JPH09171831A - Hybrid fuel cell system and is operating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive an external load from the beginning of starting of a fuel cell. SOLUTION: A relay switch RY1 is branched from a first feed path L11 between the relay switch RY1 and an external load within the first feed path L11 for supplying electricity from a DC-DC converter 2 connected to a fuel cell body 1 to the external load, and a relay switch RY2 is provided in an auxiliary feed path L21 connected to an open end voltage lower than the output voltage of the DC-DC converter 2. At the beginning of starting of the fuel cell body 1, the relay switch RY2 is turned on, and when the fuel cell body 1 is laid in steady operable state, the relay switch RY1 turned on as the relay switch RY2 is held in on-state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid fuel cell system and an operating method thereof, and more particularly to improvement of a power supply technique at the start of fuel cell startup.

[0002]

2. Description of the Related Art Conventionally, in a hybrid fuel cell system, when the fuel cell is started, hydrogen and air are supplied to the fuel cell main body, and electric power generation is started by their electrochemical reaction. Then, as the reaction progresses, the temperature inside the fuel cell body gradually rises and rises to the steady operating temperature, and the fuel cell body is in a steady operation state in which a predetermined voltage and current value can be obtained. For the first time, an external load was connected and was driving.

[0003]

However, since it takes a certain amount of time for the fuel cell main body to heat up to a predetermined operating temperature, in the conventional hybrid fuel cell system, it is necessary to immediately connect and drive an external load. There was a problem that I could not do it. The above-mentioned problems are particularly noticeable when the hybrid fuel cell system is used as an emergency power source that needs power immediately.

In view of the above problems, it is an object of the present invention to provide a hybrid fuel cell system capable of driving an external load from the start of starting and a method of operating the same.

[0005]

In order to achieve the above object, the hybrid fuel cell system according to claim 1 comprises:
A fuel cell main body and a first DC-DC converter for converting DC power from the fuel cell main body into a predetermined voltage and outputting the voltage.
A first DC-DC converter, a first power feeding path for feeding power from the first DC-DC converter to the first external load, and an auxiliary power feeding path branched from the first power feeding path. Convert
Storage battery having an open circuit voltage lower than the output voltage of the battery,
A first switch provided in the first power feeding path between the first DC-DC converter and a branch point to the auxiliary power feeding path, and a second switch provided in the auxiliary power feeding path. In a hybrid fuel cell system consisting of
The second switch is turned on at the start of the fuel cell main unit,
It is characterized in that the fuel cell body is equipped with a control means for turning on the first switch while keeping the second switch on when the fuel cell main body is in a steady operation possible state.

According to the configuration of the invention described in claim 1, when the fuel cell main body is started to be activated, the second power supply line provided in the auxiliary power feeding path is provided.
When the switch is turned on and the fuel cell main body is in the steady operation possible state, the first switch provided in the first power feeding path is turned on while keeping the second switch in the on state. The hybrid fuel cell system according to claim 2 is different from the hybrid fuel cell system according to claim 1 in that the hybrid fuel cell system is connected to the first power supply path between the first external load and the first switch, A current limiting type output for converting the DC power from the DC-DC converter or the storage battery of No. 1 into a predetermined voltage and outputting it, and drastically lowering the output voltage when the output current exceeds a predetermined set value. A second DC-DC converter having a built-in cutoff circuit;
Connected to the first power supply path between the first external load and the first switch, and a second power supply path for supplying power from the DC-DC converter to the second external load, A first DC-DC converter or a DC-AC inverter that converts DC power from the storage battery into AC power and outputs the AC power; and a DC-AC inverter that supplies power to a third external load. 3 and the second DC-DC converter
Connected to the second D in proportion to the increase of the load current.
It is characterized in that it is provided with a DC stabilizing circuit for slightly lowering the output voltage of the C-DC converter.

According to the configuration of the invention described in claim 2, the first
From the power feeding path, the second power feeding path, and the third power feeding path, when the fuel cell main body starts to operate, the power from the fuel cell main body after the fuel cell main body is in the steady operation state is available. When the output current is supplied and supplied to the external load from the second power supply path while the output current becomes equal to or higher than a predetermined set value, the output voltage sharply decreases, and the output voltage slightly decreases in proportion to the increase in the load current.

