JP2000285945A - Voltage detection method for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily detect an existence of a cell with an abnormally low voltage at low cost. SOLUTION: A fuel cell voltage detection device 10 detects the voltage of a solid polymer fuel cell 11. The fuel cell voltage detection device 10 is provided with a total output voltage detector 12 detecting a total voltage of the fuel cell, a block voltage detector 13 detecting a block voltage of a cell block 24 comprising arbitrary number of cells, and a detecting and calculating unit 14 calculating a first average cell voltage Vm of cells from the total voltage, calculating a determination reference voltage V33 from the first average cell voltage when an abnormally low voltage of a cell is assumed to be present, calculating a second average cell voltage Vb from the block voltage, and detecting an existence of a cell with an abnormally low voltage when the second average cell voltage becomes equal to or less than the determination reference voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell voltage detection method for detecting an output voltage of a fuel cell, and more particularly to a fuel cell voltage detection method capable of specifying a cell whose voltage has dropped.

[0002]

2. Description of the Related Art A fuel cell is formed by stacking a plurality of cells each having a pair of electrodes opposed to each other with a solid polymer electrolyte membrane interposed therebetween. The voltage of this fuel cell has been detected by measuring the total voltage output from the entire fuel cell.

[0003]

As described above, since the voltage of the fuel cell is detected by measuring the total voltage output from the entire fuel cell, the cell whose voltage has dropped abnormally is specified. I couldn't do that.

In order to detect the abnormal drop in the voltage of a specific cell, the voltages of all the cells of the fuel cell must be individually measured. In this case, the detection circuit becomes complicated and the cost increases. I will.

An object of the present invention has been made in view of the above circumstances, and provides a fuel cell voltage detecting method capable of easily detecting, at low cost, the presence of a cell whose voltage has dropped abnormally. It is in.

[0006]

According to a first aspect of the present invention, there is provided a fuel cell in which a plurality of cells each having a pair of electrodes opposed to each other with a solid polymer electrolyte membrane interposed therebetween are stacked in series. In the voltage detection method, a block voltage between any number of the cells stacked in series is detected, and a voltage calculated based on the block voltage is calculated based on a total cell voltage stacked in series. When the voltage becomes equal to or lower than the determination reference voltage calculated based on the divided voltage corresponding to the number of cells, the presence of the cell whose voltage has decreased is determined.

According to a second aspect of the present invention, there is provided a voltage detecting method for detecting an output voltage of a fuel cell in which a plurality of cells each having a pair of electrodes arranged opposite to each other with a solid polymer electrolyte membrane interposed therebetween are stacked in series. Provide a photocoupler that switches between ON and OFF when the block voltage between the cells stacked in an arbitrary number becomes lower than a predetermined voltage, and turns on the light emitting element according to the output from the photocoupler. , And turn off the light.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

[A] First Embodiment (FIGS. 1 and 2) FIG. 1 shows a fuel cell voltage detecting apparatus for implementing a first embodiment of a fuel cell voltage detecting method according to the present invention. FIG.

The fuel cell voltage detecting device 10 shown in FIG.
Detects a voltage drop of a cell 16 (described later) of the polymer electrolyte fuel cell 11 during power generation, and has a total output voltage detector 12, a block voltage detector 13, and a detection calculator 14. It is composed.

The polymer electrolyte fuel cell 11 has a structure in which a plurality of cells 16 (unit cells) shown in FIG. 2 are stacked in series to constitute a module, and a hydrogen gas supply system 15 and an air supply system 25 are provided. Connected. Each cell 16 is arranged in contact with a solid polymer electrolyte membrane 17 such as a polymer ion exchange membrane, an anode 18 and a cathode 19 joined to opposing surfaces of the solid polymer electrolyte membrane 17, respectively. And a cathode substrate 21 arranged in contact with the cathode 19.

The anode 18 and the cathode 19 are mainly composed of carbon carrying platinum and have a diffusion path through which gas or water can diffuse. In the anode 18 and the cathode 19, an electrochemical reaction described below is performed.

