JP2003243015A - Cell state monitoring device for fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell state monitoring device for a fuel cell stack capable of individually monitoring a state of each cell of a fuel cell constituting the fuel cell stack in spite of simple constitution. <P>SOLUTION: A local controller 32 is furnished every cell 2 of the fuel cell of the fuel cell stack 1, each local controller 32 is signal transferred so as to electrically insulate in one direction, a state signal of the cell 2 of the fuel cell is successively transferred to a main controller 4, and the potential difference between the cells 2 of each fuel cell is overcome while wiring and circuit constitution are simplified. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery state monitoring device for a fuel cell stack in which a large number of fuel cells are connected in series by, for example, stacking a large number of fuel cells.

[0002]

2. Description of the Related Art In high voltage applications, it is usual to stack a large number of fuel cells so that a large number of fuel cells are connected in series to form a fuel cell stack. Is. Of course, in this fuel cell stack, the various electrical, cell chemical, and physical states of each fuel cell differ or vary, so it is common to monitor these states of each fuel cell individually. . This is because the fuel cell has various power generation performances due to the fuel flow rate, temperature, pressure, deterioration over time, inherent variations, and the like, and abnormal states to be alarmed also occur independently of each other.

The fuel cell referred to in the present specification may be composed of a single fuel cell or a plurality of fuel cells directly connected in series.

As a fuel cell stack battery state monitoring device used for this type of application, a local controller for detecting the state of the fuel cell (cell voltage, temperature, etc.) and converting it into an electric signal is provided for each fuel cell. It is conceivable to output electric signals in parallel from each local controller to the main controller that integrally processes these electric signals. However, in this case, it is necessary to provide the main controller with a large number of terminals for reception or transmission. Also, in communication between each local controller and the main controller, it is essential to change the electrically isolated reference potential using a photocoupler for both transmission from the main controller to the local controller and transmission from the local controller to the main controller. Becomes Furthermore, the wiring structure becomes complicated due to the multi-channel parallel signal transmission, the work burden of manufacturing, mounting and connecting the wiring furnace is increased, and the required space and the weight of the device are unavoidably increased.

The change of the electric insulation type reference potential will be further described. Each local controller has a fuel cell to which it belongs (as described above, a plurality of fuel cells adjacent to each other are connected in series to each other). The output signal voltage of the signal transfer interface circuit is formed with reference to the fuel cell cell potential to which it belongs, as a result of being supplied with the power supply voltage from the local controller. The reference potential of the output signal voltage of each local controller that becomes a signal is different from each other, and also in the transmission of the command signal from the main controller to each local controller, the reference potential of the output signal voltage of the main controller that becomes this command signal is different from each other. Different from the reference potential of the power supply voltage of the local controller. This is because.

The present invention has been made in view of the above problems, and is a battery for a fuel cell stack capable of individually monitoring the state of each fuel cell constituting the fuel cell stack despite the simple structure. The purpose is to provide a condition monitoring device.

[0007]

According to a first aspect of the present invention, there is provided a battery state monitoring device for a fuel cell stack, which is installed in a fuel cell stack composed of a plurality of fuel cell cells connected in series with each other, and the state of each of the fuel cell cells. In a fuel cell stack battery state monitoring device for detecting each of the fuel cell stacks, the state of each fuel cell is individually detected and a state signal corresponding to the state is output. The status signals are exchanged between the local controllers by exchanging signals in a predetermined order between the local controllers and the main controller that receives the status signals and the local controllers so that they can be electrically insulated or the reference potential can be changed. A signal transmission unit for sequentially transferring and finally transmitting the status signal to the main controller. It is characterized in that.

That is, according to the present invention, the local controller for individually monitoring each fuel cell transfers, for example, the state signals in order of stacking of the fuel cells in order so that they can be electrically insulated or the reference potential can be changed, and finally the main controller can be changed. Since the signal is transmitted to the controller, the circuit configuration and wiring of the signal transmission unit becomes very simple.

For example, as compared with the case where each local controller communicates with the main controller in parallel as described above, the wiring is very simple, and the input / output terminals of the main controller and the input / output interface circuit thereof can be greatly simplified.

