JP2007226986A - Fuel cell system and method of controlling fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the next starting of a fuel cell without giving sense of discomfort to an operator when the fuel cell is stopped. <P>SOLUTION: A system includes a fuel cell 1 generating electric power by the reaction of reaction gases; a drop-to-freezing-point prediction means predicting whether at least a part of the fuel cell 1 drops to a freezing point or lower or not during stop of the fuel cell 1; a drop-to-freezing-pint notifying means notifying the prediction to an operation control person of the fuel cell when drop to the freezing point or lower is predicted with the drop-to-freezing-point prediction means; and an under-freezing-point corresponding means conducting under-freezing-point corresponding operation to the fuel cell 1 before the fuel cell 1 drops to the freezing point or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system and a fuel cell management method.

  In general, in the case of a fuel cell, if there is a possibility of freezing in order to prevent water from freezing in the fuel cell during the stoppage period in a low temperature environment and reducing the power generation performance at the next power generation, A scavenging gas is circulated through the reaction gas flow passages in the fuel cell to scavenge, and water remaining in these gas flow passages is discharged.

For example, in Patent Document 1, when there is a possibility of freezing due to the lowest temperature within 24 hours estimated based on the outside air temperature detected by the outside air temperature sensor when the fuel cell is stopped, the fuel cell stack or the air discharge A technique is described in which an atomizer attached to a system or the like is operated to atomize water remaining inside the fuel cell stack, and air is circulated through the reaction gas flow passage to scavenge.
Japanese Patent Laying-Open No. 2005-251576

However, even if the fuel cell is stopped, if an auxiliary machine such as a compressor is continuously operated for scavenging when the fuel cell is stopped, the operator feels uncomfortable.
Accordingly, the present invention provides a fuel cell system and a fuel cell management method capable of ensuring the next startability of the fuel cell without causing the operator to feel uncomfortable when the fuel cell is stopped.

In the fuel cell system and the fuel cell management method according to the present invention, the following means are adopted in order to solve the above problems.
The invention according to claim 1 is a fuel cell that generates power by reaction of a reaction gas (for example, a fuel cell 1 in an embodiment described later), and at least a part of the fuel cell is below freezing point while the fuel cell is stopped. Sub-freezing prediction means (eg, steps S101, S107, S108, S109, S200, and S300 in the embodiments described later) for predicting whether or not the fuel is predicted to be below freezing by the sub-freezing prediction means. A freezing point notifying means for notifying the battery operation manager (for example, S102 in the embodiment described later) and a freezing point corresponding operating means for performing a predetermined freezing point corresponding operation to the fuel cell before the fuel cell becomes below freezing point ( For example, the fuel cell system includes steps S104 and S105) in an embodiment described later.
By configuring in this way, the operation manager is notified that the temperature will be below freezing, and the freezing operation is performed, so that the next startability of the fuel cell can be secured and The uncomfortable feeling at the time of starting can be reduced. Also, sub-freezing operation is possible even when the operation manager is not near the fuel cell. In the present invention, “when the fuel cell is stopped” includes “when the fuel cell is stopped”.

According to a second aspect of the present invention, in the first aspect of the invention, the below-freezing-point corresponding operation means is capable of a plurality of below-freezing-point corresponding operation, and one of the plurality of below-freezing-point corresponding operations is instructed. Means (for example, step S103 in the embodiment described later), and the below-freezing corresponding operation means performs a below-freezing corresponding operation in accordance with an instruction from the corresponding operation instruction means.
By configuring in this way, it is possible to perform a sub-freezing operation in accordance with an instruction from the operation manager, so that it is possible to further reduce the sense of discomfort when the fuel cell is started next time for the operation manager.

According to a third aspect of the present invention, in the first or second aspect of the invention, the below-freezing-compatible operation includes a warm-up operation by restarting the fuel cell and a reaction gas flow path (for example, described later) of the fuel cell. In this embodiment, the fuel gas flow passage 5 and the oxidant gas flow passage 6) are at least one of the scavenging operations for scavenging.
By performing the warm-up operation, the fuel cell does not drop below the freezing point, and the factor that deteriorates the startability of the fuel cell can be removed, so that the next startability can be ensured.
By performing the scavenging operation, moisture in the fuel cell can be removed before the temperature becomes below freezing point, so that the next startability is slightly lowered, but it is possible to avoid a situation where the start cannot be started.

According to a fourth aspect of the present invention, when it is predicted that at least a part of the fuel cell (for example, the fuel cell 1 in an embodiment described later) is below freezing point while the fuel cell is stopped, the prediction of the fuel cell is performed. A fuel cell management method comprising: notifying an operation manager and performing a predetermined sub-freezing operation on the fuel cell before the fuel cell is below freezing.
By configuring in this way, the operation manager is notified that the temperature will be below freezing, and the freezing operation is performed, so that the next startability of the fuel cell can be secured and The uncomfortable feeling at the time of starting can be reduced. In the present invention, “when the fuel cell is stopped” includes “when the fuel cell is stopped”.

According to the invention which concerns on Claim 1, while being able to ensure the next startability of a fuel cell, the discomfort at the time of starting next with respect to a driving | operation manager can be reduced.
According to the invention which concerns on Claim 2, the discomfort at the time of starting a fuel cell next time with respect to a driving | operation manager can further be reduced.
According to the invention of claim 3, the next startability can be secured by performing the warm-up operation, and the scavenging operation is performed to avoid the situation where the fuel cell cannot be started at the next start-up. be able to.
According to the invention which concerns on Claim 4, while being able to ensure the next startability of a fuel cell, the discomfort at the time of starting next with respect to a driving | operation manager can be reduced.

Embodiments of a fuel cell system and a fuel cell management method according to the present invention will be described below with reference to the drawings of FIGS. Note that the fuel cell system in this embodiment is an embodiment mounted on a fuel cell vehicle.
First, a schematic configuration of a fuel cell system according to the present invention will be described with reference to FIG.
The fuel cell 1 is of a type that obtains electric power by chemically reacting a reaction gas. For example, a plurality of cells formed by sandwiching a solid polymer electrolyte membrane made of a solid polymer ion exchange membrane or the like between an anode and a cathode from both sides. The fuel gas flow passage (reaction gas flow passage) 5 on the anode side is supplied with hydrogen gas as fuel gas, and the oxidant gas flow passage (reaction gas flow passage) 6 on the cathode side is supplied with oxidant. When air containing oxygen is supplied as a gas, hydrogen ions generated by a catalytic reaction at the anode move through the solid polymer electrolyte membrane to the cathode, and cause an electrochemical reaction with oxygen at the cathode to generate electricity, Is generated. Part of the generated water generated on the cathode side permeates the solid polymer electrolyte membrane and back diffuses to the anode side, so that the generated water also exists on the anode side.

  The air is pressurized to a predetermined pressure by a compressor 7 such as a supercharger and supplied to the oxidant gas flow passage 6 of the fuel cell 1 through the air supply passage 8. After the air supplied to the fuel cell 1 is used for power generation, it is discharged from the fuel cell 1 together with the generated water on the cathode side to the air discharge passage 9 and is discharged to the exhaust treatment device (not shown) via the pressure control valve 10. The

On the other hand, the hydrogen gas supplied from the hydrogen tank 15 flows through the hydrogen gas supply flow path 17 and the shutoff valve 20, is reduced to a predetermined pressure by the regulator 16, passes through the ejector 19, and enters the fuel gas flow path 5 of the fuel cell 1. Supplied. The unreacted hydrogen gas that has not been consumed is discharged from the fuel cell 1 as an anode off-gas, sucked into the ejector 19 through the anode off-gas flow path 18, and joined with fresh hydrogen gas supplied from the hydrogen tank 15. Then, it is supplied again to the fuel gas flow passage 5 of the fuel cell 1. That is, the anode off gas discharged from the fuel cell 1 circulates in the fuel cell 1 through the anode off gas passage 18 and the hydrogen gas supply passage 17 downstream of the ejector 19.
The air supply flow path 8 and the hydrogen gas supply flow path 17 downstream from the ejector 19 are connected by a scavenging flow path 24 having a scavenging valve 25.

The anode off-gas flow path 18 is provided with a temperature sensor 23 that detects the temperature of the anode off-gas discharged from the fuel cell 1. In this embodiment, the anode off-gas temperature detected by the temperature sensor 23 is regarded as the internal temperature (system temperature) of the fuel cell 1.
An anode off-gas discharge channel 22 having a discharge valve 21 branches off from the anode off-gas channel 18. The exhaust valve 21 is opened as necessary to discharge the anode off-gas when the concentration of impurities (water, nitrogen, etc.) in the hydrogen gas circulating through the fuel cell 1 becomes high. The anode off gas discharged from the discharge valve 21 is discharged to the exhaust treatment device, and the anode off gas is diluted with the cathode off gas in the exhaust treatment device.

In this fuel cell system, when the fuel cell 1 is stopped, when the internal temperature of the fuel cell 1 is predicted to be below the freezing point, control is performed so that the operation corresponding to the below freezing point is performed. Note that “when the fuel cell is stopped” includes “when the fuel cell is stopped”. As the freezing operation, warm-up operation and scavenging operation are possible, and the user (fuel cell operation manager) selects which operation to perform.
The warm-up operation is an operation in which a reactive gas (hydrogen gas and air) is supplied to the fuel cell 1 and restarted, and power generation (warm-up power generation) is performed to perform independent warm-up.
In the scavenging operation, the pressure control valve 10, the exhaust valve 21, and the scavenging valve 25 are opened, and the compressor 7 is operated so that air flows as scavenging gas through the fuel gas flow path 5 and the oxidant gas flow path 6 of the fuel cell 1. In this operation, moisture remaining in the gas flow passages 5 and 6 is discharged.

When the user is planning to shorten the stop time of the fuel cell 1, it is preferable to select the warm-up operation. This is because the temperature of the fuel cell 1 does not drop below the freezing point due to the warm-up operation, the factor that deteriorates the startability of the fuel cell can be removed, and the next startability can be ensured.
On the other hand, when the user is planning to extend the stop time of the fuel cell 1, the scavenging operation is preferable. By performing the scavenging operation, the water in the fuel cell 1 can be removed before the temperature becomes below freezing point, so that it is possible to avoid a situation in which the startup cannot be performed, although the next startup performance is slightly reduced. It is.

  By the way, since the user is not necessarily in the vehicle while the fuel cell 1 is stopped, the driving method for the sub-freezing operation can be selected even when the user is not in the vehicle. As shown in FIG. 2, the vehicle V includes a transceiver (not shown) that can communicate with a user's mobile phone 41 and the like via the Internet 40, and the transceiver is connected to the ECU 30 of the fuel cell system. Therefore, the fuel cell system can be controlled in accordance with an instruction from the user.

  A first embodiment of the fuel cell management method will be described with reference to the flowchart shown in FIG. The below-freezing point operation control routine shown in the flowchart of FIG. 3 is executed at regular intervals by the electronic control unit (ECU) 30 with the input of the OFF signal of the ignition switch 31 as a start condition. Further, the temperature detection by the temperature sensor 23 is performed at regular intervals even while the ignition switch 31 is OFF.

In step S101, it is determined whether or not the temperature (system temperature) of the fuel cell 1 detected by the temperature sensor 23 is lower than a predetermined value t1. The predetermined value t1 is set to a temperature slightly higher than 0 ° C. (for example, 7 ° C.). If the determination result in step S101 is “YES” (lower than t1), the fuel cell 1 is stopped while the fuel cell 1 is stopped. Since it is predicted that at least a part of 1 may be below freezing point, the process proceeds to step S102, and (1) the prediction result that the freezing point will be below freezing, and (2) the temperature of the fuel cell 1 detected by the temperature sensor 23. And (3) the remaining fuel (remaining amount) in the hydrogen tank 15 is notified to the user of this vehicle by telephone or e-mail.
The user who has received the notification considers the remaining fuel, selects whether the operation corresponding to the freezing point for the fuel cell 1 is to be the warm-up operation or the scavenging operation, and sends a command to the ECU 30 by telephone or e-mail.

Next, it progresses to step S103 and ECU30 determines whether the instruction | indication from a user is a warm-up driving | operation.
If the determination result in step S103 is “YES”, that is, if there is an instruction for warm-up operation from the user, the process proceeds to step S104 to perform warm-up operation.
On the other hand, when the determination result in step S103 is “NO”, that is, when there is an instruction for the scavenging operation or when there is no instruction from the user, the process proceeds to step S105 and the scavenging operation is performed.
After executing the processing of steps S104 and S105, the user is notified that the countermeasure for the below freezing point has been completed by telephone or e-mail, and the execution of this routine is terminated.
If the determination result in step S101 is “NO” (t1C or more), it is predicted that the fuel cell 1 will not become below freezing while the fuel cell 1 is stopped, and the operation corresponding to below freezing is not required, so this routine is not necessary. The execution of is terminated.

