JP2016031878A - Fuel cell system and control method of fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of a fuel cell system which is less likely to give a feeling of strangeness to a user during low load power generation, and to provide a fuel cell system and a control method of a fuel cell system.SOLUTION: A fuel cell system 1 includes a fuel cell 10, fuel gas storage means 20 for storing fuel gas, fuel gas supply piping 21, an injector 23 provided in fuel gas supply piping 21, pressure adjusting means 24 provided between the fuel gas storage means 20 and injector 23, and control means 70 for controlling the pressure adjusting means 24. The control means 70 controls the pressure adjusting means 24 in a normal power generation mode when a request power generation amount goes above a predetermined value, otherwise controls the pressure adjusting means 24 in a low load power generation mode for lowering the pressure of fuel gas supplied to injector 23, compared with that in the normal power generation mode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system and a control method for the fuel cell system.

In the fuel cell system, an injector is used as means for supplying hydrogen to the fuel cell. This injector is a device that can intermittently inject high-pressure hydrogen by operating a plunger in response to a signal from a control means.
By the way, according to the following Patent Document 1, a control method is proposed in which as the required power generation amount becomes smaller, the injector drive cycle is set longer (the duty ratio is unchanged) and the injection amount per cycle is increased.

JP 2007-165186 A

Here, when the injection amount per cycle is increased as in the technique of Patent Document 1, the operation sound of the injector (plunger sound, injection sound, etc.) increases.
On the other hand, during low-load power generation where the required power generation amount is small, the operating noise of the entire fuel cell system (for example, compressor driving noise) is lower than during normal power generation, and the operating noise of the injector is greater. There is a fear.
For this reason, at the time of low load power generation, the operation sound of the injector that was not heard during normal power generation is heard by the user, giving a sense of discomfort.

  Therefore, the present invention is an invention created in view of the above-described background, and it is an object of the present invention to provide a fuel cell system and a control method for the fuel cell system that are unlikely to give the user a sense of incongruity during low load power generation.

  As means for solving the problems, a fuel cell system according to the present invention includes a fuel cell, a fuel gas storage means for storing fuel gas, and a fuel gas supply for connecting the fuel cell and the fuel gas storage means. A pipe, an injector provided in the fuel gas supply pipe, a pressure adjusting means provided between the fuel gas storage means and the injector, and a control means for controlling the pressure adjusting means, The control means controls the pressure adjusting means in the normal power generation mode when the required power generation amount is a predetermined value or more, and when the required power generation amount is less than the predetermined value, the control means controls the pressure of the fuel gas supplied to the injector. The pressure adjusting means is controlled in a low load power generation mode that is lower than that in the mode.

  According to the above-described invention, when the required power generation amount is small and the low load power generation mode is selected, the pressure on the upstream side of the injector becomes low, and the operating noise of the injector becomes smaller than that during normal power generation. Therefore, the situation where the operating sound of the injector becomes louder than the operating sound of the entire fuel cell system is avoided, and it is difficult for the user to feel uncomfortable.

  In the invention described above, the pressure adjusting means includes a first pressure reducing device provided between the fuel gas storage means and the injector, and an open / close provided between the first pressure reducing device and the injector. A valve and a second pressure reducing device provided to bypass the on-off valve, and the control means may close the on-off valve in the low load power generation mode.

  In the invention described above, the pressure adjusting means includes a variable pressure reducing device provided between the fuel gas storage means and the injector and capable of varying a secondary side pressure, and the control means includes the low load In the power generation mode, the variable pressure reducing device may be controlled so that the pressure of the fuel gas supplied to the injector is lower than that in the normal power generation mode.

  Further, as means for solving the above problems, a fuel cell system according to the present invention includes a fuel cell, fuel gas storage means for storing fuel gas, and fuel gas connecting the fuel cell and the fuel gas storage means. A supply pipe, an injector provided in the fuel gas supply pipe, an on-off valve provided between the fuel gas storage means and the injector, bypassing the on-off valve, and when the on-off valve is opened And a decompression device that lowers the pressure of the fuel gas supplied to the injector.

