JP3021244B2 - Power control device and power supply device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control device and a power supply device using the same, and more particularly, to a power control device capable of obtaining a maximum output from a power supply such as a solar cell and a power supply using the same. It concerns the device.

[0002]

2. Description of the Related Art In recent years, interest in the environment and energy, such as depletion of fossil fuels such as petroleum and coal, global warming, and radioactive contamination due to a nuclear accident, has been rapidly increasing. Under these circumstances, solar cells, wind power generation, thermoelectric power generation, and the like are expected from all over the world as renewable and inexhaustible clean energy sources.

In an apparatus using such a power supply,
2. Description of the Related Art A system is employed in which a power supply supplies power to a power supply system serving as a load or an independent load such as a secondary battery through power conversion means such as an inverter or a chopper. The solar cell, which is one of the power supplies, has a voltage-current characteristic and a voltage-power characteristic as shown in FIG. 2 as output characteristics of the solar cell with the amount of incident solar radiation as a parameter. Alternatively, the output greatly changes depending on the voltage, and the output becomes maximum at a certain operating point. (Here, the voltage value and the current value at the optimum operation point at which the output from the power supply becomes maximum are referred to as the optimum operation point voltage Vop and the optimum operation point current Iop.) The output from the solar cell is the amount of solar radiation. And the solar cell output tends to increase as the amount of solar radiation increases. Focusing on the optimal operating point at each solar radiation, the optimal operating point current Iop increases with an increase in the solar radiation, while the optimal operating point voltage Vop does not change much with the change in the solar radiation and is almost constant. .

[0004] In order to maximize the power supplied from a power supply having such characteristics, it is necessary to control the operation of the power conversion means to make the operating point an optimum operating point.

As one of the control methods for maximizing the output of the power supply, there is a method of controlling the output voltage of a solar cell or the like as a power supply at a constant voltage. This is the optimum operating point voltage Vo of the solar cell.
The fact that p becomes substantially constant with respect to changes in the amount of solar radiation is used. However, when controlling at a certain constant voltage, for example, when the temperature changes, the optimum operating point voltage Vop changes, and the power taken out sharply drops from the maximum power, so that another power can be effectively taken out from the solar cell. There is a problem that there is no. In addition, the output characteristics differ depending on the power supply used, and the voltage setting becomes a problem.If the power supply is used for many years, the output characteristics of the solar cell and the like will vary depending on the output characteristics of the power supply itself, the variation in the amount of solar radiation, and the degree of contamination. Since it is affected by various factors, it is very difficult to predict the set voltage.

As a method for overcoming such a problem,
There is a control method that always follows the optimum operating point. This is to change the voltage or current at the operating point in order to search for the optimal operating point of the solar cell, and to control it to be the optimal operating point based on information such as the voltage and current obtained there. is there. As an example of this control method, Japanese Unexamined Patent Publication (Kokai) No. Sho-59 (1995) discloses a method in which the operating point of a solar cell is changed, current and voltage are sampled at a plurality of operating points, and the voltage is adjusted to the voltage at the point where the power becomes maximum. 62-42213. Japanese Patent Publication No. 63-57807 discloses a method of controlling the operation point so that the current differential value of the power obtained by changing the operation point of the solar cell becomes zero. Further, Japanese Patent Application Laid-Open No. Sho 62-85312 discloses a method in which the operating point of a solar cell is changed from a certain operating point to another operating point, and the output powers of the two points are compared to determine the changing direction of the operating point voltage. And so on.

[0007]

However, conventionally, in the case where the optimum operating point is always followed, the operating point voltage or the operating point voltage for changing the operating point of the power supply in order to obtain information necessary for following the optimal operating point is conventionally known. No consideration has been given to the magnitude of the change in operating point current.

However, the amount of change in the operating point voltage or operating point current affects the output power taken from the power supply, and the steepness of the output power causes a large change in the operating point voltage or operating point current. It can be seen that the output power decreases. In addition, the voltage and current of the solar cell and the like also change greatly and are not stable.

