Solar power generation system, control device used for solar power generation system, and control method and program for same

• US 8,908,404 B2
• Filed: 08/26/2011
• Issued: 12/09/2014
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: School Judicial Person Ikutokugakuen
• Original Assignee: School Judicial Person Ikutokugakuen
• Inventors: Itako, Kazutaka
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): AHMED, YUSEF A
• Application Number:
  US13/819,613
• Publication Number:
  US 20130155739A1
• Time in Patent Office: 1,201 Days
• Field of Search: 363 37- 41, 363 79- 81, 363 95- 98, 363131-132, 323222-225, 323271-275, 323282-285, 323299-300, 323/906
• US Class Current: 363/95
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: G05F 3/08 wherein the variable is dc
• CPC Class Codes: G05F 5/00 Systems for regulating electric variables by detecting deviations in the electric input to the system and thereby controlling a device within the system to obtain a regulated output
• CPC Class Codes: H02M 7/44 by static converters
• CPC Class Codes: H02S 10/00 PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 323/906 Solar cell systems

Abstract

In a light power generation system, a control device, a control method, and a program, efficient power can be supplied. The maximum power detection unit operates a MOSFET in a power converter circuit and open-circuits both ends of a solar cell panel in the maximum power detection mode. After that, the maximum power detection unit short-circuits both ends of the solar cell panel, detects a maximum power by monitoring the output power of the solar cell panel during a period from the open state to the short-circuited state, and defines the voltage of the solar cell panel as an optimal voltage when detecting the maximum power. In a tracking operation mode, the control unit performs PWM control with respect to the MOSFET by defining the optimal voltage to be a reference signal. Operations are repeated between the maximum power detection mode and the tracking operation mode.

Claims

1. A light power generation system comprising:

a light power generation unit for generating power in response to incident light;

a voltage detecting means for detecting an output voltage of the light power generation unit;

a current detecting means for detecting an output current of the light power generation unit, or a power detecting means for detecting an output power of the light power generation unit;

a power converting means including a switching element for making an open state and close state between the output terminals of the light power generation unit, converting the voltage between the output terminals of the light power generation unit, and outputting a power corresponding to said voltage; and

a controlling means for performing a control operation of a maximum power detection mode for detecting the maximum power of the light power generation unit at that time and a control operation of a tracking operation mode for carrying out a tracking control so that the maximum power detected in the maximum power detecting mode can be output from the light power generation unit,

wherein the controlling means, in the maximum power detection mode,

makes the switching element in the power converting means operate ON state and OFF state to result in a first voltage state between the output terminals of the light power generation unit,

makes the switching element operate ON state and OFF state to change the state of the voltage between the output terminals of the light power generation, from the first voltage state to a second voltage state different to the first voltage state, and during a transition state moving from the first voltage state to the second voltage state, detects a time at which the power of the product of the voltage which was detected by the voltage detecting means and the current which was detected by the current detecting means or the power which was detected by the power detecting means becomes the maximum, and defines a voltage which was detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage, and

wherein, the controlling means, in the tracking operation mode,

makes the switching element operate ON state and OFF state so that a difference between a reference voltage which is the optimal output voltage and the voltage which was detected by the voltage detecting means becomes “

0”

or almost “

0”

.

2. The light power generation system as set forth in claim 1, wherein the power converting means includes a DC-DC converter which includes the switching element which is provided so as to open/close the output terminals of the light power generation unit.

3. The light power generation system as set forth in claim 1, wherein the power converting means includes an inverter which includes the switching element which was provided so as to open/close the output terminals of the light power generation unit.

4. The light power generation system as set forth in claim 1, wherein:

the power converting means includes

a DC-DC converter provided between the output terminals of the light power generation unit constant, and

an inverter which includes the switching element which is provided in an output side of the DC-DC converter, and

the controlling means has

a first controlling means for controlling the DC-DC converter, so that the voltage between the output terminals of the light power generation unit is maintained constant, and

a second controlling means for controlling the inverter in response to a state of a load.

5. The light power generation system as set forth in claim 1, which the controlling means corrects an operation point of a hill-climbing method by using the optimal output voltage detected in the maximum power detection mode.

6. The light power generation system as set forth in claim 1, wherein the light power generation unit comprises a solar cell generation unit for generating power in response to an incident light.

7. The light power generation system as set forth in claim 1, wherein

the first voltage state is an open state of the output terminals of the light power generation unit, and the second voltage state is a short state of the output terminal, or

the first voltage state is a short state of the output terminal, and the second voltage state is an open state of the output terminal, or

the first voltage state is a first state of a first voltage of the output terminal, and the second voltage state is a second state of a second voltage different to the first voltage of the output terminal.

8. A control device which is applied to a light power generation control system which comprises a light power generation unit which generates power in response to incident light, a voltage detecting means for detecting an output voltage of the light power generation unit, a current detecting means for detecting an output current of the light power generation unit or a power detecting means for detecting an output power of the light power generation unit, and a power converting means which includes a switching element for making an open state and close state between the output terminals of the light power generation unit, converts the voltage between the output terminals of the light power generation unit, and outputs a power corresponding to said voltage, wherein

the control device is a control device which performs a control operation in a maximum power detection mode for detecting the maximum power of the light power generation unit at that time and a control operation in a tracking operation mode for carrying out a tracking control so that the maximum power detected in the maximum power detecting mode can be output from the light power generation unit, and

the control device,

in the maximum power detection mode,

makes the switching element in the power converting means operate ON and OFF state to result in to the first voltage state between the output terminals of the light power generation unit and

makes the switching element operate ON state and OFF state to change the state of the voltage between the output terminals of the light power generation, from the first voltage state to a second voltage state different to the first voltage state, and during a transition state moving from the first voltage state to the second voltage state, detects a time at which the power of the product of the voltage which was detected by the voltage detecting means and the current which was detected by the current detecting means or the power which was detected by the power detecting means becomes the maximum, and defines a voltage which was detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage, and

in the tracking operation mode,

defines the optimal output voltage as a reference voltage and makes the switching element operate ON and OFF state so that the difference between the reference voltage and the voltage detected by the voltage detecting means becomes “

0”

or almost “

0”

.

