JP2002110210A - Hybrid fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid fuel cell system capable of supplying power stably and preventing reduction of service life of a storage battery. SOLUTION: This hybrid fuel cell system has a storage battery device provided with the storage battery 122 and an electric double layer capacitor (EDLC) 126. When power consumption of an external load 18 increases and the voltage outputted by a DC/DC converter 102 is reduced, electric discharge is made from the storage battery or EDLC. At this time, the EDLC discharges power corresponding to instantaneous power consumption by limiting the discharge current of the storage battery to prevent reduction of service life of the storage battery and output power corresponding to the changes of power consumption of the external load while operating a fuel cell power generating device 12 stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system in which reformed gas from a reformer is introduced into a fuel cell to convert DC power generated to AC power and supply the AC power to an external load. The present invention relates to a hybrid fuel cell system capable of supplying power stored in a power storage means such as a battery to an external load when generated power is lower than power consumption of an external load.

[0002]

2. Description of the Related Art Fuel cells such as a phosphoric acid type, a molten carbonate type, and a solid electrolyte type (solid oxide type, solid polymer type) use natural gas, methanol, etc. as a fuel gas and modify the fuel gas. The power is generated by reacting the hydrogen produced in the air with the oxygen in the air. At this time, hydrogen is generated from a fuel such as natural gas or methanol using a reformer or the like.

[0003] The power generated by such a fuel cell power generation device is generally supplied to a load operated by a commercial power supply (system power supply), such as a home electric appliance, via a system interconnection inverter or the like. (External load) can be used for operation of this external load.

In a fuel cell power generator, generated power is controlled by adjusting a supply amount of fuel gas.
For this reason, if the generated power is to be increased rapidly, for example, the supply of the fuel gas to the fuel cell cannot be made in time, and the output voltage will decrease due to a lack of hydrogen gas in the fuel cell.

[0005] For this reason, a hybrid fuel cell system in which a storage battery such as a battery is provided as an auxiliary power source in a fuel cell power generator is generally used. In this hybrid fuel cell system, when the power generated by the fuel cell is insufficient, the power stored in the storage battery is released to compensate for the shortage of the generated power, and the power corresponding to the power consumption of the external load is reduced. Can be output.

[0006]

However, some external loads require a large starting current, such as a load having a large rush component and a large motor. When such an external load is connected, the storage battery needs to output a large current in a short period of time, which increases the load on the storage battery and significantly reduces the life of the storage battery. In order to prevent such a reduction in the life of the storage battery,
A storage battery having a large capacity is required, and this storage battery leads to an increase in the size of the hybrid fuel cell system.

[0007] The present invention has been made in view of the above facts, and proposes a hybrid fuel cell system capable of preventing a decrease in the life of a storage battery without increasing the size of the system and enabling stable power supply to an external load. The purpose is to do.

[0008]

According to the present invention, there is provided a fuel cell power generation section for generating electric power in accordance with a supply amount of fuel gas, and a DC power generated by the fuel cell power generation section. Power conversion means for converting into AC power to be supplied to an external load; provided between the fuel cell power generation unit and the power conversion means for limiting an input current of the power conversion unit according to an output current of the fuel cell power generation unit Limiting means, first power storage means for storing power in a storage battery, second power storage means for storing power in an electric double layer capacitor, and the fuel cell power generation A first discharging unit for supplying the power generated by the fuel cell power generation unit together with the power generated by the fuel cell power generation unit to the power conversion unit in accordance with a change in the power generated by the unit and the power consumption of the external load; The power A second discharging unit that supplies the power conversion unit together with the power generated by the fuel cell power generation unit prior to the first power storage unit in accordance with a change in the power generated by the fuel cell power generation unit and the power consumption of the external load. And characterized in that:

According to the present invention, the electric power generated by the fuel cell power generation section is input to the electric power conversion means via the restriction means.
Thereby, when the power consumption of the external load increases, the insufficient power can be discharged from the first and second power storage means and supplied to the power conversion means.

At this time, the electric power discharged from the first power storage means is limited, and the electric double layer capacitor is provided in the second power storage means. The power according to the change in the power consumption of the external load can be discharged while preventing the first power storage unit from discharging a large amount of power instantaneously.

[0011] This makes it possible to prevent the life of the storage battery used for the first power storage unit from being shortened, in addition to the stable power generation of the fuel cell power generation unit.

[0012] The invention according to claim 2 is characterized in that the first charging means for charging the first power storage means with the electric power generated by the fuel cell power generation section, and the first charging means for charging the first power storage means with the electric power generated by the fuel cell power generation section. A second charging means for charging a first power storage means, and a second charging means for charging the first power storage means;
And charging control means for operating the charging means.

According to the present invention, when the generated power of the fuel cell power generation unit has a surplus, the first and second power storage means are charged. At this time, charging to the second power storage means is performed with priority. As a result, power can always be discharged in accordance with the increase in power consumption of the external load.

According to a third aspect of the present invention, the first and the second
The charging means can be supplied with electric power from the fuel cell power generation section together with the limiting means, and the first and second power storage means can be supplied to the power converting means together with the electric power restricted by the limiting means. It is characterized by being capable of discharging.

According to this invention, the first means is provided in parallel with the limiting means.
And second power storage means. Thus, not only the charging and discharging of the first power storage means but also the charging and discharging of the second power storage means can be performed efficiently and accurately.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a hybrid fuel cell system 10 applied to the present embodiment. This fuel cell power generation system 10 includes a fuel cell power generation device 12, an inverter device 14 using an inverter for system interconnection, and a storage battery device 16.