This is an example of a conventional control method for obtaining maximum power, in which a current and a voltage are sampled at a plurality of operating points, and control is performed so that the voltage at the point where the power becomes maximum is obtained. It was considered that the solar cell temperature change was considered to be very slow, so the sampling interval was several tens of minutes or more, but the weather change was fast, and the solar cell temperature was strongly affected by sunlight. However, if the voltage is kept constant for a certain length of time or more, only the greatly reduced output power can be obtained from the maximum output beyond the optimum operating point. Therefore, it is desirable to always follow the optimum operating point so that the maximum output is obtained. At this time, as for the magnitude of the change of the operating point, it is considered that the smaller the magnitude, the higher the efficiency but the slower the response. On the other hand, the control circuit that controls the power conversion means requires high-precision components when the magnitude of the change in the operating point is reduced, so that an increase in cost is inevitable. Thus, it has been found that setting the magnitude of the change in the operating point is an important issue.

Also, an operating point is controlled so that a current differential value of electric power obtained by changing an operating point of a solar cell becomes zero, or an operating point of a solar cell is changed from one operating point to another operating point. The same applies to the case where the operating point voltage is changed by determining the changing direction of the operating point voltage by comparing the two powers. The setting of the magnitude of the changing of the operating point is also important.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a power control apparatus having a control for extracting a maximum output from a power supply and obtaining a maximum output with good tracking performance, and a power supply using the same. The purpose is to provide.

[0012]

The object of the present invention is to provide an output control means for detecting an operating point of input power, an optimum operating point stored in the output control means or an operating point close to the optimum operating point and the operating point. And a power control device that controls the power conversion means to store the voltage difference or the current difference between the compared operating points at 1% or more and 5% or less of the optimum operating point voltage or the optimum operating point current. You. The power control unit further includes an output control unit that detects an operating point of the input power, and a power conversion unit. The output control unit controls the power conversion unit based on a predetermined reference point, so that a plurality of operating points of the input power can be set. The output control means detects a current and a voltage at a plurality of the operating points and repeatedly performs a process of setting the operating point having the maximum power among the plurality of the operating points as a new reference point. In the power control apparatus that follows the maximum output point, the width between the voltage value at the operating point that is the longest from the reference point and the voltage value at the reference point among the plurality of operating points is the voltage at the reference point. 1% or more of the value 6
% By controlling the power conversion means to be less than or equal to%. Further, the apparatus has output control means for detecting the operating point of the input power and power conversion means, and the output control means controls the power conversion means based on a predetermined reference point to set the operating point of the input power to two.
The output control means detects current and voltage at two points of the operating point, obtains a current differential value of power from the two points of the operating point, and sets a new reference based on the current differential value of power. In a power control device that follows a maximum output point by repeatedly performing a process of setting a point, a voltage value at an operating point having the longest distance from the reference point and a voltage value at the reference point among a plurality of operating points. The power control unit controls the power conversion means so that the width of the power conversion unit is 1% or more and 5% or less of the voltage value at the reference point. If the current derivative of the power is zero, the predetermined reference point is set as the new reference point.If the current derivative of the power is greater than zero,
Of the two operating points, an operating point whose voltage is lower than the voltage at the predetermined reference point is set as the new reference point. If the current differential value of the power is smaller than zero, the two operating points are selected. Of these, it is preferable that an operating point whose voltage is higher than the voltage at the predetermined reference point be the new reference point.

Further, the input power is achieved by a power supply device that is a solar cell, a wind power generator, or a thermoelectric generator. Further, it is preferable that the solar cell is an amorphous semiconductor.

[0014]

It is generally said that the smaller the change in the operating point, the more power is extracted from the solar cell.

