JP2007173206A - Method of starting fuel cell system, and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of starting a fuel cell system and the fuel cell system surely protecting the fuel cell from such a phenomenon deteriorating cells constituting the fuel cell at starting the fuel cell system with simple structure and starting process. <P>SOLUTION: The method of starting the fuel cell system comprises a process of operating a fuel cell protection means based on an output of one cell out of the cells constituting the fuel cell after starting supply of fuel to the fuel cell, when starting the fuel cell system provided with the fuel cell, the fuel cell protection means, and a voltage conversion device, a process of starting the voltage conversion device basing on a signal transmitted from the fuel cell protection means after the fuel cell protection means is operated, and a process of switching the power supply to the fuel cell protection means to the output of the voltage conversion device after the voltage conversion device is operated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for starting a fuel cell system including a fuel cell that generates power when fuel is supplied, and a fuel cell system.

  In recent years, power consumption of mobile devices typified by mobile phones has been steadily increasing as the functionality of the devices has increased, and improving the capacity of the power source has become a major issue. Under such circumstances, fuel cells are attracting attention as small energy power sources with high energy density.

  In a fuel cell, two types of electrodes are sandwiched between electrolytes, and electricity is generated by oxidizing a fuel such as hydrogen or methanol at a fuel electrode and reducing oxygen in the atmosphere at an oxygen electrode. Among the fuel cells, the polymer electrolyte fuel cell (PEFC) is capable of generating power near room temperature and has high output density and can be miniaturized, so it is expected to be applied as a power source for portable devices. Has been.

When a fuel cell is used as a power source, a practical operating voltage of one fuel cell is around 0.3 to 0.5V. Therefore, in order to obtain a voltage necessary for a practical load, a required number of cells are connected in series to obtain a predetermined high output voltage.

  Thus, by connecting the cells of the fuel cell in series, a high voltage / high output fuel cell can be obtained. However, when a plurality of cells are used in series connection, it is caused by variations in the output of each cell. As a result, the power generation performance of the fuel cell as a cell aggregate deteriorates.

  Further, at the time of starting the fuel cell, when the external load has a motor or a capacitive load, the rush current flows from the fuel cell, and the cell voltage is abruptly lowered to easily cause a reversal state.

  In particular, when power generation is started after the fuel cell system has been stopped for a long period of time, the output characteristics deteriorate due to an increase in internal resistance of the cells constituting the fuel cell due to drying of the electrolyte membrane, etc. The rated power cannot be obtained. Furthermore, due to an increase in internal resistance and variations in fuel supply, some of the plurality of cells are poled, causing a problem that the cells deteriorate significantly.

Therefore, the power generation state of the fuel cell is monitored, and if the monitoring result is smaller than the lowest threshold that can be tolerated from the control table, the control device that limits the output current of the fuel cell and prevents cell deterioration in advance. Is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 7-272736 (page 4, FIG. 1)

  In order to protect the fuel cell from deterioration, it is necessary to operate a control device that prevents deterioration of the cell of the fuel cell before taking out electric power from the fuel cell. However, if power is extracted from the fuel cell in order to obtain power for operating the control device that prevents cell deterioration, it is impossible to prevent cell deterioration during the operation. In addition, it is possible to provide power storage means etc. inside the system to operate the control device that prevents cell deterioration, but when the power storage means etc. is in an overdischarged state, it is not possible to take out power from the power storage means. Since it is impossible, it is impossible to obtain an output from the fuel cell after operating a control device that prevents cell deterioration. Therefore, under any circumstance, when the fuel cell system is started, it is necessary to operate a means for reliably protecting the fuel cell from deterioration. Otherwise, the fuel cell may be overloaded when the fuel cell system is started. There is a problem in that the cell deteriorates due to polarization or the like, the life of the fuel cell system is shortened, and the long-term reliability of the fuel cell system is lowered.

  In the present invention, this type of problem is solved, and the fuel cell can be reliably secured from a phenomenon that causes deterioration of the cells constituting the fuel cell at the start-up of the fuel cell system with a simple start-up process and configuration. It is an object of the present invention to provide a fuel cell system start-up method and a fuel cell system that are protected.

The present invention for achieving the above object
Fuel cell protection comprising a fuel cell comprising a plurality of cells that generate power by supplying fuel, fuel cell protection means for protecting the fuel cell, and one or more voltage converters that receive the output of the fuel cell as input In the fuel cell system start-up method, power is supplied from at least one of the fuel cell and the voltage converter, and the output power of the voltage converter is supplied to the load. When the fuel cell system is started, the fuel is supplied to the fuel cell. The step of operating the fuel cell protection means from the output of one of the cells constituting the fuel cell after the start of supply as a source, and the voltage converter based on the signal transmitted by the fuel cell protection means after the fuel cell protection means operates By starting the, it is possible to avoid inversion or overload that causes deterioration of the fuel cell. Here, the fuel cell protection means only needs to have a function of preventing or avoiding a phenomenon that causes deterioration of the cell such as inversion or overload of the fuel cell. Here, the voltage converter is a circuit that adjusts a DC voltage input to the voltage converter and outputs a stabilized voltage, and the stabilized voltage may be a DC voltage or an AC voltage.

