JPH0475420A - Dc parallel operating system for fuel cell - Google Patents

Abstract

PURPOSE:To facilitate load sharing operation between a fuel cell power supply and a rectifier by connecting the output from the fuel cell power supply and the output from the rectifier for rectifying AC power of a commercial power supply or other power generating source in parallel and feeding a load with power. CONSTITUTION:Outputs from a fuel cell power supply 30 and a rectifier 5 are connected in parallel, output capacity of the fuel cell power supply 30 is set lower than or equal to the minimum current consumption or voltage of a vari able load or between a peak value and the minimum value so that the load current or power is fed entirely from the fuel cell power supply 30 when the load current or power is lower than or equal to the rated output current or power of the fuel cell power supply 30 whereas at least a rated output current or power is fed from the fuel cell power supply 30 when the load current or power exceeds the rated output current or power of the fuel cell power supply. In addition, digital control technology is employed in the sharing control of load 100.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel cell energy system that converts the DC output of a fuel cell or other source into a voltage using a DC power supply device and supplies power to a load, and in particular, This invention relates to a fuel cell direct current parallel operation system that aims to reduce the cost of creating a fuel cell energy system by sharing the load with the output of a rectifier that uses a power source or an engine generator as input.

[Prior Art] Since a fuel cell generates DC power through an electrochemical reaction between hydrogen and oxygen, it is also possible to directly supply power to a DC load. However, it is generally necessary to convert the voltage of the fuel cell output in many cases, and in that case, the voltage is converted using a DC power supply device that inputs the DC output of a fuel cell or other device to supply power to the load. In a fuel cell power source consisting of such a fuel cell and a DC power supply device that receives the output of the fuel cell and other sources as input, when the power consumption of the load changes over time, the output changes according to the peak value of the load power consumption. If the capacity is determined, the fuel cell power source will have to operate at partial load for a long time with a considerable amount of surplus output remaining, and the cost of creating the fuel cell power source will be high compared to the actual amount of output power. There is a problem.

Therefore, instead of adjusting the 8-power capacity of the fuel cell power supply to the peak value of the power consumption of the fluctuating load, for example, the 8-power capacity of the fuel cell power source is selected to be below the minimum power consumption value or to a value between the peak value and the minimum value. Select a fuel cell power source that matches the average power consumption, and always operate the fuel cell power source at approximately the rated output, and for parts that exceed the output of the fuel cell power source, use a separate DC output power source, such as a commercial power source. Alternatively, it is possible to reduce the cost of creating a fuel cell energy system by supplying power from the output of a rectifier that uses the engine generator as input, and the applicant has proposed
No. 7771) proposed a fuel cell direct current parallel operation system shown in FIGS. 7 and 8.

To explain this conventional example from FIG. 7, the present system includes a fuel cell 1, a DC power supply device 2 which takes the output of the fuel cell as an input, and has a DC power supply main circuit 2-1 and an output voltage constant voltage control circuit 2-2. A fuel cell power source 3 consisting of a fuel cell power source 3 and a rectifier 5 for rectifying a commercial power source 4 are provided, and their outputs are connected in parallel to supply power to a load 100. In this conventional example, in order to perform load sharing control between the DC power supply device 2 and the rectifier 5, a load current/power detection means 6 is installed in the fuel cell DC parallel operation system to output a signal IL corresponding to the load current or power. It is detected and sent to the DC power supply output current/power setting means 8. In response to this, the DC power supply output current/power setting means 8 outputs a signal ■, and the fuel cell power supply 3
The value corresponding to the rated current or power of I LMAX
If IL is larger than I LNAX, then I
If LMAX is smaller than IL or I LKA8, it is
is sent to the DC power supply device output voltage control signal output means 9. The DC power supply device output voltage control signal output means 9 includes:
A signal 1 corresponding to the output current or power of the DC power supply device 2 sent from the DC power supply device output current/power detection means 7. and the signal IL or ILMAX sent from the DC power supply output current/power setting means 8,
The output voltage constant voltage control circuit 2 outputs a signal vQ according to the error.
-2 to change the output voltage of the DC power supply main circuit 21.

Next, FIG. 8 will be explained. FIG. 8 shows an example of the output voltage constant voltage control circuit 2-2 for changing the output voltage of the DC power supply 2 by the output signal 9 of the signal output means 9 for controlling the output voltage of the DC power supply of the conventional example. It shows.

