JPH11176454A - Power source for fuel cell accessory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source for a fuel cell accessory to limit the output from a fuel cell to the accessory, when characteristics of the fuel cell are deteriorated in an initial stage of starting for lowering load on the fuel cell, preventing abnormal voltage reduction of the fuel cell, and increasing the service life of a battery for starting. SOLUTION: This device is a power source for an accessory which feeds a part of power generated by a fuel cell to the accessory necessary for sole power generation of the fuel cell, it is provided with a battery 25 for starting to which part of the power generated by the fuel cell is charged after voltage conversion by a DC/DC converter 23, and an input current limiting mechanism 13 for controlling the power from the fuel cell passing a DC/DC converter 25, and the accessory is connected to be driven by the output of the battery 25 for starting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for auxiliary equipment for supplying power to auxiliary equipment necessary for maintaining operation of a fuel cell.

[0002]

2. Description of the Related Art Conventionally, a fuel cell body, a storage battery, a fuel supply source, a controller and the like are provided, and surplus power after supplying power generated in the fuel cell body to an external load is stored in the storage battery. 2. Description of the Related Art There is known a fuel cell which supplements electric power from a storage battery and supplies it to an external load when generated electric power is insufficient. Such fuel cells have attracted many expectations as power supplies for civil engineering and construction work, home emergency power supplies, and the like.

There are two types of fuel cells: an acidic fuel cell and an alkaline fuel cell. The characteristics of a polymer electrolyte fuel cell, one of the acidic fuel cells, will be described below. As shown in FIG. 4, the polymer electrolyte fuel cell uses a polymer ion-exchange membrane (for example, a fluororesin-based ion-exchange membrane having a sulfonic acid group) for the electrolyte 01, and a catalyst electrode (for example, platinum) on both sides thereof. Etc.) and an electrode assembly 06 including current collectors 02 and 03 and current collectors 04 and 05.

[0004] Hydrogen in the humidified fuel supplied to the anode electrode is hydrogen-ionized on the catalyst electrode (anode electrode) 02, and the hydrogen ions pass through the electrolyte 01 with H ^+. _{As 2} O, it moves together with water to the cathode electrode side. The transferred hydrogen ions react with oxygen in the oxidant (for example, air) on the catalyst electrode (cathode electrode) 03 and the electrons flowing through the external circuit 07 to generate water. The generated water is transported from the cathodes 03 and 05 to the remaining oxidant and discharged out of the fuel cell. At this time, the flow of electrons flowing through the external circuit 07 can be used as DC electric energy.

In order to realize the above-mentioned hydrogen ion permeability in the polymer ion exchange membrane serving as the electrolyte 01, it is necessary to keep the polymer ion exchange membrane in a sufficiently water-retaining state at all times. Yes, for example, the fuel or oxidant is made to contain saturated water vapor corresponding to the vicinity of the operating temperature of the fuel cell (normal temperature to about 100 ° C.), that is, humidified to supply the fuel and the oxidant to the electrode assembly 06 to retain the water of the membrane. I try to keep my condition. In addition, the fuel cell generates heat during operation, and thus needs to be cooled.

On the other hand, in the case of an alkaline fuel cell, hydroxyl ions move in the electrolyte and react with fuel gas (hydrogen gas) on the anode electrode to generate water. The generated water is transported from the anode to the remaining fuel gas and discharged out of the fuel cell.

FIG. 5 is an explanatory view of a fuel cell that generates electricity by supplying hydrogen as fuel and air as an oxidant to a fuel cell body. In FIG. 5, from a fuel gas cylinder 1 filled with hydrogen fuel, a manual stopper 2, a regulator 3 for adjusting pressure from high pressure to low pressure, solenoid valves 4 and 4, a regulator 5 for adjusting pressure from the low pressure to a supply pressure to the fuel cell body. The hydrogen gas supplied to the anode electrode of the fuel cell body 6 via the fuel cell is taken in from the outside of the fuel cell 8 by the fan 7 and sent to the cathode electrode of the fuel cell body 6, and the electrochemical A small amount of unreacted exhaust hydrogen and exhaust air are discharged outside the fuel cell 8 by performing a reaction to generate power. Water is supplied to the anode of the fuel cell body 6 together with hydrogen. Reference numeral 10 denotes a water pump for pumping water from the water reservoir 11 and supplying it to the fuel cell main body 6, and the water is circulated for use.

