KR100341435B1 - Method and apparatus for preventing a reverse voltage in a fuel cell - Google Patents

Abstract

The present invention relates to an apparatus and method for preventing a reverse voltage of a fuel cell, comprising: a plurality of fuel cells configured to determine whether each fuel cell has generated normal electromotive force and to flow current through the fuel cells connected in series when normal electromotive force occurs; If the normal electromotive force is not generated in a specific fuel cell among a plurality of fuel cells, a plurality of diodes may be bypassed through a diode connected in parallel to the specific fuel cell instead of the specific fuel cell in which no electromotive force is generated. Equipped. Therefore, the burnout of the fuel cell can be prevented, and even if some fuel cells lose electromotive force, the diode is bypassed using a diode, so that only the remaining fuel cell can be operated.

Description

TECHNICAL AND APPARATUS FOR PREVENTING A REVERSE VOLTAGE IN A FUEL CELL}

The present invention relates to an apparatus and method for preventing a reverse voltage of a fuel cell, and in particular, an apparatus for preventing reverse voltage from being applied to a fuel cell by connecting diodes in parallel in parallel to fuel cells connected in series. And to a method.

Typically, a fuel cell is an energy conversion device that converts chemical energy of a fuel into electrical energy directly by a chemical reaction. Unlike conventional batteries, fuel cells are power generation systems that can continue to generate electricity as long as fuel is supplied without the need for recharging.

In the fuel cell, as shown in FIG. 1, an electrolyte and two electrodes are stacked as sandwiches, and electricity is generated when oxygen and hydrogen flow to each electrode, and heat and water are by-products. Is made as.

Various fuels such as natural gas, methanol, and gasoline may be used in the fuel cell, which is reformed into hydrogen using a fuel reformer.

The fuel cell was invented and patented by Bacon (F.T. Bacon) in 1952 since it was invented by W.R. Grove of England in 1839.

In the United States, this patent was retrofitted to Apollo 11 in 1969 and has since been used as a power and drinking water source for spacecraft. The United States began full-fledged development in the 1960s and Japan in the early 1980s, and these two countries are leading the development of fuel cells. In terms of fuel cell technology, Europe is relatively inferior to the US and Japan, and Korea has been promoting the leading technology project (G-7 project) since 1988.

The biggest advantage of the fuel cell is its high energy conversion efficiency and environmental friendliness. Because it converts chemical energy directly into electrical energy, it shows higher efficiency than the existing power generation method that goes through several stages of energy conversion device. In addition, since it emits almost no pollutants such as NOx or SOx, the environmental problem is emerging as a next generation power generation method. On the other hand, it is easy to adjust the size due to the configuration of the fuel cell has the advantage that can be easily installed and used in the city or general homes regardless of the place.

However, since the output voltage of the fuel cell is relatively low, such as several volts, a plurality of fuel cell cells 20 connected in series are used to obtain a higher voltage.

In this case, when some fuel cell cells lose electromotive force due to a problem such as unsatisfactory supply of fuel, some voltages generated by a plurality of fuel cell cells 20 that operate normally may cause a specific fuel cell cell that has lost electromotive force. There was a problem that the application was reversed, causing this particular fuel cell cell to be permanently destroyed.

Meanwhile, in order to prevent the application of such a reverse voltage and to prevent the destruction of the fuel cell 20, a plurality of fuel cell 20 connected in series by having a voltage monitoring unit 23 as shown in FIG. 2. When each voltage is detected and falls below a predetermined voltage, the fuel cell monitoring and controller 25 detects this signal and stops the entire fuel cell system.

However, such a reverse voltage prevention device according to the related art has a disadvantage in that it is complicated and expensive, and at the same time, the entire fuel cell system does not operate even when one fuel cell does not operate.

Accordingly, the present invention has been made to solve the above-described problems, the object of the present invention is to connect the diodes in parallel in parallel to the fuel cell (fuel cell) connected in series, respectively, to prevent from the reverse voltage caused by the electromotive force drop of the fuel cell The present invention provides a fuel cell reverse voltage prevention device and method for protecting a fuel cell and preventing a reverse voltage applied to the fuel cell.

In the present invention for achieving the above object, the apparatus for preventing reverse voltage of a fuel cell determines whether each fuel cell generates a normal electromotive force, and when a normal electromotive force is generated, a plurality of fuels for flowing current through a series of fuel cells connected in series. battery; If the normal electromotive force is not generated in a specific fuel cell among a plurality of fuel cells, a plurality of diodes may be bypassed through a diode connected in parallel to the specific fuel cell instead of the specific fuel cell in which no electromotive force is generated. Include.

In addition, the reverse voltage prevention method of the fuel cell in the present invention for achieving the above object comprises the steps of connecting a plurality of fuel cells in series to generate a high voltage using the fuel cell; Anti-parallel diodes respectively connected to each of the plurality of fuel cells connected in series; Determining whether electromotive force is generated in the plurality of fuel cells; When normal electromotive force is generated in the plurality of fuel cells in the determining step, a current flows through the plurality of fuel cells; If the normal electromotive force is not generated in at least one of the plurality of fuel cells in the determining step, preventing a reverse voltage from being applied to the fuel cell by allowing a current to flow through a diode corresponding to the fuel cell that does not generate normal electromotive force. It includes.

