JP3145883B2 - Inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for converting DC power generated by a solar cell into AC power and supplying power to a general AC load for home use, office use, or an existing commercial power system. In particular, the present invention relates to an inverter device that performs maximum power point tracking control.

[0002]

2. Description of the Related Art In order to supply power from a solar cell to a general AC load for home use or a commercial power system, an inverter device for converting the DC power into AC power is required. In the inverter device, generally, maximum power point tracking control is performed in order to maximize the power extracted from the solar cell. That is, the DC power extracted from the solar cell is detected, and the inverter is controlled so that the power is maximized.

FIG. 6 is a block diagram showing a conventional example of an inverter device. DC power of solar cell 2 is inverter 1
And the fluctuation of the voltage is suppressed by the DC capacitor 4. The high-frequency inverter bridge 5 converts the high-frequency AC (several tens to several hundreds of kHz) into a high-frequency transformer 6 having a function of insulating the solar cell 2 (primary side) from the commercial power system 3 (secondary side). It is supplied to the primary side. The high-frequency voltage input to the high-frequency transformer 6 is transformed and output from the secondary side of the high-frequency transformer 6 and rectified in the diode bridge 7. Then, a high frequency component contained in the full-wave rectified waveform is removed and smoothed by a filter circuit including the DC reactor 8 and the capacitor 24 connected in parallel. Then, the low frequency inverter bridge 9 causes the low frequency (50/60 to several hundred H)
The return is controlled in z), converted into a low frequency sine wave alternating current, and output to the interconnection relay 10. In the interconnection relay 10, the interconnection between the commercial power system 3 and the inverter 1, that is,
The DC power of the solar cell 2 is supplied to the commercial power system 3, and the commercial power system 3 is disconnected from the inverter 1 when the output of the solar cell is reduced. Also,
A DC input current detector 12 is connected to a stage preceding the high-frequency inverter bridge 5, and an inverter output current detector 13 is connected to a primary side or a secondary side of the high-frequency transformer 5.

[0004] The switching elements S1 to S4 of the low-frequency inverter bridge 9 output signals generated by the gate drive signal generation unit 22 according to the return control performed by the return control unit 23 in the control circuit 14 based on the commercial power system voltage signal. Is turned on / off.

[0005] The switching elements Q1 to Q4 constituting the high-frequency inverter bridge 5 include a PWM modulation control section 16
On / off control is performed by a signal generated by the gate drive signal generation unit 15 based on the pulse train generated in the above. The control amount at this time is the duty ratio of the pulse train signal obtained by the PWM modulation control, that is, the ratio of the amplitude of the sine wave signal to the amplitude of the carrier signal. The PWM modulation control unit 16 changes the control amount to
Feedback control is performed that adjusts the inverter output current signal I _t to be detected by the inverter output current detector 13.

FIG. 7 is a view showing a solar cell characteristic curve.
The vertical axis a DC input current I _{I N} detected by the DC input current detector 12 of FIG. 6, the horizontal axis represents the DC input voltage V _{I N} detected from both ends of the DC capacitor 4 in Fig.
In addition, two characteristic curves L ₁ and L ₂ at the solar radiation intensities E1 and E2 and the element temperature t ° C. are shown. The operating point on the solar cell characteristic curve moves to an arbitrary point by changing the control amount. For example, the solar radiation intensity is E1, the control amount is K ₁
When the operating point of the case of the P _1, if the solar radiation intensity is changed to E2, if the control amount K ₁ is constant, the operating point will move to P ₁ 'on the characteristic curve L _2. Similarly, operating points P ₂ (control amount K ₂ ), P ₃ on operating point characteristic curve L ₁
(Control amount K ₃ ) indicates that the operating points P ₂ ′ and P ₃ ′ on the characteristic curve L ₂ when the solar radiation intensity changes from E1 to E2.
Move to

