Fuel battery system

Abstract

To provide a fuel battery system capable of reducing a discomfort applied to a crew member of a mobile body.SOLUTION: A fuel battery system 10 comprises: a fuel battery 20 that supplies a power to a motor 90 that drives a mobile body M; an air compressor 41 that supplies an oxide gas to the fuel battery 20; a power accumulation device 60 that is charged by a residual power of the fuel battery 20 in the case where a power to be generated of the fuel battery 20 is larger than a request power to be requested by the motor 90, and supplies a power to the motor 90 in the case where the power to be generated of the fuel battery 20 is smaller than the request power; and a control unit 70 that controls an operation of the air compressor 41. The control unit 70 gradually reduces a supply amount of the oxygen gas in accordance with an increase of a charging amount of the power accumulation device 60, and on the other hand, controls the operation of the air compressor 41 so as to gradually increase the supply amount of the oxygen gas in accordance with the reduction of the charging amount of the power accumulation device 60.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel cell system. [Background technology]

[0002] Patent Document 1 discloses a fuel cell system that includes a fuel cell, a secondary battery, an air compressor, and a control device. The fuel cell supplies power to a main drive motor that drives a vehicle. The secondary battery is charged with power from the fuel cell and power obtained by regeneration by the main drive motor, and functions as a power source for driving the main drive motor. The air compressor supplies air to the fuel cell. The control device controls the operation of the air compressor so that the amount of air supplied to the fuel cell increases as the amount of power generation required of the fuel cell increases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-10901 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, as the amount of air supplied by the air compressor increases, the operating noise of the air compressor may become louder, which may cause discomfort to vehicle occupants. For this reason, it is desirable to reduce the discomfort caused to the occupants. [Means for solving the problem]

[0005] A fuel cell system for solving the above problem is a fuel cell system mounted on a moving body, and includes a fuel cell that supplies power to a motor that drives the moving body, an air compressor that supplies oxidant gas to the fuel cell, a power storage device that is charged with surplus power from the fuel cell when the power generated by the fuel cell is greater than the required power of the motor, and supplies power to the motor when the power generated by the fuel cell is less than the required power, and a control unit that controls the operation of the air compressor, wherein the control unit controls the operation of the air compressor to gradually reduce the amount of oxidant gas supplied in response to an increase in the charge level of the power storage device, and to gradually increase the amount of oxidant gas supplied in response to a decrease in the charge level of the power storage device.

[0006] According to the above configuration, the supply amount of oxidant gas is gradually decreased as the charge amount of the power storage device increases, while the supply amount of oxidant gas is gradually increased as the charge amount of the power storage device decreases. Therefore, when the charge amount of the power storage device is sufficient, it is possible to prevent an excessive supply of oxidant gas to the fuel cell. This makes it possible to reduce the operating noise of the air compressor. Therefore, it is possible to reduce the discomfort felt by the occupants of the mobile object. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a mobile object on which a fuel cell system according to an embodiment is mounted. [Diagram 2] FIG. 2 is a graph showing an example of the relationship between the charge amount of the power storage device and the output rate of the air compressor in the output limiting process. [Diagram 3] FIG. 3 is a diagram showing the output limiting process when a moving object is moving. [Figure 4] FIG. 4 is a diagram showing the output limiting process when the moving body is stopped. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, one embodiment of a fuel cell system will be described with reference to FIGS. The fuel cell system 10 is mounted on a moving object M that is configured to be movable by adding an assist driving force from a motor 90 to a driving force driven by a human passenger. The moving object M is, for example, an electrically assisted bicycle.

[0009] The moving object M includes a fuel cell system 10, an inverter 80, and a motor 90. The inverter 80 converts DC power supplied from the fuel cell system 10 into AC power and outputs it to the motor 90. The motor 90 is, for example, a three-phase AC motor for driving the moving object M.

[0010] (Fuel Cell System 10) As shown in FIG. 1, the fuel cell system 10 includes a fuel cell 20, a fuel gas supply unit 30, an oxidizing gas supply unit 40, a DC / DC converter 50, a power storage device 60, and a control unit .