According to a third aspect of the present invention, there is provided a method for operating a hybrid fuel cell system, wherein a D connected to a fuel cell body is used.
A first switch is branched from the first power feeding path between the first switch and the external load in the first power feeding path for feeding power from the C-DC converter to the external load, and the DC-DC converter is provided. -In a hybrid fuel cell system in which a second switch is provided in an auxiliary power supply line connected to a storage battery having an open circuit voltage lower than the output voltage of the battery, the second switch is turned on at the start of starting the fuel cell body. And a step of turning on the first switch while keeping the second switch in the on state when the fuel cell main body is in a steady operation possible state.

According to the structure of the invention described in claim 3, when the fuel cell main body is started to be activated, the second power supply line provided in the auxiliary power feeding path is provided.
When the switch is turned on and the fuel cell main body is in the steady operation possible state, the first switch provided in the first power feeding path is turned on while keeping the second switch in the on state.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a hybrid fuel cell system according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a fuel cell main body for generating electricity by an electrochemical reaction between hydrogen gas supplied from a hydrogen cylinder (not shown) and air (oxygen) supplied by an air supply fan (not shown). And its output voltage is, for example, 12V. Reference numeral 2 is a first DC-DC converter that outputs the 12V electric power output from the fuel cell main body 1 at a stable voltage of 12V.
A first feed line L11 is provided between the DC-DC converter 2 and the first DC output terminal T1. In addition,
The first DC-DC converter has a drooping characteristic that drastically reduces the output voltage when the load current exceeds the maximum allowable current value, that is, the current value that deteriorates the fuel cell main body. Current limiting type output control circuit (not shown)
And a DC stabilizing circuit 21 similar to the DC stabilizing circuit 5 described later in detail. Here, the fuel cell FC is, for example, a portable fuel cell, and includes the fuel cell main body 1, the first DC-DC converter 2, the control device 13 described later, and the like. Reference numeral 3 is a storage battery having an open end voltage lower than the voltage output from the first DC-DC converter 2, and an auxiliary power feeding line L21 branched from a point C1 in the first power feeding line L11.
Connected to. 4 is the first DC-DC converter 2
Alternatively, it is a second DC-DC converter which boosts the DC power output from the storage battery 3 to 55V DC power and outputs the boosted DC power, wherein the point C2 in the first power supply path L11 and the second DC output terminal. The second power feeding path L12 that is connected to T2
It is provided inside. The second DC-DC converter 4 suddenly lowers the output voltage when the load current exceeds a current value that deteriorates the fuel cell body, that is, the maximum allowable current value. It incorporates a current limiting type output control circuit (not shown) having a drooping characteristic. A DC stabilizing circuit 5 as shown in FIG. 2 is connected to the second DC-DC converter 4. As shown in FIG. 2, the DC stabilizing circuit 5 includes an error amplifier 51 and a voltage Vz.
Of the reference voltage source 52, the resistance values of which are R1, R2,
R3 resistors R1, R2, R3, second DC-DC
It is composed of a sensor (for example, a hall element) 53 that generates a voltage proportional to the output current of the converter 4. The output voltage Eo is divided by the resistors R1, R2, R3 to obtain a voltage Eo. (R2 + R3) / (R1 + R2 +
R3) and the voltage generated by the sensor 53 and applied across the resistor R3 are applied to the inverting input terminal of the error amplifier 51 and the reference voltage Vz is applied to the non-inverting input terminal of the error amplifier 51. Positive and negative outputs corresponding to the difference are obtained, and the outputs are input to the second DC-DC converter 4. Reference numeral 6 denotes an inverter for converting the DC power output from the first DC-DC converter 2 or the storage battery 3 into AC power, which is a point C2 in the first power supply path L11 and an AC output terminal T3. And a third power supply line L connected between
It is provided in 13. In addition, the first power feeding path L1
1, a relay switch RY1 is provided between the first DC-DC converter 2 and the point C1, and a relay switch RY2 is provided in the auxiliary power feeding path L21. 7 is an ammeter for detecting the load current of an external load, 8 is a voltmeter for monitoring the voltage of the storage battery, 10 is a gas leak from the fuel cell FC or hydrogen cylinder and the pipes around them. Hydrogen gas sensors, which are connected to the control circuit 14, respectively. Reference numeral 9 denotes a temperature sensor for detecting the temperature of the fuel cell main body 1, which is connected to the control device 13. Reference numeral 11 is a start switch for starting the start of the fuel cell FC, and 12 is a main power switch for starting the entire system. Numeral 13 is a supply of hydrogen and air to the fuel cell main body, temperature monitoring of the fuel cell main body based on the detection result of the temperature sensor-9, monitoring of voltage value and current value of electric power output from the fuel cell, and fuel cell main body The control device controls the operation of the fuel cell FC such as stopping the operation of the fuel cell FC and transmitting an abnormal signal to the control circuit 14 when an abnormal temperature rise occurs. 14 is a relay switch RY1, R
It is a control circuit that controls power supply to an external load by turning on and off Y2, monitors the load current of the external load based on the detection result of the ammeter 7, and monitors the voltage of the storage battery 3 based on the detection result of the voltmeter 8. Further, the fuel cell FC has an LED (V-L) which is turned on when the voltage of the storage battery 3 becomes a predetermined value or less.
ED) and two LEDs (not shown), that is, an LED (I-LED) that is turned on when the load current exceeds a predetermined value, are attached and are respectively connected to the control circuit 14.

