JP2009064666A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of supplying certainly pump drive power at the time of power generation without connecting to an external power system. <P>SOLUTION: An auxiliary battery 40, a power storage part 30, and a constant voltage circuit 20 are connected to a power supply selection part 50. The power supply selection part 50 outputs, as a drive voltage of a pump 13 or the like and as an output voltage VD of a fuel cell system, the largest one out of the output voltage VA of the auxiliary battery 40, the output voltage VB of the power storage part 30, and the output voltage VC of the constant voltage circuit 20. Even when power is not stored in the power storage part 30 due to some reasons at the time of power generation start, power is supplied from the auxiliary battery 40 to the pump 13 or the like, and starting of power generation becomes possible. When the output voltage VC of the constant voltage circuit 20 is higher than the output voltage VB of the power storage part 30, the power supply selection part 50 makes the output power from the constant voltage circuit 20 stored in the power storage part 30 through a route B2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high-power fuel cell system that supplies fuel to a power generation unit using a pump, and more particularly to a fuel cell system suitable as a power supply device for a portable electronic device.

A high-power fuel cell system usually includes a pump for sending fuel from a fuel tank to a power generation unit. In addition, power is stored in advance in a separately prepared power storage device, and pump drive power until power generation is supplied from this power storage device, and when power generation starts, power is stored in the power storage device.
JP 2004-171973 A (paragraph 0013)

  However, with this method, there is a problem in that when the power is not stored in the power storage device for some reason, the pump cannot be driven and power generation cannot be started.

  Incidentally, in Patent Document 1, when it is determined that the power generated by the fuel cell is insufficient and the power to be supplied to the load is insufficient, the switching control for switching the grid-connected inverter to supply power from the system power supply to the load. A fuel cell power generation system including means has been proposed. However, since this system power supply is a commercial power supply and needs to be connected to an external power system, it is not suitable for application to portable electronic devices.

  The present invention has been made in view of such problems, and an object thereof is to provide a fuel cell system that can reliably supply pump drive power at the start of power generation without connection to an external power system. is there.

  The fuel cell system of the present invention has no connection to an external power system, and includes a power generation unit constituted by a fuel cell that receives fuel supplied from a fuel tank by a pump, and a constant voltage connected to the power generation unit. A circuit, a power storage unit capable of storing the power generated by the power generation unit, an auxiliary battery, and a power source selection unit connected to the auxiliary battery, the power storage unit, and the constant voltage circuit. The largest output voltage, the output voltage of the power storage unit, and the output voltage of the constant voltage circuit are output as the drive voltage of the pump and the output voltage of the fuel cell system.

  In the fuel cell system of the present invention, the output voltage of the auxiliary battery, the output voltage of the power storage unit, and the output voltage of the constant voltage circuit enter the power source selection unit, and the largest one of them is the pump drive voltage and the fuel cell system. Output as output voltage. At the start of power generation, if the output voltage of the constant voltage circuit connected to the power generation unit is low and no power is stored in the power storage unit for some reason, the output voltage of the auxiliary battery is the output voltage of the power source selection unit It is said. Therefore, electric power necessary for driving the pump is supplied from the auxiliary battery, fuel is sent from the fuel tank to the power generation unit, and power generation is started.

  According to the fuel cell of the present invention, the auxiliary battery is connected to the power source selection unit, and the power source selection unit has the largest one of the output voltage of the auxiliary battery, the output voltage of the power storage unit, and the output voltage of the constant voltage circuit. Is output as the pump drive voltage and the output voltage of the fuel cell system, the pump drive power at the start of power generation can be reliably supplied without connection to an external power system. Therefore, it is particularly suitable for a fuel cell system mounted on a portable electronic device, and the convenience of the device can be improved.

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

  FIG. 1 shows a configuration of a fuel cell system according to an embodiment of the present invention. This fuel cell system is used, for example, as a power supply device for mobile devices such as mobile phones and PDAs (Personal Digital Assistants), or portable electronic devices such as notebook PCs (Personal Computers). The power generation unit 10, the constant voltage circuit 20, the power storage unit 30, the auxiliary battery 40, and the power source selection unit 50 are included.

  The power generation unit 10 generates power by receiving a fuel tank 11 containing liquid fuel (for example, methanol water), a pump 13 connected to the fuel tank 11 via a connector 12, and fuel supplied by the pump. A fuel cell 14 and an air blower (fan) 15 for supplying air to the fuel cell 14 are provided. The blower 15 may be provided as necessary, and may be omitted depending on the configuration of the fuel cell 14, and air, that is, oxygen may be supplied by natural ventilation.

The fuel cell 14 has, for example, a configuration in which a plurality of unit cells are electrically connected in series. Each unit cell is a direct methanol fuel cell that generates electric power by reaction of methanol and oxygen, and has a fuel electrode and an oxygen electrode that are arranged to face each other with an electrolyte therebetween (both not shown). ). The electrolyte may be, for example, an electrolytic solution that is a liquid electrolyte, that is, a fluid having a fluidity such as sulfuric acid or a gel, or an electrolyte membrane made of a proton conductive material having a sulfonic acid group (—SO ₃ H). In addition, as the proton conductive material, polyperfluoroalkylsulfonic acid proton conductive material (for example, “Nafion (registered trademark)” manufactured by DuPont), hydrocarbon proton conductive material such as polyimide sulfonic acid, or fullerene proton conductive material. Materials and the like. The fuel electrode and the oxygen electrode have a configuration in which a catalyst layer containing a catalyst such as platinum (Pt) or ruthenium (Ru) is formed on a current collector made of, for example, carbon paper. The catalyst layer is made of, for example, a dispersion in which a carrier such as carbon black carrying a catalyst is dispersed in a polyperfluoroalkylsulfonic acid proton conductive material or the like. In addition, the air blower 15 mentioned above is connected to the oxygen electrode.

  The constant voltage circuit 20 generates a predetermined constant voltage based on the electromotive voltage in the power generation unit 10, and supplies power to the pump 13 and the blower 15 based on the constant voltage. For example, the DC / DC It is composed of a converter.

  The power storage unit 30 stores power generated by the power generation unit 10 and supplies power to the pump 13 and the blower 15 at the start of power generation. The power storage unit 30 includes, for example, a secondary battery or a capacitor. Yes. Examples of the secondary battery include a general storage battery such as a nickel / cadmium storage battery or a nickel / hydrogen storage battery, or a lithium ion secondary battery.

  The auxiliary battery 40 has a function as an auxiliary power source when electric power is not stored in the power storage unit 30 for some reason, and is configured by, for example, a primary battery or a secondary battery. Examples of the primary battery include a manganese dry battery or an alkaline manganese battery, and examples of the secondary battery include a lithium ion secondary battery.

  It is preferable that the fuel tank 11 and the auxiliary battery 40 constitute one module 60 and be removable from the other parts of the fuel cell system. This is because the convenience of handling, such as replacement of the fuel tank 11, replenishment of liquid fuel, replacement of the auxiliary battery 40, and charging when the auxiliary battery 40 is a secondary battery, can be improved. It is desirable that the auxiliary battery 40 has a shape that matches the shape of the button-type battery or the module 60 from the viewpoint of miniaturization of the fuel cell system. Any shape is acceptable.

  The power source selection unit 50 is connected to the auxiliary battery 40, the power storage unit 30, and the constant voltage circuit 20, and is connected to an external device body (load) (not shown) via the output terminal 70. The power source selection unit 50 uses the highest output voltage VA of the auxiliary battery 40, the output voltage VB of the power storage unit 30 and the output voltage VC of the constant voltage circuit 20 as the drive voltage of the pump 13 and the output of the entire fuel cell system. The voltage is VD. Thereby, in this fuel cell system, the drive power of the pump 13 at the start of power generation can be reliably supplied without connection to an external power system.

  Further, when the output voltage VC of the constant voltage circuit 20 is higher than the output voltage VB of the power storage unit 30, the power source selection unit 50 stores the output power from the constant voltage circuit 20 in the power storage unit 30 (path B2 in FIG. 1). ). When the output voltage VC of the constant voltage circuit 20 is lower than the output voltage VB of the power storage unit 30, the power storage unit 30 is not charged.

