A thermal management method, circuit and device for a fuel cell system

Abstract

The present invention discloses a thermal management method, circuit and device for a fuel cell system, and relates to the technical field of thermal management of fuel cells. The present invention solves the required coolant flow rate, and then obtains the coolant deviation in combination with the current coolant flow rate, thereby realizing the speed adjustment of each water pump in the cooling box. The present invention detects the real-time cooling box temperature and solves the required speed of each water pump in the cooling box, so that multiple water pumps can be adjusted in time based on the actual temperature of the fuel cell, and the local temperature of the fuel cell is regulated while ensuring that the overall temperature of the fuel cell meets the standard, thereby ensuring the uniformity of the fuel cell; through the adjustment of multiple water pumps, the accuracy of temperature control is improved, and accurate thermal management of the fuel cell is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell thermal management, and in particular to a thermal management method, circuit and device for a fuel cell system. Background Art

[0002] With the development of society, the number of cars on the market is increasing day by day, and the thermal management of automotive fuel cells has become a crucial issue in the development of automobiles. Due to the irreversibility of the electrochemical conversion of hydrogen in fuel cells, heat is generated as a byproduct. Heat will affect the operation of the fuel cell. If the temperature of the fuel cell is too high, it will affect the life and stability of the fuel cell. If the temperature of the fuel cell is too low, it will affect the normal working performance of the fuel cell and easily cause waste of raw materials. Therefore, it is necessary to perform thermal management on the fuel cell.

[0003] In the existing fuel cell thermal management technology, the use of immersion cooling technology for fuel cell thermal management is a commonly used technology, but the current immersion cooling technology mostly only considers the heat dissipation of the core working device stack in the fuel cell, while ignoring the overall heat dissipation of the fuel cell; in addition, in the existing fuel cell thermal management, the thermal management method is relatively rough, which can easily lead to uneven temperature of the fuel cell. Therefore, a new method is urgently needed to solve the defects in the existing technology. Summary of the invention

[0004] The present invention provides a thermal management method, circuit and device for a fuel cell system to solve the technical problem in the prior art that accurate thermal management of fuel cells cannot be performed.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a thermal management method for a fuel cell system, comprising:

[0006] Calculate the required coolant flow rate of the fuel cell based on the current temperature of the cooling box and the fuel cell stack;

[0007] Determine the required speed of each water pump in the cooling box according to the required coolant flow and the current coolant flow;

[0008] Each water pump is adjusted according to its required speed to adjust the heat dissipation power of the fuel cell stack, thereby making the temperature of the fuel cell meet the preset target temperature value.

[0009] It can be understood that, compared with the prior art, the present invention obtains the required coolant flow rate through the heat dissipation power of the fuel cell stack, and then obtains the coolant deviation in combination with the current coolant flow rate, thereby realizing the speed regulation of each water pump in the cooling box. The present invention detects the real-time cooling box temperature and solves the required speed of each water pump in the cooling box, so that multiple water pumps can be adjusted in time based on the actual temperature of the fuel cell. While ensuring that the overall temperature of the fuel cell meets the standard, the local temperature of the fuel cell is regulated, and the uniformity of the fuel cell is ensured; through the adjustment of multiple water pumps, the accuracy of temperature control is improved, and accurate thermal management of the fuel cell is realized.

[0010] As a preferred solution, the calculation of the required coolant flow rate of the fuel cell according to the current temperature of the cooling box and the fuel cell stack specifically includes:

[0011] Determine the heat dissipation power of the fuel cell stack according to the heat dissipation power of the coolant and the heat dissipation power of the gas in combination with the current temperature of the cooling box;

[0012] The required coolant flow rate of the fuel cell is calculated based on the heat dissipation power of the fuel cell stack and the current temperature of the fuel cell stack.

[0013] The accurate required coolant flow rate can be obtained by combining the temperature of the cooling box with the heat dissipation power of the fuel cell stack.

[0014] As a preferred solution, the heat dissipation power of the fuel cell stack is determined based on the heat dissipation power of the coolant and the heat dissipation power of the gas in combination with the current temperature of the cooling box, specifically including:

[0015] According to the coolant flow information, combined with the average temperature of each preset area in the cooling box, the heat dissipation power of the coolant is determined:

[0016] Q cool =C cool W cool [T st,out (t+t stack )-T st,in ],

[0017] Among them, Q cool is the heat dissipation power of the coolant, in kW; C cool W is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); cool is the coolant flow rate, in kg / s; t stack T is the coolant flow time, in seconds; st,in is the average temperature from the coolant inlet to the stack area, in K; T st,out is the average temperature from the stack to the coolant outlet, in K;

[0018] According to the heat of the gas leaving the stack and the heat of the gas entering the stack, the gas heat dissipation power is determined:

[0019] Q gas =Q gas,out -Q gas,in ,

[0020] Among them, Q gas is the gas heat dissipation power, Q gas,out is the heat of the gas leaving the stack, Q gas,in is the heat of the gas entering the stack;

[0021] According to the cooling power of the coolant and the cooling power of the gas, the cooling power of the fuel cell stack is determined:

[0022] Q dis =Q cool +Q gas ,

[0023] Among them, Q dis Provides heat dissipation for the fuel cell stack.

[0024] By dividing the cooling box into two areas according to the fuel cell stack and calculating the heat dissipation power of the entire cooling box, the heat generation of the fuel cell stack is fully considered, ensuring the accuracy of the heat dissipation power calculation.

