JPH07302606A - Starting method for hydrogen storage tank built-in fuel cell system - Google Patents

Abstract

PURPOSE:To prevent an operation impossible phenomenon caused by the shortage of power for an internal load by controlling supply power when detected hydrogen gas pressure is lower than reference gas-pressure and is higher than set pressure. CONSTITUTION:When a fuel cell 1 starts load temperature rising, a controller 9 reads out a gas pressure value in a hydrogen storage tank 2 through a hydrogen gas pressure sensor 3 and refers it to a hydrogen gas pressure upper limit value PH which is previously set in an operation control program. When the hydrogen gas pressure is equal to the upper limit value or higher, the controller 9 sets an internal set value in LH and increases internal load current. When the hydrogen pressure is less than the upper limit PH, the controller 9 reads out a hydrogen gas pressure value in the hydrogen storage tank through the sensor 3, and refers it to a hydrogen gas pressure lower limit value PL. When the hydrogen gas pressure is less than the lower limit value PL, the controller decrease the internal load current, keeps this state for a specified time, and waits rising of the temperature in the hydrogen storage tank, then after a specified time elapsed, measures the gas pressure again, and conducts the same operation as the above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a fuel cell system using a hydrogen storage tank using a hydrogen storage alloy as a hydrogen supply source.

[0002]

2. Description of the Related Art Conventionally, as a power source using a fuel cell, a stationary type and a portable type are known. In the case of a stationary power supply, the load heating heater can be heated to heat the battery by supplying power from an external power supply, but in the case of a portable power supply with a relatively small output such as a mobile power supply, Since it is not possible to expect power supply from an external power source unlike the stationary power source, the heater is heated to raise the temperature of the battery by utilizing a part of the power generated by the fuel cell. As such a heater heating type fuel cell system, as shown in FIG. 6, a fuel cell 51, a control device 54, an internal load (heater 1 to heater 1
3) A system including 53 and a DC / DC converter 56 is known. This system controls the operation of the heater and gradually raises the temperature of the fuel cell while monitoring the cell voltage and the cell current. To do.

By the way, recently, a hydrogen storage tank in which hydrogen is stored in a hydrogen storage alloy has come to be used as a fuel supply source of a portable fuel cell system. A portable fuel cell system using such a hydrogen storage tank has a higher hydrogen storage efficiency per unit capacity than a compression-pressurized hydrogen storage tank, so compared to the case of using a compression-pressurized tank. Therefore, the system can be made compact, which is extremely useful.

[0004]

However, since the release of hydrogen from the hydrogen storage alloy is an endothermic reaction, when the amount of heat corresponding to the endothermic amount of the release of hydrogen is not sufficiently supplied from the outside, it is gradually increased. There is a problem that the temperature of the hydrogen storage tank decreases and the hydrogen supply capacity decreases. Therefore,
In a fuel cell system incorporating a hydrogen storage tank, when the outside air temperature is low, the fuel cell main body is heated to a suitable operating temperature, and the hydrogen storage tank is also heated so that the hydrogen storage tank can It must be in a state where hydrogen necessary for the reaction can be sufficiently supplied. However, since the temperature of the fuel cell main body is low at the time of starting the cell, the power generation capacity is small and the temperature of the hydrogen storage tank is also low, so that hydrogen is not sufficiently supplied from the hydrogen storage tank. Therefore, in order to heat the battery body and hydrogen storage tank,
When the internal heater of the system is activated, power is not generated to cover the load, and a vicious cycle between heating and power generation occurs, rendering the battery inoperable and shifting the battery to a steady operating state forever. There was a problem that I could not.

In order to solve the above problems, the present invention is a fuel cell system incorporating a hydrogen storage tank capable of starting a cell while applying an optimum load according to the hydrogen supply capacity of the hydrogen storage tank. The purpose is to provide a method of starting.