1 is a view showing the principle of a fuel cell,

2 is a diagram illustrating an apparatus for detecting a reverse voltage caused by a decrease in electromotive force of a fuel cell and stopping an operation according to the related art.

3 is a block diagram of an apparatus for preventing reverse voltage of a fuel cell according to the present invention;

4 is a detailed flowchart of a method for preventing reverse voltage of a fuel cell according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

30: a plurality of fuel cells 33: a plurality of diodes

35: load

A: Fuel cell that does not generate electromotive force

B: bypass diode

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment according to the present invention.

Referring to FIG. 3, a block diagram of an apparatus for preventing a reverse voltage of a fuel cell according to the present invention includes a plurality of fuel cells 30, a plurality of diodes 33, and a load 35.

The plurality of fuel cells 30 are connected in series to generate a high voltage by using the fuel cell shown in FIG. 1. When the plurality of fuel cells 30 normally generate electromotive force, the plurality of fuel cells 30 Current flows normally between the 30 and the load 35. On the other hand, when the normal electromotive force is not generated in a specific fuel cell A among the plurality of fuel cells 30, a current is not flowing through the fuel cell A, but a plurality of fuel cells A correspond to the fuel cell A. The current flows between the loads 35 through the bypass diode B of the diodes 33.

The plurality of diodes 33 are connected to the plurality of fuel cells 30 in parallel and in parallel. In the normal case in which all of the plurality of fuel cells 30 normally generate an electromotive force, the plurality of diodes 33 are reversed to the plurality of diodes 33. Since voltage is applied, it cannot conduct and no current flows. At this time, when the electromotive force is not generated in the specific fuel cell A among the plurality of fuel cells 30, current is bypassed through the diode B corresponding to the fuel cell A instead of the fuel cell A. (bypass)

With reference to the flowchart of Figure 4, the reverse voltage prevention method of the fuel cell according to the present invention will be described in detail.

First, in order to generate a high voltage using the individual fuel cells shown in FIG. 1, fuel cells are connected in series (step 41), and a plurality of diodes 33 are connected to each fuel cell in parallel and in parallel. (Step 42).

Next, it is determined whether all of the plurality of fuel cells 30 normally generate electromotive force (step 43).

When all of the plurality of fuel cells 30 normally generate an electromotive force in the determination step 43, since a reverse voltage is applied to the plurality of diodes 33, no current flows through the plurality of fuel cells 30 without conduction. Current flows (step 44).

On the contrary, when the determination step 43 does not generate normal electromotive force in the specific fuel cell A among the plurality of fuel cells 30, a bypass diode corresponding to the specific fuel cell A Allow current to flow through (B) (step 45).

Therefore, a reverse voltage above the forward voltage drop of the bypass diode B is not applied to the specific fuel cell A that does not generate a normal voltage, thereby preventing the fuel cell A from being burned out from the reverse voltage. (Step 46).

Therefore, the present invention prevents burnout of a fuel cell by preventing a reverse voltage applied to a fuel cell that does not generate a normal voltage by connecting diodes in parallel to each of a plurality of fuel cells connected in series. Even if some fuel cells lose electromotive force, they bypass by using diodes, so that only the remaining fuel cells can operate.

Claims (3)

In a fuel cell system in which a plurality of fuel cells are connected in series to generate a high voltage using a fuel cell, A plurality of fuel cells configured to determine whether each of the fuel cells has generated normal electromotive force and to flow current through the fuel cells connected in series when normal electromotive force is generated; If a normal electromotive force is not generated in a specific fuel cell among the plurality of fuel cells, a plurality of currents are bypassed through a diode connected in parallel to the specific fuel cell instead of the specific fuel cell in which the electromotive force is not generated. Reverse voltage prevention device of a fuel cell, characterized in that it comprises a diode. The method of claim 1, wherein the plurality of diodes, The reverse voltage prevention device of a fuel cell, characterized in that the conduction only when no electromotive force is generated in the corresponding fuel cell. In the method for preventing the reverse voltage is applied to the fuel cell, Connecting a plurality of fuel cells in series to generate a high voltage using the fuel cell; Anti-parallel diodes respectively connected to each of the plurality of fuel cells connected in series; Determining whether electromotive force is generated in the plurality of fuel cells; When normal electromotive force is generated in the plurality of fuel cells in the determining step, a current flows through the plurality of fuel cells; If the normal electromotive force is not generated in at least one of the plurality of fuel cells in the determining step, a reverse voltage is applied to the fuel cell by allowing a current to flow through a diode corresponding to the fuel cell that does not generate normal electromotive force. The method of preventing a reverse voltage of a fuel cell comprising the step of preventing.