An anode gas flow path 22 for flowing hydrogen gas as an anode gas is formed in the anode substrate 20 on the side in contact with the anode 18. In the cathode base material 21, a cathode gas flow path 23 for flowing air (or oxygen gas) as a cathode gas is formed on the side in contact with the cathode 19. The anode substrate 20 and the cathode substrate 21 are formed of a porous material such as a carbon material, and are configured to be permeable to gas or water.

In the cell 16 configured as described above,
The hydrogen gas introduced into the anode 18 via the anode gas flow path 22 of the anode substrate 20 is oxidized in the anode 18 to form protons (H ⁺ ).
It moves through the solid polymer electrolyte membrane 17 to reach the cathode 19, where it is reduced by an electrochemical reaction with oxygen in the air introduced through the cathode gas flow passage 23 of the cathode substrate 21, Turns into water. With this electrochemical reaction, a voltage is generated between the anode 18 and the cathode 19.

The hydrogen gas supply system 15 includes a hydrogen cylinder, a pressure reducing valve, and a hydrogen supply solenoid valve (not shown) arranged in this order. The hydrogen supply solenoid valve is connected to the polymer electrolyte fuel cell 11. By adjusting the opening degree of the hydrogen supply solenoid valve of the hydrogen gas supply system 15, the anode gas flow path 22 of the anode substrate 20 in each cell 16 of the polymer electrolyte fuel cell 11 is adjusted.
Hydrogen gas is supplied at a suitable flow rate.

The air supply system 25 has an air supply fan connected to the polymer electrolyte fuel cell 11. By adjusting the rotation speed of the air supply fan, an appropriate flow rate of air is supplied to the cathode gas flow path 23 of the cathode substrate 21 in each cell 16 of the polymer electrolyte fuel cell 11.

The total output voltage detector 12 detects a total voltage output from the entire polymer electrolyte fuel cell 11. This detection voltage is output from the total output voltage detector 12 to the detection calculator 14.

The block voltage detector 13 detects a block voltage generated in a cell block 24 in which an arbitrary number of cells 16 are stacked in the polymer electrolyte fuel cell 11. This detection voltage is output from the block voltage detector 13 to the detection calculator 14.

The detection computing unit 14 first calculates a first average cell voltage Vm based on the total voltage of the polymer electrolyte fuel cell 11 detected by the total output voltage detector 12, and calculates a block voltage detector 13 calculates the second average cell voltage Vb based on the detected block voltage of the cell block 24. The first average cell voltage Vm and the second average cell voltage Vb are detected when the same load is acting on the polymer electrolyte fuel cell 11.

Next, the detection arithmetic unit 14 calculates the judgment reference voltage V _B when it is assumed that one cell 16 having a cell voltage of 0 volt exists in a certain cell block 24 by the first average cell voltage Vm. Is calculated from Equation (1).

V _B = {(n−1) / n} × Vm (1) where n is the number of cells 16 constituting the cell block 24.

When the second average cell voltage Vb becomes equal to or lower than the judgment reference voltage V _B (Vb ≦ V _B ), the detection arithmetic unit 14 detects a cell whose voltage has abnormally dropped in the cell block 24. It is determined that 16 exists.

The detection arithmetic unit 14 similarly performs the above-described operation on the other cell blocks 24 detected by the block voltage detector 13, and in the cell block 24, the presence of the cell 16 whose voltage has dropped abnormally Is detected.

Therefore, according to the above embodiment, the following effects can be obtained.

A total output voltage detector 12 detects a total voltage of the polymer electrolyte fuel cell 11 and outputs a block voltage detector 13.
Detects the block voltage of an arbitrary cell block 24, and the detection calculator 14 generates an abnormally low voltage in the cell 16 based on the first average cell voltage Vm calculated from the total voltage of the polymer electrolyte fuel cell 11. when calculating the criterion voltage V _B on the assumption, the second average cell voltage Vb calculated from the block voltage becomes equal to or less than the determination reference voltage V _B and,
Since the presence of the cell 16 whose voltage has dropped abnormally is detected, a detection circuit for individually detecting the cell voltages of all the cells 16 is not required.
6 can be easily detected at low cost.