[0008]

When the fuel cell body 6 is started, first, electric power is sent from a starting battery (not shown) provided in the fuel cell 8 to auxiliary equipment (such as the solenoid valve 4 and the fan 7) to start the fuel cell body 6. Then, the power supply to the auxiliary equipment is switched from the starting battery to the DC / DC converter for the auxiliary equipment (not shown) provided in the fuel cell 8 to start the power supply from the fuel cell main body 6 to the auxiliary equipment. . However, since the temperature of the fuel cell body 6 is low and the power generation capacity is low for a while after the start-up, the power of the auxiliary equipment may not be supplied in some cases. In such a case, the voltage of the fuel cell body 6 decreases. Startup operation cannot be continued. An object of the present invention is to provide a fuel cell
It is an object of the present invention to provide a power supply for an auxiliary device of a fuel cell, which can be started smoothly without causing a voltage drop or the like.

[0009]

In order to solve the above-mentioned problems, a first aspect of the present invention is directed to a fuel cell which is configured to be capable of generating power independently, wherein a part of the power generated by the fuel cell is used as the fuel cell. A power supply for auxiliary equipment capable of supplying to auxiliary equipment necessary for independent power generation, wherein a part of electric power generated by the fuel cell is voltage-converted by a DC / DC converter and then charged; An input current limiting mechanism for controlling electric power from the fuel cell passing through the DC / DC converter, and the auxiliary machine is operably connected to the output of the starting battery. . An input current limiting function is provided in the accessory DC / DC converter to limit the output from the fuel cell to the accessory when the characteristics of the fuel cell deteriorate in the early stage of startup, thereby reducing the load on the fuel cell and causing an abnormality in the fuel cell. Since the voltage drop can be prevented, the operation can be continued.

According to a second aspect of the present invention, in the fuel cell auxiliary power supply according to the first aspect, the input current limiting mechanism is configured to control the DC / DC based on the power generated by the fuel cell.
It is characterized in that the power passing through the converter is controlled. For example, the control device monitors the voltage of the fuel cell, and outputs a setting signal for lowering the current limit value of the DC / DC converter for auxiliary equipment when the voltage drops. The optimum setting can be performed by outputting a setting signal from the control device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of a fuel cell provided with a power supply for auxiliary equipment of a fuel cell according to the present invention, and FIG. 2 is an explanatory view for explaining a power supply for auxiliary equipment of a fuel cell according to the present invention. FIG. 3 is a graph showing an example of the relationship between the voltage of the fuel cell main body and the input current limit set value from the control device.

In FIG. 1, a fuel cell 8 includes a case 12
The fuel gas cylinder 1 is stored in an upright state. A control device 1 having a start-up battery 25 and an auxiliary DC / DC converter 23 (not shown) is provided in an upper portion of a rear portion of the case 12.
3 and the like, a fuel cell body 6 for generating electricity by supplying hydrogen as fuel and air as an oxidant and causing an electrochemical reaction is accommodated in a middle stage, and a DC / AC inverter 14 in a lower stage. And a basin 11 are housed.

The fuel hydrogen is pressure-adjusted from a fuel gas cylinder 1 through a regulator 3 (not shown) from a high pressure to a low pressure, and a pressure regulator 5 from a low pressure to a supply pressure to the fuel cell body 6. 4, is supplied to the anode of the fuel cell main body 6. The hydrogen gas supplied to the anode of the fuel cell body 6 is taken into the case 12 from the outside of the case 12 via the reaction air intake 15 by the fan 7, and the air and fuel sent to the cathode of the fuel cell body 6 The electrochemical reaction is performed in the battery main body 6 to generate power, and a small amount of unreacted exhaust hydrogen and exhaust air that are not reacted are discharged to the outside of the case 12.

Hydrogen is supplied to the anode electrode of the fuel cell main body 6 from the pipe 9 and water is supplied. Reference numeral 10 denotes a water pump for pumping water from the water reservoir 11 and supplying it to the fuel cell main body 6, and the water is circulated for use. Reference numeral 16 denotes an exhaust duct for discharging exhaust air from the fuel cell main body 6 to the outside of the case 12. The water separated in the exhaust duct 16 collects in the drain tank 17,
Once stored, it is drained to the outside via a drain pipe 18.

In FIG. 2, a power supply 21 for auxiliary equipment of a fuel cell according to the present invention includes a voltage detector 22, a DC / DC converter 23 for auxiliary equipment, a control device 13, a starting battery 25, a charging circuit 30 for the battery 25, It has a charger 31, a plug 32 connected to a commercial power supply, and a line connecting these. The voltage detector 22, the accessory DC / DC converter 23, and the controller 13 are arranged in series, and the accessory DC / DC converter 23 is connected to a line 24 connecting the accessory DC / DC converter 23 and the controller 13. A starting battery 25 is connected in parallel with the DC converter 23. Reference numeral 33 denotes D for raising the electric power generated by the fuel cell body 6 to a DC voltage of 280 V.
C / DC converter, 34 converts 280V DC voltage to 10
DC / AC converter for converting to 0 V AC power, 35
Is a transformer that reduces harmonic components generated in the converter and eliminates DC components.

