JP2024016591A - Fuel battery system - Google Patents

Abstract

To provide a technique which can reduce the time that a fuel battery system needs for a warm-up operation.SOLUTION: The fuel cell system according to the present specification includes: a cooling circuit having a first flow passage and a second flow passage connected in parallel to each other; a fuel battery provided in the first flow passage; a power consumption unit in the second flow passage, the power consumption unit being capable of consuming power generated in the fuel battery; at least one circulation control apparatus in the cooling circuit, the at least one circulation control apparatus controlling a circulation route for cooling water; and a control unit for executing a first warm-up operation by controlling the fuel battery, and power consumption unit, and at least one circulation control apparatus. In the first warm-up operation, cooling water circulates in the first flow passage and in the second flow passage, the fuel battery generates power, and the power consumption unit consumes a part of power generated by the fuel battery.SELECTED DRAWING: Figure 2

Description

The technology disclosed herein relates to a fuel cell system.

Patent Document 1 discloses a fuel cell system. This fuel cell system includes a fuel cell and a cooling circuit for cooling the fuel cell.

JP 2021-111488 Publication

In a fuel cell system, if the temperature of the cooling water in the cooling circuit is too low, the performance of the fuel cell may deteriorate. Therefore, if the temperature of the cooling water is too low when starting the fuel cell system, a warm-up operation is performed to raise the temperature of the cooling water to an appropriate temperature. The shorter the time required for warm-up, the better. This specification provides a technique that can reduce the time required for warm-up operation (also referred to as "warm-up time" in this specification).

A fuel cell system disclosed in this specification includes a cooling circuit including a first flow path and a second flow path connected in parallel to each other, a fuel cell provided in the first flow path, and a cooling circuit that includes a first flow path and a second flow path connected to each other in parallel. a power consumption unit that is provided in the fuel cell and is capable of consuming power generated by the fuel cell; at least one circulation control device that is provided in the cooling circuit and controls a circulation path of the cooling water; A control unit capable of executing a first warm-up operation by controlling operations of a battery, the power consumption unit, and the at least one circulation control device. In the first warm-up operation, the cooling water circulates in both the first flow path and the second flow path, the fuel cell generates power, and a part of the power generated by the fuel cell is transferred to the electric power. Consumed in consumption units.

During warm-up operation of a fuel cell system, a typical configuration is such that the temperature of cooling water is raised using heat generated as a result of power generation by the fuel cell. On the other hand, according to the above configuration, during warm-up operation, not only the heat generated by the power generation of the fuel cell but also the heat generated by the power consumption of the power consumption unit is used to cool the cooling water. Increase temperature. Therefore, the temperature of the cooling water can be raised efficiently, and the warm-up time can be reduced.

In a fuel cell system, if the fuel cell generates more power than can be consumed by the fuel cell system, problems (for example, battery deterioration) occur. For this reason, it is preferable that the output (generated power) of the fuel cell is suppressed to an extent that does not exceed the power consumption of the fuel cell system. According to the above configuration, during warm-up operation, part of the power generated by the fuel cell is consumed by the power consumption unit. Therefore, the power consumption of the fuel cell system can be increased compared to the case where the power generated by the fuel cell is not consumed by the power consumption unit. Thereby, the output of the fuel cell can be increased more than usual. Therefore, according to the above configuration, it is possible to increase the heat generated by the power generation of the fuel cell more than usual, so that the warm-up time can be reduced.

FIG. 1 is a diagram schematically showing the configuration of a vehicle 100 according to an example. 1 is a diagram schematically showing the configuration of a cooling circuit 10 of an FC system 2 according to an example. FIG. 6 is a diagram showing current-voltage characteristics of the FC stack 4 when a first warm-up operation is performed by increasing the FC output iv to the output upper limit _P1 in the FC system 2 according to the embodiment. FIG. 7 is a diagram showing current-voltage characteristics of the FC stack 4 when a second warm-up operation is performed by increasing the FC output iv to the output upper limit _P2 in the FC system 2 according to the embodiment. It is a flowchart which shows the process which ECU8 based on an Example performs.