9. The control device as set forth in claim 8, wherein:

the control device comprises

a maximum power detecting means for operating in the maximum power detection mode, monitoring the power of the product of the voltage which was detected by the voltage detecting means and the current which was detected by the current detecting means or the power which was detected by the power detecting means, detecting the maximum power, and detecting the optimal voltage corresponding to the detected maximum power,

a holding means for holding the detected optimal voltage,

a reference signal generating means, when operating in the maximum power detection mode, generating a first reference signal for making the switching element in the power converting means operate ON state and OFF state during a transition time from the first voltage state to the second voltage state between the output terminals of the light power generation unit, and a second reference signal for making the switching element ON state and OFF state so that the output terminal of the light power generation unit which falls by a predetermined rate to the second voltage state from the first voltage state during the transition time,

a first controlled operating means for generating a control signal in accordance with a difference between the first and second reference signals which are output from the reference signal generating means and the voltage which was detected by the voltage detecting means in the maximum power detection mode,

a second controlled operating means for generating a control signal in accordance with a difference between the optimal voltage which is held in the holding means and the voltage which was detected by the voltage detecting means in the tracking operation mode,

a signal selecting means for selecting and outputting the output signal of the first controlled operating means in the maximum power detection mode and selecting and outputting the output signal of the second controlled operating means in the tracking operation mode,

a control signal generating means for generating a control signal for controlling the drive of the switching element of the power converting means in accordance with the output signal of the signal selecting means, and

a mode controlling means for switching between the maximum power detection mode and the tracking operation mode.

10. The control device as set forth in claim 9, wherein:

the power converting means includes a DC-DC converter which includes the switching element which is provided so as to open/close the output terminals of the light power generation unit, and

the control device controls drive of the switching element in the DC-DC converter so that the voltage between the output terminal of the light generation unit is maintained constant.

11. The control device as set forth in claim 10, wherein:

the power converting means includes a DC-DC converter which is controlled so as to maintain the voltage between the output terminals of the light power generation unit constant, and

an inverter which includes the switching element which is provided in the output side of the DC-DC converter and is controlled in accordance with a load, and

the controlling means performs

first control processing of controlling the DC-DC converter, and

second control processing of controlling the inverter.

12. The control device as set forth in claim 8, wherein the control signal generating means generates a control signal for controlling by PWM the switching element of the power converting means in accordance with the output signal of the signal selecting means.

13. The control device as set forth in claim 8, which corrects an operation point of a hill-climbing method by using the optimal output voltage detected in the maximum power detection mode.

14. The control device as set forth in claim 8, wherein the light power generation unit comprises a solar cell generation unit for generating power in response to an incident light.

15. The control device as set forth in claim 8, wherein

the first voltage state is an open state of the output terminals of the light power generation unit, and the second voltage state is a short state of the output terminal, or

the first voltage state is a short state of the output terminal, and the second voltage state is an open state of the output terminal, or

the first voltage state is a first state of a first voltage of the output terminal, and the second voltage state is a second state of a second voltage different to the first voltage of the output terminal.

16. A control method which is applied to a light power generation system which has a light power generation unit which generates power in response to incident light, a voltage detecting means for detecting a terminal voltage of the light power generation unit, a current detecting means for detecting an output current of the light power generation unit or a power detecting means for detecting an output power of the light power generation unit, and a power converting means including a switching element for making an open state and close state between the output terminals of the light power generation unit and converting the voltage between the output terminals of the light power generation unit and outputting a power of the corresponding to said voltage, wherein

the control method performs a control operation in a maximum power detection mode for detecting the maximum power of the light power generation unit at that time and a control operation in a tracking operation mode for carrying out a tracking control so that the maximum power detected in the maximum power detecting mode can be output from the light power generation unit, controlling the switching element in the two modes, and comprises steps of,

in the maximum power detection mode,

making the switching element in the power converting means operate ON state and OFF state to result in a first voltage state between the output terminals of the light power generation unit,

making the switching element operate ON state and OFF state to change the state of the voltage between the output terminals of the voltage between the output terminals of the light power generation, from the first voltage state to a second voltage state different to the first voltage state, and during a transition state moving from the first voltage state to the second voltage state, detecting a time at which the power of the product of the voltage which was detected by the voltage detecting means and the current which was detected by the current detecting means or the power which was detected by the power detecting means becomes the maximum, and defining a voltage which was detected by the voltage detecting means at the time when detecting the maximum power as the optimal output voltage, and

in the tracking operation mode,

using the optimal output voltage as a reference voltage and making the switching element operate ON state and OFF state so that a difference between the reference voltage which is the optimal output voltage and the voltage which was detected by the voltage detecting means becomes “

0”

or almost “

0”

.

17. The control method as set forth in claim 16, which corrects an operation point of a hill-climbing method by using the optimal output voltage which was detected in the maximum power detection mode.

18. The control method as set forth in claim 16, wherein the light power generation unit comprises a solar cell generation unit for generating power in response to an incident light.

19. The control method as set forth in claim 16, wherein

the first voltage state is an open state of the output terminals of the light power generation unit, and the second voltage state is a short state of the output terminal, or

the first voltage state is a short state of the output terminal, and the second voltage state is an open state of the output terminal, or

the first voltage state is a first state of a first voltage of the output terminal, and the second voltage state is a second state of a second voltage different to the first voltage of the output terminal.