For example, when the characteristics of the fuel cell main body 6 are deteriorated in the early stage of startup, the voltage is detected by the voltage detector 22 for detecting the voltage of the fuel cell main body 6, and a signal is sent to the control device 13 via the line 26. The setting signal is sent from the control device 13 via the line 27 to the DC / DC converter 23 for auxiliary equipment.
To limit the power passing through the DC / DC converter 23 to reduce the load on the fuel cell body 6 and prevent an abnormal voltage drop due to the overload of the fuel cell body 6. The starting battery 25 is, for example, a Ni-Cd secondary battery (12V-40Ah) using a nickel electrode for the positive electrode and a cadmium electrode for the negative electrode. The accessory DC / DC converter 23 converts the DC power voltage (24 to 50 V DC) from the fuel cell main body 6 to a predetermined voltage (for example, DC14).
V), and in this example, the chopping duty of the accessory DC / DC converter 23 is variably controlled by a signal from the control device 13. When the ON duty is 0%, the passing power becomes 0. By increasing the ON duty, the passing power increases.

FIG. 3 shows an example of a setting signal from the control device 13, as shown in FIG.
When the voltage of the fuel cell body 6 detected by the voltage detector 22 ranges from 0 to a predetermined value a (for example, 24 V), the ON duty of the DC / DC converter 23 is 0%.
, And all power to the auxiliary equipment is sent from the starting battery 25. When the voltage of the fuel cell main body 6 is in the range of a to b values, the power to the auxiliary equipment is sent from the starting battery 25 and the fuel cell main body 6, but as shown by the straight line c, the electric power from the fuel cell main body 6 The ON duty of the DC / DC converter 23 is increased so that the power of the DC / DC converter 23 is increased in proportion to the voltage. Then, when the voltage of the fuel cell main body 6 reaches the value b, all are switched to the accessory DC / DC converter 23, and power is supplied to the auxiliary machine only from the fuel cell main body 6, and b to
The predetermined electric power corresponding to the set value e is supplied from the fuel cell main body 6 to the auxiliary machine in the range of the d value. Specifically, the output voltage of the DC / DC converter 23 corresponds to the rated voltage (2
The ON duty is set to be higher by about 1 to 2 V than 4 V).

Since the present invention is not limited to the above embodiment, various modifications can be made without departing from the spirit of the present invention. The target fuel cell is not limited to the polymer electrolyte fuel cell.

[0019]

The power supply for the auxiliary equipment of the fuel cell according to the present invention is provided with an input current limiting function in the DC / DC converter for the auxiliary equipment, so that the output from the fuel cell to the auxiliary equipment when the characteristic of the fuel cell is deteriorated in the initial stage of startup. , The load on the fuel cell can be reduced, and abnormal voltage drop of the fuel cell can be prevented, so that operation can be continued. The starting battery is charged by the output of the DC / DC converter for auxiliary equipment, and the DC / DC converter for auxiliary equipment and the starting battery are connected in parallel and the output of the fuel cell is not directly input to the starting battery. The life of the battery can be extended. When the current limit value is set from the control device, the control device monitors the voltage of the fuel cell and outputs a setting signal for lowering the current limit value of the auxiliary DC / DC converter when the voltage drops. Optimum settings can be made.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a fuel cell provided with a power supply for auxiliary equipment of a fuel cell according to the present invention.

FIG. 2 is an explanatory diagram illustrating a power supply for auxiliary equipment of a fuel cell according to the present invention.

FIG. 3 is a graph showing an example of a relationship between a voltage of a fuel cell main body and an input current limit set value from a control device.

FIG. 4 is an explanatory view showing characteristics of a polymer electrolyte fuel cell.

FIG. 5 is an explanatory diagram of a fuel cell that generates electricity by supplying hydrogen and air.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas cylinder 4 Solenoid valve 6 Fuel cell main body 7 Fan 8 Fuel cell 13 Control device 21 Power supply for auxiliary equipment of fuel cell 22 Voltage detector 23 DC / DC converter for auxiliary equipment 25 Starting battery

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Nishizawa 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. An auxiliary power supply for a fuel cell configured to be capable of generating power alone by enabling a part of the power generated by the fuel cell to be supplied to the auxiliary equipment required for power generation of the fuel cell alone. Some of the power generated by the fuel cell is DC
A starting battery that is charged after voltage conversion by a DC / DC converter, and an input current limiting mechanism that controls power from the fuel cell passing through the DC / DC converter,
And an auxiliary power supply for the fuel cell, wherein the auxiliary equipment is drivably connected to the output of the starting battery. 2. The power supply for an auxiliary machine of a fuel cell according to claim 1, wherein said input current limiting mechanism controls electric power passing through said DC / DC converter based on electric power generated by said fuel cell.