging relay K4) to always remain in the disconnected state;

[0067] Step S3, controlling the second relay unit (ie, the second relay K3 and the second pre-charging relay K4) to switch to a closed state.

[0068] It should be noted that the start-up enable requirement sent by the vehicle controller is received and responded to by the fuel cell controller, but when the fuel cell controller does not receive the start-up enable requirement sent by the vehicle controller, it means that there is no need to start the fuel cell system at present, and the DCDC converter will remain in standby state, that is, there is no need to adjust the output state of the DCDC converter.

[0069] In the embodiment of the present invention, the specific implementation process of the above step S400 includes the following:

[0070] Step S410, controlling the third relay unit (i.e., the third relay K5 and the fourth relay K6) to be in a closed state to connect the high voltage connection between the heater and the fuel cell stack. At this time, the heater actually acts as a resistor and can lower the output voltage of the fuel cell stack;

[0071] Step S420, using the first temperature sensor to collect the current water inlet temperature of the fuel cell stack, then obtaining the target water inlet temperature of the fuel cell stack and performing a difference operation between the target water inlet temperature and the current water inlet temperature to obtain a water inlet temperature deviation;

[0072] Step S430, analyzing the water inlet temperature deviation by using a PID control method to obtain a control output value, and then adjusting the speed of the circulating water pump according to the control output value;

[0073] Step S440, obtaining the output voltage of the fuel cell stack and determining whether it reaches a predetermined idle point voltage; if so, proceeding to step S450; if not, returning to the above step S420;

[0074] Step S450, control the first relay unit (i.e., the first relay K1 and the first pre-charge relay K2) to switch to a closed state, and linearly reduce the power of the heater to 0 kW through the heater controller within a predetermined time period, and at the same time, increase the load current of the DCDC converter itself from an initial 0 A to a target current through the DCDC controller within the predetermined time period, wherein the target current is a current value basically required when the DCDC converter is in an idle operation state;

[0075] Step S460: after the predetermined time period has passed, the third relay unit (ie, the third relay K5 and the fourth relay K6) is switched to an open state, and the fourth relay unit (ie, the fifth relay K7 and the sixth relay K8) is switched to a closed state.

[0076] It should be noted that the power of the heater mentioned in the above step S450 can be determined according to the current boost ratio of the DCDC converter, and the current boost ratio is determined by the input terminal voltage and the output terminal voltage of the DCDC converter. The input terminal voltage refers to the port voltage when the DCDC converter is connected to the fuel cell stack, and the output terminal voltage refers to the port voltage when the DCDC converter is connected to the power battery.

[0077] In the embodiment of the present invention, the specific implementation process of the above step S500 includes the following:

[0078] Step S510, determining whether the current output voltage of the fuel cell stack still reaches the predetermined idle point voltage; if so, continuing to step S520; if not, directly outputting a prompt message indicating that the fuel cell system failed to start;

[0079] Step S520, determining whether the third relay unit (i.e., the third relay K5 and the fourth relay K6) is currently in a disconnected state; if so, proceeding to step S530; if not, directly outputting a prompt message indicating that the fuel cell system failed to start;

[0080] Step S530, determine whether the fourth relay unit (ie, the fifth relay K7 and the sixth relay K8) is in a closed state; if so, output a prompt message indicating that the fuel cell system is successfully started; if not, output a prompt message indicating that the fuel cell system fails to start.

[0081] It should be noted that the purpose of implementing the above step S510 is to ensure that after the above steps S450 to S460 are executed, there is not much impact on the current output voltage of the fuel cell stack.

[0082] In an embodiment of the present invention, a heater is connected in series with the fuel cell stack to act as a resistor, and the output voltage of the fuel cell stack is quickly lowered according to the power adjustability of the heater until the final required idle point voltage is reached. This can quickly reduce the high potential residence time of the fuel cell system during the startup process, thereby minimizing the damage to the proton exchange membrane and helping to extend the service life of the fuel cell stack.

[0083] In addition, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the high-voltage side collaborative control method of the fuel cell system in the startup process in the above embodiment is implemented. Wherein, the computer-readable storage medium includes but is not limited to any type of disk (including floppy disk, hard disk, optical disk, CD-ROM, and magneto-optical disk), ROM (Read-Only Memory), RAM (Random Access Memory), EPROM (EraSable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, magnetic card or optical card. In other words, the storage device includes any medium that stores or transmits information in a readable form by a device (such as a computer, a mobile phone, etc.), which can be a read-only memory, a disk or an optical disk, etc.

[0084] Although the description of the present application has been quite detailed and specifically describes several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the attached claims, taking into account the prior art, so as to effectively cover the intended scope of the present application. In addition, the above description of the present application is based on the embodiments foreseeable by the inventor, and its purpose is to provide a useful description, and those non-substantial changes to the present application that have not yet been foreseen may still represent equivalent changes to the present application.

Claims

1. A high-voltage side coordinated control method for a fuel cell system during startup, characterized in that: The method comprises: Building a high-voltage topology structure of a fuel cell system, which includes a fuel cell stack, a DCDC converter, a power battery, a heater, a first relay unit, a second relay unit, a third relay unit and a fourth relay unit, wherein the fuel cell stack is connected to the DCDC converter through the first relay unit, the DCDC converter is connected to the power battery through the second relay unit, the fuel cell stack is connected to the heater through the third relay unit, and the heater is connected to the DCDC converter through the fourth relay unit; Controlling each high-voltage component included in the high-voltage topology structure to perform a state self-check to determine that the fuel cell system is in a state that allows startup; After receiving the start-up enable requirement fed back by the vehicle controller, controlling the fuel cell system to enter a start-up mode; During the startup of the fuel cell system, controlling the heater to adjust the output voltage of the fuel cell stack, and then adjusting the operating state of the DCDC converter; In combination with the current output voltage of the fuel cell stack and the current working states of the third relay unit and the fourth relay unit, checking the startup state of the fuel cell system; Wherein, controlling the fuel cell system to enter a startup mode comprises: When the third relay unit is in a closed state and the fourth relay unit is in an open state, detecting whether the water inlet temperature and the water outlet temperature of the fuel cell stack meet a first predetermined temperature condition; if not, controlling the power of the heater to be reduced to 0 kW; If so, the third relay unit is controlled to be in an open state and the fourth relay unit is controlled to be in a closed state, and at the same time, the thermal management system is controlled to heat the fuel cell stack until the water inlet temperature and the water outlet temperature of the fuel cell stack meet the second predetermined temperature condition, the thermal management system includes a circulating water pump and the heater, and then the power of the heater is controlled to be reduced to 0kW, and finally the fourth relay unit is controlled to be in an open state; The step of controlling the heater to adjust the output voltage of the fuel cell stack and then adjusting the operating state of the DCDC converter includes: The heater is used to lower the output voltage of the fuel cell stack when the third relay unit is in a closed state, and the speed of the circulating water pump is adjusted in real time according to the water inlet temperature deviation of the fuel cell stack until it is detected that the output voltage of the fuel cell stack reaches a predetermined idle point voltage; The first relay unit is controlled to be in a closed state, and then the power of the heater is controlled to be reduced to 0 kW within a predetermined time period, and the load current of the DCDC converter is controlled to increase from 0 A to a target current in an idling state within the predetermined time period.

2. The high-voltage side coordinated control method of a fuel cell system during startup according to claim 1, characterized in that: Before controlling the fuel cell system to enter the startup mode, the method further includes: When it is detected that the DC bus voltage of the DCDC converter is less than a preset voltage threshold, the second relay unit is controlled to be in a closed state.

3. The high-voltage side coordinated control method of a fuel cell system during startup according to claim 1, characterized in that: The first relay unit includes a first pre-charging resistor, a first pre-charging relay and a first relay; the positive electrode of the fuel cell stack is connected to the positive input terminal of the DCDC converter through the first relay, and the first series circuit formed by the first pre-charging relay and the first pre-charging resistor is connected in parallel with the first relay.

4. The high-voltage side coordinated control method of a fuel cell system during startup according to claim 1, characterized in that: The second relay unit includes a second pre-charging resistor, a second pre-charging relay and a second relay; the first positive output terminal of the DCDC converter is connected to the positive electrode of the power battery through the second relay, and the second series circuit formed by the second pre-charging relay and the second pre-charging resistor is connected in parallel with the second relay.

5. The high-voltage side coordinated control method of a fuel cell system during startup according to claim 1, characterized in that: The third relay unit includes a third relay and a fourth relay; the positive electrode of the fuel cell stack is connected to the positive electrode of the heater through the third relay, and the negative electrode of the fuel cell stack is connected to the negative electrode of the heater through the fourth relay.

6. The high-voltage side coordinated control method of a fuel cell system during startup according to claim 1, characterized in that: The fourth relay unit includes a fifth relay and a sixth relay; the second positive output terminal of the DCDC converter is connected to the positive electrode of the heater through the fifth relay, and the second negative output terminal of the DCDC converter is connected to the negative electrode of the heater through the sixth relay.

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