Fuel cell stack cooling control method and cooling control device

Abstract

To provide a technology that can ensure cooling accuracy while reducing the control load when cooling a plurality of fuel cell stacks connected in parallel to a common radiator through a refrigerant passage.SOLUTION: A cooling control method includes the steps of: (a) calculating an actual pump flow rate for each pump; (b) calculating a radiator flow rate using the sum of the actual pump flow rates for each pump; (c) calculating a common pressure loss which is the pressure loss for a common flow path in the refrigerant passage that is common to a plurality of fuel cell stacks, using the radiator flow rate; (d) calculating individual pressure losses which are the pressure losses for each individual flow path in the refrigerant passage corresponding to each of the plurality of fuel cell stacks; and (e) operating each pump using a total pressure loss which is the sum of the common pressure loss and the individual pressure loss, and the required pump flow rate for each pump.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a cooling control method and a cooling control device for a fuel cell stack. [Background technology]

[0002] A technique for controlling the rotation speed of each pump in a power system in which multiple fuel cell systems, each having a fuel cell stack and a pump for supplying coolant to the fuel cell stack, are connected in parallel to a single radiator via cooling passages, is known (Patent Document 1).This technique controls the rotation speed of the pumps by at least one of cooperative control, which unifies the rotation speed of the pumps in the multiple fuel cell systems, and independent control, which sets and operates the rotation speed of the pump in each fuel cell system individually. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-154531 Summary of the Invention [Problem to be solved by the invention]

