WO2012137403A1

WO2012137403A1 - Power converter and solar power generation system

Info

Publication number: WO2012137403A1
Application number: PCT/JP2012/001383
Authority: WO
Inventors: 塩田　奈津子; 木戸　稔人
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2011-04-01
Filing date: 2012-02-29
Publication date: 2012-10-11
Also published as: JPWO2012137403A1; JP5093425B1

Abstract

This power converter performs power conversion of input power that is input as direct current power and creates an output. The power converter has an input current integrated detection unit that detects an input current integrated value which is a value integrated over a prescribed time period for an input current, which is the current for input power, a plurality of power conversion circuit units that perform power conversion of the input power and have different input current ranges from each other and overlapping parts with the input current range of adjacent power conversion circuit units, and a power conversion control unit that selects one power conversion circuit unit from the plurality of power conversion circuit units on the basis of the detected input current integrated value and carries out control at control conditions that obtain the maximum output power for the selected power conversion circuit unit.

Description

Power converter and solar power generation system

The present invention relates to a power conversion device that converts input power input as DC power and outputs the power, and a solar power generation system using the power conversion device.

In recent years, in order to cope with the depletion of fossil fuels, the spread of renewable natural energy is desired due to the need for environmental considerations. In particular, solar cells have little impact on the environment, and further development is expected in the future. The electric power generated by the solar battery is effectively used by being stored in a storage battery or sold to an electric power company. Since the output of a solar cell varies depending on the amount of solar radiation, the output depends on the weather and the like, so it is difficult to control the amount of power supplied. It is preferable that the output is taken out with high conversion efficiency over the entire fluctuation range of the output of the solar cell.

FIG. 21 is a graph showing an example of characteristics of a general solar cell. In FIG. 21, the horizontal axis represents the output voltage of the solar cell, and the vertical axis represents the output current of the solar cell. As shown in FIG. 21, the output characteristics of the solar cell vary greatly depending on the amount of solar radiation, and the output current width varies particularly greatly.

For example, when the electric power generated by the solar cell is used as commercial power, it is necessary to match the DC output power of the solar cell with the AC frequency and voltage of the commercial power. A device that performs this matching is called a connection matching device, but in order to keep the efficiency of matching in the connection matching device high, instead of directly inputting the output of the solar cell to the connection matching device, It is preferable to convert the input voltage and input current into a range in which the efficiency of the interconnection matching device can be kept high before inputting to the interconnection matching device. A circuit that performs this conversion is called a power conversion circuit. And it is preferable that a power converter circuit has high conversion efficiency in a wide input current area according to the output characteristic of a solar cell with a large fluctuation range.

In a power conversion circuit, in order to maintain high conversion efficiency for a wide input current range, high conversion efficiency is required even when the output current range is wide. When the output voltage is maintained at a constant value, it is possible to realize a power conversion circuit having high conversion efficiency in a predetermined range of output current, but power that maintains high conversion efficiency in a wide output current range. It is difficult to realize a conversion circuit. In the conventional power conversion circuit, when the output current is out of the predetermined range, the conversion efficiency of the power conversion circuit is lowered. In other words, when a large current is required as the output current, a power conversion circuit having high conversion efficiency may be used when the output current is a large current, but when a small current is output by the power conversion circuit, Conversion efficiency may be reduced.

In order to achieve high conversion efficiency for both large output current and small output current with a single power conversion circuit, the frequency and control method (PWM · PFM) in power conversion according to the range of output current ) And other control conditions are changed. For example, the circuit is controlled as PWM control with a constant frequency when the output current is large, and as PFM control with a constant ON width when the output current is small.

Further, Patent Document 1 discloses a power supply apparatus having a plurality of power conversion circuits having the same configuration and increasing or decreasing the number of circuits to be used according to the output current. In this power supply device, by combining a plurality of circuits, a power conversion circuit corresponding to the output current can be configured, and high conversion efficiency can be maintained in a wider output current region than when a single power conversion circuit is used. .

As described above, high conversion efficiency can be maintained in a certain range of output current by changing the frequency, control method (PWM / PFM), etc. in a single power conversion circuit. However, there is a limit to the range of the output current region, and it cannot be said that the range is sufficient to efficiently extract the output of the solar cell.

The power supply device of Patent Document 1 can widen the range of the output current region in which high conversion efficiency can be maintained by increasing the number of circuits to be combined, but the range is also limited, and the output of the solar cell is efficiently It's not enough to take it out. Since the power supply device of Patent Document 1 combines circuits having the same configuration, the number of required circuits is relatively large, and thus there is a problem that the power supply device is increased in size and cost. Further, in order to construct an optimum power conversion circuit in a wide output current range by combining circuits having the same configuration, there is a problem that the circuit design becomes complicated and the time required for the circuit design becomes long.

JP 2009-232587 A

An object of the present invention is to provide a power converter that has a wide input current range and an output current range, efficiently outputs power in response to fluctuations in input current over a wide range, and can be reduced in size and cost. Is to provide.

A power converter according to an embodiment of the present invention is a power converter that converts input power input as DC power and outputs the power, and is an integrated value over a predetermined time of the input current that is the current of the input power. An input current integration detection unit that repeatedly detects the input current integration value and a plurality of input current ranges that are different from each other and that overlap with adjacent input current ranges And a power conversion circuit unit selected from the plurality of power conversion circuit units based on the detected integrated input current value, and the most suitable for the selected power conversion circuit unit. And a power conversion control unit that performs control under a control condition that provides a large output power.

According to the power conversion device of one embodiment, it has a wide input current range and an output current range, and efficiently outputs power in response to fluctuations in the input current over a wide range, and can be reduced in size and cost. Is possible.

It is a block diagram which shows the structure of the solar energy power generation system using the power converter device which concerns on this embodiment. It is a block diagram which shows an example of a structure of the power converter device which concerns on this embodiment. It is explanatory drawing which made a part of example of a structure of the power converter device which concerns on this embodiment into the circuit diagram. It is a graph which shows the relationship between the input current and output power of each power inverter circuit unit of the power converter concerning this embodiment. It is a graph which shows the example of the relationship between the output current in a power converter circuit unit, and conversion efficiency. It is a figure which shows an example of the efficiency versus output current data regarding a 1st power converter circuit unit. It is a figure which shows an example of the efficiency versus output current data regarding the 2nd power inverter circuit unit. It is a figure which shows an example of the efficiency versus output current data regarding the 3rd power converter circuit unit. It is a flowchart which shows an example of the switching process of a power converter circuit unit. It is a flowchart which shows an example of the selection process of a power inverter circuit unit. 11 is a timing chart showing an example of switching of the power conversion circuit unit using the selection process of the flowchart of FIG. 10. It is a figure for demonstrating the difference of the output electric power with switching of a power converter circuit part, and without switching. It is a flowchart which shows another example of the selection process of a power inverter circuit unit. It is a timing chart which shows an example of the switching of the power converter circuit unit using the selection process of the flowchart of FIG. It is a flowchart which shows another example of the selection process of a power inverter circuit unit. 16 is a timing chart showing an example of switching of the power conversion circuit unit using the selection process of the flowchart of FIG. 15. It is a block diagram which shows an example of a structure of the power converter device which concerns on other embodiment. It is a flowchart which shows an example of the selection process of the power inverter circuit unit which concerns on other embodiment. It is a table which shows the relationship between the combination of the selection result by the input current integrated value and the selection result by the maximum input current, and the selected power conversion circuit unit. It is a flowchart which shows an example when one power converter circuit unit is selected based on the maximum current value. It is a graph which shows the example of the characteristic of a solar cell.

FIG. 1 is a block diagram showing a configuration of a photovoltaic power generation system using a power conversion device according to the present embodiment. As shown in FIG. 1, a photovoltaic power generation system used in conjunction with a commercial power system can be realized using the power conversion device 100 and the solar battery PV according to this embodiment. In this solar power generation system, the solar cell PV, the power conversion device 100 connected to the solar cell PV, the output converted by the power conversion device 100 is further transformed, or the DC-AC conversion is performed. An interconnection matching device 200 for matching with the commercial power system is provided, and the interconnection matching device 200 is connected to the commercial power system.

The solar cell PV generates power according to the amount of solar radiation and outputs power.

The power conversion device 100 converts the input power with high conversion efficiency and outputs it. Details of the power conversion apparatus 100 will be described later.

The interconnection matching device 200 includes, for example, a DC-AC inverter circuit, and converts the output from the power conversion device 100 into an AC voltage of about 100V or about 200V of commercial power so that the output can be transmitted to the commercial power system.

The power output from the solar cell PV generated by the incidence of sunlight is input to the power conversion device 100. In the power converter 100, the output from the solar cell PV is used as input, and the power is converted with high conversion efficiency regardless of the range of the input current value. The power converted by the power conversion device 100 is input to the interconnection matching device 200, appropriately converted so as to be transmitted through the commercial power system, and transmitted to the commercial power system. Thus, the output from the solar cell PV can be sold effectively.

In addition, the input side of the power converter 100 can be connected to the solar battery PV, the output side can be connected to the storage battery, and the power generated by the solar battery PV can be stored in the storage battery.

By using the power conversion device 100 according to the present embodiment, it is possible to configure a solar power generation system that can extract the output from the solar cell PV with high conversion efficiency. A power conversion apparatus 100 according to the present embodiment will be described with reference to the drawings.

FIG. 2 is a block diagram showing an example of the configuration of the power conversion apparatus according to this embodiment. FIG. 3 is an explanatory diagram in which a part of an example of the configuration of the power conversion device according to this embodiment is a circuit diagram, and a solar cell PV is connected to the power conversion device 100.