[0006]

A method for starting a fuel cell system according to the present invention uses a generated power obtained by supplying hydrogen from a hydrogen storage tank for storing hydrogen which uses a hydrogen storage alloy. To heat up the temperature raising heater, which is an internal load,
In the fuel cell system that heats the fuel cell main body and the hydrogen storage tank by the heat of the heater, a hydrogen gas pressure detection step of detecting the pressure of the hydrogen gas supplied from the hydrogen storage tank at regular intervals; Hydrogen gas pressure determination step of determining whether the hydrogen gas pressure detected in the gas pressure detection step is lower than a predetermined reference gas pressure or higher than a predetermined reference gas pressure, and the hydrogen gas pressure detected in the hydrogen gas pressure detection step. However, when it is lower than a predetermined reference gas pressure, a current smaller than a predetermined current is supplied to the temperature raising heater,
When the hydrogen gas pressure is equal to or higher than a predetermined pressure, the power supply control step of supplying a current larger than the predetermined current to the temperature raising heater is repeated to shift the fuel cell main body to a steady operation state. Characterize.

[0007]

According to the above construction, in the hydrogen gas pressure detecting step, the pressure of the hydrogen gas supplied from the hydrogen storage tank is detected at regular intervals. In the hydrogen gas pressure determination step, it is determined whether the hydrogen gas pressure detected in the hydrogen gas pressure detection step is lower than a predetermined reference gas pressure or higher than a predetermined reference gas pressure. Then, in the power supply control step, when the hydrogen gas pressure detected in the hydrogen gas pressure detection step exceeds a predetermined reference gas pressure, a current smaller than a predetermined current is supplied to the temperature raising heater, while the hydrogen gas When the gas pressure is equal to or higher than the predetermined pressure, a current larger than the predetermined current is supplied to the temperature raising heater. While repeating such a series of steps, the temperature of the fuel cell main body is gradually raised to shift to the steady operation.

With such a structure, when the outside air temperature is low, the phenomenon that occurs in the conventional internal load control system, that is, the pressure of the hydrogen gas supplied from the hydrogen storage tank is the hydrogen required at the initial stage of startup. It is possible to prevent a phenomenon in which the amount of power generated by the fuel cell is significantly reduced due to a shortage of hydrogen gas because the gas pressure is lower than the gas pressure, and the power cannot be supplied to the internal load, resulting in inoperability.

[0009]

FIG. 1 is a schematic configuration diagram of a portable fuel cell system used for realizing the starting method of the present invention. In FIG. 1, reference numeral 1 is a fuel cell main body that generates electricity using hydrogen gas and oxygen gas (air). 2 is a hydrogen storage tank for supplying fuel gas to the fuel cell 1, 3 is a hydrogen gas pressure sensor for measuring the pressure of hydrogen gas supplied from the hydrogen storage tank, and 4 is a battery for measuring the temperature of the fuel cell body. It is a temperature sensor. Reference numerals 5, 6 and 7 are internal loads (heaters) for raising the temperature of the fuel cell 1, and 8 is a blower for blowing the heat of the internal loads (heater) to the fuel cell main body. Further, 9 controls the internal loads 5, 6, and 7 based on the gas pressure information from the hydrogen gas pressure sensor 3, and the temperature of the fuel cell is a predetermined temperature based on the temperature information from the temperature sensor 4. The control unit controls to stop the temperature rise of the load and to start the power supply to the external load when the temperature reaches.

The hydrogen storage tank 2 of the fuel cell system constituted by such members is located at the lee side of the blower 8 so that it can be heated by the air heated by the internal load (heater) and the fuel cell body. It is located. Therefore, when the battery is started up, the heat generated by the internal load and the heat generated by the fuel cell are gradually heated to gradually increase the hydrogen supply capacity. The load control circuit composed of the internal loads 5, 6, and 7 and the control unit 9 may be a switching circuit using a thyristor or the like to adjust the switch-on time to adjust the internal load. it can.

Next, the start-up operation of the portable fuel cell system configured as described above will be described with reference to FIGS.
This will be specifically described. Here, FIG. 2 is a sequence diagram showing a startup main sequence, and FIG. 3 is a sequence diagram showing a sub-sequence of the load temperature increase start step in FIG. The startup main sequence will be described with reference to FIG. First, the hydrogen supply valve (not shown) of the hydrogen storage tank 2 is opened to supply hydrogen gas to the fuel cell body 1 (S100), and the load temperature rise of the fuel cell is started (S200). Next, if the temperature of the fuel cell becomes higher than T _C (S300), output to an external load is enabled (S400). In this example, T _C was set to 80 ° C.

