JP2010287534A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of reducing a load of a secondary battery, even when large electric power is required for a fuel cell, in a state of applying electric power restriction to a converter by heat. <P>SOLUTION: The fuel cell system 1 includes: the fuel cell 10 for generating electric power by electrochemical reaction of an anode gas and cathode gas; the secondary battery 12 capable of charging and discharging; an auxiliary machine 14 driven by the electric power from the fuel cell 10 or the secondary battery 12; a voltage converter 16 arranged between the fuel cell 10 and the auxiliary machine 14; and a restricting means for restricting the electric power required for the fuel cell 12 when passable electric power of passing through the voltage converter 16 is less than maximum electric power consumed by the auxiliary machine 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control technique for a fuel cell system.

  2. Description of the Related Art Generally, a fuel cell system mounted on a vehicle or the like includes a fuel cell that generates electricity by an electrochemical reaction between an anode gas (for example, hydrogen gas) and a cathode gas (for example, air), and a chargeable / dischargeable secondary battery. .

  Usually, in such a fuel cell system, power to a load such as a motor and power to an auxiliary machine necessary for power generation of the fuel cell are supplied from the fuel cell. However, when the converter provided between the fuel cell and the auxiliary device is restricted due to heat or the like, power to the auxiliary device is supplied from the secondary battery.

  In such a state, when a large amount of power is required for the fuel cell, the output of the fuel cell increases and the power consumed by the auxiliary equipment required for power generation of the fuel cell also increases. The burden of increases. Therefore, when the above state continues, there is a problem that the SOC of the secondary battery is quickly reduced.

  Patent Document 1 discloses a technique for appropriately controlling the SOC of a secondary battery in a fuel cell system mounted on a vehicle.

JP 2005-304179 A

  An object of the present invention is to provide a fuel cell system capable of reducing the burden on a secondary battery even when a large amount of power is required for the fuel cell in a state where the power is limited to the converter by heat. .

  A fuel cell system according to the present invention includes a fuel cell that generates electricity by an electrochemical reaction between an anode gas and a cathode gas, a chargeable / dischargeable secondary cell, and an auxiliary device that is driven by the fuel cell or power from the secondary cell. And a voltage converter provided between the fuel cell and the auxiliary machine, and a power that can pass through the voltage converter is less than the maximum power consumed by the auxiliary machine, the request is made to the fuel cell. Limiting means for limiting the power to be generated.

  In the fuel cell system, the power required for the fuel cell is controlled by the control unit so that the fuel is within a limiting rate obtained by passing power passing through the voltage converter / maximum power consumed by the auxiliary machine. It is preferably limited to a value obtained by multiplying the power value required for the battery.

  The fuel cell system of the present invention is driven by a fuel cell that generates electricity by an electrochemical reaction between an anode gas and a cathode gas, a chargeable / dischargeable secondary battery, and power from the fuel cell or the secondary battery. When the auxiliary machine, the voltage converter provided between the fuel cell and the auxiliary machine, and the passable power passing through the voltage converter are less than the maximum power consumed by the auxiliary machine, the auxiliary machine Control means for controlling the power consumed by the power to be equal to or lower than the passable power passing through the voltage converter.

  According to the present invention, the burden on the secondary battery can be reduced even when a large amount of power is required for the fuel cell in a state where the power is limited to the converter by heat.

FIG. 1 is a schematic diagram showing an example of a configuration of a fuel cell system according to an embodiment of the present invention. (A) is a figure which shows the relationship between the reactor temperature of a converter, and the limiting rate of electric power which can be passed, (B) is a figure which shows the relationship between the IPM temperature of a converter, and the limiting factor of electric power which can pass. It is a flowchart which shows an example of operation | movement of the fuel cell system which concerns on this embodiment. It is a figure which shows the state of the fuel cell system which concerns on this embodiment. It is a flowchart which shows another example of operation | movement of the fuel cell system which concerns on this embodiment.