  After starting up the voltage converter, it is possible to make the load of each cell constituting the fuel cell uniform by switching the power source so that the power source of the fuel cell protection means is obtained from the voltage converter.

  The power source of the fuel cell protection means uses the output of one cell as a source to operate the fuel cell protection means, and the cell as the power source does not cause a reversal.

  The fuel cell has at least cells connected in series, and the cell that supplies power to the fuel cell protection means when the fuel cell system is started is connected to the ground potential electrode of the cells connected in series constituting the fuel cell. By using one cell as a negative electrode, a stable output can be obtained.

  In addition, one cell that supplies power to the fuel cell protection means at the start of the fuel cell system is the electrode having the largest positive potential difference with respect to the ground potential among the series connected cells constituting the fuel cell, or the most One of the cells having an electrode having a large negative potential difference may be used.

Further, the fuel cell has a main system capable of supplying power to the first voltage conversion device in which a plurality of cells are connected in series and a cell different from the main system, and the fuel cell protection means when the fuel cell system is started The same effect can be obtained by selecting one of the cells other than the main system for supplying power to the cell.
In addition, the configuration of the fuel cell may be one cell group connected in series or a plurality of cells.

  When the fuel cell protection means cannot be activated and driven only by the output of the fuel cell, the second voltage converter is used, and the second voltage converter has a plurality of cells constituting the fuel cell. One of the cells is connected, and the fuel cell protection means is operated by the output of the second voltage converter.

  That is, a fuel cell composed of a plurality of cells that generate power by supplying fuel, a fuel cell protection means that protects the fuel cell, a first voltage converter that receives the output of the fuel cell, and a second A fuel cell comprising a voltage converter, wherein the fuel cell protection means receives power from at least one of the second voltage converter and the first voltage converter, and supplies the output power of the first voltage converter to the load. In the battery system activation method, when the fuel cell system is activated, a step of operating the second voltage converter using the output of one of the cells constituting the fuel cell after the start of fuel supply to the fuel cell; A step of operating the fuel cell protection means using the output of the second voltage conversion device after the activation of the second voltage conversion device; and the fuel cell protection means transmits after the fuel cell protection means operates Starting the first voltage converter based on the number, and after starting the first voltage converter, the power supply to the fuel cell protection means from the output of the second voltage converter to the first voltage converter And switching the power supply to the fuel cell protection means from the output of the second voltage converter to the output of the first voltage converter, and then stopping the operation of the second voltage converter. This avoids inversion, overload, and the like that cause deterioration of the fuel cell.

  The power source for the fuel cell protection means and the first voltage converter is obtained from the second voltage converter, and after the first voltage converter is activated, the power source for the fuel cell protection means and the first voltage converter is Is obtained from the first voltage converter.

  As a cell connected to the second voltage converter at that time and supplying power to the second voltage converter, at least one fuel cell connected in series is selected with the ground potential electrode as the negative electrode of the cell. By doing so, it is possible to stably operate the second voltage conversion device.

  Further, a cell connected to the second voltage converter and supplying power to the second voltage converter is at least an electrode having the largest negative potential difference with respect to the ground potential in the cells of the fuel cell connected in series. By using one of the cells having the most positive electrode having the largest potential difference, the fuel cell protection means can obtain a large potential difference with respect to the ground potential. It is possible to operate the electronic elements having a high minimum operating voltage that constitute the fuel cell protection means.

  Further, when at least some of the plurality of cells are connected in series, the fuel cell has one cell connected to the second voltage converter and supplying power to the second voltage converter. One cell different from the cells constituting the series connection may be used. Moreover, you may operate a 1st voltage converter using the output of a 2nd voltage converter.

  In order to realize such a starting method, a fuel cell system includes a fuel cell composed of a plurality of cells that generate power by supplying fuel, a fuel cell protection means for protecting the fuel cell, and an output of the fuel cell. One or more voltage conversion devices that receive the input, and the power source of the fuel cell protection means is supplied with power from the output of one of the plurality of cells constituting the fuel cell, and the fuel cell The protection means includes a state signal output terminal that outputs a signal indicating the output state of the fuel cell, the state signal output terminal is connected to the voltage converter, and the voltage converter operates based on an input signal from the state signal output terminal. And the voltage conversion device is started after the fuel cell protection means is operated, thereby obtaining a configuration that avoids inversion or overload that causes deterioration of the fuel cell.