Next, maximum power point tracking control for extracting maximum power from the solar cell 2 will be described. DC input and the DC input voltage V _{I N} in FIG. 6 the current I _{I N} control circuit 14
Is input to DC input The power calculating section 18 voltage V _{I N}
DC power P from the product of the DC input current I _{I N} is calculated and,
The value is temporarily stored in the power comparison unit 19. The power comparison unit 19 compares the previously calculated and temporarily stored DC power _Pb with the currently calculated DC power _Pn . From the increase / decrease of the power obtained here and the sign of increase / decrease of the control amount up to the previous time temporarily stored in the control amount calculating unit 17,
The control amount of the inverter is newly determined. Then, by changing the duty ratio of the pulse train signal obtained by the PWM modulation controller 16 according to the newly determined control amount, the solar cell operating point on the solar cell characteristic curve is changed,
The maximum power point at which the output of the solar cell 2 becomes maximum is tracked.
The above operation is repeatedly performed at a constant sampling time.

FIG. 8 is a diagram showing a relationship between a control amount and an operating point on a solar cell characteristic curve. The horizontal axis of the DC input voltage V _{I N} in FIG. 6, the vertical axis represents the DC power calculated by the power calculation unit 18. At an arbitrary operating point A on the solar cell characteristic curve, the switching element of the high-frequency inverter bridge 5 is turned on / off by the PWM modulation control with the control amount KA.
It is assumed that off control is performed. Further, at this point A, when the control amount is changed by + △ K, the power that can be taken out of the solar cell 2 increases, and the operating point moves to the point B. At this time, the previous power value PA is compared with the current power value PB, and the power is increasing, and the sign of the increase or decrease of the control amount when moving from the point A to the point B is positive (+ △ K)
Therefore, the control amount is newly changed by + ΔK. Next, when the PWM modulation control is performed with the newly determined control amount and the inverter 1 is switched, the operating point moves to the point C. At point C, like point B,
Since the power increases and the increase / decrease sign of the control amount is positive, the control amount is further changed by + ΔK. Then, the operating point moves to the point D. At point D, as a result of comparison with the previous power value PC, the power has decreased, and when moving from point C to point D, the sign of increase or decrease of the control amount is positive (+ △ K). The control amount is changed by -ΔK. By repeating the above processing, the operating point is tracked to the maximum power point at which the maximum power can be extracted.

FIG. 9 is a flowchart of the above processing procedure. First, compared with the DC power P _n, which is calculated this time and the DC power P _b temporarily stored previously calculated by the power comparing unit 19 of FIG. 6, then the previously calculated temporarily in the control amount calculation unit 17 of FIG. 6 With reference to the stored control amount increase / decrease sign dK,
The present control quantity K _n is determined. Thereafter, the current P _n , dK, and K _n are temporarily stored for the determination of the control amount at the next time. The above processing is repeatedly performed at every fixed sampling time.

[0010]

However, in the conventional inverter device, the electric power that can be taken out of the solar cell 2 varies according to the solar radiation intensity and the element temperature. As shown in the flowchart of FIG. 9, since the next control amount is determined from the increase / decrease sign of the increase / decrease of the solar cell power between the previous time and the present time, the controllability in the maximum power point tracking control is determined. Is extremely bad, and when the operating point greatly deviates from the maximum power point as in the case of sudden change in solar radiation, it takes too much time to reach the vicinity of the maximum power point next time. In particular, when the sun appears and disappears from between the clouds, it often hardly reaches the maximum power point, and there is a problem that control responsiveness is extremely deteriorated.