There is also an advantage that a command signal can be easily transmitted from the main controller to each local controller through this sequential transfer type transmission path. That is, when bidirectionally communicating between each local controller and the main controller described above, two sets of electrically isolated signal transmission circuits such as photocouplers are required for each local controller, compared to the sequential transfer type transmission. In the path, one set of electrically isolated signal transmission circuits is needed for each local controller.

According to a second aspect of the present invention, in the fuel cell stack cell state monitoring device according to the first aspect, the signal transmission section is individually arranged in the local controller to electrically insulate the state signals from each other. Alternatively, it has as many pairs of transmitters and receivers as the number of the local controllers for transmitting and receiving the reference potential changeable, and configuring a signal transmission path on a ring between each of the local controllers and the main controller, Each local controller is
It is characterized in that the fuel cells are stacked in a row adjacent to the fuel cells stacked in a row.

That is, in this configuration, the signal transmission unit forming the sequential transfer type transmission path has the transmission unit and the reception unit for each local controller, and sequentially transfers the status signal in the stacking direction, so that each fuel cell When cells are stacked, this sequential transfer type transmission path can be sequentially stacked in the stacking direction, and as a result, the transmitter and receiver can be stacked without any special arrangement, so the structure is simple. Can be converted.

For example, the local controller arranged in a predetermined fuel cell unit compares the voltage of the other fuel cell unit obtained based on the received state signal with the predetermined voltage of the fuel cell unit detected by itself. The sum may be sent to an adjacent local controller.

According to a third aspect of the present invention, in the fuel cell stack cell state monitoring apparatus according to the second aspect, the signal transmission unit is the first of the local controllers in which the transfer order of the state signals is first. The command signal is transmitted from the main controller to the local controller, and then the command signal is sequentially transmitted between the local controllers to transmit the command signal to the local controllers.

Thus, it is possible to realize transmission from the main controller to each local controller without adding an electrically isolated signal transmission unit such as a photocoupler.

According to a fourth aspect of the present invention, in the fuel cell stack cell state monitoring device according to the second aspect, the transmitting section and the receiving section that communicate with each other are electrically insulated from each other. According to this configuration, since the transmitter and the receiver are electrically insulated from each other, the power supply voltage is supplied from different fuel cells (or different cell groups), so that the reference potential of the signal voltage as the status signal is supplied. Even if the transmitting unit and the receiving unit to be received are different from each other, the status signals can be sequentially transferred without any problem. Incidentally, in the sequential transfer of the status signal referred to in the present specification, the transmission unit belonging to a local controller may directly send the status signal received by the reception unit belonging to this local controller to the reception unit of the next local controller, Alternatively, it may be transmitted after some processing. Such electrical insulation between the transmitter and the receiver can be realized by, for example, a photo coupler. In this case, the light emitting part of the photocoupler constitutes the transmitting part,
The light receiving part of the photocoupler constitutes the receiving part. In addition, the transmitter and the receiver can be electrically insulated from each other by capacitive coupling, electromagnetic coupling, ultrasonic coupling, or the like.

According to a fifth aspect of the present invention, in the fuel cell stack cell state monitoring device according to the second aspect, the transmitting unit and the receiving unit that communicate with each other are driven by different potential references, and the transmitting unit outputs. The generated signal voltage is level-shifted and applied to the receiving unit.

Thus, the status signal and the command signal can be sequentially transferred only by using a simple level shift circuit. More specifically, since the transmission unit and the reception unit that communicate with each other are supplied with the power supply voltage from the fuel cells adjacent to each other (or the fuel cell group adjacent to each other), the transmission unit and the reception unit communicate with each other. The difference between the reference potentials is small, and by providing a level shift circuit that shifts the voltage level of the output voltage of the transmitter, the difference between the reference potentials of the transmitter and the receiver can be easily compensated. Particularly, in this aspect, it is preferable to sequentially transfer the status signal and the command signal from the high level side to the low level side in terms of simplification of the circuit configuration.

According to a sixth aspect of the present invention, in the fuel cell stack cell state monitoring device according to the first aspect, each of the local controllers outputs each of the fuel cells as the state signal based on a command from the main controller. The cell voltage is detected at the same timing and held until its own transfer timing.

As a result, the states of all the fuel cells at the same time can be detected and transmitted although the transmission timings of the respective transmission units are different. According to this aspect, the voltage of each fuel cell can be added to detect the cell group voltage or the overall voltage, which is particularly important in the voltage detection of the fuel cell.