[0004] In cooperative control, the rotation speed of each pump is set uniformly. This reduces the control load when setting the pump rotation speed compared to individual control, but there is a possibility that the refrigerant cannot be supplied to each fuel cell stack at a flow rate appropriate for that fuel cell stack. In individual control, the rotation speed of each pump is set individually. This increases the possibility of supplying the refrigerant to each fuel cell stack at a flow rate appropriate for that fuel cell stack compared to cooperative control, but there is a risk that the control load when setting the pump rotation speed will increase. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one aspect of the present disclosure, there is provided a cooling control method for a fuel cell stack, the cooling control method for a plurality of fuel cell stacks connected in parallel to a common radiator by coolant passages through which a coolant flows, the coolant passages being provided with pumps for circulating the coolant between the fuel cell stacks and the radiator, the cooling control method including the steps of: (a) calculating an actual pump flow rate for each of the pumps; (b) calculating a radiator flow rate using a sum of the actual pump flow rates for each of the pumps; (c) calculating a common pressure loss, which is the pressure loss in a common flow path of the coolant passages common to the plurality of fuel cell stacks, using the radiator flow rate; (d) calculating an individual pressure loss, which is the pressure loss in each individual flow path of the coolant passages corresponding to each of the plurality of fuel cell stacks; and (e) operating each of the pumps using a total pressure loss, which is the sum of the common pressure loss and the individual pressure loss, and a required pump flow rate for each of the pumps. According to this aspect, the rotation speed of each pump can be set individually using the pressure loss when the coolant passes through the coolant passage and the required pump flow rate for each pump. This increases the likelihood that a coolant flow rate appropriate for each fuel cell stack can be supplied to each fuel cell stack compared to when the rotation speed of each pump is set uniformly. In this case, the radiator flow rate can be calculated using the sum of the actual pump flow rates for each pump, and the radiator flow rate can be used to calculate the common pressure loss. In other words, the common flow path can be considered as a single system common to multiple fuel cell stacks to calculate the common pressure loss. This reduces the control load when setting the pump rotation speed while ensuring cooling accuracy. (2) In the above aspect, in the step (a), the actual pump flow rate may be calculated using the rotation speed of the pump at a specific time point prior to the calculation of the actual pump flow rate and the total pressure loss at the specific time point. According to this aspect, the actual pump flow rate can be calculated using the rotation speed of the pump at a specific time point prior to the calculation of the actual pump flow rate and the total pressure loss at the specific time point. (3) In the above aspect, in the step (e), the rotation speed of the pump may be calculated by applying the total pressure loss and the required pump flow rate to a prepared characteristic map, and the characteristic map may represent a correlation between the pump flow rate, the total pressure loss, and the rotation speed of the pump. According to this aspect, the rotation speed of the pump can be calculated by applying the total pressure loss and the required pump flow rate to the prepared characteristic map. (4) In the above aspect, in the step (c), the common pressure loss may be calculated by multiplying the radiator flow rate by a predetermined pressure loss coefficient, and in the step (d), the individual pressure losses may be calculated by multiplying the actual pump flow rate of the corresponding pump by a predetermined pressure loss coefficient. According to this aspect, the common pressure loss can be calculated by multiplying the radiator flow rate by the predetermined pressure loss coefficient. Also, the individual pressure losses can be calculated by multiplying the actual pump flow rate of the corresponding pump by the predetermined pressure loss coefficient. (5) According to another aspect of the present disclosure, there is provided a cooling control device for a fuel cell stack, the cooling control device for a plurality of fuel cell stacks connected in parallel to a common radiator by coolant passages through which a coolant flows, the coolant passages being provided with pumps for circulating the coolant between the fuel cell stack and the radiator, the cooling control device including: an actual flow rate calculation unit that calculates an actual pump flow rate for each pump; a radiator flow rate calculation unit that calculates a radiator flow rate using a sum of the actual pump flow rates for each pump; a common pressure loss calculation unit that calculates a common pressure loss, which is the pressure loss in a common flow path of the coolant passage common to the plurality of fuel cell stacks, using the radiator flow rate; an individual pressure loss calculation unit that calculates an individual pressure loss, which is the pressure loss in each individual flow path of the coolant passage for each of the plurality of fuel cell stacks; and an operation control unit that operates each of the pumps using a total pressure loss, which is the sum of the common pressure loss and the individual pressure loss, and a required pump flow rate for each pump. According to this aspect, the cooling control device can individually set and operate each pump's rotation speed using the pressure loss when the refrigerant passes through the refrigerant passage and the required pump flow rate for each pump. This increases the likelihood that a refrigerant flow rate appropriate for each fuel cell stack can be supplied to each pump, compared to when each pump's rotation speed is set uniformly. In this case, the cooling control device can calculate the radiator flow rate using the sum of the actual pump flow rates for each pump, and then calculate the common pressure loss using the radiator flow rate. In other words, the cooling control device can calculate the common pressure loss by treating the common flow path as a single system common to multiple fuel cell stacks. This reduces the control load when setting the pump rotation speed, while ensuring cooling accuracy. The present disclosure can be realized in various forms other than the above-described fuel cell stack cooling control method and cooling control device, such as a cooling system including a cooling device and a cooling control device, a method for manufacturing a cooling control device and a cooling system, a control method for a cooling control device and a cooling system, a computer program for implementing the control method, a non-transitory recording medium on which the computer program is recorded, etc. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the configuration of a cooling system. [Figure 2] FIG. 2 is a block diagram showing the configuration of a cooling control device. [Figure 3] A conceptual diagram of a characteristic map. [Figure 4] 4 is a flowchart showing a fuel cell stack cooling control method. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. Implementation: FIG. 1 is a diagram showing the configuration of a cooling system 1. The cooling system 1 is a system for cooling fuel cell stacks 11 and 12. The fuel cell stacks 11 and 12 have a stack structure in which a plurality of unit cells are stacked. Each unit cell includes an electrolyte membrane, a membrane electrode assembly (MEA) formed by joining an anode formed on one side of the electrolyte membrane and a cathode formed on the other side of the electrolyte membrane, and a pair of separators that sandwich the membrane electrode assembly from both sides. The fuel cell stacks 11 and 12 generate electricity through an electrochemical reaction by supplying hydrogen to the anode and air to the cathode. The cooling system 1 includes a cooling device 20 and a cooling control device 50.

