Batteries: thermoelectric and photoelectric – Applications – Circuits
Reexamination Certificate
2000-03-23
2001-09-18
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Applications
Circuits
C136S258000, C136S291000, C323S906000, C363S015000, C363S027000
Reexamination Certificate
active
06291764
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a photovoltaic power generation device, more particularly relates to a photovoltaic power generation device for protecting a power inverter from an overvoltage.
2. Description of Prior Art
A solar cell device for generating photovoltaic power, which is located outside, has been paid attention as a promising way for solving the global environmental problems. A photovoltaic power generation system, in which a solar cell device arranged on a roof or the like generates power and covers the power consumed during the daytime, has been developed.
In this system, power outputted from the solar cell device is a direct current. Therefore, the power is inverted from the direct current outputted from the solar cell device into an alternate current by a power inverter before use.
The above power inverter does not start immediately after obtaining power generated in the solar cell device, but starts after checking output from the solar cell device for a predetermined time. It is because that noise may be generated in the output power when the power inverter starts under an unstable condition of power generation by the solar cell device such as at dawn of day.
As described above, since a conventional power inverter does not start until the power generated in the solar cell device is stabilized for a predetermined time, an open voltage increases. Particularly, in an early morning of winter, an open voltage becomes large. As a result, a power inverter with a larger withstand voltage than an operating voltage is required, and it causes an increase in cost and a deterioration in operation efficiency at a normal operating voltage.
SUMMARY OF THE INVENTION
The present invention was made to solve the above described problems by presenting an increase in an open voltage and an overvoltage applied to a power inverter. In addition, the present invention was made to increase an optimum operating voltage of a power inverter and provide a photovoltaic power generation device capable of improving operation efficiency.
A photovoltaic power generation device according to this invention comprises a solar cell device, a power inverter for inverting output from the solar cell device into AC power, a current path circuit connected in parallel between the solar cell device and the power inverter, and a current detection circuit for detecting a current which feeds back to the solar cell device. The current path circuit is cut off when the current detected by the current detection circuit reaches beyond a predetermined current value.
The solar cell device in the photovoltaic power generation device comprises an amorphous silicon solar cell element.
In the above composition, when a current generated in the solar cell device does not reach a predetermined value, a little current flows through the current path circuit. Thus, the solar cell device does not have an open voltage even when the power inverter does not operate. An increase in a voltage is suppressed, and a withstand voltage can be ensured even when an optimum operating voltage is set high.
When an amorphous silicon solar cell element is used as a solar cell device, a fill factor (F.F.) is small. It sometimes causes a voltage beyond a maximum input voltage in an early morning of winter. In the present invention, an increase in voltage does not change much in comparison with a state when a power inverter is operating because a current flows through the current path circuit at the same time when power generation starts.
The current detection circuit in the photovoltaic power generation device detects a current on a basis of output from a blocking diode.
The circuit can be co-used since a current is detected by utilizing output of the blocking diode.
A photovoltaic power generation device according to this invention comprises a solar cell device, a power inverter for inverting output from the solar cell device into AC power, a current path circuit connected in parallel between the solar cell device and the power inverter, a power supply circuit provided between the current path circuit and the power inverter and controlled by output from the current path circuit, and a current detection circuit for detecting a current which feeds back to the solar cell device. The current path circuit is cut off when the current detected by the current detection circuit reaches beyond a predetermined current value.
The power inverter in the photovoltaic power generation device includes a main circuit and a control circuit, and driving power for the control circuit is applied from the solar cell device.
In the above composition, when a current generated in the solar cell device is less than a predetermined value, a little current flows through the current path circuit. Thus, the solar cell device does not have an open voltage even when the power inverter does not operate. An increase in a voltage is suppressed, and a withstand voltage can be ensured even when an optimum operating voltage is set high.
The current detection circuit in the photovoltaic power generation device detects a current on a basis of a blocking diode.
The power supply circuit in the photovoltaic power generation device switches a current dividing the current path circuit and a current from the solar cell device from one another and supplies either of them.
The power supply circuit in the photovoltaic power generation device is provided with means for turning on and off a current flowing between the solar cell device and the power inverter, and means for supplying a current supplied from the current path circuit to the power inverter.
The means for turning on and off a current in the photovoltaic power generation device is a thyristor or a self-hold type relay.
REFERENCES:
patent: 4333136 (1982-06-01), Baker
patent: 4375662 (1983-03-01), Baker
patent: 4390940 (1983-06-01), Corbefin et al.
patent: 5886890 (1999-03-01), Ishida et al.
patent: 6175512 (2001-01-01), Hagihara et al.
patent: 1039621-A2 (2000-09-01), None
patent: 61/55719-A (1986-03-01), None
patent: 8/98549-A (1996-04-01), None
Hagihara Ryuzo
Ishida Takeo
Kishi Hitoshi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Diamond Alan
Sanyo Electronics Co., Ltd.
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