When the solar radiation intensity is stable, it is necessary to reduce the voltage fluctuation near the maximum power point voltage in order to always keep the operating point at the maximum power point.
That is, it is necessary to make the value of the variation ΔK of the control amount as small as possible. On the other hand, when the solar radiation intensity changes suddenly, the operating point moves to a position away from the maximum power point, so it is necessary to control the operating point to move to the next maximum power point at high speed. There is. In this case, the value of the change amount ΔK of the control amount must be as large as possible. However, in the conventional inverter device, since the change amount ΔK of the control amount is a constant value, if the change amount ΔK of the control amount is set small so as to enhance the control stability near the maximum power point, the change from the maximum power point If they are separated, the control response to reach the maximum power point becomes worse, and vice versa, that is,
If the variation ΔK of the control amount is set large so as to increase the control stability near the maximum power point, the voltage fluctuation near the maximum power point increases, and the control stability near the maximum power point deteriorates. There was a problem.

[0012] As an inverter device for solving the above-mentioned problems, according to the magnitude of the change in the DC power from the solar cell,
An inverter device that determines a change amount of a control amount is known (Japanese Patent Publication No. 5-68722). In this inverter device, when the DC power greatly changes due to an increase or decrease in the insolation intensity, and the operating point moves away from the maximum power point, the amount of change in the control amount is increased to quickly bring the operating point closer to the maximum power point. Control. However, also in this inverter device, the control amount is simply changed according to the magnitude of the change amount of the DC power, and the target value of the control amount is not determined, so that the control responsiveness and the control stability are insufficient. Was.

By the way, when the sunlight intensity and the element temperature change, the characteristic curve of the solar cell changes. FIG. 2 is a characteristic curve (PV curve) showing the simulation results of the solar cell characteristics under various conditions (sunlight intensity, element temperature), and a cross in the figure indicates the maximum power point in each characteristic curve. Is shown.
As can be seen from this figure, the maximum power point falls within a substantially constant voltage range even when the solar radiation intensity or the element temperature changes.

The present invention has been made to solve the above problems.
It was created in consideration of the properties of the above solar cell, control stability near the maximum power point, and by improving the control responsiveness away from the maximum power point,
An object of the present invention is to provide an inverter device that can efficiently extract maximum DC power from a solar cell.

[0015]

According to the first aspect of the present invention, there is provided an inverter device which changes a control amount in PWM modulation control.
The maximum DC power extracted from the solar cells
While converting the DC power to AC power.
To replace the load or the existing supply to the commercial power grid.
In the inverter device, the solar cell is converted to an inverter.
The amount of change of the control amount based on the input DC input voltage
Control means for determining
Maximum power point voltage as a reference for determining the amount of change
Means for pre-specifying a range, the DC input voltage and the
Means for comparing with a high power point voltage range;
If the pressure is within the maximum power point voltage range, the control
The change in the DC input voltage is set to a small
When the voltage is outside the high power point voltage range, the amount of change in the control amount
Control amount setting means for setting a large value of
It is characterized by. The inverter device according to claim 2 is a contractor.
2. The inverter device according to claim 1, wherein the maximum power
When the voltage is outside the point voltage range, the variation of the control amount is constant.
It is characterized by the value. The invar according to claim 3.
The control device changes a control amount in the PWM modulation control.
This maximizes the DC power extracted from the solar cells.
The DC power is converted to AC power while controlling
Supply to the load or existing commercial power grid.
In the converter, the solar cell enters the inverter.
Change amount of the control amount based on the input DC input voltage.
Control means for determining, wherein the control means
Maximum power point voltage range that is a reference for determining the amount of change in
Means for designating the enclosure, and approximately the middle of the maximum power point voltage range.
Value obtained by weighting the difference between
From the maximum power point.
Control amount setting means for setting by making
It is characterized by. The inverter device according to claim 4, wherein P
By changing the control amount in the WM modulation control,
Control to maximize the DC power taken from solar cells
While converting the DC power to AC power,
Or for inverter equipment to supply to existing commercial power systems
The DC input from the solar cell to the inverter
Control for determining a change amount of the control amount based on an input voltage
Means for controlling the amount of change in the control amount.
Specify the maximum power point voltage range that serves as the reference for
Means, the DC input voltage and the maximum power point voltage range,
Means for comparing the DC input voltage with the maximum power point
If it is within the voltage range, reduce the change amount of the control amount.
The DC input voltage is outside the maximum power point voltage range.
, A voltage approximately in the middle of the maximum power point voltage range
From the value obtained by weighting the difference between
Control amount setting means for setting a large amount of change in the control amount;
It is characterized by comprising.