[0025] As a preferred solution, the method of calculating the required coolant flow rate of the fuel cell based on the heat dissipation power of the fuel cell stack and the current temperature of the fuel cell stack specifically includes:

[0026] According to the heat dissipation power of the fuel cell stack and the temperature of the fuel cell stack, the required coolant flow rate of the fuel cell is calculated:

[0027]

[0028] Among them, W cool is the required coolant flow rate of the fuel cell; C stack is the specific heat capacity of the battery stack, in J / (kg·K); M stack is the mass of the battery stack, in kg; Q gen is the heat generation power of the battery stack, in kW; Q dis is the heat dissipation power of the battery stack, in kW; T stack is the stack temperature, in K; C cool is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); ΔT st It is the temperature difference from the coolant inlet to the fuel cell stack area and from the fuel cell stack to the coolant outlet area.

[0029] The accurate required coolant flow rate can be obtained through the temperature and heat dissipation power of the battery stack.

[0030] As a preferred solution, the method of determining the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate specifically includes:

[0031] According to the required coolant flow and the current coolant flow, combined with the preset control formula, the required speed of each water pump in the cooling box is determined:

[0032]

[0033] Where u(t) is the demand control quantity of the water pump; K p is the proportionality coefficient; T i is the integration time constant; T d is the differential time constant; E k and E k-1 is the coolant deviation calculated based on the required coolant flow and the current coolant flow; n pump is the required speed of the water pump; n 0,pump is the rated speed of the water pump; W 0,pump is the rated flow rate of the water pump; W u(t),cool Adjust the flow rate to the pump's needs.

[0034] By calculating the deviation of the coolant, the accuracy of the regulation of the water pump can be ensured, thereby ensuring accurate temperature regulation of the cooling box of the fuel cell.

[0035] Accordingly, an embodiment of the present invention provides a thermal management circuit of a fuel cell system, which is applicable to a thermal management method of a fuel cell system as described above, comprising: a collection module, a processor module and a drive module;

[0036] The signal output end of the acquisition module is electrically connected to the input end of the processor module;

[0037] The output end of the processor module is electrically connected to the control end of the drive module;

[0038] The acquisition module is used to collect the current cooling box temperature, stack temperature and coolant flow rate;

[0039] The processor module is used to obtain the required coolant flow rate of the fuel cell according to the temperature of the cooling box and the fuel cell stack, and then obtain the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate, so as to output the driving instruction of each water pump;

[0040] The driving module is used to complete the adjustment of each water pump according to the driving instruction.

[0041] It can be understood that, compared with the prior art, the present thermal management circuit obtains the required coolant flow rate through the heat dissipation power of the fuel cell stack, and then obtains the coolant deviation in combination with the current coolant flow rate, thereby realizing the speed regulation of each water pump in the cooling box. By detecting the real-time cooling box temperature, the required speed of each water pump in the cooling box is solved, so that multiple water pumps can be adjusted in time based on the actual temperature of the fuel cell, and the local temperature of the fuel cell is regulated while ensuring that the overall temperature of the fuel cell meets the standard, thereby ensuring the uniformity of the fuel cell; through the adjustment of multiple water pumps, the accuracy of temperature control is improved, and accurate thermal management of the fuel cell is realized.

[0042] Accordingly, an embodiment of the present invention provides a thermal management device for a fuel cell system, comprising: a first cooling box, a coolant conversion module, a fuel cell system, and a thermal management circuit for a fuel cell as described above;

[0043] The coolant inlet of the first cooling box is connected to the output end of the coolant conversion module, and the coolant outlet of the first cooling box is connected to the input end of the coolant conversion module to form a first cooling circuit;

[0044] The first cooling box includes: a plurality of water pumps and a plurality of guide plates;

[0045] The plurality of guide plates are alternately installed on the upper surface and the lower surface of the inner wall of the first cooling box in sequence to form a coolant guide path in the first cooling box;

[0046] The main components of the fuel cell system are installed in the coolant flow path so that the coolant can dissipate heat from the fuel cell stack;

[0047] The plurality of water pumps are installed between each adjacent guide plate;

[0048] The driving end of the driving module in the thermal management circuit is connected to the water pump control end so that the water pump can receive and execute the water pump driving instruction output by the driving module;

[0049] The acquisition module is used to collect the current first cooling box temperature, main device temperature and coolant flow rate;

[0050] The processor module is used to obtain the required coolant flow of the fuel cell according to the temperature of the first cooling box and the main component, and then obtain the required speed of each water pump in the first cooling box according to the required coolant flow and the current coolant flow, so as to output the driving instruction of each water pump.

[0051] It can be understood that the present invention improves the heat transfer area of ​​the fuel cell stack through single-phase immersion cooling technology, thereby improving the heat dissipation efficiency; through the temperature sensor, the accurate temperature of the cooling box and the fuel cell stack can be obtained, so as to better control the water pump to adjust the flow of the coolant, ensuring that the fuel cell stack is at a normal operating temperature; by setting a guide plate to form a coolant diversion path, the circulation efficiency of the coolant is improved, which is beneficial to the thermal management of the fuel cell stack.

[0052] As a preferred solution, the acquisition module includes: a number of temperature sensors;

[0053] The temperature sensors are installed on the inner wall of the first cooling box in sequence according to the same arrangement intervals.

[0054] The temperature sensors are evenly distributed, which can improve the collection efficiency and accuracy of the temperature sensors.

[0055] As a preferred solution, a plurality of guide holes are provided on the guide plate.

