JP3583914B2 - Auxiliary power supply for fuel cell - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power supply for auxiliary equipment that supplies electric power to auxiliary equipment necessary for maintaining operation of a fuel cell.
[0002]
[Prior art]
Conventionally, a fuel cell main unit, a storage battery, a fuel supply source, a controller, etc. are provided, and surplus power after supplying power generated by the fuel cell main unit to an external load is stored in the storage battery, and the power generated by the fuel cell main unit is insufficient. In such a case, there is known a fuel cell which supplements electric power from a storage battery and supplies it to an external load.
Such fuel cells are expected to be widely used as power supplies for civil engineering and construction work, home emergency power supplies, and the like.
[0003]
The fuel cell includes an acidic fuel cell and an alkaline fuel cell. The characteristics of the polymer electrolyte fuel cell, which is 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 catalyst electrodes (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]
Then, the hydrogen in the humidified fuel supplied to the anode electrode side is hydrogen-ionized on the catalyst electrode (anode electrode) 02, and the hydrogen ions are converted into H ⁺ .xH ₂ O in the electrolyte 01 with the intervention of water. Move with the water to the cathode electrode side. The transferred hydrogen ions react with oxygen in the oxidizing agent (for example, air) on the catalyst electrode (cathode electrode) 03 and 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.
[0005]
In the polymer ion exchange membrane serving as the electrolyte 01, in order to realize the hydrogen ion permeability as described above, it is necessary to keep the polymer ion exchange membrane always in a sufficiently water-retaining state, for example, The fuel or the oxidizing agent is made to contain saturated steam 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 oxidizing agent to the electrode assembly 06 and maintain the water retaining state of the membrane. Like that. Further, the fuel cell generates heat during operation, and thus needs to be cooled.
[0006]
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 electrode to the remaining fuel gas and discharged out of the fuel cell.
[0007]
FIG. 5 is an explanatory diagram of a fuel cell that generates power 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 gas in the fuel cell body 6 A small amount of unreacted exhaust hydrogen and exhaust air are discharged to the outside of 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 the water to the fuel cell body 6, and the water is circulated for use.
[0008]
[Problems to be solved by the invention]
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 the auxiliary equipment (the electromagnetic valve 4, the fan 7, etc.) to start the fuel cell main body 6, and then to the auxiliary equipment. Is switched from the starting battery to the DC / DC converter for 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, there may be a case where the auxiliary power cannot be provided. 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 an auxiliary power supply for a fuel cell that can be started smoothly without causing a voltage drop of the fuel cell main body 6 or the like.
[0009]
[Means for Solving the Problems]
That is, in order to solve the above-described problem, the invention according to claim 1 starts up without receiving power supply from the outside, and in a fuel cell configured to be able to generate electric power, a part of the electric power generated by the fuel cell is A DC / DC converter for auxiliary equipment, which is a power supply for auxiliary equipment capable of supplying to auxiliary equipment required for independent power generation of the fuel cell, the auxiliary DC / DC converter for converting a voltage of a part of electric power generated by the fuel cell; a starting battery to be charged by the output of the DC / DC converter for auxiliary machinery, the input current limiting mechanism for controlling the initial start of the previous SL fuel cell power from the fuel cell through the DC / DC converter the auxiliary And the following.
An input current limiting function is provided in the DC / DC converter for auxiliary equipment to limit the output from the fuel cell to the auxiliary equipment when the characteristics of the fuel cell are deteriorated 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.
[0010]
According to a second aspect of the present invention, in the power supply for an auxiliary machine of the fuel cell according to the first aspect, the input current limiting mechanism controls electric power passing through the DC / DC converter based on a voltage generated by the fuel cell. It is characterized by doing.
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]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing one embodiment of a fuel cell provided with a power supply for an auxiliary device of a fuel cell according to the present invention, and FIG. 2 is an explanatory diagram explaining a power supply for an auxiliary device of the fuel cell of the present invention. FIG. 3 is a graph showing an example of the relationship between the voltage of the fuel cell body and the input current limit set value from the control device.
[0012]
In FIG. 1, the fuel cell 8 has a case 12 in which a fuel gas cylinder 1 is stored in an upright state. A control device 13 including a not-shown starting battery 25 and a DC / DC converter 23 for auxiliary equipment and the like are stored in the upper part of the rear part of the case 12, and hydrogen in the fuel and air as an oxidant are stored in the middle part. A fuel cell main body 6 that is supplied and generates electricity by performing an electrochemical reaction is housed therein, and a DC / AC inverter 14 and a water reservoir 11 are housed in a lower stage.