[0016]

[0017]

[0018]

[0019]

The function of the characteristic curve of the solar cell shown in FIG . 2 is used.
The maximum power point voltage range is specified in advance, and the DC input voltage and
The DC input voltage is compared with the maximum power point voltage range.
If the voltage is within the maximum power point voltage range of
The DC input voltage is outside the maximum power point voltage range
In such a case, the control amount is largely changed. Also, the maximum power point
Weights the difference between the voltage approximately in the middle of the voltage range and the DC input voltage
The amount of change of the control amount from the value
Is also good. This allows the operating point to be close to the maximum power point.
Can accurately follow the maximum power point,
Operating point is the maximum power point due to changes in temperature or element temperature
Operating point near the maximum power point.
It can be moved at high speed.

[0020]

[0021]

[0022]

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the inverter control device according to the present invention will be described below. FIG. 1 is a circuit diagram showing the inverter device of the present embodiment. However, the same parts as those in FIG. 6 are denoted by the same symbols.

The inverter 1 converts the DC power output from the solar cell 2 into the same phase and frequency 50 as the commercial power system 3.
The power is converted into AC power having a frequency of / 60 Hz and supplied to the commercial power system 3. The configuration of the inverter 1 includes a DC capacitor 4 that suppresses fluctuations in DC power input from the solar cell 2 and a high-frequency alternating current (several tens to
High frequency inverter bridge 5 for converting to several hundred kHz)
And solar cell 2 (primary side) and commercial power system 3 (secondary side)
High-frequency transformer 6 having the role of insulating the rectified waveform, a diode bridge 7 for rectifying the insulated high-frequency alternating current, and a capacitor connected in parallel with the DC reactor 8 for the purpose of removing and smoothing the high-frequency components contained in the rectified waveform. 24
A low-frequency inverter bridge 9 that controls the DC output of the filter circuit at a low frequency (50/60 to several hundred Hz) to obtain a low-frequency sine-wave alternating current; and a commercial power system. 3, an AC relay 11, a DC input current detector 12, an inverter output current detector 13, a high frequency inverter bridge 5, and a low frequency inverter bridge 9.
And a control circuit 14 for controlling the above.

The control circuit 14 includes a gate drive signal generator 15 for generating a pulse train signal for controlling on / off of the high-frequency inverter bridge 5, a PWM modulation controller 16 for performing PWM modulation from a carrier signal and a sine wave signal, and a PWM controller.
A control amount calculation unit 17 that determines a control amount represented by a ratio of the amplitude of the sine wave signal to the amplitude of the carrier signal used in the modulation control, and the DC input voltage V _I of the solar cell 2
A power calculating unit 18 for calculating a DC power from the _N and the DC input current I _{I N,} the power comparing unit 19 for comparing the DC power DC power and have the previously calculated temporary storage calculated in the power calculating unit 18 A voltage range setting unit 20 for specifying the maximum power point voltage range, a voltage comparison unit 21 for comparing the DC input voltage with the maximum power point voltage range specified by the voltage range setting unit 20, and a low frequency inverter bridge 9 A gate drive signal generation unit 22 for generating a pulse train signal for controlling ON / OFF of the signal, and a loopback control unit 23.