  When the fuel cell protection means and the voltage converter cannot be driven only by the output of one cell, the fuel cell is composed of a plurality of cells that generate power by supplying fuel, and the fuel cell that protects the fuel cell A protection means, a first voltage conversion device that receives the output of the fuel cell, and a second voltage conversion device, and the input of the second voltage conversion device includes a plurality of cells constituting the fuel cell. One cell is connected, the fuel cell protection means includes a state signal output terminal for outputting a signal indicating the output state of the fuel cell, the state signal output terminal is connected to the first voltage converter, and the first voltage conversion The device switches the operation based on the input signal from the status signal output terminal, the voltage converter is activated based on the signal transmitted by the fuel cell protection means after the fuel cell protection means is activated, and the first voltage conversion device Output power Supplied to the load. A cell connected to the second voltage converter and supplying power to the second voltage converter is selected by selecting at least one cell of a series-connected fuel cell having the ground potential electrode as the negative electrode of the cell. The second voltage converter can be operated stably.

  Further, a cell connected to the second voltage converter and supplying power to the second voltage converter is at least an electrode having the largest negative potential difference with respect to the ground potential in the cells of the fuel cell connected in series. By using one of the cells having the most positive electrode having the largest potential difference, the fuel cell protection means can obtain a large potential difference with respect to the ground potential. It is possible to operate the electronic elements having a high minimum operating voltage that constitute the fuel cell protection means.

  Further, when at least some of the plurality of cells are connected in series, the fuel cell has one cell connected to the second voltage converter and supplying power to the second voltage converter. One cell different from the cells constituting the series connection may be used. The output of the second voltage converter may be used to drive not only the fuel cell protection means but also the first voltage converter.

  The second voltage converter has an operation switching signal input terminal, and switches the operation of the second voltage converter by a signal input to the operation switching signal input terminal. When switching the operation of the second voltage converter, for example, a threshold is set for the input signal in order to stop the operation of the second voltage converter.

  By operating the electronic devices such as the fuel cell protection means and the second voltage converter using the output of only one cell, the cell does not cause a reversal. Because at least the electronic devices connected to one cell have the lowest drive voltage, so if the output voltage of the cell falls below that voltage value, the operation of the electronic devices stops and requires power. Therefore, the cell connected to the electronic device is not in a reversed state. Also, when trying to extract power from the cell, if the fuel cell voltage drops and the cell voltage becomes 0 V just before the inversion state, the output power is also 0 W, and no more power can be taken out Since it is impossible, the cell does not go below 0V and does not cause reversal.

  Therefore, at the time of start-up, by using the power of only one cell for the fuel cell protection means, the cell is not reversed, and the other cells are protected from polarity reversal by the fuel cell protection means. When the fuel cell protection means cannot operate with the power of only one cell, the second voltage converter is used to operate the fuel cell protection means. Similarly, the power supply of the second voltage converter is also connected to one cell. By using only electric power, the cell does not cause reversal, and other cells are protected from reversal by the fuel cell protection means.

  According to the present invention, when the fuel cell system is activated, when the voltage converter is activated, the fuel cell protection means that reliably protects the fuel cell from deterioration is activated. It is possible to prevent cell overload, inversion, and the like that occur due to generation or failure of the cell electrode. This makes it possible to prevent deterioration of the cell even when the fuel cell system is started up, so that it does not deteriorate the fuel cell under any circumstances, and it is possible to extend the life of the fuel cell system, In addition, the long-term reliability of the fuel cell system is improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In general, when a polymer electrolyte fuel cell (PEFC) is used as a fuel cell, hydrogen used as a fuel for the fuel cell is in a state of liquid hydrogen, hydrogen gas, or hydrogen atom in a high pressure cylinder, a hydrogen storage alloy. And stored by at least one means selected from the group consisting of carbon materials such as carbon nanotubes and fullerenes. On the other hand, it is also possible to extract hydrogen by chemical changes such as reforming and hydrolysis of hydrogen-containing chemical substances such as alcohol, inorganic chemical hydride, and organic chemical hydride.

  On the other hand, when using a direct fuel cell such as a direct methanol fuel cell (DMFC), methanol is used as the fuel. Moreover, it is also possible to use alcohols, such as dimethyl ether (DME), 2-propanol, and ethanol, as a fuel instead of methanol. Furthermore, an aqueous solution of a metal hydride complex compound such as sodium borohydride can be used as a fuel for a direct fuel cell. A cell is a minimum constituent unit that can obtain an electromotive voltage by supplying fuel and can extract electric power. Specifically, in the case of PEFC, a cell is a catalyst layer disposed on both sides of a solid polymer electrolyte membrane, and the air permeability and fluidity of a fuel gas or liquid fuel such as a gas diffusion layer on the upper surface of each catalyst layer. The unit is provided with a layer having electric conductivity and further having a current collector disposed on the upper surface of each gas diffusion layer and the like, and these members are sandwiched between them. In the present application, the fuel supply method for the fuel cell is not limited as long as the fuel is supplied in such a way that a sufficient amount of power can be supplied to the load of the fuel cell system. .