[0056] By adding guide holes on the guide plate, the coolant can not only flow in the coolant guide path guided by the guide plate, but also flow along the branch path formed by the guide holes, thereby increasing the heat exchange path between the coolant and the fuel cell stack and improving the heat exchange efficiency.

[0057] As a preferred solution, the thermal management device further comprises a second cooling box;

[0058] The input end of the second cooling box is connected to the output end of the cooling liquid conversion module, and the output end of the second cooling liquid is connected to the input end of the cooling liquid conversion module to form a second cooling circuit;

[0059] The second cooling box comprises: a water pump;

[0060] The water pumps are respectively installed at the coolant inlet and outlet of the second cooling box;

[0061] Auxiliary components of the fuel cell system are installed in the second cooling box.

[0062] By building a separate submerged water tank for the fuel cell system's air compressor and its controller, intercooler and DC / DC converter, the different operating temperatures of the fuel cell stack and accessories are fully taken into account, thereby improving the thermal management accuracy of the fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 : A schematic diagram of the steps of a thermal management method for a fuel cell system provided by an embodiment of the present invention;

[0064] Figure 2: A schematic diagram of a PID algorithm provided by an embodiment of the present invention;

[0065] Figure 3 : A connection diagram of a thermal management circuit of a fuel cell system provided by an embodiment of the present invention;

[0066] Figure 4 : A schematic diagram of the structure of a thermal management device for a fuel cell system provided by an embodiment of the present invention;

[0067] Figure 5 : A schematic diagram of the installation of a temperature sensor provided by an embodiment of the present invention;

[0068] Figure 6 : A design diagram of a guide plate with guide holes provided in an embodiment of the present invention;

[0069] Figure 7 : A schematic structural diagram of another thermal management device for a fuel cell system provided in an embodiment of the present invention;

[0070] Figure 8 : A flow chart of a temperature detection grid system provided by an embodiment of the present invention;

[0071] Fig. 9 : An internal schematic diagram of a cooling box provided by an embodiment of the present invention;

[0072] Among them, 201: acquisition module; 202: processor module; 203: drive module; 301: first cooling box; 302: coolant conversion module; 303: fuel cell system; 304: thermal management circuit of fuel cell; 401: connector; 402: threaded part; 403: shell; 404: thermistor; 501: guide plate with guide holes; 601: auxiliary water pump; 602: guide plate; 603: water pump; 604: discharge port. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] Embodiment 1

[0075] Please refer to Figure 1 , is a schematic diagram of the steps of a thermal management method for a fuel cell system provided in an embodiment of the present invention, including: steps S101-S103.

[0076] Step S101: Calculate the required coolant flow rate of the fuel cell based on the current temperature of the cooling box and the fuel cell stack.

[0077] In this embodiment, the calculation of the required coolant flow rate of the fuel cell according to the current temperature of the cooling box and the fuel cell stack specifically includes:

[0078] Determine the heat dissipation power of the fuel cell stack according to the heat dissipation power of the coolant and the heat dissipation power of the gas in combination with the current temperature of the cooling box;

[0079] The required coolant flow rate of the fuel cell is calculated based on the heat dissipation power of the fuel cell stack and the current temperature of the fuel cell stack.

[0080] The accurate required coolant flow rate can be obtained by combining the temperature of the cooling box with the heat dissipation power of the fuel cell stack.

[0081] In this embodiment, the heat dissipation power of the fuel cell stack is determined based on the heat dissipation power of the coolant and the heat dissipation power of the gas in combination with the current temperature of the cooling box, specifically including:

[0082] According to the coolant flow information, combined with the average temperature of each preset area in the cooling box, the heat dissipation power of the coolant is determined:

[0083] Q cool =C cool W cool [T st,out (t+t stack )-T st,in ],

[0084] Among them, Q cool is the heat dissipation power of the coolant, in kW; C cool W is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); cool is the coolant flow rate, in kg / s; t stack T is the coolant flow time, in seconds; st,in is the average temperature from the coolant inlet to the stack area, in K; T st,out is the average temperature from the stack to the coolant outlet, in K;

[0085] According to the heat of the gas leaving the stack and the heat of the gas entering the stack, the gas heat dissipation power is determined:

[0086] Q gas =Q gas,out -Q gas,in ,

[0087] Among them, Q gas is the gas heat dissipation power, Q gas,out is the heat of the gas leaving the stack, Qgas,in is the heat of the gas entering the stack;

[0088] According to the cooling power of the coolant and the cooling power of the gas, the cooling power of the fuel cell stack is determined:

[0089] Q dis =Q cool +Q gas ,

[0090] Among them, Q dis Provides heat dissipation for the fuel cell stack.

[0091] By dividing the cooling box into two areas according to the fuel cell stack and calculating the heat dissipation power of the entire cooling box, the heat generation of the fuel cell stack is fully considered, ensuring the accuracy of the heat dissipation power calculation.