As illustrated in FIG. 2, the power conversion apparatus 100 includes a power conversion control unit 1, an input current detection unit 2 that detects an input current Iin that is a current of the input power Pin, and an input voltage Vin that is a voltage of the input power Pin. An input voltage detection unit 3 that detects power, a first power conversion circuit unit 4 that performs power conversion, a second power conversion circuit unit 5 and a third power conversion circuit unit 6, and an output current Iout that is a current of the output power Pout. An output current detection unit 7 for detecting, an output voltage detection unit 8 for detecting an output voltage Vout which is a voltage of the output power Pout, an alarm output unit 9 for outputting an alarm signal, and an input current integration detection unit 10 are provided. Yes.

The first to third power conversion circuit units 4 to 6 are circuits each configured to convert and output input power, and these have different input current ranges. The first to third power conversion circuit units 4 to 6 receive the power input to the power conversion apparatus 100, and the input is controlled by the power conversion control unit 1.

As shown in FIG. 3, the first to third power conversion circuit units 4 to 6 are switching elements FET1, FET2, and FET3, commutation diodes D1, D2, and D3, and inductors for storing energy during power conversion. A certain coil (reactor) L1, L2, L3 and capacitors C1, C2, C3 are provided.

All of the switching elements FET1 to FET3 may be MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors: metal-oxide-semiconductor field effect transistors). The commutation diodes D1 to D3 may be ordinary diodes or Zener diodes. The first to third power conversion circuit units 4 to 6 constitute a step-down DC / DC converter.

The gates of the switching elements FET1 to FET3 are respectively connected to the power conversion control unit 1, and are controlled to be turned on and off by drive signals S1 to 3 transmitted from the power conversion control unit 1. The power conversion control unit 1 can select which of the first to third power conversion circuit units 4 to 6 is used to convert the output of the solar cell PV, and the power conversion control unit 1 further selects the first Each of the 3 to 3 power conversion circuit units 4 to 6 is controlled.

In the first to third power conversion circuit units 4 to 6, the inductances of the coils L1 to L3 have different values, and the values of the output power with respect to the input current are different from each other.

The relationship between the input current Iin and the output power Pout of the first to third power conversion circuit units 4 to 6 will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the input current and the output power of each power conversion circuit unit of the power conversion apparatus according to this embodiment.

As shown in FIG. 4, the first to third power conversion circuit units 4 to 6 have different characteristics of the output power Pout with respect to the input current Iin. The value of the input current Iin when obtaining the peak output power in each of the first to third power conversion circuit units 4 to 6 is also different from each other in each power conversion circuit unit.

The input current ranges of the first to third power conversion circuit units 4 to 6 are different from each other and have a portion overlapping with the adjacent input current range. That is, as shown in FIG. 4, the input current ranges of the first power conversion circuit unit 4 and the second power conversion circuit unit 5 are adjacent to each other, and these current ranges are overlapped (in FIG. 4, a broken line). (See the part shown in). Similarly, the input current ranges of the second power conversion circuit unit 5 and the third power conversion circuit unit 6 are adjacent to each other, and these current ranges overlap (see the portion indicated by the broken line in FIG. 4).

When power conversion is performed using any one of the first to third power conversion circuit units 4 to 6, the boundary of the input current Iin of each power conversion circuit unit that can obtain the largest output power Pout is The threshold values th1 and th2, which are located on the small current side, are defined as the small current side threshold value th1, and those located on the large current side are defined as the large current side threshold value th2.

When the input current Iin is smaller than the small current side threshold th1, it is preferable to perform power conversion by the first power conversion circuit unit 4, and when the input current Iin is not less than the small current side threshold th1 and the large current side threshold is reached. When it is smaller than the value th2, it is preferable to perform power conversion by the second power conversion circuit unit 5, and when the input current Iin is greater than or equal to the large current side threshold th2, the third power conversion circuit unit 6 performs power conversion. Preferably it is done.

The conversion efficiency of the first to third power conversion circuit units 4 to 6 varies depending on the values of the input current Iin and the output current Iout. In particular, the level of conversion efficiency is determined by the inductance and DC resistance of the coils L1-3. FIG. 5 is a graph showing an example of the relationship between the output current and the conversion efficiency in the power conversion circuit unit. FIG. 5A is a graph related to a power conversion circuit unit that is preferable when the output current Iout is relatively large, and FIG. 5B is a graph related to a power conversion circuit unit that is preferable when the output current Iout is relatively small. The conversion efficiency η is the ratio of the output power Pout to the input power Pin, and it can be said that the conversion efficiency η is a power conversion unit capable of performing power conversion with higher efficiency as the conversion efficiency η increases.

Each of the power conversion circuit units used in FIGS. 5A and 5B is a power conversion circuit unit having a circuit configuration similar to that of the first to third power conversion circuit units 4 to 6, The coils have different inductances.

5A operates under the conditions of an input voltage of 120 V, an output voltage of 100 V, and an output current of about 0.2 A to 10 A, and can obtain the highest conversion efficiency η when the input current is around 10 A. Designed to be able to. A coil capable of outputting a large current is selected for the power conversion circuit unit. Generally, a large current type coil has a comparatively small L value of 0.1 μH to several μH, and PWM switching control at a high frequency of 300 KHz to 1 MHz can realize a conversion efficiency of 90% or more when the output current is around 10 A. . However, when the output current is 1 A or less, the self-circuit loss is large, so that the conversion efficiency η is reduced to about 50%.

The power conversion circuit unit in FIG. 5B operates under conditions of an input voltage of 120 V, an output voltage of 100 V, and an output current of about 0 A to 1 A so that the highest conversion efficiency η can be obtained when the input current is around 1 A. Designed. A coil capable of outputting a small current is selected for the power conversion circuit unit. Generally, a small current type coil has an L value of several tens of μH to several hundred μH, and PWM switching control is performed at a relatively low frequency of 300 KHz or less, so that the conversion efficiency is 90% in a current range of about 0.01 A to 1 A. Front and back can be realized. However, when the output current exceeds 1 A, the output decreases and a large current cannot be output.

The first to third power conversion circuit units 4 to 6 perform power conversion with high conversion efficiency in different input current ranges, and are scheduled to be input to the power conversion device 100 depending on the input current ranges. The input current range can be covered.

The first to third power conversion circuit units 4 to 6 are not limited to the circuit configuration shown in FIG. 3 as long as the converters have different input current ranges in which high conversion efficiency can be obtained. . What is necessary is just to design according to the intended purpose of the power converter device 100, respectively. For example, a bipolar transistor may be used as the switching element instead of the MOSFET. Also, a power conversion circuit unit that operates in the same manner as the first to third power conversion circuit units 4 to 6 can be configured by using a switching element such as a MOSFET or a bipolar transistor instead of the commutation diode and using a synchronous rectification type. Can do.

Also, a power conversion circuit unit having a configuration different from that of the first to third power conversion circuit units 4 to 6 may be used. For example, a boost type or a step-up / down type may be used. Further, the number of power conversion circuit units is not limited to three as long as it is plural. The circuit configuration and the number of the power conversion circuit units may be appropriately adjusted according to the input current range of the power conversion device 100 determined according to the output of the power source connected to the power conversion device 100 and the like.

The input current detection unit 2 detects the value of the input current Iin as needed and transmits it to the power conversion control unit 1. The input current detection unit 2 is configured using, for example, a current detection resistor, has an A / D converter, converts an analog signal detection value into a digital signal, and transmits the digital signal to the power conversion control unit 1.

The input voltage detection unit 3 detects the value of the input voltage Vin as needed and transmits it to the power conversion control unit 1. The input voltage detection unit 3 is configured using, for example, a voltage dividing resistor, has an A / D converter, converts an analog signal detection value into a digital signal, and transmits the digital signal to the power conversion control unit 1.

The input current integration detection unit 10 detects the integrated value of the input current Iin every predetermined time and transmits it to the power conversion control unit 1. The input current integration detection unit 10 is configured using, for example, a current detection resistor, has an A / D converter, converts an analog signal detection value into a digital signal, and transmits the digital signal to the power conversion control unit 1. .

In addition, without providing the input current integration detection unit 10, the detected value of the input current detected by the input current detection unit 2, converted into a digital signal and transmitted to the power conversion control unit 1 is used as the power conversion control unit 1. The integrated value of the input current Iin may be calculated by integrating with a later-described CPU or the like.

The output current detection unit 7 detects the value of the output current Iout as needed and transmits it to the power conversion control unit 1. The output current detection unit 7 is configured using, for example, a resistor for current detection, has an A / D converter, converts the detected value of the analog signal into a digital signal, and transmits the digital signal to the power conversion control unit 1.

The output voltage detection unit 8 detects the value of the output voltage Vout as needed and transmits it to the power conversion control unit 1. The output voltage detection unit 8 is configured using, for example, a voltage dividing resistor, and has an A / D converter. The output voltage detection unit 8 converts an analog signal detection value into a digital signal and transmits the digital signal to the power conversion control unit 1.

2, the power conversion control unit 1 includes an efficiency versus output current data storage unit 12, an optimum integrated value range storage unit 13, a selection unit 14, and a control condition determination unit 15. The power conversion control unit 1 can be configured using, for example, a CPU, a nonvolatile memory, a RAM, and the like. The power conversion control unit 1 selects one power conversion circuit unit from the first to third power conversion circuit units 4 to 6 based on the integrated value of the input current Iin detected by the input current integration detection unit 10. The power conversion circuit unit is controlled under control conditions such that the selected power conversion circuit unit can obtain the largest output power Pout.

The efficiency versus output current data storage unit 11 is, for example, a nonvolatile memory, and stores efficiency versus output current data TD1 to TD3 as shown in FIGS. The efficiency versus output current data TD1 to TD3 is data obtained by measurement in advance for each of the first to third power conversion circuit units 4 to 6, and the conversion efficiency in each of the first to third power conversion circuit units 4 to 6 It is data which shows the relationship between (eta) and output current Iout. The efficiency versus output current data TD1 to TD3 are graphs showing the relationship between the conversion efficiency η and the output current Iout, which are in the form of a table with the input current Iin and the output voltage Vout as parameters as shown in FIGS. Can be represented. 6 to 8 are diagrams showing examples of efficiency versus output current data regarding the first to third power conversion circuit units 4 to 6, respectively.