[0011] (fuel cell 20) The fuel cell 20 is configured by stacking a plurality of unit cells (not shown) each having a membrane electrode assembly. The fuel cell 20 generates power by an electrochemical reaction between a fuel gas and an oxidizing gas. The fuel gas is, for example, hydrogen gas. The oxidizing gas is, for example, air.

[0012] (Fuel gas supply unit 30) The fuel gas supply unit 30 supplies fuel gas to the fuel cell 20. The fuel gas supply unit 30 has a canister 31 that stores the fuel gas.

[0013] The fuel gas supply unit 30 has a fuel gas supply pipe 32 that connects the canister 31 and the fuel cell 20, and a solenoid valve 33 provided on the fuel gas supply pipe 32. The amount of fuel gas supplied to the fuel cell 20 is controlled by opening and closing the solenoid valve 33.

[0014] The fuel gas supply unit 30 has a fuel gas discharge pipe 34 connected to the fuel cell 20, and a solenoid valve 35 provided in the fuel gas discharge pipe 34. The amount of fuel gas discharged from the fuel cell 20 is controlled by driving the solenoid valve 35 to open and close.

[0015] (Oxidizing gas supply unit 40) The oxidizing gas supply unit 40 supplies the oxidizing gas to the fuel cell 20. The oxidizing gas supply unit 40 has an air compressor 41 that compresses and sends air to the fuel cell 20. The air compressor 41 is driven by a drive motor (not shown).

[0016] The oxidant gas supply unit 40 has an oxidant gas supply pipe 42 that connects the air compressor 41 and the fuel cell 20, and an electromagnetic valve 43 provided on the oxidant gas supply pipe 42. The amount of oxidant gas supplied to the fuel cell 20 is controlled by driving the drive motor of the air compressor 41 and opening and closing the electromagnetic valve 43.

[0017] The oxidizing gas supply unit 40 has an oxidizing gas discharge pipe 44 connected to the fuel cell 20, and an electromagnetic valve 45 provided in the oxidizing gas discharge pipe 44. The discharge amount of the oxidizing gas from the fuel cell 20 is controlled by driving the electromagnetic valve 45 to open and close.

[0018] (DC / DC converter 50) The DC / DC converter 50 is electrically connected to the fuel cell 20. The DC / DC converter 50 transforms and outputs the DC power generated by the fuel cell 20. The DC / DC converter 50 is electrically connected to a power storage device 60 and an inverter 80.

[0019] (Electricity storage device 60) The power storage device 60 is connected in parallel to the inverter 80. The power storage device 60 is, for example, a secondary battery such as a lithium ion battery.

[0020] The power storage device 60 is charged by the surplus power of the fuel cell 20 when the power generated by the fuel cell 20 is greater than the power required by the motor 90. This increases the amount of charge in the power storage device 60. The power storage device 60 is also charged by the regenerative power of the motor 90. On the other hand, the power storage device 60 supplies power to the motor 90 when the power generated by the fuel cell 20 is less than the power required by the motor 90. This reduces the amount of charge in the power storage device 60. The amount of charge in the power storage device 60 can also be referred to as a charging rate, which is the ratio of the remaining capacity to the full charge capacity of the power storage device 60.

[0021] (Control unit 70) The control unit 70 controls the supply amount and discharge amount of the fuel gas by controlling the operation of the solenoid valves 33, 35 provided in the fuel gas supply pipe 32 and the fuel gas discharge pipe 34, respectively. The control unit 70 controls the supply amount and discharge amount of the oxidant gas by controlling the operation of the solenoid valves 43, 45 provided in the oxidant gas supply pipe 42 and the oxidant gas discharge pipe 44, respectively.