The inverter device 14 mainly converts the power generated by the fuel cell power generation device 12 into AC power having a predetermined voltage. The AC power output from the inverter device 14 is supplied to an external load 18 operable by a system power supply (commercial power supply). As the external load, general home appliances such as a television, a refrigerator, a washing machine, and an air conditioner (air conditioner) can be applied.
The external load 18 can be used not only for home electric appliances but also for electric appliances that can be operated by a commercial power supply.

FIG. 2 shows a schematic configuration of a fuel cell power generator 12 using a polymer electrolyte fuel cell as an example. The fuel cell power generation device is not limited to the solid polymer type, and various conventionally known configurations such as a phosphate type can be used.

The fuel cell power generator 12 includes a reformer 30, a C
An O transformer 32, a CO remover 34, and a fuel cell 36 are provided. Raw fuel (raw fuel gas) such as natural gas or methanol is supplied to the reformer 30 via the desulfurizer 40 by operating the pump 38. This fuel gas is supplied to the desulfurizer 4
0, the sulfur content is removed and the reformer 3
0 is supplied.

The reformer 30 is provided with a reformer burner 42, and a part of the fuel gas passing through the desulfurizer 40 can be supplied to the reformer burner 42. Further, air for combustion of the raw fuel gas is supplied to the reformer burner 42 by the operation of the pump 44. Thereby, the reformer burner 42 burns the raw fuel gas, heats the catalyst container of the reformer 30, and raises the temperature of the reforming catalyst in the catalyst container to the reaction temperature.

The fuel cell power generator 12 is provided with a water tank 46. When the pump 48 operates, water in the water tank 46 is sent to the heat exchanger 50 and passes through the heat exchanger 50. At this time, the exhaust gas is heated by the heat of the exhaust gas heated by the reformer burner 42 and introduced into the reformer 30 as steam together with the raw fuel gas.

In the reformer 30, steam supplied together with the raw fuel gas is mixed, and the reforming reaction (endothermic reaction) is performed by the reforming catalyst heated to the reforming reaction temperature by the reformer burner 42. Occurs. Thereby, a reformed gas rich in hydrogen is generated from the raw fuel gas.

The raw fuel gas (reformed gas) that has passed through the reformer 30 is sent to a fuel cell 36 through a CO converter 32 and a CO remover 34. In the CO shift converter 32, a carbon monoxide shift reaction (exothermic reaction) occurs in which carbon monoxide generated together with hydrogen by the reforming reaction reacts with water (steam). As a result, hydrogen is generated together with carbon dioxide in the reformed gas.

The CO remover 34 is supplied with the reformed gas that has passed through the CO shift converter 32, thereby causing a selective oxidation reaction at a low temperature. This further reduces the concentration of carbon monoxide in the reformed gas. That is, the reformed gas passes through the CO shift converter 32 and the CO remover 34, whereby the concentration of carbon monoxide is reduced in two stages of high temperature and low temperature, and is reformed and converted into a hydrogen-rich gas to be converted into a fuel cell. 36.

Between the reformer 30 and the CO converter 32,
Between the CO transformer 32 and the CO remover 34 and the CO remover 3
4 and the fuel cell 36, heat exchangers 52A, 52B,
52C are provided. In each of the heat exchangers 52A to 52C, water in the water tank 46 is circulated by pumps 54A, 54B, 54C, so that the reformed gas is cooled when passing through the heat exchangers 52A to 52C.

Further, valves 56A and 56B are provided on the reformed gas exhaust side of the heat exchanger 52C. In the fuel cell power generator 12, the reformer 30, the CO converter 32, C
Until the temperature of each catalyst in the O remover 34 is stabilized, the valve 56A is closed and the valve 56B is open. As a result, the reformed gas is sent from the CO remover 34 to the process gas burner (PG burner) 58,
After being burned with the air sent to the G burner 58,
It passes through the heat exchanger 62 and is discharged as exhaust gas.

Further, the fuel cell power generation device 12 is provided with a hot water storage tank 64 for utilizing exhaust heat.
The water circulated between the hot water storage tank 64 and the heat exchanger 62 by 6 is heated by the PG burner 58.

The fuel cell power generator 12 includes a CO transformer 32
And when the temperature of each catalyst in the CO remover 34 is stable,
The valve 56A is opened to send the reformed gas to the fuel cell 36. The fuel cell 36 has an anode 70 and a cathode 72. The fuel cell 36 is supplied with air by a pump 68. Note that the reformed gas is the anode 70
, And air is supplied to the cathode 72.

In the fuel cell 36, an electrode reaction occurs in which hydrogen in the reformed gas supplied to the anode 70 is used as fuel and oxygen in the air supplied to the cathode 72 is used as an oxidizing agent. An electromotive force is generated in between. The fuel cell 36 can take out electric power by this electromotive force. A cooling unit 74 is provided in the fuel cell 36, and is cooled by circulating water in the water tank 46 by a pump 76.

On the exhaust gas output side from the anode 70 of the fuel cell 36, valves 78A and 78B are provided.
In the fuel cell power generator 12, the valve 78A is closed and the valve 78B is opened until the temperature of the fuel cell 36 is stabilized, and exhaust gas containing unreacted hydrogen gas is supplied to the PG burner 58.

In the fuel cell power generator 12, when the fuel cell 36 reaches a stable and operable state, the valve 78B is closed and the valve 78A is opened. Thus, the unreacted gas that has passed through the anode 70 is supplied to the reformer burner 42. In the reformer burner 42, the fuel cell 36 reaches a stable operation state and the anode 70
Is supplied to supply the unreacted gas discharged from the reactor, the unreacted gas is mainly burned.
When the temperature of the catalyst within 0 cannot be maintained at the reforming reaction temperature, the raw fuel gas that has passed through the desulfurizer 40 is supplied to the reformer burner 42.

As described above, the fuel cell power generator 12 applied to the present embodiment has a hot water supply function utilizing waste heat, and is circulated through the heat exchangers 52A to 52C and the cooling unit 74 of the fuel cell 36. The water in the water tank 46 thus heated is sent to the heat exchanger 82 by the pump 80A. Water (hot water) in the hot water storage tank 64 is circulated to the heat exchanger 82 by the pump 80B, whereby heat exchange is performed and the water in the water tank 46 is cooled. At the same time, the water in the hot water storage tank 64 is heated.

The exhaust gas discharged from the reformer 30 and having passed through the heat exchanger 50 further passes through a heat exchanger 84.
The water in the hot water storage tank 64 is heated by being circulated in the heat exchanger 84 by the pump 86. Also,
The exhaust gas discharged from the cathode 72 of the fuel cell 36 is
It passes through a heat exchanger 88. In the heat exchanger 88, the water in the hot water storage tank 64 is circulated by the pump 90 to be heated.

As described above, in the fuel cell power generator 12,
Exhaust heat recovery is performed by heating the water in the hot water storage tank 64 using the heat of the exhaust gas or the like, and the hot water heated by the recovered heat is stored in the hot water storage tank 64 for hot water supply.

On the other hand, as shown in FIG. 1, the hybrid fuel cell system 10 is provided with a controller 100 having a microcomputer (not shown). The controller 100 is connected to various operation means such as various pumps and valves provided in the fuel cell power generation device 12 and various sensors such as a temperature sensor and a pressure sensor via an input / output interface (not shown) ( Both are not shown).

Thus, the controller 100 detects the temperatures and pressures of the respective units such as the reformer 30, the CO shift converter 32, the CO remover 34, and the fuel cell 36, and operates the various pumps based on the detection results. By performing control such as opening and closing of a valve, the fuel cell power generator 1
2 is controlled.

For example, when increasing the power generated by the fuel cell 36, the controller 100 gradually increases the amount of the raw fuel gas supplied to the reformer 30. As a result, in the fuel cell power generator 12, the amount of the reformed gas supplied to the fuel cell 36 increases, and the amount of air supplied increases in accordance with the increase in the reformed gas. The power generation reaction is promoted, and the generated power gradually increases. Further, in the fuel cell power generation device 12, the amount of the reformed gas supplied to the fuel cell 36 is reduced by gradually decreasing the amount of the raw fuel gas supplied to the reformer 30.
The power generated by the power is reduced.

On the other hand, the inverter device 14 includes a DC / DC converter 102 provided as limiting means and a DC / AC inverter 104 provided as power converting means. The DC / DC converter 102
A booster circuit having a conventionally known general configuration using a DC chopper, a transformer, a rectifier, and the like can be used, and converts DC power input from the fuel cell power generator 12 into DC power of a predetermined voltage.

The DC / AC inverter 104 has a D
DC power input from the C / DC converter 102 is
The power is converted into AC power of a predetermined voltage used for operation of the external load 18. In addition, as the DC / AC inverter 104, a general configuration that converts DC power into AC power by switching a bridge-connected switching element at a predetermined timing can be applied, and a detailed description is omitted in the present embodiment. I do. In the present embodiment, the external load 1
Although the DC / AC inverter 104 is used to obtain AC power corresponding to the electrical device because the electrical device operated by AC power is used as 8, power is supplied to an external load operated by DC power. Is supplied, a DC / DC converter that outputs DC power for operating the external load may be used instead of the DC / AC inverter 104.

The DC / DC converter 102 is connected to the controller 100. In addition, the fuel cell power generator 1
Between the fuel cell power generator 1 and the controller 100
A current sensor 106 and voltage sensor 108 for detecting the generated current I _FC and the generator voltage V _FC is taken out from the 2 is provided between the DC / DC converter 102 and DC / AC inverter 104, the output of the DC / DC converter 102 a current sensor 110 and voltage sensor 112 detects the voltage V _d to be input to the current I _d and DC / AC inverter 104 is provided.

On the external load 18 side (output side) of the DC / AC inverter 104, a current sensor 114 for detecting an _AC current I _AC to be output and a voltage sensor 116 for detecting an _AC voltage VAC are provided. .

The current sensors 106, 110, 114 and the voltage sensors 108, 112, 116
Connected to 0. The controller 100 controls the AC current I _AC detected by the current sensor 114 and the voltage sensor 1
External load 18 from an AC voltage V _AC for detecting the 16
Of the fuel cell power generation device 12 is controlled based on the power consumption.

[0043] At this time, the controller 100, the target value I of the generated current I _FC based on the power consumption of the external load 18
Set the _FCO, the amount of the raw fuel gas as the power generation current I _FC becomes the target value I _FCO, set the air amount and the like, various pumps based on the amount and the air amount and the like of the raw fuel gas, a valve, etc. Control.

That is, as shown in FIG. 3, when the target value _IFCO increases, the controller 100
The supply of fuel gas is being increased in line with the increase in _FCO . Note that the controller 100 controls the supply amount of the fuel gas in accordance with the target value _IFCO within a range in which the fuel cell power generator 12 operates stably.
The target value _IFCO is corrected based on the catalyst temperature of the reformer 30 and the like.

The controller 100 has a DC / DC
DC / DC converter 102 so that the output power of converter 102 does not exceed the power generated by fuel cell power generator 12.
Control. That is, the controller 100, generated power I _FC based on the target value I _FCO for setting the limit value I _FR1 of the input current inputted to the DC / DC converter 102, DC / DC Input current limiter value of the inverter 102 controlling the current I _d so as not to exceed I _FR1. Further, the controller 100 varies the limiter value I _FR1 based on the output current of the fuel cell 36. This gives D
C / DC converter 102 outputs the limited current I _d in accordance with the output current I _FC of the fuel cell 36.

The controller 100 sets the limit value I _FR1 of the current I _d of the DC / DC converter 102 based on the output current I _FC of the fuel cell 36 detected by the current sensor 106, and
The current I _d is controlled so as not to exceed the limit value I _FR1. At this time, as shown in FIG.
00 is set so that the limiter value I _FR1 is increased stepwise in accordance with the supply amount of the raw fuel gas accompanying the increase in the target value I _FRO .

On the other hand, as shown in FIG.
The output side is a DC / DC converter 102 and a DC / AC
It is connected between the inverters 104, and stores the accumulated power together with the output power of the DC / DC
It can be supplied to the C / AC inverter 104. As a result, the DC / AC inverter 104 becomes the DC / DC
Power or DC / DC output from converter 102
The power output from the converter 102 and the storage battery device 16 can be converted into AC power to be supplied to the external load 18. The input side of the storage battery device 16 is connected to the output side of the fuel cell power generator 12 (fuel cell 36) together with the DC / DC converter 102, and the fuel cell power generator 1
2 can be charged by using the electric power generated by the electric power.

[0048] Between the fuel cell 36 and the storage battery device 16,
A current sensor 118 that detects a charging current I _BI input from the fuel cell power generation device 12 to the storage battery device 16 is provided;
Between the power storage device 16 and the DC / AC inverter, a current sensor 120 that detects a discharge current _IBO output from the storage battery device 16 is provided. Current sensors 118, 120
Are connected to the controller 100.

The storage battery device 16 provided in the hybrid fuel cell system 10 has a storage battery unit 124 using a storage battery 122 such as a battery serving as first power storage means.
And a second storage battery unit 1 using an electric double layer capacitor (EDLC: Electric Double Layer Capacitor, hereinafter referred to as “EDLC 126”) as a second power storage means.
28 are provided.

The EDLC 126 is a capacitor that uses an adsorption / desorption reaction of an ion adsorption layer (electric double layer) formed on the surface of activated carbon for charging and discharging of electric charge. For example, a pair of activated carbon electrodes (electrolyte solution) Is added), and is composed of conductive current collectors on both sides. Electrically, a large-capacitance capacitor with internal resistance and a small-capacitance capacitor are connected in parallel. It can be approximated, and has a general configuration capable of rapid charging and rapid discharging.

On the other hand, the storage battery section 124 is formed by the storage battery 122, the charging circuit 130 and the discharging circuit 132,
The storage battery unit 128 is formed by the EDLC 126, the charging circuit 134, and the discharging circuit 136. Storage battery unit 1
24 and 128 are connected in parallel, and the storage battery 22 and E
The power stored in the DLC 26 can be output (discharged) to the DC / AC inverter 104, and the storage battery 12 using the power generated by the fuel cell power generator 12.
2 and the EDLC 126 can be charged.

The charging circuit 1 of the storage battery units 124 and 128
Each of the discharge circuits 30, 134 and the discharge circuits 132, 136 is connected to the controller 100. This allows
For example, the controller 100 determines the remaining capacity of the storage battery 122 and the EDLC 126 from the terminal voltage of the storage battery 122 and the terminal voltage of the EDLC 126, and controls the charging circuits 130 and 134 when the remaining capacity decreases due to the discharge. And charging the EDLC 126. The controller 100 controls the discharge circuits 132 and 136 based on the output power of the DC / DC converter 102 and the power consumption of the external load 18 to
22 to the power stored in the EDLC 126 is discharged.

Here, the hybrid fuel cell system 1
0, the current I output from the DC / DC converter 102
_{Since the} limiter value I _FR1 is set for _d , the current I _d is limited when the current I _d is about to increase due to an increase in the power consumption of the external load 18, so that the DC / DC converter 102 output to the voltage V _d of decreases.

That is, as shown in FIG.
/ DC converter 102, until current input reaches the limiter value I _FR1, although the voltage V _d has a substantially constant voltage V _0, the current current input exceeds the limit value I _FR1 I _d There When attempts to flow, the limiter value I _FR1 is the voltage V _d decreases a drooping point.

On the other hand, the controller 100 has a DC / DC
Voltage V output from converter 102 ₀Discharge times
Output voltage V of path 132₁Is slightly lower and the discharge circuit
136 output voltage V_TwoIs the output voltage V of the discharge circuit 132₁
It is set to be slightly lower than (V₀> V₁> V
_Two). For example, the voltage V of the DC / DC converter 102₀To
200 V and the output of the discharge circuit 136 (the storage battery unit 128)
Force voltage V_TwoIs set to 190v, the discharge circuit 1
32 (storage battery unit 124)₁Is the voltage V₀And output
Voltage V_TwoIs set at about 195v, which is an intermediate point between the two.

Thus, the DC / DC converter 102
Output to the voltage V _d of starts discharge from the battery 122 by drop below the voltage V _1, the voltage V _d by drop below the voltage V _2, further discharge from EDLC126 is started.

The discharge circuit 132 includes a storage battery 122.
An output current limiter for limiting the discharge current I _OB of the storage battery 122 to a limiter value I _RB set for the storage battery 122 is provided. Note that the discharge circuit 136 is provided with an output current limiter that limits the discharge current I _OC of the EDLC 126 to a limiter value I _RC set for the EDLC 126.

As a result, as shown in FIGS. _4B and 4C, the voltages _Vb and V of the discharge circuits 132 and 136 are changed.
_c is the voltage V ₁ , V ₂ until the discharge currents I _OB , I _OC reach the limit values I _RB , I _RC , but the discharge currents I _OB , I _OC become the limit values I _RB , I _RC Is reached, the limiter values I _RB and I _RC are reduced as drooping points.

Each of the discharge circuits 132 and 136 determines the remaining capacity based on, for example, the terminal voltage of the storage battery 122 and the EDLC 126 in order to prevent overdischarge of the storage battery 122 and the EDLC 126.
When the specified values set for each of the EDLC 22 and the EDLC 126 are reached, the discharge is stopped. Further, when the storage battery device 16 stops discharging, the controller 100
The operation of the hybrid fuel cell system 10 is stopped to protect the fuel cell power generator 12 together with the storage battery 122 and the EDLC 126.

On the other hand, the controller 100
2 and the EDLC 126 are charged, limiters I _FR3 and I _FR2 of respective charging currents I _IB and I _IC (input currents to the charging circuits 130 and 134) are set. Thereby, each of the charging circuits 130 and 134 supplies the charging current I
_The storage battery 122 and the EDLC 126 are charged while _IB and I _IC are limited to limiter values I _FR3 and I _FR2 .

As shown in FIGS. 5B and 5D, the controller 100 includes a storage battery 122 and an EDL.
When the charging of C126 is started, the limiter value I _FR3 ,
I _FR2 is gradually increased from 0 (zero) to set values I _FRB and I _FRC .

As a result, as shown in FIGS. 5A and 5C, the charging voltages V _IB and V _IC (output voltages of the charging circuits 130 and 134) input to the storage batteries 122 and 126, respectively.
Gradually rises to the set values V _BS and V _CS . That is, the controller 100 performs a so-called soft start of charging. FIG.
FIGS. 5A and 5B show the charging voltage V _IB and the charging current I _IB for the storage battery 122, and FIGS.
(D) shows the charging voltage V _IC and the charging current I _IC for the EDLC 126.

Further, the controller 100 controls the storage battery 12
2, the EDLC 126 is charged with priority, and even when the storage battery 122 is discharging,
When it is determined that charging of DLC 126 is necessary, ED
The LC 126 is charged.

Here, the hybrid fuel cell system 1
The charging / discharging flow of the storage battery device 16 at 0 will be described with reference to FIGS.

The controller 100 provided in the hybrid fuel cell system 10 sets the target value I _FRO of the generated current based on the power consumption of the external load 18 calculated from the _AC current I _AC and the AC voltage I _{AC and the} like. The operation of the fuel cell power generator 12 is controlled based on the target value _IFRO . This allows the hybrid fuel cell system 10 to generate and output power according to the power consumption of the external load 18.

The controller 100 sets a limiter value I _{FR1 of the} current input to the DC / DC converter 102 based on the supply amount of the raw fuel gas, and limits the current I _d .

As a result, in the hybrid fuel cell system 10, the power consumption of the external load 18 rapidly increases,
If insufficient power generated in the voltage V _d output from the DC / DC converter 102 is lowered, the storage battery device 16
Then, a state is started in which discharge from the battery is started. Note that the controller 100 controls the fuel cell power generation device 12 so as to increase the generated power in accordance with the increase in the power consumption of the external load 18.

FIG. 6 shows the flow of the discharging process in the storage battery device 16. In the first step 200 of this flowchart, the voltage V _d of the DC / DC converter 102 is shown.
(The voltage input to the DC / AC inverter 104)
It is confirmed whether or not lower than voltages V ₁ to start discharge of the discharge circuit 132.

That is, when the capacity (power consumption) of the external load 18 sharply increases, the DC / DC converter 102
Output current _Id increases. Thereby, DC / D
When the input current of C converter 102 reaches limiter value I _FR1 , voltage V output from DC / DC converter 102
_d drops sharply.

[0070] In this case, when the voltage V _d becomes the voltage V ₁ or less,
When an affirmative determination is made in step 200, the process proceeds to step 202, where the discharge circuit 132 starts discharging from the storage battery 122. Accordingly, the power of the battery 122 is supplied to the DC / AC inverter 104, if the slight lack of generated power amount of the fuel cell 36 to the power consumption of the external load 18, is suppressed decrease in the voltage V _d, the external load The fuel cell 18 is operated by the power generated by the fuel cell 36 and the power discharged from the storage battery 122.

In the next step 204, the voltage V _d
But it is checked whether the lower than the voltage V ₂ to start discharge of the electric power accumulated in the EDLC126.

The power consumption of the external load 18 increases rapidly,
Battery 122 can not be suppressed decrease of the voltage V _d be discharged, when the voltage V _d falls below the voltage V _2, Step 20
When the determination in step 4 is affirmative, the process proceeds to step 206. As a result, the discharge from the EDLC 126 is started.

On the other hand, the controller 100 and the discharge circuit 13
2, when discharging from the storage battery 122, the storage battery 1
The discharge current is limited based on the capacity of the capacitor 22 and the overdischarge is prevented. Further, the controller 100 and the discharge circuit 136 prevent the EDLC 126 from being over-discharged when discharging from the EDLC 126.

FIG. 7A shows an example of the limitation of the discharge current of the storage battery 122. In this flowchart, the discharge circuit 132 starts discharging (step 202 in FIG. 6).
And is terminated by stopping the discharge.

The limitation of the discharge current of the storage battery 122 is as follows.
In the first step 220, it is checked whether or not the discharge current I _OB output from the discharge circuit 132 has reached a preset limiter value I _RB , and the discharge current I _OB is set to a limiter value I _RB.
If it has not reached (Yes in step 220), the process proceeds to step 222 to perform normal discharge control.

On the other hand, when the power consumption of the external load 18 is larger than the generated power and the discharge current I _OB output from the discharge circuit 132 reaches the limiter value I _RB , step 22
If the determination is 0, the process proceeds to step 224 to limit the discharge current I _OB . As a result, the discharge circuit 132 outputs the discharge current I _OB limited to the limiter value I _RB . For this reason, the voltage _Vd further decreases even though the battery 122 is discharged. This discharge limitation occurs when the discharge current I _OB falls below the limiter value I _{RB and}
It is released by a negative determination of 0.

In step 226, the storage battery 122
It is checked whether the remaining capacity of the battery has decreased to a predetermined value set in advance to protect the storage battery 122 from overdischarge, and when the remaining capacity reaches the specified value (a positive determination in step 226), step 228 is performed. Then, the discharge from the storage battery 122 is stopped, and the operation of the hybrid fuel cell system 10 is stopped.

As shown in FIG. 7B, the EDLC
During discharge from the EDLC 126, the remaining capacity of the EDLC 126 becomes
Pre-set to protect EDLC 126 from over-discharge
Check whether the value has decreased to the specified value (step 2).
30) When the remaining capacity reaches the specified value (step 23).
0, affirmative determination), and proceed to step 232, where EDLC
126 and the hybrid fuel
The operation of the battery system 10 is stopped. What
In the discharge circuit 136, the limiter value I _RCBased on
And discharge current I_OCMay be performed.

As a result, for example, as shown in FIG. 8A, the power consumption of the external load 18 sharply increases at time t ₁ , and the output of the DC / AC inverter 104 is increased with the increase in the power consumption. When the power increases, as shown in FIG. 8 (B), the electric power generated by the fuel cell 36 from the time t ₁ is increased gradually.

At this time, if the power generated by the power generator 36 is insufficient for the power consumption, the current I _d output from the DC / DC converter 102 is limited by the limiter value I _FR1 and the voltage V _d decreases. Occurs.

As a result, as shown in FIG. 8E, the discharging of the electric power stored in the storage battery 122 from the discharging circuit 132 is started, and the DC / DC converter 102 and the discharging circuit 1
32 output from the DC / AC inverter 104
Is input to

Here, if the power inputted to the DC / AC inverter 104 is still insufficient for the discharge circuit 132 to limit the discharge current I _OB with the limiter value I _RB , FIG. As shown, the discharge circuit 136 is
The discharge of the electric power stored in 6 is started.

As described above, the EDLC 126 is connected to the storage battery 1.
Since the rapid discharge is possible as compared with 22, when the power consumption of the external load 18 changes abruptly, it is possible to discharge the power according to the change of the power consumption of the external load 18. At this time, the discharge current I _OB of the storage battery 122 is limited by the limiter value I _RB . As a result, as shown in FIG. 8C, electric power is discharged from the storage battery device 16 in accordance with the shortage of the output power of the fuel cell 36.

At this time, as shown in FIG.
The discharge power of the DLC 126 changes according to a rapid change in power consumption (output power of the DC / AC inverter), and FIG.
As shown in (E), the storage battery 122 does not discharge power whose discharge current I _OB exceeds the limit value I _RB .

Therefore, it is possible to prevent the life of the storage battery 122 from being shortened due to the flow of a large discharge current from the storage battery 122, and the storage battery 122 can be used for a long time.

Further, as shown in FIGS. 8A to 8C, the storage battery device 16
The output power of the fuel cell 36 relative to the output power of the fuel cell 36 is discharged using the EDLC 126 in addition to the storage battery 122, so that the output of the fuel cell 36 can be stabilized and the stable operation of the fuel cell power generator 12 Is possible. That is, the storage battery device 16 is connected to the external load 1
8, when the power consumption changes rapidly, the power corresponding to this change can be reliably discharged.
The output power of the converter 102 and the fuel cell 36 does not suddenly change.

On the other hand, in the flowchart of FIG.
When discharging is performed using C126, in step 208,
Voltage V _d, and checks whether increased to voltage V _2, when the voltage V _d is a positive determination result is obtained in step 208 exceeds the voltage V _2, the process proceeds to step 210. In this step 210, the discharge circuit 136 stops discharging, and
The discharge from the LC 126 is completed (time t ₂ shown in FIG. 8D).

[0088] In step 212, the voltage V _d to confirm whether increased to voltages V _1, the voltage V _d is voltages V ₁
Is exceeded in step 212,
Move to step 214. In this step 214,
When the discharge circuit 132 stops discharging, the storage battery 1
The discharge from 22 is terminated (time t ₄ shown in FIG. 8E).

That is, as shown in FIGS. 8A to 8E, as the output power of the fuel cell 36 increases, the power consumption of the external load 18 and the power generated by the fuel cell 36 (DC / DC) are increased. By reducing the difference in the power output from converter 102, storage battery device 16 (storage battery 122
When the power discharged from the EDLC 126 gradually decreases and the power consumption of the external load 18 can be covered by the power generated by the fuel cell 36, the discharge from the storage battery device 16 is stopped.

On the other hand, the hybrid fuel cell system 10
Then, the storage battery 122 of the storage battery device 16 and E
When the capacity of the DLC 126 decreases, the storage battery 122 and the EDLC 126 are charged by the power generated by the fuel cell 36.

FIG. 9 shows the storage battery 122 and the EDLC 12
6 shows the outline of the charging process. In this flowchart, in the first step 240, for example, the EDLC 126
EDLC from the remaining capacity calculated based on the terminal voltage of
It is determined whether charging to 126 is necessary.

Here, if it is determined that the remaining capacity of the EDLC 126 has decreased due to the discharge, and that the EDLC 126 needs to be charged (Yes at step 240),
The process proceeds to step 242, where it is determined whether or not the EDLC 126 is discharging.
If not, the process moves to step 244 and the EDLC1
The charging process for the battery 26 is started.

The remaining capacity of the EDLC 126 may be sufficient (negative determination in step 240),
When the charging to 6 is completed, the process proceeds to step 246,
For example, the storage battery 1 calculated from the terminal voltage or the like of the storage battery 122
It is determined from the remaining capacity of the storage battery 22 whether or not the storage battery 122 needs to be charged. In step 248, the storage battery 12
2 and whether or not the discharge of the EDLC 126 is stopped.

Here, it is determined that the remaining capacity of storage battery 122 is low and charging is necessary (Yes at step 246).
At the same time, if the discharge of the storage battery 122 and the EDLC 126 is stopped (Yes at Step 248), Step 2
The process proceeds to step S50, where the charging process for the storage battery 122 is performed.

That is, in the storage battery device 16, the storage battery 1
While charging the EDLC 126 in preference to 22;
If the EDLC 126 needs to be charged, the storage battery 122
The battery may be charged even during discharging from the battery.

For example, FIGS. 8A, 8B and 8
(E), the in between times t ₂ of time t _3, D
The power input to the C / AC converter 104 has a surplus. At this time, as shown in FIG.
While continuing the discharge of 2, the EDLC 126 is charged.

Thus, in the storage battery device 16, E
A state where discharge from the DLC 126 is possible and an external load 1
8 when the power consumption of the external load 1
8, the EDLC 126 can be discharged in accordance with an increase in power consumption. Therefore, even when the power consumption of the external load 18 temporarily increases, the operation of the fuel cell 36 and the fuel cell power generator 12 can be stabilized.

On the other hand, FIGS. 8A, 8B and 8
As shown in (E), charging of the storage battery 122 is started after the power consumption of the external load 18 can be covered by the fuel cell 36 (time t ₄ ).

At this time, the power generated by the fuel cell 36 is increased by increasing the power consumption of the external load 18 (output power of the DC / AC inverter 104), and the surplus is generated in the generated power to charge the storage battery 122. It is (time t ₄ ~ time t _8). In other words, the power consumption of the external load 16 (the output of the DC / AC inverter 104) that changes at each of the times t ₄ , t ₅ , t ₆ , t ₇ , and t ₈ and the surplus power generated according to the generated power are used as the storage battery 122. Charge efficiently.

The controller 100 controls the storage battery device 16
When to charge the (battery 122 or EDLC126), sets a limiter value I _BFR of the charging current I _BI. When charging the EDLC 126, the limiter value I _BFR is applied to the charging circuit 130 by applying the limiter value I _FR2 to the charging current I _IC input to the charging circuit 134, and when charging the storage battery 122. The limiter value I _{FR 3} of the charging current I _IB is applied.

Next, the limiter value I _BFR and the DC / D
From the limiter value I _FR1 of the current I _d of the C converter 102,
It sets a target value I _FCO generated current I _FC, so that the current I _FC becomes the target value I _{FC O,} controls the operation of the fuel cell power plant 12.

That is, the controller 100 sets the target value I set based on the power consumption of the external load 18.
_{The FCO} is _stored in the storage battery 122 of the storage battery device 16 or the EDLC.
126 is corrected based on the limiter value _IBFR when charging 126, and the generated power is controlled so as to obtain the corrected target value _IFCO .

As a result, the generated current I _FC of the fuel cell 36
Becomes surplus and is input to the storage battery device 16 as the charging current I _BI , and the storage battery 122 or the EDLC 126 can be charged.

At this time, the controller 100 gradually increases the limiter values I _FR2 , I _FR3 and sets the set values I _FRC , I _FR3.
To reach the _Fed , so that DC / DC
The battery 122 and EDLC126 can be charged without changing the current I _d to the output of the converter 102.

On the other hand, the controller 100
The EDLC 126 is charged even when the storage battery 122 is discharging, giving priority to the charging of the EDLC 126. For this purpose, for example, the controller 100
In a state that can not increase the target value I _FCO of _FC, correcting the limit value I _FR1 to limit the current I _d of the DC / DC converter 102.

That is, the controller 100 controls the DC /
Limiter value I of input current of DC converter 102
_FR1 is set to I _FR1 = I _FCO −I _{FRC so} that the current I _d output from the DC / DC converter 102 is limited based on the set limit value I _FR1 . At this time, DC
If the power output from DC / DC converter 102 is insufficient, voltage _Vd decreases, so that discharge circuit 132 of storage battery 122 discharges the power of storage battery 122, and external load 18
Power according to the power consumption of the DC / AC inverter 104
Is input to

As a result, as shown in FIG. 8D and FIG.
6 can be charged.

As described above, the controller 100
When the LC 126 needs to be charged, the EDLC 126 is charged while the power of the storage battery 122 is being discharged. Thereby, the EDLC 126 is always kept in a dischargeable state.

Therefore, in the storage battery device 16, even if the power consumption of the external load 18 increases instantaneously, the external load 1 is maintained while the fuel cell power generation device 12 is operated in a stable state.
8 according to the power consumption of the DC / AC inverter 10
4 (external load 18).