The efficiency vs. output current data TD1 to TD3 are data for each input current Iin and for each output voltage Vout in each power conversion circuit unit. For example, the input current Iin is selected in 5A increments of 2A in the range of 1A to 9A, The output voltage is 80 to 120V, and 5 points are selected in increments of 10V. As shown in FIGS. 6 to 8, the efficiency versus output current data TD1 to TD3 is data in a table format divided by the input current Iin and the output voltage Vout.

The range of the input current Iin in the efficiency vs. output current data TD1 to TD3 is the range of the input current Iin that is actually planned to be used in the power converter 100. The range of the output voltage Vout in the efficiency versus output current data TD1 to TD3 is the range of the output voltage Vout that is actually planned to be used in the power conversion apparatus 100. In these ranges, it can be said that the more the plurality of graphs, the more accurate power conversion can be performed. When the efficiency vs. output current data TD1 to TD3 is obtained by measurement, the amount of the efficiency vs. output current data TD1 to TD3 is increased by making the step of the input current Iin and the step of the output voltage Vout smaller. Therefore, more accurate power conversion is possible.

The optimal integrated value range storage unit 13 is, for example, a nonvolatile memory, and stores the optimal integrated value range corresponding to each power conversion circuit unit. The optimum integrated value range is a range set for each power conversion circuit unit, and the power conversion circuit unit corresponding to the optimum integrated value range including the input current integrated value Iint that is an integrated value of the input current Iin Conversion is preferable in terms of conversion efficiency η.

The optimum integrated value ranges respectively corresponding to the first power conversion circuit unit 4, the second power conversion circuit unit 5, and the third power conversion circuit unit 6 are a first optimum integrated value range, a second optimum integrated value range, and a third optimum integrated value range, respectively. It is the optimum integrated value range. The power conversion device 100 of the present embodiment maintains a high conversion efficiency η by switching the power conversion circuit unit according to which optimum integrated value range the input current integrated value Iint is included in.

When there are three power conversion circuit units as in the present embodiment, it is preferable to select the first power conversion circuit unit 4 when the input current integrated value Iint is within the first optimum integrated value range. When the input current integrated value Iint is within the second optimum integrated value range, the second power conversion circuit unit 5 is preferably selected. When the input current integrated value Iint is larger than the second optimum integrated value range, the third power conversion circuit unit 6 may be selected. Therefore, the third optimum integrated value range need not be stored. Good. These optimum integrated value ranges may be obtained in advance by measurement and stored in the optimum integrated value range storage unit 13.

Furthermore, only the second optimum integrated value range is stored, and when the input current integrated value Iint is equal to or less than the second optimum integrated value range, the first power conversion circuit unit 4 is selected, and the input current integrated value Iint is the first When the input current integrated value Iint is larger than the second optimum integrated value range, the third power conversion circuit unit 6 is selected when the input current integrated value Iint is larger than the second optimum integrated value range. May be.

The selection unit 14 compares the input current integration value Iint detected by the input current integration detection unit 10 with the optimum integration value range stored in the optimum integration value range storage unit 13 and includes the input current integration value Iint. The optimum integrated value range is obtained, and one power conversion circuit unit corresponding to the optimum integrated value range is selected.

The control condition determination unit 15 obtains the highest conversion efficiency η when operating the selected power conversion circuit unit based on the efficiency versus output current data TD1 to TD3 stored in the efficiency versus output current data storage unit 12. The output voltage Vout that can be obtained is acquired, and the acquired output voltage Vout is set as a target value of the output voltage Vout. The target value of the output voltage Vout is the output voltage Vout when the largest output power Pout is obtained in the selected power conversion circuit unit.

The alarm output unit 9 receives the signal from the power conversion control unit 1 and outputs an alarm signal to notify the operator that an abnormality has occurred in the operation of the power conversion device 100. The alarm output unit 9 is a buzzer for notifying the operator of an abnormality by sounding an alarm sound, an alarm lamp (lamp) for notifying the operator of an abnormality by lighting or flashing, and displaying characters or the like on the display screen indicating the abnormality. Thus, a display device or the like that informs the operator may be used.

Next, the operation of the power conversion apparatus 100 will be described. In the solar power generation system shown in FIG. 1, the power generated by the solar cell PV is input to the power conversion device 100. In the power conversion device 100, the power conversion control unit 1 selects from the first to third power conversion circuit units 4 to 6 every time a predetermined time (integrated time) for detecting the input current integrated value Iint elapses. Processing (selection processing) for selecting one power conversion circuit unit that can obtain preferable output power is performed. The input current integration detection unit 10 detects the integrated value of the input current over this integration time, and the selection unit 14 selects the power conversion circuit unit based on this detection value. For example, the integration time may be about several tens of seconds to several minutes. Preferably it is about 30 seconds.

The power conversion control unit 1 obtains a control condition for obtaining the maximum output power when PWM (Pulse Width Modulation) switching control is performed on the selected power conversion circuit unit, and is selected according to the control condition. Only one power conversion circuit unit is controlled. The control conditions include switching frequency, output voltage target value Vm, ON-OFF duty ratio, and the like.

When the selected power conversion circuit unit is a power conversion circuit unit currently used, the power conversion control unit 1 continues to control the power conversion circuit unit so as to obtain the largest output power Pout. Continue. However, when the newly selected power conversion circuit unit is different from the power conversion circuit unit currently used, the power conversion control unit 1 inputs the input power Pin to the selected power conversion circuit unit. In this way, the selected power conversion circuit unit is controlled.

The operation of the power conversion apparatus 100 will be specifically described with reference to FIGS. 9 and 10. FIG. 9 is a flowchart illustrating an example of the switching process of the power conversion circuit unit, and FIG. 10 is a flowchart illustrating an example of the selection process of the power conversion circuit unit.

As shown in FIG. 9, the power conversion control unit 1 determines whether or not the power conversion circuit unit needs to be switched every predetermined time (for example, 30 seconds) (# 11). This predetermined time is equal to the integrated time of the input current integrated value Iint. When the power conversion control unit 1 selects a power conversion circuit unit different from the power conversion circuit unit currently used based on the result of the selection process of the power conversion circuit unit described later, the power conversion circuit unit Switching is necessary (Yes in # 11).

The switching of the power conversion circuit unit is performed by the drive signals S1 to S3 of the power conversion control unit 1. For example, assuming that the first power conversion circuit unit 4 is currently selected, the drive signal S2 and the drive signal S3 are OFF, and only the drive signal S1 is transmitted. The drive signal S1 is a signal for the first power conversion circuit unit 4 to perform PWM switching control, and is a signal that repeats ON and OFF at a constant cycle. Since the drive signal S2 and the drive signal S3 are OFF, the input power Pin is not input to the second power conversion circuit unit 5 and the third power conversion circuit unit 6. Input power Pin is input only to the first power conversion circuit unit 4, and output power Pout is output.

If the second power conversion circuit unit 5 is selected in the selection process, the power conversion control unit 1 turns off the drive signal S1 and transmits only the drive signal S2. Since the drive signal S1 and the drive signal S3 are OFF, the input power Pin is not input to the first power conversion circuit unit 4 and the third power conversion circuit unit 6. Input power Pin is input only to the second power conversion circuit unit 5, and output power Pout is output. In this way, the power conversion circuit unit is switched.

The power conversion control unit 1 sets the target value of the output voltage Vout of the second power conversion circuit unit 5 instead of the first power conversion circuit unit 4 (# 12). As described above, the target value of the output voltage Vout is the output voltage Vout when the largest output power Pout is obtained in the selected power conversion circuit unit. The target value of the output voltage Vout is obtained in the selection process. Setting the target value of the output voltage Vout means controlling the power conversion circuit unit so that the target value of the output voltage Vout is obtained.

The switching frequency and the duty ratio at which the power conversion control unit 1 can obtain the target value of the output voltage Vout in the PWM switching control when the input current Iin flows to the second power conversion circuit unit 5 are as follows: It is required in the selection process. The power conversion control unit 1 transmits the drive signal S2, and controls the second power conversion circuit unit 5 according to the obtained control conditions (switching frequency and duty ratio). Accordingly, the second power conversion circuit unit 5 outputs the output voltage Vout around the target value of the output voltage Vout, and the largest output power Pout is obtained.

The detected value of the output voltage Vout detected by the output voltage detector 8 and the target value of the output voltage Vout are compared by the power conversion controller 1 (# 13). In the case of No in # 11, power conversion may be performed by the currently selected first power conversion circuit unit 4, and thus the process proceeds to # 13 without performing # 12. In # 13, based on the comparison result, the power conversion control unit 1 adjusts the duty ratio by feedback control so that the detected value of the detected output voltage Vout and the target value of the output voltage Vout are matched ( # 14).

After the duty ratio is adjusted, the power conversion control unit 1 determines whether it is necessary to reset the target value of the output voltage Vout (# 15). Specifically, the power conversion control unit 1 compares the detected value of the current input current Iin with the detected value of the input current Iin used when obtaining the target value of the output voltage Vout. If these values are different and the difference is greater than or equal to a predetermined value set in advance, it is determined that it is necessary to reset the target value of the output voltage Vout (Yes in # 15). This is because it is considered that the target value of the output voltage Vout may have changed significantly compared to the value when the second power conversion circuit unit 5 is selected.

The target value of the output voltage Vout is again acquired and reset by the power conversion control unit 1 based on the efficiency versus output current data TD2 of the second power conversion circuit unit 5 shown in FIG. 7 (# 16). That is, when the current detection value of the input current Iin is input to the second power conversion circuit unit 5, the power conversion control unit 1 can obtain the target value of the output voltage Vout acquired again by PWM switching control. A switching frequency and a duty ratio that can be calculated are calculated, and the second power conversion circuit unit 5 is controlled based on the control conditions.