Regarding the operation of the control circuit 14 of the present hybrid fuel cell system configured as described above,
Description will be made based on the flowcharts shown in FIGS. FIG. 3 is a flowchart showing the operation control contents when the fuel cell of the present system is activated, and FIG. 4 is a flowchart showing the operation control contents when the fuel cell is in a steady operation.

First, with reference to FIG. 3, the contents of operation control at the time of starting the fuel cell of this system will be described. When the main power switch 12 is turned on in step S10, the process proceeds to step S11 to turn on the activation switch 11, and subsequently turn on the relay switch RY2 (step S12). Here, when the start switch 11 is turned on, the control of the control device 13 is started, and the fuel cell body 1
Supply of hydrogen and air to the fuel cell, monitoring of the temperature of the fuel cell body, monitoring of the generated voltage and current, etc. will begin. In addition, relay switch R
When Y2 is turned on, the storage battery 3 and the first DC output terminal T
1, second DC output terminal T2 and AC power output terminal T
3 are electrically connected to each other, and the auxiliary power supply line L21 to the first power supply line L11 or the auxiliary power supply line L21 to the first power supply line L1.
1 part (between C1 and C2) to the second power supply line L12 or the auxiliary power supply line L21 to a part of the first power supply line L11 (C1
~ Between C2) ~ Supply of electric power from the storage battery 3 to the external load is started via the third power feeding path L13.

When the processing up to step S12 is completed,
In step S13, it is determined whether the fuel cell is in a steady operation possible state. The determination as to whether or not a steady operation is possible is made by a signal output from the control device 13. As described above, the control device 13 monitors the voltage value and current value of the electric power output from the fuel cell,
When both the voltage value and the current value exceed the values set in advance in the control program, the steady operation enable signal is output to the control circuit instead of the steady operation disable signal that has been output until then. Here, when the control device 13 outputs the steady operation disable signal and it is determined that the steady operation is not possible,
The process proceeds to step S20 to determine whether or not the voltage of the storage battery 3 is equal to or higher than a value Vm defined in advance in the control program. If not, the process proceeds to step S21 to turn on the V-LED, while, In the above case, the process proceeds to step S22, the V-LED is turned off, and then the process proceeds to step S23. In step S23, it is determined whether or not the load current of the external load is greater than or equal to a value Im preset in the control program. If not, the process proceeds to step S24 to turn off the I-LED, while
In the above case, the process proceeds to step S25, the I-LED is turned on, and then the process proceeds to step S26. In step S26, from the detection result of the hydrogen gas sensor-10,
When it is determined that there is a gas leak in the fuel cell FC or the like, and when it is determined that there is a gas leak, the process proceeds to step S27, the relay switch RY2 is turned off, and then the controller 1
An operation stop command is output to step 3 (step S28), and the process ends. Here, the power supply to the external load is stopped by turning off the relay switch RY2, and the control device 13 that has received the operation stop command takes measures to stop the supply of hydrogen and oxygen to the fuel cell body 1, The start switch 11 is turned off. On the other hand, if it is determined in step S26 that there is no gas leakage, the process returns to step S13.

If it is determined in step S13 that the steady operation is possible by the signal from the control device 13, the process proceeds to step S14 to turn on the relay switch RY1. When the relay switch RY1 is turned on, the fuel cell body 1, the AC power output terminal T2 and the DC power output terminal T
1 is electrically connected to the first power feeding path L11 or part of the first power feeding path L11 to the second power feeding path or part of the first power feeding path L11 to the third power feeding path. Supply of electric power from the fuel cell main body 1 to the external load is started, and surplus electric power not supplied to the external load is transferred via the auxiliary power feeding path L21.
It is used to charge the storage battery 3.

