JP7400749B2 - fuel cell system - Google Patents

Description

The technology disclosed herein relates to a fuel cell system. In particular, the present invention relates to a fuel cell system having a plurality of fuel cell modules and one refrigerant cooling device.

The fuel cell systems of Patent Documents 1 and 2 include a plurality of fuel cell modules, and can output large amounts of electric power by adding up the outputs of the plurality of fuel cell modules. The fuel cell systems of Patent Documents 1 and 2 use one refrigerant cooling device to cool the fuel cell bodies of a plurality of fuel cell modules. A typical refrigerant cooling device is a radiator. The plurality of fuel cell modules and one refrigerant cooling device are connected by refrigerant pipes. The refrigerant pipe distributes refrigerant cooled by the refrigerant cooling device to a plurality of fuel cell modules (fuel cell main bodies).

The fuel cell system disclosed in Patent Document 1 uses one pump to send refrigerant to a plurality of fuel cell modules. In the fuel cell system of Patent Document 2, each fuel cell module is equipped with a pump and a valve. The pump supplies refrigerant to the fuel cell main body of its own fuel cell module. The valve regulates the flow rate of refrigerant passing through the fuel cell body of its own fuel cell module. Both the pump and the valve are regulators that adjust the flow rate of refrigerant passing through the fuel cell body. Hereinafter, the pump and valve that adjust the flow rate of the refrigerant passing through the fuel cell body may be simply referred to collectively as a regulator.

In the fuel cell system of Patent Document 2, the controller (local controller) of each fuel cell module sends the temperature of the fuel cell main body (fuel cell temperature) to a higher-level controller. The host controller sends the maximum value or average value of the plurality of fuel cell temperatures to each local controller as a reference value for regulator control. Each local controller controls the regulator based on reference values sent from the higher-level controller to maintain the fuel cell temperature within an appropriate temperature range.

In the fuel cell system of Patent Document 1, one pump distributes refrigerant to a plurality of fuel cell modules, and therefore the flow rate of refrigerant sent to each fuel cell module cannot be adjusted individually. On the other hand, in the fuel cell system of Patent Document 2, each fuel cell module is equipped with a regulator, so the flow rate of the refrigerant can be adjusted individually. On the other hand, if each of the plurality of fuel cell modules individually controls the regulator, the difference in the flow rate of the refrigerant among the plurality of fuel cell modules becomes large, and a backflow of the refrigerant may occur in the fuel cell module with a small flow rate. In the fuel cell module of Patent Document 2, since the regulators of the plurality of fuel cell modules are controlled based on the same reference value, variations in the operating amounts of the regulators are reduced. Therefore, the difference in coolant flow rate between the plurality of fuel cell modules becomes small. Note that in the fuel cell system of Patent Document 2, each local controller has a map that defines the relationship between the reference value and the control command value to the regulator. A plurality of fuel cell modules have different maps, and even if they are based on the same reference value, the control command value to the regulator (the operating amount of the regulator) may be different for each fuel cell module.

Japanese Patent Application Publication No. 09-259909 US Patent Publication No. 2020/0171976

When employing the technology disclosed in Patent Document 2, a host controller is required in addition to the local controllers of the plurality of fuel cell modules. One aspect of the technology disclosed in this specification provides a technology for reducing variations in command values for regulators of multiple fuel cell modules (that is, variations in coolant flow rate) without requiring a host controller. On the other hand, if the regulators of a plurality of fuel cell modules are controlled with the same command value, it becomes impossible to perform temperature control according to the temperature of each individual fuel cell. Another aspect of the technology disclosed in this specification is to reduce the temperature of each fuel cell main body while suppressing excessive variations in command values to regulators of multiple fuel cell modules (i.e., variations in flow rate). The present invention provides technology that enables adjustment of refrigerant flow rate according to

One embodiment of the fuel cell system disclosed in this specification includes a refrigerant cooling device, a plurality of fuel cell modules, and refrigerant pipes. Each fuel cell module includes a fuel cell main body and a local controller. The refrigerant cooling device cools the refrigerant. The refrigerant pipes connect the refrigerant cooling device and the plurality of fuel cell main bodies, and distribute the refrigerant from the refrigerant cooling device to the plurality of fuel cell main bodies. Each fuel cell module includes a regulator that adjusts the flow rate of refrigerant passing through its own fuel cell body. Each local controller determines the command value (own command value) for the regulator of its own fuel cell module, and also corrects the own command value by referring to the command value (other command value) determined by other local controllers. , the regulator is controlled based on the corrected own command value (corrected command value). In the fuel cell system disclosed in this specification, the local controller of each fuel cell module controls its own fuel cell by referring to command values (other command values) determined by other local controllers without requiring a higher-level controller. Determine the command value (corrected command value) for the regulator of the module. Therefore, variations in command values for the regulators of the plurality of fuel cell modules are reduced. As a result, variations in the flow rate of the refrigerant flowing through the plurality of fuel cell bodies are reduced, and backflow does not occur.

In another aspect of the fuel cell system disclosed in this specification, each local controller determines an allowable command range based on its own command value and other command values, and when its own command value is within the allowable command range. The command value is determined as the corrected command value. If the own command value is outside the allowable command range, each local controller determines a value within the allowable command range and closest to the own command value as the corrected command value. The allowable command range is selected such that backflow does not occur even if the local controllers of multiple fuel cell modules drive the regulators with different values within the allowable command range. Since each local controller determines the final command value (corrected command value) to the regulator from the same allowable command range, the maximum variation in command values is the difference between the upper and lower limits of the allowable command range. This fuel cell system can adjust the flow rate of refrigerant according to the temperature of each fuel cell body while suppressing variations in command values for the regulator.

Details and further improvements of the technology disclosed in this specification will be explained in the following "Detailed Description of the Invention".

FIG. 1 is a block diagram of a fuel cell system according to an embodiment. 5 is a flowchart of regulator control executed by each local controller. It is a flowchart of the 1st modification of regulator control. It is a flowchart of the 2nd modification of regulator control.

A fuel cell system 2 according to an embodiment will be described with reference to the drawings. FIG. 1 shows a block diagram of the fuel cell system 2. As shown in FIG. The fuel cell system 2 is mounted on an electric vehicle. The fuel cell system 2 supplies the generated electric power to a running motor (not shown).

The fuel cell system 2 includes a plurality of fuel cell modules 10a to 10c, a radiator 20, and a refrigerant pipe 30. The fuel cell system 2 may be a system including only two fuel cell modules, or may be a system including four or more fuel cell modules.

The fuel cell module 10a includes a fuel cell main body 11a, a refrigerant supply pump 12a, a flow rate adjustment valve 13a, a local controller 14a, and a temperature sensor 16a. The fuel cell module 10b (10c), like the fuel cell module 10a, includes a fuel cell main body 11b (11c), a refrigerant supply pump 12b (12c), a flow rate adjustment valve 13b (13c), a local controller 14b (14c), and a temperature sensor. 16b (16c). In addition to the parts shown in FIG. 1, the fuel cell system 2 includes devices such as a hydrogen tank and a gas-liquid separator, but these are not shown. Each of the fuel cell modules 10a-10c has devices not shown in FIG. 1, such as a hydrogen injector.

The fuel cell bodies 11a to 11c are a fuel cell stack and generate electricity from hydrogen and oxygen. The power output from the fuel cell bodies 11a to 11c is sent to a power converter (not shown) through a power line 41. The power converter converts the total power output by the fuel cell bodies 11a to 11c into driving power for a motor for driving, and supplies the driving power to the motor. The fuel cell system 2 connects a plurality of fuel cell main bodies 11a to 11c in parallel and can obtain large electric power.

The fuel cell bodies 11a to 11c and the radiator 20 are connected by a refrigerant pipe 30. The radiator 20 releases heat from the refrigerant and lowers the temperature of the refrigerant. That is, the radiator 20 corresponds to a refrigerant cooling device that cools refrigerant. The thick arrow line in FIG. 1 indicates the direction of flow of the refrigerant. The refrigerant pipe 30 distributes the refrigerant cooled by the radiator 20 to the fuel cell bodies 11a to 11c of the plurality of fuel cell modules 10a to 10c. The refrigerant pipe 30 returns the refrigerant that has absorbed the heat of the fuel cell bodies 11a to 11c to the radiator 20. The refrigerant that has absorbed the heat of the fuel cell bodies 11a to 11c is cooled by the radiator 20, and sent through the refrigerant pipe 30 to the fuel cell bodies 11a to 11c again. One radiator 20 (refrigerant cooling device) cools the fuel cell bodies 11a to 11c of the plurality of fuel cell modules 10a to 10c via a refrigerant.

The local controller 14a of the fuel cell module 10a controls the fuel cell main body 11a, and also controls the refrigerant supply pump 12a and the flow rate adjustment valve 13a based on the measurement data of the temperature sensor 16a. The temperature sensor 16a is arranged in the refrigerant pipe 30 on the refrigerant downstream side of the fuel cell main body 11a. The temperature sensor 16a measures the temperature of the refrigerant that has passed through the fuel cell main body 11a. The temperature of the refrigerant obtained from the temperature sensor 16a corresponds to an approximate value of the temperature of the fuel cell main body 11a. Measurement data from the temperature sensor 16a is sent to the local controller 14a.

Both the refrigerant supply pump 12a and the flow rate adjustment valve 13a adjust the flow rate of the refrigerant passing through the fuel cell main body 11a. By controlling the flow rate of the refrigerant passing through the fuel cell main body 11a, the temperature of the refrigerant, that is, the temperature of the fuel cell main body 11a can be adjusted. The local controller 14a controls the refrigerant supply pump 12a and the flow rate adjustment valve 13a based on the temperature of the refrigerant passing through the fuel cell main body 11a, and maintains the temperature of the fuel cell main body 11a within an appropriate temperature range.

Fuel cell module 10b (10c) has the same structure as fuel cell module 10a. The local controller 14b (14c) acquires the temperature of the refrigerant passing through the fuel cell main body 11b (11c) from the temperature sensor 16b (16c), and controls the refrigerant supply pump 12b (12c) and flow rate adjustment valve 13b (13c) based on the temperature. ) to maintain the temperature of the fuel cell body 11b (11c) within an appropriate temperature range.

Hereinafter, for convenience of explanation, the plurality of fuel cell modules 10a to 10c will be collectively referred to as the fuel cell module 10, and the plurality of fuel cell bodies 11a to 11c will be collectively referred to as the fuel cell body 11. The plurality of local controllers 14a to 14c, the plurality of refrigerant supply pumps 12a to 12c, and the plurality of flow rate adjustment valves 13a to 13c may also be collectively referred to as the local controller 14, refrigerant supply pump 12, and flow rate adjustment valve 13, respectively. . In addition, since both the refrigerant supply pump 12 and the flow rate adjustment valve 13 are regulators that adjust the flow rate of the refrigerant passing through the fuel cell main body 11, the refrigerant supply pump 12 and the flow rate adjustment valve 13 will be referred to as "adjustment" below. Sometimes referred to collectively as "vessel".

The plurality of local controllers 14 are communicably connected via a network 40 and can exchange data with each other.

The plurality of fuel cell modules 10 (the plurality of fuel cell main bodies 11) are supplied with refrigerant from one radiator 20 through a refrigerant pipe 30. The refrigerant pipe 30 branches into a plurality of fuel cell bodies 11 . When the fuel cell modules 10 drive regulators (refrigerant supply pump 12 or flow rate adjustment valve 13) independently of each other, the operations of the multiple regulators (the output of the refrigerant supply pump 12 or the opening degree of the flow rate adjustment valve) are largely different. There may be cases where this occurs. If the operation of the regulators is significantly different, there is a risk that the refrigerant will flow back in the fuel cell module 10 that has the refrigerant supply pump 12 with a small output (or the flow rate adjustment valve 13 with a small opening). The backflow of the refrigerant may damage the fuel cell module 10, so it is desirable to prevent it. In the fuel cell system 2, a plurality of local controllers 14 cooperate to suppress variations in the operation of the regulator (variations in flow rate).

FIG. 2 shows a flowchart of regulator control executed by each local controller 14. The processing executed by each local controller 14 will be described with reference to FIG. 2. In the following, regulator control will be explained focusing on the local controller 14a of the fuel cell module 10a.

The local controller 14a receives the measured value of the temperature sensor 16a, and obtains the temperature of the refrigerant passing through the fuel cell main body 11a (step S11). The local controller 14a determines a command value for the regulator (refrigerant supply pump 12a or flow rate adjustment valve 13a) of its own fuel cell module 10a based on the obtained refrigerant temperature (step S12). The relationship between temperature and command value is stored in the local controller 14 in advance. The relationship between temperature and command value is given by a map or a relational expression. Generally, the higher the temperature, the larger the command value is set.

When the regulator is the refrigerant supply pump 12a, the command value is expressed by the target rotation speed of the refrigerant supply pump 12a. The higher the temperature of the refrigerant, the higher the command value, that is, the target rotation speed of the refrigerant supply pump 12a. The higher the rotation speed of the refrigerant supply pump 12a, the lower the temperature of the refrigerant passing through the fuel cell main body 11a. When the regulator is the flow rate adjustment valve 13a, the command value is expressed by the opening degree of the flow rate adjustment valve 13a. The higher the temperature of the refrigerant, the larger the command value, that is, the opening degree of the flow rate adjustment valve 13a. The larger the opening degree of the flow rate adjustment valve 13a, the lower the temperature of the refrigerant passing through the fuel cell main body 11a. The command value may be a combination of the target rotation speed of the refrigerant supply pump 12a and the opening degree of the flow rate adjustment valve 13a.

The other local controllers 14b, 14c also each determine command values for the regulators under their control.

For convenience of explanation, the command value determined by the local controller 14a of interest will be referred to as the own command value, and the command values determined by the other local controllers 14b and 14c will be referred to as other command values.

The local controller 14a transmits its own command value to the other local controllers 14b and 14c via the network 40 (step S13). The other local controllers 14b and 14c also transmit command values for their own regulators (other command values for the local controller 14a) to the local controller 14a. The local controller 14a receives other command values from the other local controllers 14b and 14c (step S14).

The local controller 14a acquires the command values determined by all the local controllers 14 (that is, its own command value and all other command values). The local controller 14a corrects the own command value based on the own command value and other command values (step S15). The self-command value after correction is referred to as a corrected command value.

An example of correction of the own command value will be explained. The local controller 14a determines the average value of its own command value and all other command values as the corrected command value. Alternatively, the local controller 14a determines the maximum value of the own command value and all other command values as the corrected command value. Finally, the local controller 14a controls the regulator based on the correction command value (step S16).

The local controller 14a repeats the process shown in FIG. 2 at regular intervals. Local controllers 14b and 14c also perform similar processing.

When all the local controllers 14 perform the same correction calculation, all the local controllers 14 obtain the same correction command value. That is, in all fuel cell modules 10, the final command value (correction command value) to the regulator becomes the same. Variations in the operation of regulators among the plurality of fuel cell modules 10 are reduced. In the fuel cell system 2 of the embodiment, the regulators operate in the same way in all the fuel cell modules 10, so the coolant flows equally into all the fuel cell bodies 11. Refrigerant does not flow backward in any of the fuel cell bodies 11.

In the fuel cell system 2, each local controller 14 sends its own command value to other local controllers 14. There is no need for a higher-level controller that manages the plurality of local controllers 14 and receives its own command value from each local controller 14 and generates a correction command value.

In the fuel cell system 2 of the embodiment, all local controllers 14 obtain the same correction command value. That is, the regulators (refrigerant supply pumps 12 or flow rate adjustment valves 13) of all fuel cell modules 10 perform the same operation. Therefore, it is difficult to precisely control the regulator according to the temperature of each fuel cell main body 11. In the modification described below, it is possible to control the regulator according to the temperature of each fuel cell main body 11 while suppressing excessive variations in the flow rate flowing into the fuel cell main bodies 11 of a plurality of fuel cell modules 10. can do. A first variant of regulator control is shown with reference to FIG.

Steps S21 to S24 in the flowchart in FIG. 3 are the same as steps S11 to S14 in the flowchart in FIG. 2, so a description thereof will be omitted.

The local controller 14a, which has received the other command values from the other local controllers 14b and 14c, determines an allowable command range based on the own command value and the other command values (step S25). The allowable command range is a predetermined range that includes the average value of the own command value and other command values. The allowable command range is selected so that no backflow occurs even if the regulator is controlled by different command values selected by a plurality of local controllers 14 within the range. The allowable command range is stored in each local controller 14 as a function of the average value of the own command value and other command values.

The local controller 14a compares the determined allowable command range with its own command value (step S26). If the own command value is within the allowable range (step S26: YES), the local controller 14a determines the own command value as the corrected command value (step S27). On the other hand, if the self-command value is outside the allowable range (step S26: NO), the local controller 14a determines the value within the permissible command range that is closest to the self-command value as the corrected command value (step S28). ). More specifically, when the own command value is smaller than the lower limit value of the allowable command range, the local controller 14a determines the lower limit value as the corrected command value. If the own command value is larger than the upper limit of the allowable command range, the local controller 14a determines the upper limit as the corrected command value.

Finally, the local controller 14a controls the regulator using the determined correction command value (step S19). Local controllers 14b and 14c also perform similar processing.

According to the control of the first modification, the command values of the plurality of local controllers 14 fall within the allowable command range. Therefore, the difference in the flow rate of the refrigerant is suppressed within a predetermined range, and no backflow of the refrigerant occurs. Further, when the own command value is high, the corrected command value becomes the upper limit of the allowable command range, and when the own command value is low, the corrected command value becomes the lower limit of the allowable command range. If the self-command value is within the allowable range, the self-command value becomes the correction command value. The corrected command value can vary within the allowable command range depending on the magnitude of the own command value. According to the regulator control of the first modification, it is possible to control the regulators according to the temperature of each fuel cell main body 11 while suppressing excessive variations in the operation of the regulators of the plurality of fuel cell modules 10. It can be realized.

FIG. 4 shows a second modification of regulator control. In this modification, the temperature measured by the temperature sensor 16 (the temperature of the refrigerant that has passed through the fuel cell main body 11) is adopted as the self-command value.

The local controller 14a acquires the temperature from the temperature sensor 16a (step S31). The local controller 14a transmits the acquired temperature as a self-command value to the other local controllers 14b and 14c (step S32). Other local controllers 14b (14c) also transmit the measurement data of the temperature sensor 16b (16c) included in its own fuel cell module 10b (10c) to other local controllers as its own command value (another command value for the local controller 14a). Send. That is, the local controller 14a receives the temperature (other command value) from the other local controllers 14b and 14c (step S33).

The local controller 14a determines an allowable command range based on the own command value and other command values (step S34). As in the case of FIG. 2, the allowable command range is a predetermined range that includes the average value of the own command value and other command values, and is stored in advance in each local controller 14 as a function of the average value.

The local controller 14a compares the determined allowable command range with its own command value (step S35). If the own command value is within the allowable range (step S35: YES), the local controller 14a determines the own command value as the corrected command value (step S36). On the other hand, if the self-command value is outside the permissible range (step S35: NO), the local controller 14a determines the value within the permissible command range that is closest to the self-command value as the corrected command value (step S37). ). More specifically, when the own command value is smaller than the lower limit value of the allowable command range, the local controller 14a determines the lower limit value as the corrected command value. If the own command value is larger than the upper limit of the allowable command range, the local controller 14a determines the upper limit as the corrected command value.

The correction command value is also expressed in temperature. The relationship between temperature and regulator command value (final command value) is stored in advance in the local controller 14a. The local controller 14a converts the correction command value into a final command value using the stored relationship (step S38). When the regulator is the refrigerant supply pump 12a, the final command value is expressed by the target rotation speed. When the regulator is the flow rate adjustment valve 13a, the final command value is expressed by the target opening degree of the valve. Finally, the local controller 14a controls the regulator using the obtained final command value (step S39). The local controller 14a repeats the process of FIG. 4 at a predetermined period. Local controllers 14b and 14c also perform similar processing.

Similarly to the case of the first modification, the control of the second modification also suppresses the variation in the operation of the regulators of the plurality of fuel cell modules 10 (that is, the variation in flow rate) from becoming excessive. Control of the regulator according to the temperature of the battery body 11 can be realized.

Points to note regarding the techniques described in the examples will be described. The number of fuel cell modules that the fuel cell system has may be two or more. The refrigerant cooling device is not limited to the radiator 20, and may be any device that can cool the refrigerant. The fuel cell system may include multiple refrigerant cooling devices. The technology disclosed herein can be applied to a system that distributes coolant to multiple fuel cell modules.

Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims as filed. Furthermore, the techniques illustrated in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of the objectives has technical utility in itself.

2: Fuel cell system 10, 10a to 10c: Fuel cell module 11, 11a to 11c: Fuel cell main body 12, 12a to 12c: Refrigerant supply pump 13, 13a to 13c: Flow rate adjustment valve 14, 14a to 14c: Local controller 16 , 16a to 16c: Temperature sensor 20: Radiator 30: Refrigerant pipe 40: Network 41: Power line

Claims (5)

a refrigerant cooling device that cools the refrigerant;
multiple fuel cell modules each including a fuel cell main body and a local controller;
a refrigerant pipe connecting the refrigerant cooling device and the plurality of fuel cell main bodies, and distributing the refrigerant from the refrigerant cooling device to the plurality of fuel cell main bodies;
It is equipped with
Each of the fuel cell modules is equipped with a regulator that adjusts the flow rate of the refrigerant passing through its own fuel cell main body,
Each of the local controllers determines a command value (own command value) for the regulator of its own fuel cell module, and also refers to the command value (other command value) determined by the other local controller. A fuel cell system that corrects a self-command value and controls the regulator based on the corrected self-command value (corrected command value). 2. The fuel cell system according to claim 1, wherein each of the local controllers determines the maximum value of the own command value and the other command value as the correction command value. 2. The fuel cell system according to claim 1, wherein each of the local controllers determines an average value of the own command value and the other command value as the correction command value. Each of the local controllers determines an allowable command range based on the own command value and the other command value, and when the own command value is within the permissible command range, determines the own command value as the corrected command value. According to claim 1, when the self-command value is outside the permissible command range, a value within the permissible command range and closest to the self-command value is determined as the corrected command value. The fuel cell system described. 5. The regulator is at least one of a pump that supplies the refrigerant to the fuel cell main body, and a valve that adjusts the flow rate of the refrigerant passing through the fuel cell main body. fuel cell system.

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