When it is not necessary to reset the target value of the output voltage Vout (No in # 15) and after resetting the target value of the output voltage Vout (# 16), the process returns to # 11 and the above steps are repeated.

In FIG. 9, the power conversion circuit unit is automatically controlled by feedback. For example, when the operation of the power conversion circuit unit is terminated because power generation by the solar cell PV cannot be performed due to sunset or the like, for example, the output current from the input current detection unit 2 is set to a predetermined value in the power conversion control unit 1. What is necessary is just to have a function of detecting the following state and terminating the loop of FIG. 9 by interrupt processing or the like.

The selection process for selecting one power conversion circuit unit will be described with reference to FIG. The selection process is performed prior to the step # 11 of FIG. The input current integration detection unit 10 detects the input current integration value Iint for each integration time (# 21). The input current integrated value Iint is obtained by integrating the input current Iin over time. Every time the integration time elapses, the input current integration value Iint is detected. When the input current integration value Iint is detected, the detection value in the input current integration detection unit 10 is reset, and the input current integration value Iint again becomes zero. Integration of the input current Iin is started.

The selection unit 14 determines whether or not the detected input current integrated value Iint is included in the first optimal integrated value range stored in the optimal integrated value range storage unit 13 (# 22). When the detected input current integrated value Iint is included in the first optimal integrated value range (Yes in # 22), the first power conversion circuit unit 4 is selected by the selection unit 14 (# 23).

If the detected input current integrated value Iint is not included in the first optimal integrated value range (No in # 22), the selection unit 14 causes the detected input current integrated value Iint to be stored in the optimal integrated range storage unit 13. It is determined whether it is included within the stored second optimum integrated value range (# 24). When the detected input current integrated value Iint is included in the second optimum integrated value range (Yes in # 24), the second power conversion circuit unit 5 is selected by the selection unit 14 (# 25).

When the detected input current integrated value Iint is not included in the second optimal integrated value range (No in # 24), the selection unit 14 selects the third power conversion circuit unit 6 (# 26).

In each of the steps # 23, # 25, and # 26, after the first to third power conversion circuit units 4 to 6 are selected, the control condition determination unit 15 selects the largest power conversion circuit unit. Control conditions (duty ratio, target value of output voltage Vout, switching frequency, etc.) for obtaining output power are determined (# 27). Then, the process proceeds to step # 11 in FIG.

The method for determining the target value of the output voltage Vout in the selected power conversion circuit unit in the control condition determination unit 15 will be specifically described.

Suppose that the second power conversion circuit unit 5 is selected in the selection unit 14, the detected value of the input current Iin is 5A, and the range that the output voltage can take is 80 to 120V. The range that the output voltage Vout can take is a value that is determined according to the output of the power source connected to the power conversion apparatus 100, and the range of the output voltage Vout used in the power conversion apparatus 100. The control condition determining unit 15 extracts five data of 80V, 90V, 100V, 110V, and 120V in the 5A row from the efficiency versus output current data TD2 shown in FIG.

Among these data, select the data that maximizes the conversion efficiency η within the possible range of the output current Iout. The range that the output current Iout can take is a value determined according to the output of the power source connected to the power conversion device 100, and the range of the output current Iout used in the power conversion device 100. If the output current Iout when the conversion efficiency η is maximum is obtained, the target value of the output voltage Vout is obtained from that value.

The input power Pin is calculated by multiplying the detected input current Iin (5 A) and each input voltage Vin (Iin × Vin = Pin). If the input voltage Vin is fixed, the value may be used without detection, and if the input voltage Vin varies, the value detected by the input voltage detector 3 may be used. By multiplying the calculated input power Pin by the selected maximum conversion efficiency η, the largest output power Pout in the second power conversion circuit unit 5 is calculated (Pin × η = Pout). By dividing this Pout by Iout that maximizes the conversion efficiency η, the target value of the output voltage Vout can be obtained (Pout / Iout = Vout).

The power conversion control unit 1 does not store the efficiency versus output current data TD1 to TD3, and obtains the maximum output power Pout with respect to the input current Iin in the first to third power conversion circuit units 4 to 6 by measurement in advance. In addition, these values may be stored. In that case, the power conversion control unit 1 can obtain the maximum output power Pout in the selected power conversion circuit unit based on the detected value of the input current Iin, and further output the output power Pout based on the detected value of the output current Iout. A target value of the voltage Vout can be obtained.

Further, the maximum output power Pout with respect to the input current Iin, the target value of the output voltage Vout at that time, the duty ratio, and the switching frequency are also obtained in advance by measurement, and the power conversion control unit 1 stores these values. It is good to be.

In the power conversion apparatus 100, the PWM switching control is used for the control of the first to third power conversion circuit units 4 to 6. However, it is sufficient that the power conversion can be performed, and other control methods such as PFM control may be used. Good. Further, when the input voltage Vin is a fixed value, the input voltage detection unit 3 may not be provided. However, by providing the input voltage detection unit 3 and detecting the input voltage Vin, a more accurate value can be used. And high-precision control is possible.

Also, if the change in the input voltage Vin is large, there may be some abnormality. The power conversion control unit 1 calculates the fluctuation range per predetermined time of the input voltage Vin detected by the input voltage detection unit 3 and compares it with a predetermined set value stored in advance. A signal may be transmitted to the alarm output unit 9, and the alarm output unit 9 outputs an alarm signal to notify the operator. For example, the lamp may be turned on, an alarm sound may be generated, or a warning display may be displayed on the display screen.

Further, the power conversion control unit 1 calculates the output power Pout as needed by multiplying the output current Iout detected by the output current detection unit 7 and the output voltage Vout detected by the output voltage detection unit 8. A signal may be transmitted to the alarm output unit 9 when the value of the output power Pout becomes smaller than a predetermined value set in advance.

Switching of the power conversion circuit unit in the power conversion device 100 will be described with reference to FIG. FIG. 11 is a timing chart showing an example of switching of the power conversion circuit unit using the selection process of the flowchart of FIG.

In FIG. 11, the upper part is a diagram showing the relationship between the input current integrated value Iint and time, and the lower part is a power conversion circuit unit that is selected when the input current integrated value Iint changes with time as shown in the upper part. FIG. In FIG. 11, a case where the two power conversion circuit units of the first power conversion circuit unit 4 and the second power conversion circuit unit 5 are switched will be described in order to simplify the description.

In FIG. 11, the first optimum integrated value range is 0 or more and I1 or less. The second optimum integrated value range is greater than I1 and less than or equal to I2.

In the upper and lower stages, the horizontal axis indicates the time, and numbers are added to the integration time intervals for detecting the input current integration value Iint. The input current Iin is integrated between adjacent numbers (integrated time) to detect the input current integrated value Iint, which is used for selection of the power conversion circuit unit. When the input current integrated value Iint used for selection is detected, the input current integrated value Iint is once reset to 0 and the input current integrated value Iint is detected again. In FIG. 11, the input current integrated value Iint increases with time. However, the input current integrated value Iint may be detected at each integration time (at each timing indicated with a number), and the input current integrated value Iint is continuously calculated. It does not continue to measure.

In the following description, the number “0” to the number “1” indicated on the horizontal axis is the first period, the number “1” to the number “2” is the second period, and the number “2”. To the number “3” is described as the third cycle.

In the first cycle, the input current integrated value Iint exceeds I1 and is included in the second optimum integrated value range. Therefore, since the second power conversion circuit unit 5 is selected by the power conversion control unit 1, the power conversion circuit unit is switched.

Also in the second cycle, since the input current integrated value Iint is included in the second optimum integrated value range, the power conversion control unit 1 selects the second power conversion circuit unit 5.

In the third period, since the input current integrated value Iint is equal to or less than I1, it is included in the first optimum integrated value range. Therefore, since the first power conversion circuit unit 4 is selected by the power conversion control unit 1, the power conversion circuit unit is switched.

Also in the fourth period, since the input current integrated value Iint is included in the first optimum integrated value range, the power conversion control unit 1 selects the first power conversion circuit unit 4.

In the fifth cycle, since the input current integrated value Iint is included in the second optimum integrated value range, the power conversion control unit 1 selects the second power conversion circuit unit 5, so that the power conversion circuit unit is switched.

In the sixth period, since the input current integrated value Iint is included in the first optimum integrated value range, the first power conversion circuit unit 4 is selected by the power conversion control unit 1, so that the power conversion circuit unit is switched.

In the seventh to ninth cycles, since the input current integrated value Iint is included in the first optimum integrated value range, the power conversion control unit 1 selects the first power conversion circuit unit 4.

In the tenth cycle, since the input current integrated value Iint is included in the second optimum integrated value range, the second power conversion circuit unit 5 is selected by the power conversion control unit 1, so that the power conversion circuit unit is switched.

In the eleventh cycle, the input current integrated value Iint is included in the second optimum integrated value range, so the power conversion control unit 1 selects the second power conversion circuit unit 5.

In this embodiment, the integrated value of the input current Iin over the integrated time (input current integrated value Iint) is repeatedly detected, and a preferred power conversion circuit unit is selected based on this value. Thus, a preferred power conversion circuit unit is selected from the plurality of first to third power conversion circuit units 4 to 6, and power conversion is performed by the power conversion circuit unit. Therefore, the current value range of the input current Iin Can maintain a high conversion efficiency .eta.

In addition, the selection process, which is a determination as to which of the first to third power conversion circuit units 4 to 6 is selected, is performed every integration time in which the input current integration value Iint is detected. Since the number of times of selection processing is reduced as compared with the case where selection processing of the power conversion circuit unit is performed at any time according to the change in the value of, the number of switching of the power conversion circuit unit is reduced. For this reason, loss caused by switching the power conversion circuit portion hardly occurs, and power loss is low.