[0022] The control unit 70 determines the amount of power generated by the fuel cell 20 based on the power required by the motor 90. The control unit 70 controls the amount of fuel gas supplied to the fuel cell 20 by controlling the opening and closing state of the solenoid valve 33 based on the amount of power generated by the fuel cell 20. The control unit 70 controls the amount of oxidant gas supplied to the fuel cell 20 by controlling the output of the drive motor of the air compressor 41 and the opening and closing state of the solenoid valve 43 based on the amount of power generated by the fuel cell 20.

[0023] The control unit 70 controls the operation of the DC / DC converter 50 so that the generated power of the fuel cell 20 corresponds to the power required by the motor 90 . The control unit 70 controls the operation of the inverter 80, thereby controlling the rotation speed of the motor 90. Note that the inverter 80 may be controlled by a control unit different from the control unit 70.

[0024] The control unit 70 calculates the charge amount of the power storage device 60 at predetermined time intervals based on the detection result of a sensor (not shown) that detects the voltage of the power storage device 60. The control unit 70 calculates the charge amount of the power storage device 60 based on, for example, a map that defines the relationship between the voltage and the charge amount of the power storage device 60. This map is, for example, stored in advance in the control unit 70.

[0025] The control unit 70 determines whether or not the moving object M is moving at every predetermined time interval based on the output of the motor 90. The control unit 70 determines whether or not the moving object M is moving by, for example, calculating the moving speed of the moving object M based on the output of a sensor (not shown) that detects the number of rotations of the motor 90. The control unit 70 determines that the moving object M is stopped when the moving speed of the moving object M is 0, and determines that the moving object M is moving when the moving speed of the moving object M is greater than 0.

[0026] (Output limiting process) 2, the control unit 70 executes an output limiting process for gradually limiting the output of the air compressor 41, i.e., the supply amount of oxidant gas, in accordance with the charge amount of the power storage device 60. The control unit 70 executes the output limiting process, for example, regardless of the magnitude of the power required by the motor 90. In the output limiting process, the control unit 70 controls the operation of the air compressor 41 so as to gradually decrease the supply amount of oxidant gas in accordance with an increase in the charge amount of the power storage device 60, and to gradually increase the supply amount of oxidant gas in accordance with a decrease in the charge amount of the power storage device 60.

[0027] When the moving object M is moving, the control unit 70 switches the output mode of the air compressor 41 to a plurality of output modes in a stepwise manner according to the charge amount of the power storage device 60. The output mode when the moving object M is moving is switched to three stages: a high output mode, a medium output mode, and a low output mode. In the high output mode, the medium output mode, and the low output mode when the moving object M is moving, the output ratio of the air compressor 41 is set to 100%, 80%, and 70%, respectively. The output ratio of the air compressor 41 in each output mode is constant. The output ratio of the air compressor 41 is the ratio of the output to the maximum output of the drive motor of the air compressor 41.

[0028] When the moving object M is stopped, the control unit 70 switches the output mode of the air compressor 41 to a plurality of output modes in a stepwise manner according to the charge amount of the power storage device 60. The output mode when the moving object M is stopped is switched to four stages: high output mode, medium output mode, low output mode, and stop mode. Therefore, the types of output modes to be switched to when the moving object M is stopped are greater than the types of output modes to be switched to when the moving object M is moving. In the high output mode, medium output mode, low output mode, and stop mode when the moving object M is stopped, the output ratios of the air compressor 41 are set to 100%, 70%, 50%, and 0%, respectively.

[0029] (Output limiting process when moving object M is moving) 3, when the output mode of the air compressor 41 is the high output mode while the moving object M is moving, if the charge amount of the power storage device 60 becomes equal to or greater than the charge amount V11, the control unit 70 shifts the output mode to the medium output mode. The charge amount V11 is, for example, 20%.

[0030] When the output mode of the air compressor 41 is the medium output mode, the control unit 70 shifts the output mode to the low output mode when the charge amount of the power storage device 60 becomes equal to or greater than the charge amount V12. The charge amount V12 is, for example, 70%.

[0031] When the output mode of the air compressor 41 is the low output mode, the control unit 70 shifts the output mode to the medium output mode when the charge amount of the power storage device 60 becomes equal to or less than the charge amount V13. The charge amount V13 is, for example, 70%.