This output voltage constant voltage control circuit 2-2 includes an operational amplifier 11
A reference voltage composed of a resistor 14 and a Zener diode 15 forming an output voltage setting section is inputted to one input (on the resistor 12 side) of an error amplifier composed of resistors 12 and 13 via a backflow blocking diode 16, and the other The output voltage of the DC power supply 2 can be adjusted by inputting the output voltage of the DC power supply 2 after being divided by the resistors 17 and 18, and sending the output of the error amplifier to the drive control circuit 10 including the pulse width modulation circuit. We are trying to stabilize the situation. Further, by connecting the output signal vQ of the signal output means 9 for controlling the output voltage of the DC power supply device to the output voltage setting section at the connection point between the diode 16 and the resistor 12 via the reverse current blocking diode 19, the output signal vQ can be used to control the DC current. The configuration is such that the output voltage of the power supply device 2 is changed. Therefore, by increasing the level of the output signal VQ, the output voltage of the DC power supply main circuit 2-2 can be increased, and thereby the load current of the DC power supply 2 or the ratio of power sharing can be increased. .

Further, a DC power supply output current/power detection means 7, a signal output means for controlling the output voltage of the DC power supply 9, and an output voltage constant voltage control circuit 2-2. Since a feedback loop consisting of the DC power supply main circuit 2-1 is configured, the signal I6 corresponding to the output current or power of the DC power supply 2 sent from the DC power supply output current/power detection means 7 is
can be made equal to the signal 1 or ILMAX sent from the DC power supply output current/power setting means 8. That is, the output current or power of the DC power supply device 2 can be adjusted to the current or power corresponding to the value set by the DC power supply device output current/power setting means 8.

Since it is configured and operates as described above, if the load current or power is less than the rated output current or power of the fuel cell power source 3, all the load current or power is supplied from the fuel cell power source 3, and the load current or power is If exceeds the rated output current or power of the fuel cell power source 3, the fuel cell power source 3 can supply power at least with the rated output current or power.

[Problems to be Solved by the Invention] However, the conventional fuel cell DC parallel operation system described above does not have a configuration that allows an operator or maintainer to easily control the load sharing between the fuel cell power source 3 and the rectifier 5. It was difficult to say that the situation had been fully developed. For example, when installing a system, it is necessary to perform an operation test on each of the fuel cell power supply 3 and rectifier 5 up to the rated output, but since the capacity of the test load is generally not sufficient, Depending on the capacity, it may be necessary to individually stop the fuel cell power supply 3 and the rectifier 5, or to disconnect the power supply lines for each output individually, which poses the problem of not being able to perform tests efficiently and quickly. Atsu tko. After the introduction of the fuel cell DC parallel operation system, when the power consumption of the load I00 is always maintained within the rating of the fuel cell power supply 3 to ensure that it does not fall below the initial prediction (in this case, the power consumption of the load I00 is always maintained within the rating of the fuel cell power supply 3). The willpower of discovery,
It is necessary to check the normality of the commercial power supply system including the rectifier 5 in the power supply state as appropriate, but at this time, there is a load sharing control method that can easily transfer the load sharing to the rectifier 5 side. There is a problem that there is no X.As mentioned above, in the conventional fuel cell DC parallel operation system aimed at reducing the cost of creating a fuel cell energy system, load sharing can be achieved with simple operations. The problem was that it was necessary to clarify the control method that could be used.

The present invention was devised to solve the above-mentioned problems, and an object of the present invention is to provide a fuel cell DC parallel operation system in which load sharing between a fuel cell power source and a rectifier can be easily controlled.

[Means for Solving the Problems] The structure of the fuel cell DC parallel operation system of the present invention for achieving the above object is as follows: A fuel cell and a DC power supply device that receives the output of the fuel cell and other sources as input. A fuel cell direct current parallel system that has a fuel cell power source, and connects the output of this fuel cell power source in parallel with the output of a rectifier that rectifies AC power output from a commercial power source or other power generation source to supply power to a load. In the operation system, the DC III source device is configured with a switching power supply device having a constant output voltage control circuit, and the fuel cell DC parallel operation system detects the current or power supplied to the load and generates a digital signal corresponding to the current or power. The current that outputs /
1i power signal generation means; a fuel cell power supply output current/power signal generation means for detecting the current or power supplied to a load by the fuel cell power supply and outputting a digital signal corresponding thereto; Digital signal comparison means for comparing a digital signal output from the power signal generation means and a digital signal output from the current/power signal generation means and outputting a digital signal according to the difference; and the digital signal comparison means. D/A conversion means for converting a digital signal output from the D/A conversion means into an analog signal, and an output voltage setting provided in the output voltage constant voltage control circuit of the switching power supply device, the analog signal output from the D/A conversion means being and controlling the output voltage of the switching power supply in accordance with fluctuations in the current or power supplied to the load by the fuel cell DC parallel operation system or fluctuations in the output voltage of the rectifier. The present invention is characterized in that it is configured to control the load sharing ratio of the output of the fuel cell power source.