Next, the load temperature increase start step in FIG. 2 will be described with reference to FIG. Step S
When the load temperature rise of the fuel cell 1 is started in 201, the control unit 9 reads the hydrogen gas pressure value of the hydrogen storage tank via the hydrogen gas pressure sensor 3, and the hydrogen gas pressure determined in advance in the operation control program is read. Refer to the upper limit value P _H (step S2)
02). When the hydrogen gas pressure is equal to or higher than the hydrogen gas pressure upper limit value P _H , the internal load set value is set to L _H to increase the internal load current (step S203). On the other hand, when the hydrogen gas pressure is less than the hydrogen gas pressure upper limit value P _{H, the} hydrogen gas pressure value in the hydrogen storage tank is read via the hydrogen gas pressure sensor 3 as in the previous case, and is preset in the operation control program. The hydrogen gas pressure lower limit value P _L is referred to. If the hydrogen gas pressure is less than the hydrogen gas pressure lower limit value P _L , the internal load setting is set to L _L to reduce the internal load current (step S20).
5) This state is maintained for a certain period of time (step S20
6) Wait for the temperature of the hydrogen storage tank to rise. After the elapse of a certain time, the step returns to step S202, the hydrogen gas pressure is measured again, and the above operation is performed.

While the above steps are repeated, the temperature of the hydrogen storage tank (also for the battery) gradually rises and the hydrogen gas pressure in the hydrogen storage tank exceeds the lower limit value P _L (NO in step S204). When the hydrogen gas pressure exceeds the lower limit value P _L , the supply of hydrogen gas is no longer a factor limiting the amount of power generation of the fuel cell, so monitoring of the hydrogen gas pressure is unnecessary. Therefore, the operation proceeds to step S207. In step S207, the control unit 9 determines whether or not the battery temperature is equal to or higher than the temperature T _C that enables steady operation, and if it is equal to or higher than T _C , the start operation is ended. On the other hand, if the cell temperature is lower than T _C , the operation returns to step S202, and while controlling the internal load until the hydrogen gas pressure exceeds the lower limit value P _L again, the fuel cell main body and the hydrogen storage The tank is heated and waits until the hydrogen gas pressure exceeds the lower limit value P _L.

When the hydrogen gas pressure is less than the upper limit value P _{H in} step S202 (step S202, N
O), immediately shifts to the operation of determining whether or not the hydrogen gas pressure is the lower limit value P _L (step S204). Step S20
If YES in 2 and the internal load current is increased in step S203, the fuel cell main body needs more hydrogen gas to cover the load current. However, when the temperature of the hydrogen storage tank is still below the predetermined temperature, the supply of hydrogen gas from the hydrogen storage tank cannot keep up. Therefore, the hydrogen gas pressure decreases again, and the operation proceeds in the YES direction of step S204.

Here, the hydrogen gas pressure upper limit value P_H,hydrogen
Gas pressure lower limit P_L, And battery temperature T _CExplain about
It Hydrogen gas pressure upper limit P_HThe hydrogen from the hydrogen storage tank
Hydrogen storage tank when gas can be released stably
It means the gas pressure of ku. Also, the hydrogen gas pressure lower limit value P_LIs
Internal load setting value is L_HIf the power consumption and the combustion
To generate enough power to cover the internal load of the battery itself
To supply the hydrogen gas required by the fuel cell body
It means the gas pressure in the hydrogen storage tank. This P_H, P
_LIs not a fixed value but used for hydrogen storage tanks
A value that varies depending on the type of hydrogen storage alloy, packing density, etc.
is there. Therefore, in this system, the operator controls the control unit 9
Against P in advance_H, P_LTo be able to set
There is. Note that P_H, P_LCan have the same value
In this case, the hydrogen required for steady operation of the fuel cell
The gas pressure value of the hydrogen storage tank that can supply the gas amount,
Is preferably a function of the gas pressure.

The cell temperature T _C is the cell temperature (normally 80 ° C. to 120 ° C.) at which the fuel cell system can fully exhibit its power generation capacity and supply electric power to an external load.
This T _C also changes to some extent depending on the type of fuel cell. Therefore, in this system, this T _C is also preset by the operator in the control unit 9. In Figure 4,
The relationship between the gas pressure of the hydrogen storage tank and the load current of the fuel cell main body when the outside air temperature is low is schematically illustrated. That is, at the beginning of battery activation, the gas pressure in the hydrogen storage tank is above the lower limit value P _L , but if the amount of heat supplied from the outside air is insufficient as compared with the amount of heat lost during hydrogen release, The release lowers the temperature of the hydrogen storage tank,
Along with this, the amount of hydrogen gas released decreases, so the hydrogen gas pressure decreases. In this case, as described with reference to the flowchart of FIG. 3, the power supply to the internal heater is suppressed, and the consumption amount of hydrogen gas is suppressed to such an extent that the hydrogen storage tank can supply, so that the battery operating state is maintained. . In other words, at the beginning of startup, the fuel cell system is operated with the load on the internal heater being minimized, and the heating of the fuel cell is awaited mainly due to self-heating. When the low-level start-up operation is performed in this manner, the temperature of the fuel cell main body gradually rises, and the temperature of the hydrogen storage tank below it gradually rises. Therefore, the hydrogen supply capacity from the hydrogen storage tank increases, and in parallel with this, the power generation capacity of the fuel cell main body also increases, so that it is possible to accelerate the supply of electric power to the internal heater. As described above, according to the method of the present invention, the power generation capacity of the fuel cell system can be sequentially increased, and as a result, the fuel cell system can be transitioned to the steady operation state without difficulty. [Other Matters] In the above embodiment, step S20 in FIG.
If 7 is YES, it means that the startup has ended, but step S2
Instead of 07, it may be connected to # 710 in the known battery start-up flowchart as shown in FIG. 5, for example. This makes it possible to start the battery more reasonably and quickly.

[0017]

According to the method of starting the fuel cell system of the present invention, the fuel cell system cannot be started even in a situation where hydrogen gas is not sufficiently supplied from the hydrogen storage tank because the outside air temperature is low. There is no. Therefore, the hydrogen storage tank using the hydrogen storage alloy can be used as the fuel supply source of the portable fuel cell, so that the portable fuel cell system can be further downsized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a portable fuel cell power source used for realizing a starting method of the present invention.

FIG. 2 is a sequence diagram showing a startup main sequence.

FIG. 3 is a sequence diagram showing a sub-sequence of a load temperature rising start step in FIG.

FIG. 4 is a schematic diagram showing the relationship between the gas pressure of the hydrogen storage tank and the load current of the fuel cell main body when the outside air temperature is low.

FIG. 5 is a sequence diagram showing a startup operation of a known portable fuel cell power source.

FIG. 6 is a schematic configuration diagram of a conventional portable fuel cell power source.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masashi Fujita 2-5-5 Keihan Hondori, Moriguchi-shi Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A hydrogen storage tank using a hydrogen storage alloy for hydrogen storage is supplied with hydrogen to generate electric power, and the generated electric power is used to heat a heating heater which is an internal load.
In the fuel cell system for heating the fuel cell main body and the hydrogen storage tank by the heat of the heater, the pressure of the hydrogen gas supplied from the hydrogen storage tank is
Hydrogen gas pressure detection step to detect at regular intervals, the hydrogen gas pressure detected in the hydrogen gas pressure detection step,
Below a predetermined reference gas pressure, a hydrogen gas pressure determination step of determining whether the predetermined reference gas pressure or more, the hydrogen gas pressure detected in the hydrogen gas pressure detection step,
When the hydrogen gas pressure is lower than a predetermined reference gas pressure, a current smaller than a predetermined current is supplied to the temperature raising heater, and when the hydrogen gas pressure is equal to or higher than a predetermined pressure, the temperature rising heater is higher than the predetermined current. A method for starting a fuel cell system incorporating a hydrogen storage tank, characterized in that the step of controlling the power supply for supplying an electric current is repeated to shift the fuel cell main body to a steady operation state.