JPH05191978A - Power supply utilizing fuel cell - Google Patents

Abstract

PURPOSE:To prevent output power of fuel cell from increasing by decreasing the voltage or the frequency of AC output power from an inverter(IV) when the output current of the IV exceeds a set value thereby reducing the starting current of an external load, i.e., an AC motor. CONSTITUTION:DC power produced from fuel cells 1 is inverted through an inverter IV2 into AC power which is then fed to an external load unit 3. A control circuit 2f controls an IV element 2a based on information provided from a current detector 2e. The control circuit 2f gradually decreases the voltage or the frequency of AC output power from the IV2 at a predetermined rate as the output current increases until the output current to the external load unit 3 reaches a value set closely to the rated output current of the IV2. When the output current exceeds the set value, the IV element 2a is controlled to gradually decrease the voltage or the frequency of AC output power at a higher rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with an inverter for converting an output DC power of a fuel cell into an AC power and outputting the AC power to an external load device, and detecting information of a detection means for detecting the output power of the fuel cell. Based on the above, the present invention relates to a power supply device using a fuel cell, which is provided with control means for controlling the fuel supply amount to the fuel cell to increase as the output power value increases.

[0002]

2. Description of the Related Art In such a power supply device using a fuel cell, an amount of fuel commensurate with the output power is controlled by increasing the amount of fuel supplied to the fuel cell as the output power of the fuel cell increases. To generate DC power,
The output DC power from the fuel cell is converted into AC power by the inverter and output to the external load device. Conventionally, in such a power supply device using a fuel cell, an inverter converts the output DC power of the fuel cell into constant voltage and constant frequency AC power and outputs it to the external load device regardless of the output current value to the external load device. I was configured to do.

[0003]

By the way, when the external load device is an AC motor in particular, such an AC motor is
The rated current consumption value is extremely small when the number of revolutions is the rated number of revolutions (value determined by the power supply frequency), but when starting at the rated power supply voltage or power supply frequency, at startup (zero rotation speed)
A starting current several times as large as the rated consumption current value flows in the above, then the current decreases as the rotation speed increases, and when the rated rotation speed is reached, an extremely small current consumption value flows. On the other hand, it is known that the lower the power supply voltage or power supply frequency is, the smaller the starting current at the time of starting (zero rotation speed), that is, the smaller the difference from the rated current consumption value, is. However, conventionally, since the inverter is configured to output constant-voltage and constant-frequency alternating-current power, when the external load device is an alternating-current motor in particular, start the alternating-current motor at the rated power-supply frequency and voltage. Therefore, at the time of start-up, a very large start-up current flows rapidly, and the output power of the fuel cell rapidly increases. However, the increased supply of fuel commensurate with the rapid increase in the output power cannot be followed, so that the fuel cell is in a fuel shortage state, which causes deterioration of the fuel cell. Therefore, the conventional power supply device using the fuel cell has a problem of poor durability. The present invention has been made in view of the above circumstances, and an object thereof is to improve durability in a power supply device using such a fuel cell by rationally improving an inverter.

[0004]

A first characteristic structure of a power supply device using a fuel cell according to the present invention is that the inverter is
On the basis of the output current value to the external load device, when the output current value exceeds a set value, the voltage or frequency of the output AC power is reduced.

According to a second characteristic configuration, the output alternating current increases as the output current value increases until the output current value of the inverter reaches a set value based on the output current value to the external load device. When the voltage or frequency of electric power is gradually reduced at a predetermined reduction rate, and the output current value exceeds a set value,
It is configured such that the voltage or frequency of the output AC power is gradually reduced at a reduction rate higher than the reduction rate.

[0006]

According to the first characteristic configuration, when the output current value of the inverter increases and exceeds the set value, the voltage or frequency of the output AC power of the inverter is reduced. Therefore, when the external load device is an AC electric motor in particular, the starting current at the time of starting the AC electric motor can be reduced, and a sudden increase in the output power of the fuel cell can be avoided.

According to the second characteristic configuration, when the external load device is an AC motor in particular, the voltage or frequency of the output AC power of the inverter is set so that the output current value of the inverter is close to the rated output current value of the inverter. As the starting current of the AC motor gradually increases from the voltage or frequency corresponding to the value larger than the set value by a predetermined value at a large increase rate as the value decreases from the value larger by the predetermined value than the set value to the set value, the AC motor The rotation speed of can be quickly increased to near the rated rotation speed. Furthermore, as the output current of the inverter decreases from the time when it becomes less than or equal to the set value, the output current of the inverter is increased by gradually increasing the voltage or frequency of the output AC power to the rated voltage or rated frequency at a small increase rate. It is possible to gradually reduce from the set value to an extremely small rated current consumption value when the rotational speed of the AC motor reaches the rated rotational speed.

[0008]

According to the first characteristic structure, the output power of the fuel cell sharply increases and the increased supply of fuel commensurate with the increase cannot be followed, as in the above-described conventional case, so that the fuel cell can be used. The problem that the fuel cell deteriorates due to the lack of fuel can be reliably avoided, and the durability can be improved.

According to the second characteristic configuration, when the external load device is an AC motor in particular, the output power of the fuel cell rapidly increases even if the voltage or frequency of the output AC power is gradually increased from a low value to a rated value. It became possible to increase the rotation speed of the AC motor to the rated rotation speed as quickly as possible while avoiding the increase in the speed. Moreover, since it is possible to avoid the output current of the inverter from suddenly decreasing, it is possible to avoid the deterioration of the fuel cell due to the sudden decrease in the output power of the fuel cell and the excessive fuel supply amount. As a whole, the durability can be further improved.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

First, the structure of a power supply device using a fuel cell will be described with reference to FIG.

In this power supply device using a fuel cell, direct current power is generated by the fuel cell 1, and the output direct current power of the fuel cell 1 is converted into alternating current power by the inverter 2 and output to the external load device 3. Is configured. In the figure, 4 is a breaker interposed between the inverter 2 and the external load device 3.

The fuel cell 1 reforms a supplied fuel gas such as natural gas into a reformed gas containing hydrogen as a main component in the reforming section 1A and supplies the reformed gas to the power generation section 1B. In the power generation section 1B, the reformed gas is reformed. Hydrogen in the gas is reacted with oxygen in an oxygen-containing gas such as air supplied separately to generate and output DC power. Reference numeral 5 is a power detection device as a detection means for detecting the output DC power of the fuel cell, and reference numeral 6 is a fuel for the fuel cell 1 as the output DC power becomes larger based on the detection information of the power detection device 4. It is a control device as a control means for controlling the proportional valve 7 so as to increase the gas supply amount.

Next, a schematic structure of the inverter 2 will be described with reference to FIG.

Reference numeral 2a is an inverter element such as a thyristor or a GTO thyristor for converting DC power into AC power. The DC side is a capacitor 2b and the AC side is a coil 2c.
And a capacitor 2d are connected.

Reference numeral 2e denotes an inverter 2 to an external load device 3
2f is a current detector for detecting the output current value to the
It is a control circuit for controlling the inverter element 2a so as to adjust the voltage or frequency of the output AC power of the inverter 2 based on the detection information of the current detector 2e as described later.

That is, as shown in FIG. 2, the control circuit 2f sets the voltage or frequency of the output AC power of the inverter 2 so that the output current value to the external load device 3 is near the rated output current value of the inverter 2. Up to the set value (point A in the figure), as the output current value increases, the voltage or frequency of the output AC power is gradually reduced at a predetermined reduction rate, and the output current value reaches the set value (A in the figure). Point), the inverter element 2a is controlled so that the voltage or frequency of the output AC power is gradually reduced at a reduction rate higher than the reduction rate.

Therefore, when the external load device 3 is an AC electric motor, the set value is obtained by setting the voltage or frequency of the output AC power of the inverter 2 so that the output current value of the inverter 2 is close to the rated output current value of the inverter 2 (see FIG. The starting current of the AC motor 3 is higher than the set value (point A in the figure) as the set value (point A in the figure) decreases from a value (point B in the figure) larger by a predetermined value than the middle point A). Larger value than specified value (B in the figure)
Point) to the voltage or frequency (point C in the figure) corresponding to point D in the figure at a large increase rate, thereby increasing the rotational speed of the AC motor 3 to near the rated rotational speed. Can be raised. Further, as the output current of the inverter 2 decreases from the time when the output current becomes equal to or less than the set value (point A in the figure), the voltage or frequency of the output AC power increases at a small increase rate to the rated voltage or rated frequency (point E in the figure). ) To a small increase rate,
The output current of the inverter 2 is gradually changed from the set value (point A in the figure) to an extremely small rated current consumption value (point F in the figure) when the rotational speed of the AC motor 3 reaches the rated rotational speed. It can be reduced.

[Other Embodiments] Next, other embodiments will be listed.

In the above embodiment, the voltage or frequency of the output AC power of the inverter is set such that the output current value becomes larger as the output current value increases until the output current value to the external load device reaches the set value. Was gradually reduced at a predetermined reduction rate, and when the output current value exceeded a set value, the voltage or frequency of the output AC power was gradually reduced at a reduction rate higher than the reduction rate. The output AC power voltage or frequency is reduced when the output current value to the external load device exceeds the set value, or is gradually reduced with a large reduction rate as the output current value exceeds the set value and becomes large. You can

In the above embodiment, the case where the external load device is an AC motor has been illustrated, but the external load device is not limited to the AC motor.

In the above-mentioned embodiment, when the output current value of the inverter exceeds the set value, the control is performed so as to reduce the voltage or frequency of the output AC power.
Instead of this, when the rate of change of the output current value of the inverter exceeds a set value, control may be performed so as to reduce the voltage or frequency of the output AC power.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power supply device using a fuel cell.

FIG. 2 is a control example of voltage or frequency of output AC power of a power supply device using a fuel cell.

[Explanation of symbols]

 1 Fuel Cell 2 Inverter 3 External Load Device 5 Detection Means 6 Control Means

Claims (2)

[Claims] 1. An inverter (2) for converting the output DC power of the fuel cell (1) into AC power and outputting the AC power to an external load device (3), and detecting the output power of the fuel cell (1). Utilizing a fuel cell, which is provided with a control means (6) for controlling the fuel supply amount to the fuel cell (1) to increase as the output power value increases based on the detection information of the detection means (5) The inverter (2) reduces the voltage or frequency of the output AC power when the output current value exceeds a set value based on the output current value to the external load device (3). A power supply device using a fuel cell configured to perform. 2. The output of the inverter (2) increases as the output current value increases until the output current value reaches a set value based on the output current value to the external load device (3). When the voltage or frequency of the AC power is gradually reduced at a predetermined reduction rate, and when the output current value exceeds a set value, the voltage or frequency of the output AC power is gradually reduced at a reduction rate higher than the reduction rate. The fuel cell power supply device according to claim 1, which is configured.