[0009] The cooling device 20 circulates and supplies a coolant to the fuel cell stacks 11, 12 to cool the fuel cell stacks 11, 12. The cooling device 20 includes a radiator 210, two pumps 211, 212, two temperature sensors 231, 232, a coolant passage 250, and two rotary valves 291, 292.

[0010] The radiator 210 cools, through heat exchange, the refrigerant discharged from the fuel cell stacks 11 and 12. In this embodiment, the first fuel cell stack 11 and the second fuel cell stack 12 are connected in parallel to a single shared radiator 210 via a refrigerant passage 250.

[0011] Pumps 211 and 212 are provided for each of the fuel cell stacks 11 and 12. The first pump 211 circulates the coolant between the first fuel cell stack 11 and the radiator 210. The second pump 212 circulates the coolant between the second fuel cell stack 12 and the radiator 210.

[0012] Temperature sensors 231, 232 are provided for each fuel cell stack 11, 12. The first temperature sensor 231 measures the temperature of the coolant discharged from the first fuel cell stack 11 and outputs the result to the cooling control device 50. The second temperature sensor 232 measures the temperature of the coolant discharged from the second fuel cell stack 12 and outputs the result to the cooling control device 50.

[0013] A coolant flows through the coolant passage 250. The direction of the coolant flow is indicated by arrows in Fig. 1. The coolant passage 250 has common flow paths 261 and 262 and individual flow paths 271a to 271f and 272a to 272f.

[0014] The common flow paths 261, 262 are flow paths of the refrigerant passage 250 that are common to the two fuel cell stacks 11, 12. In Fig. 1, the common flow paths 261, 262 are indicated by dashed lines. The first common flow path 261 is a flow path that supplies refrigerant from a main junction point CT, which is a junction point of the refrigerants discharged from the fuel cell stacks 11, 12, to the radiator 210. The second common flow path 262 is a flow path that supplies refrigerant from the radiator 210 to a branch point BR where the radiator 210 branches into first individual flow paths 271a-271f and second individual flow paths 272a-272f.

[0015] The individual flow paths 271a to 271f and 272a to 272f are flow paths corresponding to the two fuel cell stacks 11 and 12, respectively. The first individual flow paths 271a to 271f are individual flow paths corresponding to the first fuel cell stack 11. In FIG. 1, the first individual flow paths 271a to 271f are indicated by dashed dotted lines. The second individual flow paths 272a to 272f are individual flow paths corresponding to the second fuel cell stack 12. In FIG. 1, the second individual flow paths 272a to 272f are indicated by dashed two-dotted lines. Each of the individual flow paths 271a to 271f and 272a to 272f has five main flow paths 271a to 271e and 272a to 272e, and a sub-flow path 271f and 272f. The first main flow paths 271a, 272a are flow paths that supply refrigerant from the branch point BR to the sub-junction points C1, C2, which are junctions with the sub-flow paths 271f, 272f. The second main flow paths 271b, 272b are flow paths that supply refrigerant from the sub-junction points C1, C2 to the pumps 211, 212. The third main flow paths 271c, 272c are flow paths that supply refrigerant from the pumps 211, 212 to the fuel cell stacks 11, 12. The fourth main flow paths 271d, 272d are flow paths that supply refrigerant from the fuel cell stacks 11, 12 to the rotary valves 291, 292. The fifth main flow paths 271e, 272e are flow paths that supply refrigerant from the rotary valves 291, 292 to the main junction point CT. The sub-flow paths 271f and 272f are flow paths that supply the refrigerant from the rotary valves 291 and 292 to the sub-junctions C1 and C2 without passing through the radiator 210.