[Function] The present invention is capable of connecting the output of a fuel cell power source, which is composed of a fuel cell and a switching power supply device that takes the output of the fuel cell and other sources as input, and has an output voltage constant voltage control circuit, and an alternating current from a commercial power source or other power generation source. We decided to share the load with the output of the rectifier that rectifies the output by changing the output voltage of the switching power supply using the output voltage constant voltage control circuit, and we also applied digital signal processing technology to control the output voltage constant voltage control circuit. By incorporating this, it becomes easier to realize load sharing, and the operation of setting the load sharing ratio becomes easier, allowing testing and maintenance to be carried out quickly and easily.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram illustrating a first embodiment of the present invention, showing a method for controlling the output voltage of the fuel cell power source (which may also be referred to as the output voltage of the switching power supply). It is a block diagram of a parallel operation system. In this embodiment, the same reference numerals as in the conventional example shown in FIG. 7 have the same functions. This example uses a fuel cell (FC)
1, and a switching power supply 21 having a switching power supply main circuit 21-1 and an output voltage constant voltage control circuit 21-2 whose outputs are input, and a commercial power supply +1 (CS) 4. A configuration is provided in which a rectifier 5 for rectification is provided, and the respective outputs are connected in parallel to supply power to a load 100. Here, in this embodiment, in order to share the load between the fuel cell power supply 30 and the rectifier 5, that is, the load between the switching power supply 21 and the rectifier 5, an A/
A current/power signal generation means 60 having a D conversion means and connected to the power supply line to the load 100 and detecting load current or power and outputting a digital signal corresponding thereto;
A fuel cell power supply output current/power signal generating means that connects the conversion means to the output line of the fuel cell power supply, detects the current or power supplied by the fuel cell power supply 30 to the load 100, and outputs a digital signal corresponding to the current or power. 70, a digital signal that compares the digital signal output from the current/power signal generation means 60 and the digital signal output from the fuel cell power supply output current/power signal generation means 70, and outputs a digital signal according to the difference. It is equipped with a signal comparison means 91 and a D/A conversion means 92 for converting the digital signal outputted from the digital signal comparison means 9■ into an analog signal, and the analog signal output from the D/A conversion means 92 is connected to the switching power supply. Device output voltage constant voltage control circuit 2
Connect to the output voltage setting section provided in 1-2. In the above, the output voltage constant voltage control circuit 21-2 can be configured in the same manner as the conventional example shown in FIG. 8, so in this embodiment, the same circuit configuration as that shown in FIG. 8 is used.

The operation and effect of the first embodiment configured as above will be described below.

This embodiment basically connects the output of the fuel cell power supply 30 and the output of the rectifier 5 in parallel, and supplies the output current or power to the load exceeding the rating of the fuel cell power supply 30 to the commercial power supply 4.
The burden is shared between the two parties. Here, the load sharing ratio between the output current on the fuel cell power supply 30 side and the output current on the rectifier 5 side (commercial power supply 4 side) is determined by dividing the output voltage of the switching power supply main circuit 21-1 into the output voltage constant voltage control circuit 21. -2
It is controlled by changing the . Moreover, a feature is that the output voltage constant voltage control circuit 21-2 is controlled using digital control technology. That is, its operation will be described as follows.

First, the current/power signal generation means 6o detects the load current or power, A/D converts this analog signal into a digital signal, and sends the digital signal corresponding to the load current or power to the digital signal comparison means 91. do. The fuel cell power supply output current/power signal generation means 70 detects the output current or power of the fuel cell power supply, converts it into a digital signal, and then sends this digital signal to the digital signal comparison means 91. The digital signal comparison means 91 compares the digital signal outputted from the current/power signal generation means 60 and the digital signal outputted from the fuel cell power source output current/power signal generation means 7°, and calculates the difference. D the digital signal according to
/A conversion means 92. For example, when the digital signal output from the fuel cell power supply output current/power signal generation means 70 is smaller than the digital signal output from the current/power signal generation means 60, the digital signal output from the digital signal comparison means 91 is The D/A conversion means 92 increases by 1 unit, and conversely decreases by 1 unit when it is larger.
Send to. The D/A conversion means 92 converts the digital signal output from the digital signal comparison means 91 into an analog signal, and converts this analog signal into an output voltage setting section provided in the output voltage constant voltage control circuit 21-2 of the switching power supply device. Add to.

Next, in the operation of the output voltage control circuit 21-2, referring to FIG. 14. A reference voltage formed by a Zener diode 15 is inputted via a reverse current blocking diode 16, and the output voltage of the switching power supply main circuit 21-1 is inputted after being divided by a resistor 17.18 to the other input, and the error amplifier is inputted to the other input. Drive control circuit 1 whose output includes a pulse width modulation circuit
0, the switching power supply device 21
The output voltage can be stabilized. Further, the output of the D/A converting means 92 is connected to the output voltage setting section of the output voltage constant voltage control circuit 21-2 via the reverse current blocking diode 19, so that the output voltage is sent from the D/A converting means 92. It is possible to change the eight voltages of the main circuit 21-1 of the switching power supply device using an analog signal, and by raising and lowering the level of this analog signal, the output voltage of the switching power supply device 21 is increased or decreased, and thereby the switching power supply device It is possible to increase or decrease the proportion of load current or power shared by 21.

