JP4310988B2 - Fuel cell hydrogen deficiency prevention circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen deficiency prevention circuit for a fuel cell mounted on a vehicle.
[0002]
[Prior art]
Fuel cells are attracting attention as a clean power generation. A fuel cell is a device that extracts hydrogen by reacting hydrogen with oxygen. That means
H ₂ + (1/2) O ₂ → H ₂ O + electric energy (electric power) (1)
Power is taken out by the reaction.
[0003]
A cell voltage equalizing apparatus that equalizes a cell voltage or a module voltage without wasting charge energy of a battery of an assembled battery is known (Patent Document 1).
[0004]
A conventional fuel cell will be described with reference to FIG. FIG. 3 shows an example in which three cells are connected in series for simplicity. A voltage of about 0.6 to 1.2 V is generated from one cell. Therefore, when it is normally mounted on a vehicle, 100 to 200 cells are connected in series and used.
[0005]
In the figure, 11a to 11d are carbon separators (collecting electrodes). Solid electrolyte membranes (PEM) 13a to 13c having catalyst membranes 12 formed on both surfaces are disposed at intermediate positions between the carbon separators 11a to 11d facing each other. One cell is constituted by an opposing carbon separator and a solid electrolyte membrane provided at an intermediate position between the opposing carbon separators.
[0006]
Hydrogen is introduced along the horizontal direction from the right side of the solid electrolyte membranes (PEM) 13a to 13c of one cell, and oxygen is introduced along the vertical direction from the left side of the solid electrolyte membranes (PEM) 13a to 13c. Is done. Therefore, a plurality of grooves are formed on the surfaces of the carbon separators 11a to 11d facing the left side of the solid electrolyte membranes (PEM) 13a to 13c along the horizontal direction, and the right side of the solid electrolyte membranes (PEM) 13a to 13c. A plurality of grooves are formed on the surfaces of the carbon separators 11a to 11d facing the surface so as to extend along the vertical direction.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-339865
[Problems to be solved by the invention]
In each cell, the reaction represented by the formula (1) is performed. That is, hydrogen molecules twice as many as oxygen molecules are required.
[0009]
Usually, oxygen is supplied from the atmosphere, but hydrogen is generated by reacting methanol with water.
[0010]
2 times the amount of hydrogen molecules of oxygen molecules is not a problem if it is supplied to the cell, but when the supply amount of the hydrogen molecules is depleted of hydrogen molecules present in the solid electrolyte membrane 13a~13 in c is (1) a to be used for the reaction, a problem that the solid electrolyte membrane 13A～13 c resulting in corruption.
[0011]
Furthermore, in a cell deficient in hydrogen molecules, carriers carrying electrons are deficient. Since the carriers for carrying the electrons are carried by carbon + ions of the carbon separators 11a to 11d, a situation occurs in which the carbon separators 11a to 11d move. If the carbon separators 11a to 11 are moved, the cell may break down.
[0012]
The present invention has been made in view of the above points, and an object of the present invention is to provide a hydrogen deficiency prevention circuit for a fuel cell that can prevent problems caused by deficiency of hydrogen molecules in a cell.
[0013]
[Means for Solving the Problems]
A fuel cell hydrogen deficiency prevention circuit according to a first aspect of the present invention is a fuel cell in which a plurality of cells that generate electric power by reacting hydrogen and oxygen are connected in series, and is connected between electrodes at both ends of the fuel cell. a plurality of secondary coils connected respectively to the primary coil and each cell was set to 1 / n of the number of turns of the winding number is the primary coil of the secondary coil when the number of each cell is n a transformer that is, the the across the electrodes of the fuel cell is provided between the connection of the primary coil, and a switch which is periodically turned on / off, from each of the secondary coils of equal to each cell Apply voltage.
A fuel cell hydrogen deficiency prevention circuit according to a second aspect of the present invention is a fuel cell in which a plurality of cells that generate electric power by reacting hydrogen and oxygen are connected in series. A plurality of capacitors less than one, and a plurality of switches that periodically and alternately connect the capacitors to cells adjacent to each other among the cells, and from the capacitors through the switches An equal voltage is applied to each cell.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0015]
In FIG. 1, 20 is a hydrogen deficiency prevention circuit. Hereinafter, the configuration of the hydrogen deficiency prevention circuit 20 will be described. The carbon separator 11a functions as a negative electrode of the fuel cell, and the carbon separator 11d functions as a positive electrode of the fuel cell. A load RL (for example, a motor) is connected between the carbon separator 11a and the carbon separator 11d.
[0016]
Between the carbon separator 11a and the intermediate point and the carbon separator 11d of the load RL and the middle point of the load RL, the series connection of the primary coil N1 of the switch PG and transformer T 1 is connected. The switch PG is periodically turned on / off by control means (not shown). The secondary side of the transformer T 1, the coil N21, coil N22, coil N23 are connected in series. The winding ratio between the coil N1 and the coil N21 is set to 3: 1, the winding ratio between the coil N1 and the coil N22 is set to 3: 1, and the winding ratio between the coil N1 and the coil N23 is set to 3: 1.
[0017]
One end of the coil N21 is connected to the carbon separator 11a, the connection point between the coil N21 and the coil N22 is connected to the carbon separator 11b via the diode D1, and the connection point between the coil N22 and the coil N23 is connected to the carbon via the diode D2. Connected to the separator 11c, the end of the coil N23 is connected to the carbon separator 11d via a diode D3.
[0018]
Next, the operation will be described. Hydrogen and oxygen are supplied from both sides of the solid electrolyte membranes 13a to 13c of each cell, respectively. And reaction of Formula (1) is performed in each cell.
[0019]