According to a seventh aspect of the present invention, in the fuel cell stack battery state monitoring device according to the first aspect, each of the local controllers is supplied with operating power from the fuel cell to which the local controller belongs. When the cell stops generating power, the local controller that supplies the power supply voltage can be stopped.

According to an eighth aspect of the present invention, in the fuel cell stack battery state monitoring device according to the first aspect, the local controller disposed in the predetermined fuel cell has the predetermined fuel cell and the predetermined fuel cell. The total voltage of at least one fuel battery cell adjacent in sequence to the fuel battery cell of 1 is applied as the power supply voltage.

With this configuration, it is possible to secure a sufficient power supply voltage for driving the circuit.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the fuel cell stack cell state monitoring device of the present invention will be described in detail with reference to the following embodiments.

[0025]

First Embodiment 1 is a fuel cell stack in which a large number of flat fuel cells 2 are stacked. Inside each fuel cell 2, a high potential positive electrode plate and a low potential plate are sandwiched with a solid electrolyte membrane interposed therebetween. The negative electrode plate is provided, and a separator that also serves as a current collector is provided on both sides thereof, and a hydrogen gas passage through which hydrogen gas flows and an air passage through which air flows are separately provided between the separator and these electrode plates. ing. The structure of the fuel cell itself is not the gist of this embodiment, and the structure of the fuel cell itself is a known matter, so a detailed description thereof will be omitted.

Reference numeral 3 is a local controller unit, 4 is a main controller, 5 is a first light emitting diode, and 6 is a last light receiving diode (photoelectric conversion diode).

The local controller unit 3 is a flat plate-shaped electronic circuit device fixed to one end of each fuel cell 2, and has a local controller 32, a light receiving diode 33, and a light emitting diode 34 mounted on a substrate 31, The local controller 32 is covered with a resin mold portion 35. However, the resin mold portion 35 has holes for guiding light in the portions of the light receiving diode 33 and the light emitting diode 34. The light-receiving diode 33 and the light-emitting diode 34, which are individually provided in two adjacent local controller units 3 and face each other, are capable of one-way optical communication through these light guiding holes. Light receiving diode 3 of the first local controller unit 3
The light emitting diode 3 receives a signal from the main controller 4 through the first light emitting diode 5, and the light emitting diode 34 of the last local controller unit 3 transmits a signal to the main controller 4 through the last light receiving diode 6.

The signal circuit of this circuit is shown in FIG.

The local controller 32 has an A / D converter 321, a microcomputer device 322, a voltage amplification circuit 323, and a power amplification circuit 324, and is composed of one chip. The necessary circuit functions may be configured by hardware logic instead of the microcomputer device 322. The A / D converter 321, the microcomputer 322, the voltage amplification circuit 323, and the power amplification circuit 324 are supplied with power source power from the fuel cell 2 to which the local controller unit 3 to which the self belongs belongs is fixed. If the power supply voltage is insufficient, a booster circuit may be added to the local controller 32.

The A / D converter 321 A / D converts the generated voltage of the fuel cell 2 to which the local controller unit 3 to which it belongs is fixed, and the microcomputer 3
22 is output. When the pulsed light is input to the light receiving diode 33, the voltage amplification circuit 323 voltage-amplifies it and sends it to the microcomputer 322, and the microcomputer 322 outputs from the light receiving diode 33 a digital signal corresponding to the cell voltage detected by itself. The received digital signal is time-sequentially output through the power amplifier circuit 324 and the light emitting diode 34.

(Explanation of Operation) The main controller 4 transmits a voltage detection command signal from the light emitting diode 5, and each local controller 32 transfers the received voltage command signal to the next stage after a predetermined time Δt from the time of reception. As a result, the time required for this voltage detection command signal to be transferred one stage through the local controller unit 3 becomes a preset predetermined time ΔT. After that, each local controller 32 counts the elapsed time from the time when the voltage detection command signal is received, and when the elapsed time reaches a predetermined time, acquires the voltage of the fuel cell cell to which the local controller 32 belongs. That is, the predetermined time of all the local controllers 32 is set until the transfer of the voltage detection command signal is completed, and the voltage sampling of the fuel cells 2 by all the local controllers 32 is individually set so as to be synchronized. ing.