Representative and non-limiting specific examples of the present invention will be described in detail below with reference to the drawings. This detailed description is merely intended to provide those skilled in the art with details for implementing the preferred embodiment of the invention, and is not intended to limit the scope of the invention. Additionally, the additional features and inventions disclosed can be used separately or in conjunction with other features and inventions to provide further improved fuel cell systems.

Furthermore, the features and combinations of steps disclosed in the following detailed description are not essential to practicing the invention in its broadest sense, and are intended solely for the purpose of specifically illustrating representative embodiments of the invention. shall be described. Moreover, various features of the exemplary embodiments below, as well as those recited in the claims, are described herein in providing additional and useful embodiments of the invention. They do not have to be combined exactly as shown in the specific examples or in the order listed.

All features recited in the specification and/or claims are included in the original disclosure and in the claims, independently of the embodiments and/or the features recited in the claims. are intended to be disclosed separately and independently of each other as limitations to the specific matters identified. Furthermore, all references to numerical ranges and groups or populations are intended to be used as limitations on the specific subject matter recited in the original disclosure and claims, and are intended to disclose intermediate configurations thereof.

In one or more embodiments, the control unit may be further capable of performing a second warm-up operation. In the second warm-up operation, the cooling water circulates in the first flow path, the cooling water does not circulate in the second flow path, and the fuel cell generates power, and the power generated by the fuel cell may not be consumed in the power consuming unit.

The second warm-up operation in the above configuration is a general warm-up operation. As described above, in the first warm-up operation, the warm-up time can be reduced compared to the second warm-up operation. However, the first warm-up operation consumes more fuel than the second warm-up operation. In some cases, the second warm-up operation may be better than the first warm-up operation. Therefore, in the fuel cell system, it is desirable that the warm-up operation is switched between the first warm-up operation and the second warm-up operation depending on the situation. According to the above configuration, the control unit can switch the warm-up operation between the first warm-up operation and the second warm-up operation depending on the situation.

In one or more embodiments, the control unit detects the temperature of the cooling water during startup of the fuel cell system, and starts the first warm-up operation when the detected temperature is below a predetermined temperature. The second warm-up operation may be performed when the detected temperature exceeds the predetermined temperature.

Generally, the lower the temperature of the cooling water, the longer the warm-up time because it takes longer to raise the temperature of the cooling water. Therefore, when the temperature of the cooling water is very low (for example, −20° C.), it is necessary to reduce the warm-up time even if a large amount of fuel is consumed. On the other hand, when the temperature of the cooling water is relatively high (for example, 5° C.), it is necessary to suppress fuel consumption rather than reducing the warm-up time. Therefore, in the fuel cell system, it is desirable that the warm-up operation is switched between the first warm-up operation and the second warm-up operation depending on the temperature of the cooling water. According to the above configuration, when the temperature of the cooling water is lower than the predetermined temperature, the control unit executes the first warm-up operation that can reduce the warm-up time, and when the temperature of the cooling water is higher than the predetermined temperature, the control unit executes the first warm-up operation that can reduce the warm-up time. A second warm-up operation is performed in which the amount of consumption is relatively small. In this way, the control unit can switch the warm-up operation between the first warm-up operation and the second warm-up operation depending on the temperature of the cooling water.

In one or more embodiments, the theoretical value of the electromotive force of the fuel cell is v ₀ , the actual value of the electromotive force of the fuel cell is v 0 , and the cooling water is circulated in the first flow path and the electromotive force of the fuel cell is The heat capacity of the cooling circuit when the cooling water does not circulate in the two flow paths is C ₁ , and the heat capacity of the cooling circuit when the cooling water circulates in both the first flow path and the second flow path is C ₁ +C ₂ , and when the output upper limit value of the fuel cell in the second warm-up operation is P ₂ , the power consumption P _BR of the power consumption unit in the first warm-up operation may satisfy the following formula.