[0013]
The hydrogen of the fuel is adjusted from the fuel gas cylinder 1 through a regulator 3 for adjusting the pressure from a high pressure to a low pressure (not shown), a regulator 5 for adjusting the pressure from a low pressure to a supply pressure to the fuel cell body 6, and then via an electromagnetic valve 4. Is supplied to the anode of the fuel cell 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 through 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 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.
[0014]
Hydrogen is supplied from the pipe 9 to the anode of the fuel cell body 6 and water is supplied. Reference numeral 10 denotes a water pump for pumping water from the water reservoir 11 and supplying the water to the fuel cell 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 by the exhaust duct 16 collects in a drain tank 17, is temporarily stored, and is drained outside through a drain pipe 18.
[0015]
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, and a charger 31. A plug 32 connected to a commercial power supply, a line connecting these, and the like, and a voltage detector 22, a DC / DC converter 23 for auxiliary equipment, and a control device 13 are arranged in series. A starting battery 25 is connected in parallel with the accessory DC / DC converter 23 to a line 24 connecting the accessory DC / DC converter 23 and the control device 13.
Reference numeral 33 denotes a DC / DC converter that raises the power generated by the fuel cell body 6 to a DC voltage of 280 V, reference numeral 34 denotes a DC / AC converter that converts a DC voltage of 280 V to AC power of 100 V, and reference numeral 35 denotes a harmonic component generated by the converter. This is a transformer that reduces the DC component and eliminates the DC component.
[0016]
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. 27, a setting signal is sent to the accessory DC / DC converter 23 to limit the power passing through the DC / DC converter 23, thereby reducing the load on the fuel cell body 6 and causing an abnormality due to the overload of the fuel cell body 6. Voltage drop can be prevented.
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 a DC power voltage (24 to 50 V DC) from the fuel cell main body 6 into a predetermined voltage (for example, 14 V DC). In this example, a signal from the control device 13 is used. The chopping duty of the accessory DC / DC converter 23 is variably controlled. When the ON duty is 0%, the passing power becomes 0. By increasing the ON duty, the passing power increases.
[0017]
As shown in FIG. 3, as an example of the setting signal from the control device 13, in the initial stage of starting the fuel cell main body 6, the voltage of the fuel cell main body 6 detected by the voltage detector 22 is 0 to a predetermined a value (for example, In the range up to 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 body 6 is in the range of a to b values, power to the auxiliary equipment is sent from the starting battery 25 and the fuel cell body 6, but as shown by a straight line c, 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 body 6 reaches the value b, all the power is switched to the accessory DC / DC converter 23, and power is supplied to the accessory only from the fuel cell body 6, and the power is supplied in the range of b to d. A predetermined electric power corresponding to the set value e is supplied from the fuel cell body 6 to the auxiliary machine.
Specifically, the ON duty is set so that the output voltage of the DC / DC converter 23 is higher than the rated voltage (24 V) of the starting battery 25 by about 1 to 2 V.
[0018]
It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the appended claims. Further, the target fuel cell is not limited to the solid polymer type.
[0019]
【The invention's effect】
The auxiliary power supply for a fuel cell according to the present invention is provided by providing an input current limiting function to the DC / DC converter for the auxiliary equipment, and by limiting the output from the fuel cell to the auxiliary equipment when the characteristics of the fuel cell deteriorate in the initial stage of startup. Since the load on the fuel cell can be reduced and an abnormal voltage drop of the fuel cell can be prevented, the operation can be continued.
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 25 for auxiliary equipment Start-up battery

Claims (2)

In a fuel cell configured to be able to start and generate power without receiving external power supply, a part of the power generated by the fuel cell can be supplied to an auxiliary machine required for the power generation of the fuel cell alone. A power supply for auxiliary equipment,
An auxiliary DC / DC converter for converting a voltage of a part of the electric power generated by the fuel cell;
A starting battery charged by an output of the auxiliary machine DC / DC converter;
An input current limiting mechanism for controlling power from said fuel cell through the DC / DC converter the auxiliary startup initial pre Symbol fuel cell,
A power supply for an auxiliary machine of a fuel cell, comprising: The auxiliary power supply for a fuel cell according to claim 1, wherein the input current limiting mechanism controls electric power passing through the DC / DC converter based on a voltage generated by the fuel cell.

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