[0092] In an optional embodiment, the gas heat dissipation power is determined according to the heat of the gas leaving the stack and the heat of the gas entering the stack, specifically including:

[0093] Q gas =Q gas,out -Q gas,in ,

[0094] Q gas,in =(W H2,in C H2 +W an,vapor,in C H2O,g )(T an,in -T0)+(W air,in C air +

[0095] W ca,vapor,in C H2O,g )(T ca,in -T0),

[0096] Q gas,out =(W H2,out C H2 +W an,vapor,out C H20,g )(T an,out -T0)+(W N2,out C N2 +

[0097] W o2,out C o2 +W ca,vapor,out c H2O,g +W ca,liquid,out C H2O.l )(T ca,out -T0),

[0098] Among them, Q gas,outThe heat of the gas leaving the reactor includes: unconsumed hydrogen, oxygen, water vapor and liquid water and nitrogen that does not participate in the reaction;

[0099] Q gas,in The heat of the gas entering the reactor includes air, hydrogen and water vapor;

[0100] C H2 , C air , C o2 , C H2O,g and C H2O.l are the specific heat capacities at constant pressure of hydrogen, air, oxygen, gaseous water and liquid water, respectively, in kJ / (K·kg);

[0101] T an,in , T ca,in , T an,out and T ca,out are the gas temperatures at the anode inlet, cathode inlet, anode outlet and cathode outlet of the stack, respectively, in K;

[0102] T0 is the external ambient temperature, in K;

[0103] W H2,in , W an,vapor,in , W air,in and W ca,vapor,in They are the hydrogen flow rate into the stack, the anode water vapor flow rate into the stack, the air flow rate into the stack and the cathode water vapor flow rate into the stack, in kg / s;

[0104] W H2,out , W an,vapor,out , W N2,out , W o2,out , W ca,vapor,out and W ca,liquid,out They are respectively the hydrogen flow rate out of the stack, the anode water vapor flow rate out of the stack, the nitrogen flow rate out of the stack, the oxygen flow rate out of the stack, the cathode water vapor flow rate out of the stack and the cathode liquid water flow rate out of the stack, and the unit is kg / s.

[0105] It should be noted that when the fuel cell is working, about 95% of the heat is taken away by the coolant, the gas heat dissipation capacity is 3% to 5%, and the heat radiation accounts for only about 1%. Therefore, when calculating the heat dissipation power of the fuel cell stack, this embodiment only considers the coolant heat dissipation and gas heat dissipation.

[0106] It should be noted that, based on the working characteristics of the fuel cell stack and the coolant, the embodiment of the present invention uses the area between the fuel cell stack and the two guide plates as a partition to divide the area in the cooling box into two parts, the first part is the area from the coolant inlet to the fuel cell stack, and the second part is the area from the fuel cell stack to the coolant outlet.

[0107] In this embodiment, the calculation of the required coolant flow rate of the fuel cell based on the heat dissipation power of the fuel cell stack and the current temperature of the fuel cell stack specifically includes:

[0108] According to the heat dissipation power of the fuel cell stack and the temperature of the fuel cell stack, the required coolant flow rate of the fuel cell is calculated:

[0109]

[0110] Among them, W cool is the required coolant flow rate of the fuel cell; C stack is the specific heat capacity of the battery stack, in J / (kg·K); M stack is the mass of the battery stack, in kg; Q gen is the heat generation power of the battery stack, in kW; Q dis is the heat dissipation power of the battery stack, in kW; T stack is the stack temperature, in K; C cool is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); ΔT st It is the temperature difference from the coolant inlet to the fuel cell stack area and from the fuel cell stack to the coolant outlet area.

[0111] The accurate required coolant flow rate can be obtained through the temperature and heat dissipation power of the battery stack.

[0112] Step S102: Determine the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate.

[0113] In this embodiment, determining the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate specifically includes:

[0114] According to the required coolant flow and the current coolant flow, combined with the preset control formula, the required speed of each water pump in the cooling box is determined:

[0115]

[0116] Where u(t) is the demand control quantity of the water pump; K p is the proportionality coefficient; T i is the integration time constant; T d is the differential time constant; E k and E k-1 is the coolant deviation calculated based on the required coolant flow and the current coolant flow; n pump is the required speed of the water pump; n 0,pump is the rated speed of the water pump; W 0,pump is the rated flow rate of the water pump; W u(t),coolAdjust the flow rate to the pump's needs.

[0117] By calculating the deviation of the coolant, the accuracy of the regulation of the water pump can be ensured, thereby ensuring accurate temperature regulation of the cooling box of the fuel cell.

[0118] In an alternative embodiment, please refer to Figure 2 , is a schematic diagram of a PID algorithm provided by an embodiment of the present invention, wherein the difference between the calculated required coolant flow rate and the actual flow rate is used as the input parameter of the PID controller, the PID controller, the PID algorithm is divided into three parts: proportional part, integral part, and differential part. The proportional part is used to shorten the time to reach the target temperature, the integral part is used to eliminate the steady-state error, and the differential part is used to reduce the dynamic deviation;

[0119] The preset control formula is the control formula of the PID controller:

[0120]

[0121] Among them, u(t) is the control quantity output by the controller, e(t) is the deviation signal, that is, the difference between the given quantity and the output quantity; k p is the proportionality coefficient; T i is the integration time constant; T d is the differential time constant.

[0122] Step S103: Each water pump is adjusted according to the required speed of each water pump to adjust the heat dissipation power of the fuel cell stack, so as to make the temperature of the fuel cell meet the preset target temperature value.

[0123] This embodiment obtains the required coolant flow rate through the heat dissipation power of the fuel cell stack, and then obtains the coolant deviation in combination with the current coolant flow rate, thereby realizing the speed adjustment of each water pump in the cooling box. This embodiment detects the real-time cooling box temperature and solves the required speed of each water pump in the cooling box, so that multiple water pumps can be adjusted in time based on the actual temperature of the fuel cell, and the local temperature of the fuel cell is regulated while ensuring that the overall temperature of the fuel cell meets the standard, thereby ensuring the uniformity of the fuel cell; through the adjustment of multiple water pumps, the accuracy of temperature control is improved, and accurate thermal management of the fuel cell is realized.