Next, the control operation will be described. DC input voltage V detected from both ends of DC capacitor 4 in FIG.
_{I N} and the DC input current detected by the DC input current detector 12 I _{I N} is input to the power calculating section 18 of the control circuit 14. The power calculating section 18, the DC power P _n from the product of the DC input voltage V _{I N} and the DC input current I _{I N} is calculated and temporarily stored in the power comparing unit 19. In the voltage comparator 21 is compared with the maximum power point voltage range specified by the DC input voltage V _{I N} and a voltage range setting unit 20, the DC input voltage V _{I N} is equal outside the maximum power point voltage range, DC and controls the amount of decisions based on the input voltage V _{I N} in the control amount calculation unit 17, also a DC DC input voltage V _{I N} is within the maximum power point voltage range, which has been temporarily stored in the power comparing unit 19 The control amount is determined by the control amount calculation unit 17 based on the electric power _Pn . Then, PWM modulation control is performed based on the control amount, and a gate drive signal for controlling on / off of the high-frequency inverter bridge 5 is generated. In PWM modulation control, since the input to the inverter output current signal I _t from the inverter output current detector 13, the feedback control is realized.

Next, the setting of the maximum power point voltage range will be described in detail. When the solar radiation intensity and the element temperature change, the solar cell characteristic curve changes as shown in FIG.
The maximum power point (x part) in FIG. 2 is in a substantially constant voltage range (185 V to 200 V) even when the solar radiation intensity and the element temperature change.
Fits in. In this example therefore, ~V V _{p 1} the maximum power point voltage range on the solar cell characteristic curve as shown in FIG. 3 _{p 2} (V
_{p 1} = 175 V, V _{p 2} = 210 V). This maximum power point voltage range changes depending on the operating characteristics of the solar cell 2. Here, the simulation is performed, and the maximum power point voltage range is set based on the result, but may be set based on the experimental result. Further, the voltage may be set by analyzing the control data during the operation of the inverter 1 by the voltage range setting unit 20.

Next, the control amount will be described in detail. The control amount in this example is a ratio of the amplitude of the sine wave signal to the amplitude of the carrier signal used for performing the PWM modulation control. Since the amplitude value of the carrier signal is a constant value, the change in the control amount is It is represented by a change in signal amplitude. That is, if PWM modulation control is performed with a sine wave signal having a small amplitude value, the output of the inverter 1 will be small, and if PWM modulation control is performed with a sine wave signal having a large amplitude value, the output of the inverter 1 will be large. In this embodiment, the control amount is set to 100 levels for the inverter rated output current of 0 to 20 A (effective value).

The amount of change in the control amount is an amount by which the control amount is increased or decreased so that the operating point on the solar cell characteristic curve approaches the maximum power point. Usually, the controlled variable K _n is the controlled variable K _b previously determined
And the amount of change. Sunshine intensity and element temperature is constant, does not vary the maximum power point, when the DC voltage V _{I N} is within the maximum power point voltage range, the control stability is required in the operating point near the maximum power point . Therefore, in this case,
It is desirable that the amount of change ΔK _p is a minute constant amount. Meanwhile, solar irradiance or device temperature changes, if the voltage of the maximum power point fluctuates greatly, the DC input voltage V _{I N} is the maximum power point voltage range. At this time, in order to move the operating point to the vicinity of the maximum power point as quickly as possible as the operating point is further away from the maximum power point voltage range, that is,
In order to bring the DC voltage close to the maximum power point voltage range at a high speed, it is desirable to set the control variable change amount ΔK _v to be large. Also, as the operating point approaches the maximum power point, so that the operating point does not greatly exceed the maximum power point,
That is, it is desirable to set the variation ΔK _v of the control amount small so that the DC voltage does not deviate from the maximum power point voltage range. As described above, the amount of change ΔK _v is changed depending on how far the operating point is from the maximum power point voltage range. In this example, the amount of change ΔK _{v is set} to approximately the middle of the maximum power point voltage range. The difference is determined by weighting the difference between the voltage and the operating point voltage. This weighting is shown in FIG.
The function vK _v = f (△ V) shown in FIG. That is, the absolute value △ V of the difference substantially between the intermediate voltage V _{p a} and the DC input voltage V _{I N} of the maximum power point voltage range, △ V and 4 of the function f (△ V) because △ K _v Seeking. here,
The intermediate voltage in the maximum power point voltage range is V _{p a} = 192.5 V
It is. 4 are V ₁ = 12.5 V, V 2 = 2
5V, is set to △ K _{m a x} = 10.