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

  FIG. 1 is a schematic diagram showing an example of a configuration of a fuel cell system according to an embodiment of the present invention. As shown in FIG. 1, the fuel cell system 1 includes a fuel cell 10, a secondary battery 12 configured by a chargeable / dischargeable lithium ion battery, an auxiliary device 14, a fuel cell 10, and an auxiliary device 14. And a converter 16 for stepping up and down the voltage of the fuel cell 10 (or secondary battery 12), and a load 18 such as a motor by converting DC power of the fuel cell 10 (or secondary battery 12) into AC power. And an ECU 20 (control means).

  The converter 16 includes a plurality of switching elements, a reactor, and an IPM (Intelligent Power Module), and boosts or lowers the voltage mainly supplied from the fuel cell 10 to the voltage driven by the auxiliary machine 14 by the on / off operation of the switching elements. is there. The first electric circuit 24 of the converter 16 is connected to the electric circuit on the secondary battery side and the electric circuit on the auxiliary machine side, and the second electric circuit 26 of the converter 16 is connected to the electric circuit on the fuel cell side and the electric circuit on the inverter side. Although specifically described later, normally, when the reactor temperature, the IPM temperature, or the like exceeds a predetermined value, the electric power that can pass through the converter 16 is limited, and the converter 16 may pass through the converter 16. The power that can be generated is reduced or zero.

  The fuel cell 10 is supplied with an anode gas (for example, hydrogen gas) and a cathode gas (for example, air), and generates electricity by an electrochemical reaction between the hydrogen gas and oxygen in the air. The pump supplies the fuel electrode (anode), and the air is supplied to the oxidant electrode (cathode) by an air compressor. Part of the power generated by the fuel cell 10 is supplied to the load 18 (for example, a traveling motor that rotates wheels in a vehicle or the like) through the inverter 20 together with the power of the secondary battery 12 that is stepped up and down by the converter 16. The

  A part of the generated power of the fuel cell 10 passes through the converter 16 and is used for the operation of the fuel cell 10 such as an air compressor, a cooling water pump, and a hydrogen pump, an air conditioner, and a heater. And the like to other high-pressure auxiliary machines (14). In the conventional fuel cell system, when the power that can pass through the converter is limited due to the influence of heating of the converter, etc., the power supply from the fuel cell to the auxiliary device is limited. Supplied from the secondary battery. As a result, the secondary battery 12 is burdened, leading to an early decrease in the SOC of the secondary battery. However, in the present embodiment, even when the power that can be passed through the converter 16 is limited, by limiting the power required for the fuel cell 10, the power consumption of the auxiliary machine 14 is indirectly reduced, and the secondary battery 12. Control to reduce the burden of The specific control of this embodiment will be described later. Further, as described above, in the present embodiment, the power to the auxiliary machine 14 is mainly generated by the power generated by the fuel cell 10, but is supplemented by the secondary battery 12 when the fuel cell 10 is not generating power. Is done.

  The ECU 22 is a computer that includes a CPU that performs signal processing and a storage unit that stores programs and control data. The fuel cell 10, the secondary battery 12, the auxiliary machine 14, the converter 16, the load 18, and the inverter 20 are connected to the ECU 22 and are configured to operate according to commands from the ECU 22.

  The ECU 22 compares the power that can be passed through the converter 16 with the maximum power that the auxiliary device 14 consumes. If the power that can be passed through the converter 16 is less than the maximum power that the auxiliary device 14 consumes, the fuel cell 10 Means for limiting the power required for the system.