When step S14 is completed, the process is performed as shown in FIG.
Go to step S30 shown in. Hereinafter, the content of the operation control during the steady operation of the fuel cell will be described with reference to FIG. In step S30, it is determined whether or not the load current of the external load is equal to or more than the above current value Im. If it is, the process proceeds to step S31, and the I-LED is turned on. The process proceeds to step S32, the I-LED is turned off, and then the process is step S33.
Proceed to.

In step S33, the above step S26
When it is determined that there is no gas leakage, the process proceeds to step S34. In step S34, it is determined whether the main power supply switch 12 is turned off. If it is determined that the main power supply switch 12 is not turned off, the process returns to step S30. On the other hand, if it is determined in step S33 that there is a gas leak or if it is determined in step S34 that the main power supply has been turned off, the process proceeds to step S35, where the relay switch RY1 is turned off, and then RY2 is turned off (step Then, a fuel cell operation stop command is output to the control device 13 (step S37), and the process ends. Where the relay
By turning off the switches RY1 and RY2, the supply of electric power to the external load is stopped, and the control device 13 that has received the operation stop command takes measures to stop the supply of hydrogen and oxygen to the fuel cell body 1, The start switch 11 is turned off.

Next, a case where two hybrid fuel cell systems are used and an external load is connected to the second DC power output terminal T2 of both systems for parallel operation will be described. The operation of the circuit composed of the second DC-DC converter 4 and the DC stabilizing circuit 5 will be described with reference to FIG. The sensor-53 generates a voltage proportional to the load current Io, and the generated voltage is applied across the resistor R3. At this time, when the load current Io is small, the voltage generated in the sensor-53 is also small, and therefore the voltage input to the inverting input terminal is not affected so much. DC converter 4
Is mainly divided voltage of output voltage Eo Eo (R2 + R3)
A signal determined by / (R1 + R2 + R3) is output, and as a result, the output voltage is maintained at about Eo. on the other hand,
As the load current Io increases, the voltage applied across the resistor R3 also increases. Therefore, the voltage input to the inverting input terminal increases, which is the same as the output voltage Eo increasing. The error amplifier 51 outputs to the second DC-DC converter 4 a signal that lowers its output voltage. As a result, the second DC
The output voltage of the DC converter 4 has a characteristic that it decreases as the load current increases.

Next, two hybrid fuel cell systems (system I and system II) are used, and an external load is applied to each second DC output terminal to which power is supplied via the circuit as described above. The operation in the case of connection and parallel operation will be described with reference to FIG. FIG. 5 is a diagram showing output voltage / current characteristics and current sharing characteristics of each of system I and system II when external loads are operated in parallel. In the figure, Ia is the characteristic of the system I, and the output voltage tends to decrease as the output current Io1 increases from 0 (that is, from the left side to the right side of the figure). IIa is the characteristic of the system II, and the output current Io
The output voltage tends to decrease as 2 increases from 0 (ie, from the right side of the figure to the left side). Here, the system I is the current Io1 and the system II is the current Io.
The total current of Io, which is the sum of both, is the output current to the external load.

Here, when the output voltage of one system decreases, the amount of current supplied from the other system increases, but when a large amount of current flows, it acts so as to decrease the output voltage. When the voltages are balanced, the share of both load currents is determined. Therefore, as shown in FIG. 5, even if one output voltage fluctuates by ΔE during parallel operation, the output current of each system can be made to change only slightly as indicated by arrow Y. The load sharing between the two can be held substantially evenly. Even when an external load is connected to the first DC output terminal and parallel operation is performed, the same effect as when the external load is connected to the second DC output terminal described above and parallel operation is obtained is obtained. It goes without saying that it will be done.

In the first DC-DC converter and the second DC-DC converter, the load current exceeds the maximum allowable current value, that is, the current value at which the load cell deteriorates. Since the current limiting type output control circuit having the drooping characteristic that sharply decreases the output voltage when it is turned on is built in, deterioration of the fuel cell due to overload can be prevented.

[0021]

As described above, according to the hybrid fuel cell system of the first aspect of the present invention, the second switch provided in the auxiliary power supply path is turned on when the fuel cell main body starts to operate, and the fuel cell main body is When the steady operation becomes possible, the first switch provided in the first power feeding path is turned on while keeping the second switch in the on state, so that the storage battery connected to the auxiliary power feeding path at the same time as the start of startup. From this point, the power can be supplied to the external load, and after the steady operation is possible, the storage battery can be charged for the next use.