[0016] The rotary valves 291, 292 are three-way valves that switch the refrigerant flow path between a circulation path that passes through the fuel cell stacks 11, 12 and the radiator 210 and a bypass path that passes through the fuel cell stacks 11, 12 without passing through the radiator 210. The circulation path is a path formed by the common flow paths 261, 262, the first main flow paths 271a, 272a, the second main flow paths 271b, 272b, the third main flow paths 271c, 272c, the fourth main flow paths 271d, 272d, and the fifth main flow paths 271e, 272e. The bypass path is a path formed by the sub-flow paths 271f, 272f, the second main flow paths 271b, 272b, the third main flow paths 271c, 272c, and the fourth main flow paths 271d, 272d. The first rotary valve 291 adjusts the flow rate ratio between the flow rate of refrigerant supplied from the fourth main flow path 271d to the fifth main flow path 271e among the first individual flow paths 271a to 271f and the flow rate of refrigerant supplied from the fourth main flow path 271d to the sub-flow path 271f. The second rotary valve 292 adjusts the flow rate ratio between the flow rate of refrigerant supplied from the fourth main flow path 272d to the fifth main flow path 272e among the second individual flow paths 272a to 272f and the flow rate of refrigerant supplied from the fourth main flow path 272d to the sub-flow path 272f.

[0017] 2 is a block diagram showing the configuration of the cooling control device 50. The cooling control device 50 controls the operation of the cooling device 20. The cooling control device 50 includes a processor 501, a memory 502, an input / output interface 503, and a bus 504. The processor 501, the memory 502, and the input / output interface 503 are connected via the bus 504 to enable bidirectional communication. A communication device 505 is connected to the input / output interface 503 to communicate with the cooling device 20. The communication device 505 can communicate with the cooling device 20 via wired communication or wireless communication.

[0018] By executing the program PG stored in the memory 502, the processor 501 functions as an actual flow rate calculation unit 511, a radiator flow rate calculation unit 512, a common pressure loss calculation unit 513, an individual pressure loss calculation unit 514, and an operation control unit 515.

[0019] The actual flow rate calculation unit 511 calculates the actual pump flow rate for each of the pumps 211 and 212. The actual pump flow rate is the amount of refrigerant actually discharged from the pumps 211 and 212 per unit time.

[0020] Radiator flow rate calculation unit 512 calculates the radiator flow rate using the sum of the actual pump flow rates of pumps 211 and 212. The radiator flow rate is the amount of refrigerant passing through radiator 210 per unit time.

[0021] The common pressure loss calculation unit 513 calculates the common pressure loss using the radiator flow rate. The common pressure loss is the pressure loss in the common flow paths 261 and 262.

[0022] The individual pressure loss calculation unit 514 calculates the individual pressure loss for each of the fuel cell stacks 11, 12. The individual pressure loss is the pressure loss for each of the individual flow paths 271a to 271f, 272a to 272f corresponding to each of the two fuel cell stacks 11, 12.

[0023] The operation control unit 515 operates each pump 211, 212 using the total pressure loss and the required pump flow rate for each pump 211, 212. The total pressure loss is a pressure loss calculated by summing the common pressure loss and the individual pressure losses for the individual flow paths 271a-271f, 272a-272f corresponding to the fuel cell stacks 11, 12 corresponding to the target pumps 211, 212. The required pump flow rate is the amount of refrigerant that is required to be discharged from the pumps 211, 212 per unit time.

[0024] The fuel cell stacks 11, 12 are cooled to a desired temperature by adjusting at least one of the flow rate of the pumps 211, 212, which is determined by the rotation speed and head of the pumps 211, 212, and the opening of the rotary valves 291, 292. In other words, there is a correlation between the rotation speed of the pumps 211, 212, the head of the pumps 211, 212, the flow rate of the pumps 211, 212, and the opening of the rotary valves 291, 292. Therefore, by preparing characteristic maps M1, M2 in advance that represent the correlation between the rotation speed of the pumps 211, 212, the head of the pumps 211, 212, the flow rate of the pumps 211, 212, and the opening of the rotary valves 291, 292, the following can be achieved. When at least one of the rotation speed of the pumps 211, 212, the head of the pumps 211, 212, the flow rate of the pumps 211, 212, and the opening of the rotary valves 291, 292 is unknown, the unknown can be calculated by applying the known values ​​to the characteristic maps M1, M2.

[0025] FIG. 3 is a conceptual diagram of characteristic maps M1 and M2. The vertical axis of FIG. 3 represents pump head. The horizontal axis of FIG. 3 represents pump flow rate. The constant rotation speed line L1 shows the correlation between pump head and pump flow rate when the rotation speed of pumps 211 and 212 is kept constant and the opening of rotary valves 291 and 292 is changed. The constant opening line L2 shows the correlation between pump head and pump flow rate when the rotation speed of pumps 211 and 212 is kept constant and the opening of rotary valves 291 and 292 is changed. The characteristic maps M1 and M2 are prepared in advance for each pump 211 and 212 and stored in memory 502 shown in FIG. 1. The first characteristic map M1 represents the operating characteristics of the first pump 211. The second characteristic map M2 represents the operating characteristics of the second pump 212.

[0026] 4 is a flowchart showing a cooling control method for two fuel cell stacks 11, 12 connected in parallel to a common radiator 210 by a refrigerant passage 250. The flow shown in FIG. 4 is executed repeatedly at predetermined intervals, for example, during the period when power is generated using the fuel cell stacks 11, 12.

[0027] In step S1, the actual flow rate calculation unit 511 calculates the actual pump flow rate for the first pump 211 and the actual pump flow rate for the second pump 212. Here, the head of the pumps 211, 212 is the pressure difference obtained by subtracting the inflow pressure when the refrigerant flows into the pumps 211, 212 from the discharge pressure when the refrigerant is discharged from the pumps 211, 212, and is equal to the total pressure loss. Therefore, the actual flow rate calculation unit 511 applies the rotation speed of the first pump 211 at a specific time point before the calculation of the actual pump flow rate, the total pressure loss for the first fuel cell stack 11 at the specific time point, and the opening degree of the first rotary valve 291 at the specific time point to a first characteristic map M1. As a result, the actual flow rate calculation unit 511 calculates the actual pump flow rate for the first pump 211. Similarly, the actual flow rate calculation unit 511 applies the rotation speed of the second pump 212 at a specific time point, the total pressure loss for the second fuel cell stack 12 at the specific time point, and the opening degree of the second rotary valve 292 at the specific time point to the second characteristic map M2. In this way, the actual flow rate calculation unit 511 calculates the actual pump flow rate for the second pump 212. The rotation speed of each pump 211, 212 is measured, for example, by a sensor (not shown) and output to the cooling control device 50. The total pressure loss at the specific time point is, for example, the previous value of the total pressure loss for the target fuel cell stacks 11, 12. The previous value of the total pressure loss is the value of the total pressure loss calculated at the previous control timing in step S5, which will be described later. Note that when the flow shown in FIG. 3 is executed for the first time, the pumps 211, 212 are not rotating, and therefore the total pressure loss at the specific time point is zero.

[0028] In step S2, the radiator flow rate calculation unit 512 calculates the radiator flow rate. As shown in Fig. 1, the radiator 210 receives the coolant discharged from the first fuel cell stack 11 and the coolant discharged from the second fuel cell stack 12. Therefore, the radiator flow rate calculation unit 512 calculates the sum of the actual pump flow rate for the first pump 211 and the actual pump flow rate for the second pump 212 as the radiator flow rate.