  When the output voltage VC of the constant voltage circuit 20 is smaller than the output voltage VA of the auxiliary battery 50, the power source selection unit 50 outputs the voltage VD only to the pump 13 or the blower 15 so that the entire fuel cell system It is desirable to stop the output (output of the output terminal 70). Therefore, for example, a switch 71 is provided between the output terminal 70, the pump 13, and the blower 15, and when the output voltage VC of the constant voltage circuit 20 is smaller than the output voltage VA of the auxiliary battery 50, the switch 71 is turned off. It is desirable to stop the output of the entire fuel cell system in a state. Further, it is desirable to provide a circuit (not shown) for preventing chattering at the time of switching by the switch 71.

  FIG. 2 shows a configuration example of the power supply selection unit 50. The power supply selection unit 50 includes, for example, an npn transistor 51, diodes 52, 53, and 54, and a resistance element 55. The collector of the npn transistor 51 is connected to the terminal C on the constant voltage circuit 20 side. The base of the npn transistor 51 is connected to the cathode of the diode 52 through the resistance element 55. The emitter of the npn transistor 51 is connected to the terminal B on the power storage unit 30 side, the anode of the diode 52, and the anode of the diode 53. The cathode of the diode 53 is connected to the terminal D on the power source selection unit 50 side and the cathode of the diode 54. The anode of the diode 54 is connected to the terminal A on the auxiliary battery 40 side.

  In this fuel cell system, in each power generation unit 10, liquid fuel is supplied from the fuel tank 13 to the fuel electrode of the fuel cell 14, and protons and electrons are generated by the reaction. Protons move through the electrolyte to the oxygen electrode and react with electrons and oxygen to produce water. Thereby, a part of chemical energy of the liquid fuel, that is, methanol is converted into electric energy and taken out as an electric current.

  FIG. 3 is a diagram for explaining the operation of the power supply selection unit 50. First, when power is not stored in the power storage unit 30 for some reason at the start of power generation, the output voltage VA of the auxiliary battery 40 is greater than the output voltage VB of the power storage unit 30 and the output voltage VC of the constant voltage circuit 20. (VA> VB, VC). In this case, the power supply selection unit 50 outputs (selects) the output voltage VA of the auxiliary battery 40 as the drive voltage VD of the pump 13. Therefore, even when power is not stored in the power storage unit 30, the driving power of the pump 13 and the blower 15 is supplied from the auxiliary battery 40, and the power generation unit 10 can start power generation. At this time, since the output voltage VC of the constant voltage circuit 20 is smaller than the output voltage VA of the auxiliary battery 40, the switch 71 is set to the OFF state by the power source selection unit 50, and the voltage VD is externally supplied via the output terminal 70. Is not supplied to the main unit.

  On the other hand, when power is sufficiently stored in power storage unit 30 at the start of power generation, output voltage VB of power storage unit 30 is larger than output voltage VA of auxiliary battery 40 and output voltage VC of constant voltage circuit 20. (VB> VA, VC). In this case, the power supply selection unit 50 outputs (selects) the output voltage VB of the power storage unit 30 as the drive voltage VD of the pump 13 (path B1 in FIG. 1). Accordingly, the drive power of the pump 13 and the blower 15 is supplied from the power storage unit 30, and the power generation of the power generation unit 10 can be started. At this time, the switch 71 is set to the on state or the off state by the power source selection unit 50 in accordance with the magnitude relationship between the output voltage VC of the constant voltage circuit 20 and the output voltage VA of the auxiliary battery 40. When the switch 71 is on, the voltage VD is supplied to the external device body via the output terminal 70. When the switch 71 is in the OFF state, the voltage VD is supplied only to the pump 13 and the blower 15 and the output of the entire fuel cell system is stopped.