Next, a method of determining a control amount in the control circuit section 14 of FIG. 1 will be described. FIG. 5 is a flowchart showing the determination method. First, the detected DC input voltage V _I
And _N, and the maximum power point voltage range V _{P 1} ~V _{P 2} set by the voltage range setting unit 20 of FIG. 1 are compared. Here, if the DC input voltage V _{I N} is out of the maximum power point voltage range, the absolute value of the difference substantially between the intermediate voltage V _{p a} an operating point voltage, that is, the DC input voltage V _{I N} of the maximum power point voltage range △ determine the control amount of variation △ K _v by performing weighted V, to determine the present control quantity K _n. Here, the change amount of the control amount △ K _v
Is obtained by substituting ΔV into the function ΔK _v = f (ΔV) shown in FIG. In addition, the change amount of the control amount ΔK _v
Increase or decrease of either V _{p a} -V _{I N} from the intermediate voltage V _{p a} minus DC input voltage V _{I N} is positive is determined by whether it is negative. Then, the previous control amount K _b and the change amount of the control amount △
The present control quantity K _n in the control amount calculation unit 17 of FIG. 1 by K _v
To determine. After the decision, the DC power P for determination of the next control amount, the control amount K _n, and change sign dK between the current and the previous control amount is temporarily stored.

On the other hand, the DC input voltage V _{I N} is the maximum power point voltage range, first in the power comparing unit 19 of FIG. 1 previously calculated temporarily stored DC power P _b and the current calculated DC power P _n is compared. And the comparison result of the DC power, the control amount calculation unit 17 of FIG. 1, on the basis of the change sign dK of previously calculated temporarily stored control quantity to determine the present control quantity K _n. The controlled variable K _n is determined from the previous control amount K _b a constant value a is controlled amount of variation △ K _p. Finally, as with the DC input voltage V _{I N} is out of the maximum power voltage range, the DC power P, which are currently obtained for determination of the next control amount, the control amount K _n, and the control amount of change sign dK is temporarily stored. The above processing is repeated at regular intervals. Here, by making the certain time as short as possible, the control stability of the operating point near the maximum power point can be improved.

[0032] As described above, in this example, to specify the maximum power point voltage range, when the DC input voltage V _{I N} is outside the maximum power point voltage range, the intermediate voltage of the maximum power point voltage range V as the difference between _{p a} and the DC input voltage V _{I N} is large,
Since the amount of change ΔK of the control amount is increased, the operating point can be moved faster near the maximum power point. Also,
Intermediate voltage of the maximum power point voltage range V _{p a} and the DC input voltage V
As the difference between _{I N} is small, to reduce the variation △ K of the controlled variable, the less it too went for the maximum power point, it is possible to enhance the control response. Further, when the DC input voltage V _{I N} is near the maximum power point, since the use of power comparison method only the maximum power point voltage range, that less of the variation of the operating point voltage, enhanced control stability it can.

In this embodiment, the amount of change in the control amount when the operating point is near the maximum power point is determined by the DC power which is the product of the DC input voltage and the DC input current. You may decide.

The change amount of the control amount is not limited to the method shown in the flowchart of FIG. 5, but may be determined by the following method, for example.

The method of DC input voltage V _{I N} is a constant value the amount of change when in the out of range maximum power point voltage. However, the constant value, the DC input voltage V _{I N} is previously set to be larger than the amount of change when within the maximum power point voltage range.

[0036] If the DC input voltage V _{I N} is within the maximum power point voltage range also, the amount of change control amount, the DC input voltage V
_{I N} and a reference voltage (e.g., a substantially intermediate voltage of the maximum power point voltage range in Fig. 2) a method of determining by performing weighted to the difference between.

