Electrical transmission or interconnection systems – Plural supply circuits or sources – Connecting or disconnecting
Reexamination Certificate
2002-11-08
2004-10-05
Nguyen, Matthew V. (Department: 2838)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Connecting or disconnecting
C363S034000
Reexamination Certificate
active
06800963
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power controller that performs electric power generation by using DC power generation means, for example, a fuel cell, or the like.
2. Related Art of the Invention
Heretofore, a system shown in
FIG. 7
is known as a fuel cell power generation system (for example, refer to Japanese Patent Laid-Open No. 6-325774). In
FIG. 7
, a fuel cell
41
makes hydrogen, supplied by hydrogen supply means
42
, and oxygen in air, which is supplied by air supply means
43
, react in a main body of the fuel cell to generate DC power, which is converted into AC power by a power converter
44
and is outputted. A controller
45
can perform control so as to variably output electric power by electrical discharge from a charge and discharge apparatus
46
or charge to the charge and discharge apparatus
46
even if the generated power of the main body
41
of the fuel cell is fixed, by controlling the charge and discharge apparatus
46
and power converter
44
.
Nevertheless, though it is necessary in such a fuel cell power generation system to match an output voltage of the main body
41
of the fuel cell to charge and discharge voltages of the charge and discharge apparatus
46
, the charge and discharge apparatus
46
does not have means of controlling charge and discharge. Hence, it is difficult to control the charge and discharge of the charge and discharge apparatus
46
in high accuracy by compensating the difference between the output of the main body
41
of the fuel cell and ratings of power storage means such as a secondary cell in the charge and discharge apparatus
46
.
The following system is conceivable for canceling such a fault.
FIG. 8
shows a configuration of a fuel cell power generation system according to a second conventional example. In
FIG. 8
, a fuel cell
51
is a main body of a fuel cell to generate DC power by reacting hydrogen with oxygen in air. A DC/DC converter
52
boosts a voltage of DC power of the fuel cell
51
. A power converter
53
(inverter) converts the DC power, boosted by the DC/DC converter
52
, into AC power to output the AC power to an electric power load
55
. A controller
54
is the means of detecting a load current of the electric power load
55
by a load current detector
56
and controlling a two-way DC/DC converter
57
, the DC/DC converter
52
, and the power converter
53
.
The controller
54
stores electric power in a storage battery
58
through the two-way DC/DC converter
57
when a value of an output current from the main body
51
of the fuel cell according to the load current of electric power load
55
exceeds a load current value. When a value of the output current from the main body
51
of the fuel cell is insufficient for the load current value, the controller
54
supplies the electric power of the storage battery
58
to the electric power load
55
through the two-way DC/DC converter
57
.
The fuel cell power generation system according to the above-mentioned second conventional example (
FIG. 8
) has a configuration in which the power converter
53
is connected to the two-way DC/DC converter
57
for the charge and discharge control of the storage battery
58
coupled with an output of the DC/DC converter
52
that boosts DC power to a voltage necessary for converting DC power into AC power.
This system is made not only to control an output of the main body
51
of the fuel cell by the DC/DC converter
52
, but also to raise charge and discharge efficiencies of the storage battery
58
by controlling the two-way DC/DC converter
57
. Accordingly, charge from the fuel cell
51
to the storage battery
58
is performed through two voltage control means of the DC/DC converter
52
and two-way DC/DC converter
57
.
Nevertheless, since there is large difference between charge and discharge voltages of the storage battery
58
and an output voltage boosted by the DC/DC converter
52
(in general, the output voltage boosted by the DC/DC converter
52
is higher), it is necessary to increase the difference between step-up voltages and step-down voltages of the two-way DC/DC converter
57
according to the above difference. Hence, it is difficult to raise power conversion efficiency.
Moreover, there are issues that operating economy is low since total power conversion efficiency which is a product of a power conversion efficiency of the two-way DC/DC converter
57
and charge and discharge efficiencies of the storage battery
58
becomes low, in addition, cost also becomes high since a price of the two-way DC/DC converter
57
itself is also high.
SUMMARY OF THE INVENTION
In consideration of the above-mentioned issues, the present invention provides a fuel cell power controller, which quickly corresponds to a change of electric power demand, highly effectively generates electric energy required, and is highly economical and reliable, a power generation system using it, or the like.
One aspect of the present invention is a power controller comprising:
power storage means of storing DC power outputted from DC power generation means that generates DC power;
power conversion means of including at least a DC/DC converter that converts a voltage when receiving a DC input;
charge and discharge means of discharging electric power from the power storage means to the power conversion means and of charging DC power from the DC power generation means in the power storage means, the charge and discharge means being provided among the DC power generation means, the power storage means and the power conversion means;
detection means of detecting electric energy of an external power load to which power from at least the power conversion means is supplied; and
control means of controlling operation of the charge and discharge means on the basis of the detected electric energy,
wherein the charge and discharge means has a DC/DC conversion function, converts an output voltage of the DC power generation means into a charge voltage of the power storage means, and converts a discharge voltage of the power storage means into an output voltage of the DC power generation means.
Another aspect of the present invention is the power controller, according to the 1st invention.
wherein the control means performs control of making the charge and discharge means perform the charge operation when the external power load is low, and making the charge and discharge means perform the discharge operation when the external power load is high.
Still another aspect of the present invention is the power controller, according to the 1st invention,
wherein the amount of converted voltage between an output of the DC power generation means and an input of the power storage means is smaller than the amount of converted voltage between an output of the DC power generation means and an input of the DC/DC converter of the power conversion means.
Yet still another aspect of the present invention is the power controller, according to the 1st invention, wherein the charge and discharge means comprises:
charge side conversion means of converting an output voltage of the DC power generation means into a charge voltage of the power storage means; and
discharge side conversion means of converting a discharge voltage of the power storage means into an output voltage of the DC power generation means.
Still yet another aspect of the present invention is the power controller, according to the 1st invention, wherein the charge and discharge means comprises:
common conversion means of performing a charge side conversion operation in which an output voltage of the DC power generation means is converted into the charge voltage of the power storage means or a discharge side conversion operation in which a discharge voltage of the power storage means is converted into an output voltage of the DC power generation means;
a first control switch of performing control so that an input side of the common conversion means is connected to an output side of the DC power generation means or an output side of the po
Koike Kiichi
Miyauchi Shinji
Ozeki Masataka
Ueda Tetsuya
Zimbo Hiroyuki
Matsushita Electric - Industrial Co., Ltd.
Nguyen Matthew V.
RatnerPrestia
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