[0032] When the output mode of the air compressor 41 is the medium output mode, the control unit 70 shifts the output mode to the high output mode when the charge amount of the power storage device 60 becomes equal to or less than the charge amount V14. The charge amount V14 is, for example, 20%.

[0033] For the above reasons, the control unit 70 controls the operation of the air compressor 41 so as to gradually decrease the supply amount of oxidant gas in response to an increase in the charge amount of the power storage device 60 while the moving object M is moving. In addition, the control unit 70 controls the operation of the air compressor 41 so as to gradually increase the supply amount of oxidant gas in response to a decrease in the charge amount of the power storage device 60 while the moving object M is moving.

[0034] As described above, when the generated power of the fuel cell 20 is smaller than the power required by the motor 90, power is supplied from the power storage device 60 to the motor 90. Therefore, even if the output of the air compressor 41 is limited by the output limiting process, the effect on the movement of the moving object M can be reduced.

[0035] (Output limiting process when moving body M stops) 4, when the output mode of the air compressor 41 is the high output mode while the moving object M is stopped, if the charge amount of the power storage device 60 becomes equal to or greater than the charge amount V21, the control unit 70 shifts the output mode to the medium output mode. The charge amount V21 is, for example, 20%.

[0036] When the output mode of the air compressor 41 is the medium output mode, the control unit 70 shifts the output mode to the low output mode when the charge amount of the power storage device 60 becomes equal to or greater than the charge amount V22. The charge amount V22 is, for example, 50%.

[0037] When the output mode of the air compressor 41 is the low output mode, the control unit 70 transitions the output mode to the stop mode when the charge amount of the power storage device 60 becomes equal to or greater than the charge amount V23. That is, when the moving object M is stopped, if the charge amount of the power storage device 60 exceeds the charge amount V23, the control unit 70 stops the operation of the air compressor 41. The charge amount V23 is, for example, 90%. The charge amount V23 is an example of a "threshold value."

[0038] When the output mode of the air compressor 41 is the stop mode, the control unit 70 shifts the output mode to the low output mode when the charge amount of the power storage device 60 becomes equal to or less than the charge amount V24. The charge amount V24 is, for example, 90%.

[0039] When the output mode of the air compressor 41 is the low output mode, the control unit 70 shifts the output mode to the medium output mode when the charge amount of the power storage device 60 becomes equal to or less than the charge amount V25. The charge amount V25 is, for example, 50%.

[0040] When the output mode of the air compressor 41 is the medium output mode, the control unit 70 shifts the output mode to the high output mode when the charge amount of the power storage device 60 becomes equal to or less than the charge amount V26. The charge amount V26 is, for example, 20%.

[0041] For the above reasons, when the moving object M is stopped, the control unit 70 controls the operation of the air compressor 41 so as to gradually decrease the supply amount of oxidant gas in response to an increase in the charge amount of the power storage device 60. In addition, when the moving object M is stopped, the control unit 70 controls the operation of the air compressor 41 so as to gradually increase the supply amount of oxidant gas in response to a decrease in the charge amount of the power storage device 60.

[0042] The operation of this embodiment will be described. In the fuel cell system 10, the supply amount of oxidant gas is gradually decreased as the charge amount of the power storage device 60 increases, whereas the supply amount of oxidant gas is gradually increased as the charge amount of the power storage device 60 decreases. Therefore, when the charge amount of the power storage device 60 has a margin, it is possible to prevent an excessive supply of oxidant gas to the fuel cell 20.

[0043] The effects of this embodiment will be described. (1) The control unit 70 controls the operation of the air compressor 41 so as to gradually decrease the amount of oxidant gas supplied in response to an increase in the charge amount of the power storage device 60, and to gradually increase the amount of oxidant gas supplied in response to a decrease in the charge amount of the power storage device 60.