  According to the above-described invention, the pressure on the upstream side of the injector can be lowered by the pressure reducing device, and the operating sound of the injector can be made smaller than that during normal power generation. Therefore, since the situation where the operating sound of the injector becomes louder than the operating sound of the entire fuel cell system is avoided, it is difficult for the user to feel uncomfortable.

  Further, as a means for solving the above problems, a control method for a fuel cell system according to the present invention comprises a fuel cell, a fuel gas storage means for storing fuel gas, the fuel cell and the fuel gas storage means. A fuel gas supply pipe to be connected; an injector provided in the fuel gas supply pipe; a pressure adjusting means provided between the fuel gas storage means and the injector; a control means for controlling the pressure adjusting means; And the control means determines whether or not the required power generation amount is equal to or greater than a predetermined value, and if it is determined that the required power generation amount is not equal to or greater than the predetermined value, A pressure reduction step of controlling the pressure adjusting means in a low load power generation mode in which the pressure is lower than that in the normal power generation mode.

  According to the above-described invention, when the required power generation amount is lower than the predetermined value, the pressure on the upstream side of the injector is lowered by the pressure reduction process, and the operating noise of the injector is smaller than that during normal power generation. Therefore, the situation where the operating sound of the injector becomes louder than the operating sound of the entire fuel cell system is avoided, and it is difficult for the user to feel uncomfortable.

  ADVANTAGE OF THE INVENTION According to this invention, the control method of a fuel cell system and a fuel cell system which do not give a user discomfort at the time of low load electric power generation can be provided.

It is a figure which shows the structure of the fuel cell system which concerns on this embodiment. It is a figure for demonstrating the relationship between the operating sound of a system, and the operating sound of an injector. 3 is a flowchart showing an operation of the fuel cell system according to the present embodiment at normal time. It is a figure which shows the structure of the fuel cell system which concerns on a modification.

Next, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, an example in which a fuel cell system is mounted on a fuel cell vehicle (moving body) driven by a motor will be described. However, the present invention is not limited to a moving body, and may be applied to a stationary facility such as a stationary type. It may be provided and is not particularly limited.

≪Configuration of fuel cell system≫
As shown in FIG. 1, the fuel cell system 1 includes a fuel cell stack 10, an anode system that supplies and discharges hydrogen (fuel gas) to and from the anode of the fuel cell stack 10, and a cathode of the fuel cell stack 10. A cathode system that supplies and discharges oxygen-containing air (oxidant gas), a power consumption system that consumes the power generated by the fuel cell stack 10, and an ECU 70 (Electronic Control Unit) that electronically controls these systems I have.

<Fuel cell stack>
The fuel cell stack 10 is configured by stacking a plurality of (for example, 200 to 400) solid polymer type single cells 11. The single cell 11 includes an MEA (Membrane Electrode Assembly) and an anode separator and a cathode separator that sandwich the MEA.

  The MEA includes an electrolyte membrane (solid polymer membrane) made of a monovalent cation exchange membrane (for example, perfluorosulfonic acid type), and an anode and a cathode sandwiching the electrolyte membrane. The anode and the cathode are mainly composed of a conductive porous material such as carbon paper, and contain a catalyst (Pt, Ru, etc.) for causing an electrode reaction in the anode and the cathode.

In the anode separator, in order to supply and discharge hydrogen to and from the anode of each MEA, a through-hole extending in the stacking direction of the single cells 11 and a groove extending in the surface direction of the single cell 11 are formed. It functions as the flow path 12.
Similarly, in the cathode separator, in order to supply and discharge air to and from the cathode of each MEA, a through hole extending in the stacking direction of the single cells 11 and a groove extending in the surface direction of the single cell 11 are formed. Functions as the internal cathode channel 13.

  When hydrogen is supplied to each anode via the internal anode flow path 12, the electrode reaction of Formula (1) occurs, and when air is supplied to each cathode via the internal cathode flow path 13, Formula (2) The electrode reaction occurs. As a result, a potential difference (OCV (Open Circuit Voltage), open circuit voltage) is generated in each single cell 11. Next, when the fuel cell stack 10 and an external load such as the motor 52 are electrically connected to extract current, the fuel cell stack 10 generates power.

2H ₂ → 4H ⁺ + 4e ⁻ (1)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)

<Anode system>
The anode system includes a high-pressure tank (fuel gas storage means) 20, a hydrogen supply pipe 21 (21a to 21e) for supplying hydrogen from the high-pressure tank 20 to the anode of the fuel cell stack 10, and an anode off-gas circulation pipe for circulating the anode off-gas. 22a, anode off-gas discharge pipes 22b and 22c for discharging anode off-gas, pressure adjusting means 24, injector 23 and ejector 25 arranged on the hydrogen supply pipe 21, and anode off-gas discharge pipe 22b. And a purge valve 26.

  The high-pressure tank 20 is a tank that can store hydrogen at an extremely high pressure, for example, 70 MPa at the maximum. The high-pressure tank 20 is provided with a main stop valve (not shown) that opens or closes under the control of the ECU 70, and hydrogen filled in the high-pressure tank 20 is supplied with hydrogen when the main stop valve is opened. It flows into the pipe 21.

  The injector 23 is an electronically controlled hydrogen injection device that intermittently injects new hydrogen from the high-pressure tank 20 from the nozzle, with the plunger moving forward and backward by PWM control of the ECU 70. The injector 23 injects hydrogen to adjust the pressure and flow rate of hydrogen flowing through the internal anode channel 12.

The pressure adjusting means 24 is configured to adjust the pressure of hydrogen that is disposed upstream of the injector 23 and supplied to the injector 23.
The pressure adjusting means 24 of the present embodiment includes a first regulator (first decompression device) 24a disposed on the downstream side of the high-pressure tank 20, and a switching valve disposed between the first regulator 24a and the injector 23. (On-off valve) 24b and a second regulator (second decompression device) 24c disposed on a bypass pipe 24d that bypasses the switching valve 24b.

The first regulator 24a and the second regulator 24c adjust (depressurize) the pressure of hydrogen flowing from the primary side (upstream side of the hydrogen supply pipe 21) to the secondary side (downstream side of the hydrogen supply pipe 21) to a predetermined pressure. It is a device for doing.
Further, the first regulator 24a and the second regulator 24c are provided with a handle for setting a predetermined pressure for hydrogen flowing to the secondary side.
In the present embodiment, the pressure on the secondary side of the first regulator 24a is set to be 1 MPa, for example, and the pressure on the secondary side of the second regulator 24c is set to be 0.5 MPa, for example. .

The switching valve 24 b is a normally open type on-off valve that opens or closes under the control of the ECU 70. When the switching valve 24b is opened, hydrogen reduced to 1 MPa by the first regulator 24a passes through the switching valve 24b and is supplied to the injector 23.
On the other hand, when the switching valve 24b is closed, the hydrogen decompressed to 1 MPa by the first regulator 24a passes through the second regulator 24c, and the hydrogen decompressed to 0.5 MPa by the second regulator 24c is passed to the injector 23. Supplied.
When the pressure supplied to the injector 23 is lowered by closing the switching valve 24b, the hammering sound and injection sound of the plunger of the injector 23 are also reduced, and the operating sound of the injector 23 is reduced ("0" in FIG. 2). .5 MPa "and" 1 MPa ").

  The anode off-gas circulation pipe 22 a is a pipe for connecting the outlet of the internal anode flow path 12 and the intake port of the ejector 25 and allowing the ejector 25 to take in the anode off-gas containing hydrogen discharged from the internal anode flow path 12.

  The ejector 25 generates a negative pressure by injecting new hydrogen from the injector 23 with a nozzle, and by this negative pressure, the anode off-gas in the anode off-gas circulation pipe 22a is sucked, and the new hydrogen and the anode off-gas are mixed. Injecting toward the internal anode flow path 12.

  The purge valve 26 is opened by the ECU 70 when discharging (purging) impurities (water vapor, nitrogen, etc.) accompanying hydrogen circulating through the anode off-gas circulation pipe 22a at the time of starting the system or generating power of the fuel cell stack 10. It is like that.

<Cathode system>
The cathode system includes a compressor 30, an air supply pipe 31 that connects the compressor 30 and the fuel cell stack 10, and a cathode offgas discharge pipe 32 that discharges the cathode offgas from the fuel cell stack 10.

  When the compressor 30 operates in accordance with a command from the ECU 70, air containing oxygen outside the vehicle is compressed by intake and sent to the air supply pipe 31, and air of a predetermined pressure is supplied to the internal cathode channel 13.

<Power consumption system>
The power consumption system includes a power controller 51 connected to an output terminal (not shown) of the fuel cell stack 10. The power controller 51 includes an electronic circuit such as a DC / DC chopper, and controls the output power (output voltage, output current) of the fuel cell stack 10 in accordance with a command from the ECU 70.

<Other equipment>
The motor 52 is an electric motor that generates a driving force for the fuel cell vehicle, and is connected to an output terminal (not shown) of the power controller 51.
The IG 61 is a start switch of the fuel cell vehicle (fuel cell system 1), and is disposed around the driver's seat. The IG 61 is connected to the ECU 70, and the ECU 70 detects an ON signal / OFF signal of the IG 61.
The accelerator opening sensor 62 detects the accelerator opening (the amount of depression of the accelerator) and outputs it to the ECU 70.

<ECU 70>
The ECU 70 is a control device that electronically controls the fuel cell system 1 and includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like. The ECU 70 controls various devices according to programs stored therein, executes various processes, and controls the various devices.

<ECU 70-power generation control function>
The ECU 70 has a power generation control function for controlling the power generation of the fuel cell stack 10 in accordance with the required power generation amount.
The ECU 70 determines the required power generation amount based on the accelerator opening (the amount of depression of the accelerator) detected by the accelerator opening sensor 62. Specifically, as the accelerator opening increases, the target anode pressure and the target cathode pressure increase, and the target anode gas flow rate (target hydrogen flow rate) and the target cathode gas flow rate (target air flow rate) increase.
It should be noted that the operating noise of the entire fuel cell system 1 increases as the required power generation amount increases (see FIG. 2).

  The ECU 70 also includes a normal power generation mode that is executed when the required power generation amount is equal to or greater than a predetermined value, and a low load power generation mode that is executed when the required load is less than the predetermined value.

  The normal power generation mode is a mode for setting the pressure of hydrogen supplied to the injector 23 to be relatively high. Specifically, control is performed to open the switching valve 24b. In addition, since the switching valve 24b in this embodiment is a normally open type, ECU70 does not issue a command in particular.

On the other hand, the low-load power generation mode is a mode for setting the pressure of hydrogen supplied to the injector 23 to be relatively low. Specifically, a control signal is transmitted to close the switching valve 24b. Control.
According to this low load power generation mode, the low load power generation mode is selected when the required power generation amount of the fuel cell stack 10 is small, such as during idling, and the pressure of hydrogen supplied to the injector 23 becomes 0.5 MPa. The operation noise becomes smaller (see FIG. 2).

As shown in FIG. 2, the predetermined value for distinguishing between the normal power generation mode and the low load power generation mode includes the operating sound of the injector 23 (when the pressure of supplied hydrogen is 1 MPa), the fuel cell system 1 Is set to the required power generation amount when the operation sound is substantially the same.
According to such a predetermined value, when the operating sound of the fuel cell system 1 is lower than the operating sound of the injector 23 (when the pressure of supplied hydrogen is 1 MPa), the low load power generation mode is selected, The operating sound of the injector 23 is reduced. For this reason, the operating sound of the injector 23 cannot be heard by the driver.
On the other hand, when the required power generation amount of the fuel cell stack 10 is high, such as when the fuel cell vehicle is traveling, the normal power generation mode is selected, and high pressure (1 MPa) hydrogen is supplied to the injector 23. For this reason, the injector 23 can supply a large amount of hydrogen to the anode at a high pressure corresponding to the required power generation amount.
Note that when the normal power generation mode is selected, the operating noise of the fuel cell system 1 is larger than the operating noise of the injector 23 that is driven when the supplied hydrogen pressure is 1 MPa, and the operating noise of the injector 23 cannot be heard by the driver.

≪Operation of fuel cell system≫
Next, the operation of the fuel cell system 1 will be described.

  The case where the IG 61 is continuously turned on and hydrogen and air are supplied to the fuel cell stack 10 will be described with reference to FIG.

  In step S101, the ECU 70 determines whether or not the required power generation amount is a predetermined value or more (determination step).

If it is determined that the required power generation amount is equal to or greater than the predetermined value (“Yes” in S101), the process of the ECU 70 proceeds to step S102 and executes the normal power generation mode.
Specifically, in step S102, the ECU 70 does not particularly issue a control signal to the switching valve 24b. As a result, the switching valve 24b is kept open, and the hydrogen reduced to 1 MPa by the first regulator 24a is supplied to the injector 23.

In step S102, the ECU 70 issues a control signal to the injector 23 and the compressor 30 so that the power generation amount of the fuel cell stack 10 becomes the required power generation amount.
As a result, the injector 23 supplies a large amount of hydrogen to the anode at a high pressure, the compressor 30 increases the drive amount to supply a large amount of air to the cathode at a high pressure, and the power generation amount of the fuel cell stack 10 is the required power generation amount. It becomes.

On the other hand, when it determines with request | requirement power generation amount not being more than predetermined value (in the case of "No" in S101), processing of ECU70 progresses to Step S103, and performs low load power generation mode (pressure reduction process).
Specifically, in step S103, the ECU 70 transmits a control signal to the switching valve 24b to close the switching valve 24b. Thereby, the hydrogen decompressed to 1 MPa by the first regulator 24 a passes through the second regulator 24 c, and the hydrogen decompressed to 0.5 MPa is supplied to the injector 23.

In step S103, the ECU 70 outputs a control signal to the injector 23 and the compressor 30 so that the power generation amount of the fuel cell stack 10 becomes the required power generation amount.
The injector 23 supplies a small amount of hydrogen to the anode at a low pressure, and the compressor 30 reduces the driving amount to supply a small amount of air to the cathode at a low pressure.

    And after each process of step S102 and step S103, the process of ECU70 returns to a start via a return.

  As described above, according to the fuel cell system 1 and the control method according to the present embodiment, the low load power generation mode is executed when the required power generation amount is smaller than the predetermined value, and the operation sound of the injector 23 is activated by the operation of the fuel cell system 1. Smaller than sound. For this reason, since the situation where the operating sound of the injector 23 can be heard by the user during low load power generation is avoided, it is difficult to give the user a sense of incongruity.

Although the fuel cell system 1 and the control method according to the embodiment have been described above, the present invention is not limited to the example described in the embodiment.
For example, regarding the second regulator 24c, the pressure on the secondary side is set to 0.5 MPa, but the present invention only needs to be able to reduce the pressure lower than the pressure (1 MPa) on the secondary side of the first regulator 24a.
However, if the pressure on the secondary side of the second regulator 24c is too low, the hydrogen supply by the injector 23 may not be appropriately performed, and the sonic velocity supply by the injector 23 needs to be within a possible range.

Further, as shown in FIG. 4, the pressure adjusting unit 24 according to the present invention may be a variable pressure reducing device 24 </ b> A that can change the pressure on the secondary side under the control of the ECU 70.
Even with such a configuration, the same effects as those of the fuel cell system 1 of the embodiment can be exhibited, and the number of components can be reduced as compared with the embodiment, and the fuel cell system 1A can be downsized.
As a specific configuration of the variable pressure reducing device 24A, a pressure signal on the secondary side is adjusted by changing a flow path width on the secondary side in response to a control signal from the ECU 70, or a duty ratio for opening and closing the valve. The pressure on the secondary side can be regulated by changing.

  Moreover, the pressure adjusting means 24 according to the present invention may be configured by a switching valve 24b (open / close valve) and a second regulator 24c (pressure reducing device). Even with such a configuration, the pressure on the upstream side of the injector 23 can be lowered by the second regulator 24c, and the operating sound of the injector 23 can be made smaller than that during normal power generation.

1, 1A Fuel cell system 10 Fuel cell stack (fuel cell)
21 Hydrogen supply piping (fuel gas supply piping)
21 High-pressure tank (fuel gas storage means)
23 Injector 24, 24A Pressure adjusting means 24a First regulator (first pressure reducing device)
24b Switching valve (open / close valve)
24c 2nd regulator (2nd decompression device, decompression device)
24d bypass pipe

Claims (5)

A fuel cell;
Fuel gas storage means for storing fuel gas;
A fuel gas supply pipe connecting the fuel cell and the fuel gas storage means;
An injector provided in the fuel gas supply pipe;
Pressure adjusting means provided between the fuel gas storage means and the injector;
Control means for controlling the pressure adjusting means;
With
The control means includes
When the required power generation amount is a predetermined value or more, the pressure adjusting means is controlled in the normal power generation mode,
When the required power generation amount is less than a predetermined value, the pressure adjusting means is controlled in a low load power generation mode in which the pressure of the fuel gas supplied to the injector is lower than that in the normal power generation mode. . The pressure adjusting means is
A first pressure reducing device provided between the fuel gas storage means and the injector;
An on-off valve provided between the first pressure reducing device and the injector;
A second pressure reducing device provided to bypass the on-off valve;
With
The fuel cell system according to claim 1, wherein the control means closes the on-off valve in the low load power generation mode. The pressure adjusting means is provided between the fuel gas storage means and the injector, and includes a variable pressure reducing device capable of changing a secondary side pressure,
The said control means controls the said variable pressure-reduction apparatus so that the pressure of the fuel gas supplied to the said injector may become lower than the time of the said normal electric power generation mode at the time of the said low load electric power generation mode. The fuel cell system described. A fuel cell;
Fuel gas storage means for storing fuel gas;
A fuel gas supply pipe connecting the fuel cell and the fuel gas storage means;
An injector provided in the fuel gas supply pipe;
An on-off valve provided between the fuel gas storage means and the injector;
A pressure reducing device that bypasses the on-off valve and lowers the pressure of the fuel gas supplied to the injector than when the on-off valve is opened;
A fuel cell system comprising: A fuel cell;
Fuel gas storage means for storing fuel gas;
A fuel gas supply pipe connecting the fuel cell and the fuel gas storage means;
An injector provided in the fuel gas supply pipe;
Pressure adjusting means provided between the fuel gas storage means and the injector;
Control means for controlling the pressure adjusting means;
With
The control means includes
A determination step of determining whether the required power generation amount is a predetermined value or more;
A pressure reduction step of controlling the pressure adjusting means in a low load power generation mode in which the pressure of the fuel gas supplied to the injector is lower than in a normal power generation mode when it is determined that the required power generation amount is not equal to or greater than a predetermined value;
A control method for a fuel cell system, comprising:

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