Furthermore, fuel cell power supply output current/power signal generation means 70
．． Digital signal comparison means 91. D/A conversion means 92.
Since a feedback loop consisting of the output voltage constant voltage control circuit 21-2 and the switching power supply unit bundle circuit 21-1 is configured, the fuel cell power supply 30, that is, the switching power supply output from the fuel cell power supply output current/power signal generation means 70, Output voltage control is performed to bring the digital signal corresponding to the output current or power of the power supply device 21 closer to the digital signal sent out from the current/'I4 force signal generating means 60. That is, output voltage control is performed to match the output current or power of the fuel Si power source 30 to the load current or power.

In addition, in order to deal with the case where the load current or power exceeds the current or power that fuel cell #30 can supply,
A limit is set on the digital signal from the current/power signal generation means 60 (load sharing setting means 80 shown in FIG. 4, which will be described later, can be used for this purpose), and the output current is rated as the output voltage characteristic of the switching power supply device 21. If the output voltage exceeds this value, the output voltage decreases as the load resistance decreases. By clamping the signal output with a Zener diode, the load current or power exceeding the load current or power shared by the fuel cell power source 30 can be shared by the rectifier 5.

Furthermore, in the above explanation, it may seem as if the fuel cell power supply 30 controls the output voltage of the switching power supply 21 to change only when the load current changes in order to perform a predetermined load sharing, but if Even if the load current is constant, the output voltage of the rectifier 5 increases due to voltage fluctuations in the commercial power source 4, and the output current of the rectifier 5 attempts to increase. In order to do this, the output voltage of the switching F4 source device 21 is of course controlled to be increased.

Since this embodiment is configured and operates in this manner, the output capacity of the fuel cell power source 30 is selected to be less than or equal to the minimum value of the current consumption or voltage of the fluctuating load, or a value between the peak value and the minimum value. , if the load current or power is less than the rated output current or power of the fuel cell power supply 30,
If all load current or power is supplied from the fuel cell power supply 30 and the load current or power exceeds the rated output current or power of the fuel cell power supply 30, the fuel cell power supply 30
From zero, at least the rated output current or power can be supplied. Therefore, it is possible to make a fuel cell, which is expensive to start up, to a scale that allows it to operate at or near its rated operation, and to make effective use of it.

In addition to the above, since this embodiment uses digital control technology to control the load sharing of the output current to the load 100, various setting values and conditions can be easily changed, so load sharing can be easily and quickly performed. It is possible to change the ratio of , shift the load sharing to the commercial power supply 4 side, and provide a load sharing control method that is easy to test.

Further, in the above description, the case where the current or power that is the detection target of the current/power signal generation means 60 and the fuel cell power supply output current/power signal generation means 70 is the same detection target is explained, but the current/l power is not necessarily detected. Signal generating means 60
It is not necessary to match the detection targets of the fuel cell power supply output current/power generation means 70 and the fuel cell power supply output current/power generation means 70. For example, the current/power signal generation means 60 detects analog power and outputs a corresponding digital signal, and the tintal signal comparison means 91
in some way (for example, Sui.

The output voltage of the chingumi source device 21 is detected by a means not shown in FIG. 1, and the statistic signal from the current/power signal generation means 60 is divided by a digital signal corresponding to this output voltage. This is because if the current is converted into a digital signal, there is no problem even if the current is detected by the fuel cell power source output current/power signal generating means 70, 71.

Note that a personal computer is used as the digital signal comparison means 91,
An A/D conversion board is connected to the current/power signal generation means 60 and the fuel cell power supply output current/power signal generation means 70.
It goes without saying that if a D/A converter is used as the A converting means 92, the above-mentioned digital control can be realized, and the advantages of the above-mentioned digital control can be further brought out.

Furthermore, if the regulation of the switching power supply 21 is too good, the change in the output voltage with respect to the change in the output current of the switching power supply 21 becomes small, so when the rectification of the rectifier 5 is also good, load sharing control is performed. In that case, considering the minimum unit of change in the output of the D/A conversion means 92, the switching power supply device 21 should be given a characteristic in which the output voltage depends on the output current. Needless to say, it is necessary.

Furthermore, it goes without saying that the dependence of the output voltage on the output current may be provided in the rectifier 5, or may be provided in both the switching power supply device 21 and the rectifier 5.