[0044] According to the above configuration, the above-mentioned effect is achieved, and therefore it is possible to reduce the operating noise of the air compressor 41. Therefore, the discomfort felt by the passengers of the moving object M can be reduced. In addition, since the supply amount of oxidant gas changes stepwise, discomfort felt by occupants due to a sudden change in the operating noise of the air compressor 41 can be reduced.

[0045] (2) When the moving object M is stopped, the control unit 70 stops the operation of the air compressor 41 if the charge amount of the power storage device 60 exceeds the charge amount V23, which is a threshold value. The electric power required by the motor 90 when the moving body M is stopped tends to be smaller than when the moving body M is moving. For this reason, when the moving body M is stopped, the supply amount of the oxidizing gas can be reduced as the charge amount of the power storage device 60 is greater compared to when the moving body M is moving.

[0046] According to the above configuration, when the charge amount of the power storage device 60 exceeds the threshold, the operation of the air compressor 41 stops. Therefore, by setting the threshold to a relatively high charge amount, when the charge amount of the power storage device 60 has a margin, the operation noise of the air compressor 41 is not generated. Therefore, the discomfort felt by the occupants of the moving object M can be further reduced.

[0047] (3) When the moving body M is stopped, the control unit 70 gradually switches the output mode of the air compressor 41 to a number of output modes, which are more diverse than the output mode of the air compressor 41 when the moving body M is moving, depending on the amount of charge of the power storage device 60.

[0048] According to the above configuration, when the moving object M is stopped, there are more types of output modes of the air compressor 41 that can be switched compared to when the moving object M is moving. As a result, when the moving object M is moving, the increase in the types of output modes is suppressed, and the control of the air compressor 41 can be suppressed from becoming complicated. Furthermore, when the moving object M is stopped, when the operating sound of the air compressor 41 is easily heard by the occupants, the number of types of output modes is increased compared to when the moving object is moving, so that the operating sound of the air compressor 41 can be reduced more precisely. Therefore, the discomfort felt by the occupants when the moving object M is stopped can be further reduced.

[0049] (4) The fuel cell system 10 is mounted on a moving body M that is configured to be movable by adding an assist driving force from a motor 90 to a driving force driven by a human passenger. According to the above configuration, an effect similar to the above-mentioned effect (1) can be achieved.

[0050] Furthermore, in an electrically assisted vehicle that can be moved only by human driving force, even if the charge level of the power storage device 60 drops rapidly with a decrease in the supply of oxidant gas, the vehicle will not become unable to move. Therefore, regardless of the power required by the motor 90, controlling the operation of the air compressor 41 is unlikely to cause any inconvenience.

[0051] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0052] The moving object M may be an electrically assisted wheelchair or a car. The number of output modes of the air compressor 41 when the moving object M is stopped and when it is moving may be the same.

[0053] The control unit 70 may not stop the operation of the air compressor 41 when the charge amount of the power storage device 60 exceeds the charge amount V23 when the moving object M is stopped. In this case, the output mode of the air compressor 41 may be a low output mode, or an output mode in which the output ratio of the air compressor 41 is smaller than that in the low output mode. In this case, the generated power of the fuel cell 20 may be supplied to other electronic devices mounted on the moving object M.

[0054] The control unit 70 may execute the output limiting process only when a predetermined operation is performed on the moving object M or a predetermined condition is satisfied. The predetermined operation is, for example, an operation by a passenger of a switch or the like provided on the moving object M. The predetermined condition is, for example, that the required power of the motor 90 is smaller than a predetermined value.

[0055] The power storage device 60 may be a secondary battery such as a lead storage battery, a nickel-cadmium battery, or a nickel-metal hydride battery, or may be a capacitor. The charge amounts V11-V14 and V21-V26 of the power storage device 60, which are thresholds for switching the output mode of the air compressor 41, may be changed as appropriate. For example, the charge amounts V11-V14 may be different values ​​from one another, and the charge amounts V21-V26 may be different values ​​from one another.