In this regard, according to the study of the present inventors, a sampling period of 1/30 s, which is commonly used, is generally used.
Under the condition of ec, if the magnitude of the change of the operating point is 1% of the value that the optimal operating voltage or the optimal operating current can take,
It has been found that the smaller the size, the more power can be extracted from the power supply, but if it is smaller than 1%, the power extracted from the power supply decreases. As a result of detailed investigation, it was found that the power reduction of 1% or less was due to a delay in response or an abnormal operation in searching for an optimum operating point. That is, when the magnitude of the change of the operating point becomes small, not only does the response become slow, but also it becomes impossible to normally track the optimal operating point due to the influence of the solar radiation fluctuation during the search, and the output power of the power supply decreases due to the occurrence. Happens.

In the power control device and the power supply device using the same according to the present invention, when the output control means sets the optimum operating point or a point closer to the optimum operating point, the output control means previously sets the optimum operating point or the optimum operating point. While setting the operating point determined to be closer to the optimal operating point or the optimal operating point from the operating point determined to be close to the operating point, the operation determined to be a point closest to the previous optimal operating point or the optimal operating point The optimum operating point voltage or current is calculated by taking the voltage or current difference between the operating point with the largest voltage or current difference from the previous operating point and the operating point determined to be close to the previous optimum operating point or optimum operating point. By setting the obtained value to 1% or more and 5% or less or 6% or less, it is possible to suppress a response delay or an abnormal operation in searching for an optimum operating point, and to extract more power from the power supply.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing an example of a power device using a power control device according to the present invention. In this power supply device, the output terminal of the solar cell 1 as a power supply is connected to the inverter 3 of the power conversion means 2, and the AC output of the inverter 3 is connected to the AC power system 10 via the transformer 9. The switching element used for the inverter 3 is an IGBT (Insulate).
d Gate Bipolar Transisto
r), GTO (Gate Turn Off), MOS
FET and the like. The output voltage and output current of power supply 1 are
It is detected and obtained by a voltage detecting means 6 for detecting a voltage of the output control means 5 and a current detecting means 7 for detecting a current. The detected voltage value Vs output from the voltage detecting means 6 and the detected voltage value Is output from the current detecting means are determined by MPP
It is input to the T control circuit 8. The MPPT control circuit 8 includes an A / D conversion circuit 11 for capturing a voltage value Vs and a current value Is of a power supply into a digital quantity, and a storage circuit for storing the voltage value Vs and the current value Is captured by the A / D conversion circuit 11. 12. Data is read from the storage circuit 12, a reference voltage Vref is calculated, a voltage command circuit 13 for outputting a command voltage, and the command voltage output from the voltage command circuit 13 is converted into a command voltage V ^* of a subsequent analog quantity ^. D to output as
The A / A conversion circuit 14, which can be easily realized by a one-chip microcomputer or a DSP, outputs a command voltage V ^* . The command voltage V ^* and the detected voltage value V output by the MPPT control circuit 8 of the maximum output control means.
The difference of s is input to the gate control circuit 4 of the power conversion means 2. The gate control circuit 4 controls the inverter 3 so that the detected voltage value Vs becomes equal to the command voltage V ^* . Specifically, the gate pulse applied to the switching element in the inverter 3 is controlled by changing the on / off duty ratio of the gate pulse by instantaneous current value control, sine wave triangular wave comparison, or the like.

In the power device having the above configuration, as a method of controlling the maximum output, a method is used in which the operating point of the solar cell 1 is changed at a plurality of points, and control is performed so that the output power becomes the voltage of the operating point having the maximum output power. Take. More specifically, a maximum output control algorithm of the power device will be described with reference to FIGS. The processing described below is repeatedly performed, and follows the maximum output point. Here, the MPPT control circuit 8 determines the optimum operating point or a point closer to the optimum operating point, and the operating point set there is referred to as a reference point. Further, in the output control means 5, when setting the reference point, during the time from setting the previous reference point to setting a new reference point, The distance of the previous reference point will be referred to as the maximum reference point isolation width. Also, at this time,
The voltage width is referred to as a maximum reference point isolation voltage width ΔVs, and the current width is referred to as a maximum reference point isolation current width ΔIs.