  When power generation in the power generation unit 10 is started in this way, the output voltage VC of the constant voltage circuit 20 becomes larger than the output voltage VA of the auxiliary battery 40 and the output voltage VB of the power storage unit 30 (VC> VA, VB). In this case, the power supply selection unit 50 outputs (selects) the output voltage VC of the constant voltage circuit 20 as the drive voltage of the pump 13 and the output voltage VD of the entire fuel cell system. Therefore, the electric power generated by the power generation unit 10 is supplied to the pump 13 and the blower 15. At this time, since the output voltage VC of the constant voltage circuit 20 is larger than the output voltage VA of the auxiliary battery 40, the switch 71 is set to the ON state by the power source selection unit 50, and the voltage VD is externally supplied via the output terminal 70. It is also supplied to the equipment body.

  Further, when the output voltage VC of the constant voltage circuit 20 is higher than the output voltage VB of the power storage unit 30 (VC> VB), the power source selection unit 50 uses the terminal C → terminal B (path B2 in FIG. 1). Then, the output power from the constant voltage circuit 20 is stored in the power storage unit 30. On the other hand, when the output voltage VB of the power storage unit 30 is higher than the output voltage VC of the constant voltage circuit 20 (VB> VC), the power storage unit 30 is not charged. When output voltage VC of constant voltage circuit 20 is equal to output voltage VB of power storage unit 30 (VC = VB), output voltage VC of constant voltage circuit 20 is greater than output voltage VB of power storage unit 30. The case can be the same as the case (VC> VB) and the case where the output voltage VB of the power storage unit 30 is higher than the output voltage VC of the constant voltage circuit 20 (VB> VC).

  Thus, in the present embodiment, auxiliary battery 40, power storage unit 30 and constant voltage circuit 20 are connected to power supply selection unit 50, and output voltage VA of auxiliary battery 40, output voltage VB of power storage unit 30 and constant voltage circuit 20 are constant. Since the largest output voltage VC of the voltage circuit 20 is set as the output voltage VD of the power supply selection unit 50, the drive power of the pump 13 and the like at the start of power generation can be ensured without connection to the external power system. Can be supplied. Therefore, it is particularly suitable for a fuel cell system mounted on a portable electronic device, and the convenience of the device can be improved.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the material and thickness of each component described in the above embodiment or the power generation conditions of the fuel cell are not limited, and may be other materials and thicknesses, or may be other power generation conditions. For example, the liquid fuel may be methanol or other liquid fuel such as ethanol or dimethyl ether.

  The fuel cell system according to the present invention includes, for example, a mobile phone, an electronic photographer, an electronic notebook, a notebook personal computer, a camcorder, a portable game machine, a portable video player, a headphone stereo, or a PDA (Personal Digital Assistants). It can be suitably used for a type of electronic device.

It is a figure showing the structure of the fuel cell system which concerns on one embodiment of this invention. FIG. 2 is a circuit diagram illustrating an example of a power supply selection unit illustrated in FIG. 1. It is a figure for demonstrating an effect | action of the power supply selection part shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Power generation part, 20 ... Constant voltage circuit, 30 ... Power storage part, 40 ... Auxiliary battery, 50 ... Power supply selection part

Claims (4)

A fuel cell system having no connection to an external power system,
A power generation unit composed of a fuel cell that receives fuel from a fuel tank by a pump;
A constant voltage circuit connected to the power generation unit;
A power storage unit capable of storing power generated by the power generation unit;
An auxiliary battery,
A power source selection unit connected to the auxiliary battery, the power storage unit and the constant voltage circuit,
The power supply selection unit outputs the highest one of the output voltage of the auxiliary battery, the output voltage of the power storage unit, and the output voltage of the constant voltage circuit as the drive voltage of the pump and the output voltage of the fuel cell system. A fuel cell system. The power supply selection unit causes the power storage unit to store output power from the constant voltage circuit when an output voltage of the constant voltage circuit is higher than an output voltage of the power storage unit. Fuel cell system. 3. The fuel cell system according to claim 1, wherein the fuel tank and the auxiliary battery constitute one module that is removable from other parts of the fuel cell system. 4. The fuel cell system according to any one of claims 1 to 3, wherein the auxiliary battery is a primary battery or a secondary battery, and the power storage unit is a secondary battery or a capacitor.

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