[0124] Embodiment 2

[0125] Please refer to Figure 3 , is a connection diagram of a thermal management circuit of a fuel cell system provided by an embodiment of the present invention, which is applicable to a thermal management method of a fuel cell system as described in Embodiment 1, including: a collection module 201, a processor module 202 and a drive module 203;

[0126] Wherein, the signal output end of the acquisition module 201 is electrically connected to the input end of the processor module 202;

[0127] The output end of the processor module 202 is electrically connected to the control end of the driving module 203;

[0128] The acquisition module 201 is used to collect the current cooling box temperature, stack temperature and coolant flow rate;

[0129] The processor module 202 is used to obtain the required coolant flow rate of the fuel cell according to the temperature of the cooling box and the fuel cell stack, and then obtain the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate, so as to output a driving instruction for each water pump;

[0130] The driving module 203 is used to complete the adjustment of each water pump according to the driving instruction.

[0131] The thermal management circuit of this embodiment obtains the required coolant flow rate through the heat dissipation power of the fuel cell stack, and then obtains the coolant deviation in combination with the current coolant flow rate, thereby realizing the speed adjustment of each water pump in the cooling box. By detecting the real-time cooling box temperature, the required speed of each water pump in the cooling box is solved, so that multiple water pumps can be adjusted in time based on the actual temperature of the fuel cell, and the local temperature of the fuel cell is regulated while ensuring that the overall temperature of the fuel cell meets the standard, thereby ensuring the uniformity of the fuel cell; through the adjustment of multiple water pumps, the accuracy of temperature control is improved, and accurate thermal management of the fuel cell is realized.

[0132] Embodiment 3

[0133] Please refer to Figure 4 , is a schematic structural diagram of a thermal management device for a fuel cell system provided in an embodiment of the present invention, comprising: a first cooling box 301, a coolant conversion module 302, a fuel cell system 303 and a thermal management circuit 304 of a fuel cell as described in the second embodiment;

[0134] The coolant inlet of the first cooling box 301 is connected to the output end of the coolant conversion module 302, and the coolant outlet of the first cooling box 301 is connected to the input end of the coolant conversion module 302 to form a first cooling circuit;

[0135] The first cooling box 301 includes: a plurality of water pumps, a plurality of guide plates;

[0136] The guide plates are alternately installed on the upper surface and the lower surface of the inner wall of the first cooling box 301 in sequence to form a coolant guide path in the first cooling box 301;

[0137] The main components of the fuel cell system 303 are installed in the coolant flow path so that the coolant can dissipate heat from the fuel cell stack;

[0138] The plurality of water pumps are installed between each adjacent guide plate;

[0139] The driving end of the driving module in the thermal management circuit 304 is connected to the water pump control end so that the water pump can receive and execute the water pump driving instruction output by the driving module;

[0140] The acquisition module is used to collect the current temperature of the first cooling box 301, the temperature of the main device and the coolant flow;

[0141] The processor module is used to obtain the required coolant flow of the fuel cell according to the temperature of the first cooling box and the main component, and then obtain the required speed of each water pump in the first cooling box 301 according to the required coolant flow and the current coolant flow, so as to output the driving instruction of each water pump.

[0142] It should be noted that the main components of the fuel cell system described in this embodiment include: a fuel cell stack and a hydrogen pump, and the auxiliary components include: an air compressor and its controller, a DC / DC converter and an intercooler.

[0143] In this embodiment, the acquisition module includes: a number of temperature sensors;

[0144] The temperature sensors are installed on the inner wall of the first cooling box in sequence according to the same arrangement intervals.

[0145] The temperature sensors are evenly distributed, which can improve the collection efficiency and accuracy of the temperature sensors.

[0146] In this embodiment, a plurality of guide holes are arranged on the guide plate.

[0147] By adding guide holes on the guide plate, the coolant can not only flow in the coolant guide path guided by the guide plate, but also flow along the branch path formed by the guide holes, thereby increasing the heat exchange path between the coolant and the fuel cell stack and improving the heat exchange efficiency.

[0148] In this embodiment, a discharge hole is provided at the bottom of the first cooling box.

[0149] By adding a drainage and exhaust interface to the fuel cell stack, it is possible to prevent the water and gas generated by the fuel cell stack from being directly discharged into the first cooling box, thereby affecting the operation of the coolant and reducing the heat transfer effect.

[0150] In an alternative embodiment, please refer to Figure 5 , is a schematic diagram of installing a temperature sensor provided by an embodiment of the present invention;

[0151] The temperature sensor adopts an analog temperature sensor, such as an NTC thermistor, so as to realize miniaturization while having the characteristics of small fluctuation of resistance value and temperature characteristics, fast response to various temperature changes, and high sensitivity and high precision detection;

[0152] The temperature sensor comprises: a connector 401, a threaded portion 402, a housing 403 and a thermistor 404;

[0153] The temperature sensor is fixed to the first cooling box housing 405 via a threaded portion 402, the connector 401 of the temperature sensor is placed outside the cooling box, and the thermistor 404 is placed inside the cooling box;

[0154] The housing 403 is used to fix the thermistor 404, and the connector 401 is used to output temperature data;

[0155] After the temperature sensor is installed, use adhesive material to waterproof the installation holes to prevent leakage.