FIG. 2 is a block diagram illustrating a second embodiment of the present invention, in which the same symbols as those in the first embodiment of FIG. 1 have the same functions. The second embodiment shown in FIG. 2 is the same as the first embodiment shown in FIG.
The difference from the above embodiment is that the detection means for the current or power supplied to the load 100 by the fuel cell DC parallel operation system is connected to the output current or power of the fuel cell power source 30 and the rectifier 5.
The point is that the output current or power of each is detected individually, and these are added to form a current/power signal generating means. That is, 6
1 is a means for detecting the output current or power of the rectifier 5 and outputting a corresponding digital signal through A/D conversion; 62 is a means for outputting the digital signal and the output current/power signal generating means 70 from the fuel cell power source output current/power signal generating means 70; This is an adder that adds the digital signals of the load current or the power consumption of the load and sends the result to the digital signal comparison means 91 described above as a digital signal that detects the load current or the power consumption of the load. Even with this configuration, the same operation as the first embodiment shown in FIG. 1 described above is performed.
It is clear that it works similarly.

Alternatively, it is of course possible to perform processing using an analog signal until addition in the adder 62 described above, and to perform A/D conversion at the output of the adder 62. In short, any current/power signal generation means that the fuel cell direct current parallel operation system can detect the current or power supplied to the load and output a digital signal corresponding thereto may be used. However, when a personal computer is used as the digital signal comparison means 91, the configuration is simpler if the personal computer also has the function of the adder 62.

FIG. 3 is a block diagram illustrating a third embodiment of the present invention, and the same symbols as those in the first embodiment of FIG. 1 have the same functions. The third embodiment shown in FIG. 3 or the first embodiment shown in FIG.
The difference from the embodiment is that the fuel cell power source 30 or the load 100
The fuel cell DC parallel operation system detects the current or power supplied to the load 100 by the fuel cell DC parallel operation system and the current or power supplied to the load 100 by the rectifier 5. Rectifier 5 or load 100 from the current or power supplied to the load
The current or power supplied to the fuel cell power source is subtracted from the current or power supplied to the fuel cell power source to generate an output current/power signal. That is, 61
is a means for detecting the current or power supplied to the load by the rectifier 5 and outputting a corresponding digital signal,
74 subtracts a digital signal corresponding to the current or power supplied to the load by the rectifier 5 from the digital signal from the current/power signal generation means 60 to generate the digital signal corresponding to the current or power supplied to the load by the fuel cell power source. This is a subtracter that sends the signal to the digital comparison means 91 of. It is clear that even with this configuration, the same operation and effect as in the first embodiment shown in FIG. 1 described above is performed. Further, the subtracter 74 described above processes analog signals until subtraction, and outputs the A/D signal from the subtracter 74.
May be converted. In short, any fuel cell power source output current/power signal generating means may be used as long as it is capable of outputting a digital signal corresponding to the current or power supplied to the fuel cell power source or load. However, when a personal computer is used as the digital signal comparing means 91 as in the second embodiment, the configuration is simpler if the personal computer also has the function of the subtracter 74.

FIG. 4 is a block diagram illustrating a fourth embodiment of the present invention, and the same symbols as those in the first embodiment of FIG. 1 have the same functions. The fourth embodiment in FIG. 4 is the same as the first embodiment in FIG.
The difference from the above embodiment is that the digital signal comparison means 9
Load sharing setting means 80 converts the digital signal from the current/power signal generating means 60 into a digital signal for the fuel cell power source 30 to share the load current or power at a predetermined ratio. The point lies in the intervention.

The operation and effects of the fourth embodiment configured as described above will be described below.

The current/power signal generation means BO of this embodiment detects the load current or power, A/D converts this analog signal into a digital signal, and sends the digital signal corresponding to the load current or power to the load sharing setting means 80. Send. The load sharing setting means 80 receives the digital signal from the current/power signal generating means 6o, and converts this digital signal into a digital signal for the fuel cell power source 30 to share the load current or power at a predetermined ratio (for example, Digital signal IL from current/power signal generating means 6o
80% of this is shared and a digital signal of 0.8IL is sent to the digital signal comparing means 91). The fuel cell power supply output current/power signal generation means 70 detects the output current or power of the fuel cell power supply, converts it into a digital signal, and then sends this digital signal to the digital signal comparison means 91. As a result, the following operations are similar to those described in the first embodiment shown in FIG.
The digital signal output from the load sharing setting means 80 is compared with the digital signal output from the load sharing setting means 80, and the digital signal corresponding to the difference is converted to the D/A converting means 92.
Send to. The D/A conversion means 92 converts the digital signal output from the digital signal comparison means 91 into an analog signal, and converts this analog signal into an output voltage setting provided in the output voltage constant voltage control circuit 21-2 of the switching power supply device. Add to section. Output voltage constant voltage control circuit 21-2
Then, an analog signal is received from the D/A conversion means 92, and the output voltage of the switching power supply device 21 is changed. That is, by raising or lowering the level of the analog signal sent from the D/A conversion means 92, the output voltage of the switching power supply 21 is increased or decreased, thereby increasing or decreasing the load current of the switching power supply 21 or the share of power. It can be increased or decreased.