As a loss caused by switching the power conversion circuit unit, there is a power loss consumed by the power conversion control unit 1 in the selection process. The first to third power conversion circuit units 4 to 6 also lose when starting and stopping. For example, when the input to the operating power conversion circuit unit stops due to switching, there is power already stored in the circuit unit, and a loss related to the power occurs. In addition, in the power conversion circuit unit that has started to operate by switching, at the moment of switching, high conversion efficiency η is not realized and loss occurs.

When the selection process of the power conversion circuit unit is performed at any time according to the change in the value of the input current Iin, a preferable power conversion circuit unit can be selected according to the change in the input current Iin. Although a high conversion efficiency η is realized, a loss is caused by switching the first to third power conversion circuit units 4 to 6 at any time following the conversion of the input current Iin. If the switching is performed too frequently, the loss becomes high, and the efficiency of the power converter as a whole decreases.

Especially, the output of the solar cell PV is not smooth, and there is a high possibility that it constantly fluctuates in a minute range. That is, since the input current Iin of the power conversion device also constantly fluctuates, if the input current Iin is located near the switching boundary of the power conversion circuit unit, the power fluctuations even if there is no significant fluctuation of the input current There is a high possibility that the circuit part is frequently switched. In such a case, the loss due to switching increases, and the power from the solar cell PV cannot be taken out efficiently.

As in this embodiment, switching the power conversion circuit unit based on the integrated input current value Iint eliminates unnecessary switching of the power conversion circuit unit and maintains a high conversion efficiency η.

The difference in output power in the power conversion circuit unit between when the power conversion circuit unit is switched and when switching is not described with reference to FIG. FIG. 12 is a diagram for explaining the difference in output power between when the power conversion circuit unit is switched and when there is no switching. In FIG. 12, the vertical axis represents the output power of the power conversion circuit unit, and the horizontal axis represents time. The case where switching is performed using the first power conversion circuit unit 4 and the second power conversion circuit unit 5 is shown.

In FIG. 12, the change in output power when switching is shown by a solid line. In order to simplify the description, it is assumed that the cycle in which the first power conversion circuit unit 4 and the second power conversion circuit unit 5 are switched is constant, and the cycle is T. If the output power is 80 W or less, the conversion efficiency is high when power conversion is performed using the first power conversion circuit unit 4. If the output power is greater than 80 W, the power conversion is performed using the second power conversion circuit unit 5. If conversion is performed, the conversion efficiency is assumed to be high. In order to simplify the description, the power conversion circuit unit is selected based on the output power, but the same applies if the power conversion circuit unit is selected based on the input current Iin. A change in output power when the power conversion is performed using the second power conversion circuit unit 5 without switching is shown by a broken line.

When switching the power conversion circuit unit, the first power conversion circuit unit 4 is used when the output power is 80 W or less, and when the output power is greater than 80 W, the second power conversion circuit unit 5 is used. When the power conversion circuit unit is not switched, the second power conversion circuit unit 5 is used regardless of the value of the output power.

When the output power is larger than 80 W, both use the second power conversion circuit unit 5, so the characteristics are equal. In the case of 80 W or less, the output power is reduced by ΔP when switching is not performed. This is because the conversion efficiency η is lowered by using the second power conversion unit 5 in a range where it is preferable to use the first power conversion unit 4. However, it is preferable not to switch the power conversion circuit unit if the loss due to switching the power conversion circuit unit is larger than the decrease in output power due to ΔP.

When it is preferable to use the first power conversion circuit unit 4 when the power consumption amount (Pchg), the number of switching times (N), and the first power conversion circuit unit 4 are preferably used for switching the power conversion circuit unit Using the difference (ΔP) between the output power and the output power when the first power conversion circuit unit 4 is used and the time (T) when the first power conversion circuit unit 4 is preferably used, When the relationship expressed is satisfied, it is preferable not to switch. N is switched from the first power conversion circuit unit 4 to the second power conversion circuit unit 5 and switched to the first power conversion circuit unit 4 again, or from the second power conversion circuit unit 5 to the first power. When switching to the conversion circuit unit 4 and switching to the second power conversion circuit unit 5 again, it is assumed to be once each.

Pchg × 2 × N> ΔP × T
Using this equation, it can be determined whether it is preferable to use a case where switching is not performed or a case where switching is performed.

In addition, when using a power conversion circuit unit having a different current range, a power conversion circuit on the large current side is compared to using a power conversion circuit unit on the small current side, that is, a power conversion circuit unit with a small input current range, at a large current. The loss is lower when the power converter circuit portion having a large input current range is used with a small current. Therefore, in the example described with reference to FIG. 12 above, when power conversion is performed using the first power conversion circuit unit 4 regardless of the output power (no switching), ΔP increases, which is not preferable. .

In the power conversion device 100 of the present embodiment, the power conversion circuit unit is selected based on the integrated input current value Iint, and power conversion is performed using the power conversion circuit unit. Therefore, even when the range of the input current Iin is wide Thus, power conversion having high conversion efficiency η can be performed over the entire range. Furthermore, it is possible to suppress the number of switching of the power conversion circuit unit, suppress unnecessary switching, and reduce loss caused by switching. Thereby, efficient power conversion can be performed.

In the example described above, the power conversion device 100 that selects the power conversion circuit unit using the detected input current integrated value Iint for each integration time for detecting the input current integrated value Iint has been described. In addition, for example, the input current integrated value Iint may be detected a plurality of times, and the power conversion circuit unit may be selected when the value is continuously included in the same optimum integrated value range for a predetermined number of times. As a result, even when the input current Iin varies in a wide range, it is possible to perform power conversion using a more preferable power conversion circuit unit and to suppress the number of switching of the power conversion circuit.

The configuration of the power conversion apparatus 100 in this case is the same as that described above, but the operation of the selection unit 14 in the selection process is slightly different. The selection unit 14 has a predetermined number of times determined in each optimum integrated value range, and the input current integrated value Iint is continuously included in the same optimal integrated value range by the predetermined number of times (selection set number). In this case, the selection unit 14 selects a power conversion circuit unit corresponding to the optimum integrated value range.

More specifically, the selection unit 14 compares the input current integration value Iint detected by the input current integration detection unit 10 with the optimum integration value range stored in the optimum integration value range storage unit 13, and inputs An optimum integrated value range including the current integrated value Iint is obtained. The selection unit 14 does not select the power conversion circuit unit based on only this result, but waits for the input current integration detection unit 10 to detect the next input current integration value Iint. In this way, the selection unit 14 repeatedly waits for the input current integrated value Iint to be detected, and determines each time within which optimum integrated value range the input current integrated value Iint is included. The selection unit 14 waits until it can be determined that the input current integrated value Iint is continuously included in the same optimal integrated value range, and that the number of times is the number of times of selection and setting of the optimal integrated value range. If it can be determined, the power conversion circuit unit corresponding to the optimum integrated value range is selected.

It should be noted that the number of times of selection setting may be plural, and the first to third power conversion circuit units 4 to 6 may be different from each other. As described above, when using a power conversion circuit unit having a different current range, the loss is greater when the power conversion circuit unit on the large current side is used with a small current than when the power conversion circuit unit on the small current side is used with a large current. Few. When the input current Iin is near the boundary for switching the power conversion unit, it is preferable to use the power conversion circuit unit on the large current side, so that the power conversion on the large current side is compared to the power conversion circuit unit on the small current side. It is preferable that the circuit portion is easily selected. Therefore, the number of times of selection and setting of the optimum integrated value range corresponding to the power conversion circuit unit on the large current side is small, and the number of times of selection and setting of the optimum integrated value range corresponding to the power conversion circuit unit on the small current side may be set large.

A selection process for selecting one power conversion circuit unit will be described with reference to FIG. FIG. 13 is a flowchart illustrating another example of the selection process of the power conversion circuit unit. In order to simplify the description, a case where the power conversion circuit unit is selected from the first power conversion circuit unit 4 and the second power conversion circuit unit 5 will be described. The same applies when there are three or more power conversion circuit units. The number of times of selection and setting of the first optimum integrated value range corresponding to the first power conversion circuit unit 4 is 3 times, and the number of times of selection and setting of the second optimum integrated value range corresponding to the second power conversion circuit unit 5 is 2 times. . Since there are only two power conversion circuit units, it is not necessary to provide an upper limit for the second optimum integrated value range.

First, the selection unit 14 determines whether or not the input current integration value Iint detected by the input current integration detection unit 10 is included in the second optimum integration value range stored in the optimum integration value range storage unit 13. (# 31).

When the detected input current integrated value Iint is included in the second optimal integrated value range (Yes in # 31), the input current integrated value Iint is continuously included in the second optimal integrated value range by the selection unit 14. Is detected (# 32).

Whether the number of times the input current integrated value Iint is continuously included in the second optimum integrated value range is the selected set number, that is, whether the input current integrated value Iint is within the second optimal integrated value range Is determined by the selection unit 14 (# 33).

If the input current integrated value Iint is within the second optimum integrated value range twice consecutively (Yes in # 33), the second power conversion circuit unit 5 is selected by the selection unit 14 (# 34).

When the selection unit 14 determines in step # 31 that the input current integrated value Iint is not included in the second optimal integrated value range (No in # 31), the input current integrated value Iint is the first optimal integrated value. It should be included in the integrated value range. The selection unit 14 detects whether or not the input current integrated value Iint is continuously included in the first optimum integrated value range (# 35).

Whether the number of times the input current integrated value Iint is continuously included in the first optimal integrated value range is the selected set number, that is, whether the input current integrated value Iint is within the first optimal integrated value range Is determined by the selection unit 14 (# 36).

If the input current integrated value Iint is within the first optimum integrated value range for three consecutive times (Yes in # 36), the first power conversion circuit unit 4 is selected by the selection unit 14 (# 37).