The control algorithm is as shown in FIG. First, as an initial setting process, the maximum reference point isolation voltage width ΔVs is set in advance to a value of 2% of the value considered as the optimum operating point voltage Vop. Further, the current voltage is read, and this is set as the reference voltage Vref, and the current operating point is set as the reference point. After performing this processing, the subsequent processing is repeatedly performed.

First, the command voltage V ^{* is changed} to the reference voltage Vref.
, The maximum reference point isolation change width ΔVs, which is 2% of the optimum operating point voltage Vop, is changed to be positive or negative, and the voltages Vs and the currents Is of a plurality of operating points are sequentially changed to (Vs ₁ , Is
₁ ), (Vs ₂ , Is ₂ )... In this example, the change in the command voltage V ^* is initially smaller than the reference voltage Vref by 2% of the optimum operating point voltage Vop from the reference voltage Vref, that is, the maximum reference point isolation voltage width ΔVs, as shown in FIG. The voltage Vs _{2 is} reduced to the voltage Vs ₂ , and then the voltage Vs ₃ is larger than the reference voltage Vref by 2% of the optimum operating point voltage Vop, that is, the maximum reference point isolation voltage width ΔVs.
To increase. During this change, the voltage Vs and the current Is are read and stored at a plurality of operating points. In this embodiment, the voltage Vs and the current Is at three operating points
Is read and stored.

Next, the read voltage Vsi and current Is
From i, the power Psi at each point is calculated by the following equation.

Psi = Vsi × Isi From the calculated power Psi, a point where the power is maximum is found, and the voltage at the operating point where the power is maximum is set as the next reference voltage Vref. In this case, the voltage becomes maximum power is Vs _3, the reference voltage Vref The voltage value of the next
And The reference voltage Vref determined in this way is
Set a new reference point as the command voltage V ^* .

The above processing is repeatedly performed, thereby following the maximum output point so that the output becomes maximum.

Here, the relationship between the output of the solar cell as a power supply and the maximum reference point isolation voltage width ΔVs will be described. FIG. 5 is a graph showing the relationship between the maximum reference point isolation voltage width ΔVs under a certain amount of solar light and the output power of the solar cell. The horizontal axis indicates the maximum reference point isolation voltage width ΔVs as a ratio to the optimum operating point voltage Vop. The vertical axis represents the amount of power obtained from the solar cell during a certain period of solar radiation as a ratio (power amount efficiency) to the maximum amount of power that can be extracted during that period.
To measure the power when the output is AC, at least one cycle time (20 ms at 50 Hz, 16.6 ms at 60 Hz) is required for one change of the operating point. Thus, the search method that requires three changes requires 1
The search time per time requires 60 ms in a system outputting 50 Hz AC, and 50 ms or more in a system outputting 60 Hz AC. If the search time is longer than this, the load may be the AC system. In FIG. 5, the sampling period is 33.3 ms, and the search time is 100 ms.

FIG. 5 indicates that the power efficiency is 99.6% when the maximum reference point isolation voltage width ΔVs is 1%, and the power efficiency drops sharply when the maximum reference point isolation voltage width ΔVs is smaller than 1%. You can see that If the solar light to the solar cell is almost constant, the smaller the maximum reference point isolation voltage width ΔVs is, the finer the search can be made, the better the energy efficiency is. However, in the case where the solar light changes like actual sunshine, the maximum is obtained. If the reference point isolation voltage width ΔVs is too small, an abnormal operation may occur in following the optimum operating point and deviate from the optimum operating point, and the response time is delayed, so that the energy efficiency is reduced as shown in FIG.

The maximum reference point isolation voltage width ΔVs is from 1% to 2
%, The power efficiency is reduced, but the degree of the reduction is small and a high power efficiency of 99.6% or more is obtained.

