Electricity: battery or capacitor charging or discharging – Wind – solar – thermal – or fuel-cell source
Reexamination Certificate
2001-12-28
2002-08-06
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Wind, solar, thermal, or fuel-cell source
Reexamination Certificate
active
06429621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solar power charging system, and more particularly to a solar power charging system for charging a power generated from a solar battery into an electric double layer capacitor at a high efficiency.
2. Description of the Related Art
Advanced power systems integrate the solar power charging system which includes the solar battery and the electric double layer capacitor, so that a power is generated during the daytime and the generated power is consumed in the night in order to respond to environmental and energy requirements. This solar system is, for example, disclosed in Japanese laid-open patent publication No. 10-66281. It is important for the solar power charging system to increase the efficiency of supplying the generated power to the capacitor.
FIG. 1A
is a block diagram illustrative of a power system including a conventional solar power charging system.
FIG. 1B
is a block diagram illustrative of the conventional solar power charging system shown in FIG.
1
A. This conventional power system is also disclosed in Japanese laid-open patent publication No. 9-292851. A conventional solar power charging system
70
includes a solar battery
71
, a rectifier
72
such as a diode, a first DC-DC converter
73
, and an electric double layer capacitor
74
. The conventional solar power charging system
70
is connected to a second DC-DC converter
75
. The second DC-DC converter
75
is connected to an indicator
76
. The solar power charging system
70
stores a power. The second DC-DC converter
75
receives the power from the solar power charging system
70
and converts the voltage of the power. The power with the converted voltage is supplied to the indicator
76
for indicating the converted voltage level of the power.
With reference to
FIG. 1B
, the power voltage is supplied from the solar battery
71
through the rectifier
72
to the first DC-DC converter
73
. The power voltage generated by the solar battery
71
varies depending on sunshine conditions. The first DC-DC converter
73
converts the variable power voltage into a predetermined constant voltage level. The power with the predetermined constant voltage level is then supplied from the first DC-DC converter
73
to the electric double layer capacitor
74
, so that the electric double layer capacitor
74
is charged at the predetermined constant voltage level.
Charging the capacitor at the constant voltage level means that about a half of the generated power from the solar battery can theoretically be charged to the capacitor. This means that as long as the capacitor is charged at the constant voltage level, the efficiency of charging the capacitor is low.
The solar battery has a maximum power condition based on a variable generated power voltage level. The maximum power condition depends on a relationship between voltage and current from the solar battery. The method of charging the capacitor at the predetermined constant voltage level is incapable of satisfying the maximum power condition.
In the above circumstances, the development of a novel solar power charging system free from the above problems is desirable.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a novel solar power charging system free from the above problems.
It is a further object of the present invention to provide a novel solar power charging system capable of charging a capacitor under the maximum power condition.
The present invention provides a solar power charging system comprising: a voltage converter for converting a voltage level of an original voltage generated by a solar battery into generate a charging voltage and for charging a capacitor by the charging voltage; and a duty ratio control circuit electrically coupled to the voltage converter for supplying a driving clock to the voltage converter for allowing the voltage converter to operate based on the driving clock, wherein the duty ratio control circuit adjusts a duty ratio of the driving clock based on a maximum charge power which depends on the original voltage generated by the solar battery.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.
REFERENCES:
patent: 4434398 (1984-02-01), Higuchi
patent: 5493155 (1996-02-01), Okamoto et al.
patent: 0 628 901 (1994-12-01), None
patent: 9-292851 (1997-11-01), None
patent: 10-66281 (1998-03-01), None
patent: 2 2771096 (1998-04-01), None
NEC Corporation
Tso Edward H.
Young & Thompson
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