[B] Second Embodiment (FIG. 3) FIG. 3 is an electric circuit showing a fuel cell voltage detecting apparatus for implementing a second embodiment of the fuel cell voltage detecting method according to the present invention. FIG. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The fuel cell voltage detecting device 30 according to the second embodiment detects a voltage drop of the cells 16 constituting the polymer electrolyte fuel cell 11.
1, main resistor 32, transistor 33, LED34
(Light emitting diode) and the detection determination unit 35.

The photocoupler 31 includes a light emitting element 36 such as a light emitting diode and a light receiving element 37 such as a phototransistor. Polymer electrolyte fuel cell 11
In, a block voltage generated in an arbitrary cell block 24 in which an arbitrary number of cells 16 are stacked can be input to a light emitting element 36 of a photocoupler 31 via a main resistor 32. The main resistor 32 is connected in series to the light emitting element 36 of the photocoupler 31.

The resistance value of the main resistor 32 is such that when the block voltage is equal to or lower than the specified voltage, the light emitting operation of the light emitting element 36 of the photocoupler 31 is stopped and the light receiving element 37 is turned off.
The value is set to a value for performing the F operation. For example, cell block 2
In the case where the number of cells 16 constituting 4 is four, when the block voltage is 1.6 V or less (the average cell voltage is 400 mV) or less,
The cell 16 whose voltage is abnormally lowered is stored in the cell block 24.
Is assumed, the resistance value of the main resistor 32 is set to a value at which the minimum voltage (that is, the specified voltage) at which the light emitting element 36 of the photocoupler 31 emits light is 1.6 V.

A current flows through the transistor 33 when the light receiving element 37 of the photocoupler 31 is turned off and the potential at the point A increases. At this time, the potential at the detection point of the determiner 35 decreases, and the presence of an abnormally low voltage cell can be detected. Further, a current flows through the LED 34 via the first sub-resistor 38 so that the LED 34 is turned on and the presence of the abnormal voltage drop cell can be visually recognized.

When the light receiving element 37 of the photocoupler 31 is ON, the potential at the point A is low, so that no current flows through the transistor 33. At this time, LE
D34 is turned off, and the potential at the detection point of the detection determiner 35 rises.

The detection determiner 35 is connected to the light receiving element 37 side of the photocoupler 31 via the transistor 33, detects the potential at the detection point as described above, and applies an abnormal voltage to the cell 16 of the cell block 24. Detect that a drop has occurred.

Reference numeral 39 in FIG. 3 denotes a second sub resistor,
Reference numeral 40 represents a third sub-resistor, reference numeral 41 represents a first diode, and reference numeral 42 represents a second diode.

Next, the operation of the fuel cell voltage detecting device 30 will be described.

The cells 16 constituting the cell block 24 include:
When there is no cell 16 whose voltage is abnormally reduced,
When the voltage applied to the light emitting element 36 of the photocoupler 31 becomes equal to or higher than the specified voltage, the light emitting element 36 emits light. Therefore, the light receiving element 37 of the photocoupler 31 is turned on, the potential at the point A is lowered, no current flows through the transistor 33, and the LED 34 is turned off. The detection determiner 35 detects that the potential of the detection point is high, and determines that the voltage of the cells 16 constituting the cell block 24 is normal.

The cells 16 constituting the cell block 24 include:
When there is a cell 16 with an abnormally low voltage, the voltage applied to the light emitting element 36 of the photocoupler 31 becomes equal to or lower than the specified voltage, and the light emitting element 36 stops emitting light. Therefore, the light receiving element 37 of the photocoupler 31
The FF operation causes the potential at the point A to increase, and the transistor 33
And the LED 34 lights up. Detection determiner 35
Detects that the potential of the detection point is high,
The cell 1 having the abnormally low voltage is replaced with the cell 16 constituting the cell 4
6 is detected.

Therefore, according to the above embodiment, the following effects can be obtained.

The block voltage of a cell block 24 comprising an arbitrary number of stacked cells 16 is applied to a main resistor 32.
Is input to the light-emitting element 36 of the photocoupler 31 via the interface, and the light-emitting element 36 of the photocoupler 31 stops emitting light by the input of the block voltage whose resistance value of the main resistor 32 is equal to or less than the specified voltage. Set the light receiving element 37 to O
The detector / determiner 35, which is set to a value for performing the FF operation and connected to the light receiving element 37 of the photocoupler 31 via the transistor 33, turns off the light receiving element 37 so that the cell 16 constituting the cell block 24 is turned off. Since the abnormal drop in the voltage is detected, a detection circuit for individually detecting the cell voltages of all the cells 16 is not required. Therefore, the presence of the cell 16 in which the voltage has abnormally dropped can be easily detected at low cost.

As described above, the present invention has been described based on the above embodiment, but the present invention is not limited to this.

In the second embodiment, FIG.
The detection determiner 35 may be connected to the point A, as shown by the chain line. When the potential at the point A is low, the detection determiner 35 turns on the light receiving element 37 of the photocoupler 31 and determines that the voltage of the cell 16 of the cell block 24 is normal. When the potential at the point A is high, the detection determining unit 35 sets the light receiving element 37 of the photocoupler 31 to the OF position.
The F operation is performed to detect that an abnormally low voltage exists in the cells 16 of the cell block 24.

[0041]

As described above, according to the voltage detection method for a fuel cell according to the first aspect of the present invention, a plurality of cells each having a pair of electrodes opposed to each other with a solid polymer electrolyte membrane interposed therebetween are provided. In a voltage detection method for detecting an output voltage of a fuel cell stacked in series, a block voltage between any number of the cells stacked in series is detected, and a voltage calculated based on the block voltage is stacked in series. When the voltage becomes equal to or less than the determination reference voltage calculated based on the divided voltage corresponding to an arbitrary number of cells calculated from the total cell voltage, the presence of the cell whose voltage has decreased is determined. The presence of a cell whose voltage has dropped abnormally can be easily detected at low cost.

According to the method for detecting voltage of a fuel cell according to the second aspect of the present invention, a fuel cell comprising a plurality of cells having a pair of electrodes opposed to each other with a solid polymer electrolyte membrane interposed therebetween is stacked in series. In the voltage detection method for detecting the output voltage, when the block voltage between any number of the cells stacked in series becomes equal to or lower than a predetermined voltage, ONN, O
A photocoupler that switches the FF is provided, and the turning on and off of the light emitting element is controlled in accordance with the output from the photocoupler. Therefore, the presence of a cell whose voltage has dropped abnormally can be easily detected at low cost. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a fuel cell voltage detecting device that implements a first embodiment of a fuel cell voltage detecting method according to the present invention.

FIG. 2 is a schematic configuration diagram showing cells constituting the fuel cell of FIG.

FIG. 3 is an electric circuit diagram showing a fuel cell voltage detection device that implements a second embodiment of the fuel cell voltage detection method according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 fuel cell voltage detector 11 polymer electrolyte fuel cell (fuel cell) 12 total output voltage detector 13 block voltage detector 14 detection calculator 16 cell 24 cell block 30 fuel cell voltage detector 31 photocoupler 32 main resistor (Resistor) 36 Light emitting element 37 Light receiving element

Continued on the front page (72) Inventor Ryuji Hatayama 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Inventor Kazuhiro Tajima 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture No. Sanyo Electric Co., Ltd. F-term (reference) 5H026 AA06 5H027 AA06 KK54

Claims (2)

[Claims] 1. A voltage detecting method for detecting an output voltage of a fuel cell in which a plurality of cells each having a pair of electrodes arranged opposite to each other with a solid polymer electrolyte membrane interposed therebetween is detected. A voltage calculated based on the block voltage between the cells is calculated based on a divided voltage corresponding to an arbitrary number of cells calculated from a total cell voltage stacked in series. A method for detecting the voltage of a fuel cell, comprising: determining the presence of the cell whose voltage has decreased when the voltage has become equal to or less than the determined reference voltage. 2. A voltage detection method for detecting an output voltage of a fuel cell in which a plurality of cells each having a pair of electrodes arranged opposite to each other with a solid polymer electrolyte membrane interposed therebetween is detected. A photocoupler that switches between ON and OFF when the block voltage between the cells becomes equal to or lower than a predetermined voltage is provided, and the turning on / off of the light emitting element is controlled in accordance with the output from the photocoupler. Fuel cell voltage detection method.