JP2003243011A - Fuel cell power generating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power generating system efficiently supplying power for an accessory of a separate line from a system power line output. <P>SOLUTION: This fuel cell power generating system is equipped with a fuel cell 12 generating power by electrochemical reaction of fuel gas 19 with an oxidizing agent gas 14; a DC/DC converter transforming DC voltage outputted from the fuel cell 12; a DC/AC inverter 22 connected to the output side of the DC/DC converter 20 converting DC voltage transformed with the DC/DC converter 20 into AC voltage in order to link with a system power source 36; an accessory power terminal 25 supplying power to accessories 30, 31, and 32 for the fuel cell 12; and a change over circuit 44 changing over the accessory power terminal 25 between the output side of the fuel cell 12 and the output side of the DC/AC inverter 22. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generation system, and more particularly to a fuel cell power generation system for efficiently supplying auxiliary power such as a pump and a blower for driving the fuel cell power generation system.

[0002]

2. Description of the Related Art A conventional fuel cell power generation system uses a commercial power supply from the start of the power generation system until the operation of the fuel cell is established in order to supply power to auxiliary equipment such as a pump and a blower for driving the power generation system. The power for the auxiliary equipment was supplied from the system power supply. Further, after the power generation system shifts to the operating state of the fuel cell, a part of the electric power generated from the fuel cell is used to supply the power source for the auxiliary equipment.

FIG. 4 is a block diagram of a conventional fuel cell power generation system. The conventional fuel cell power generation system includes a fuel cell 12, a DC / DC converter 20, and a DC / AC.
An inverter 22, an AC / DC stabilized power supply circuit, an auxiliary machine 30, an auxiliary machine 31, and an auxiliary machine 32 are provided, and a load is applied from the start of the fuel cell power generation system until the operation of the fuel cell is established. 38 from the system power supply 36 that supplies power to the auxiliary power supply 38 via the AC / DC stabilized power supply circuit 24,
Auxiliary equipment 31 with DC / DC converter 26, DC / DC
The power for the auxiliary machine was supplied to the auxiliary machine 32 with the converter 28.

Further, after the fuel cell power generation system has transitioned to a state where the fuel cell operation is maintained, the system power source 3
In place of 6, the DC power generated from the fuel cell 12 is D
The AC power output via the C / DC converter 20 and the DC / AC inverter 22 is again passed through the AC / DC stabilized power supply circuit 24, the auxiliary device 30, the auxiliary device 31 with the DC / DC converter 26, the DC / DC. It was supplied to the auxiliary machine 32 with the converter 28 as electric power for the auxiliary machine.

[0005]

However, in such a conventional fuel cell power generation system, the electric power generated by the fuel cell 12 is supplied to the auxiliary equipment via the DC / DC converter 20 and the DC / AC inverter 22. Therefore, a power loss corresponding to the power conversion efficiency of these converters has occurred. In addition, from the fuel cell 12 to the DC / DC converter 20, DC
The voltage drop caused by the wiring length up to the auxiliary machine via the / AC inverter 22 was also a power loss.

[0006] Therefore, an object of the present invention is to provide a fuel cell power generation system in which wasteful power loss of an auxiliary power source is suppressed and power generation efficiency is improved.

[0007]

In order to achieve the above object, a fuel cell power generation system according to a first aspect of the invention is a fuel cell power generation system 3 as shown in FIG.
Reference numeral 9 denotes a fuel cell 12 that generates electricity by an electrochemical reaction between a fuel gas 19 and an oxidant gas 14, and a DC / D that transforms a DC voltage output from the fuel cell 12 into a predetermined DC voltage.
In order to connect to the C converter 20 and the output side of the DC / DC converter 20, and to connect to the system power supply 36,
A DC / AC inverter 22 for converting a DC voltage transformed by the DC converter 20 into an AC voltage, and auxiliary devices 30, 3
Auxiliary machine power terminal 25 for supplying electric power to 1, 32 and a switching circuit 45 for switching the auxiliary machine power terminal 25 between the output side of the fuel cell 12 and the output side of the DC / AC inverter 22.
And

Here, the fuel cell 12 is typically a polymer electrolyte fuel cell, and the system power source 36 is a single-phase three-wire system 1.
It includes commercial power sources such as 00 / 200V and single-phase 200V.