According to the hybrid fuel cell system of the second aspect of the invention, in addition to the effect of the hybrid fuel cell system of the first aspect, the first power feeding path, the second power feeding path, and the third power feeding path are provided. At the start of the fuel cell main body starting from the power supply path of No. 2, after the fuel cell main body is in the steady operation state from the storage battery, the electric power is supplied from the fuel cell main body to the external load from the second power supply path. If the output current exceeds the specified value during power feeding, the output voltage will be drastically reduced, and the output voltage will be slightly reduced in proportion to the increase of the load current. In addition, there is an abundance of types, and when power is supplied from the second power supply path, it is possible to protect the fuel cell main body due to overload. Also,
When multiple external loads are operated in parallel from the second power supply path using this system, the load sharing is stable for each system, and the capacity of the power supplied to the external loads is increased. It becomes possible.

Further, according to the method of operating the hybrid fuel cell system according to the invention of claim 3, the second switch provided in the auxiliary power supply path is turned on at the start of starting the fuel cell main body, and the fuel cell main body is turned on. When the normal operation is possible, the first switch provided in the first power feeding path is turned on while the second switch is kept in the ON state, so that the auxiliary power feeding path is connected at the same time as the start of activation. After the power is supplied from the storage battery to the external load, and after the steady operation is possible, the storage battery can be charged in preparation for the next use.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a hybrid fuel cell system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a DC stabilizing circuit 5 in the above embodiment.

FIG. 3 is a flowchart showing a processing procedure of a control circuit in the above embodiment.

FIG. 4 is a flowchart showing a processing procedure of a control circuit in the above embodiment.

FIG. 5 is a second DC-D in each system when an external load is operated in parallel from a second DC output terminal by using the two hybrid fuel cell systems according to the above embodiment.
It is a figure which shows the output voltage / electric current characteristic of C converter, and a current sharing characteristic.

[Explanation of symbols]

 1 Fuel Cell Main Body 2 First DC-DC Converter 3 Storage Battery 4 Second DC-DC Converter 5 DC Stabilization Circuit 6 DC-AC Inverter L11 First Power Supply Line L12 Second Power Supply Line L13 Third feeding line L21 Auxiliary feeding line RY1 relay switch RY2 relay switch

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shingo Washimi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Masaki Ishizawa 3-19 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 In Nippon Telegraph and Telephone Corporation (72) Inventor Yutaka Takita 3-19-3 Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Inside Nippon Telegraph and Telephone Corporation (72) Inventor Tsutomu Ogata 3-19 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. 2 within Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A fuel cell main body, a first DC-DC converter for converting DC power from the fuel cell main body into a predetermined voltage and outputting the predetermined voltage, and a first DC-DC converter to a first DC-DC converter. 1 is connected to a first power feeding path for feeding an external load and an auxiliary power feeding path branched from the first power feeding path, and has an open end voltage lower than the output voltage of the first DC-DC converter. A storage battery, a first switch provided between the first DC-DC converter and a branch point to the auxiliary power feeding path in the first power feeding path, and provided in the auxiliary power feeding path In the hybrid fuel cell system including the second switch, the second switch is turned on at the start of starting the fuel cell body,
A hybrid fuel cell system comprising: a control means for turning on the first switch while keeping the second switch in the on state when the fuel cell main body is in a steady operation possible state. 2. The first power feeding path is connected between the first external load and the first switch, and the first D
C-DC converter or DC power from the storage battery is converted into a predetermined voltage and output. When the output current exceeds a predetermined set value, the output voltage is drastically dropped. Second DC-D with built-in circuit
A C converter, a second power feeding path for feeding power from the second DC-DC converter to a second external load, the first external load and the first switch between the first external load and the second switch. A DC-AC inverter connected to the first power feeding path and converting DC power from the first DC-DC converter or the storage battery into AC power and outputting the AC power; and from the DC-AC inverter. A third feed line for feeding a third external load and the second DC-DC converter are connected, and the output voltage of the second DC-DC converter is proportional to the increase of the load current. 2. The hybrid fuel cell system according to claim 1, further comprising a DC stabilizing circuit that slightly reduces 3. A first power supply path for supplying power to an external load from a DC-DC converter connected to the fuel cell body.
Switch between the first switch and the external load
In the hybrid fuel cell system, the second switch is provided in the auxiliary power supply path that is branched from the power supply path and is connected to the storage battery having an open circuit voltage lower than the output voltage of the DC-DC converter. A step of turning on the second switch at the start of activation of the main body; a step of turning on the first switch while holding the second switch in the on state when the fuel cell main body is in a steady operation possible state; A method for operating a hybrid fuel cell system, comprising: