JP2022114340A - fuel cell system - Google Patents

Abstract

To determine whether a motor-operated valve for controlling pressure and a flow rate of oxidant gas or the like supplied to a fuel cell while suppressing increase in manufacturing costs in a fuel cell system.SOLUTION: A fuel cell system 1 includes an air regulation valve ARV for changing an aperture in accordance with a current flowing into a motor and a control unit 3 for controlling a current flowing into the motor to a target current corresponding to a target aperture of the air regulation valve ARV by applying predetermined voltage V to the motor at a predetermined duty ratio r. The control unit 3, in voltage application time, applies the predetermined voltage V to the motor at a predetermined duty ratio r', and in monitoring time in which a current generated by voltage applied in voltage application time can be detected, determines that the air regulation valve ARV is in an abnormal state when a current I flowing into the motor is less than or equal to a threshold I.SELECTED DRAWING: Figure 1

Description

The present invention relates to fuel cell systems.

As a fuel cell system, an electric valve whose degree of opening changes when driven by a stepping motor is used to control the pressure and flow rate of the oxidant gas supplied to the fuel cell, and the current flowing through the stepping motor is below a threshold value. , it may be determined that the motor-operated valve is in an abnormal state. As a related technology, there is Patent Document 1.

JP 2018-054585 A

However, in the above fuel cell system, the stepping motor is relatively expensive, so there is a concern that the manufacturing cost will increase.

SUMMARY OF THE INVENTION Accordingly, it is an object of one aspect of the present invention to determine whether or not an electrically operated valve is abnormal while suppressing an increase in manufacturing costs in a fuel cell system.

A fuel cell system, which is one embodiment of the present invention, includes a motor-operated valve whose degree of opening changes according to current flowing through a motor, and a motor-operated valve that applies a predetermined voltage at a first predetermined duty ratio to the motor. a control unit for controlling the flowing current to a target current corresponding to the target opening of the electric valve, wherein the control unit applies the predetermined voltage to the motor at a second predetermined duty ratio during the voltage application time. In addition, when the current flowing through the motor or the variation width of the current flowing through the motor per unit time is equal to or less than a threshold during the monitoring time during which the current generated by the voltage applied during the voltage application time can be detected, the motor-operated valve is It is judged to be in an abnormal state.

As a result, it is possible to determine whether or not the motor-operated valve, whose degree of opening changes according to the current flowing through the motor, is in an abnormal state. It is possible to suppress an increase in the manufacturing cost of the fuel cell system.
Also, the electric valve may be a butterfly valve.

In general, the butterfly valve can be easily applied as a motor-operated valve because the degree of opening of the butterfly valve can be changed according to the current flowing through the motor.

Further, the motor-operated valve is used to supply oxidant gas to the fuel cell, and the control unit controls the operation of the motor-operated valve after the fuel cell is instructed to start and the fuel gas is supplied to the fuel cell. It may be configured to supply the oxidant gas to the fuel cell when it is determined that the state is not met.

As a result, after the fuel cell is instructed to start, the fuel gas in the fuel cell is insufficient compared to the case where the motor-operated valve determines that there is no abnormality and the oxidant gas is supplied to the fuel cell before the fuel gas is supplied. Since it is possible to suppress the oxidant gas from being supplied to the fuel cell in this state, it is possible to suppress deterioration of the fuel cell. In addition, it is possible to smoothly carry out the processing from when it is determined that the motor-operated valve is not in an abnormal state to when the fuel cell starts to generate power.

According to the present invention, in a fuel cell system, it is possible to determine whether or not an electric valve that controls the pressure and flow rate of an oxidant gas or the like supplied to a fuel cell is abnormal while suppressing an increase in manufacturing costs. can be done.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the fuel cell system of embodiment. FIG. 3 is a diagram showing an example of voltage applied to a motor and current flowing through the motor; FIG. 3 is a diagram showing an example of voltage applied to a motor and current flowing through the motor; 4 is a flow chart showing an example of the operation of a control unit;

Embodiments will be described in detail below with reference to the drawings.
FIG. 1 is a diagram showing an example of a fuel cell system according to an embodiment.

A fuel cell system 1 shown in FIG. 1 is mounted on an industrial vehicle such as a forklift or a vehicle Ve such as an automobile, and supplies electric power to a load Lo and the like. It should be noted that the load Lo is an inverter, electrical components, and the like that drive a running motor mounted on the vehicle Ve.

Further, the fuel cell system 1 includes a fuel cell FC, a hydrogen tank HT, an injector INJ, an air compressor ACP, an air pressure regulating valve ARV (motorized valve), an air shutoff valve ASV (motorized valve), and an exhaust and drain valve. An EDV (electrically operated valve), a DCDC converter CNV, a power storage device B, a storage unit 2, and a control unit 3 are provided.

A fuel cell FC is a fuel cell stack composed of a plurality of fuel cells connected in series with each other. Electricity is generated by an electrochemical reaction.

The hydrogen tank HT is a fuel gas storage container. The fuel gas stored in the hydrogen tank HT is supplied to the fuel cell FC through the injector INJ.

The injector INJ adjusts the flow rate of fuel gas supplied to the fuel cell FC.
The air compressor ACP supplies oxidant gas to the fuel cell FC.

The air pressure regulating valve ARV is a butterfly valve whose degree of opening changes according to the torque of the motor, and adjusts the pressure and flow rate of the oxidant gas supplied from the air compressor ACP to the fuel cell FC via the air shut valve ASV. It should be noted that the motor provided in the air pressure regulating valve ARV is composed of a DC motor or the like, and the torque of the motor increases as the current flowing through the motor increases. For example, when no current flows through the motor, that is, when the torque of the motor is zero, the opening of the air pressure regulating valve ARV is held at zero by a spring (not shown) provided in the air pressure regulating valve ARV. . Further, when a target current is flowing through the motor, that is, when the torque of the motor is the target torque, the biasing force of the spring and the torque of the motor are in balance, and the opening of the air pressure regulating valve ARV is held at the target opening. shall be That is, it is assumed that the opening degree of the air pressure regulating valve ARV changes according to the current flowing through the motor.

The air shut valve ASV is a butterfly valve whose degree of opening changes according to the torque of the motor, and cuts off the oxidant gas supplied from the air compressor ACP to the fuel cell FC. The motor provided for the air shut valve ASV is composed of a direct current motor or the like like the motor provided for the air pressure regulating valve ASV. do.

The exhaust/drain valve EDV is a butterfly valve whose degree of opening changes according to the torque of the motor, and adjusts the flow rate of hydrogen gas and water discharged from the fuel cell FC to the outside. The motor provided for the exhaust/drain valve EDV is composed of a DC motor or the like, similar to the motor provided for the air pressure regulating valve ARV. do.

The DCDC converter CNV is provided between the fuel cell FC and the power storage device B, and supplies the power storage device B with electric power output from the fuel cell FC.

The power storage device B is configured by a lithium ion capacitor or the like, and supplies power to the load Lo.

The storage unit 2 is configured by a memory such as a RAM (Random Access Memory), and stores a predetermined duty ratio r, a predetermined duty ratio r', a voltage application time, a monitoring time, a threshold value Ith, and the like, which will be described later.

The control unit 3 is composed of a microcomputer or the like, and when the fuel cell FC is instructed to start, electric power corresponding to the voltage of the power storage device B is supplied from the fuel cell FC to the power storage device B via the DCDC converter CNV. , the injector INJ, the air compressor ACP, the air pressure regulating valve ARV, the air shut valve ASV, the exhaust drain valve EDV, and the DCDC converter CNV. In addition, the activation instruction includes the case where the operator of the vehicle Ve issues an instruction to activate the vehicle Ve, the case where the operator directly issues an instruction to activate the fuel cell system 1, and the case where the fuel cell system 1 is activated by a timer or the like incorporated in the control unit 3. It includes the case where the system 1 is spontaneously activated by the control unit 3 .

For example, the control unit 3 applies a predetermined voltage V at a predetermined duty ratio r (first predetermined duty ratio) to a motor provided in the air pressure regulating valve ARV, thereby adjusting the current flowing through the motor to the target opening degree of the air pressure regulating valve ARV. is controlled to the target current corresponding to It should be noted that the predetermined duty ratio r is defined as the ratio between the constant time T1 and the constant time T2 when the motor of the air pressure regulating valve ARV is repeatedly applied with the predetermined voltage V for the constant time T1 and then the voltage is not applied to the motor for the constant time T2. percentage.

Here, FIG. 2(a) is a diagram showing an example of the voltage applied to the motor when controlling the current flowing through the motor to the target current. The horizontal axis of the two-dimensional coordinates shown in FIG. 2A indicates time, and the vertical axis indicates voltage. Further, the solid line shown in FIG. 2(a) indicates the voltage applied to the motor. FIG. 2B is a diagram showing an example of the current flowing through the motor when the current flowing through the motor is controlled to the target current. The horizontal axis of the two-dimensional coordinates shown in FIG. 2B indicates time, and the vertical axis indicates current. Further, the solid line shown in FIG. 2(b) indicates the current flowing through the motor. The dashed line shown in FIG. 2(b) indicates the moving average of the current flowing through the motor.

2(a) and 2(b), a predetermined voltage V is applied to the motor of the air pressure regulating valve ARV at a predetermined duty ratio r, so that the moving average of the current flowing through the motor gradually increases from zero to the target current. It is rising. That is, it is assumed that the current flowing through the motor is controlled to the target current by applying a predetermined voltage V with a predetermined duty ratio r to the motor of the air pressure regulating valve ARV.

Further, the control unit 3 applies a predetermined voltage to the motor of the air pressure regulating valve ARV at a predetermined duty ratio r' (second predetermined duty ratio) during the voltage application time, and applies the voltage at the same start time as the voltage application time. If the current flowing through the motor of the air pressure regulating valve ARV becomes larger than the threshold value Ith during the monitoring time longer than the time, it is determined that the air pressure regulating valve ARV is in a normal state (the power line of the motor of the air pressure regulating valve ARV is not disconnected). to decide. The predetermined duty ratio r' is the ratio of the constant time T2 to the constant time T1. It is also assumed that the voltage application time is obtained in advance based on the characteristics indicating the relationship between the voltage applied to the motor and the current flowing through the motor, noise contained in the current flowing through the motor, and the like. The monitoring time is the timing when the current flowing through the motor reaches its maximum value with a delay after the predetermined voltage V is applied to the motor at a predetermined duty ratio r' when the motor of the air pressure regulating valve ARV is in a normal state. It is assumed that it is set in advance so that Further, the threshold value Ith is based on the maximum value of the current that flows through the motor with a delay after the predetermined voltage V is applied to the motor at the predetermined duty ratio r' when the motor of the air pressure regulating valve ARV is in a normal state. It is assumed that it is set in advance.

Further, the control unit 3 applies a predetermined voltage V at a predetermined duty ratio r' to the motor of the air pressure regulating valve ARV during the voltage application time, and the current flowing through the motor of the air pressure regulating valve ARV is equal to or less than the threshold value Ith during the monitoring time. , it is determined that the air pressure regulating valve ARV is in an abnormal state (the power line of the motor of the air pressure regulating valve ARV is disconnected).

Here, FIG. 3A is a diagram showing an example of the current flowing through the motor when the predetermined duty ratio r' of the predetermined voltage V applied to the motor and the air pressure regulating valve ARV are in a normal state. The horizontal axis of the two-dimensional coordinates shown in FIG. 3(a) indicates time, and the vertical axis indicates the predetermined duty ratio r' or current. The dashed line shown in FIG. 3(a) indicates the predetermined duty ratio r', and the solid line indicates the current flowing through the motor.

In FIG. 3A, the predetermined duty ratio r' of the voltage application time is 100[%]. Also, the current flowing through the motor is greater than the threshold Ith during part of the monitoring time. Note that the predetermined duty ratio r' is not limited to 100[%] as long as it is a value that allows the current flowing through the motor to be greater than the threshold value Ith within the monitoring time when the air pressure regulating valve ARV is in a normal state.

FIG. 3B is a diagram showing an example of the current flowing through the motor when the predetermined duty ratio r' of the predetermined voltage V applied to the motor and the air pressure regulating valve ARV are in an abnormal state. The horizontal axis of the two-dimensional coordinates shown in FIG. 3(b) indicates time, and the vertical axis indicates the predetermined duty ratio r' or current. Also, the dashed line shown in FIG. 3(b) indicates the predetermined duty ratio r', and the solid line indicates the current flowing through the motor.

In FIG. 3B, the predetermined duty ratio r' of the voltage application time is 100[%]. In addition, the current flowing through the motor is almost zero during the entire monitoring time.

FIG. 4 is a flow chart showing an example of the operation of the control unit 3 when performing power generation start processing of the fuel cell FC.

First, when the fuel cell FC is instructed to start (step S1: Yes), the control unit 3 measures the voltage applied to the motor of various sensors (not shown) provided in the fuel cell system 1 (air pressure regulating valve ARV). sensor, a sensor for measuring the current flowing in the motor of the air pressure regulating valve ARV, etc.) and various switches (such as a switch connected between the DCDC converter CNV and the power storage device B) are in a normal state ( step S2).

Next, when the controller 3 determines that various sensors and switches are in an abnormal state (step S2: No), the controller 3 notifies the user of the occurrence of an error (step S3), and controls power generation of the fuel cell FC. End start processing.

On the other hand, when the control unit 3 determines that various sensors and various switches are in a normal state (step S2: Yes), the control unit 3 starts supplying the fuel gas to the fuel cell FC (step S4), and ends the supply of the fuel gas. Then (step S5: Yes), the motor of the air pressure regulating valve ARV is applied with a predetermined voltage V at a predetermined duty ratio r' during the voltage application time, and the current flowing through the motor of the air pressure regulating valve ARV is acquired during the monitoring time. (Step S6).

Next, when the current obtained in step S6 is greater than the threshold value Ith (step S7: Yes), the control unit 3 starts power generation of the fuel cell FC by starting the supply of the oxidant gas to the fuel cell FC. (Step S8).

On the other hand, when the current obtained in step S6 is equal to or less than the threshold value Ith (step S7: No), the control unit 3 determines that the air pressure regulating valve ARV is in an abnormal state (step S9), and an error occurs. The user is notified of the presence (step S10), and the power generation start processing of the fuel cell FC ends.

During the monitoring time, the control unit 3 acquires the fluctuation range per unit time of the current flowing through the motor of the air pressure regulating valve ARV. It may be configured to determine that Note that the threshold ΔIth is the variation per unit time of the current flowing through the motor with a delay after the predetermined voltage V is applied to the motor at the predetermined duty ratio r′ when the motor of the air pressure regulating valve ARV is in a normal state. It shall be set in advance based on the maximum width.

As described above, in the fuel cell system 1 of the embodiment, during the voltage application time, the predetermined voltage V is applied to the motor of the air pressure regulating valve ARV at a predetermined duty ratio r', and during the monitoring time, the current flowing through the motor reaches the threshold Ith or less, or when the variation per unit time of the current flowing through the motor is equal to or less than the threshold value ΔIth, it is determined that the air pressure regulating valve ARV is in an abnormal state. As a result, it is possible to determine whether or not the air pressure regulating valve ARV, whose degree of opening changes according to the current flowing through the motor, is in an abnormal state. A motor can be employed, and an increase in manufacturing cost of the fuel cell system 1 can be suppressed.

Further, in the fuel cell system 1 of the embodiment, the air pressure regulating valve ARV is configured as a butterfly valve. In general, the butterfly valve can be easily applied as the air pressure regulating valve ARV because the opening degree of the butterfly valve can be changed according to the current flowing through the motor. In addition, since the butterfly valve has a restoring force such as a spring acting in the direction of closing the valve, even if a current is applied to the motor of the air pressure regulating valve ARV at the second predetermined duty ratio, the degree of opening of the butterfly valve will be affected. hard to give

Further, in the fuel cell system 1 of the embodiment, after the fuel cell FC is instructed to start and the fuel gas is supplied to the fuel cell FC, when it is determined that the air pressure regulating valve ARV is not in an abnormal state, the oxidant gas is supplied to the fuel cell FC. It is a configuration to supply. As a result, compared with the case where the air pressure regulating valve ARV is determined not to be in an abnormal state and the fuel gas is supplied after the oxidant gas is supplied to the fuel cell FC, the fuel gas in the fuel cell FC is insufficient. Since the supply of the oxidant gas to the fuel cell FC can be suppressed, deterioration of the fuel cell FC can be suppressed. In addition, it is possible to smoothly perform the processing from when it is determined that the air pressure regulating valve ARV is not in an abnormal state to when the power generation of the fuel cell FC is started.

The present invention is not limited to the above embodiments, and various improvements and modifications are possible without departing from the gist of the present invention.

For example, the control unit 3 applies a predetermined voltage V at a predetermined duty ratio r' to the motor of the air shut valve ASV during the voltage application time, and the current flowing through the motor of the air shut valve ASV is equal to or less than the threshold value Ith during the monitoring time. , or when the variation per unit time of the current flowing through the motor of the air shut valve ASV is equal to or less than the threshold value ΔIth, it may be determined that the air shut valve ASV is in an abnormal state.

Further, the control unit 3 applies the predetermined voltage V to the motor of the exhaust/drain valve ECV at a predetermined duty ratio r' during the voltage application time, and the current flowing through the motor of the exhaust/drain valve EDV is equal to or less than the threshold value Ith during the monitoring time. , or when the variation per unit time of the current flowing through the motor of the exhaust/drain valve EDV is equal to or less than the threshold value ΔIth, it may be determined that the exhaust/drain valve EDV is in an abnormal state.

Also, the start time of the monitoring time does not have to be the same start time as the voltage application time. That is, when the motor of the air pressure regulating valve ARV is in a normal state, the monitoring time is the time during which the current flowing through the motor can be detected with a delay after the predetermined voltage V is applied to the motor at the predetermined duty ratio r' for the voltage application time. The start time should be set so as to satisfy the requirement.

1 Fuel cell system 2 Storage unit 3 Control unit Ve Vehicle Lo Load FC Fuel cell HT Hydrogen tank INJ Injector ACP Air compressor ARV Air pressure control valve ASV Air shut valve EDV Exhaust drain valve CNV DCDC converter B Power storage device

Claims (3)

a motor-operated valve whose degree of opening changes according to the current flowing through the motor;
a control unit that applies a predetermined voltage to the motor at a first predetermined duty ratio to control current flowing through the motor to a target current corresponding to a target opening of the electric valve;
with
The control unit applies the predetermined voltage to the motor at a second predetermined duty ratio during the voltage application time, and applies the voltage to the motor during the monitoring time during which a current generated by the voltage applied during the voltage application time can be detected. A fuel cell system, wherein the motor-operated valve is determined to be in an abnormal state when a fluctuation range per unit time of the current flowing or the current flowing to the motor is equal to or less than a threshold value. The fuel cell system according to claim 1,
A fuel cell system, wherein the electric valve is a butterfly valve. 3. The fuel cell system according to claim 1 or 2,
The electric valve is used to supply oxidant gas to the fuel cell,
The control unit supplies oxidant gas to the fuel cell when it is determined that the motor-operated valve is not in an abnormal state after the fuel cell is instructed to start and the fuel gas is supplied to the fuel cell. fuel cell system.

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