[0037]

As described above, according to the present invention, the amount of change in the control amount is changed by the DC input voltage input from the solar cell to the inverter, so that the operating point is near the maximum power point on the solar cell characteristic curve. Can make the operating point more closely follow the maximum power point, and if the operating point moves away from the maximum power point due to changes in solar radiation intensity or element temperature, etc. Can be moved. Therefore, the DC power of the solar cell can be efficiently extracted and supplied to a load or a commercial power system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an inverter device according to the present invention.

FIG. 2 is a diagram showing a solar cell characteristic curve (PV curve).

FIG. 3 is a diagram showing a maximum power point voltage range on a solar cell characteristic curve (PV curve).

FIG. 4 is a diagram showing a function f (△ V) for determining a change amount of a control amount.

FIG. 5 is a flowchart showing a method for determining a change amount of a control amount in FIG. 1;

FIG. 6 is a block diagram showing a conventional inverter device.

FIG. 7 is a diagram showing a solar cell characteristic curve (IV curve).

8 is a diagram showing a solar cell characteristic curve (PV curve) for explaining the control method of FIG. 6;

FIG. 9 is a flowchart showing a conventional control method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Inverter 2 Solar cell 3 Commercial power system 12 DC input current detector 13 Inverter output current detector 14 Control circuit 15 Gate drive signal generation part 16 PWM modulation control part 17 Control amount setting part 18 Power calculation part 19 Power comparison part 20 Voltage range setting unit 21 voltage comparator V _{I N} DC input voltage

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Satoshi Fujii 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-6-83465 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G05F 1/67

Claims (4)

(57) [Claims] 1. A method according to claim 1, further comprising: changing a control amount in the PWM modulation control to convert the DC power into AC power while controlling the DC power extracted from the solar cell to be a maximum, thereby obtaining a load or existing commercial power. In an inverter device for supplying power to a grid, a DC input voltage input from the solar cell to an inverter.
Control means for determining the amount of change in the control amount based on
And the control means is configured to determine a change amount of the control amount.
Means for designating a reference maximum power point voltage range in advance, and comparing the DC input voltage with the maximum power point voltage range.
Means when the DC input voltage is within the maximum power point voltage range.
In this case, set the variation of the control
If the power voltage is outside the maximum power point voltage range,
Control amount setting means for setting a large change amount of the control amount.
An inverter device comprising: an inverter; 2. When the voltage is outside the maximum power point voltage range,
Is characterized in that the change amount of the control amount is set to a constant value.
The inverter device according to claim 1. 3. The control amount in PWM modulation control is changed.
The maximum DC power extracted from the solar cells.
The DC power is converted to AC power while controlling so that
Convert and supply to load or existing commercial power system
In the inverter device, a DC input voltage input to the inverter from the solar cell
Control means for determining the amount of change in the control amount based on
And the control means is configured to determine a change amount of the control amount.
Means for designating a reference maximum power point voltage range; and a voltage substantially intermediate between the maximum power point voltage range and the DC input.
The change in the control amount from the value obtained by weighting the difference from the voltage
Control by changing the amount toward the maximum power point
And an amount setting means.
Data device. 4. A control amount in PWM modulation control is changed.
The maximum DC power extracted from the solar cells.
The DC power is converted to AC power while controlling so that
Convert and supply to load or existing commercial power system
In the inverter device, a DC input voltage input to the inverter from the solar cell
Control means for determining the amount of change in the control amount based on
And the control means is configured to determine a change amount of the control amount.
Means for designating a reference maximum power point voltage range, and comparing the DC input voltage with the maximum power point voltage range.
Means when the DC input voltage is within the maximum power point voltage range.
In this case, set the variation of the control
If the power voltage is outside the maximum power point voltage range,
A voltage approximately in the middle of the maximum power point voltage range and the DC input voltage
The amount of change in the control amount is calculated from the value obtained by weighting the difference from
Control amount setting means for setting a large value.
Features inverter device.