In the storage battery device 16, the storage battery 122
Is provided in addition to the EDLC 126, the storage battery 12
2 can be prevented from changing instantaneously, and thereby a reduction in the life of the storage battery 122 can be suppressed.

Further, the hybrid fuel cell system 10
Since the storage battery device 16 is provided in parallel with the DC / DC converter 102 provided as the limiting means, not only the charging and discharging of the storage battery device 16 but also the charging of the EDLC 126 can be performed efficiently and reliably.

Note that the present embodiment described above is an example of the present invention and does not limit the configuration of the present invention. For example, the present invention is not limited to the fuel cell power generation device 12 shown in FIG.

[0113]

As described above, according to the present invention, since the second power storage means using the electric double layer capacitor is provided in addition to the first power storage means using the storage battery, the external load of the external load can be reduced. Even if the power consumption increases instantaneously, it is possible to obtain an excellent effect that the fuel cell power generation unit can be stabilized and the life of the storage battery can be prevented from being shortened.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram illustrating an example of a fuel cell power generation device to which the present invention is applied.

FIG. 3 shows a target value I of a generated current with respect to a supply amount of a raw fuel gas.
Limiter value I of input current of _FCO and DC / DC converter
It is a diagram showing the outline of _FR1 .

4A is a diagram schematically illustrating a voltage with respect to an input current of a DC / DC converter, FIG. 4B is a diagram schematically illustrating a discharge voltage with respect to a discharge current of a discharge circuit provided with a storage battery, FIG. (C) is a diagram schematically showing a discharge voltage with respect to a discharge current of a discharge circuit provided with the EDLC.

5A is a diagram schematically showing a change in a charging voltage of a storage battery, FIG. 5B is a diagram schematically showing a change in a charging current input to a charging circuit provided with the storage battery, and FIG. ) Is ED
FIG. 3D is a diagram schematically showing a change in the charging voltage of the LC, and FIG.
FIG. 3 is a diagram schematically illustrating a change in a charging current input to a charging circuit provided with an LC.

FIG. 6 is a flowchart showing an outline of discharging from the storage battery device.

FIG. 7A is a flowchart showing an outline of discharge protection for a storage battery, and FIG. 7B is a flowchart showing an outline of discharge protection for an EDLC.

FIG. 8A shows DC / A according to power consumption of an external load.
A diagram illustrating an example of the output power of the C converter, (B) is a diagram illustrating an example of the output power of the fuel cell according to the power consumption of the external load, and (C) is a diagram illustrating a change in the external load and a change in the generated power. (D) is a diagram showing an example of charging and discharging of the EDLC according to a change in external load and a change in generated power, and (E) is a diagram showing an example of charging and discharging of the storage battery device. FIG. 4 is a diagram illustrating an example of charging and discharging of a storage battery according to a change in generated power.

FIG. 9 is a flowchart showing an example of charging of the storage battery device.

[Explanation of symbols]

Reference Signs List 10 hybrid fuel cell system 12 fuel cell power generation device (fuel cell power generation unit) 14 inverter device 16 storage battery device 18 external load 36 fuel cell (fuel cell power generation unit) 100 controller (first and second discharge means, charge control means, Limiting means) 102 DC / DC converter (Limiting means) 104 DC / AC inverter (Power conversion means) 122 Storage battery 124 Storage battery unit (First power storage means) 126 EDLC (Electric double layer capacitor, Second power storage means) 128 Storage battery Unit (second power storage means) 130 Charging circuit (first power storage means) 132 Discharge circuit (first power storage means) 134 Charging circuit (second power storage means) 136 Discharge circuit (second power storage means)

 ──────────────────────────────────────────────────の Continuing on the front page (72) Koji Shindo, Inventor Sanyo Electric Co., Ltd. 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka (72) Inventor Kazuhiro Tajima 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. F term (reference) 5G003 AA05 BA01 DA15 DA18 5G065 DA04 DA07 EA02 HA16 LA01 LA02 NA01 5H027 AA06 BA01 BA09 BA16 BA17 CC06 DD03 DD09 MM26

Claims (3)

[Claims] 1. A fuel cell power generation unit that generates electric power according to a supply amount of fuel gas, and a power conversion unit that converts DC power generated by the fuel cell power generation unit into AC power supplied to an external load. Limiting means provided between the fuel cell power generation section and the power conversion means for limiting an input current of the power conversion section in accordance with an output current of the fuel cell power generation section; first power storage means for storing power in a storage battery Second power storage means for storing power in an electric double layer capacitor; and power stored by the first power storage means according to fluctuations in power generated by the fuel cell power generation unit and power consumption of the external load. A first discharging unit that supplies the power generated by the fuel cell power generation unit together with the power generated by the fuel cell power generation unit; and a power stored in the second power storage unit. Load power consumption A second discharging means for supplying to the power conversion means together with the power generated by the fuel cell power generation section prior to the first power storage means in response to a change in power. . 2. A first charging unit for charging the first power storage unit with electric power generated by the fuel cell power generation unit; and a first charging unit configured to charge the first power storage unit with electric power generated by the fuel cell power generation unit.
2. The hybrid according to claim 1, further comprising: a second charging unit that charges the power storage unit; and a charging control unit that activates the second charging unit prior to the first charging unit. 3. Fuel cell system. 3. The power supply from the fuel cell power generation unit can be supplied to the first and second charging means together with the restriction means, and the first and second power storage means are provided with the restriction means. 3. The power conversion device according to claim 2, wherein the power is discharged to said power conversion means together with the power limited by said power conversion means.
3. The hybrid fuel cell system according to item 1.