In the second warm-up operation, the cooling water is not circulated or heated in the second flow path. On the other hand, in the first warm-up operation, the cooling water is circulated and the temperature is increased in the second flow path as well. Therefore, the heat capacity when performing the first warm-up operation is larger by the amount related to the second flow path (that is, larger by _C2 ) than the heat capacity when performing the second warm-up operation. Therefore, even if the first warm-up operation is executed, if the power consumption _PBR in the power consumption unit is small, the warm-up time will be longer than when the second warm-up operation is executed. It will increase. From the above, in order to appropriately exhibit the effect of reducing the warm-up time based on the configuration of the present application, it is necessary to make the power consumption _PBR sufficiently large. Although the details will be described later, according to the above configuration, the power consumption _PBR can be sufficiently increased, so that the effect of reducing the warm-up time based on the configuration of the present application can be appropriately exhibited.

In one or more embodiments, an actual measured value of the electromotive force of the fuel cell is v, an output upper limit value of the fuel cell in the second warm-up operation is P ₂ , and an upper current limit of the fuel cell based on frost heaving constraints. When the value is i _max , the power consumption P _BR of the power consumption unit in the first warm-up operation may satisfy the following formula.

Typically, fuel cells are configured to generate electricity by causing a chemical reaction between hydrogen and oxygen. Therefore, in a fuel cell, as the current value of the fuel cell increases, more hydrogen and oxygen are consumed and more water is generated. Furthermore, in low-temperature conditions such as during warm-up operation, water generated in the fuel cell may freeze. When a large amount of water is instantaneously generated in a fuel cell, ice blocks may form between the fuel cells (this phenomenon is called "frost heave"). If frost heaving occurs, there is a risk of damaging battery cells. Therefore, in the fuel cell, an upper limit value (current upper limit value i _max of the fuel cell based on the frost heave constraint) is set for the current value of the fuel cell in order to suppress the frost heaving phenomenon. Although details will be described later, according to the above configuration, by reducing the power consumption _PBR , it is possible to suppress the current value of the fuel cell from reaching the current upper limit value _imax . Thereby, frost heave phenomenon can be suppressed.

In one or more embodiments, the fuel cell system may be mounted on a vehicle that includes a traction motor that drives wheels. The power consumption unit may be a brake resistor that consumes power generated when the travel motor dynamically brakes the wheels.

According to the above configuration, a brake resistor provided in a vehicle can be used as a power consumption unit. Therefore, there is no need to provide a dedicated part to the vehicle, and the configuration of the present application can be easily implemented.

(Example)
As shown in FIG. 1, the fuel cell system of this embodiment (hereinafter referred to as "FC system 2") is mounted on a vehicle 100. In addition to the FC system 2, the vehicle 100 includes a pair of front wheels 102, a pair of rear wheels 104, a running motor 106 connected to the pair of rear wheels 104, and an electrically connected drive motor 106. A battery 108 is provided. The driving motor 106 is electrically connected to the fuel cell stack (hereinafter referred to as "FC stack 4") of the FC system 2 and the brake resistor 6, respectively. The battery 108 is a rechargeable secondary battery (for example, a lithium ion battery) and is electrically connected to the FC stack 4 of the FC system 2. The FC stack 4 and the brake resistor 6 are electrically connected to each other. The FC system 2 includes an ECU (Electronic Control Unit) 8 in addition to an FC stack 4 and a brake register 6. The ECU 8 is a type of computer device that includes a processor and a memory. ECU 8 controls the electrical system of vehicle 100. That is, the ECU 8 can control the operations of the FC system 2, the driving motor 106, the battery 108, and the like. Although not shown, the vehicle 100 further includes a hydrogen tank that stores hydrogen to be supplied to the FC stack 4 and an air compressor that supplies air (particularly oxygen) to the FC stack 4.

The FC stack 4 includes a plurality of fuel cells (not shown). Each fuel cell generates electricity by chemically reacting hydrogen and oxygen. That is, the FC stack 4 generates power by converting chemical energy contained in hydrogen and oxygen into electrical energy. Here, if the theoretical value of the electromotive force of the FC stack 4 is _v0 , the actual value of the electromotive force of the FC stack 4 is v, and the current value (FC current value) of the FC stack 4 is i, then The generated power (FC output) is estimated to be iv. In this embodiment, it is assumed that the energy loss that is not converted into electrical energy in the FC stack 4 is converted into thermal energy. Therefore, the calorific value of the FC stack 4 (FC calorific value) is estimated to be i(v ₀ −v).

The driving motor 106 is operated by electric power supplied from the battery 108 and the FC stack 4, and rotationally drives the pair of rear wheels 104. The driving motor 106 can also dynamically brake the pair of rear wheels 104 by converting its own kinetic energy into electric power. When the driving motor 106 dynamically brakes the pair of rear wheels 104, the power generated by the driving motor 106 is normally charged into the battery 108. However, when the battery 108 is nearly fully charged, the electric power generated by the driving motor 106 is supplied to the brake register 6 and is consumed as thermal energy. This suppresses excessive charging of the battery 108.

As shown in FIG. 2, the FC system 2 includes a cooling circuit 10 for cooling the FC stack 4 and the brake register 6. The cooling circuit 10 includes a first flow path 11 , a second flow path 12 , a third flow path 13 , a fourth flow path 14 , a fifth flow path 15 , and a sixth flow path 16 . The first flow path 11 is provided with an FC stack 4, a first pump 22, and a first check valve 24. The FC stack 4 is provided downstream of the first pump 22. The first check valve 24 is provided on the downstream side of the FC stack 4. Further, the first flow path 11 is provided with a bypass flow path 11 a that bypasses the FC stack 4 on the downstream side of the first pump 22 and upstream of the first check valve 24 . In this embodiment, the bypass flow path 11a is a part of the first flow path 11. An intercooler 26 is provided in the bypass passage 11a. The intercooler 26 exchanges heat between air supplied to the FC stack 4 from an air compressor (not shown) and cooling water flowing through the bypass flow path 11a. Further, the second flow path 12 is provided with a brake resistor 6, a second pump 28, and a second check valve 30. The brake resistor 6 is provided downstream of the second pump 28. The second check valve 30 is provided downstream of the brake register 6. The first flow path 11 and the second flow path 12 are connected in parallel to each other.

The upstream ends of the first flow path 11 and the second flow path 12 are connected to the downstream end of the third flow path 13 . The upstream end of the fourth flow path 14 is connected to the downstream ends of the first flow path 11 and the second flow path 12 . A downstream end of the fourth flow path 14 is connected to a three-way valve 32. The three-way valve 32 is also connected to the upstream end of the fifth flow path 15 and the upstream end of the sixth flow path 16. The three-way valve 32 can be switched between a first communication state in which the fourth flow path 14 is connected to the fifth flow path 15 and a second communication state in which the fourth flow path 14 is connected to the sixth flow path 16. be. Further, the fifth channel 15 is provided with an ion exchanger 34 . The ion exchanger 34 is a device for purifying the cooling water flowing through the fifth channel 15. Furthermore, a radiator 36 is provided in the sixth flow path 16 . The radiator 36 radiates heat absorbed from the cooling water. The downstream end of the fifth flow path 15 and the downstream end of the sixth flow path 16 are both connected to the upstream end of the third flow path 13.

Although not shown, the cooling circuit 10 is provided with a temperature sensor that detects the temperature of cooling water. A plurality of temperature sensors may be provided, including the first flow path 11, the second flow path 12, the third flow path 13, the fourth flow path 14, the fifth flow path 15, and the sixth flow path. It may be provided in each of the paths 16. The ECU 8 can detect the temperature of the cooling water at a desired position in the cooling circuit 10 based on these temperature sensors.

(Warm-up operation of cooling circuit 10)
The ECU 8 is configured to perform a warm-up operation of the cooling circuit 10 when the power of the vehicle 100 is turned on and the FC system 2 is started. At this time, the ECU 8 is configured to select and execute either the first warm-up operation or the second warm-up operation. Note that during the warm-up operation, the power generation efficiency v/v ₀ is intentionally lowered in order to increase the FC calorific value i (v ₀ −v). Therefore, during the warm-up operation, the power generation efficiency v/v ₀ is regarded as a constant. Further, since the theoretical value v ₀ of the electromotive force of the FC stack 4 is a constant, the measured value v of the electromotive force of the FC stack 4 is also regarded as a constant.

In the first warm-up operation, the ECU 8 drives the first pump 22 and the second pump 28 while placing the three-way valve 32 in the first communicating state. Thereby, cooling water circulates through the first flow path 11 , the second flow path 12 , the third flow path 13 , the fourth flow path 14 , and the fifth flow path 15 in the cooling circuit 10 . The ECU 8 also causes the FC stack 4 to generate electricity. The power generated by the FC stack 4 is supplied to each part of the vehicle 100 and consumed in each part of the vehicle 100. At this time, a part of the power generated by the FC stack 4 is supplied to the brake register 6 and consumed as thermal energy.

In the first warm-up operation, the cooling water flowing through the first flow path 11, the second flow path 12, the third flow path 13, the fourth flow path 14, and the fifth flow path 15 is (v ₀ −v) and the heat generation amount (BR heat generation amount) H _BR of the brake resistor 6 are added. That is, in the first warm-up operation, the cooling water is heated using the heat generated as the FC stack 4 generates power and the heat generated as the brake register 6 consumes power.

In the first warm-up operation, the output upper limit value _P1 of the FC stack 4 is set. The output upper limit value _P1 is the sum of the power consumed by each part of the vehicle 100 except the battery 108 during execution of the first warm-up operation. In the first warm-up operation, the ECU 8 increases the FC output iv to the output upper limit value _P1 , while suppressing the FC output iv from exceeding the output upper limit value _P1 . Thereby, the FC heat generation amount i (v ₀ -v) can be increased as much as possible while suppressing overcharging of the battery 108.

FIG. 3 shows the current-voltage characteristics of the FC stack 4 when the first warm-up operation is performed by increasing the FC output iv to the output upper limit value _P1 . During warm-up operation, the measured value v of the electromotive force of the FC stack 4 is regarded as a constant, so when increasing the FC output iv to the output upper limit value P ₁ , the FC current value i is i ₁ = P ₁ / It is raised to v. In FIG. 3, the FC calorific value i ₁ (v ₀ -v) in this case is shown as H ₁ . Therefore, the following equation (1) holds true between P ₁ and H ₁ .

In the second warm-up operation, the ECU 8 drives the first pump 22 while placing the three-way valve 32 in the first communicating state. ECU 8 does not drive second pump 28. Thereby, cooling water circulates through the first flow path 11 , the third flow path 13 , the fourth flow path 14 , and the fifth flow path 15 in the cooling circuit 10 . Further, the ECU 8 causes the FC stack 4 to generate electricity. The power generated by the FC stack 4 is supplied to each part of the vehicle 100 and consumed in each part of the vehicle 100. At this time, the power generated by the FC stack 4 is not supplied to the brake register 6.

In the second warm-up operation, the cooling water flowing through the first flow path 11, the third flow path 13, the fourth flow path 14, and the fifth flow path 15 has an FC calorific value i(v ₀ −v). Added. That is, in the second warm-up operation, the cooling water is heated using the heat generated as the FC stack 4 generates electricity.

In the second warm-up operation, the output upper limit value _P2 of the FC stack 4 is set. The output upper limit value _P2 is a value that is the sum of the power consumed by each part of the vehicle 100 except the battery 108 during execution of the second warm-up operation. In the second warm-up operation, the ECU 8 increases the FC output iv to the output upper limit value _P2 , while suppressing the FC output iv from exceeding the output upper limit value _P2 . Thereby, the FC heat generation amount i (v ₀ -v) can be increased as much as possible while suppressing overcharging of the battery 108.

FIG. 4 shows the current-voltage characteristics of the FC stack 4 when the second warm-up operation is performed by increasing the FC output iv to the output upper limit value _P2 . During warm-up operation, the measured value v of the electromotive force of the FC stack 4 is considered to be a constant, so when increasing the FC output iv to the output upper limit value _P1 , the FC current value i is i ₂ = P ₂ / It is raised to v. In FIG. 4, the FC calorific value i ₂ (v ₀ −v) in this case is shown as H ₂ . Therefore, the relationship of the following formula (2) holds between P ₂ and H ₂ .