  Here, the electric power that can be passed through the converter 16 will be described. FIG. 2A is a diagram showing the relationship between the reactor temperature of the converter and the limit rate of the passable power, and FIG. 2B shows the relationship between the IPM temperature of the converter and the limit rate of the passable power. FIG. As shown in FIGS. 2A and 2B, when the reactor temperature or the IPM temperature of the converter 16 exceeds a predetermined temperature (S1, S3), the limiting rate of the electric power that can be passed through the converter 16 is reduced. The passable power is limited (decreased) (converter power limit rate in FIG. 2 × converter passable power = restricted converter passable power). When the reactor temperature or IPM temperature of converter 16 reaches a predetermined temperature (S2, S4), the limit rate of the power that can be passed through converter 16 becomes zero, the power that can be passed through converter 16 is completely limited, The electric power passing through becomes zero. Then, such data of the electric power that can be passed through the converter 16 is transmitted to the ECU 22. The maximum power consumed by the auxiliary machine 14 is a constant determined by the type, number, capacity, etc. of the auxiliary machine 14 to be used, and is recorded in the ECU 22 in advance.

  In this embodiment, when the ECU 22 determines that the electric power that can be passed through the converter 16 is less than the maximum electric power that the auxiliary machine 14 consumes, the electric power required for the fuel cell 10 is the electric power that can be passed through the converter 16 / It is limited to a value obtained by multiplying the limiting rate obtained by the maximum power consumed by the auxiliary machine 14 by the power value required for the fuel cell 10. In the present embodiment, the fuel cell 10 is not necessarily limited to this, and is required for the fuel cell 10 when the ECU 22 determines that the power that can be passed through the converter 16 is less than the maximum power consumed by the auxiliary machine 14. The power may be limited to a preset value. The power required for the fuel cell 10 includes the power consumed by the load 18, the power consumed by the auxiliary machine 14, the lost power of the converter 16, and the like.

  The operation of the fuel cell system 1 according to this embodiment will be described. FIG. 3 is a flowchart showing an example of the operation of the fuel cell system according to the present embodiment. FIG. 4 is a diagram showing a state of the fuel cell system according to the present embodiment.

  As shown in FIG. 3, first, in step S <b> 10, a signal of the power that can be passed through the converter 16 is input to the ECU 22, and the ECU 22 compares the power that can be passed through the converter 16 with the maximum power consumed by the auxiliary machine 14. The Here, as shown in FIG. 4, when the reactor temperature, the IPM temperature, etc. exceed a predetermined value (S3), the electric power that can be passed through the converter 16 decreases, and when the reactor temperature, the IPM temperature, etc. further exceeds the predetermined value (S3 ′), The available power is lower than the maximum power consumed by the auxiliary machine 14.

  When the passable power of the converter 16 is less than the maximum power consumed by the auxiliary machine 14, the ECU 22 obtains the passable power of the converter 16 / the maximum power consumed by the auxiliary machine 14 in step S12 shown in FIG. The restriction rate to be calculated is calculated. In step S14, the electric power required for the fuel cell 10 is limited by the ECU 22 to a value obtained by multiplying the calculated limiting rate by the electric power value required for the fuel cell 10, and in step S16, the electric power required for the fuel cell 10 Based on this, electric power is output from the fuel cell 10. Here, as shown in FIG. 4, as the reactor temperature, the IPM temperature, and the like rise and the difference between the electric power that can be passed through the converter 16 and the maximum electric power that the auxiliary machine 14 consumes increases, The required power will be limited.

  Thus, by limiting the power required for the fuel cell 10, it is possible to indirectly reduce the power consumption of the auxiliary machine 14 used for the operation of the fuel cell 10. The amount of power supplied to the auxiliary machine 14 can be reduced, and the burden on the secondary battery 12 can be suppressed. Moreover, since the electric power which passes through the converter 16 also decreases by reducing the power consumption of the auxiliary machine 14 as described above, further heating of the converter 16 can be suppressed.

  On the other hand, when the passable power of the converter 16 is equal to or greater than the maximum power consumed by the auxiliary machine 14, the power required for the fuel cell 10 is output as it is without being restricted in step S16.

  Next, another example of the operation of the fuel cell system 1 according to the embodiment of the present invention will be described. Here, the ECU 22 of the fuel cell system 1 according to the present embodiment compares the electric power that can be passed through the converter 16 with the maximum electric power that the auxiliary machine 14 consumes, and the electric power that can be passed through the converter 16 becomes the auxiliary machine 14. When the power consumption is less than the maximum power consumed, the power consumption of the auxiliary machine 14 is limited to a power that can pass through the converter 16 or less.