In each of the steps # 34 and # 37, after the first and second power conversion circuit units 4 to 5 are selected, the control condition determination unit 15 obtains the largest output power in each selected power conversion circuit unit. Control conditions (duty ratio, target value of the output voltage Vout, switching frequency, etc.) are determined (# 38), and the selection process ends.

In step # 33, if the number of times the input current integrated value Iint is within the second optimum integrated value range is less than twice, that is, the input current integrated value Iint is within the first optimum integrated value range before continuing twice. If it is (No in # 33), the selection process is terminated.

In step # 36, if the number of times the input current integrated value Iint is within the first optimum integrated value range is less than 3, that is, before the input current integrated value Iint continues to be 3 times, the input current integrated value Iint is the second optimal integrated value. If it is within the range (No in # 36), the selection process is terminated.

The method for determining the target value of the output voltage Vout in the selected power conversion circuit unit may be the same as described above. When the selection process is completed, it is determined whether or not the power conversion circuit unit needs to be switched in # 11 of FIG.

Switching of the power conversion circuit unit in the power conversion apparatus 100 using the selection process according to the flowchart of FIG. 13 will be described with reference to FIG. FIG. 14 is a timing chart showing an example of switching of the power conversion circuit unit using the selection process of the flowchart of FIG.

In FIG. 14, the upper part shows the relationship between the input current integrated value Iint and time, and the lower part shows the power conversion circuit unit selected when the input current integrated value Iint changes with time as shown in the upper part. FIG. Note that FIG. 14 is the same as FIG. 11 except that the switching timing of the power conversion circuit unit shown in the lower stage is different, and thus detailed description thereof is omitted. The input current integrated value Iint in the upper part of FIG. 14 is the same as that in the upper part of FIG. Since there are only two power conversion circuit units, the upper limit value (I2) is not provided for the second optimum integrated value range, and the range may be larger than I1.

In the first cycle, the input current integrated value Iint exceeds I1 and is included in the second optimum integrated value range. However, since the input current integrated value Iint is included in the second optimum integrated value range for the first time this time, the process waits until the next input current integrated value Iint is detected.

Also in the second cycle, the input current integrated value Iint is included in the second optimum integrated value range. Thus, the number of times that the input current integrated value Iint is continuously included in the second optimum integrated value range is two. Since the second optimum integrated value range is selected and set twice, the power conversion control unit 1 selects the second power conversion circuit unit 5 and switches the power conversion circuit unit.

In the third period, since the input current integrated value Iint is equal to or less than I1, it is included in the first optimum integrated value range. However, since the input current integrated value Iint is included in the first optimum integrated value range for the first time this time, the process waits until the next input current integrated value Iint is detected.

Also in the fourth cycle, the input current integrated value Iint is included in the first optimal integrated value range. However, since the number of times of selection and setting of the first optimum integrated value range is three and the input current integrated value Iint is included in the first optimum integrated value range for the second time this time, the next input current integrated value Iint is Wait until it is detected.

In the fifth cycle, the input current integrated value Iint is included in the second optimum integrated value range. Since the number of times that the input current integrated value Iint is included in the first optimal integrated value range is less than three consecutive times, the current selection process ends. Since the input current integrated value Iint is included in the second optimum integrated value range and the input current integrated value Iint is included in the second optimal integrated value range for the first time this time, the next input current integrated value Iint Wait until is detected.

In the sixth period, the input current integrated value Iint is included in the first optimal integrated value range. Since the number of times that the input current integrated value Iint is included in the second optimum integrated value range is less than twice in succession, the current selection process ends. Since the input current integrated value Iint is included in the first optimum integrated value range and the input current integrated value Iint is included in the first optimal integrated value range for the first time this time, the next input current integrated value Iint Wait until is detected.

Also in the seventh cycle, the input current integrated value Iint is included in the first optimal integrated value range. Since the input current integrated value Iint is included in the first optimum integrated value range for the second time this time, the process waits until the next input current integrated value Iint is detected.

Also in the eighth cycle, the input current integrated value Iint is included in the first optimum integrated value range. As a result, the input current integrated value Iint is continuously included in the first optimum integrated value range three times, and the power conversion control unit 1 selects the first power conversion circuit unit 4, so that the power conversion circuit The part is switched.

Also in the ninth cycle, the input current integrated value Iint is included in the first optimum integrated value range. Since the first power conversion circuit unit 4 is selected and the selection process is completed in the eighth period, the input current integrated value Iint is included in the first optimum integrated value range for the first time this time. Therefore, it waits until the next integrated input current value Iint is detected.

In the tenth cycle, the input current integrated value Iint is included in the second optimum integrated value range. Since the number of times that the input current integrated value Iint is included in the first optimal integrated value range is less than three consecutive times, the current selection process ends. Since the input current integrated value Iint is included in the second optimum integrated value range and the input current integrated value Iint is included in the second optimal integrated value range for the first time this time, the next input current integrated value Iint Wait until is detected.

Also in the 11th cycle, the input current integrated value Iint is included in the second optimum integrated value range. As a result, the number of times the input current integrated value Iint is continuously included in the second optimum integrated value range is two times, and the second power conversion circuit unit 5 is selected by the power conversion control unit 1. The part is switched.

According to the present embodiment, the power conversion circuit unit is selected when the input current integrated value Iint is continuously included in the same optimum integrated value range for the selected set number of times. Since the selection process is not performed every time the input current integrated value Iint is detected, the number of switching of the power conversion circuit unit can be reduced. Since the power conversion circuit unit is selected based on the integrated input current value Iint, the number of times of switching can be suppressed while maintaining high conversion efficiency η.

In addition, since it is easier to select the power conversion circuit unit on the large current side than the power conversion circuit unit on the small current side, there is a case where a power conversion circuit unit that does not correspond to the input current Iin is selected. However, the conversion efficiency η does not decrease significantly.

The above-described power conversion device 100 that selects the power conversion circuit unit when the input current integrated value Iint is continuously included in the same optimum integrated value range for the number of times selected and set, even if the input current Iin suddenly increases. If the integrated input current value Iint is not detected the selected number of times, the power conversion circuit unit is not switched.

For example, even when the output of the solar cell PV suddenly increases, such as when the sun with clouds is suddenly coming out, the power conversion circuit unit is switched from the small current side to the large current side power conversion circuit unit. The change is made after the integration time necessary for detection of the input current integration value Iint × the number of selected selections. In such a case, the loss increases because the input of the large current must be converted by the power conversion circuit unit on the small current side for the above time.

Therefore, the optimum integrated value range of the power conversion circuit on the large current side is divided into two, and the large current side range (large current side optimum range) and the small current side range (small current side optimum range) are set. When the power conversion circuit section on the small current side is selected and operating, the input current integrated value Iint is within the large current side optimum range within the optimum integrated value range of the power conversion circuit section on the large current side. Is included, it is preferable that the power conversion circuit unit corresponding to the optimum integrated value range is selected without waiting for the selected set number of times. The lower limit of the large current side optimum range may be set in consideration of the fact that the power conversion circuit is switched when the input current integrated value Iint is included in the large current side optimum range. The optimum range may be a range lower than the optimum range on the large current side.

When the power conversion circuit section on the small current side is selected and controlled, the input current integrated value Iint is included in the large current side optimum range within the optimum integrated value range of the power conversion circuit section on the large current side. In such a case, the selection unit 14 may select a power conversion circuit unit corresponding to the optimum integrated value range.

In addition to the optimum integrated value range corresponding to each power conversion circuit unit, the optimum integrated value range storage unit 13 also includes a large current side optimum range and a small current side optimum range set in each optimum integrated value range. It may be stored. Note that the setting of the optimum range for the large current side and the optimum range for the small current side is performed in order to switch to the power conversion circuit section on the large current side more quickly in response to the sudden increase in the input current Iin. In the power conversion circuit unit (first power conversion circuit unit 4) having a small input current range, the large current side optimum range and the small current side optimum range may not be set.

A selection process for selecting one power conversion circuit unit in the power conversion apparatus 100 will be described with reference to FIG. FIG. 15 is a flowchart showing still another example of the selection process of the power conversion circuit unit. Similar to the description of the selection process in FIG. 13, a case where the power conversion circuit unit is selected from the first power conversion circuit unit 4 and the second power conversion circuit unit 5 will be described. Similarly to the selection processing of FIG. 13, the number of times of selection and setting of the first optimum integrated value range corresponding to the first power conversion circuit unit 4 is three, and the second optimal integration corresponding to the second power conversion circuit unit 5 is performed. The value range selection setting count is two.

First, whether or not the input current integrated value Iint detected by the input current integration detection unit 10 is included in the large current side optimal range within the second optimal integrated value range stored in the optimal integrated value range storage unit 13. Is selected by the selection unit 14 (# 41).

When the detected input current integrated value Iint is included in the high current side optimum range (Yes in # 41), the second power conversion circuit unit 5 is selected by the selection unit 14 (# 45). When the detected input current integrated value Iint is not included in the large current side optimal range (No in # 41), the detected input current integrated value Iint is stored in the optimal integrated value range storage unit 13. It is judged by the selection part 14 whether it is included in the small electric current side optimal range within the 2nd optimal integrated value range (# 42).

If the detected input current integrated value Iint is included in the small current side optimum range (Yes in # 42), is the selection unit 14 continuously including the input current integrated value Iint within the small current side optimum range? It is detected (# 43).

Select whether the number of times the input current integrated value Iint is continuously included in the small current side optimum range is the selected set number, that is, whether the input current integrated value Iint is continuously within the small current side optimum range This is determined by the unit 14 (# 44).

When the input current integrated value Iint is within the small current side optimum range for two consecutive times (Yes in # 44), the second power conversion circuit unit 5 is selected by the selection unit 14 (# 45).