With this configuration, at the time of starting the fuel cell power generation system, the auxiliary equipment 3 is moved from the system power source 36 side.
Electric power for 0, 31, 32 can be supplied, and thereafter, as the power generation of the fuel cell 12 starts, electric power for the auxiliary machines 30, 31, 32 can be supplied from the output line of the fuel cell 12.

In order to achieve the above object, a fuel cell power generation system according to a second aspect of the invention is a fuel cell power generation system according to the first or second aspect of the invention, as shown in FIG. AC / D is provided between the output side of the grid interconnection inverter 22 and the switching circuit 44.
A C-stabilized power supply circuit 24 is provided.

According to this structure, at the time of starting the fuel cell power generation system, the AC / D
Auxiliary equipment 30, 31, 32 via the C stabilized power supply circuit 24
Power for the auxiliary devices 30, 31, 32 can be supplied from the output line of the fuel cell 12 with the start of power generation of the fuel cell 12.

To achieve the above object, a fuel cell power generation system according to a third aspect of the present invention is, for example, as shown in FIG. 3, in the fuel cell power generation system according to the first aspect, an output side of the fuel cell 12 is provided. Between the switch circuit 44 and
A C / DC stabilized power supply circuit 50 is provided.

With this configuration, at the time of starting the fuel cell power generation system, the auxiliary equipment 3 is moved from the system power source 36 side.
It is possible to supply electric power for 0, 31, 32, and thereafter, when the power generation of the fuel cell 12 is started, the auxiliary machines 30, 31 are output from the output line of the fuel cell 12 via the DC / DC stabilized power supply circuit 50. , 32 can be stably supplied.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same or corresponding members are designated by the same reference numerals or similar symbols, and duplicated description will be omitted.

FIG. 1 is a block diagram of a fuel cell power generation system according to a first embodiment of the present invention. The fuel cell power generation system 39 includes a fuel cell 12 that generates electricity by an electrochemical reaction between a fuel gas 19 containing hydrogen and an oxidant gas 14 containing air or oxygen, and a direct current of about 50 V output from the fuel cell 12. A DC / DC converter 20 for transforming the voltage into a predetermined DC voltage of about 300V, and a DC
Connected to the output side of the DC / DC converter 20 and connected to the system power supply 3
6, a DC / AC inverter 22 for converting a DC voltage of about 300 V transformed by the DC / DC converter 20 into an AC voltage of 200 V / 50 Hz or 200 V / 60 Hz, and a dual power source for the fuel cell 12. Auxiliary machine power terminal 25 for supplying electric power to the auxiliary machine 30 with the circuit 33, the auxiliary machine 31 with the dual power supply circuit 27, and the auxiliary machine 32 with the dual power supply circuit 29.
And the auxiliary machine power terminal 25 to the output side of the fuel cell 12 and DC
A switching circuit 45 for switching the electric power for auxiliary equipment between the output side of the system interconnection inverter as the AC / AC inverter 22 and
And a main control unit 42.

The main control section 42 is composed of a microprocessor and a control computer, and the fuel cell 1
2. The DC / DC converter 20, the system interconnection inverter as a DC / AC inverter, the switching circuit 45, and the auxiliary machines 30, 31, 32 are controlled by control signals.

The main control unit 42 monitors the output voltage of the fuel cell 12, the output voltage of the DC / AC inverter 22, and the voltage of the system power supply 36, respectively, and supplies power to the load 38. It is possible to control the power generation so that the power supplied from the grid interconnection inverter is synchronized with the grid power supply 36 while comparing the phase and voltage of the AC power.

The fuel cell power generation system 39 has an internal AC
It has a node on the A side associated with the bus and a node on the B side associated with the DC bus, and at the time of start-up, the channel of the switching element or the electromagnetic relay or the semiconductor switching transistor as the switching circuit 45 is the node on the A side of the auxiliary machine power terminal 25. The conduction channel 41 at the node on the A side of the switching circuit 45 is closed so as to electrically connect between and the system power supply 36. At this point, the conduction channel 43 at the B-side node of the switching circuit 45 is open.

In the above embodiment, the switching circuit 45 is used.
AC power was supplied to the AC bus by closing the conduction channel 41 at the node on the A side of the above. Instead of this, DC power is supplied from the output line of the grid interconnection inverter 22 to the DC bus via the diode 7. It can also be supplied.

The auxiliary machine 30 is supplied with electric power through the dual power supply circuit 33 connected to the AC bus, and the auxiliary machine 31 receives the AC power.
Power is supplied through the dual power supply circuit 27 connected to the bus, and the auxiliary machine 32 receives the dual power supply circuit 2 connected to the AC bus.
By receiving the power supply through 9, the system power supply 3
It is possible to receive power supply at the time of starting the fuel cell power generation system 39 from the 6 side.

Here, the dual power supply circuit 33 has two bus inputs, an AC bus input and a DC bus input, and the switching circuit 4
When the AC bus reaches the active state due to 5, A
It is an electric circuit that functions as an adapter that receives an AC power supply from the C bus, rectifies it into a DC voltage, and outputs a DC voltage reduced to the rated voltage of the auxiliary device 30.

When the DC bus reaches the active state by the switching circuit 45, the dual power supply circuit 33 receives a DC power supply from the DC bus and outputs a DC voltage adapted to the rated voltage of the auxiliary machine 30. It is an electric circuit that functions as a DC / DC converter.

Further, the other two power supply circuits 27 and 29 similarly detect the active state of the AC bus and the DC bus, or receive a control signal from the main control unit 42 to switch the AC bus and the DC bus to switch the auxiliary equipment. It is an electric circuit that outputs the rated voltage of 31 and 32.

The power source of the main control unit 42 may rectify the AC voltage of the system power source 36 to supply power when the fuel cell is started. The power source may be supplied from a power storage and discharge system including a battery inside the fuel cell power generation system 39. May be supplied.

When power is supplied from the power storage and discharge system to the main control unit 42, the fuel cell 1
In the second normal operation mode, the power storage and discharge system including the battery can be charged from the output voltage of the fuel cell.

The auxiliary device 30 is a device corresponding to, for example, a blower that supplies the raw fuel 16 and air or oxygen as the oxidant gas 14 to the fuel cell 12, and the auxiliary device 31 is, for example, a cooling device for the fuel cell 12. The auxiliary device 32 is a device corresponding to a pump that circulates water, and the auxiliary device 32 is a device corresponding to a pump that supplies water to the reformer 18, for example.

After starting, the fuel cell power generation system 39 switches the switching element as the switching circuit 45 or the channel of the electromagnetic relay or the semiconductor switching transistor to the auxiliary machine power at the stage of transition to the normal operating state by the control of the main control unit 42. The conduction channel 43 at the B-side node of the switching circuit 45 is closed to electrically connect the B-side node of the terminal 25 and the output side of the fuel cell 12. At this point, the conduction channel 41 at the A-side node of the switching circuit 45 is controlled so as to shift to the open state.

The B-side node of the auxiliary machine power terminal 25 is connected to the DC bus and is configured to supply the DC voltage of the fuel cell 12 to the DC inputs of the two power supply circuits 33, 27 and 29.

In the normal operation, the fuel cell power generation system 39 operates the switching circuit 4 from the output side of the fuel cell 12.
The power generation control is performed by the main control unit 42 while supplying electric power to the auxiliary machines 30, 31, 32 through 5.

Further, the fuel cell power generation system 39 outputs a DC voltage of about 50 V from the fuel cell 12 to DC /
The DC converter 20 performs step-up conversion to a DC voltage of about 300 V, controls the grid-connected inverter as the DC / AC inverter 22, and synchronizes with the grid power supply 36, for example, AC power having a frequency of 50 Hz and a voltage of 200 V is applied to the load 3
Power generation control is performed so that the power is supplied to No. 8.

The system interconnection inverter has a frequency of 50H.
Although an AC voltage of z or 60 Hz and a voltage of 200 V is output, in the present embodiment, an arbitrary frequency and voltage can be selected only by giving a command to the main control unit 48. For example, an AC voltage with a frequency of 60 Hz and a voltage of 200 V, a frequency of 50 Hz and a voltage of 100
When supplying electric power to an AC voltage of V or an electric device as the foreign-purpose load 38, an AC voltage of 110 V can be output.

Electric power for the auxiliary machines 30, 31, 32 is directly supplied from the output side of the fuel cell 12, and therefore DC /
The power loss corresponding to the conversion efficiency of the system interconnection inverter as the DC converter 20 and the DC / AC inverter 22, and the DC / DC converter 20 and the DC / AC inverter 2
Since the voltage drop on the wiring to the auxiliary machine via 2 can be eliminated, the fuel cell power generation system 3 in normal operation
The power generation efficiency of 9 can be improved comprehensively.

Further, in the above-described embodiment, the fuel cell power generation system 39 in the normal operation is configured to supply the electric power directly from the fuel cell 12 to the auxiliary equipment. However, the fuel cell power generation system 39 in the normal operation is operated. The switching circuit 45 may be reconfigured so that the electric power for the auxiliary machines 30, 31, 32 is appropriately supplied from the system power supply 36.

That is, the main control section 42 is
When a state where the electrochemical reaction of the fuel cell 12 is temporarily lowered due to interruption of the supply of the fuel gas 19 or the oxidant gas 14 is detected, or when the output voltage of the fuel cell 12 is abnormally lowered due to overload, If detected, fuel cell 1
Auxiliary equipment 30, 31, 3 until the electrochemical reaction of 2 is restored
The switching circuit 45 is reconfigured so that the electric power for 2 is supplied from the system power supply 36. That is, the power supply system is reconfigured.

FIG. 2 is a block diagram of a fuel cell power generation system according to a second embodiment of the present invention. The fuel cell power generation system 40 includes a fuel gas 19 and an oxidant gas 14
A fuel cell 12 for generating power by an electrochemical reaction with the DC / DC converter 20 for transforming a DC voltage output from the fuel cell 12, for example, about 50 V into a predetermined DC voltage of about 300 V, and a DC / DC converter. 20 is connected to the output side and is connected to the system power supply 36.
The DC voltage of about 300V transformed by the converter 20 is 2
A grid interconnection inverter as a DC / AC inverter 22 for converting to an AC voltage of 00V / 50Hz or 200V / 60Hz, an auxiliary device 30 for the fuel cell 12, and a DC / DC
Auxiliary machine power terminal 25 for supplying electric power to the auxiliary machine 31 with the converter 26 and the auxiliary machine 32 with the DC / DC converter 28
And the auxiliary machine power terminal 25 to the output side of the fuel cell 12 and DC
A switching circuit 44 for switching the power for auxiliary equipment between the output side of the grid interconnection inverter as the AC / AC inverter 22 and
The AC / DC stabilized power supply circuit 24 arranged between the output side of the DC / AC inverter 22 and the switching circuit 44 and the main control unit 42 are provided.

The main control section 42 is composed of a microprocessor and a control computer, as in the above-described embodiment, and includes the fuel cell 12 and the DC / DC converter 2.
0, the system interconnection inverter as a DC / AC inverter, the switching circuit 44, and the auxiliary machines 30, 31, 32.

When the fuel cell power generation system 40 is started, the switching element as the switching circuit 44 or the channel of the electromagnetic relay or the semiconductor switching transistor is electrically connected between the auxiliary machine power terminal 25 and the system power supply 36. Then, the conduction channel at the A-side node of the switching circuit 44 is closed. At this point, the switching circuit 4
The conduction channel at the B-side node of No. 4 is open.

The auxiliary machine 30 is supplied with electric power through the DC bus connected to the auxiliary machine power terminal 25, and the auxiliary machine 31 receives D
Power is supplied from the DC / DC converter 26 connected to the C bus, and the auxiliary machine 32 is supplied with power from the DC / DC converter 28 connected to the DC bus, so that the AC / DC power is supplied from the system power supply 36 side. It is possible to receive power supply at the time of starting the fuel cell power generation system 39 via the DC stabilized power supply circuit 24. It should be noted that the auxiliary machine 30, the auxiliary machine 31, and the auxiliary machine 32 are the same devices as those in the above-described first embodiment, and a description thereof will be omitted.

The AC / DC stabilized power supply circuit 24 includes the auxiliary device 3
It functions as a first DC power supply that supplies a zero rated power supply. The DC / DC converter 26 also functions as a second DC power supply that supplies the rated power of the auxiliary equipment 31 from the first DC power supply. Furthermore, the DC / DC converter 28
Functions as a third DC power supply that supplies the rated power of the auxiliary equipment 32 from the first DC power supply.

As described above, by combining a plurality of stages of DC / DC converters so as to be applied to various rated power supplies of auxiliary machines, each DC / DC converter can be made compact and the number of DC buses can be reduced. Since it can be reduced, the cost of the fuel cell power generation system can be reduced.

After starting, the fuel cell power generation system 40 switches the switching element as the switching circuit 44 or the channel of the electromagnetic relay or the semiconductor switching transistor to the auxiliary machine power at the stage of transition to the normal operating state by the control of the main control unit 42. Terminal 25 and fuel cell 1
The conduction channel at the node on the B side of the switching circuit 44 is closed so as to establish electrical conduction with the output side of 2. In addition,
At this point, the conduction channel at the A-side node of the switching circuit 44 is controlled so as to shift to the open state.

In the normal operation, the fuel cell power generation system 40 controls the power generation by the main control unit 42 while supplying the electric power from the output side of the fuel cell 12 to the auxiliary machines 30, 31, 32 through the switching circuit 44. To do.

The power conversion system inside the fuel cell power generation system 40 can adopt the same system as that of the first embodiment, and therefore its explanation is omitted.

In this embodiment, the auxiliary machines 30, 31, 32 are used.
Power is directly supplied from the output side of the fuel cell 12, so that the DC / DC converter 20 and the system interconnection inverter as the DC / AC inverter 22 and the AC / DC
Power loss and DC corresponding to the conversion efficiency of the inverter 22
/ DC converter 20 and DC / AC inverter 22 and A
Since the voltage drop on the wiring to the auxiliary machine via the C / DC inverter 22 can be eliminated, the power generation efficiency of the fuel cell power generation system 39 during normal operation can be comprehensively improved.

Further, in the above-described embodiment, the fuel cell power generation system 40 in the normal operation is constituted so that the electric power is directly supplied from the fuel cell 12 to the auxiliary equipment. However, the fuel cell power generation system 40 in the normal operation is operated. The switching circuit 44 may be reconfigured so that electric power for the auxiliary machines 30, 31, 32 is appropriately supplied from the system power supply 36.

That is, the main control section 42
When a state where the electrochemical reaction of the fuel cell 12 is temporarily lowered due to interruption of the supply of the fuel gas 19 or the oxidant gas 14 is detected, or when the output voltage of the fuel cell 12 is abnormally lowered due to overload, If detected, fuel cell 1
Auxiliary equipment 30, 31, 3 until the electrochemical reaction of 2 is restored
The switching circuit 45 can be reconfigured so that the power for the power supply 2 is supplied from the system power supply 36.

Further, in order to prevent a momentary interruption of the DC power supply that occurs when switching the switching circuit 44, the AC / DC
A DC voltage is supplied from the stabilized power supply 24 to the DC bus via the diode 7, and the output terminal of the fuel cell 12 is switched to the switch 5
And by connecting to the DC bus via the diode 6,
It is also possible to supply a DC voltage from the fuel cell 12 to the DC bus.

For example, when the switch 5 is closed,
By the switching operation of the switching circuit 44, it is possible to prevent instantaneous interruption of the DC power supply to the auxiliary equipment. On the other hand, when the output voltage of the fuel cell 12 is higher than the DC voltage supplied from the AC / DC stabilized power supply 24, the current is output from the output terminal of the fuel cell 12 by setting the switch 5 to be in the open state. You can also select the option not to supply.

FIG. 3 is a block diagram of a fuel cell power generation system according to a third embodiment of the present invention. The fuel cell power generation system 46 is the DC arranged between the output side of the fuel cell 12 and the switching circuit 44 in the second embodiment.
A / DC stabilized power supply circuit 50 is further provided.

The main control section 48 is composed of a microprocessor and a control computer, as in the above-described embodiment, and includes the fuel cell 12 and the DC / DC converter 2.
0, the system interconnection inverter as a DC / AC inverter, the switching circuit 44, and the auxiliary machines 30, 31, 32.