[0056] The number of output modes of the air compressor 41 when the moving object M is stopped and when it is moving may be changed as appropriate. The output ratio of the air compressor 41 in each output mode can be changed as appropriate. For example, the output ratio of the air compressor 41 in the high output mode may be less than 100%.

[0057] The output ratio of the air compressor 41 in each output mode may change according to the charge amount of the power storage device 60. For example, within the same output mode, the output ratio of the air compressor 41 may increase or decrease according to the charge amount of the power storage device 60.

[0058] The above embodiment includes the configurations described in the following supplementary notes. [Appendix 1] A fuel cell system mounted on a moving body, comprising: a fuel cell that supplies power to a motor that drives the moving body; an air compressor that supplies oxidant gas to the fuel cell; a power storage device that is charged with surplus power from the fuel cell when the power generated by the fuel cell is greater than the power required for the motor, and that supplies power to the motor when the power generated by the fuel cell is less than the power required; and a control unit that controls the operation of the air compressor, wherein the control unit controls the operation of the air compressor to gradually reduce the amount of oxidant gas supplied in response to an increase in the charge level of the power storage device, and to gradually increase the amount of oxidant gas supplied in response to a decrease in the charge level of the power storage device.

[0059] [Appendix 2] The fuel cell system described in [Appendix 1], wherein the control unit stops operation of the air compressor if the charge amount of the power storage device exceeds a threshold value when the moving body is stopped.

[0060] [Appendix 3] The fuel cell system described in [Appendix 1] or [Appendix 2], wherein the control unit, when the moving body is moving, gradually switches the output mode of the air compressor to a plurality of output modes with different supply amounts of the oxidant gas in accordance with the charge amount of the power storage device, and, when the moving body is stopped, gradually switches the output mode of the air compressor to a plurality of output modes with a greater variety than the plurality of output modes in accordance with the charge amount of the power storage device.

[0061] [Appendix 4] The fuel cell system according to any one of [Appendix 1] to [Appendix 3], which is mounted on a mobile body configured to be movable by adding an assist driving force from the motor to a human driving force from a passenger. [Explanation of symbols]

[0062] M...Moving object V11,V12,V13,V14…Charging amount V21,V22,V23,V24,V25,V26…Charging amount 10. Fuel cell system 20…fuel cell 30...Fuel gas supply section 31…Canister 32…Fuel gas supply pipe 33, 35…Solenoid valve 34…Fuel gas exhaust pipe 40...Oxidant gas supply unit 41…Air compressor 42...Oxidant gas supply pipe 43,45...Solenoid valve 44...Oxidant gas exhaust pipe 50…DC / DC converter 60...Electricity storage device 70...Control unit 80…Inverter 90…Motor

Claims

1. A fuel cell system mounted on a moving object, a fuel cell that supplies power to a motor that drives the moving body; an air compressor for supplying an oxidant gas to the fuel cell; a power storage device that is charged with surplus power from the fuel cell when the power generated by the fuel cell is greater than the power required for the motor, and that supplies power to the motor when the power generated by the fuel cell is less than the power required for the motor; A control unit for controlling the operation of the air compressor, the control unit controls the operation of the air compressor to gradually reduce the supply amount of the oxidant gas in response to an increase in the charge amount of the power storage device, and to gradually increase the supply amount of the oxidant gas in response to a decrease in the charge amount of the power storage device. Fuel cell system.

2. The control unit stops the operation of the air compressor when the charge amount of the power storage device exceeds a threshold value when the moving body is stopped. The fuel cell system according to claim 1 .

3. the control unit, when the moving body is moving, switches the output mode of the air compressor stepwise to a plurality of output modes having different supply amounts of the oxidant gas in accordance with the charge amount of the power storage device, and, when the moving body is stopped, switches the output mode of the air compressor stepwise to a plurality of output modes having a greater variety than the plurality of output modes in accordance with the charge amount of the power storage device. The fuel cell system according to claim 1 .

4. The vehicle is mounted on a moving body configured to be movable by adding an assist driving force by the motor to a human driving force by a passenger. The fuel cell system according to any one of claims 1 to 3.

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