When the selection unit 14 determines in step # 42 that the input current integrated value Iint is not included in the small current side optimal range (No in # 42), the input current integrated value Iint is the first optimal integrated value. Should be included in the value range. The selection unit 14 detects whether the input current integrated value Iint is continuously included in the first optimal integrated value range (# 46).

Whether the number of times the input current integrated value Iint is continuously included in the first optimal integrated value range is the selected set number, that is, whether the input current integrated value Iint is within the first optimal integrated value range Is determined by the selection unit 14 (# 47).

If the input current integrated value Iint is within the first optimum integrated value range for three consecutive times (Yes in # 47), the first power conversion circuit unit 4 is selected by the selection unit 14 (# 48).

In each of the steps # 45 and # 48, after the first to second power conversion circuit units 4 to 5 are selected, the control condition determination unit 15 obtains the largest output power in each selected power conversion circuit unit. Control conditions (duty ratio, target value of output voltage Vout, switching frequency, etc.) are determined (# 49), and the selection process ends.

In the process of # 44, when the number of times the input current integrated value Iint is within the small current side optimum range is less than twice (No in # 33), the selection process is terminated.

In the process of # 48, when the number of times the input current integrated value Iint is within the first optimum integrated value range is less than 3 (No in # 36), the selection process is terminated.

The switching of the power conversion circuit unit in the power conversion apparatus 100 using the selection process according to the flowchart of FIG. 15 will be described with reference to FIG. FIG. 16 is a timing chart showing an example of switching of the power conversion circuit unit using the selection process of the flowchart of FIG.

16, the horizontal axis of the vertical axis in the upper and lower diagrams is the same as the upper and lower diagrams in FIG. 11, but the change in the input current integrated value Iint and the lower switching timing are different from those in FIG. In addition, in the upper diagram of FIG. 16, I21 that is a boundary between the large current side optimum range and the small current side optimum range within the second optimum integrated value range is added.

In the second optimum integrated value range, a range larger than I1 and not more than I21 is set as a small current side optimum range, and a range larger than I21 and not more than I2 is set as a large current side optimum range. Since there are only two power conversion circuit units, the upper limit value (I2) may not be provided for the second optimum integrated value range, and the large current side optimum range may be a range larger than I21.

In the first cycle, the integrated input current value Iint is greater than I1 and less than or equal to I21, so it is included in the small current side optimum range. However, since the input current integrated value Iint is included in the small current side optimum range for the first time this time, it waits until the next input current integrated value Iint is detected.

Also in the second cycle, the input current integrated value Iint is included in the small current side optimum range. As a result, the number of times that the integrated input current value Iint is continuously included in the small current side optimum range is two. Since the second optimum integrated value range (small current side optimum range) is selected and set twice, the power conversion control unit 1 selects the second power conversion circuit unit 5 and switches the power conversion circuit unit.

Also in the fifth cycle, the input current integrated value Iint is included in the first optimum integrated value range. As a result, the input current integrated value Iint is continuously included in the first optimum integrated value range three times, and the power conversion control unit 1 selects the first power conversion circuit unit 4, so that the power conversion circuit The part is switched.

In the sixth cycle, the input current integrated value Iint is larger than I21, so the input current integrated value Iint is included in the large current side optimal range within the second optimal integrated value range. Therefore, the second power conversion circuit unit 5 is selected by the power conversion control unit 1, and the power conversion circuit unit is switched.

In the 7th cycle, the input current integrated value Iint is included in the small current side optimum range. Since the input current integrated value Iint is included in the first optimum integrated value range for the first time this time, the process waits until the next input current integrated value Iint is detected.

Also in the eighth cycle, the input current integrated value Iint is included in the small current side optimum range. As a result, the number of times the input current integrated value Iint is continuously included in the second optimum integrated value range is two times, and the second power conversion circuit unit 4 is selected by the power conversion control unit 1, but the second Since the power conversion circuit unit 5 is selected, the selection process ends without switching the power conversion circuit unit.

In the ninth cycle, the input current integrated value Iint is included in the first optimum integrated value range. However, since the input current integrated value Iint is included in the first optimum integrated value range for the first time this time, the process waits until the next input current integrated value Iint is detected.

In the tenth cycle, the input current integrated value Iint is included in the first optimum integrated value range. However, since the number of times of selection and setting of the first optimum integrated value range is three and the input current integrated value Iint is included in the first optimum integrated value range for the second time this time, the next input current integrated value Iint is Wait until it is detected.

Also in the 11th cycle, the input current integrated value Iint is included in the first optimum integrated value range. As a result, the input current integrated value Iint is continuously included in the first optimum integrated value range three times, and the power conversion control unit 1 selects the first power conversion circuit unit 4, so that the power conversion circuit The part is switched.

According to the present embodiment, in addition to the power conversion circuit unit being selected when the input current integrated value Iint is continuously included in the same optimal integrated value range for the selected set number of times, the input current integrated value Iint is large within the optimal integrated value range. When the current-side optimum range is set and the power conversion circuit section on the small current side is selected and operating, it is within the optimum range of the large current side within the optimum integrated value range of the power conversion circuit section on the larger current side When the input current integrated value Iint is included, the power conversion circuit unit corresponding to the optimum integrated value range is selected without waiting for the selected set number of times. Thereby, even when the input current Iin changes suddenly, the power conversion circuit unit can be quickly switched in response to the change in the input current Iin, and high conversion efficiency η can be maintained.

(Other embodiments)
The power conversion device 100 according to the present embodiment selects any one power conversion circuit unit based on the input current integrated value Iint, but not only based on the input current integrated value Iint but also input within a predetermined time. Any one of the power conversion circuit units may be selected based on the maximum value of the current Iin (maximum input current Imax). The power conversion device 100B according to another embodiment selects any one power conversion circuit unit based on both the input current integrated value Iint and the maximum input current Imax. The maximum input current Imax may be the maximum value of the input current Iin within the integration time.

A configuration of a power conversion device 100B according to another embodiment will be described with reference to FIG. FIG. 17 is a block diagram illustrating an example of a configuration of a power conversion device according to another embodiment. In the power conversion device 100B, members having the same functions as those of the components of the power conversion device 100 described above are denoted by the same reference numerals, and description thereof is omitted. The power conversion device 100B has a maximum input current calculation unit 16 and an input current threshold storage unit 17, and is different from the power conversion device 100 in that a selection unit 14B is provided instead of the selection unit 14.

In addition to the function of the selection unit 14 described above, the selection unit 14B selects any one of the power conversion circuit units based on the maximum input current Imax, and selects based on the power conversion circuit unit and the integrated input current value Iint. The power conversion circuit unit is compared with the selected power conversion circuit unit, and one of the power conversion circuit units is selected.

Specifically, the selection unit 14B selects the first candidate for the power conversion circuit unit based on the integrated input current value Iint as described with reference to FIG. Furthermore, the selection unit 14B selects the second candidate for the power conversion circuit unit by comparing the maximum input current Imax with the threshold value stored in the input current threshold value storage unit 17. When the two power conversion circuit units that are the first candidate and the second candidate are the same, the selection unit 14B finally selects the power conversion circuit unit. When the two power conversion circuit units that are the first candidate and the second candidate are different from each other, a power conversion circuit unit on the larger current side, that is, a power conversion circuit unit having a larger input current range is selected from among them. Finally select.

When the selected power conversion circuit unit is different, the large-current-side power conversion circuit unit is selected as described above because it is larger than the small-current-side power conversion circuit unit is used with a large current. This is because the loss is lower when the current-side power conversion circuit unit is used with a small current.

The maximum input current calculation unit 16 includes a storage element such as a RAM that can temporarily store data. The maximum input current calculation unit 16 calculates the maximum value of the input current Iin within the integration time. Specifically, simultaneously with the start of integration of the input current integrated value Iint, the detected value of the input current Iin is input and stored in the maximum input current calculation unit 16, but the newly input value of the input current Iin is stored. If the detected value is larger than the currently stored detection value, the newly input detection value is stored, and the currently stored detection value is erased. The operation is performed until the detection of the integrated input current value Iint is completed, and the detected value of the input current Iin that is finally stored is sent to the selection unit 14B as the maximum input current Imax.

The input current threshold storage unit 17 is composed of a nonvolatile memory or the like. When the power conversion is performed using the first to third power conversion circuit units 4 to 6, the input current threshold storage unit 17 preferably switches the power conversion circuit unit in order to obtain the largest output power Pout. Threshold values th1 and th2 which are values of the input current Iin are stored. Since the threshold values th1 and th2 have already been described with reference to FIG. 4, the description thereof is omitted here. The small current side threshold th1 and the large current side threshold th2 may be obtained by measurement in advance and stored in the input current threshold storage unit 17.

The switching process of the power conversion circuit unit in the power conversion device 100B according to another embodiment is the same as the flowchart shown in FIG.

With reference to FIG. 18, the selection process of the power inverter circuit unit in the power converter 100B according to another embodiment will be described. First, steps # 21 to # 26 shown in FIG. 10 are performed by the selection unit 14B, and any one of the first to third power conversion circuit units 4 to 6 is selected. (# 51).

In parallel with the step # 51, the selection unit 14B selects any one power conversion circuit unit based on the maximum input current Imax (# 52). This process will be described in detail later.

The selection unit 14B compares the power conversion circuit unit selected in the step # 51 with the power conversion circuit unit selected in the step # 52 (# 53).

When both of the compared power conversion circuit units are the same (Yes in # 53), the power conversion circuit unit is finally selected by the selection unit 14B (# 54).

When the compared power conversion circuit units are different (No in # 53), the selection unit 14B finally selects the power conversion circuit unit on the large current side from them (# 55), and the selection process Ends.

Control conditions (duty ratio, target value of output voltage Vout, switching frequency, etc.) that can obtain the largest output power in the finally selected power conversion circuit unit are determined by the control condition determination unit 15 (# 56). .

