JPH0745298A - Power supply device utilizing fuel cell - Google Patents

Abstract

PURPOSE:To improve generating efficiency while surely preventing sintering a cell catalyst by providing a connecting condition control means, detecting output voltage of a fuel cell and controlling an adjusting means so that this detected output voltage obtains a preset value or less. CONSTITUTION:A preset voltage value is set to a permissible upper limit voltage value capable of preventing sintering a catalyst. Power consumption of an external load H is decreased, and an output voltage value of a fuel cell 1, when arriving at a preset voltage value, is detected by a control unit C utilizing a microcomputer through a voltage detector 13. A switchgear 6 for adjusting a connecting condition of an output line 3 to a dummy load means 4 is controlled so as to obtain output voltage in the preset output voltage value or less. Accordingly, a trouble, that the output line 3 is connected to the means 4 regardless of the output voltage not reaching the permissible upper limit value to unnecessarily consume output power of the cell 1 by the means 11, is avoided to enable generating efficiency to improve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an external load connected to an output line of a quadrature conversion device for converting output DC power of a fuel cell into AC power, and adjusts a connection state between the output line and the pseudo load means. The present invention relates to a fuel cell power supply device provided with an adjusting unit.

[0002]

2. Description of the Related Art The output voltage / current characteristics of a fuel cell are shown in FIG.
As shown in, the output voltage V decreases as the output current I _o decreases.
_Shows the property that _o increases. On the other hand, in the phosphoric acid type fuel cell, when the output voltage becomes excessive, the catalyst of the cell of the fuel cell causes sintering, the surface area of the catalyst becomes small, and the characteristics of the fuel cell deteriorate. Therefore, in such a power supply device using a fuel cell, conventionally, in order to prevent the catalyst of the cell from sintering, the allowable lower limit of the allowable upper limit voltage value V _L of the fuel cell for preventing the sintering of the catalyst is conventionally used. The current value I _L is set based on the output voltage / current characteristics shown in FIG. 3, and the output current I _{o of the} fuel cell is set.
Is provided, and the output current I _o of the fuel cell is reduced as the power consumption in the external load is reduced based on the detection information of the current detection means to reach the allowable lower limit current value I _L. When it reaches, the adjusting means is controlled so as to connect the output line and the pseudo load means so that the output current I _o of the fuel cell becomes the allowable lower limit current value I _L or more.
Although the fuel cell is configured by connecting a plurality of cells in series, the permissible upper limit voltage value V _L is the permissible upper limit voltage value of one cell for preventing sintering of the catalyst (for example,
0.8 V).

[0003]

By the way, the fuel cell is
Output voltage V after deterioration with time_oDecreases with time,
For example, as shown in FIG.
What showed the force voltage / current characteristics, but time passed
And the output voltage / current characteristics shown by the alternate long and short dash line
It Therefore, in the conventional device, the output current I of the fuel cell is_o
Is the allowable lower limit current value I _LAdjust the adjustment means to be above
Output voltage V_oIs the allowable upper limit voltage value V_LReached
Output line and pseudo load means despite not
May be connected, in which case the fuel cell output
Power is unnecessarily consumed by the pseudo load means, and as a result,
There is a problem that the power generation efficiency decreases.

The present invention has been made in view of the above circumstances, and an object thereof is to improve the power generation efficiency while surely preventing the sintering of the catalyst of the cell of the fuel cell.

[0005]

A first characteristic configuration of a power supply device using a fuel cell according to the present invention is provided with voltage detection means for detecting an output voltage of the fuel cell, and the detection information of the voltage detection means is provided. Based on this, connection state control means for controlling the adjusting means is provided so that the output voltage of the fuel cell becomes equal to or lower than the set voltage value.

A second characteristic configuration is a power detecting means for detecting output power to the external load from the orthogonal converter, and an output to the external load so that the output voltage of the fuel cell becomes equal to or lower than the set voltage value. Output control means for increasing the power is provided, the connection state control means, based on the detection information of the power detection means, when the increase adjustment of the output power by the output control means is a set limit,
It is configured to control the adjusting means so as to connect the output line and the pseudo load means.

[0007]

The operation of the first characteristic structure is as follows. The set voltage value is set to an allowable upper limit voltage value for preventing sintering of the catalyst. When the output voltage of the fuel cell increases and reaches the set voltage value as the power consumption in the external load decreases, the connection state control means outputs the output voltage of the fuel cell so that the output voltage becomes equal to or less than the set voltage value. The adjusting means is controlled to connect the line and the pseudo load means.

The operation of the second characteristic structure is as follows. When the output voltage of the fuel cell increases and reaches the set voltage value as the power consumption in the external load decreases, when the increase adjustment of the output power to the external load does not reach the set limit, the output control means When the output power to the external load is increased and adjusted so that the output voltage of the battery is equal to or lower than the set voltage value, and the increase of the output power to the external load is within the set limit, the output of the fuel cell is output by the connection state control means. The adjusting means is controlled so as to connect the output line and the pseudo load means so that the voltage becomes equal to or lower than the set voltage value.

[0009]

According to the first characteristic configuration, the output line and the pseudo load means are connected only when the output voltage of the fuel cell becomes equal to or higher than the allowable upper limit voltage value. As described above, even if the output voltage does not reach the allowable upper limit voltage value, the output line and the pseudo load means are connected, and the output power of the fuel cell is unnecessarily consumed by the pseudo load means. As a result, it is possible to surely avoid, and as a result, it is possible to improve the power generation efficiency while surely preventing the sintering of the catalyst of the cell of the fuel cell.

Further, according to the second characteristic configuration, when the external load capable of adjusting the increase / decrease of the input power is connected to the output line of the orthogonal converter, the increase adjustment of the output power with respect to the external load is set. Since the output line and the pseudo load means are connected only when the limit is reached, the power generation efficiency can be further improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, the overall configuration of a power supply device using a fuel cell will be described with reference to FIG. Reference numeral 1 in the figure is a phosphoric acid type fuel cell, and this fuel cell 1 is configured to generate DC power by an electrochemical reaction between oxygen in the air supplied from the outside and hydrogen in the fuel gas. is there. Although not shown, in a reformer (not shown), a raw fuel gas such as natural gas is subjected to a reforming reaction with steam supplied from a steam separator (not shown) to make hydrogen gas a main component. It is configured to generate the fuel gas to be supplied and to supply the generated fuel gas to the fuel cell 1.

Reference numeral 2 in the drawing is an inverter as an orthogonal converter for converting the output DC power of the fuel cell 1 into AC power, and the output line 3 of this inverter 2 has an external load H,
A plurality of dummy heaters 4 having the same power consumption and an auxiliary device 5
Are connected in parallel. In the figure, 6 is a switchgear that opens and closes between the output line 3 and the dummy heater 4, and 7 is an output line 3
Is an opening / closing device for opening / closing between the output line 3 and the auxiliary equipment 5, and 8 is an opening / closing device for opening / closing between the output line 3 and the auxiliary equipment 5. Auxiliary machine 5
Is composed of a blower for supplying air to the fuel cell 1, a pump for supplying cooling water to the fuel cell 1, and the like. Although not shown, the dummy heater 4 is provided in the steam separator to heat the water in the steam separator. The dummy heater 4 corresponds to a pseudo load means, and the switchgear 6 functions as an adjusting means for adjusting the connection state between the output line 3 and the dummy heater 4.

The output line 10 of the commercial power source 9 is connected to the external load H.
And is configured to supply electric power to the external load H by the interconnection of the power supply device according to the present invention and the commercial power supply 9. Further, the output line 10 of the commercial power source 9 is connected to the auxiliary device 5, and the auxiliary power source 5 is configured to be supplied with power from the commercial power source 9 during the start-up operation of the power supply device. In the figure, 11 is a switchgear that opens and closes between the output line 10 of the commercial power source 9 and the external load H, and 12 is a switchgear that opens and closes between the output line 10 of the commercial power source 9 and the auxiliary equipment 5. .

In the figure, 13 is the output voltage V of the fuel cell 1.
A voltage detector as a voltage detecting means for detecting _O , 14 is a first current detector for detecting the output current I _O of the fuel cell 1,
Reference numeral 15 is an output current I from the inverter 2 to the external load H.
It is the 2nd current detector which detects _H. Therefore, the second current detector 15 functions as power detection means for detecting the output power P from the inverter 2 to the external load H. or,
Reference numeral 16 in the figure is a proportional valve for adjusting the amount of fuel gas supplied to the fuel cell 1.

C in the figure is a control device using a microcomputer, and this control device C controls various controls of the power supply device. The control operation of the controller C will be described below. First, the control operation in the start-up operation in which the power supply device is brought into a state capable of generating power will be described.

In the start-up operation, the switchgear 6, 7, 8 is switched to the open state and the switchgear 12 is switched to the closed state. Therefore, electric power is supplied from the commercial power source 9 to the auxiliary device 5.

Then, in the steady operation after the start-up operation is completed, the switchgear 8 is switched to the closed state and the switchgear 12 is switched to the open state from the state of the start-up operation. Further, the proportional valve 16 is opened to supply the fuel gas to the fuel cell 1. Therefore, the direct-current power generated by the fuel cell 1 is converted into alternating-current power by the inverter 2, and the alternating-current power is supplied to the auxiliary device 5 to execute the self-sustaining operation. Then, the switchgear 7 is switched to the closed state based on a power transmission command from the outside. Therefore, the output AC power from the inverter 2 is supplied to the external load H. The switchgear 11 is switched to the closed state based on an interconnection operation command from the outside. In the interconnection operation, the output voltage V _H from the inverter 2 is synchronized with the output voltage of the commercial power source 9.

In the steady operation, the opening degree of the proportional valve 16 is adjusted based on the detection information from the first current detector 14. That is, an amount of fuel gas commensurate with the output power of the fuel cell 1 is supplied.

Next, the control operation for maintaining the output voltage V _O of the fuel cell below the set voltage value, which is a characteristic configuration of the present invention, will be described based on the flowchart shown in FIG. The set voltage value is, for example, as shown in FIG. 3, an allowable upper limit voltage value V _L for preventing sintering of the catalyst.
Set to.

In step # 1, it is determined based on the detection information of the voltage detector 13 whether the output voltage V _O of the fuel cell 1 is the set voltage value V _L or more. When the output voltage V _O is equal to or higher than the set voltage value V _L , it is determined in step # 2 based on the open / close state of the switchgear 11 whether or not the interconnection operation is being performed. If not, the step is performed. In # 8, one switchgear 6 is switched to the closed state, and the total dummy power consumption P _D of the dummy heater 4 is the power consumption of one dummy heater 4 (hereinafter referred to as unit dummy power consumption) ΔP _D. After incrementing, go back to step # 1.

If it is determined in step # 2 that the interconnection operation is being performed, then in step # 3, the second current detector 1
Based on the detection information of No. 5, it is determined whether the increase adjustment of the output power P with respect to the external load H is within the set limit. That is, the upper limit output power value P _L that can be output to the external load H, and the second
The output current I _H detected by the current detector 15 and the inverter 2
It is determined whether or not the difference between the output voltage V _H and the output power P calculated by the above is a minimum unit ΔP capable of adjusting the output power with respect to the external load H.

When it is determined in step # 3 that the increase adjustment of the output power P is within the set limit, that is, when the difference between the upper limit output power value P _L and the output power P is smaller than the minimum output power adjustment unit ΔP. In step # 8, one switchgear 6 is switched to the closed state, and the total dummy power consumption P _D is increased by the unit dummy power consumption ΔP _D.
Return to 1.

In step # 3, when it is determined that the increase adjustment of the output power P is not within the set limit, that is, when the difference between the upper limit output power value P _L and the output power P is the output power adjustment minimum unit ΔP or more. In step # 4, it is determined whether the total power consumption P _D of the dummy heater 4 is zero, that is, whether at least one dummy heater 4 is connected to the output line 10.

If it is determined in step # 4 that the total dummy power consumption P _D is not zero, the output power P for the external load H is set to the minimum output power adjustment unit ΔP and unit dummy power consumption Δ in step # 5. It is determined whether or not it is possible to perform the increase adjustment by the amount of adding P _D, and when it is determined that it is possible, the output voltage V _H of the inverter 2 is determined from the output voltage of the commercial power source 9 in step # 6. Also, the output power P is adjusted to be increased by (ΔP + ΔP _D ), and then, in step # 7, one switchgear 6 is switched to the open state to reduce the total dummy power consumption. After reducing P _D by the unit dummy power consumption ΔP _D , the process returns to step # 1.

When it is determined in step # 4 that the total dummy power consumption P _D is zero, or in step # 5,
When it is determined that the output power P with respect to the external load H cannot be increased and adjusted by (ΔP + ΔP _D ), in step # 9, the output voltage V _H of the inverter 2 is made slightly higher than the output voltage of the commercial power supply 9. To increase the output power P by the minimum output power adjustment unit ΔP, and then returns to step # 1.

That is, when the output voltage V _O exceeds the set voltage value V _L , steps # 3 to # 7, and
In step # 9, the output voltage V _O is the set voltage value V _L
As will be described below, the output power P for the external load H is preferentially increased and adjusted, and the number of dummy heaters 4 connected to the output line 10 is reduced as much as possible to reduce the total dummy power consumption P _D. Control to do so.

The above-described control of steps # 1 to # 9 is continued until it is determined in step # 1 that the output voltage V _O has become smaller than the set voltage value V _L.

Therefore, using the control device C, the output voltage V of the fuel cell 1 is determined based on the detection information of the voltage detector 13.
_The connection state control means 101 for controlling the opening / closing of the switchgear 6 so that _O becomes equal to or less than the set voltage value V _L , and the fuel cell 1
The output control means 102 is configured to increase and adjust the output power P to the external load H so that the output voltage V _{O of the above} is less than or equal to the set voltage value V _L.

[Other Embodiments] In the above embodiment, the present invention is
The present invention has been applied to the case where power is supplied to the external load H through the interconnection of the power supply device using the fuel cell and the commercial power supply 9. However, instead of this, the present invention is externally provided by the power supply device using the fuel cell alone. It can also be applied to the case of supplying power to the load H. In this case, when the external load H can increase or decrease the input power, the output power P to the external load H is preferentially increased and adjusted so that the output voltage V _O becomes equal to or lower than the set voltage value V _L. Control is performed to reduce the total dummy power consumption P _D by reducing the number of dummy heaters 4 connected to the output line 10 as much as possible. In addition, external load H
If the input power cannot be increased or decreased, the output voltage V _O
The opening / closing control of the opening / closing device 6 is performed so that the voltage becomes equal to or less than the set voltage value V _L.

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

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply device using a fuel cell according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flowchart of control operation.

FIG. 3 is a diagram showing output voltage / current characteristics of a fuel cell.

[Explanation of symbols]

 1 Fuel Cell 2 Orthogonal Converter 3 Output Line 4 Pseudo Load Means 6 Adjusting Means 13 Voltage Detecting Means 15 Electric Power Detecting Means 101 Connection State Control Means 102 Output Control Means H External Loads

Claims (2)

[Claims] 1. An external load (H) is connected to an output line (3) of a quadrature conversion device (2) for converting output DC power of a fuel cell (1) into AC power, and the output line (3) is simulated. A power supply device using a fuel cell provided with an adjusting means (6) for adjusting a connection state with a load means (4), wherein a voltage detecting means (13) for detecting an output voltage of the fuel cell (1) is provided. A connection state control means (which is provided and controls the adjusting means (6) so that the output voltage of the fuel cell (1) becomes equal to or less than a set voltage value based on the detection information of the voltage detecting means (13). 101) is provided, the power supply device using a fuel cell. 2. Power detection means (1) for detecting output power from the orthogonal transformation device (2) to the external load (H).
5) and output control means (102) for increasing and adjusting the output power to the external load (H) so that the output voltage of the fuel cell (1) becomes equal to or less than the set voltage value,
The connection state control means (101), based on the detection information of the power detection means (15), the output control means (1).
02) is configured to control the adjusting means (6) so as to connect the output line (3) and the pseudo load means (4) when the increase adjustment of the output power is within a set limit. A power supply device using a fuel cell according to claim 1.