[0029] In step S3, the common pressure loss calculation unit 513 calculates the common pressure loss. Here, there is a correlation between the dynamic pressure, which indicates the kinetic energy of the refrigerant per unit area, and the pressure loss. The dynamic pressure is proportional to the density of the refrigerant and the flow rate of the refrigerant. Furthermore, there is a correlation between the flow rate of the refrigerant and the flow velocity of the refrigerant. Therefore, the pressure loss can be calculated by multiplying the flow rate of the refrigerant by a predetermined pressure loss coefficient. Pressure loss occurs every time the refrigerant passes through each of the flow paths 261, 262, 271a-271f, 272a-272f and each of the devices 11, 12, 210, 211, 212, 291, and 292. Therefore, the common pressure loss calculation unit 513 calculates the pressure loss occurring when the refrigerant passes through the first common flow path 261 by multiplying the radiator flow rate by the pressure loss coefficient corresponding to the first common flow path 261. The common pressure loss calculation unit 513 calculates the pressure loss that occurs when the refrigerant passes through the radiator 210 by multiplying the radiator flow rate by a pressure loss coefficient corresponding to the radiator 210. The common pressure loss calculation unit 513 calculates the pressure loss that occurs when the refrigerant passes through the second common flow path 262 by multiplying the radiator flow rate by a pressure loss coefficient corresponding to the second common flow path 262. The common pressure loss calculation unit 513 then calculates the common pressure loss by adding up the pressure losses that occur when the refrigerant passes through each of the common flow paths 261, 262 and the pressure loss that occurs when the refrigerant passes through the radiator 210. When the refrigerant is flowing through the sub-flow paths 271f, 272f, the common pressure loss calculation unit 513 calculates the common pressure loss by taking into account the openings of the rotary valves 291, 292.

[0030] In step S4, the individual pressure loss calculation unit 514 calculates the individual pressure losses for the first individual flow paths 271a-271f and the individual pressure losses for the second individual flow paths 272a-272f. The individual pressure loss calculation unit 514 calculates the pressure loss occurring when the refrigerant passes through the first main flow path 271a by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the first main flow path 271a. The individual pressure loss calculation unit 514 calculates the pressure loss occurring when the refrigerant passes through the second main flow path 271b by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the second main flow path 271b. The individual pressure loss calculation unit 514 calculates the pressure loss occurring when the refrigerant passes through the first pump 211 by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the first pump 211. The individual pressure loss calculation unit 514 calculates the pressure loss that occurs when the refrigerant passes through the third main flow path 271c by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the third main flow path 271c. The individual pressure loss calculation unit 514 calculates the pressure loss that occurs when the refrigerant passes through the first fuel cell stack 11 by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the first fuel cell stack 11. The individual pressure loss calculation unit 514 calculates the pressure loss that occurs when the refrigerant passes through the fourth main flow path 271d by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the first rotary valve 291. The individual pressure loss calculation unit 514 calculates the pressure loss that occurs when the refrigerant passes through the first rotary valve 291 by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the first rotary valve 291. The individual pressure loss calculation unit 514 calculates the pressure loss that occurs when the refrigerant passes through the fifth main flow path 271e by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the fifth main flow path 271e. The individual pressure loss calculation unit 514 calculates the pressure loss that occurs when the refrigerant passes through the sub-flow path 271f by multiplying the actual pumping flow rate of the first pump 211 by a pressure loss coefficient corresponding to the sub-flow path 271f.The individual pressure loss calculation unit 514 calculates the individual pressure loss for the first individual flow paths 271a-271f by adding up the pressure loss that occurs when the refrigerant passes through the first individual flow paths 271a-271f and the pressure loss that occurs when the refrigerant passes through each of the devices 11, 211, and 291. Similarly, the individual pressure loss calculation unit 514 calculates the individual pressure loss for the second individual flow paths 272a-272f by adding up the pressure loss that occurs when the refrigerant passes through the second individual flow paths 272a-272f and the pressure loss that occurs when the refrigerant passes through each of the devices 12, 212, and 292. When the refrigerant is flowing through the sub-flow paths 271f and 272f, the individual pressure loss calculation unit 514 calculates the individual pressure loss by taking into account the openings of the rotary valves 291 and 292.

[0031] In step S5, the operation control unit 515 sets the rotation speed of the first pump 211 and the rotation speed of the second pump 212, and operates each pump 211, 212 at the set rotation speed. The operation control unit 515 applies the total pressure loss, which is the sum of the common pressure loss and the individual pressure losses for the first individual flow paths 271a to 271f, the required pump flow rate of the first pump 211, and the opening of the first rotary valve 291, to a first characteristic map M1. In this way, the operation control unit 515 calculates and sets the rotation speed of the first pump 211. The operation control unit 515 applies the total pressure loss, which is the sum of the common pressure loss and the individual pressure losses for the second individual flow paths 272a to 272f, the required pump flow rate of the second pump 212, and the opening of the second rotary valve 292, to a second characteristic map M2. As a result, the operation control unit 515 calculates and sets the rotation speed of the second pump 212. The required pump flow rate is determined according to the temperature of the fuel cell stacks 11, 12. Therefore, the operation control unit 515 calculates an estimated value for the temperature of the coolant discharged from the fuel cell stacks 11, 12, for example, by subtracting the amount of heat dissipated to the outside through the piping that constitutes the coolant passage 250 from the coolant temperature output from the temperature sensors 231, 232. Then, the operation control unit 515 determines the required pump flow rate based on the estimated value for the coolant temperature.

[0032] According to the above embodiment, the cooling control device 50 can individually set and operate the rotation speed of each pump 211, 212 using the pressure loss when the refrigerant passes through the refrigerant passage 250 and the required pump flow rate for each pump 211, 212. This increases the likelihood that a refrigerant at a flow rate appropriate for each fuel cell stack 11, 12 can be supplied to each fuel cell stack 11, 12, compared to when the rotation speeds of each pump 211, 212 are set uniformly. In this case, the cooling control device 50 can calculate the radiator flow rate using the sum of the actual pump flow rates for each pump 211, 212, and then calculate the common pressure loss using the radiator flow rate. In other words, the cooling control device 50 can calculate the common pressure loss by treating the common flow paths 261, 262 as a single system common to the two fuel cell stacks 11, 12. This reduces the control load when setting the rotation speeds of the pumps 211, 212, while ensuring cooling accuracy.

[0033] Furthermore, according to the above embodiment, the cooling control device 50 can calculate the actual pump flow rate using the rotation speed of the pumps 211, 212 at a specific time point prior to the calculation of the actual pump flow rate and the total pressure loss at the specific time point. The cooling control device 50 can calculate the rotation speed of the pumps 211, 212 by applying the total pressure loss and the required pump flow rate to characteristic maps M1, M2 prepared in advance. The cooling control device 50 can calculate the common pressure loss by multiplying the radiator flow rate by a predetermined pressure loss coefficient. The cooling control device 50 can calculate the individual pressure loss by multiplying the actual pump flow rate of the corresponding pump 211, 212 by a predetermined pressure loss coefficient.

[0034] B. Other Embodiments: (B1) The cooling control device 50 may control the cooling of one of the fuel cell stacks 11, 12 among multiple fuel cell stacks 11, 12 connected to a common radiator 210 by a refrigerant passage 250. In this case, the cooling control device 50 calculates the common pressure loss by regarding the actual pump flow rate of one pump 211, 212 provided for the target one fuel cell stack 11, 12 as the radiator flow rate. In this configuration, the cooling control device 50 can control the cooling of any one of the fuel cell stacks 11, 12 among the multiple fuel cell stacks 11, 12 connected to the common radiator 210 by a refrigerant passage 250.

[0035] (B2) The cooling control device 50 may control the cooling of three or more fuel cell stacks 11, 12 connected in parallel to a common radiator 210 by the refrigerant passages 250. In this case, the cooling control device 50 calculates the common pressure loss using the sum of the actual pump flow rates of all of the pumps 211, 212 provided for all of the target fuel cell stacks 11, 12 as the radiator flow rate. In this configuration, the cooling control device 50 can control the cooling of three or more fuel cell stacks 11, 12 connected in parallel to a common radiator 210 by the refrigerant passages 250.

[0036] (B3) The cooling control device 50 may use a method other than those described above to calculate the actual pump flow rate, rotation speed, common pressure loss, and individual pressure loss of each of the pumps 211, 212. For example, the cooling control device 50 may calculate the rotation speed of the pumps 211, 212 using a table or a relational expression that represents the correlation between the rotation speed of the pumps 211, 212, the head of the pumps 211, 212, the flow rate of the pumps 211, 212, and the opening of the rotary valves 291, 292.

[0037] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0038] 1...cooling system, 11...first fuel cell stack, 12...second fuel cell stack, 20...cooling device, 50...cooling control device, 210...radiator, 211...first pump, 212...second pump, 231...first temperature sensor, 232...second temperature sensor, 250...refrigerant passage, 261...first common flow path, 262...second common flow path, 271a, 272a...first main flow path, 271b, 272b...second main flow path, 271c, 272c...third main flow path, 271d, 272d...fourth main flow path, 271e, 272e...fifth main flow path, 271f , 272f... sub-flow path, 291... first rotary valve, 292... second rotary valve, 501... processor, 502... memory, 503... input / output interface, 504... bus, 505... communication device, 511... actual flow rate calculation unit, 512... radiator flow rate calculation unit, 513... common pressure loss calculation unit, 514... individual pressure loss calculation unit, 515... operation control unit, BR... branch point, C1, C2... sub-junction point, CT... main junction point, L1... constant rotation speed line, L2... constant opening line, M1... first characteristic map, M2... second characteristic map, PG... program

Claims

1. A cooling control method for a plurality of fuel cell stacks connected in parallel to a common radiator by coolant passages through which a coolant flows, comprising: a pump for circulating the coolant between the fuel cell stack and the radiator is provided in the coolant passage for each of the plurality of fuel cell stacks; The cooling control method includes: (a) calculating an actual pump flow rate for each of the pumps; (b) calculating a radiator flow rate using the sum of the actual pump flow rates for each of the pumps; (c) calculating a common pressure loss, which is a pressure loss in a common flow path of the refrigerant passages that is common to the plurality of fuel cell stacks, using the radiator flow rate; (d) calculating an individual pressure loss, which is the pressure loss for each individual flow path of the refrigerant passage corresponding to each of the plurality of fuel cell stacks; (e) A cooling control method comprising a step of operating each of the pumps using a total pressure loss obtained by adding up the common pressure loss and the individual pressure loss and a required pump flow rate for each of the pumps.

2. 2. The cooling control method according to claim 1, In the step (a), the actual pump flow rate is calculated using the pump rotation speed at a specific time point prior to the calculation of the actual pump flow rate and the total pressure loss at the specific time point.

3. 2. The cooling control method according to claim 1, In the step (e), the rotation speed of the pump is calculated by applying the total pressure loss and the required pump flow rate to a characteristic map prepared in advance; The cooling control method, wherein the characteristic map represents a correlation between a pump flow rate, the total pressure loss, and the rotation speed of the pump.

4. 2. The cooling control method according to claim 1, In the step (c), the common pressure loss is calculated by multiplying the radiator flow rate by a predetermined pressure loss coefficient, In the step (d), the individual pressure losses are calculated by multiplying the actual pump flow rates of the corresponding pumps by predetermined pressure loss coefficients.

5. A cooling control device for a plurality of fuel cell stacks connected in parallel to a common radiator by coolant passages through which a coolant flows, a pump for circulating the coolant between the fuel cell stack and the radiator is provided in the coolant passage for each of the plurality of fuel cell stacks; The cooling control device includes: an actual flow rate calculation unit that calculates an actual pump flow rate for each of the pumps; a radiator flow rate calculation unit that calculates a radiator flow rate using the sum of the actual pump flow rates for each of the pumps; a common pressure loss calculation unit that calculates a common pressure loss, which is a pressure loss in a common flow path among the refrigerant passages that is common to the plurality of fuel cell stacks, using the radiator flow rate; an individual pressure loss calculation unit that calculates an individual pressure loss, which is a pressure loss for each individual flow path of the refrigerant passages corresponding to each of the plurality of fuel cell stacks; a cooling control device comprising: an operation control unit that operates each of the pumps using a total pressure loss that is the sum of the common pressure loss and the individual pressure loss and a required pump flow rate for each of the pumps.

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