[0156] In an alternative embodiment, please refer to Figure 6 , is a design diagram of a guide plate with guide holes provided in an embodiment of the present invention; wherein the guide plate with guide holes 501 includes a plurality of guide holes;

[0157] Adding guide holes on the guide plate allows the coolant to flow not only in the main path guided by the guide plate, but also along the branch path formed by the guide holes; using a porous guide plate in the cooling box increases the heat exchange path between the coolant and the fuel cell stack, indirectly increasing the flow coverage area and improving the heat exchange efficiency.

[0158] In an optional embodiment, the water pump between the guide plates can use a threaded paddle agitator, which has the characteristics of simple structure, easy installation and high speed, can be applied to low viscosity liquids and reduce production costs; the agitator is installed vertically to the ground from top to bottom from the top of the cooling box, and the power supply part of the agitator is placed outside the cooling box.

[0159] In an optional embodiment, a coolant suitable for use in this embodiment can be selected based on the characteristics of the coolant, and the selection criteria include: insulation, boiling point, specific heat capacity, thermal conductivity, flame retardancy, corrosion resistance, anti-fouling, service life, corrosiveness, foam tendency, density and viscosity.

[0160] In an optional embodiment, the applicable coolant of this embodiment has an optimal operating temperature range of 70-82° C., and a boiling point higher than 82° C.; for example, the Novec series 7300 electronic fluorinated liquid developed by 3M Company.

[0161] In this embodiment, the thermal management device further comprises a second cooling box;

[0162] The input end of the second cooling box is connected to the output end of the cooling liquid conversion module, and the output end of the second cooling liquid is connected to the input end of the cooling liquid conversion module to form a second cooling circuit;

[0163] The second cooling box comprises: a water pump;

[0164] The water pumps are respectively installed at the coolant inlet and outlet of the second cooling box;

[0165] Auxiliary components of the fuel cell system are installed in the second cooling box.

[0166] By building a separate submerged water tank for the fuel cell system's air compressor and its controller, intercooler and DC / DC converter, the different operating temperatures of the fuel cell stack and accessories are fully taken into account, thereby improving the thermal management accuracy of the fuel cell system.

[0167] This embodiment uses single-phase immersion cooling technology to increase the heat transfer area of ​​the fuel cell stack, thereby improving the heat dissipation efficiency; the temperature sensor can obtain accurate cooling box and fuel cell stack temperatures, thereby better controlling the water pump to adjust the flow of coolant, ensuring that the fuel cell stack is at a normal operating temperature; the guide plate is provided to form a coolant guide path, thereby improving the circulation efficiency of the coolant, which is beneficial to the thermal management of the fuel cell stack.

[0168] Embodiment 4

[0169] Please refer to Figure 7 , which is a structural schematic diagram of another thermal management device of a fuel cell system provided by an embodiment of the present invention; comprising: a main cooling box, a secondary cooling box, an auxiliary water pump, a water pump, a compressor, an off-vehicle condenser, a first expansion valve, a second expansion valve, a third expansion valve, a flow divider, a PTC, an off-vehicle evaporator, and an on-vehicle evaporator;

[0170] The fuel cell stack and hydrogen pump are placed in the main cooling box, and the air compressor and its controller, intercooler and DC / DC converter are placed in the auxiliary cooling box.

[0171] The main cooling box, PTC, second expansion valve, flow divider, off-vehicle condenser, compressor and off-vehicle evaporator are connected in sequence;

[0172] The auxiliary cooling box, the third expansion valve, the flow divider, the off-vehicle condenser, the compressor and the off-vehicle evaporator are connected in sequence;

[0173] The in-vehicle evaporator, the compressor, the out-vehicle condenser, the diverter and the first expansion valve are connected in sequence.

[0174] In an optional embodiment, when the ambient temperature is above zero degrees Celsius, the compressor compresses the low-temperature and low-pressure gaseous coolant output by the off-vehicle evaporator and the off-vehicle evaporator into a high-temperature and high-pressure gaseous coolant, and inputs it to the off-vehicle condenser; dissipates heat to the atmosphere through the off-vehicle condenser to form a medium-temperature and high-pressure liquid coolant; and transmits it to the corresponding expansion valve according to a preset demand through the diverter;

[0175] The first expansion valve converts the medium-temperature high-pressure liquid into a low-temperature low-pressure liquid coolant at 0°C, the second expansion valve converts the medium-temperature high-pressure liquid into a low-temperature low-pressure liquid coolant at 30°C, and the third expansion valve converts the medium-temperature high-pressure liquid into a low-temperature low-pressure liquid coolant at 35°C;

[0176] The coolant output by the first expansion valve is supplied to the air conditioner in the vehicle through the in-vehicle evaporator. After absorbing the heat in the vehicle, the coolant is changed from liquid to gas through the in-vehicle evaporator and transmitted to the compressor.

[0177] The coolant outputted by the second expansion valve flows into the main cooling box for heat exchange, and then flows back to the external evaporator, so that the external evaporator changes the coolant from liquid to gas and transmits it to the compressor;

[0178] The coolant output by the third expansion valve flows into the auxiliary cooling box for heat exchange, and then flows back to the external evaporator, so that the external evaporator changes the coolant from liquid to gas and transmits it to the compressor.

[0179] In an optional embodiment, when the ambient temperature is below zero degrees Celsius, the first expansion valve is closed and no heat exchange is performed in the vehicle; the PTC is turned on to heat the coolant flowing through the main cooling box until the battery stack is at a normal operating temperature;

[0180] When the battery stack is at normal operating temperature, the diverter distributes coolant to the first expansion valve to start heat exchange in the vehicle.

[0181] In an alternative embodiment, please refer to Figure 8 , which is a flow chart of a temperature detection grid system provided by an embodiment of the present invention; wherein the temperature detection grid system pre-sets a target temperature value, a control period, a sampling period and a PID parameter, periodically detects the temperature of each temperature sensor in the cooling box, and obtains the average temperature from the coolant inlet to the battery stack area and from the battery stack to the coolant outlet area;

[0182] Determining whether the average temperature reaches a preset expected value;

[0183] If the preset expected value is reached, the temperature sensor is detected. When all temperature sensors are within the preset operating temperature range, the current round of temperature control ends;

[0184] If the preset expected value is not reached, the expected flow rate of the coolant is calculated, and according to the deviation between the expected flow rate and the actual flow rate, the PID controller is used to adjust the water pump speed and control the coolant flow rate until the preset expected temperature is reached, thus ending this round of temperature control.

[0185] In an alternative embodiment, please refer to Fig. 9 , is a schematic diagram of the interior of a cooling box provided by an embodiment of the present invention; wherein the cooling box comprises: an auxiliary water pump 601, a guide plate 602, a water pump 603 and a discharge port 604;

[0186] The auxiliary water pump 601 is installed at the coolant outlet and outlet of the cooling box;

[0187] The guide plates 602 are alternately installed on the upper and lower parts of the inner wall of the cooling box;

[0188] The water pump 603 is sequentially installed between the two guide plates;

[0189] A discharge port 604 for draining water and exhausting gas from the power stack is reserved at the bottom of the cooling box to prevent water and gas generated by the power stack from being directly discharged into the cooling box and affecting the properties of the coolant;

[0190] The inlet and outlet of the cooling box use a low-pressure submersible pump as a means of exchanging the coolant with the cooling box;

[0191] A number of guide plates and a number of water pumps are installed in the cooling box.

[0192] In summary, the embodiment of the present invention solves the required coolant flow rate, and then combines the current coolant flow rate to obtain the coolant deviation, thereby realizing the speed adjustment of each water pump in the cooling box. The embodiment of the present invention detects the real-time cooling box temperature to solve the required speed of each water pump in the cooling box, so that multiple water pumps can be adjusted in time based on the actual temperature of the fuel cell, and the local temperature of the fuel cell is regulated while ensuring that the overall temperature of the fuel cell meets the standard, thereby ensuring the uniformity of the fuel cell; through the adjustment of multiple water pumps, the accuracy of temperature control is improved, and accurate thermal management of the fuel cell is realized.

[0193] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A thermal management method for a fuel cell system, characterized in that: include: The required coolant flow rate of the fuel cell is calculated according to the current temperature of the cooling box and the stack, wherein the calculation of the required coolant flow rate of the fuel cell according to the current temperature of the cooling box and the stack specifically includes: determining the stack heat dissipation power of the fuel cell according to the coolant heat dissipation power and the gas heat dissipation power in combination with the current temperature of the cooling box; calculating the required coolant flow rate of the fuel cell according to the stack heat dissipation power of the fuel cell in combination with the current temperature of the stack; wherein the determination of the stack heat dissipation power of the fuel cell according to the coolant heat dissipation power and the gas heat dissipation power in combination with the current temperature of the cooling box specifically includes: The current temperature of the cooling box includes: the average temperature from the coolant inlet to the stack area and the average temperature from the stack to the coolant outlet area; According to the coolant flow information, combined with the average temperature from the coolant inlet to the stack area and the average temperature from the stack to the coolant outlet area, the heat dissipation power of the coolant is determined: Q cool =C cool W cool [T st,out (t+t stack )-T st,in ], Among them, Q cool is the heat dissipation power of the coolant, in kW; C cool W is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); cool is the coolant flow rate, in kg / s; t stack T is the coolant flow time, in seconds; st,in is the average temperature from the coolant inlet to the stack area, in K; T st,out is the average temperature from the stack to the coolant outlet area, in K; According to the gas power out of the stack and the gas power in the stack, the gas heat dissipation power is determined: Q gas =Q gas,out -Q gas,in , Among them, Q gas is the gas heat dissipation power, Q gas,out is the gas power out of the stack, Q gas,in is the gas power entering the stack; According to the cooling power of the coolant and the cooling power of the gas, the cooling power of the fuel cell stack is determined: Q dis =Q cool +Q gas , Among them, Q dis Provide heat dissipation for the fuel cell stack; Determine the required speed of each water pump in the cooling box according to the required coolant flow and the current coolant flow; Each water pump is adjusted according to its required speed to adjust the heat dissipation power of the fuel cell stack, thereby making the temperature of the fuel cell meet the preset target temperature value.

2. A thermal management method for a fuel cell system according to claim 1, characterized in that: The method of calculating the required coolant flow rate of the fuel cell according to the heat dissipation power of the fuel cell stack and the current temperature of the fuel cell stack specifically includes: According to the heat dissipation power of the fuel cell stack and the temperature of the fuel cell stack, the required coolant flow rate of the fuel cell is calculated: Among them, W cool is the required coolant flow rate of the fuel cell; C stack is the specific heat capacity of the battery stack, in J / (kg·K); M stack is the mass of the battery stack, in kg; Q gen is the heat generation power of the battery stack, in kW; Q dis is the heat dissipation power of the battery stack, in kW; T stack is the stack temperature, in K; C cool is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); ΔT st It is the temperature difference from the coolant inlet to the fuel cell stack area and from the fuel cell stack to the coolant outlet area.

