JPH0962386A - Control method for power converter for photovoltatic power generation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and surely perform the start and stop of the maximum power follow-up control of a solar battery. SOLUTION: This control method of a power converter which feeds the output power of the solar battery 1 to a load 3 via a power converter 2 and performs the maximum power follow-up control to adjust the operating point of the solar battery 1 so as to maximize the output power of the solar battery 1 is the control method for the power converter for photovoltatic power generation which starts the maximum power follow-up control when the output power of the solar battery 1 shows a value larger than a first preset value and stops such control when it shows a value less than a second preset value smaller than the first preset value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a power converter for photovoltaic power generation.

[0002]

2. Description of the Related Art Since the output power of a solar cell varies greatly depending on the operating point of the solar cell, in order to effectively use the generated power of the solar cell, the operating point that gives the maximum power of the solar cell is searched for and operated there. Maximum power tracking control that moves points must be performed. However, since the generated power of the solar cell is almost flat during low solar radiation, even if maximum power tracking control is performed in this state, it becomes rather inefficient. Therefore, normally, the maximum power follow-up control is stopped during solar radiation. In the past, the start / stop of the maximum power tracking control was determined by determining that the output voltage of the solar cell reached the set value.

[0003]

However, in the conventional method of determining the output voltage of the solar cell, the output voltage of the solar cell greatly changes depending on the temperature of the solar cell, etc. There were problems such as error and unstable operation. Therefore, the problem to be solved by the present invention is to stably and reliably start and stop the maximum power tracking control of the solar cell.

[0004]

In order to solve the above-mentioned problems, the present invention supplies the output power of a solar cell to a load through a power converter so that the output power of the solar cell is maximized. In a control method of a power converter that performs maximum power tracking control for adjusting an operating point of a solar cell, the maximum power tracking control is started when the output power of the solar cell becomes a first set value or more, and the first power tracking control is performed. Second less than the set value
The maximum power tracking control is stopped when the value becomes equal to or less than the set value of.

[0005]

By the above means, the maximum power point tracking control is started and stopped while measuring the generated power of the solar cell,
The generated power of the solar cell can be effectively used without being affected by conditions such as the temperature of the solar cell, and the maximum power tracking control can be started by setting the second set value smaller than the first set value. Repeated stoppage (hunting) can be prevented and stable control becomes possible.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, 1 is a solar cell, 2 is a power converter, 3 is a system power supply and load, 4 is a solar cell voltage detection circuit, 5 is a solar cell current detection circuit, 6 is a solar cell output power calculator, and 7 is maximum power. This is a follow-up control start / stop determination circuit. FIG. 2 is a flowchart showing the control procedure of the present invention. Next, the operation of the embodiment of the present invention will be described with reference to the flowchart of FIG. The output voltage V _S and the output current I _S of the solar cell 1 are detected by the solar cell voltage detection circuit 4 and the solar cell current detection circuit 5 of FIG. 1, and the output power P _S of the solar cell 1 is calculated by the solar cell output power calculator 6 Is calculated (step 110 in FIG. 2). The maximum power tracking control start / stop determination circuit 7 is capable of storing the start power represented by the first set value and the stop power represented by the second set value smaller than the first set value. The generated power P _S of the solar cell 1 calculated by the device 6 is compared with the start power and the stop power (step 120 in FIG. 2), and the generated power P
_{If S} is larger than the start power, the start signal of the maximum output point tracking control is sent to the power converter 2 (step 13 in FIG. 2).
0), if the generated power is smaller than the stop power (step 140 in FIG. 2), the stop signal for the maximum output point tracking control is sent to the power converter 2 (step 150 in FIG. 2).

The power converter 2 starts the maximum power tracking control.
When the start signal is received from the stop determination circuit 7, the maximum power point tracking control is continued until the stop signal is received. At this time, since the start power (first set value)> the stop power (second set value), the start / stop state is repeated even when the solar cell output power fluctuates near the start power and the stop power. , Does not cause so-called hunting. Therefore, stable operation is possible in terms of control.

[0008]

As described above, the present invention has the following effects. (1) The maximum power point tracking control of the solar cell can be started and stopped stably and reliably. (2) Hunting can be prevented when the generated power is low. (3) As described above, it is possible to stabilize the control circuit and improve the reliability.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the present invention.

[Explanation of symbols]

1 solar cell, 2 power conversion device, 3 system power supply and load, 4 solar cell voltage detection circuit, 5 solar cell current detection circuit, 6 solar cell output power calculator, 7 maximum power tracking control start / stop determination circuit

Claims (1)

[Claims] 1. A power for supplying maximum output power of a solar cell to a load via a power converter and performing maximum power tracking control for adjusting an operating point of the solar cell so that the output power of the solar cell becomes maximum. In the control method of the conversion device, the maximum power tracking control is started when the output power of the solar cell becomes equal to or higher than a first set value, and the second power smaller than the first set value is set.
The method for controlling a power conversion device for photovoltaic power generation, wherein the maximum power tracking control is stopped when the value becomes equal to or less than a set value of.