Further, the fuel cell power supply output current/31 force signal generating means 7
0. Digital signal comparison means 91. Since a null feedback loop is constructed from the D/A conversion switching power supply main circuit 21-1, the fuel cell power supply output current/power signal generation means 70 outputs the fuel cell type [30, that is, the switching power supply Output voltage control is performed to bring the digital signal corresponding to the output current or power of 21 closer to the digital signal sent from the load sharing setting means 80. That is, output voltage control is performed to match the output current or power of the switching power supply 21 with the current set by the load sharing setting means.In this embodiment, the output capacity of the fuel cell power supply 30 is To cope with the case where the load current exceeds the current or power that can be supplied by the fuel cell power supply 30 when the value is selected to be less than the minimum value or between the peak value and the minimum value of the current or power consumption of the fluctuating load. By setting the upper limit of the current or power set by this load sharing setting means 80 to the rated output current or power of the switching power supply 21, the load current or power shared by the fuel type/lI2 power supply 30 is set up to the rated output, The output exceeding the rated output can be assigned to the rectifier 5.

Since the fourth embodiment is configured and operates as described above, the current or power set by the load sharing setting means 80 is supplied from the fuel cell power source 30, and the load sharing setting means 80
For the amount of current or power exceeding the set value, power can be supplied from the rectifier 5 that rectifies the commercial power supply 4. Therefore, when processing digital signals in the digital signal comparing means 91 and the load sharing setting means 80, for example, maintenance can be performed by using a personal computer and inputting the load current or power to be shared by the fuel cell power source 30 from the keyboard. This allows a person to easily perform load sharing control between the fuel cell power source and the rectifier.

Therefore, when installing the system, when performing an operation test on each of the fuel cell power source 30 and the rectifier 5 up to the rated power of 8, even if the capacity of the test load is not sufficient, it is necessary to install the system according to the capacity of the test load. There is no need to separately shut down the fuel cell type #30 and the rectifier 5 or to separately disconnect the power supply lines for each output, and the test can be performed efficiently and quickly. Furthermore, even when the power consumption of the load 100 is lower than initially predicted and is always maintained within the rating of the fuel cell power source 30 after the introduction of the fuel cell DC parallel operation system, abnormal conditions in the equipment can be detected early. Therefore, it is possible to easily check the normality of the commercial power supply system in the power supply state. In this way, even if the load current or power is smaller than the rated output current or power of the fuel cell power source 30, the load can be shared by the rectifier 5, and even when performing an operation test of the rectifier 5 or an operation check of the commercial power supply system. It can be easily implemented.

FIG. 5 is a block diagram illustrating a fifth embodiment of the present invention, and the same reference numerals as those in the fourth embodiment in FIG. 4 have the same functions. The fifth embodiment in FIG. 5 is the fourth embodiment in FIG.
What differs from the embodiment is the intervening load sharing setting means 80.
are inserted at different points. In this embodiment, at the input of the digital signal comparison means 91, the digital signal from the fuel cell power supply output current/power signal generation means 70 is inputted to the fuel cell power supply 30 to bear the load current or power at a predetermined ratio. A load sharing setting means 80 is interposed to convert the data into a digital signal for use.

The embodiment configured as described above also operates and functions in the same manner as the fourth embodiment shown in FIG. 4 described above, and its operation and effect will be described below.

Current/power signal generation means 60 detects load current or power, A/D converts this analog signal into a digital signal, and sends a digital signal corresponding to the load current or power to digital signal comparison means 91. The fuel cell power supply output current/power signal generation means 70 detects the output current or power of the fuel cell power supply, A/D converts it into a digital signal, and then sends this digital signal to the load sharing setting means 80. The load sharing setting means 80 receives the digital signal from the fuel cell power supply output current/power signal generation means 70 and transmits this signal to the fuel cell power supply 30.
Converts into a digital signal to share load current or power at a predetermined ratio. For example, fuel cell layer #current/
It receives the digital signal 1d from the power detection means 70, multiplies it by 111, and sends the digital signal 1.1IId to the digital signal comparison means 91. By doing this, there is a feedback loop that will be described later, so the current/i
If the digital signal from the f-force signal generating means 60 is IL, then 1.11 Id=IL, therefore Id=o, 9
IL, and the fuel cell power source can share 90% of the load current. The digital signal comparing means 91 compares the digital signals output from the load sharing setting means 80 and the current/power signal generating means 60, and converts the digital signal corresponding to the difference to the D/A converting means 92.
Send to. The D/A conversion means 92 converts the digital signal output from the digital signal comparison means into an analog signal, and converts this analog signal into an output voltage setting provided in the output voltage constant voltage control circuit 21-2 of the switching power supply 21. Connect as if adding to the section.