  As described above, the auxiliary machine 14 is connected to the ECU 22 and is configured to operate according to a command from the ECU 22. Therefore, the control of the power consumption of the auxiliary machine 14 by the ECU 22 is performed by, for example, outputting a command for limiting the rotational speed of the auxiliary machine from the ECU 22 for auxiliary machines such as a hydrogen pump, a cooling water pump, and an air compressor. For example, for an auxiliary machine such as an air conditioner and a heater, the ECU 22 outputs a command for limiting or stopping the electric power of the auxiliary machine.

  FIG. 5 is a flowchart showing another example of the operation of the fuel cell system 1 according to the present embodiment.

  As shown in FIG. 5, first, in step S20, a signal of the electric power value that can be passed through the converter 16 is input to the ECU 22, and the ECU 22 compares the electric power that can be passed through the converter 16 and the maximum electric power consumed by the auxiliary machine 14. The

  When the passable power of the converter 16 is less than the maximum power consumed by the auxiliary machine 14, the ECU 22 limits the power consumed by the auxiliary machine 14 to be equal to or lower than the passable power passing through the converter 16 in step S22. . In step S24, the power required for the fuel cell 10 is output.

  In this way, by directly limiting the power consumed by the auxiliary machine 14, the amount of power supplied from the secondary battery 12 to the auxiliary machine 14 can be reduced, and the burden on the secondary battery 12 can be suppressed. Further, as the power consumption of the auxiliary machine 14 is reduced as described above, the power required for the fuel cell 10 is indirectly reduced, so that the power passing through the converter 16 is also reduced, and the converter 16 is further heated. Can be suppressed.

  On the other hand, if the power that can be passed through the converter 16 is equal to or greater than the maximum power consumed by the auxiliary machine 14, the power consumed by the auxiliary machine 14 is not limited, and the process proceeds to step S24 to request the power required for the fuel cell 10. Is output.

  As described above, in the fuel cell system of this embodiment, when the power that can be passed through the converter is less than the maximum power consumed by the auxiliary device, the auxiliary device is indirectly limited by limiting the power required for the fuel cell. By limiting the power consumed by the battery or directly limiting the power consumed by the auxiliary machine, the amount of power supplied from the secondary battery to the auxiliary machine can be reduced and the burden on the secondary battery can be suppressed.

  DESCRIPTION OF SYMBOLS 1 Fuel cell system, 10 Fuel cell, 12 Secondary battery, 14 Auxiliary machine, 16 Converter, 18 Load, 20 Inverter, 24, 26 Electric circuit.

Claims (3)

A fuel cell that generates electricity by an electrochemical reaction between an anode gas and a cathode gas;
A rechargeable secondary battery;
An auxiliary machine driven by electric power from the fuel cell or the secondary battery;
A voltage converter provided between the fuel cell and the auxiliary machine;
A fuel cell system comprising: limiting means for limiting power required for the fuel cell when the passable power passing through the voltage converter is less than the maximum power consumed by the auxiliary machine.   2. The fuel cell system according to claim 1, wherein the electric power required for the fuel cell by the control unit is a limit obtained by the passable power passing through the voltage converter / the maximum power consumed by the auxiliary device. The fuel cell system is limited to a value obtained by multiplying a rate by a power value required for the fuel cell. A fuel cell that generates electricity by an electrochemical reaction between an anode gas and a cathode gas;
A rechargeable secondary battery;
An auxiliary machine driven by electric power from the fuel cell or the secondary battery;
A voltage converter provided between the fuel cell and the auxiliary machine;
Control means for controlling the power consumed by the auxiliary machine to be equal to or lower than the passable power passing through the voltage converter when the passable power passing through the voltage converter is less than the maximum power consumed by the auxiliary machine; A fuel cell system comprising:

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