Since the startup of the fuel cell power generation system 46 can be configured in the same manner as in the second embodiment, its explanation is omitted.

The auxiliary machine 30 is supplied with electric power through the DC bus connected to the auxiliary machine power terminal 25, and the auxiliary machine 31 receives D
Power is supplied from the DC / DC converter 26 connected to the C bus, and the auxiliary machine 32 is supplied with power from the DC / DC converter 28 connected to the DC bus, so that the AC / DC power is supplied from the system power supply 36 side. It is possible to receive power supply at the time of starting the fuel cell power generation system 39 via the DC stabilized power supply circuit 24. It should be noted that the auxiliary machine 30, the auxiliary machine 31, and the auxiliary machine 32 are the same devices as those in the second embodiment, and the description thereof will be omitted.

After starting, the fuel cell power generation system 46 switches the switching element as the switching circuit 44 or the channel of the electromagnetic relay or the semiconductor switching transistor to the auxiliary machine power at the stage of transition to the normal operating state by the control of the main control section 48. Terminal 25 and fuel cell 1
The conduction channel at the B-side node of the switching circuit 44 is closed so as to be electrically conducted to the second output side via the DC / DC stabilized power supply circuit 50. At this point, the conduction channel at the A-side node of the switching circuit 44 is controlled so as to shift to the open state.

During normal operation, the fuel cell power generation system 46 operates from the output side of the fuel cell 12 to DC / DC.
While the electric power is supplied to the auxiliary machines 30, 31, 32 through the switching circuit 44 through the stabilized power supply circuit 50, power generation control is performed by the main control unit 48.

Further, as the power conversion method inside the fuel cell power generation system 46, the same method as that of the first embodiment can be adopted, and therefore the explanation thereof will be omitted.

In this embodiment, the auxiliary machines 30, 31, 32 are used.
Power from the output side of the fuel cell 12 to DC / DC
Since the power is supplied via the stabilized power supply circuit 50, DC /
The power loss corresponding to the conversion efficiency of the system interconnection inverter and the AC / DC inverter 22 as the DC converter 20 and the DC / AC inverter 22, and the DC / DC converter 2
0, the DC / AC inverter 22, and the voltage drop on the wiring to the auxiliary machine via the AC / DC inverter 22 can be eliminated, so that the power generation efficiency of the fuel cell power generation system 39 during normal operation is comprehensively improved. Can be made.

Moreover, even if the DC voltage output from the fuel cell 12 deviates from the predetermined DC voltage value required by the auxiliary equipment 30 or the like, the stabilization corrected by the DC / DC stabilizing power supply circuit 50 is performed. DC voltage can be supplied to the auxiliary device 30 and the like. In this case, the DC / DC stabilized power supply circuit 50
A power loss corresponding to the conversion efficiency is generated, but it is an effective means for ensuring the rated voltage of the auxiliary equipment 30 and the like.

In the above embodiment, the fuel cell power generation system 46 in the normal operation is configured to supply the electric power from the fuel cell 12 to the auxiliary equipment 30 and the like via the DC / DC stabilized power supply circuit 50. The switching circuit 44 may be reconfigured so that the system power supply 36 appropriately supplies electric power to the auxiliary machines 30, 31, 32 of the fuel cell power generation system 46 during normal operation.

That is, the main control section 48 is
When a state where the electrochemical reaction of the fuel cell 12 is temporarily lowered due to interruption of the supply of the fuel gas 19 or the oxidant gas 14 is detected, or when the output voltage of the fuel cell 12 is abnormally lowered due to overload, If detected, fuel cell 1
Auxiliary equipment 30, 31, 3 until the electrochemical reaction of 2 is restored
The switching circuit 44 can be reconfigured so that the power for the power supply 2 is supplied from the system power supply 36.

Since the switch 5, the diode 6 and the diode 7 which complement or replace the switching circuit 44 can use the same members as those in the above-mentioned embodiment, the description thereof will be omitted.

As described above, in the fuel cell power generation system, before the power supply from the fuel cell is started,
Auxiliary equipment power supply mechanism is reconfigured from the stage where the fuel cell power generation system is started by supplying the auxiliary power for operating the fuel cell from the commercial power system power supply, and the power is continuously output from the fuel cell. However, it is possible to disconnect the auxiliary power source from the power of the system power source and reconnect or switch to the output terminal side of the fuel cell.

Therefore, the auxiliary machine can provide stable power from the power source released from the power loss caused by the conversion efficiency of the DC booster circuit or the DC AC inverter connected to the system power source and the power loss caused by the voltage drop on the wiring. Can be supplied, and the power generation efficiency of the entire fuel cell power generation system can be improved.

Under the control of the main controller section,
The output voltage of the fuel cell during normal operation is monitored, and when the electrochemical reaction of the fuel cell is reduced under low or high load of the fuel cell, the auxiliary power source is supplied from the fuel cell side to the external power source. It is possible to provide a highly reliable fuel cell power generation system, which can be reconfigured so as to be temporarily switched to.

[0064]

As described above, according to the present invention, the main power system that supplies the power of the auxiliary machine from the system power supply at the time of start-up and outputs the power from the fuel cell to the system power supply during the normal operation of the fuel cell, Since the power for the auxiliary machine is supplied from the output terminal of the fuel cell, the power supply efficiency for the auxiliary machine is improved, and the power generation efficiency of the entire fuel cell power generation system can be improved.

Further, as compared with the system in which the power of the auxiliary machine is supplied from the output side of the grid interconnection inverter, as in the present invention,
By supplying power for auxiliary equipment from the output terminal of the fuel cell,
Since the output capacity of the DC / DC converter or the grid interconnection inverter can be configured in a small scale, the system can be downsized and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a fuel cell power generation system according to a first embodiment.

FIG. 2 is a schematic block diagram of a fuel cell power generation system according to a second embodiment.

FIG. 3 is a schematic block diagram of a fuel cell power generation system according to a third embodiment.

FIG. 4 is a schematic block diagram of a conventional fuel cell power generation system.

[Explanation of symbols]

12 Fuel cell 14 Oxidizer gas 16 Raw fuel 18 reformer 19 Fuel gas 20 DC / DC converter 22 DC / AC inverter 24 Stabilized power supply circuit 26 DC / DC converter 27 Dual power supply circuit 28 converter 29 Dual power supply circuit 30 Auxiliary equipment 31 Auxiliary equipment 32 Auxiliary equipment 33 Dual power supply circuit 36 system power supply 38 load 39 Fuel cell power generation system 40 Fuel cell power generation system 41 Conductor channel at A-side node 42 Main control section 43 B-side node conduction channel 44 Switching circuit 45 switching circuit 46 Fuel cell power generation system 48 Main control section 50 Stabilized power supply circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naohide Haga             1-6-34 Konan, Minato-ku, Tokyo Ebara Ballard             Within the corporation (72) Inventor Manabu Watanabe             1-6-34 Konan, Minato-ku, Tokyo Ebara Ballard             Within the corporation (72) Inventor Shoji Aoyama             1-6-34 Konan, Minato-ku, Tokyo Ebara Ballard             Within the corporation (72) Inventor Kazufumi Tateishi             1-6-34 Konan, Minato-ku, Tokyo Ebara Ballard             Within the corporation F-term (reference) 5H026 AA06                 5H027 AA06 BA01 DD01 MM26

Claims (3)

[Claims] 1. A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas; a DC / DC converter that transforms a DC voltage output from the fuel cell into a predetermined DC voltage; and the DC / DC converter. DC connected to the output side of the DC converter and converting the DC voltage transformed by the DC / DC converter into an AC voltage in order to connect to the system power supply.
/ AC inverter; an auxiliary machine power terminal for supplying electric power to an auxiliary machine; and a switching circuit for switching the auxiliary machine power terminal between the output side of the fuel cell and the output side of the DC / AC inverter. A fuel cell power generation system. 2. The fuel cell power generation system according to claim 1, further comprising an AC / DC stabilized power supply circuit between the output side of the DC / AC inverter and the switching circuit. 3. The fuel cell power generation system according to claim 1, further comprising a DC / DC stabilized power supply circuit between the output side of the fuel cell and the switching circuit.