The maximum reference point isolation voltage width ΔVs is 2%
Above this, the greater the maximum reference point isolation voltage width ΔVs, the lower the power efficiency. For example, when the maximum reference point isolation voltage width ΔVs is 6%, the power efficiency is 99.0%. Therefore, in order to extract more power from the solar cell, it is desirable that the maximum reference point isolation voltage width ΔVs be 6% or less in the search algorithm of the present embodiment.

From the above, the maximum reference point isolation voltage width Δ
By setting Vs to 1% or more and 6% or less of the optimum operating point voltage Vop, 10 bits is enough for the resolution of the A / D conversion circuit. Maximum power can be extracted from the battery.

The maximum reference point isolation voltage width ΔVs is, for example, 2% of the optimum operating point voltage Vop. However, the optimum operating point voltage Vop changes under various conditions as described above, so the reference voltage is set. The maximum reference point isolation voltage width ΔVs may be set every time, but the magnitude of the change of the optimum operating point voltage Vop due to solar radiation fluctuation or temperature change is considerably smaller than the optimum operating point voltage Vop. The operating point voltage Vop may be regarded as a constant value and the maximum reference point isolation voltage width ΔVs may be set as a constant value, which does not depart from the gist of the present invention. Also, if the approximate magnitude of the optimum operating point voltage Vop is known, the maximum reference point isolation voltage width ΔVs may be set in advance; otherwise, the voltage value when operating at the optimum operating point is It is desirable to set the original.

(Embodiment 2) First, as an initial setting process, a maximum reference point isolation voltage width ΔVs is set. The maximum reference point isolation voltage width ΔVs is set to 2% of the value considered as the optimum operating point voltage Vop. At this time, as described in the first embodiment, the magnitude of change of the optimum operating point voltage Vop due to solar radiation fluctuation, temperature change, or the like is the optimum operating point voltage Vop.
Since it is smaller than the magnitude of p, the optimum operating point voltage Vo
Assuming that p is constant, the maximum reference point isolation voltage width ΔVs is set in advance as a constant value. Further, in order to use the current operating point as a reference point, a voltage is read and is set as a reference voltage Vref. After the above initial processing is completed, the subsequent processing is repeated.

First, the command voltage V ^* is set to a voltage value obtained by adding the maximum reference point isolation voltage width ΔVs to the reference voltage Vref (V
^* ← Vref + ΔVs). At this time, the voltage Vs ₁ and the current Is ₁ are read and stored. Next, the command voltage V ^*
Is the voltage value obtained by subtracting the maximum reference point isolation voltage width ΔVs from the reference voltage Vref (V * ← Vref−ΔVs). At this time, the voltage Vs ₂ and the current Is ₂ are read and stored.

Next, using the voltages and currents of the two operating points that have just been read, Vav, which is the average voltage of the two operating points,
An average current Iav between two operating points, ΔV which is a difference between voltages of two operating points, and ΔI which is a difference between currents of two operating points are calculated. That is, an operation represented by the following equation is performed.

Vav = (Vs ₁ + Vs ₂ ) / 2 Iav = (Is ₁ + Is ₂ ) / 2 ΔV = Vs ₁ −Vs ₂ ΔI = Is ₁ −Is ₂ The thus obtained Vav, Iav, ΔV, From ΔI, a current differential value dP / dI of power is obtained as in the following equation.

DP / dI = Vav + Iav × (ΔV / ΔI) Here, the change of the operating point is a voltage change, which is very small, 4% of the optimum operating point voltage Vop. / DI can be regarded as a current differential value of electric power.

When the operating point reaches the optimum operating point, the current derivative dP / dI of the power obtained here becomes zero, and the output voltage of the solar cell becomes maximum. Current differential value dP of electric power
When / dI is zero, the reference voltage V
ref is not changed. When the current differential value dP / dI of the power is greater than zero, the current may be increased, that is, the reference voltage Vref may be decreased. When dP / dI is less than zero, the current may be decreased, that is, the reference voltage Vref
ref may be increased. The amount of change in the reference voltage Vref is the maximum reference point isolation voltage width ΔVs. This can be summarized as follows.