  According to the sub-freezing operation control of the first embodiment, since the sub-freezing operation is performed after notifying the user that the temperature is below freezing, the next startability of the fuel cell can be ensured and A sense of incongruity at the next start-up can be reduced. In particular, the user can select whether to perform the sub-freezing operation by the warm-up operation or the scavenging operation, and the sub-freezing operation can be performed according to the user's judgment, so that the user starts the fuel cell 1 next time. The uncomfortable feeling at the time can be further reduced. Further, the operation corresponding to sub-freezing is possible even if the user is not near the fuel cell 1.

Next, a second embodiment of the fuel cell management method will be described with reference to the flowchart shown in FIG.
In the sub-freezing operation control in the second embodiment, first, a sub-freezing prediction flag process is executed in step S200.
The below-freezing prediction flag process will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 5 is a subroutine showing the below-freezing point prediction flag process, and the below-freezing point prediction flag process is executed at regular intervals while the ignition switch 31 is OFF.

First, in step S201, the ECU 30 connects the vehicle transceiver described above to a weather information server via the Internet, and determines whether or not the current outside air temperature is below freezing point from the received weather data.
If the determination result in step S201 is “YES” (the current outside air temperature is below freezing), the process proceeds to step S202, and it is determined from the received weather data whether the predicted outside air temperature after one hour is below freezing.
If the determination result in step S202 is “YES” (predicted outside air temperature after one hour is also below freezing), the process proceeds to step S203, the subfreezing prediction flag F1 is set to “1”, and the execution of this routine is ended.
If the determination result in step S202 is “NO” (the predicted outside temperature after one hour is not below freezing), the process proceeds to step S204, the below-freezing prediction flag F1 is set to “0”, and the execution of this routine is ended.

Returning to the below freezing point operation control in FIG. 4, the process of step S200 is executed, and then the process proceeds to step S101 to determine whether the temperature (system temperature) of the fuel cell 1 detected by the temperature sensor 23 is lower than the predetermined value t1. judge. As in the first embodiment, the predetermined value t1 is set to a temperature slightly higher than 0 ° C. (for example, 7 ° C.). If the determination result in step S101 is “YES” (lower than t1), step In S107, it is determined whether or not the below-freezing prediction flag F1 is “1”.
If the determination result in step S107 is “YES” (F1 = 1), it is predicted that at least a part of the fuel cell 1 will be below freezing point while the fuel cell 1 is stopped, and the process proceeds to step S102. Since the processes in steps S102 to S106 are the same as those in the first embodiment, description thereof is omitted.
When the determination result in step S101 is “NO” (t1 or more) and when the determination result in step S107 is “NO” (F1 = 0), the fuel cell 1 is below freezing point while the fuel cell 1 is stopped. Since it is predicted that there will be no freezing operation and no freezing operation is necessary, execution of this routine is terminated.

  In the case of the below-freezing operation control according to the second embodiment, whether or not at least a part of the fuel cell 1 is below freezing is determined based on the current outside temperature obtained from the weather data and the predicted outside temperature one hour later. Because it predicts, the reliability of sub-freezing prediction is high.

Next, a third embodiment of the fuel cell management method will be described with reference to the flowchart shown in FIG.
In the sub-freezing operation control in the third embodiment, first, a sub-freezing prediction flag process is executed in step S300.
The below-freezing prediction flag process will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 7 is a subroutine showing the below-freezing point prediction flag process. The below-freezing point prediction flag process is executed at regular intervals while the ignition switch 31 is OFF.

First, in step S301, based on the temperature (system temperature) of the fuel cell 1 detected by the temperature sensor 23, it is determined whether or not the decreasing gradient of the fuel cell temperature is larger than a predetermined value α.
When the determination result in step S301 is “YES” (temperature gradient> α), the process proceeds to step S302, the below-freezing point prediction flag F2 is set to “1”, and the execution of this routine is ended.
When the determination result in step S301 is “NO” (temperature gradient ≦ α), the process proceeds to step S303, the below-freezing point prediction flag F2 is set to “0”, and the execution of this routine is ended.

Returning to the below freezing point operation control of FIG. 6, the process of step S109 is executed, and then the process proceeds to step S101 to determine whether or not the temperature (system temperature) of the fuel cell 1 detected by the temperature sensor 23 is lower than a predetermined value t1. judge. As in the first embodiment, the predetermined value t1 is set to a temperature slightly higher than 0 ° C. (for example, 7 ° C.). If the determination result in step S101 is “YES” (lower than t1), step In S108, it is determined whether or not the below-freezing point prediction flag F2 is “1”.
If the determination result in step S108 is “YES” (F2 = 1), it is predicted that at least a part of the fuel cell 1 will be below freezing point while the fuel cell 1 is stopped, and the process proceeds to step S102.
If the determination result in step S108 is “NO” (F2 = 0), the process proceeds to step S109 to determine whether or not the temperature (system temperature) of the fuel cell 1 detected by the temperature sensor 23 is lower than the predetermined value t2. To do. The predetermined value t2 is set to a temperature lower than the predetermined value t1 and slightly higher than 0 ° C. (for example, 3 ° C.). If the determination result in step S109 is “YES” (lower than t2), step S102 is performed. Proceed to
Since the processes in steps S102 to S106 are the same as those in the first embodiment, description thereof is omitted.
When the determination result in step S101 is “NO” (t1 or more) and when the determination result in step S109 is “NO” (t2 or more), the fuel cell 1 is below freezing point while the fuel cell 1 is stopped. Since it is predicted that this will not occur, and no freezing operation is necessary, the execution of this routine is terminated.

  In the case of the sub-freezing operation control according to the third embodiment, the first freezing point prediction for the fuel cell 1 is performed based on the temperature drop gradient of the fuel cell 1, and the freezing point is predicted by the first freezing point prediction. If not, since the second-stage freezing point prediction for the fuel cell 1 is performed based on the temperature of the fuel cell 1 (step S109), the reliability of the below-freezing point prediction is higher than in the first embodiment.

In the above-described first to third embodiments, the below-freezing point prediction unit is realized by the ECU 30 executing the processes of steps S101, S107, S108, S109, S200, and S300, and the below-freezing point is performed by executing the process of step S102. The notifying means is realized, the corresponding operation instruction means is realized by executing the processing of step S103, and the sub-freezing corresponding operating means is realized by executing step S104 or step S105.
In the embodiment described above, the anode off-gas temperature is substituted as the temperature of the fuel cell 1, but the temperature of the air discharged from the fuel cell 1 may be substituted, or the temperature of the fuel cell 1 may be directly detected. .

1 is a schematic configuration diagram of a fuel cell system according to the present invention. It is the figure which showed typically communication with the operation manager of a fuel cell, and a fuel cell system. 5 is a flowchart (Example 1) showing sub-freezing corresponding operation control for a fuel cell. 10 is a flowchart (Example 2) showing sub-freezing corresponding operation control for a fuel cell. It is a flowchart which shows the freezing point prediction flag process in Example 2. 10 is a flowchart (third embodiment) illustrating sub-freezing corresponding operation control for a fuel cell. 12 is a flowchart illustrating a sub-freezing point prediction flag process according to the third embodiment.

Explanation of symbols

1 Fuel cell 5 Fuel gas flow path (reactive gas flow path)
6 Oxidant gas flow path (reactive gas flow path)

Claims (4)

A fuel cell that generates electricity by reaction of the reaction gas; and
A sub-freezing prediction means for predicting whether or not at least a part of the fuel cell is below freezing point when the fuel cell is stopped;
A freezing point notification means for notifying the operation manager of the fuel cell of the prediction when the freezing point prediction means predicts that the freezing point will be below freezing;
A sub-freezing operation means for performing a predetermined sub-freezing operation on the fuel cell before the fuel cell is below freezing;
A fuel cell system comprising: The sub-freezing operation means is capable of a plurality of sub-freezing operation,
Corresponding driving instruction means for instructing one of the plurality of below-freezing corresponding driving,
2. The fuel cell system according to claim 1, wherein the sub-freezing operation unit performs sub-freezing operation according to an instruction of the corresponding operation instruction unit.   The sub-freezing operation includes at least one of a warm-up operation by restarting the fuel cell and a scavenging operation for scavenging a reaction gas flow path of the fuel cell. 3. The fuel cell system according to 2.   When at least part of the fuel cell is predicted to be below freezing while the fuel cell is stopped, the fuel cell operation manager is notified of the prediction, and the fuel cell is informed before the fuel cell is below freezing. A method for managing a fuel cell, comprising performing a corresponding sub-freezing operation.

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