  The present invention can be applied to any type of fuel cell.

  The fuel cell protection means only needs to have a function of preventing or avoiding a phenomenon that causes deterioration of the cell such as inversion or overload of the fuel cell. For example, if the fuel cell voltage is detected and the detected voltage is below a preset threshold value, the fuel cell output is stopped or decreased, or the fuel supply amount is increased or the supply gas is humidified. It is only necessary to have a function such as

  The voltage converter is a circuit that adjusts a DC voltage input to the voltage converter and outputs a stabilized voltage, and the stabilized voltage may be a DC voltage or an AC voltage. A voltage converter that outputs a stabilized DC voltage is called a DC-DC converter, and a voltage converter that outputs a stabilized AC voltage is called a DC-AC converter.

  The DC-DC converter only needs to convert the DC voltage of the fuel cell into a DC voltage that does not hinder the operation of the load and supply power to the load. The supply voltage to the load is stabilized and constant. More preferably. For example, a series regulator, a switching regulator, a charge pump, a switched capacitor, etc. are mentioned. Similarly, the DC-AC converter only needs to be able to convert the DC voltage of the fuel cell to an AC voltage that does not hinder the operation of the load and supply electric power to the load, such as a transformer.

  FIG. 1 is a schematic configuration explanatory view showing an example of a fuel cell system according to Embodiment 1 of the present invention.

  As shown in FIG. 1, in the fuel cell system of the first embodiment, a second DC-DC converter of two voltage converters is used for convenience of using a direct current electronic load device as a load of the fuel cell system. 5 was used.

  In the fuel cell system, a PEFC passive fuel cell 1 capable of taking out electric power from a fuel by a chemical reaction was used as a power source. The fuel cell 1 was composed of three cells, and the cells were connected in series. The anode chamber of the three cells of the fuel cell 1 was made common, and a fuel tank 2 storing hydrogen by a hydrogen storage alloy was connected to the anode chamber of the fuel cell 1. One atmosphere of hydrogen was supplied to the anode chamber by a pressure regulator (not shown).

  Both electrodes of the cell having the highest potential electrode among the cells constituting the fuel cell 1 were connected to the input of the second DC-DC converter 5. The second DC-DC converter 5 is a charge pump type booster circuit using fully depleted SOI technology, and starts boosting when the input voltage is 0.3 V or higher. The second DC-DC converter 5 is boosted to a voltage of +2.4 V with reference to the negative pole of the cell to which the second DC-DC converter 5 is connected, and a maximum of +4.2 V with respect to the ground potential of the fuel cell system. did.

  The fuel cell protection means 3 includes a power source from the second DC-DC converter 5 or the first DC-DC converter 4 and a DC-DC converter having a high voltage by a diode OR composed of a Schottky diode 9 and a Schottky diode 10. Is supplied to the power supply terminal 7.

  Although the detailed configuration of the fuel cell protection means 3 is not shown in the figure, the voltage of the three cells constituting the fuel cell 1 is detected using three voltage detectors, and the output of the voltage detector when the cell becomes 0.3 V or less. Change the signal. The output of the voltage detector is input to a three-input NAND circuit, and when at least one cell becomes 0.3 V or less, the output signal of the three-input NAND circuit is used as a signal of the fuel cell protection means 3, and the status signal A signal indicating power generation abnormality is generated from the output terminal 8. The output signal of the status signal output terminal 8 generates an L level signal at the time of power generation abnormality when at least one cell becomes 0.3 V or less and when the fuel cell protection means 3 is not in operation. An H level signal is generated only when all the constituent cells are normal.

  The first DC-DC converter 4 receives the output of the fuel cell 1 and supplies power to an external load. The output voltage of the first DC-DC converter 4 was set to 5.0V. The maximum output of the first DC-DC converter 4 was 3.0 W, and the conversion efficiency of the first DC-DC converter 4 was about 80%.

  Although not shown, the power at the time of starting the first DC-DC converter 4 may be obtained from the second DC-DC converter. At this time, the power supply of the first DC-DC converter is input to the power supply input of the first DC-DC converter by inputting the output of the second DC-DC converter and the output of the first DC-DC converter with a diode OR. The input can be easily switched.

  The first DC-DC converter 4 is configured to start operation when an H level signal is input from the fuel cell protection means 3 to the state signal input terminal 12.

  The operating voltage of the first DC-DC converter 4 was 1.8 to 5.5 V, and the secondary output of its own was fed back to the power source of the first DC-DC converter 4.

  The output of the first DC-DC converter 4 was input to the operation switching signal input terminal 11 of the second DC-DC converter 5. The second DC-DC converter 5 is configured to stop the operation when the input voltage of the operation switching signal input terminal 11 is higher than the threshold voltage for stopping its own operation. The threshold voltage this time was set to 4.3V.

  FIG. 2 is a flowchart showing an example of the flow of operation of the fuel cell system according to Embodiment 1 of the present invention. Here, the operation at the start of the fuel cell system shown in FIG. 1 will be described.

First, when supply of hydrogen as a fuel to the fuel cell 1 is started (step S1), an electromotive voltage is generated in the fuel cell 1, and a potential difference is generated at the output terminal of the fuel cell 1 (step S2).
The signal output from the state signal output terminal 8 of the fuel cell protection means 3 is L level when no power is supplied to the fuel cell protection means 3 (step S3), and an electromotive voltage is generated in the fuel cell 1. However, the first DC-DC converter 4 does not start in the state where the L level signal is input to the first DC-DC converter 4.

  When the voltage of one cell of the three cells of the fuel cell 1 to which the second DC-DC converter 5 is connected becomes 0.3 V or higher, the second DC-DC converter 5 starts boosting ( Step S4).

  When the output voltage of the second DC-DC converter 5 outputs a boosted voltage of +2.4 V with reference to the negative pole of the cell connected to the second DC-DC converter 5, the fuel cell protection means 3 operates. (Step S5).

  When the fuel cell protection means 3 operates, the cell voltage of the fuel cell 1 is detected (step S6). When all the cells become 0.3 V or more, the process proceeds to the next step S7, and an H level signal is output from the state signal output terminal 8 of the fuel cell protection means 3 (step S7).

  When an H level signal is input to the first DC-DC converter 4 from the state signal output terminal 8 of the fuel cell protection means 3, the first DC-DC converter starts to operate (step S8).

  When the first DC-DC converter 4 is operated, a voltage of 5.0 V is obtained from the first DC-DC converter. Therefore, the power supply to the fuel cell protection means 3 is switched from the supply from the second DC-DC converter 5 to the supply from the first DC-DC converter 4 by the diode OR of the Schottky diode 9 and the Schottky diode 10. (Step S9). That is, the output of the first DC-DC converter 4 is input to the fuel cell protection means 3.

  When the first DC-DC converter 4 is operated, 5.0 V is input to the operation switching signal input terminal 11 of the second DC-DC converter 5. At this time, when the voltage input to the operation switching signal input terminal 11 is 4.3 V or higher, the operation of the second DC-DC converter is stopped because the operation of itself is stopped (step S10).

  In step S11, the fuel cell protection means 3 detects all cell voltages constituting the fuel cell 1, and if at least one cell voltage is 0.3 V or less, the operation of the first DC-DC converter is performed. (Step S13), the fuel supply is stopped, and the operation of the fuel cell system is terminated. On the other hand, in step S11, the fuel cell protection means 3 detects all the cell voltages constituting the fuel cell 1, and if all the cell voltages are 0.3 V or higher, the fuel supply is stopped (step S12). ), The process of step S11 is performed, and the fuel cell protection means 3 continues to detect all the cell voltages constituting the fuel cell 1.

  In step S12, when the fuel supply is stopped, the operation of the fuel cell system is stopped.

  Although not described in the flow here, the output characteristics of the fuel cell are improved by performing conditioning and warm-up of the fuel cell between the steps S4 and S5.

  FIG. 3 is a schematic configuration diagram illustrating an example of a fuel cell system according to Embodiment 2 of the present invention. In FIG. 3, the same components as those included in the fuel cell system in Embodiment 1 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted below.

  In the element used in the fuel cell protection means 3 shown in Example 1 of the present invention, an electronic element having a minimum drive voltage of 1.8 V was used, so that it could not operate with the output of the fuel cell. Therefore, in the first embodiment, the second DC-DC converter 5 is used. However, when all the electronic elements constituting the fuel cell protection means 3 are operable only by the output of the fuel cell, the second DC-DC converter 5 is used. Without using the DC-DC converter 5, it is possible to obtain the same effect as that of the first embodiment, for example, by the configuration shown in FIG.

  FIG. 4 is a flowchart showing an example of the flow of operation of the fuel cell system according to Embodiment 2 of the present invention. Here, the operation at the start of the fuel cell system shown in FIG. 3 will be described.

First, when hydrogen as a fuel is supplied to the fuel cell 1 (step S21), a potential difference is generated at the output terminal of the fuel cell 1 (step S22).
The signal output from the state signal output terminal 8 of the fuel cell protection means 3 is at L level when no power is supplied to the fuel cell protection means 3 (step S23), and an electromotive voltage is generated in the fuel cell 1. However, the first DC-DC converter 4 does not start in the state where the L level signal is input to the first DC-DC converter 4.

  Among the cells constituting the fuel cell 1, one cell having the ground potential of the fuel cell 1 as the negative terminal of the cell is connected to the power supply terminal 7 of the fuel cell protection means 3 to supply power to the fuel cell protection means. When the fuel cell protection means 3 operates (step S24), the cell voltage of the fuel cell 1 is detected (step S25). The process of step S6 is performed until all the cells become 0.3V or more. When all the cells become 0.3V or more, the process proceeds to the next step S26, and the state signal output terminal 8 of the fuel cell protection means 3 An H level signal is output (step S26).

  When an H level signal is input to the first DC-DC converter 4 from the state signal output terminal 8 of the fuel cell protection means 3, the first DC-DC converter starts to operate (step S27).

  When the first DC-DC converter 4 is operated, a voltage of 5.0 V is obtained from the first DC-DC converter. Accordingly, the power supply to the fuel cell protection means 3 is switched from the supply from one cell of the fuel cell 1 to the supply from the first DC-DC converter 4 by the diode OR of the Schottky diode 9 and the Schottky diode 10. (Step 28). That is, the output of the first DC-DC converter 4 is input to the fuel cell protection means 3.

  In step S29, the fuel cell protection means 3 detects all the cell voltages constituting the fuel cell 1, and if at least one cell voltage is 0.3 V or less, the first DC-DC converter The operation is stopped (step S31), the fuel supply is stopped, and the operation of the fuel cell system is ended. On the other hand, in step S29, the fuel cell protection means 3 detects all the cell voltages constituting the fuel cell 1, and if all the cell voltages are 0.3 V or higher, the fuel supply is stopped (step S29). S30), the process of step S29 is performed, and the fuel cell protection means 3 continues to detect all the cell voltages constituting the fuel cell 1.

  In step S30, when the fuel supply is stopped, the operation of the fuel cell system is stopped.

  FIG. 5 is a schematic configuration explanatory view showing an example of a fuel cell system according to Embodiment 3 of the present invention. Here, components similar to those included in the fuel cell system in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 5, the fuel cell system according to the third embodiment is similar to the fuel cell system according to the second embodiment. When the fuel cell protection means 3 can operate only with the electric power of the fuel cell, the fuel cell system The battery 1 can be operated using the electric power of the cell fuel battery 13 of a different system from the battery 1.

  Similarly, as shown in FIG. 5, the output of a cell fuel cell of a system different from the fuel cell 1 is input to the second DC-DC converter, and the fuel cell is output using the output of the second DC-DC converter. It is also possible to activate the first DC-DC converter by operating the protection means.

  FIG. 6 is a schematic configuration explanatory view showing an example of a fuel cell system according to Embodiment 4 of the present invention. Here, the same code | symbol is attached | subjected about the same component contained in the fuel cell system demonstrated in Examples 1-3, and the detailed description is abbreviate | omitted.

  As shown in FIG. 6, the second DC-DC converter 5 in the present embodiment has a connection configuration in which power is supplied from an independent cell 13 different from the fuel cell 1 in which the cells are connected in series. The output of the second DC-DC converter 5 is input to the power supply terminal 7 of the fuel cell protection means 3 via the Schottky diode 9 so that the fuel cell protection means 3 can be activated and driven. Since the Schottky diode 9 and the Schottky diode 10 form a diode OR and the output is input to the power supply terminal 7 of the fuel cell protection means 3, the DC-DC converter that supplies power to the fuel cell protection means 3 is The DC-DC converter is connected to the Schottky diode having the higher voltage input to the anode of each Schottky diode.

  Here, when the supply of fuel to the fuel cell 1 and the cell 13 was started, an electromotive voltage was obtained from the cell 13 and the fuel cell 1. The cell 13 was 0.964V, and the fuel cell 1 was 2.753V. Since the second DC-DC converter 5 can start the operation when the input voltage is 0.3 V or more, the second DC-DC converter 5 starts the operation by the current input from the cell 13 and is 2.38 V. Got the output. This output was input to the fuel cell protection means 3 via the Schottky diode 9, and the fuel cell protection means 3 operated. Since the battery voltages of the cells of the fuel cell 1 were 0.957 V, 0.955 V, and 0.941 V, the first DC-DC converter 4 was connected from the state signal operation force terminal 8 of the fuel cell protection means 3. A signal for starting was output.

  By this signal, the first DC-DC converter 4 starts operation, and the voltage of 5.02 V in the vicinity of the preset output voltage value of 5.00 V is set to the first DC-DC from the output of the fuel cell 1 as a source. Obtained on the output side (secondary side) of the converter 4. This output is connected to the fuel cell protection means 3 via the Schottky diode 10. Since the output voltage of the first DC-DC converter 4 is 5.02 V with respect to the output voltage of 2.38 V of the second DC-DC converter 5, after the first DC-DC converter 4 is started, The output of the first DC-DC converter 4 is input to the power supply terminal 7 of the fuel cell protection means 3. Since the measured value of the input voltage of the power terminal 7 was 4.67 V, it was confirmed that the output of the first DC-DC converter was input to the power terminal 7. The output of the first DC-DC converter 4 is input to the operation switching signal input terminal 11 of the second DC-DC converter 5 via the delay circuit 14. Although the circuit configuration is not illustrated, the delay circuit 14 is configured by a delay circuit using a CR circuit and a pull-down circuit.

  In the pull-down circuit, the connection line with the constant operation switching signal input terminal 11 is connected to GND via a resistor, the first DC-DC converter 4 is activated, and the output of the first DC-DC converter 4 is output. When input to the delay circuit 14, the operation switching signal input terminal 11 and the first DC-DC converter 4 are connected. The delay circuit 14 delays the output to the operation switching signal input terminal 11 according to the set time constant of the CR circuit.

  The second DC-DC converter 5 stops its own operation when the output after the activation of the first DC-DC converter 4 is input to the operation switching signal input terminal 11, and minimizes power consumption. This reduces the fuel consumption of the cell 13. Since the fuel cell protection means 3 always operates and can monitor the output state of the fuel cell 1 until the first DC-DC converter 4 is started and the second DC-DC converter 5 is stopped. When there is an abnormality in the output of the cells constituting the battery, the operation of the first DC-DC converter 4 can be stopped immediately. Therefore, it is possible to prevent deterioration even when the fuel cell 1 is started, and the life and long-term reliability of the fuel cell system are improved.

  Here, the fuel cell is configured to have three cells connected in series. However, the present invention is not particularly limited to this, and the number of cells constituting the fuel cell can be freely selected.

  Since the fuel cell system of the present invention prevents the fuel cell from operating in an overloaded state, it is possible to prevent corrosion of the fuel cell and deterioration of output characteristics. Prevention of power generation in the deterioration mode of the fuel cell and the initial power generation capability of the fuel cell are maintained, and stable power supply is possible. Since a simple configuration is possible, it can be applied to miniaturization of a fuel cell system for portable devices.

BRIEF DESCRIPTION OF THE DRAWINGS It is schematic structure explanatory drawing which shows the example of the fuel cell system which concerns on Example 1 of this invention. It is a flowchart which shows an example of the flow of operation | movement of the fuel cell system which concerns on Example 1 of this invention. It is schematic structure explanatory drawing which shows the example of the fuel cell system which concerns on Example 2 of this invention. It is a flowchart which shows an example of the flow of operation | movement of the fuel cell system which concerns on Example 2 of this invention. It is schematic structure explanatory drawing which shows the example of the fuel cell system which concerns on Example 3 of this invention. It is schematic structure explanatory drawing which shows the example of the fuel cell system which concerns on Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel tank 3 Fuel cell protection means 4 1st DC-DC converter 5 2nd DC-DC converter 6 Load 7 Power supply terminal 8 Status signal output terminal 9 Schottky diode 10 Schottky diode 11 Operation switching signal input terminal 12 Status signal input terminal 13 Cell 14 Delay circuit

Claims (17)

A fuel cell comprising a plurality of cells that generate power by supplying fuel, a fuel cell protection means for protecting the fuel cell, and one or more voltage converters that receive the output of the fuel cell as input, The fuel cell protection means operates by receiving power supply from at least one of the fuel cell and the voltage converter, and in the starting method of the fuel cell system for supplying the output power of the voltage converter to a load,
Operating the fuel cell protection means using the output of one of the cells constituting the fuel cell as a source after starting the supply of fuel to the fuel cell at the time of starting the fuel cell system;
Starting the voltage converter based on a signal transmitted by the fuel cell protection means after the fuel cell protection means operates;
Switching power supply to the fuel cell protection means to the output of the voltage converter after the voltage converter is operating;
A method for starting a fuel cell system comprising:   In the fuel cell, at least a part or all of a plurality of cells are connected in series, and the cell that supplies power to the fuel cell protection means when the fuel cell system is started up is the fuel connected in series. 2. The method for starting a fuel cell system according to claim 1, wherein the cell is a single cell having a ground potential electrode of the cell as a negative electrode of the cell.   In the fuel cell, at least a part or all of a plurality of cells are connected in series, and one cell that supplies power to the fuel cell protection means when the fuel cell system is started up is the most with respect to the ground potential. The method for starting a fuel cell system according to claim 1, wherein the cell is one cell out of cells having positively large potential difference or most negatively large potential difference.   In the fuel cell, some of a plurality of cells are connected in series, and a cell that supplies power to the fuel cell protection means when the fuel cell system is started is a cell constituting the series connection. The method for starting a fuel cell system according to claim 1, wherein the cells are different cells. A fuel cell composed of a plurality of cells that generate power by supplying fuel, a fuel cell protection means for protecting the fuel cell, a first voltage converter that receives the output of the fuel cell, and a second A voltage converter, wherein the fuel cell protection means receives power from at least one of the second voltage converter, the first voltage converter, or the fuel cell, and the first voltage converter In the starting method of the fuel cell system for supplying the output power of
When starting the fuel cell system, operating the second voltage converter using the output of one of the cells constituting the fuel cell after the start of fuel supply to the fuel cell;
After starting the second voltage converter, operating the fuel cell protection means using the output of the second voltage converter;
Starting the first voltage converter based on a signal transmitted by the fuel cell protection means after the fuel cell protection means is operated;
Switching the power supply to the fuel cell protection means from the output of the second voltage converter to the output of the first voltage converter after starting the first voltage converter;
Stopping the operation of the second voltage converter after switching the power supply to the fuel cell protection means from the output of the second voltage converter to the output of the first voltage converter;
A method for starting a fuel cell system comprising:   In the fuel cell, some or all of a plurality of cells are connected in series, and when the fuel cell system is activated, the fuel cell is connected to the second voltage converter and supplies power to the second voltage converter. 6. The method of starting a fuel cell system according to claim 5, wherein the cell to be operated is one cell having a ground potential electrode of the fuel cells connected in series as a negative electrode of the cell.   In the fuel cell, at least some of a plurality of cells are connected in series, and when the fuel cell system is started up, the fuel cell is connected to the second voltage converter and supplies power to the second voltage converter. 6. The start of the fuel cell system according to claim 5, wherein one cell to be supplied is one of cells having an electrode having the largest positive potential difference or an electrode having the largest negative potential difference with respect to the ground potential. Method.   In the fuel cell, at least some of a plurality of cells are connected in series, and when the fuel cell system is activated, the fuel cell system is connected to the second voltage converter and supplies power to the second voltage converter. The method of starting a fuel cell system according to claim 5, wherein one cell to be supplied is one cell different from the cells constituting the series connection. A fuel cell composed of a plurality of cells that generate electricity by supplying fuel; and
A fuel cell protection means for protecting the fuel cell; and one or more voltage converters using the output of the fuel cell as input.
The power source of the fuel cell protection means receives power from the output of one of the plurality of cells constituting the fuel cell, and the fuel cell protection means distinguishes the output state of the fuel cell. A state signal output terminal for outputting a signal to be output, the state signal output terminal is connected to the voltage conversion device, and the voltage conversion device switches operation based on an input signal from the state signal output terminal, and the fuel A fuel cell system in which the voltage converter is activated after the battery protection means is operated and supplies output power of the voltage converter to a load.   In the fuel cell, at least some of a plurality of cells are connected in series, and the cells that supply power to the fuel cell protection means when the fuel cell system is started up are connected in series. The fuel cell system according to claim 9, wherein the ground potential electrode is a single cell having a negative electrode of the cell.   In the fuel cell, at least a part or all of a plurality of cells are connected in series, and one cell that supplies power to the fuel cell protection means when the fuel cell system is activated is 10. The fuel cell system according to claim 9, wherein the fuel cell system is one of the cells having the electrode having the largest positive potential difference or the electrode having the largest negative potential difference.   In the fuel cell, at least some of a plurality of cells are connected in series, and a cell that supplies electric power to the fuel cell protection means when the fuel cell system is activated includes a cell constituting the series connection. The fuel cell system according to claim 9, wherein is a different cell. A fuel cell composed of a plurality of cells that generate electricity by supplying fuel; and
Fuel cell protection means for protecting the fuel cell;
A first voltage converter that receives the output of the fuel cell;
A second voltage converter;
With
One of the plurality of cells constituting the fuel cell is connected to the input of the second voltage converter, and the fuel cell protection means outputs a signal for distinguishing the output state of the fuel cell A signal output terminal, wherein the state signal output terminal is connected to the first voltage converter, and the first voltage converter switches operation based on an input signal from the state signal output terminal, and the fuel A fuel cell system in which the first voltage conversion device is activated based on a signal transmitted from the fuel cell protection device after the battery protection device is operated, and supplies output power of the first voltage conversion device to a load.   In the fuel cell, at least some of a plurality of cells are connected in series, and when the fuel cell system is started, the cells that supply power to the second voltage converter are connected in series. 14. The fuel cell system according to claim 13, wherein the fuel cell system is one cell having a ground potential electrode of the fuel cell as a negative electrode of the cell.   In the fuel cell, some or all of a plurality of cells are connected in series, and one cell that supplies power to the second voltage converter when the fuel cell system is started is connected to a ground potential. 14. The fuel cell system according to claim 13, wherein the fuel cell system is one cell having an electrode having the largest positive potential difference or an electrode having the largest negative potential difference.   In the fuel cell, some of the plurality of cells are connected in series, and one cell that supplies power to the second voltage conversion device at the time of startup of the fuel cell system constitutes the series connection. The fuel cell system according to claim 13, wherein the fuel cell system is one cell different from the cell.   The second voltage converter has an operation switching signal input terminal, and the operation of the second voltage converter is switched by a signal input to the operation switching signal input terminal. The fuel cell system according to claim 16.

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