Comparing the first warm-up operation and the second warm-up operation, the electric power consumed by each part of the vehicle 100 except for the battery 108 during the warm-up operation is lower in the first warm-up operation than that of the brake register 6. Power consumption (BR power consumption) P is larger than the second warm-up operation by the amount of _BR . As a result, the relationship expressed by the following equation (3) holds between the output upper limit value P ₁ and the output upper limit value P ₂ .

Also, the time t1 required to raise the temperature of the cooling water by ΔT°C when performing the first warm-up operation, and the time _t1 required to raise the temperature of the cooling water by ΔT°C when performing the second warm-up operation. t ₂ is as shown in the following formulas (4) and (5), respectively.

Here, C ₁ is the cooling circuit 10 when cooling water circulates through the first flow path 11 , the third flow path 13 , the fourth flow path 14 , and the fifth flow path 15 in the cooling circuit 10 . The heat capacity is C ₁ +C ₂ indicates that cooling water is circulated through the first flow path 11, the second flow path 12, the third flow path 13, the fourth flow path 14, and the fifth flow path 15 in the cooling circuit 10. This is the heat capacity of the cooling circuit 10 when

From the above, in order to make the warm-up time of the first warm-up operation shorter than the warm-up time of the second warm-up operation (for t ₁ < t ₂ ), the BR power consumption P _BR must be calculated using the following formula (6). need to be met. Note that since the BR power consumption P _BR is approximately the same value as the BR heat generation amount H _BR , in the formula below, H _BR =P _BR .

(Regarding frost heaving restrictions for FC stack 4)
In the FC stack 4, as the FC current value i increases, more hydrogen and oxygen are consumed and more water is generated. Therefore, in order to suppress the frost heaving phenomenon between the fuel cells, the current upper limit value i _max of the FC stack 4 is set based on the frost heave constraint. The current upper limit value i _max is set only when the first warm-up operation is performed. This is because the FC current value i can become relatively large when the first warm-up operation is performed.

In order to prevent the FC current value i from exceeding the current upper limit value i _max when the first warm-up operation is executed, the BR power consumption _PBR needs to satisfy the following formula (7). .

(Process executed by ECU8)
Below, a process for determining which warm-up operation to select from the first warm-up operation and the second warm-up operation, which is executed by the ECU 8, will be described.

As shown in FIG. 5, in S2, the ECU 8 determines whether the temperature of the cooling water is below a predetermined temperature threshold k. If the temperature of the cooling water is below the temperature threshold value k (in the case of YES), the process proceeds to S4.

In S4, the ECU 8 selects the first warm-up operation. After S4, the process proceeds to S6.

In S6, the ECU 8 obtains the current upper limit value i _max of the FC stack 4 based on the frost heave constraint. Since it is considered that the lower the outside air temperature is, the easier water will freeze, the current upper limit value i _max is set to a larger value as the outside air temperature is higher, and to a smaller value as the outside air temperature is lower. After S6, the process proceeds to S8.

In S8, the ECU 8 determines the value of the BR power consumption _PBR so that the BR power consumption _PBR satisfies the above-mentioned equations (6) and (7). Specifically, the ECU 8 determines the BR power consumption _PBR to be as large as possible within a range that satisfies equations (6) and (7). After S8, the process proceeds to S12.

If it is determined in S2 that the temperature of the cooling water is equal to or higher than the temperature threshold value k (in the case of NO), the process proceeds to S10. In S10, the ECU 8 selects the second warm-up operation. After S10, the process advances to S12.

In S12, the ECU 8 executes the warm-up operation selected in S4 or S10. After S12, the process of FIG. 5 ends.

In this embodiment, the FC stack 4 corresponds to a "fuel cell," the brake register 6 corresponds to a "power consumption unit," the first pump 22 and the second pump 28 correspond to a "circulation control device," and the ECU 8 corresponds to the "control unit".

(Modified example)
In the embodiments described above, the FC system 2 is not limited to the vehicle 100, and may be installed in other mobility devices or stationary devices.

In the above embodiment, a fuel other than hydrogen (for example, ammonia or alcohol) may be used as the fuel for the FC stack 4.

In the above embodiment, a device other than the brake resistor 6 (for example, an electric heating device dedicated to warm-up operation) may be employed as the power consumption unit.

In the above embodiment, a solenoid valve may be provided in the bypass flow path 11a. When performing warm-up operation, the ECU 8 may be configured to close a solenoid valve to prohibit the cooling water from flowing into the bypass passage 11a.

In the above embodiment, the FC system 2 may include devices other than the first pump 22 and the second pump 28 as circulation control devices. For example, the FC system 2 includes a pump provided in the third flow path 13 as a circulation control device, and a pump provided at the downstream end of the third flow path 13 to connect the third flow path 13 to the first flow path 11. A three-way valve that can be switched between this state and a state in which the third flow path 13 is connected to the second flow path 12 may be provided. Even in this case, both the first warm-up operation and the second warm-up operation described above can be performed.

In the above embodiment, a configuration was described in which the BR power consumption _PBR in the first warm-up operation satisfies equations (6) and (7). In another embodiment, the BR power consumption P _BR in the first warm-up operation may not satisfy at least one of the above-mentioned equations (6) and (7). For example, in the above embodiment, the ECU 8 may be configured to execute S12 after S6 in FIG. 5 without executing S8.

2: FC system 4: FC stack 6: Brake register 8: ECU
10: Cooling circuit 11: First flow path 11a: Bypass flow path 12: Second flow path 13: Third flow path 14: Fourth flow path 15: Fifth flow path 16: Sixth flow path 22: First pump 24: First check valve 26: Intercooler 28: Second pump 30: Second check valve 32: Three-way valve 34: Ion exchanger 36: Radiator 100: Vehicle 102: Pair of front wheels 104: Pair of rear wheels 106 : Traveling motor 108 : Battery

Claims (6)

A fuel cell system,
a cooling circuit comprising a first flow path and a second flow path connected in parallel to each other;
a fuel cell provided in the first flow path;
a power consumption unit provided in the second flow path and capable of consuming power generated by the fuel cell;
at least one circulation control device that is provided in the cooling circuit and controls a circulation path of cooling water;
A control unit capable of executing a first warm-up operation by controlling the operation of the fuel cell, the power consumption unit, and the at least one circulation control device,
In the first warm-up operation, the cooling water circulates in both the first flow path and the second flow path, the fuel cell generates power, and a part of the power generated by the fuel cell is transferred to the electric power. consumed in consumption units,
fuel cell system. The control unit is further capable of performing a second warm-up operation,
In the second warm-up operation, the cooling water circulates in the first flow path, the cooling water does not circulate in the second flow path, and the fuel cell generates power, and the power generated by the fuel cell 2. The fuel cell system of claim 1, wherein: is not consumed in the power consuming unit. The control unit detects the temperature of the cooling water when the fuel cell system is started, and executes the first warm-up operation when the detected temperature is lower than a predetermined temperature, and the control unit detects the temperature of the cooling water when the detected temperature is lower than a predetermined temperature. The fuel cell system according to claim 2, wherein the second warm-up operation is performed when the temperature exceeds a predetermined temperature. The theoretical value of the electromotive force of the fuel cell is _v0 , the measured value of the electromotive force of the fuel cell is v, the cooling water circulates in the first flow path and the cooling water does not circulate in the second flow path. The heat capacity of the cooling circuit at the time is C ₁ , the heat capacity of the cooling circuit when the cooling water circulates in both the first flow path and the second flow path is C _{1 +C 2 , and the heat capacity of the cooling circuit during the second warm-up operation is C 1} +C ₂ . When the output upper limit of the fuel cell is _P2 ,
The power consumption _PBR of the power consumption unit in the first warm-up operation is calculated by the following formula:

The fuel cell system according to claim 2, which satisfies the following. When the actual value of the electromotive force of the fuel cell is v, the output upper limit value of the fuel cell in the second warm-up operation is P ₂ , and the upper limit current value of the fuel cell based on the frost heaving constraint is i _max ,
The power consumption _PBR of the power consumption unit in the first warm-up operation is calculated by the following formula:

The fuel cell system according to claim 2, which satisfies the following. The fuel cell system is mounted on a vehicle equipped with a travel motor that drives wheels,
2. The fuel cell system according to claim 1, wherein the power consumption unit is a brake register that consumes power generated when the travel motor dynamically brakes the wheels.

Images