Referring to FIG. 19, the combination of the power conversion circuit unit selected in step # 51 and the power conversion circuit unit selected in step # 52, and the power conversion finally selected in these combinations The circuit unit will be described. FIG. 19 is a table showing the relationship between the combination of the selection result based on the integrated input current value and the selection result based on the maximum input current, and the selected power conversion circuit unit.

As shown in FIG. 19, when the first power conversion circuit unit 4 is selected based on the integrated input current value Iint, the power conversion circuit unit selected based on the maximum input current Imax is finally selected. .

When the second power conversion circuit unit 5 is selected based on the integrated input current value Iint, the second power conversion circuit is used except when the third power conversion circuit unit 6 is selected based on the maximum input current Imax. When the unit 5 is finally selected and the third power conversion circuit unit 6 is selected based on the maximum input current Imax, the third power conversion circuit unit 6 is finally selected.

When the third power conversion circuit unit 5 is selected based on the integrated input current value Iint, the third power conversion circuit unit 6 is not related to the power conversion circuit unit selected based on the maximum input current Imax. Finally selected.

Next, with reference to FIG. 20, a method for selecting the power conversion circuit unit based on the maximum input current Imax, which is the step # 52 of FIG. 18, will be described. First, calculation of the maximum input current Imax will be described. Specifically, the maximum input current Imax is calculated by the steps # 61 to # 64 in FIG.

The input current Iin is detected by the input current detector 2 simultaneously with the timing of starting the integration of the input current Iin for detecting the input current integrated value Iint (# 61).

The maximum input current calculation unit 16 compares the detected value of the input current Iin with the maximum input current Imax stored in the maximum input current calculation unit 16 (# 62). At the start of measurement of the maximum input current Imax, the maximum input current Imax stored in the maximum input current calculation unit 16 is set to 0A.

If the detected value of the input current Iin is not larger than the currently stored maximum input current Imax (No in # 62), the process proceeds to step # 64.

If the detected value of the input current Iin is larger than the currently stored maximum input current Imax (Yes in # 62), the maximum input current Imax is updated to the detected value of the input current Iin (# 63).

The maximum input current calculation unit 16 determines whether or not the integration time that is a predetermined time for detecting the input current integration value Iint has elapsed (# 64), and if it has not elapsed (No in # 64), again. Return to step # 61.

When the integration time has elapsed (Yes in # 64), the maximum input current Imax stored in the maximum input current calculation unit 16 at that time is the calculated maximum input current Imax, and is sent to the selection unit 14B. Then, the selection processing after the step # 65 is performed. The maximum input current calculation unit 16 resets the stored maximum input current Imax to 0 A, and starts calculating the maximum input current Imax within the next integration time.

The selection unit 14B compares the calculated maximum input current Imax with the large current side threshold th2 stored in the input current threshold storage unit 17 (# 65).

If the maximum input current Imax is greater than or equal to the large current side threshold th2 (Yes in # 65), the third power conversion circuit unit 6 is selected by the selection unit 14B (# 66).

When the maximum input current Imax is smaller than the large current side threshold th2 (No in # 65), the selection unit 14B causes the maximum input current Imax and the small current side stored in the input current threshold storage unit 17 to be reduced. The threshold value th1 is compared (# 67). If the maximum input current Imax is equal to or greater than the small current side threshold th1 (Yes in # 67), the second power conversion circuit unit 5 is selected by the selection unit 14B (# 68).

When the maximum input current Imax is smaller than the small current side threshold th1 (No in # 67), the first power conversion circuit unit 4 is selected by the selection unit 14B (# 69).

Since the power conversion device 100B according to another embodiment selects the power conversion circuit unit based not only on the input current integrated value Iint but also on the maximum input current Imax as described above, a preferable power conversion circuit Parts are selected with higher accuracy. Further, since the selection process is performed every integration time, the number of times of switching of the power conversion circuit unit is suppressed, and an increase in loss due to switching can be suppressed.

In the above description, the method according to the flowchart shown in FIG. 10 is used to select the power conversion circuit unit based on the integrated input current value Iint. However, the method according to the flowchart shown in FIG. Good.

The

power conversion devices

100 and 100B according to the present embodiment have a plurality of power conversion circuit units having different input current-output power characteristics, and maintain high conversion efficiency in a wide input current range by switching them. Can do. Therefore, the configuration is not complicated and can be simplified, and the circuit design is easy. In addition, compared to power converters that have multiple identical circuits and combine them to accommodate a wide input current range, the increase in the number of parts for configuring the circuit is suppressed and a wide input current range is achieved. On the other hand, an output can be obtained efficiently. Therefore, downsizing and cost reduction are possible.

In addition, since the power conversion circuit unit is switched based on the integrated input current value, the number of switching of the power conversion circuit unit can be suppressed, and unnecessary switching can be eliminated. It can be carried out.

In the embodiment described above, the structure, shape, dimensions, number, material, composition, etc. of the entire

power conversion device

100, 100B or each part can be appropriately changed in accordance with the spirit of the present invention.

The

power converters

100 and 100B according to the above-described embodiments have a wide input current range and an output current range, and can output maximum power in the entire current range in response to fluctuations in a wide range of input current. And loss is small. Further, downsizing and cost reduction are possible. For example, the power generated by the solar cell can be taken out more effectively by connecting to the solar cell. Therefore, it can be suitably used as a component of a solar power generation system.

DESCRIPTION OF SYMBOLS 1 Power conversion control part 2 Input current detection part 3 Input voltage detection part 4 1st power conversion circuit part 5 2nd power conversion circuit part 6 3rd power conversion circuit part 7 Output current detection part 8 Output voltage detection part 9 Alarm output part DESCRIPTION OF SYMBOLS 10 Input current integration detection part 12 Efficiency vs. output current data storage part 13 Optimal integrated value

range storage part

14, 14B Selection part 15 Control condition determination part 16 Maximum input current calculation part 17 Input current threshold

value storage part

100, 100B Power conversion Device 200 Matching device for interconnection L1-3 Coil C1-3 Capacitor FET1-3 Switching element D1-3 Commutation diode DT1-3 Efficiency vs. output current data PV Solar cell

Claims

A power conversion device that converts input power input as DC power and outputs the power,
An input current integration detection unit that repeatedly detects an input current integration value that is an integration value over a predetermined time of the input current that is the current of the input power;
A plurality of power conversion circuit units that convert the input power into power, and have different input current ranges and overlapping with adjacent input current ranges;
Control that selects one power conversion circuit unit from the plurality of power conversion circuit units based on the detected integrated input current value, and obtains the largest output power for the selected one power conversion circuit unit A power conversion control unit that performs control under conditions;
A power conversion device.
The power conversion control unit includes a plurality of optimum integrated values in which the input current integrated value detected by the input current integration detecting unit is an optimum range of the input current integrated value corresponding to each of the plurality of power conversion circuit units. A selection unit that determines which of the ranges is included in the optimum integrated value range and selects the power conversion circuit unit corresponding to the corresponding optimum integrated value range as the one power conversion circuit unit;
The power conversion device according to claim 1.
It further includes an input current detection unit for detecting the input current,
The power conversion control unit is configured to repeatedly calculate a maximum input current within the predetermined time from an input current detected by the input current detection unit, and
In selecting the one power conversion circuit unit, the first candidate of the power conversion circuit unit is selected based on the integrated input current value, and the second candidate of the power conversion circuit unit is selected based on the maximum input current. A selection unit that selects the power conversion circuit unit having a larger input current range as the one power conversion circuit unit from among the power conversion circuit units that are the first candidate and the second candidate.
The power conversion device according to claim 1.
The power conversion control unit selects a power conversion circuit unit that obtains the largest output power at the calculated maximum input current when selecting the power conversion circuit unit based on the maximum input current.
The power conversion device according to claim 3.
The power conversion control unit includes a plurality of optimum integrated values in which the input current integrated value detected by the input current integration detecting unit is an optimum range of the input current integrated value corresponding to each of the plurality of power conversion circuit units. It is repeatedly determined which of the ranges is within the optimum integrated value range, and when the input current integrated value is continuously included in the same optimum integrated value range for a predetermined number of times, the optimum A selection unit that selects the power conversion circuit unit corresponding to an integrated value range as the one power conversion circuit unit;
The power conversion device according to claim 1.
The predetermined number of times varies depending on the selected power conversion circuit unit,
When the power conversion circuit unit having a small input current range is selected as the one power conversion circuit unit, the power conversion circuit unit having a larger input current range is selected as the one power conversion circuit unit. More than the predetermined number of times when
The power conversion device according to claim 5.
The optimal integrated value range includes a large current side optimal range in which the input current integrated value is large, and a small current side optimal range in which the input current integrated value is small,
The selection unit includes the optimum integration corresponding to the power conversion circuit unit in which the input current integration value detected by the input current integration detection unit is larger in the input current range than the currently selected power conversion circuit unit. When included in the large current side optimum range of the value range, the power conversion circuit unit corresponding to the optimum integrated value range is selected as the one power conversion circuit unit,
The selection unit includes the optimum integration value corresponding to the power conversion circuit unit in which the input current integration value detected by the input current integration detection unit is larger in the input current range than the currently selected power conversion circuit unit. In the case where the small current side optimum range of the range is continuously included twice or more times, the power conversion circuit unit corresponding to the optimum integrated value range is selected as the one power conversion circuit unit. ,
The power conversion device according to claim 5.
Each of the plurality of power conversion circuit units includes a switching element, a coil for storing energy during power conversion, and a capacitor.
The inductances of the coils provided in each of the plurality of power conversion circuit units are different from each other.
The power converter device in any one of Claim 1 to 7.
A solar cell that converts incident light and outputs power;
The power conversion device according to any one of claims 1 to 8, wherein the output of the solar cell is converted into power.
An interconnection matching device that converts the output of the power converter into a frequency and voltage of commercial power;
A solar power generation system comprising: