Start-up operation assisting device for vehicle-mounted fuel cell and control method

Abstract

The application provides a starting operation auxiliary device of a vehicle-mounted fuel cell and belongs to the technical field of fuel cell power supply, and solves the problem of low-temperature starting limitation in the prior art. The device comprises a DC-DC booster, a bidirectional DC-DC converter, a super capacitor, a lithium battery and a controller. The power supply end of a fuel cell stack is connected with the input end of the lithium battery through the DC-DC booster, and is sequentially connected with the super capacitor through the DC-DC booster and the bidirectional DC-DC converter. The output end of the lithium battery is connected with a vehicle motor. The output end of the controller is connected with the control end of the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter and the super capacitor respectively. The function of fast low-temperature starting is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell power supply, in particular to a starting operation auxiliary device and control method of a vehicle-mounted fuel cell. BACKGROUND

[0002] A hydrogen fuel cell is a device that converts chemical energy in hydrogen fuel into electrical energy through an electrochemical reaction, and the product is only water, with the advantages of high efficiency, high reliability, low emission, and no pollution. The application scenarios of hydrogen fuel cells are very wide, among which, matching with a whole vehicle is an important trend in future development.

[0003] When running with a whole vehicle, the working condition environment of the whole vehicle needs to be considered, for example, when driving in a low-temperature environment, the performance of the power battery (lithium battery) is limited, and only discharge can be performed but not charging. When the whole vehicle is stopped, the whole vehicle cannot provide power to the fuel cell system, resulting in that the whole vehicle cannot be woken up to perform a re-blowing action on the stack after the motor is powered off. After stopping in a low-temperature environment, the temperature of the stack changes with time and the ambient temperature, which leads to the internal freezing of the stack without re-blowing. Therefore, it is very important to solve the problem of how the fuel cell can perform a heat preservation operation and a re-blowing action after stopping in a low-temperature environment when the whole vehicle cannot provide power.

[0004] At present, there is a lack of a device that can load a large power of a fuel cell stack when a vehicle is cold started in a low-temperature environment, and the lithium battery can be charged. SUMMARY

[0005] Embodiments of the present application aim to provide a starting operation auxiliary device of a vehicle-mounted fuel cell to solve the problem of limited low-temperature starting in the prior art.

[0006] In one aspect, the present application provides a starting operation auxiliary device of a vehicle-mounted fuel cell, comprising a DC-DC booster, a bidirectional DC-DC converter, a super capacitor, a lithium battery and a controller, wherein

[0007] The power supply end of the fuel cell stack is connected with the input end of the lithium battery through the DC-DC booster, and is sequentially connected with the super capacitor through the DC-DC booster and the bidirectional DC-DC converter; the output end of the lithium battery is connected with the motor of the whole vehicle; and the output end of the controller is connected with the control end of the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter and the super capacitor respectively.

[0008] The beneficial effects of the above technical solutions are as follows: although the power supply capability of the fuel cell stack is reduced in a low-temperature environment, the super capacitor can make up for the insufficient power of the fuel cell stack during vehicle driving in the low-temperature environment by setting the bidirectional DC-DC converter and the super capacitor; the super capacitor can normally supply power after the vehicle completes shutdown in the low-temperature environment, and the post parking purge (PPG) process is not affected; when cold starting in a low temperature, the lithium battery can be normally charged in a low temperature by the super capacitor to achieve the purpose of fast cold starting.

[0009] Based on the further improvement of the above device, the controller executes the following program:

[0010] Obtain the current running state of the vehicle motor and the real-time temperature of the fuel cell stack; the current running state is one of normal running, preparation for shutdown, shutdown state, and preparation for starting;

[0011] According to the real-time temperature of the fuel cell stack, in combination with the current running state of the vehicle motor, the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter, and the super capacitor are controlled to perform operations, so that the fuel cell stack supplies power and the super capacitor charges when normally running, the super capacitor is fully charged by the fuel cell stack when preparing to shut down, the super capacitor keeps the fuel cell stack warm at regular intervals when in the shutdown state, and the super capacitor supplies power to the fuel cell stack until the fuel cell stack cold starts when preparing to start.

[0012] The beneficial effects of the above further improvement scheme are that the super capacitor can provide energy to the stack during cold starting, which can ensure that the temperature of the fuel cell stack can be maintained above-20℃.

[0013] The controller further comprises, which are connected in sequence:

[0014] A data acquisition unit is configured to obtain the real-time speed of the vehicle motor, receive the vehicle motor control instruction input by a user, determine the current running state of the vehicle motor, obtain the real-time temperature and output current of the fuel cell stack, and send the current running state of the vehicle motor, the real-time temperature and output current of the fuel cell stack to the data processing and control unit;

[0015] A data processing and control unit is configured to send a control signal to an execution unit according to the received current running state of the vehicle motor in combination with the real-time temperature and output current of the fuel cell stack, so that the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter, and the super capacitor perform operations:

[0016] The execution unit is configured to control signal transmission in the DC-DC booster and the bidirectional DC-DC converter, power supply, charging or low-temperature storage of the fuel cell stack, and charging, power supply or disconnection of the super capacitor according to the received control signal.

[0017] The further improved scheme has the beneficial effect that the matching working logic sequence between the fuel cell stack and each component is realized through different data acquisition units combined with different control processes, so that the low-temperature operation process and the rapid low-temperature start can be ensured.

[0018] The data acquisition unit further comprises:

[0019] The speed sensor is arranged at the rotor of the vehicle motor and is configured to acquire the real-time rotating speed of the vehicle motor.

[0020] The temperature sensor is arranged inside the fuel cell stack and is configured to acquire the real-time temperature of the fuel cell stack.

[0021] The current sensor is arranged at the power supply output end of the fuel cell stack and is configured to acquire the output current of the fuel cell stack.

[0022] The instruction input button is configured to receive the vehicle motor control instruction input by the user.

[0023] The further improved scheme has the beneficial effect that the working state of the fuel cell can be determined, i.e., the current running state of the vehicle motor, through the acquisition of multiple types of data by different sensors.

[0024] The data processing and control unit executes the following program:

[0025] Acquire the current running state of the vehicle motor.

[0026] When the vehicle motor is running normally, control the fuel cell stack to charge the lithium battery through the DC-DC booster and to supply power to the vehicle motor, and simultaneously control the branch of the bidirectional DC-DC converter and the super capacitor to be disconnected.

[0027] When the vehicle motor is preparing to stop, control the fuel cell stack to charge the super capacitor through the DC-DC booster and the bidirectional DC-DC converter in sequence until the super capacitor is fully charged, and simultaneously control the branch of the lithium battery and the vehicle motor to be disconnected.

[0028] After the motor of the whole vehicle stops, the super capacitor is controlled to periodically heat the coolant in the fuel cell stack through the bidirectional DC-DC converter, so that the temperature of the stack is kept within a preset range, at the same time, the DC-DC booster and the branch in which the lithium battery is located are disconnected; after each heating is completed, the power of the super capacitor is detected, and once the power of the super capacitor is lower than the lower threshold, the super capacitor is controlled to stop heating, the DC-DC booster and the branch in which the lithium battery is located are connected, and the fuel cell stack is started to perform a parking purge operation, and the super capacitor is appropriately charged;

[0029] When the motor of the whole vehicle is ready to start, the super capacitor is controlled to heat the coolant in the fuel cell stack to a preset temperature through the bidirectional DC-DC converter, and then the fuel cell stack is powered until the output current of the fuel cell stack reaches a preset loadable current, then the bidirectional DC-DC converter and the branch in which the super capacitor is located are disconnected, and the fuel cell stack is controlled to charge the lithium battery through the DC-DC booster, and the motor of the whole vehicle is powered, and the cold start of the fuel cell stack is completed.

[0030] The beneficial effects of the above further improved scheme are: the program executed by the data processing and control unit is limited, and by judging different working states of the motor of the whole vehicle, the working states between the fuel cell stack, the super capacitor, the DC-DC components (DC-DC booster, bidirectional DC-DC converter) are further switched, so that the cold start of the stack is completed;

[0031] The execution unit further comprises:

[0032] A plurality of MOS switches are respectively arranged at the front ends of the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the super capacitor and the thermistor, and are used to control the transmission of electrical signals of the branches in which the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the super capacitor and the thermistor are located; the front end refers to the side close to the fuel cell stack;

[0033] The thermistor is arranged inside the fuel cell stack, and the input end is connected with the bidirectional DC-DC converter through the MOS switch, and is used to heat the coolant in the fuel cell stack.

[0034] The beneficial effects of the above further improved scheme are: by matching between the super capacitor and the bidirectional DC-DC, the control of the thermistor (PTC) in the stack is realized, and then the coolant is heated;

[0035] When the motor of the whole vehicle is running normally, the data processing and control unit executes the following program:

[0036] Respectively control the MOS switch in front of the DC-DC booster, lithium battery, thermistor, bidirectional DC-DC converter and super capacitor, so that the fuel cell stack is boosted by the DC-DC booster to a preset multiple of voltage, then the lithium battery is quickly charged, and the vehicle motor is powered;

[0037] When the vehicle motor is ready to stop, the data processing and control unit executes the following program:

[0038] Identify whether the super capacitor is fully charged, if yes, open the MOS switch in front of the DC-DC booster, bidirectional DC-DC converter, lithium battery, super capacitor and thermistor, otherwise, execute the next step.

[0039] Control the MOS switch in front of the DC-DC booster, bidirectional DC-DC converter and super capacitor to be closed, and the MOS switch in front of the thermistor and lithium battery to be opened, so that the fuel cell is sequentially charged to the super capacitor through the DC-DC booster and bidirectional DC-DC converter, and when the super capacitor is fully charged, the MOS switch in front of the DC-DC booster, bidirectional DC-DC converter and super capacitor is opened.

[0040] The beneficial effect of the above further improved scheme is that the charging and discharging process of the super capacitor is realized by setting the MOS switch in front of the super capacitor.

[0041] When the vehicle motor is stopped, the data processing and control unit executes the following program:

[0042] Every preset time, control the MOS switch in front of the bidirectional DC-DC converter, super capacitor and thermistor to be closed, and the MOS switch in front of the DC-DC booster and lithium battery to be opened, so that the super capacitor periodically heats the cooling liquid in the fuel cell stack through the bidirectional DC-DC converter, so that the stack temperature is maintained within a preset range.

[0043] After each heating is completed, the SOC of the super capacitor is monitored in real time, and once the SOC of the super capacitor reaches the lower threshold, the MOS switch in front of the thermistor is opened, and the above periodic heating is no longer performed. Then, the MOS switch in front of the DC-DC booster and lithium battery is closed, and the fuel cell stack is started to perform a parking purge operation.

[0044] During the above purge operation, the voltage and resistance value of each single piece in the stack are detected in real time, and when the resistance value of each single piece in the stack reaches the target value, the purge operation is stopped, and the super capacitor is charged with an appropriate amount of charge Q.

[0045] Q=(I*V-P bop)*t

[0046] In the formula, I is the current of the stack load during purging, in A; V is the total voltage of the stack during purging, in V; P is the consumed power of the fuel cell, in kw; t is the purging time, in h; bop

[0047] After the charging is completed, the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the super capacitor and the MOS switch in front of the thermistor are all turned off.

[0048] The beneficial effect of the further improved scheme is that the super capacitor can realize the heat preservation and purging of the stack, and the super capacitor can be supplemented with power after the stack is further started;

[0049] When the motor of the whole vehicle is ready to start, the data processing and control unit executes the following program:

[0050] The MOS switch in front of the bidirectional DC-DC converter, the super capacitor and the thermistor is turned on, and the MOS switch in front of the DC-DC booster and the lithium battery is turned off, so that the super capacitor heats the cooling liquid in the fuel cell stack through the bidirectional DC-DC converter;

[0051] During the above heating process, the real-time temperature of the fuel cell stack is obtained, and the real-time temperature is compared with the preset temperature, and once the preset temperature is reached, the MOS switch in front of the thermistor is turned on to stop heating, and at the same time, the MOS switch in front of the DC-DC booster and the lithium battery is turned on, so that the super capacitor supplies power to the fuel cell stack in reverse;

[0052] During the above reverse power supply process, the output current of the fuel cell stack is obtained, until the output current of the fuel cell stack reaches the preset loadable current, the MOS switch in front of the bidirectional DC-DC converter and the super capacitor is turned off, so that the fuel cell stack charges the lithium battery through the DC-DC booster, and supplies power to the motor of the whole vehicle, and completes the cold start of the fuel cell stack.

[0053] The beneficial effect of the further improved scheme is that the power generated by the super capacitor during the cold start of the fuel cell can charge the lithium battery, thereby avoiding the problem that the lithium battery cannot be charged at low temperature.

[0054] On the other hand, the embodiment of the present application provides a kind of starting operation control method of vehicle-mounted fuel cell, comprising the following steps:

[0055] Obtain the current running state of the motor of the whole vehicle;

[0056] ​If in normal operation state, identify whether the parking instruction of the whole vehicle is received; if not, control the fuel cell stack to charge the super capacitor through the DC-DC booster, and at the same time, supply power to the motor of the whole vehicle; if the parking instruction is received, detect the residual power in the super capacitor, if not full, charge the super capacitor through the DC-DC booster and the bidirectional DC-DC converter until the super capacitor is full of power, and then shut down the whole vehicle;

[0057] If in the parking state, identify whether the start instruction of the whole vehicle is received; if not, detect the stack temperature regularly, if the stack temperature exceeds the lower threshold, control the super capacitor to heat and keep warm for the stack until the power of the super capacitor reaches the lower threshold, stop heating and keeping warm, and control the fuel cell stack to supply power to execute the parking purge; if the start instruction is received, control the super capacitor to lift the fuel cell stack cooling liquid to the preset temperature, and then supply power to the fuel cell stack until the cold start of the fuel cell stack is completed.

[0058] The beneficial effects of the above scheme are: although the power supply capacity of the fuel cell stack decreases in the low temperature environment, the bidirectional DC-DC converter and the super capacitor are set to make the super capacitor compensate for the insufficient power of the fuel cell stack in the low temperature environment; after the whole vehicle completes parking in the low temperature environment, the super capacitor can supply power normally, and the later parking purge (PPG) process is not affected; when the low temperature cold start is performed, the super capacitor can pull a large power, and the lithium battery can still be charged normally in the low temperature, so as to achieve the purpose of fast low temperature start.

[0059] The summary section is provided to introduce a selection of concepts in a simplified form, which will be further described below in the detailed description. The summary section is not intended to identify key or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0060] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the figures, in which exemplary embodiments of the present disclosure are shown.

[0061] Figure 1 A structure schematic diagram of the start-up and operation auxiliary device of the vehicle-mounted fuel cell of embodiment 1 is shown;

[0062] Figure 2 A circuit connection schematic diagram of the start-up and operation auxiliary device of the vehicle-mounted fuel cell of embodiment 1 is shown;

[0063] Figure 3 A structure schematic diagram of the start-up and operation auxiliary device of the vehicle-mounted fuel cell of embodiment 2 is shown;

[0064] Figure 4 The SOC power change of the supercapacitor of Example 2 is shown;

[0065] Figure 5 The low-temperature start instance schematic diagram of Example 2 is shown.

[0066] Reference signs:

[0067] V+ - positive electrode of the fuel cell stack; V- - negative electrode of the fuel cell stack;

[0068] Time - time; MOS switch 1 - MOS switch in front of the DC-DC booster;

[0069] MOS switch 2 - MOS switch in front of the bidirectional DC-DC converter;

[0070] MOS switch 3 - MOS switch in front of the lithium battery;

[0071] MOS switch 4 - MOS switch in front of the supercapacitor. DETAILED DESCRIPTION

[0072] Embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure is more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0073] The term "comprising" and variations thereof as used herein are intended to mean "including but not limited to". The term "or" as used herein is intended to mean "and / or". The term "based on" means "based, at least in part, on". The terms "one example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. can refer to different or same objects. Other explicit and implicit definitions can also be included below.

[0074] Example 1

[0075] One embodiment of the present application provides a start-up running auxiliary device for a vehicle-mounted fuel cell, as shown in Figures 1-2 including a DC-DC booster, a bidirectional DC-DC converter, a supercapacitor, a lithium battery and a controller.

[0076] The power supply end of the fuel cell stack is connected with the input end of the lithium battery through a DC-DC booster, and is sequentially connected with the super capacitor through the DC-DC booster and the bidirectional DC-DC converter; the output end of the lithium battery is connected with the motor of the whole vehicle; and the output end of the controller is connected with the control end of the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter and the super capacitor.

[0077] The DC-DC booster is used to lift the voltage platform output by the fuel cell stack to the voltage platform that the lithium battery can be charged at when the fuel cell stack is normally operated, and the voltage platform can be lifted by 6 times, for example, to 600V, so that the charging speed is accelerated. The DC-DC booster has a disturbance function for the fuel cell voltage.

[0078] The bidirectional DC-DC converter is used for bidirectional flow of the direct current energy for charging and discharging the super capacitor.

[0079] The super capacitor is used for charging when the motor of the whole vehicle is ready to stop, periodically discharging to heat and keep the fuel cell stack after stopping, and charging the fuel cell stack after the fuel cell stack is heated to a preset temperature until the output current of the fuel cell reaches the loadable current to realize cold start success.

[0080] The lithium battery is used for charging when the fuel cell stack is normally operated, and maintaining the preset voltage for the operation of the motor of the whole vehicle.

[0081] The controller is used for controlling the on-off and signal transmission direction of the DC-DC booster and the bidirectional DC-DC converter, and controlling the charging and discharging of the super capacitor and the lithium battery.

[0082] Compared with the prior art, although the power supply capacity of the fuel cell stack is reduced in the low temperature environment, the super capacitor can make up for the shortage of the fuel cell power in the low temperature environment through the bidirectional DC-DC converter and the super capacitor; the super capacitor can normally supply power after the whole vehicle is stopped in the low temperature environment, and the post parking purge (PPG) process is not affected; and the lithium battery can be normally charged in the low temperature through the super capacitor to load high power, so that the purpose of fast low temperature start is achieved.

[0083] Embodiment 2

[0084] The controller executes the following program based on the optimization of embodiment 1.

[0085] S1. Obtain the current running state of the motor of the whole vehicle and the real-time temperature of the fuel cell stack; the current running state is one of normal operation, preparation for stopping, stopping state and preparation for starting;

[0086] S2. According to the real-time temperature of the fuel cell stack, combined with the current operating state of the vehicle motor, control the fuel cell stack, DC-DC booster, bidirectional DC-DC converter, super capacitor to perform operations: so that the fuel cell stack supplies power during normal operation, the super capacitor is fully charged when the fuel cell stack is shut down, the super capacitor is used to keep the fuel cell stack warm during the shutdown state, and the super capacitor supplies power to the fuel cell stack until the fuel cell stack is started.

[0087] Specifically, if the speed of the vehicle motor is not 0, identify whether a vehicle parking instruction is received; if not received (step S21), it is in a normal operating state; if received (step S22), it is in a state of preparing to stop; if the speed of the vehicle motor is 0, identify whether a vehicle start instruction is received; if not received (step S23), it is in a shutdown state; if received (step S24), it is in a state of preparing to start.

[0088] Preferably, the controller further comprises a data acquisition unit, a data processing and control unit, and an execution unit connected in sequence, as shown in Figure 3 .

[0089] The data acquisition unit is used to obtain the real-time speed of the vehicle motor and receive the user input vehicle motor control instruction to determine the current operating state of the vehicle motor; and obtain the real-time temperature and output current of the fuel cell stack; and send the current operating state of the vehicle motor, the real-time temperature and output current of the fuel cell stack to the data processing and control unit.

[0090] Preferably, the data acquisition unit further comprises a speed sensor, a temperature sensor, a current sensor, and an instruction control button. The speed sensor is arranged at the rotor of the vehicle motor to obtain the real-time speed of the vehicle motor. The temperature sensor is arranged inside the fuel cell stack to obtain the real-time temperature of the fuel cell stack. The current sensor is arranged at the power supply output end of the fuel cell stack to obtain the output current of the fuel cell stack. The instruction input button is used to receive the user input vehicle motor control instruction.

[0091] The data processing and control unit is used to send a control signal to the execution unit according to the received current operating state of the vehicle motor, combined with the real-time temperature and output current of the fuel cell stack: so that the fuel cell stack, DC-DC booster, bidirectional DC-DC converter, super capacitor perform operations:

[0092] The execution unit is configured to control signal transmission in the DC-DC booster and the bidirectional DC-DC converter, power supply, charging or low-temperature storage of the fuel cell stack, and charging, power supply or disconnection of the supercapacitor according to the received control signal.

[0093] Preferably, the execution unit further comprises a plurality of MOS switches and a thermistor. The plurality of MOS switches are respectively arranged at the front ends of the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the supercapacitor and the thermistor, and are configured to control electrical signal transmission of the branches in which the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the supercapacitor and the thermistor are located. The thermistor is arranged in the fuel cell stack, and an input end thereof is connected to the bidirectional DC-DC converter through a MOS switch, and is configured to heat the coolant in the fuel cell stack.

[0094] Preferably, the device further comprises a fuel cell inspection module. The fuel cell inspection module is configured to detect the internal resistance value of each single piece in the stack, and refer to patent CN202020941200.8. The fuel cell inspection module is configured to monitor the internal resistance of each single piece in the stack, and stop the purging operation when the internal resistance of each single piece in the stack reaches a preset target value.

[0095] Preferably, the data processing and control unit executes the following program, that is, step S2 is further refined as:

[0096] S21. When the motor of the whole vehicle is normally operating, the fuel cell stack is controlled to charge the lithium battery through the DC-DC booster, and the motor of the whole vehicle is supplied with power, and at the same time, the branch in which the bidirectional DC-DC converter and the supercapacitor are located is disconnected;

[0097] S22. When the motor of the whole vehicle is preparing to stop, the fuel cell is controlled to sequentially charge the supercapacitor through the DC-DC booster and the bidirectional DC-DC converter, until the supercapacitor is fully charged, and at the same time, the branch in which the lithium battery and the motor of the whole vehicle are located is disconnected;

[0098] S23. After the motor of the whole vehicle is stopped, the supercapacitor is controlled to periodically heat the coolant in the fuel cell stack through the bidirectional DC-DC converter, so that the temperature of the stack is kept within a preset range, and at the same time, the branch in which the DC-DC booster and the lithium battery are located is disconnected; after each heating is completed, the electric quantity of the supercapacitor is detected, and once the electric quantity of the supercapacitor is lower than a lower threshold value, the supercapacitor is controlled to stop heating, the branch in which the DC-DC booster and the lithium battery are located is connected, and the fuel cell stack is started to perform a parking purging operation, and the supercapacitor is appropriately charged;

[0099] S24. When the vehicle motor is ready to start, control the super capacitor to heat the cooling liquid in the fuel cell stack through the bidirectional DC-DC converter to a preset temperature, then supply power to the fuel cell stack until the output current of the fuel cell stack reaches the preset loadable current, then control the bidirectional DC-DC converter and the branch of the super capacitor to be disconnected, control the fuel cell stack to charge the lithium battery through the DC-DC booster, and supply power to the vehicle motor, completing the cold start of the fuel cell stack.

[0100] Preferably, step S21 is further refined as:

[0101] S211. Control the DC-DC booster, the MOS switch at the front end of the lithium battery, the MOS switch at the front end of the bidirectional DC-DC converter and the super capacitor to be closed and opened respectively, so that the fuel cell stack boosts the voltage by a preset multiple through the DC-DC booster, then quickly charges the lithium battery, and supplies power to the vehicle motor.

[0102] At this time, the output power of the fuel cell = lithium battery capacity * 80% - lithium battery remaining capacity + vehicle motor power consumption.

[0103] Preferably, step S22 is further refined as:

[0104] S221. Identify whether the SOC of the super capacitor is full, if it is full, open all the MOS switches at the front end of the DC-DC booster, bidirectional DC-DC converter, lithium battery, super capacitor and thermistor, otherwise, execute the next step;

[0105] S222. Control the MOS switches at the front end of the DC-DC booster, bidirectional DC-DC converter and super capacitor to be closed, and the MOS switches at the front end of the thermistor and lithium battery to be opened, so that the fuel cell charges the super capacitor through the DC-DC booster and bidirectional DC-DC converter in turn, and when the SOC of the super capacitor is full, open the MOS switches at the front end of the DC-DC booster, bidirectional DC-DC converter and super capacitor. That is, the fuel cell system is shut down.

[0106] Preferably, step S23 is further refined as:

[0107] S231. Every preset time (1 h apart within 4 h of shutdown, 30 min apart after 4 h of shutdown), control the MOS switches at the front end of the bidirectional DC-DC converter, super capacitor and thermistor to be closed, and the MOS switches at the front end of the DC-DC booster and lithium battery to be disconnected, so that the super capacitor periodically heats the cooling liquid in the fuel cell stack through the bidirectional DC-DC converter, so that the stack temperature is maintained within a preset range (not lower than -20℃);

[0108] S232. After each heating, the SOC of the supercapacitor is monitored in real time. Once the SOC of the supercapacitor reaches a lower threshold value (exemplarily, 40%), the MOS switch at the front end of the thermistor is controlled to be opened, the periodic heating described above is stopped, the MOS switch at the front end of the DC-DC booster and the lithium battery is controlled to be closed, and the fuel cell stack is started to perform a parking purge operation (i.e., the air and hydrogen systems of the fuel cell system start to work to purge the hydrogen and air of the stack);

[0109] S233. During the above-mentioned purge operation, the voltage and resistance of each single piece in the stack are detected in real time. When the resistance of each single piece in the stack reaches a target value, the purge operation is stopped, and the supercapacitor is charged with an appropriate amount of electricity Q, which is

[0110] Q = (I * V - P bop ) * t

[0111] wherein I is the current drawn by the stack during the purge, in A; V is the total voltage of the stack during the purge, in V; P bop is the power consumption of the fuel cell, in kw; and t is the purge time, in h. Since the fuel cell generates heat and electricity during the purge, the temperature of the supercapacitor and the stack will rise.

[0112] S234. After the charging is completed, the MOS switches at the front ends of the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the supercapacitor, and the thermistor are all controlled to be opened.

[0113] Preferably, step S24 is further refined as:

[0114] S241. The MOS switches at the front ends of the bidirectional DC-DC converter, the supercapacitor, and the thermistor are controlled to be closed, and the MOS switches at the front ends of the DC-DC booster and the lithium battery are controlled to be opened, so that the supercapacitor heats the cooling liquid in the fuel cell stack through the bidirectional DC-DC converter;

[0115] S242. During the above-mentioned heating, the real-time temperature of the fuel cell stack is obtained, and the real-time temperature is compared with a preset temperature (5℃). Once the preset temperature is reached, the MOS switch at the front end of the thermistor is controlled to be opened to stop the heating, and the MOS switches at the front ends of the DC-DC booster and the lithium battery are controlled to be closed, so that the supercapacitor supplies power to the fuel cell stack in reverse;

[0116] S243. In the above reverse power supply process, the output current of the fuel cell stack is obtained until the output current of the fuel cell stack reaches the preset loadable current, the MOS switch in front of the super capacitor is controlled to be turned off, so that the fuel cell stack charges the lithium battery through the DC-DC booster and supplies power to the vehicle motor, and the cold start of the fuel cell stack is completed;

[0117] S244. After the cold start is completed, the fuel cell stack is controlled to charge the super capacitor until the SOC of the super capacitor reaches 95%, and the output power is output according to the demand power of the vehicle motor.

[0118] During the steps S21-S24, the SOC of the super capacitor changes as shown in Figure 4 , and the example flow is as shown in Figure 5 .

[0119] Compared with embodiment 1, the device provided in the embodiment obtains the real-time temperature of the fuel cell stack through a temperature sensor, and combines the current running state (i.e. one of normal running, preparation for shutdown, shutdown state, and preparation for start) of the vehicle motor obtained through a speed sensor and an instruction input module to control the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter, and the super capacitor to perform operations, so that the fuel cell stack supplies power and the super capacitor charges when the vehicle is normally running, the super capacitor is fully charged by the fuel cell stack when the vehicle is preparing to shut down, the super capacitor keeps the fuel cell stack warm at regular intervals when the vehicle is in a shutdown state, and the super capacitor supplies power to the fuel cell stack until the cold start of the fuel cell stack is completed when the vehicle is preparing to start.

[0120] Embodiment 3

[0121] The application also provides a low-temperature start control method of a vehicle-mounted fuel cell corresponding to the device in embodiments 1 or 2, which comprises the following steps:

[0122] S1. Obtain the current running state of the vehicle motor;

[0123] S2*. If the vehicle is in a normal running state, it is identified whether a shutdown instruction of the vehicle is received; if not (step S21), the fuel cell stack is controlled to charge the super capacitor through the DC-DC booster, and at the same time, the vehicle motor is supplied with power; if the shutdown instruction is received (step S22), the remaining electric quantity in the super capacitor is detected, and if the super capacitor is not fully charged, the super capacitor is charged through the DC-DC booster and the bidirectional DC-DC converter until the super capacitor is fully charged, and then the vehicle is shut down.

[0124] S2**. If in the parking state, identify whether a start instruction of the whole vehicle is received; if not received (step S23), the stack temperature is detected, if the stack temperature exceeds the lower threshold value, the super capacitor is controlled to heat the stack, and the super capacitor is heated and kept until the electric quantity of the super capacitor reaches the lower threshold value, the heating and keeping is stopped, and the fuel cell stack is controlled to supply power to execute the parking purge; if received (step S24), the super capacitor is controlled to lift the fuel cell stack cooling liquid to a preset temperature, and then supply power to the fuel cell stack until the cold start of the fuel cell stack is completed.

[0125] Embodiments of the present disclosure have been described above, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application, or improvement of the prior art of the embodiments, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.

Claims

1. A start-up and operation auxiliary device for an on-board fuel cell, characterized in that, The controller comprises a DC-DC booster, a bidirectional DC-DC converter, a super capacitor, a lithium battery and a controller. The power supply end of the fuel cell stack is connected with the input end of the lithium battery through the DC-DC booster, and is sequentially connected with the super capacitor through the DC-DC booster and the bidirectional DC-DC converter. The controller executes the following program: The current running state of the vehicle motor and the real-time temperature of the fuel cell stack are obtained. According to the real-time temperature of the fuel cell stack and the current running state of the vehicle motor, the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter and the super capacitor are controlled to perform the following operations: when the vehicle motor is normally running, the fuel cell stack supplies power and the super capacitor is charged; when the vehicle motor is preparing to stop, the fuel cell stack fully charges the super capacitor; when the vehicle motor is in a stop state, the super capacitor periodically keeps the fuel cell stack warm; and when the vehicle motor is preparing to start, the super capacitor supplies power to the fuel cell stack until the fuel cell stack is cold started. The controller further comprises the following components connected in sequence: A data acquisition unit is configured to obtain the real-time speed of the vehicle motor, receive the vehicle motor control instruction input by a user, determine the current running state of the vehicle motor, obtain the real-time temperature and output current of the fuel cell stack, and send the current running state of the vehicle motor, the real-time temperature and output current of the fuel cell stack to a data processing and control unit. The data processing and control unit is configured to send a control signal to an execution unit according to the current running state of the vehicle motor, the real-time temperature and output current of the fuel cell stack, so that the fuel cell stack, the DC-DC booster, the bidirectional DC-DC converter and the super capacitor perform the following operations: The data acquisition unit further comprises: A speed sensor arranged at the rotor of the vehicle motor and configured to obtain the real-time speed of the vehicle motor. A temperature sensor arranged inside the fuel cell stack and configured to obtain the real-time temperature of the fuel cell stack. A current sensor arranged at the power supply output end of the fuel cell stack and configured to obtain the output current of the fuel cell stack. An instruction input button configured to receive the vehicle motor control instruction input by the user. The data processing and control unit executes the following program: The current running state of the vehicle motor is obtained. When the vehicle motor is normally running, the fuel cell stack is controlled to charge the lithium battery through the DC-DC booster and supply power to the vehicle motor, and the branch of the bidirectional DC-DC converter and the super capacitor is controlled to be disconnected. When the motor of the whole vehicle is preparing to stop, the fuel cell is controlled to be charged to the super capacitor through the DC-DC booster and the bidirectional DC-DC converter in turn until the super capacitor is fully charged, and meanwhile, the branch of the lithium battery and the motor of the whole vehicle is controlled to be disconnected; After the motor of the whole vehicle is stopped, the super capacitor is controlled to periodically heat the cooling liquid in the fuel cell stack through the bidirectional DC-DC converter, so that the temperature of the stack is kept within a preset range, and meanwhile, the branch of the DC-DC booster and the lithium battery is controlled to be disconnected; after each heating is completed, the electric quantity of the super capacitor is detected, and once the electric quantity of the super capacitor is lower than a lower threshold, the super capacitor is controlled to stop heating, the branch of the DC-DC booster and the lithium battery is controlled to be connected, and the fuel cell stack is controlled to perform a parking purge operation and charge the super capacitor; When the motor of the whole vehicle is preparing to start, the super capacitor is controlled to heat the cooling liquid in the fuel cell stack to a preset temperature through the bidirectional DC-DC converter, then the fuel cell stack is powered until the output current of the fuel cell stack reaches a preset loadable current, then the branch of the bidirectional DC-DC converter and the super capacitor is controlled to be disconnected, and the fuel cell stack is controlled to charge the lithium battery through the DC-DC booster and power the motor of the whole vehicle, so as to complete the cold start of the fuel cell stack; The execution unit further comprises: a plurality of MOS switches respectively arranged at the front ends of the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the super capacitor and the thermistor, and used for controlling the transmission of the electric signal of the branch of the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the super capacitor and the thermistor; the front end refers to the side close to the fuel cell stack; The thermistor is arranged in the fuel cell stack, and the input end is connected with the bidirectional DC-DC converter through the MOS switch, and used for heating the cooling liquid in the fuel cell stack; When the motor of the whole vehicle is normally running, the data processing and control unit executes the following program: The MOS switches at the front ends of the DC-DC booster and the lithium battery are controlled to be closed, and the MOS switches at the front ends of the thermistor, the bidirectional DC-DC converter and the super capacitor are controlled to be opened, so that the fuel cell stack is powered after the voltage is boosted by a preset multiple through the DC-DC booster, the lithium battery is rapidly charged, and the motor of the whole vehicle is powered; When the motor of the whole vehicle is preparing to stop, the data processing and control unit executes the following program: It is identified whether the super capacitor is fully charged, if yes, the MOS switches at the front ends of the DC-DC booster, the bidirectional DC-DC converter, the lithium battery, the super capacitor and the thermistor are all controlled to be opened, otherwise, the next step is executed; The MOS switches at the front ends of the DC-DC booster, the bidirectional DC-DC converter and the super capacitor are controlled to be closed, and the MOS switches at the front ends of the thermistor and the lithium battery are controlled to be opened, so that the fuel cell is charged to the super capacitor through the DC-DC booster and the bidirectional DC-DC converter in turn until the super capacitor is fully charged, and then the MOS switches at the front ends of the DC-DC booster, the bidirectional DC-DC converter and the super capacitor are opened; When the motor of the whole vehicle is stopped, the data processing and control unit executes the following program: Every preset time, the MOS switch in front of the super capacitor, the thermistor and the bidirectional DC-DC converter is closed, and the MOS switch in front of the DC-DC booster and the lithium battery is opened, so that the super capacitor periodically heats the coolant in the fuel cell stack through the bidirectional DC-DC converter, and the temperature of the stack is kept within the preset range; After each heating, the SOC of the super capacitor is monitored in real time, and once the SOC of the super capacitor reaches the lower threshold, the MOS switch in front of the thermistor is opened, and the periodic heating is stopped. Then, the MOS switch in front of the DC-DC booster and the lithium battery is closed, and the fuel cell stack is started to perform the parking purge operation; During the above purge operation, the voltage and resistance value of each single piece in the stack are detected in real time, and when the resistance of each single piece in the stack reaches the target value, the purge operation is stopped, and the super capacitor is charged appropriately. The charging capacity Q is Q = (I*V - P bop )*t In the formula, I is the current of the stack load during purging, in A; V is the total voltage of the stack during purging, in V; P bop P is the consumed power of the fuel cell, in kw; t is the purging time, in h; After charging, the MOS switches in front of the DC-DC booster, bidirectional DC-DC converter, lithium battery, super capacitor and thermistor are all turned off. When the motor of the whole vehicle is ready to start, the data processing and control unit executes the following program: The MOS switch in front of the super capacitor, the thermistor and the bidirectional DC-DC converter is closed, and the MOS switch in front of the DC-DC booster and the lithium battery is opened, so that the super capacitor heats the coolant in the fuel cell stack through the bidirectional DC-DC converter; During the above heating, the real-time temperature of the fuel cell stack is obtained, and the real-time temperature is compared with the preset temperature. Once the preset temperature is reached, the MOS switch in front of the thermistor is opened to stop heating, and the MOS switch in front of the DC-DC booster and the lithium battery is closed to make the super capacitor supply power to the fuel cell stack in reverse; During the above reverse power supply, the output current of the fuel cell stack is obtained until the output current of the fuel cell stack reaches the preset loadable current, the MOS switch in front of the bidirectional DC-DC converter and the super capacitor is turned off, so that the fuel cell stack charges the lithium battery through the DC-DC booster, and supplies power to the motor of the whole vehicle, completing the cold start of the fuel cell stack; The starting and running control method of the vehicle-mounted fuel cell comprises the following steps: Obtain the current running state of the motor of the whole vehicle; If in normal running state, identify whether a parking instruction of the whole vehicle is received; if not, control the fuel cell stack to charge the super capacitor through the DC-DC booster, and at the same time, supply power to the motor of the whole vehicle; if received, detect the remaining capacity in the super capacitor, and if not full, charge the super capacitor through the DC-DC booster and the bidirectional DC-DC converter until the capacity of the super capacitor is full, and shut down the whole vehicle; If in the parking state, identify whether a start instruction of the whole vehicle is received; if not, detect the temperature of the electric pile in a time manner, if the temperature of the electric pile exceeds a lower threshold value, control the super capacitor to heat and keep warm the electric pile until the electric quantity of the super capacitor reaches the lower threshold value, stop heating and keeping warm, and control the fuel cell electric pile to supply power to execute parking purging; if the start instruction is received, control the super capacitor to lift the fuel cell electric pile cooling liquid to a preset temperature, and then supply power to the fuel cell electric pile until the cold start of the fuel cell electric pile is completed.

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