When dP / dI = 0, Vref is unchanged. When dP / dI> 0, Vref ← Vref−ΔVs. When dP / dI <0, Vref ← Vref + ΔVs. Value V ^*
And set a new reference point. By repeating such processing, the optimum operating point is followed, and the output is maximized.

Here, the relationship between the solar cell output and the maximum reference point isolation voltage width ΔVs will be described. FIG. 7 is a graph showing the relationship between the maximum reference point isolation voltage width ΔVs and the solar cell output in this control method for maximizing the output power,
The horizontal axis represents the maximum isolation voltage width ΔVs as a percentage of the optimum operating point voltage Vop, and the vertical axis represents the amount of power that can be extracted from the solar cell in a certain period under a certain amount of sunshine. (Power efficiency). This embodiment also has a control system similar to that of the first embodiment.

According to FIG. 7, the maximum reference point isolation voltage width ΔV
When s is 1%, the power efficiency is 99.0%. When the maximum reference point isolation voltage width ΔVs is smaller than 1%, the power efficiency is significantly reduced. This is because the maximum reference point isolation voltage width ΔVs is small, so that the optimum operating point search may be abnormally operated under the influence of the solar light fluctuation, and the power efficiency is reduced due to the slow response.

The maximum reference point isolation voltage width ΔVs is from 1% to 2
While the power efficiency is lower than a little over%, the degree is small, and the power efficiency is 99.0% or more.

When the maximum reference point isolation voltage width ΔVs is 2% or more, the amount of electric power decreases rapidly as the magnitude increases. For example, the maximum reference point isolation voltage width ΔVs is 5% and the power efficiency is 99.0%. To extract the maximum power from the solar cell, the maximum reference point isolation voltage width ΔVs is set to about 5% or less. In this case, when the maximum reference point isolation voltage width ΔVs is 2.5%, the most power can be extracted.

As described above, the maximum reference point isolation voltage width ΔV
By setting s to be 1% or more and 5% or less of the optimum operating point voltage Vop, a large amount of power can be extracted from a solar cell or the like, which is a power supply, using inexpensive components having not so high resolution.

In the above example, an amorphous solar cell is used as a solar cell, but the voltage-power characteristic of the amorphous solar cell is smaller than that of a crystalline solar cell with respect to a voltage change near an optimum operating point. The change in output power is small, and the maximum output can be more efficiently extracted.

(Embodiment 3) Still another example of the power supply device according to the present invention will be described. This power supply device has a configuration as shown in FIG. 8. The output terminal of the solar cell 1 as a power supply is connected to a chopper 15 that outputs DC power, and the output terminal of the chopper 15 is connected to a DC load 16. Connected. The maximum output control circuit 5 according to the first or second embodiment
The control is performed so that the maximum output from the solar cell 1 is obtained. Also. In this power supply,
As a method of controlling the maximum output, as in the first embodiment, a method of changing the operating point of the solar cell 1 by a plurality of points and controlling such that the output power becomes the voltage of the operating point where the output power is the maximum.

The relationship between the power efficiency of the solar cell output and the maximum reference point isolation voltage width ΔVs in the power supply device having such a configuration is the same as that described in the first embodiment, and the maximum reference point isolation voltage width ΔVs is 1 %, The energy efficiency decreases. Therefore, by setting the maximum reference point isolation voltage width ΔVs to be 1% or more and 6% or less of the optimum operating point voltage Vop, the maximum power can be extracted from the solar cell without using expensive high-precision parts.

By the way, in the present embodiment, DC is output from the power conversion means 2, so that the search time can be shortened and the response can be made faster than the output of AC 50Hz or 60Hz. Is required, and the cost increases.

[0047]

As described above, the output control means for detecting the operating point of the input power, the optimum operating point stored in the output control means or the operating point close to the optimum operating point is compared with the operating point. 1% of the optimum operating point voltage or the optimum operating point current storing the voltage difference or the current difference between the compared operating points.
By controlling the power conversion means to 5% or less or 6% or less, the control system is composed of inexpensive parts with a not so high resolution by the power control device.
Power can be extracted very efficiently from a solar cell or the like as a power supply.

In addition, by using a non-single-crystal semiconductor as the solar cell, a decrease in power when the operating point is changed is small, and the power of the solar cell can be more efficiently extracted.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a graph of a voltage-current characteristic and a voltage-power characteristic of a solar cell.

FIG. 3 is a flowchart of the maximum output control of the embodiment according to the present invention.

FIG. 4 is a diagram showing a time chart of the embodiment according to the present invention.

FIG. 5 is a diagram of ΔVs / Vop-power efficiency characteristics of the example according to the present invention.

FIG. 6 is a flowchart of a maximum output control of another embodiment according to the present invention.

FIG. 7 shows ΔVs / Vop− of another embodiment according to the present invention.
It is a figure of an electric energy efficiency characteristic.

FIG. 8 is a diagram showing another power supply device of the present invention.

[Description of Signs] 1 solar cell 2 power conversion means 3 inverter 4 gate control circuit 5 maximum output control means 6 voltage detection means 7 current detection means 8 MPPT control circuit 9 transformer 10 AC power system 11 A / D conversion circuit 12 storage circuit 13 Voltage command circuit 14 D / A conversion circuit 15 Chopper 16 DC load

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05F 1/67

Claims (6)

(57) [Claims] An output control means for detecting an operating point of input power, an optimum operating point stored in the output control means or an operating point close to the optimum operating point is compared with the operating point. A power control device for controlling a power conversion unit to an optimal operating point voltage or an optimal operating point current of 1% or more and 5% or less of an operating point voltage difference or a current difference. 2. An output control means for detecting an operating point of input power.
Stage and power conversion means, and the output control means
Input by controlling the power conversion means based on the reference point
The operating point of the power is changed by a plurality of points, and the output control means
By detecting current and voltage at a plurality of operating points,
The operating point with the highest power among the multiple points
Maximum output point by repeating the process of setting the reference point
In the power control device that tracks the operating point, of the plurality of operating points,
Voltage value at the operating point and the voltage value at the reference point.
Is between 1% and 6% of the voltage value at the reference point.
Controlling the power conversion means so that
Power control device. 3. An output control means for detecting an operating point of input power.
Stage and power conversion means, and the output control means
Input by controlling the power conversion means based on the reference point
The operating point of the power is changed by two points, and the output control means
Detecting the current and the voltage at the two points,
The current differential value of the power is obtained from the two points
Repeat the process of setting a new reference point based on the minute value
By doing this, the power controller that follows the maximum output point
And Of the plurality of operating points, the most distant from the reference point
Voltage value at the operating point and the voltage value at the reference point.
Is between 1% and 5% of the voltage value at the reference point
Controlling the power conversion means so that
Power control device. 4. When the current derivative of the power is zero,
Using the predetermined reference point as the new reference point,
If the current derivative is greater than zero, the two operating points
Voltage is smaller than the voltage at the predetermined reference point.
Before operating point Note that a new reference point is used to calculate the current derivative of the power.
If the value is smaller than zero, the electric power of the two operating points
Operating point where the pressure is greater than the voltage at said predetermined reference point
Is set as the new reference point.
The power control device according to any one of the preceding claims. 5. The method according to claim 1, wherein the input power is a solar cell, a wind generator,
The power control device according to any one of claims 1 to 4, wherein the power control device is a thermoelectric generator. 6. The power control device according to claim 5, wherein the solar cell is an amorphous semiconductor.