Power control apparatus for solar power generation system

• US 5,923,158 A
• Filed: 08/28/1997
• Issued: 07/13/1999
• Est. Priority Date: 08/30/1996
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takehara, Nobuyoshi, Kurokami, Seiji, Fukae, Kimitoshi
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/919,445
• Time in Patent Office: 684 Days
• Field of Search: 323/299, 323/303, 323/906, 363/78, 363/79
• US Class Current: 323/299
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

In a power control apparatus of a solar power generation system for converting power generated by a solar panel and supplying the converted power to a load, the output voltage and output current of the solar panel are sensed, and, under ordinary conditions, MPPT control is performed so that the solar cells will operate at a maximum output point. If the output power of the solar panel exceeds a predetermined power, a power conversion unit is controlled so as to raise the output voltage of the solar panel, thereby limiting the output power of the solar panel. As a result, excessive power is prevented from being output by the power control apparatus.

Claims

1. A power control apparatus for supplying a load with power output by a solar cell, comprising:

converting means for converting output power of the solar cell to power conforming to the load;

sensing means for sensing output voltage and output current of the solar cell;

setting means for setting operating voltage of the solar cell based upon the output voltage and output current sensed; and

control means for controlling operation of said converting means in such a manner that the output voltage of the solar cell becomes the set operating voltage;

wherein said setting means raises the operating voltage by a predetermined amount of voltage in a case where the product of the output voltage and output current sensed is greater than a predetermined value.

2. The apparatus according to claim 1, wherein said setting means sets the operation voltage so as to obtain maximum output power from the solar cell in a case where the product of the output voltage and output current sensed is equal to or less than the predetermined value.

3. The apparatus according to claim 1, wherein said control means controls the output voltage of the solar cell by controlling ON/OFF duty of gate pulses applied to switching devices of said converting means.

4. A power control method for supplying a load with power output by a solar cell, comprising the steps of:

sensing output voltage and output current of the solar cell;

setting operating voltage of the solar cell based upon the output voltage and output current sensed; and

controlling operation of a conversion unit, which converts output power of the solar cell to power conforming to the load, in such a manner that the output voltage of the solar cell becomes the set operating voltage,

wherein the step of setting the operating voltage raises the operating voltage by a predetermined amount of voltage in a case where the product of the output voltage and output current sensed is greater than a predetermined value.

5. A power control apparatus for supplying a load with power output by a solar cell, comprising:

converting means for converting output power of the solar cell to power conforming to the load;

sensing means for sensing output voltage and output current of the solar cell;

designating means for designating an operating condition of the solar cell based upon the output voltage and output current sensed; and

control means for controlling operation of said converting means based upon a designation made by said designating means,

wherein, in a case where the product of the output voltage and output current sensed is equal to or less than a predetermined value, said designating means designates the operating voltage of the solar cell and said control means controls operation of said converting means in such a manner that the output voltage of the solar cell attains the operating voltage that has been designated, and

wherein in a case where the product of the output voltage and output current sensed exceeds the predetermined value, said designating means designates to raise the operating voltage of the solar cell and instructs said control means to suppress power.

6. The apparatus according to claim 5, wherein said designating means designates the operating voltage so as to obtain maximum output power from the solar cell in a case where the product of the output voltage and output current sensed is equal to or less than the predetermined value.

7. The apparatus according to claim 5, wherein said control means controls the output voltage of the solar cell by controlling ON/OFF duty of gate pulses applied to switching devices of said converting means.

8. The apparatus according to claim 5, wherein, in a case where the product of the output voltage and output current sensed becomes equal to or less than the predetermined value after suppression of power has been designated, said designating means designates instructs said control means to cancel suppression of power.

9. A power control method for supplying a load with power output by a solar cell, comprising the steps of:

sensing output voltage and output current of the solar cell;

designating an operating condition of the solar cell based upon the output voltage and output current sensed; and

controlling operation of a conversion unit, which converts output power of the solar cell to power conforming to the load, based upon a designation made;

wherein, in a case where the product of the output voltage and output current sensed is equal to or less than a predetermined value, said designating step designates the operating voltage of the solar cell and said control step controls operation of said conversion unit in such a manner that the output voltage of the solar cell attains the operating voltage that has been designated; and

in a case where the product of the output voltage and output current sensed exceeds the predetermined value, said designating step designates to raise the operating voltage of the solar cell and designates suppression of power.

10. A power control apparatus for supplying a load with power output by a solar cell, comprising:

converting means for converting output power of the solar cell to power conforming to the load;

first sensing means for sensing output power of said converting means;

second sensing means for sensing output voltage and output current of the solar cell;

setting means for setting operating voltage of the solar cell based upon the sensed output voltage and output current of the solar cell; and

control means for controlling the output voltage of the solar cell by controlling operation of said converting means based upon the set operating voltage and sensed output power of said converting means,

wherein, in a case where the value of the sensed output power of said converting means is greater than a predetermined value, said control means controls the operation of said converting means based on a control voltage obtained by raising the operating voltage by a predetermined amount of voltage.

11. The apparatus according to claim 10, wherein said setting means sets the operating voltage, in such manner that maximum output power is obtained from the solar cell, based upon sensed output voltage and output current of the solar cell.

12. The apparatus according to claim 10, wherein, in a case where the value of the sensed output power of said converting means becomes equal to or less than the predetermined value after start of control based upon the control voltage, said control means controls the operation of said converting means based upon a lower ed control voltage.

13. The apparatus according to claim 10, wherein said control means control the output voltage of the solar cell by controlling ON/OFF duty of gate pulses applied to switching devices of said converting means.

14. A power control method for supplying a load with power output by a solar cell, comprising the steps of:

sensing output power of a conversion unit which converts output power of the solar cell to power conforming to a load;

sensing output voltage and output current of the solar cell;

setting operating voltage of the solar cell based upon the sensed output voltage and output current of the solar cell; and

controlling the output voltage of the solar cell by controlling operation for said conversion unit based upon the set operating voltage and sensed output power of said conversion unit,

wherein, in a case where the value of the sensed output power of the conversion unit is greater than a predetermined value, the operation of the conversion unit is controlled based on a control voltage obtained by raising the operating voltage by a predetermined amount of voltage.