JP2819154B2 - Operating method of hybrid fuel cell - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method of operating a hybrid fuel cell provided with a storage battery, and more particularly, to prevent the function of the fuel cell main body from deteriorating and the deep discharge of the storage battery, The present invention relates to a method for operating a hybrid fuel cell that facilitates restart.

[Prior Art] A fuel cell reacts hydrogen with air (oxygen) to generate water and electricity. When such a fuel cell is connected to a load for operation, a storage battery may be provided as an auxiliary power supply at the time of starting or the like, and the storage battery may be charged by the fuel cell.

In such a hybrid fuel cell, in the case of overload operation, power is supplied from both the fuel cell and the storage battery, so that the load on the fuel cell increases as the storage amount of the storage battery decreases, and eventually the design A large current larger than the value is output from the fuel cell. If such a state continues for a long time, the fuel cell generates excessive heat, scatters the electrolyte and deteriorates the performance, and the storage battery also deeply discharges, thereby shortening the life of the entire system. .

Further, even if a system for stopping the operation by detecting the above-described abnormality is provided, there is a problem that restarting after the occurrence of the above situation is extremely troublesome.

[Problems to be solved by the invention]

An object of the present invention is to provide a method of operating a hybrid fuel cell that prevents deterioration of the function of a fuel cell main body and deep discharge of a storage battery and facilitates restarting after an abnormal stop.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a fuel cell that generates power by reacting hydrogen and air, and a storage battery provided in the fuel cell. In operation of a hybrid fuel cell in which the storage battery can be charged by the fuel cell, a terminal of the storage battery is provided. A circuit for detecting a voltage and shutting off a circuit connecting the fuel cell and the storage battery to an external load when the detected terminal voltage is equal to or lower than a preset allowable lower limit voltage.

Hereinafter, the operation method of the present invention will be described with reference to the embodiment shown in the drawings.

FIG. 1 schematically shows a hybrid fuel cell in which the operating method of the present invention is carried out.

1 is a reformer for generating hydrogen, 2 is a fuel cell for generating electricity by reacting hydrogen and air, 3 is a storage battery provided so as to be rechargeable with the fuel cell 2, and 4 is a battery between the fuel cell 2 and the storage battery 3. This is the load connected to both batteries.

The reformer 1 has an evaporator 5 for vaporizing a liquid raw material and a reaction layer 6 for reacting the vaporized raw material gas, and has two types of burners 7m and 7h below it for heating. In this embodiment, a burner 7m using methanol as fuel and a burner 7h using surplus hydrogen as fuel are provided as a burner, but of course, only one type may be used. A blower 11 for supplying air is connected to a lower portion of the reactor.

Reference numeral 8 denotes a fuel tank that stores fuel (methanol) for fuel. Fuel is supplied from the fuel tank 8 to the burner 7m by a supply pump 9 via a valve 10, and is burned by air supplied from a blower 11 to become a heated gas. The heating gas heats the evaporator 5 and the reaction layer 6. On the other hand, reference numeral 12 denotes a raw material tank storing a liquid raw material for reaction (a mixed liquid of methanol and water). The liquid raw material is supplied to the evaporator 5 via the valve 14 by the supply pump 13, is vaporized in the evaporator 5, and reacts in the reaction layer 6 to be converted into a reformed gas mainly composed of hydrogen.

The reformed gas mainly composed of hydrogen generated in the reaction layer 6 is supplied to the supply pipe 15.
Is supplied to the fuel cell 2 through the storage tank 16 and the valve 17. The storage tank 16 temporarily stores the reformed gas,
A predetermined amount is supplied to the fuel cell 2. Excess reformed gas is returned to the burner 7h via the relief valve 18 and / or the bypass valve 19, and is consumed for combustion. Also this burner 7h
The excess hydrogen gas exhausted without being reacted in the fuel cell 2 is also supplied through the reclaimer 20 and the valve 21.

In the fuel cell 2, the air to be reacted with the hydrogen is:
The air is supplied from a blower 22 through a valve 23. A four-way valve 24 is connected to the upstream side of the blower 22 so that either low-temperature air in the atmosphere or high-temperature air in the reformer 1 is appropriately selected and introduced. Excess air not used for the reaction in the fuel cell 2 is discharged to the outside air via the valve 25.

The fuel cell 2 is connected so as to supply the generated power to an external load 4. The storage battery 3 is connected in parallel as an auxiliary power supply and the storage battery 3 is charged. An auxiliary device 26 for the system is connected to the fuel cell 2 and the storage battery 3. The auxiliary device 26 is not limited to the case where a special device is provided as shown in the figure, but may be a drive unit for an internal load such as the pump 9 and the valve 10 provided in the system. Reference numeral 30 denotes a manual load switch for turning on and off the current to the load 4, and reference numeral 31 denotes a protection switch that is turned off when an abnormality occurs in the fuel cell 2 and / or the storage battery 3. Further current sensor 28 in the electric circuit for detecting the output current I _C of the fuel cell 2, the storage battery 3
Such as a voltage sensor 27 for detecting the terminal voltage V _B is connected.