3. A thermal management method for a fuel cell system according to claim 1, characterized in that: Determining the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate specifically includes: According to the required coolant flow and the current coolant flow, combined with the preset control formula, the required speed of each water pump in the cooling box is determined: Where u(t) is the demand control quantity of the water pump; K p is the proportionality coefficient; T i is the integration time constant; T d is the differential time constant; E k and E k-1 is the coolant deviation calculated based on the required coolant flow and the current coolant flow; n pump is the required speed of the water pump; n 0,pump is the rated speed of the water pump; W 0,pump is the rated flow rate of the water pump; W u(t),cool Adjust the flow rate to the pump's needs.

4. A thermal management circuit for a fuel cell system, applicable to a thermal management method for a fuel cell system as claimed in any one of claims 1 to 3, characterized in that: include: Acquisition module, processor module and driver module; The signal output end of the acquisition module is electrically connected to the input end of the processor module; The output end of the processor module is electrically connected to the control end of the drive module; The acquisition module is used to collect the current cooling box temperature, stack temperature and coolant flow rate; The processor module is used to obtain the required coolant flow rate of the fuel cell according to the temperature of the cooling box and the stack, and then obtain the required speed of each water pump in the cooling box according to the required coolant flow rate and the current coolant flow rate, so as to output the driving instruction of each water pump; wherein, the calculation of the required coolant flow rate of the fuel cell according to the current temperature of the cooling box and the stack specifically includes: determining the stack heat dissipation power of the fuel cell according to the coolant heat dissipation power and the gas heat dissipation power in combination with the current temperature of the cooling box; calculating the required coolant flow rate of the fuel cell according to the stack heat dissipation power of the fuel cell in combination with the current temperature of the stack; wherein, the determination of the stack heat dissipation power of the fuel cell according to the coolant heat dissipation power and the gas heat dissipation power in combination with the current temperature of the cooling box specifically includes: The current temperature of the cooling box includes: the average temperature from the coolant inlet to the stack area and the average temperature from the stack to the coolant outlet area; According to the coolant flow information, combined with the average temperature from the coolant inlet to the stack area and the average temperature from the stack to the coolant outlet area, the heat dissipation power of the coolant is determined: Q cool =C cool W cool [T st,out (t+t stack )-T st,in ], Among them, Q cool is the heat dissipation power of the coolant, in kW; C cool W is the constant pressure specific heat capacity of the coolant, in kJ / (K·kg); cool is the coolant flow rate, in kg / s; t stack T is the coolant flow time, in seconds; st,in is the average temperature from the coolant inlet to the stack area, in K; T st,out is the average temperature from the stack to the coolant outlet, in K; According to the gas power out of the stack and the gas power in the stack, the gas heat dissipation power is determined: Q gas =Q gas,out -Q gas,in , Among them, Q gas is the gas heat dissipation power, Q gas,out is the gas power out of the stack, Q gas,in is the gas power entering the stack; According to the cooling power of the coolant and the cooling power of the gas, the cooling power of the fuel cell stack is determined: Q dis =Q cool +Q gas , Among them, Q dis Provide heat dissipation for the fuel cell stack; The driving module is used to complete the adjustment of each water pump according to the driving instruction.

5. A thermal management device for a fuel cell system, characterized in that: include: A first cooling box, a coolant conversion module, a fuel cell system and a thermal management circuit of a fuel cell as claimed in claim 4; The coolant inlet of the first cooling box is connected to the output end of the coolant conversion module, and the coolant outlet of the first cooling box is connected to the input end of the coolant conversion module to form a first cooling circuit; The first cooling box includes: a plurality of water pumps and a plurality of guide plates; The guide plates are alternately installed on the upper surface and the lower surface of the inner wall of the first cooling box in sequence to form a coolant guide path in the first cooling box; The main components of the fuel cell system are installed in the coolant flow path so that the coolant can dissipate heat from the fuel cell stack; The plurality of water pumps are installed between each adjacent guide plate; The driving end of the driving module in the thermal management circuit is connected to the water pump control end so that the water pump can receive and execute the water pump driving instruction output by the driving module; The acquisition module is used to collect the current first cooling box temperature, main device temperature and coolant flow rate; The processor module is used to obtain the required coolant flow of the fuel cell according to the temperature of the first cooling box and the main component, and then obtain the required speed of each water pump in the first cooling box according to the required coolant flow and the current coolant flow, so as to output the driving instruction of each water pump.

6. A thermal management device for a fuel cell system as claimed in claim 5, characterized in that: The acquisition module includes: a number of temperature sensors; The temperature sensors are installed on the inner wall of the first cooling box in sequence according to the same arrangement intervals.

7. A thermal management device for a fuel cell system according to claim 5, characterized in that: A plurality of guide holes are arranged on the guide plate.

8. A thermal management device for a fuel cell system as claimed in claim 5, characterized in that: The thermal management device also includes a second cooling box; The input end of the second cooling box is connected to the output end of the cooling liquid conversion module, and the output end of the second cooling liquid is connected to the input end of the cooling liquid conversion module to form a second cooling circuit; The second cooling box includes: a water pump; The water pumps are respectively installed at the coolant inlet and outlet of the second cooling box; Auxiliary components of the fuel cell system are installed in the second cooling box.

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