The output voltage constant voltage control circuit 21-2 receives an analog signal from the D/A conversion means 92, and outputs the analog signal from the switching power supply device 2.
Change the output voltage of 1. That is, the D/A conversion means 92
By raising or lowering the level of the analog signal sent from the switching power supply 21, the output voltage of the switching power supply 21 can be raised or lowered, thereby amplifying the load current or power sharing ratio of the switching power supply 21.

Furthermore, fuel cell power supply output current/power signal generation means 70
．． Load sharing setting means 80. Digital signal comparison means 91
．． D/A conversion means 92. Output voltage constant voltage control circuit 21-
2. Since a feedback loop consisting of the switching power supply main circuit 21-1 is configured, the output voltage is adjusted to bring the digital signal sent from the load sharing setting means 80 closer to the digital signal sent from the current/power signal generation means 60. Control will take place. That is, output voltage control is performed to match the output current or power of the switching power supply device 21 to the current or power set by the load sharing setting means 80, which is similar to the fourth embodiment shown in FIG. act.

FIG. 6 is a block diagram illustrating a sixth embodiment of the present invention, and the same reference numerals as those of the fourth embodiment in FIG. 4 have the same functions. The sixth embodiment in FIG. 6 is the fourth embodiment in FIG.
The difference from the above-mentioned embodiment is that the fuel cell DC parallel operation system supplies power to two systems, that it is equipped with two systems of rectifiers that rectify the commercial power supply in order to correspond to each load, and that the fuel cell The detection means for detecting the current or power supplied to the load by the DC parallel operation system individually detects the load current of each load system and adds these to generate a current/ii force signal generation means. In other words, two systems, 100-1 and 100'-2, are targeted as loads, and two systems, 5-1° and 5-2, are equipped with rectifiers to rectify the commercial power supply corresponding to the respective two loads. To prevent backflow between the rectifier 5-1 and the fuel cell power R30 (to prevent the rectifier 5-1 from supplying power to the load 100-2 and the rectifier 5-2 to supply power to the load 100-1)
diodes 311 and 312 to configure a fuel cell DC parallel operation system, and a current/power signal generation means for detecting the current or power supplied to the load by the fuel cell DC parallel operation system and converting it into a digital signal. , current detecting means 60-1, 60-2 connected to the power supply lines of the respective systems to the loads 100-1 and 100-2, and an adder 63 for adding these outputs.

It is clear that even with this configuration, the same operation and effect as in the fourth embodiment shown in FIG. 4 described above is performed. Note that backflow may not be prevented depending on the output voltage characteristics of the rectifiers 5-1 and 5-2 and the design conditions of voltage drop distribution due to the impedance of the feeder line connecting the rectifiers 5-1, 5-2 and the fuel cell power source 30 in parallel. Therefore, the diode for backflow prevention can be omitted, and when configuring a fuel cell DC parallel operation system, it is not necessary to include the diode 311.
．． 312 is not required.

Note that the commercial power source 4 in each of the above embodiments may be another power generation source such as an engine generator.

In addition, the configuration in which two systems of loads and rectifiers are provided as in the sixth embodiment, in each of the first to fifth embodiments,
By using a means for adding up the load current or power for each system, the present invention can be similarly applied to any of them. As described above, the present invention can be applied in various ways and can take various embodiments in accordance with its gist.

[Effects of the Invention] As is clear from the above description, according to the fuel cell DC parallel operation system of the present invention, a fuel cell power source that supplies power to a load by converting the DC output of a fuel electric or other device into voltage using a switching power supply device can be used. When applied to a power source with a variable load, if the load current or power is within the rating of the fuel cell power source, the fuel cell power source will share the entire load, and if it exceeds the rating, the fuel cell power source will share at least the rated load. As a result, it is possible to set a fuel cell power supply that matches the power consumption of the load, reducing the cost of creating a fuel cell energy 7 system, and since load sharing is digitally controlled, a personal computer can be used as a control means. This makes it possible to easily change the load sharing ratio of the fuel cell power source and the rectifier by digital operation, and to check the operation of the commercial power supply system including the fuel cell power source and the rectifier. Installation can be carried out easily and quickly at any time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
FIG. 3 is a block diagram showing a second embodiment of the invention, FIG. 3 is a block diagram showing a third embodiment of the invention, FIG. 4 is a block diagram showing a fourth embodiment of the invention, and FIG. 5 is a block diagram showing a fifth embodiment of the present invention, and FIG. 6 is a block diagram showing a sixth embodiment of the present invention.
FIG. 7 is a block diagram of a conventional fuel cell DC parallel operation system, and FIG. 8 shows the output voltage of a conventional DC power supply device or a switch-noting power supply device according to an embodiment of the present invention. FIG. 2 is a circuit configuration diagram showing an example of a constant voltage control circuit. DESCRIPTION OF SYMBOLS 1... Fuel cell, 4.4-1.4-2... Commercial power supply, 5.5-1.5-2... Rectifier, 10... Drive control circuit including a pulse width modulation circuit, 11... operational amplifier, 12.13, 14.17.18... resistor, 15...
・Zener diode, 16.19... diode,
21...Switching power supply device, 21-1...Switching power supply device main circuit, 21-2...Output voltage constant voltage control circuit, 30-...Fuel cell power supply, 60...Current/power signal generation Means, 60-1. 60-2... Load system - current/power signal generation means, 61... Rectifier output current/power signal generation means, 62. 63... Adder, 70... Fuel cell power supply Output current/power signal generation means,
74... Subtractor, 80... Load sharing setting means, 91
...Digital signal comparison means, 92...D/A conversion means, 100,100-1.100-2...Load, 3
11.312...Diode.

Claims (6)

[Claims] (1) It has a fuel cell power source consisting of a fuel cell and a DC power supply device that receives the output of this fuel cell as input, and uses the output of this fuel cell power source and AC power output from a commercial power source or other power generation source. In a fuel cell DC parallel operation system that supplies power to a load by connecting the output of a rectifier in parallel with the output of a rectifier that rectifies the Current/power signal generation means detects the current or power supplied to the load by the parallel operation system and outputs a corresponding digital signal; and detects the current or power supplied to the load by the fuel cell power source and responds to the detected current or power. a fuel cell power supply output current/power signal generation means for outputting a digital signal; a digital signal outputted from the fuel cell power supply output current/power signal generation means; and a digital signal outputted from the current/power signal generation means. a digital signal comparing means for comparing and outputting a digital signal according to the difference; and a D/A converting means for converting the digital signal output from the digital signal comparing means into an analog signal; An analog signal output from the means is connected to an output voltage setting section provided in the switching power supply output voltage constant voltage control circuit, and the output voltage of the switching power supply is applied to the output voltage of the fuel cell DC parallel operation system when the fuel cell DC parallel operation system is loaded. A direct current parallel fuel cell, characterized in that the ratio of load sharing of the output of the fuel cell power source is controlled by controlling according to fluctuations in the current or power supplied to the rectifier or fluctuations in the output voltage of the rectifier. driving system. (2) In the fuel cell DC parallel operation system according to claim 1, the current/power signal generation means includes an addition means, and a rectifier that rectifies AC power output from a commercial power source or another power generation source supplies the load to the load. The current or power supplied to the load by the fuel cell power supply is detected, and the current or power supplied to the load by the fuel cell power supply is added to the current or power supplied to the load by the rectifier, and the current or power supplied to the load by the fuel cell power supply is added. A fuel cell DC parallel operation system characterized in that the fuel cell DC parallel operation system outputs a digital signal corresponding to the current or power supplied to a load. (3) In the fuel cell DC parallel operation system according to claim 1, the fuel cell power supply output current/power signal generation means includes a subtraction means, and the current or electric power supplied to the load by the fuel cell DC parallel operation system and the commercial A rectifier that rectifies AC power output from a power source or other power generation source detects the current or power supplied to the load, and the rectifier rectifies the current or power supplied to the load by the fuel cell DC parallel operation system. A fuel cell DC parallel operation system characterized in that the fuel cell power supply outputs a digital signal corresponding to the current or power supplied to a load by reducing the supplied current or power. (4) In the fuel cell DC parallel operation system according to any one of claims 1 to 3, during the connection for inputting the digital signal from the current/power signal generating means to the digital signal comparing means, the digital signal is A fuel cell direct current parallel operation system characterized by interposing a load sharing setting means for converting the fuel cell power source into a digital signal for sharing load current or power at a predetermined ratio. (5) In the fuel cell DC parallel operation system according to any one of claims 1 to 3, during the connection for inputting the digital signal from the fuel cell power supply output current/power signal generation means to the digital signal comparison means, the 1. A fuel cell direct current parallel operation system comprising a load sharing setting means for converting a digital signal into a digital signal for the fuel cell power source to share load current or power at a predetermined ratio. (6) In the fuel cell direct current parallel operation system according to any one of claims 1 to 5, the loads are divided into a plurality of systems, and the commercial power supply or other power generation source outputs an output corresponding to each load. A rectifier is provided to rectify the alternating current power supplied to each of the loads, and when detecting the current or power supplied to each of the loads, an adding means is provided to add and detect the detected values for each of the systems, and the fuel cell power source is A fuel cell direct current parallel operation system characterized in that the output of is supplied to each of the loads via a backflow prevention means.