Reference numeral 32 denotes a control unit including a microcomputer having a storage unit, a calculation unit, and the like, and outputs a rotation speed control signal to the supply pump 13 and the blower 22 for the liquid material. The control unit 32 outputs a control signal to the other pump 9, the blower 11, the valves 10, 14, 17, 19, 21, 23, 24, 25, the switch 31, and the like. The control unit 32
The detection signal of the terminal voltage of the storage battery, the output current of the fuel cell from the voltage sensor 27 and the current sensor 28, the temperature sensor
Detection signals such as reaction layer temperature, burner temperature, fuel cell reaction temperature, and ambient temperature are input from 41, 42, 43, and 44.

In the storage unit of the control unit 32, a lower limit voltage VB _{/ min} of a limit for preventing the storage battery 3 from being deeply discharged and a second lower limit voltage VB _{/ min '} larger than this are preset. Have been. The former first lower limit voltage VB _{/ min} may be, for example, 10.0 to 1 if the storage battery is a normal 12 volt lead storage battery.
0.5 volt is set. Also, in this embodiment,
Upper design value I of the output current I _C of the fuel cell 2 in the storage unit
_{C / max} is set in advance. This upper limit design value I _{C / max}
As the threshold value, a limit value is selected at which the function of the fuel cell body is not destroyed early due to excessive heat generation.

In the above-described operation of the hybrid fuel cell, since the load 4 is excessive, electric power is continuously supplied from both the fuel cell 2 and the storage battery 3, and as a result, as shown in FIG. storage amount) is decreased to the lower limit voltage V _{B / min,} also the fuel cell 2 and in a state of outputting a large current I _C to account for the decreased ability of the battery 3.

The terminal voltage V _B of the battery 3 which is a voltage sensor 27 has detected is compared with the lower limit voltage V _{B / min} was set in the storage unit in the arithmetic unit of the control unit 32, it is not more than the lower limit voltage V _{B / min,} The control unit 32 outputs an off signal to the protection switch 31 to cut off the circuit for the external load 4. Blockade of the circuit for the load 4, the load to the fuel cell 2 is to become the only battery 3, the output current I _C decreases, charging is performed with respect to the battery 3. Therefore the terminal voltage V _B of the battery 3 increases again. Thus, the terminal voltage V _B of the storage battery 3
Rises again and exceeds the second lower limit voltage VB _{/ min '} , the control unit 32 turns on the protection switch 31 again, and the load 4
Connect the circuit for and return to normal.

As described above, since the storage amount of the storage battery 3 increases, a deep discharge situation does not occur. Further, since the output current of the fuel cell 2 is low, there is no excess heat generation, no scattering of the electrolyte solution, and the like, so that the function of the fuel cell main body does not deteriorate. As described above, since both the storage battery and the fuel cell main body maintain their original functions, there is no problem when the hybrid fuel cell system is restarted, and a smooth start is guaranteed.

Further, in this embodiment, regardless of the terminal voltage V _B, the output current of the fuel cell 2 by the current sensor 28 detects
When I _C exceeds a predetermined upper limit design value I _{C / max} ,
A signal indicating a decrease in the number of revolutions is output to the fuel pump 13 and / or the blower 22 so that the supply amounts of hydrogen and / or air to the fuel cell 2 are reduced. Thereby, the fuel cell 2
Since the output current I _C of the drops, is also prevented splashing of the electrolyte with heat generation due to excessive current can be prevented. In addition, by enabling operation with such a low current, it is possible to reduce the size of auxiliary equipment such as a cooling fan and to reduce power loss due to these auxiliary equipment in order to prevent excessive heat generation. .

〔The invention's effect〕

As described above, in the operation method of the hybrid fuel cell according to the present invention, the terminal voltage of the storage battery is detected, and when the detected terminal voltage is equal to or lower than the preset allowable lower limit voltage, the fuel cell and the storage battery are connected to an external load. Since the current circuit is cut off, it is possible to prevent the function of the fuel cell main body from deteriorating and the deep discharge of the storage battery. In addition, since the functions of the fuel cell main body and the storage battery do not deteriorate, restart after an abnormal stop can be performed smoothly.

[Brief description of the drawings]

Schematic diagram of a hybrid fuel cell Figure 1 is carrying out the operating method of the present invention, Figure 2 is the charging current I _B and the terminal voltage of the battery
It is a diagram showing a relationship between V _B. 1 ... reformer, 2 ... fuel cell, 3 ... storage battery, 4 ...
... Load, 27 ... Voltage sensor, 31 ... Protection switch, 32 ...
... Control unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-138854 (JP, A) JP-A-53-37028 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 8/00-8/24

Claims (1)

(57) [Claims] 1. A hybrid fuel cell in which a storage battery is provided in addition to a fuel cell that generates power by reacting hydrogen and air, and a terminal voltage of the storage battery is detected during operation of a hybrid fuel cell in which the storage battery can be charged by the fuel cell. When the detected terminal voltage is equal to or lower than a preset allowable lower limit voltage, a method of operating a hybrid fuel cell that shuts off a circuit connecting the fuel cell and the storage battery to an external load.