The voltage generated in each cell is added and generated between the electrodes at both ends of the fuel cell, that is, between the carbon separators 11a (−electrode) and 11d (+ electrode). Then, the load RL connected to the carbon separators 11a (−electrode) and 11d (+ electrode) is driven. If the load RL is a motor, the motor rotates.
[0020]
The switch PG is periodically turned on / on. Therefore, when the switch PG is turned on, electromagnetic energy is accumulated in the coil N1, and when the switch PG is turned off, the electromagnetic energy stored in the coil N1 is transmitted to the secondary side of the transformer T. Since the number of turns of the coils N21, N22, and N23 is set to 1/3 of the number of turns of the coil N1, E / 3 is generated at both ends of each of the coils N21, N22, and N23.
[0021]
This hydrogen deficiency prevention circuit 20 acts so that the hydrogen reaction amount in other cells increases and the fuel cell as a whole has the rated output E even when the amount of hydrogen sent to the middle cell for some reason is deficient. . Further, a voltage lower than the voltage generated at both ends of the other cell is generated between the carbon separators 11b and 11c at both ends of the middle cell where hydrogen is deficient, but the voltage generated at both ends of the coil N22 is E / 3. Therefore, a voltage is generated when no hydrogen deficiency occurs.
[0022]
Therefore, it is possible that the solid electrolyte membrane 13b of the cell deficient in hydrogen generated due to the hydrogen deficiency in the cell is damaged, or that the cell separators 11b and 11c move and the cell fails. Can be prevented.
[0023]
Next, a hydrogen deficiency prevention apparatus for a fuel cell according to a second embodiment will be described with reference to FIG. 2, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. In the figure, 21 is a hydrogen deficiency prevention circuit.
[0024]
The carbon separator 11a is connected to the contact c1, the carbon separator 11b is connected to the contacts c2 and c3, the carbon separator 11c is connected to the contacts c4 and c5, and the carbon separator 11d is connected to the contact c6.
[0025]
Next, the operation will be described. The switches S1 to S3 constitute an interlocking switch S that interlocks. The switches S1 to S3 are switched between a first position (solid line position in the figure) closed at the contacts c2, c4, and c6 and a second position closed at the contacts c1, c3, and c5, respectively. The interlock switch S is periodically switched by control means (not shown).
[0026]
The capacitor C is connected between the terminal d1 of the switch S1 and the terminal d2 of the switch S2, and the capacitor C is also connected between the terminal d2 of the switch S2 and the terminal d3 of the switch S3. Both capacitors C have the same capacity.
Hydrogen and oxygen are supplied from both sides of the solid electrolyte membranes 13a to 13c of each cell, respectively. And reaction of Formula (1) is performed in each cell.
[0028]
The voltage generated in each cell is added and generated between the electrodes at both ends of the fuel cell, that is, between the carbon separators 11a (−electrode) and 11d (+ electrode). Then, the load RL connected to the carbon separators 11a (−electrode) and 11d (+ electrode) is driven. If the load RL is a motor, the motor rotates.
[0029]
By the way, the interlocking switch S is periodically switched between the first value (solid line position in the figure) and the second position. Thus, when the interlock switch S is switched from the first value to the second position, the voltage generated in the middle and right cells is supplied to the left and middle cells. That is, a voltage is supplied to adjacent cells.
[0030]
Even if the amount of hydrogen sent to the middle cell for some reason is deficient by this hydrogen deficiency prevention circuit 21, the amount of hydrogen reaction in other cells is increased so that the fuel cell as a whole has the rated output E. .
[0031]
Accordingly, it is possible that the solid electrolyte membrane 13b of the cell deficient in hydrogen generated due to the occurrence of hydrogen deficiency in the cell is damaged, or that the cell separators 11b and 11c move and the cell fails. Can be prevented.
[0032]
In the first embodiment, the fuel cell is composed of three cells. In the case of n cells, the number of turns of the n secondary coils of the transformer T1 is set to the number of turns of the primary coil. Of 1 / n.
[0033]
Furthermore, in the second embodiment, the fuel cell is composed of three cells. However, in the case of n cells, n-1 capacitors C may be used.
[0034]
【The invention's effect】
According to the fuel cell hydrogen deficiency prevention circuit of the present invention as described in detail above, it is possible to prevent the hydrogen deficiency in the cell fails the cell even if it occurs in advance.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a hydrogen deficiency prevention circuit of a fuel cell according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram showing a hydrogen deficiency prevention circuit of a fuel cell according to a second embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a conventional fuel cell.
[Explanation of symbols]
11a to 11d ... carbon separator, 12 ... catalyst membrane, 13a-13c ... solid electrolyte membrane.

Claims (2)

In a fuel cell in which a plurality of cells that generate electric power by reacting hydrogen and oxygen are connected in series,
Has the fuel cell across multiple secondary coils connected respectively the connected primary coil and between the electrodes in each cell of the winding number of the respective secondary coils when the number of n of each cell A transformer set to 1 / n of the number of turns of the primary coil;
A switch provided between the electrodes at both ends of the fuel cell and the connection with the primary coil, and periodically turned on / off;
Wherein the hydrogen deficiency prevention circuit of the fuel cell being characterized in that a configuration in which a voltage is applied equally to each cell from the secondary coil. In a fuel cell in which a plurality of cells that generate electric power by reacting hydrogen and oxygen are connected in series,
A plurality of capacitors having the same capacity and one less than the number of each cell;
A plurality of switches for alternately switching and connecting the capacitors to cells adjacent to each other among the cells,
Wherein the hydrogen deficiency prevention circuit of the fuel cell being characterized in that a configuration adding equal voltage to each cell via the respective switches from the capacitor.

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