When the elapsed time of each local controller 32 expires, the voltage sampling of each fuel cell is carried out, and the detected voltage is held in the register as a digital signal. Then, the main controller 4 transmits a voltage read command signal. Each local controller 32
When receiving the voltage read command signal, the device outputs a digital signal indicating the voltage held by itself after a predetermined time following the voltage detection command signal composed of a digital signal of a plurality of bits. The timing at which each local controller 32 outputs the digital signal indicating the voltage held by itself is set to a different period after receiving the voltage detection command signal. As a result, the main controller 4 finally reads the voltages of all the fuel cells 2.

According to this embodiment, the voltage of all the fuel cells can be detected with a simple circuit structure compared to the parallel transfer, despite the existence of the potential difference for each fuel cell.

Further, since each local controller 32 can communicate only during the period when the fuel cell is generating electric power, the main controller 4 causes the fuel generation failure due to the length of the digital data following the received voltage read command signal. The battery cell 2 can be specified. Furthermore, when the fuel battery cell 2 is not generating power, the power supply to the local controller 32 is stopped, so that the fuel battery cell 2 does not consume useless stored power during non-power generation. (Modification) In the above embodiment, each local controller 32 executes voltage sampling at the same time by performing voltage sampling after a predetermined time different from the timing of receiving the voltage detection command signal. Then, the voltage may be detected immediately. In this case, the voltage detection is time-sequential, but the adverse effect can be reduced by performing the transfer at high speed. (Modification) In the above embodiment, the electric isolation type signal transfer using the photocoupler was performed, but it is obvious that magnetic coupling, electrostatic coupling or the like may be used instead. (Modification) In the above embodiment, the voltage of each fuel battery cell is detected, but in addition, the temperature, pressure,
Obviously, other status signals such as gas flow rate, gas composition, water content, cooling water temperature may be detected and transferred. (Modification) Another embodiment will be described with reference to FIG.

In this embodiment, as the power source voltage of the A / D converter 321, the microcomputer device 322, the voltage amplifying circuit 323 and the power amplifying circuit 324 which compose each local controller 32, the fuel cell 2 to which it belongs and both sides thereof. The voltage of a total of three fuel cells 2 each including one fuel cell 2 is used. In this way, the power supply voltage can be increased. Of course, by using more fuel cells 2, the local controller 3
A power supply voltage of 2 can also be used.

[0036]

Second Embodiment (Structure) Another embodiment will be described below with reference to FIG. FIG. 4 shows only two local controllers. This embodiment employs a reference potential level down type signal transfer circuit instead of the photocoupler transfer circuit system as an electrically insulating type signal transfer circuit.

Reference numeral 1000 denotes a local controller which converts the voltage of the fuel cell 2 into a digital signal A /
Microcomputer device 100 including D converter
1. Inverter circuit 1 for amplifying the voltage of the signal voltage received from the local controller 1000 at the previous stage 1
002, an inverter circuit 1003 as a power amplifier circuit for outputting the calculated digital signal voltage and the received digital signal voltage to the local controller 1000 at the next stage, and a level down circuit 1004 for leveling down the output voltage of the inverter circuit 1003.

The inverter circuits 1002 and 1003 are ordinary MOS inverter circuits in which a MOS transistor T1 functioning as a load resistance and a MOS transistor T functioning as a switching element (driver element) are connected in series, and the connection point serves as its output end. Consists of.

The level down circuit 1004 is formed by connecting a predetermined number of junction diodes D and resistors R in series, and the anode of the highest junction diode D is connected to the output contact of the inverter circuit 1003 in the preceding stage, and the resistors are connected. The lower end of R is connected to the lower power supply line of the local controller 1000. The connection point between the lowest junction diode D and the resistor R is connected to the gate electrode of the MOS transistor T that forms the switching element of the inverter circuit 1002.

(Operation) When the output potential of the inverter circuit 1003 at the preceding stage becomes high level, the level down circuit 100
A high potential close to the high-potential power supply potential of the inverter circuit 1003 (local controller 1000) in the previous stage is applied to the inverter 4, but this potential is leveled down by a predetermined number of junction diodes D, and the inverter circuit 1002 (local controller in the next stage). It becomes a high potential close to the high power supply potential of 1000). As a result, this next-stage inverter circuit 1
002 outputs a low level.

Further, when the output potential of the inverter circuit 1003 at the preceding stage becomes low level, the level down circuit 1004.
Is applied with a potential close to the low power supply potential of the inverter circuit 1003 (local controller 1000) in the previous stage, this potential is leveled down by a predetermined number of junction diodes D, and the inverter circuit 1002 (local controller 1000) in the next stage. It becomes a high potential close to the low power supply potential of. As a result, this next-stage inverter circuit 100
The MOS transistor forming the second switching element is turned off, and the inverter circuit 1002 outputs a high level.

By doing so, a complicated and expensive electric insulation type signal transmission circuit such as photo-coupler coupling can be omitted, so that the circuit configuration can be simplified and the cost can be reduced. (Modification) Of course, in this embodiment as well, the power supply voltage of the local controller 1000 can be obtained from a plurality of fuel cells 2 as shown in FIG. In addition, it goes without saying that the fuel cell 2 of FIG. 4 may be composed of a plurality of series-connected fuel cells.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a fuel cell stack cell state monitoring device of the present invention.

FIG. 2 is a block circuit diagram of the fuel cell stack cell state monitoring device of FIG.

FIG. 3 is a circuit diagram showing a modification of increasing the power supply voltage in FIG.

FIG. 4 is a partial circuit diagram showing a fuel cell stack cell state monitoring device according to a second embodiment.

[Explanation of symbols]

1 Fuel cell stack 2 Fuel cell 3 Local controller unit 4 Main controller 5 light emitting diode 6 Light receiving diode 32 Remote controller device 33 light receiving diode 34 light emitting diode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toru Mizuno             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Yu Kadokawa             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Gotoshi Kato             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 5H027 AA02 KK54

Claims (8)

[Claims] 1. A battery state monitoring device for a fuel cell stack, which is installed in a fuel cell stack comprising a large number of fuel cells connected in series to each other and detects the state of each fuel cell, wherein each fuel cell is a fuel cell stack. And a plurality of local controllers that individually detect the state of each of the fuel cells and output a state signal corresponding to the state, a main controller that receives the state signal, and each of the local controllers. A signal that sequentially transfers the status signals between the local controllers by exchanging signals in a predetermined order between the controllers so that they can be electrically isolated or the reference potential can be changed, and finally sends the status signals to the main controller. A fuel cell stack cell state monitoring device comprising: a transmission section. 2. The cell status monitoring device for a fuel cell stack according to claim 1, wherein the signal transmission unit is individually arranged in the local controller so that the status signals can be electrically insulated from each other or the reference potential can be changed. The number of pairs of the transmission unit and the reception unit for transmitting and receiving to the local controller, the signal transmission path on the ring between the local controller and the main controller is configured, each local controller, A fuel cell stack battery state monitoring device, characterized in that the fuel cell units are stacked in a row adjacent to the fuel cells stacked in a row. 3. The fuel cell stack cell state monitoring device according to claim 2, wherein the signal transmission unit is the first local controller in which the state signals are transferred first among the local controllers. A fuel cell stack cell state characterized by transmitting a command signal from the main controller and then sequentially transmitting the command signal between the local controllers to thereby transmit the command signal to the local controllers. Monitor device. 4. The fuel cell stack cell state monitoring device according to claim 2, wherein the transmitter and the receiver communicating with each other are electrically insulated from each other. Monitor device. 5. The fuel cell stack cell state monitoring device according to claim 2, wherein the transmitter and the receiver communicating with each other are driven by different potential references, and the signal voltage output from the transmitter is A cell state monitoring device for a fuel cell stack, which is level-shifted and applied to the receiving unit. 6. The fuel cell stack battery state monitoring device according to claim 1, wherein each of the local controllers simultaneously outputs the voltage of each of the fuel cells as the state signal based on a command from the main controller. A fuel cell stack cell state monitoring device, which detects the timing and holds it until its own transfer timing. 7. The fuel cell stack battery state monitoring device according to claim 1, wherein each of the local controllers is supplied with operating power from the fuel battery cell to which the local controller belongs. Battery condition monitoring device. 8. The fuel cell stack battery state monitoring device according to claim 1, wherein the local controller disposed in the predetermined fuel cell is arranged in the predetermined fuel cell and the predetermined fuel cell. A battery state monitoring device for a fuel cell stack, wherein a total voltage of at least one fuel battery cell adjacent in order is applied as a power supply voltage.