JP2016063575A - Power conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conditioner capable of avoiding a stop of autonomous operation and maintaining electric power supply to a load by properly controlling output voltages to a single-phase three-wire type electric power line.SOLUTION: A power conditioner connected to a single-phase three-wire type electric power line and a DC power source comprises an inverter which converts DC electric power of the DC power source into AC electric power of a single-phase three-wire type and a control unit which controls the inverter. The control unit receives a first voltage value of a first phase and a second voltage value of a second phase, receives a first current value of a first voltage line, and controls a voltage output from the inverter for the first phase and second phase upon the basis of the first and second voltage values and the first current value. The control unit instructs the inverter to lower a voltage output for the first phase below the first voltage value and also to make a voltage output for the second phase equal to or lower than the second voltage value when the first current value is equal to or higher than a reference current value.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a power conditioner, and more particularly, to a power conditioner capable of converting DC power into single-phase, three-wire AC power.

  2. Description of the Related Art In recent years, a distributed power supply system including a solar battery and a storage battery such as a lithium ion battery that have little influence on the environment has been widely used in general households. In such a distributed power supply system, a power conditioner that converts DC power generated by a solar cell or the like into AC power is used. Some power conditioners operate in conjunction with a commercial AC power system.

  In a commercial AC power system, for example, a single-phase three-wire system is used. In the single-phase three-wire system, 100 V is provided between the voltage line U and the neutral line O (also referred to as “U phase”) and between the voltage line V and the neutral line O (also referred to as “V phase”). AC power is supplied. The power conditioner configured to be capable of being connected to a single-phase three-wire AC power system is configured to be able to output AC power to the U phase and the V phase.

  In addition, when the AC power system becomes unavailable (for example, during a power failure), the power conditioner starts a self-sustained operation that operates independently from the AC power system, and converts DC power from solar cells to AC. It converts into electric power and outputs it to U phase and V phase.

  As a technique related to power conversion, for example, Japanese Patent Laid-Open No. 2000-102265 (Patent Document 1) discloses a power conversion device for photovoltaic power generation. In this power converter, a plurality of capacitors are connected in series between DC input sections, a switch is provided between the connection section of these capacitors and the output line of the inverter circuit, and this switch is opened and closed according to the system power supply. Thus, the control of the inverter circuit can be switched.

JP 2000-102265 A

  However, during the independent operation of the power conditioner, the current of the voltage line U or the voltage line V becomes larger than the reference value due to an inrush current or the like, or the voltage of one phase (for example, U phase) becomes larger than the reference value. Anomalies may be detected. In the technique disclosed in Japanese Patent Application Laid-Open No. 2000-102265, the control of the inverter circuit is switched by opening and closing the switch, but the countermeasure for the case where the above abnormality is detected during the output of power from the inverter No measures are taken into account.

  The present invention has been made in order to solve the above-described problems, and an object in one aspect is to stop autonomous operation by appropriately controlling the output voltage to the single-phase three-wire power line. It is an object of the present invention to provide a power conditioner capable of avoiding the problem and maintaining the power supply to the load.

  According to an embodiment, a power conditioner is provided that is connected to a single-phase three-wire power line having first and second voltage lines and a neutral line, and a DC power source. An inverter that converts DC power of a DC power source into single-phase three-wire AC power and a control unit that controls the inverter are provided. The control unit includes a first voltage value of the first phase composed of the first voltage line and the neutral line, and a second voltage value of the second phase composed of the second voltage line and the neutral line. From the inverter based on the voltage input means for receiving the current input means, the current input means for receiving the first current value of the first voltage line, the first and second voltage values, and the first current value. And a voltage control unit for controlling the voltage output to the phase and the second phase. The voltage control unit lowers the voltage output to the first phase below the first voltage value when the first current value is equal to or higher than the reference current value, and sets the voltage output to the second phase to The inverter is instructed to make the voltage value 2 or less.

  According to the present disclosure, by appropriately controlling the output voltage to the single-phase three-wire power line, it is possible to avoid the stop of the self-sustaining operation and maintain the power supply to the load.

It is the schematic of the whole structure of the electric power supply system to which the power conditioner according to Embodiment 1 is applied. It is a figure which shows the structure of the power conditioner according to Embodiment 1. It is a figure for demonstrating the outline | summary of the control system of the power conditioner according to related technology. It is a figure for demonstrating the outline | summary of the control system of the power conditioner according to Embodiment 1. FIG. FIG. 3 is a schematic diagram showing a configuration of a control unit according to the first embodiment. It is a graph which shows an example of an overvoltage value. It is a figure for demonstrating a voltage control system (the 1). It is a figure for demonstrating a voltage control system (the 2). It is a figure for demonstrating a voltage control system (the 3). 6 is a flowchart for illustrating a processing procedure of a control unit according to the first embodiment. It is a figure which shows the structure of the power conditioner according to Embodiment 2. FIG. FIG. 7 is a schematic diagram showing a configuration of a control unit according to a second embodiment. It is a figure for demonstrating the production | generation system of a switching control signal. 10 is a flowchart for illustrating a processing procedure of a control unit according to the second embodiment. It is a figure which shows the structure of the power conditioner according to Embodiment 3. FIG. It is a figure which shows the structure of the power conditioner according to Embodiment 4. It is a schematic diagram which shows the structure of the control part according to Embodiment 4.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
<Overall configuration>
FIG. 1 is a schematic diagram of an overall configuration of a power supply system to which a power conditioner according to the first embodiment is applied.

  Referring to FIG. 1, the power supply system includes a power conditioner 2, a power line 3, a DC power supply 4, an AC power system 6, and load groups 300A, 300B, and 300C (hereinafter also referred to as “load group 300”). .). A part of the power supply system is installed in a house such as a house or an office, for example.

  The power line 3 includes a voltage line U, a neutral line O, and a voltage line V. The power line 3 is wired in the house through a distribution board (not shown), and is connected between any two of the grounded neutral line O and the voltage lines U and V on both sides. Supply power to the load.

  Specifically, the power line 3 is a single-phase three-wire power line. An AC voltage (for example, 100 V) is output (supplied) between the voltage line U and the neutral line O (first phase) and between the voltage line V and the neutral line O (second phase). . The AC voltage output between the voltage line U and the voltage line V is larger than the AC voltage output to the first phase and the AC voltage output to the second phase, for example, 200V.

  In the present disclosure, the voltage line U and the neutral line O, that is, the first phase is hereinafter also referred to as “U phase”. The voltage line V and the neutral line O, that is, the second phase is hereinafter also referred to as “V phase”.

  The voltage line U, the neutral line O, and the voltage line V are used with electric devices or the like connected as loads. In the example shown in FIG. 1, a load group 300 </ b> A is connected to a U phase (first phase) composed of a voltage line U and a neutral line O. A load group 300 </ b> B is connected to the V phase (second phase) configured by the voltage line V and the neutral line O. A load group 300 </ b> C is connected to the voltage line U and the voltage line V.

  The DC power source 4 generates DC power. The DC power source 4 is not particularly limited as long as it generates DC power, such as a solar cell, a fuel cell, a wind power generator, an electric vehicle, a plasma power generator, and a capacitor. The DC power supply may be a combination of these.

  The load group 300 includes a plurality of electric devices. The electric device is, for example, an AC 100 V fan, a vacuum cleaner, a refrigerator, or an AC 200 V air conditioner. Note that the electrical device is not limited to this, and may be a television, a personal computer, a microwave oven, or the like. In the present embodiment, load group 300 is composed of a plurality of electrical devices, but may be composed of a single electrical device.

  The power conditioner 2 converts DC power from the DC power supply 4 into U-phase AC power and V-phase AC power, and supplies (outputs) the load power to the load group 300. The load group 300 is also supplied with single-phase three-wire AC power from the AC power system 6.

  The power conditioner 2 can be connected to the AC power system 6 to supply AC power to the load group 300 (interconnection operation). The frequency of the AC power during the interconnection operation is a commercial frequency (for example, 50 Hz or 60 Hz). In the grid operation, power may be reversely flowed from the power conditioner 2 to the AC power system 6.

  Instead of the interconnected operation, the power conditioner 2 can also supply AC power to the load group 300 independently from the AC power system 6 (independent operation). The frequency of the AC power during the independent operation is controlled to be a frequency close to the commercial frequency, for example. During the independent operation, the AC power system 6 and the load group 300 may be electrically disconnected by a relay or breaker (not shown).

  The power conditioner 2 includes terminals 201 to 205. DC power from the DC power supply 4 is input to the terminals 204 and 205 via the DC bus 150. The DC bus 150 is a power line that transmits DC power supplied from the DC power supply 4 to the power conditioner 2. DC bus 150 includes a positive bus PL and a negative bus SL, which are power line pairs.

  The DC power input to the terminals 204 and 205 is converted into single-phase three-wire AC power and output to the terminals 201 to 203. A voltage line U is connected to the terminal 201. A neutral wire O is connected to the terminal 202. A voltage line V is connected to the terminal 203. For example, AC power with a voltage of 100 V is output between the terminal 201 and the terminal 202. AC power having a voltage of 100 V is output between the terminal 203 and the terminal 202. AC power having a voltage of 200 V is output between the terminal 201 and the terminal 203. The detailed configuration of the inverter 2 will be further described later with reference to FIG.

  The AC power system 6 is a single-phase three-wire commercial AC power system, and supplies power to the home via the power line 3. AC power system 6 is connected to voltage line U, neutral line O and voltage line V, that is, the U phase and the V phase. The AC power system 6 supplies AC power to the load group 300.

<Configuration of the inverter>
FIG. 2 is a diagram showing a configuration of the power conditioner 2 according to the first embodiment. Referring to FIG. 2, power conditioner 2 includes a control unit 10, an inverter 20, current sensors 41 and 42, voltage sensors 51 and 52, reactors L <b> 1 to L <b> 3, and terminals 201 to 205.

  The inverter 20 converts the DC power supplied from the DC power supply 4 via the DC bus 150 into AC power in accordance with the switching control signals S1 to S6 from the control unit 10, and the AC power obtained by the conversion is converted. Output to the power line 3.

  Inverter 20 includes a leg 21, a leg 22, and a leg 23 connected in parallel to each other. Leg 21 includes an upper arm (transistor Q1 and diode D1) and a lower arm (transistor Q2 and diode D2). Leg 22 includes an upper arm (transistor Q3 and diode D3) and a lower arm (transistor Q4 and diode D4). Leg 23 includes an upper arm (transistor Q5 and diode D5) and a lower arm (transistor Q6 and diode D6).

  Transistors Q1 and Q2 are connected in series between positive bus PL and negative bus SL forming DC bus 150. An intermediate point between transistor Q1 and transistor Q2 is connected to terminal 201 via reactor L1.

  Transistors Q3 and Q4 are connected in series between positive bus PL and negative bus SL. An intermediate point between transistor Q3 and transistor Q4 is connected to terminal 202 via reactor L2.

  Transistors Q5 and Q6 are connected in series between positive bus PL and negative bus SL. An intermediate point between transistors Q5 and Q6 is connected to terminal 203 via reactor L3.

  For example, IGBTs (Insulated Gate Bipolar Transistors) can be used as the transistors Q1 to Q6. Alternatively, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) may be used.

  Transistors Q1-Q6 are turned on / off in response to switching control signals S1-S6 from control unit 10, respectively. By turning on / off the transistors Q1 to Q6 at a predetermined timing, the DC power supplied from the DC power supply 4 can be converted into single-phase three-wire AC power.

  Current sensor 41 is provided between terminal 201 and reactor L1, for example. The current sensor 41 detects a current flowing through the voltage line U (hereinafter also referred to as “U-line current”), and inputs the detection result to the control unit 10. The detection result of the current sensor 41 includes information indicating the current value Iu of the U-line current. Current sensor 42 is provided between terminal 203 and reactor L3, for example. The current sensor 42 detects a current flowing through the voltage line V (hereinafter also referred to as “V-line current”), and inputs the detection result to the control unit 10. The detection result of the current sensor 42 includes information indicating the current value Iv of the V-line current.

  Voltage sensor 51 is connected between voltage line U and neutral line O, detects a U-phase voltage (hereinafter also simply referred to as “U-phase voltage”), and inputs the detection result to control unit 10. To do. The detection result of the voltage sensor 51 includes information indicating the voltage value Vu of the U-phase voltage. Voltage sensor 52 is connected between voltage line V and neutral line O, detects a V-phase voltage (hereinafter also simply referred to as “V-phase voltage”), and inputs the detection result to control unit 10. To do. The detection result of the voltage sensor 52 includes information indicating the voltage value Vv of the V-phase voltage.

  The control unit 10 controls the power supplied from the power conditioner 2 to the load group 300. The control unit 10 may be realized by hardware such as a circuit, or includes a CPU (Central Processing Unit) (not shown), and is realized by the CPU executing data and programs stored in a memory (not shown). It may be.

  Based on current values Iu and Iv received from current sensors 41 and 42 and voltage values Vu and Vv received from voltage sensors 51 and 52, control unit 10 performs transistors Q1 to Q6 according to a control method to be described later. Switching control signals S <b> 1 to S <b> 6 for controlling ON / OFF of the signal are generated and the switching control signals are output to the inverter 20.

<Outline of control method>
Here, with reference to FIG. 3 and FIG. 4, an outline of the control method of power conditioner 2 according to the first embodiment will be described in comparison with the control method of the related art of the present invention.

  FIG. 3 is a diagram for explaining an outline of a control method of the power conditioner according to the related art. FIG. 4 is a diagram for describing an overview of a control method of power conditioner 2 according to the first embodiment. In the following description, it is assumed that the power conditioner is operating independently.

  First, a related art control method will be described. Referring to FIG. 3, capacitor 5A is connected between voltage line U and neutral line O, capacitor 5B is connected between neutral line O and voltage line V, and capacitor 5C is connected to voltage line U. It is connected between the voltage lines V.

  Typically, the capacitor 5A is included in the load group 300A, the capacitor 5B is included in the load group 300B, and the capacitor 5C is included in the load group 300C. The capacitance of the capacitor 5A is a combined capacitance of a plurality of capacitors connected between the voltage line U and the neutral line O, and the capacitance of the capacitor 5B is between the voltage line V and the neutral line O. The combined capacitance of a plurality of capacitors connected, and the capacitance of the capacitor 5C is the combined capacitance of a plurality of capacitors connected between the voltage line U and the voltage line V.

  In the state of FIG. 3A, the U-phase voltage and the V-phase voltage are each 100V, and the voltage between the voltage line U and the voltage line V is 200V. Here, for example, when a current exceeding the reference current value is generated in the voltage line U due to an inrush current or the like, the power conditioner outputs a switching control signal for reducing the U-phase voltage in order to suppress this current. And output to the inverter 20. Thereby, for example, as shown in FIG. 3B, the U-phase voltage temporarily decreases from 100V to 50V. However, since the electric charge is supplied from the capacitor 5C to the capacitors 5A and 5B due to the decrease in the U-phase voltage, for example, as shown in FIG. 3C, the U-phase voltage and the V-phase voltage are 70V and It rises to 120V and settles down. At this time, the voltage between the voltage line U and the voltage line V is 190V.

  In this way, the U-phase voltage decreases and becomes a predetermined reference voltage value (for example, 110 V) or less, but the V-phase voltage increases from the initial state (the state of FIG. 3A) and becomes the reference It becomes more than the voltage value. Therefore, the related art power conditioner has a problem that the operation is stopped when it is determined that a voltage higher than the reference voltage value is generated in the V phase.

  Therefore, in consideration of the above problems, the power conditioner 2 according to the first embodiment stops the autonomous operation by appropriately controlling the voltage output from the inverter 20 according to the following control method. While avoiding, power supply to the load group 300 is maintained.

  In the state of FIG. 4A, the U-phase voltage and the V-phase voltage are each 100V, and the voltage between the voltage line U and the voltage line V is 200V. Here, for example, when a current greater than a predetermined reference current value is generated in the voltage line U due to an inrush current or the like, the power conditioner 2 controls the U-phase voltage and the V-phase voltage to suppress this current. Is generated and output to the inverter 20. Thereby, for example, as shown in FIG. 4B, the U-phase voltage and the V-phase voltage are temporarily reduced from 100 V to 50 V, respectively.

  Here, since the voltage of both the U-phase and the V-phase is lowered, electric charges are supplied from the capacitor 5C to the capacitors 5A and 5B. For example, as shown in FIG. Each voltage rises to 80V. At this time, the voltage between the voltage line U and the voltage line V is 160V.

  Since the power conditioner 2 reduces both the U-phase voltage and the V-phase voltage as described above, both voltages can be made to be equal to or lower than the reference voltage value even if the charge moves. Therefore, the power conditioner 2 according to the first embodiment can maintain the power supply to the load group 300 without stopping the self-sustaining operation like the power conditioners of the related art.

<Configuration of control unit>
FIG. 5 is a schematic diagram showing a configuration of control unit 10 according to the first embodiment. Referring to FIG. 5, control unit 10 includes a voltage input unit 11, a current input unit 12, and a voltage control unit 13.

  The voltage input unit 11 receives input of the voltage value Vu of the U-phase voltage detected by the voltage sensor 51 and the voltage value Vv of the V-phase voltage detected by the voltage sensor 52. The voltage input unit 11 sends the voltage values Vu and Vv to the voltage control unit 13.

  The current input unit 12 receives input of the current value Iu of the U-line current detected by the current sensor 41 and the current value Iv of the V-line current detected by the current sensor 42. The current input unit 12 sends the current values Iu and Iv to the voltage control unit 13.

  In one aspect, voltage control unit 13 controls the voltage output from inverter 20 to the U phase and the V phase based on voltage values Vu, Vv and current values Iu, Iv.

  The voltage control unit 13 reduces the voltage output to the U phase and the V phase when the current value Iu is equal to or greater than the reference current value. Specifically, voltage control unit 13 instructs inverter 20 to make the voltage value of the U-phase voltage smaller than voltage value Vu received by voltage input unit 11. Further, the voltage control unit 13A instructs the inverter 20 to make the voltage value of the V-phase voltage smaller than the voltage value Vv accepted by the voltage control unit 13. Specifically, the voltage control unit 13 generates a switching control signal with a changed duty ratio in order to reduce the U-phase voltage and the V-phase voltage, and outputs the generated switching control signal to the inverter 20.

  Further, the voltage control unit 13 instructs the inverter 20 to make the voltage value of the V-phase voltage smaller than the voltage value Vv accepted by the voltage input unit 11 when the current value Iv is equal to or greater than the reference current value. At the same time, the inverter 20 is instructed to make the voltage value of the U-phase voltage smaller than the voltage value Vu accepted by the voltage input unit 11.

  When the current value Iv or the current value Iv is equal to or higher than a predetermined overcurrent value, the voltage control unit 13 stops the inverter 20 to protect the transistors Q1 to Q6. The reference current value is set to a value smaller than this overcurrent value. As described above, by setting the reference current value to be smaller than the overcurrent value, even when the current value of the voltage line U or the voltage line V is increased, the above-described values are obtained at the stage before these become the overcurrent value. Since voltage control is executed, the inverter 20 can be prevented from stopping. However, the reference current value may be set to an overcurrent value.

(Other aspects of the voltage controller)
The case where the voltage control unit 13 reduces the voltage output to the U phase and the V phase based on the current value received by the current input unit 12 has been described above. However, in another aspect, the voltage control unit 13 may reduce the voltage output to the U phase and the V phase based on the voltage value received by the voltage input unit 11.

  The voltage control unit 13 instructs the inverter 20 to make the voltage value of the U-phase voltage smaller than the voltage value Vu received by the voltage input unit 11 when the voltage value Vu is equal to or higher than the reference voltage value. Further, the voltage control unit 13 instructs the inverter 20 to make the voltage value of the V-phase voltage smaller than the voltage value Vv accepted by the voltage input unit 11. Specifically, the voltage control unit 13 generates a switching control signal with a changed duty ratio in order to decrease the U-phase voltage and the V-phase voltage, and outputs the generated switching control signal to the inverter 20. .

  The voltage control unit 13 instructs the inverter 20 to lower the V-phase voltage below the voltage value Vv and lower the U-phase voltage below the voltage value Vu when the voltage value Vv is equal to or higher than the reference voltage value. To do.

  When voltage value Vu or voltage value Vv is equal to or higher than a predetermined overvoltage value, voltage control unit 13 stops inverter 20 to protect transistors Q1-Q6. The reference voltage value is set to a value smaller than this overvoltage value. By setting the reference voltage value to be smaller than the overvoltage value, even when the voltage value of the voltage line U or the voltage line V increases, the above voltage control is executed at a stage before these become the overcurrent value. Therefore, the stop of the inverter 20 can be prevented. However, the reference voltage value may be set to an overvoltage value. Here, the overvoltage value is, for example, a voltage value according to the graph shown in FIG.

  FIG. 6 is a graph showing an example of the overvoltage value. In the example shown in FIG. 6, the overvoltage value is a voltage value of + 10% of the steady value. For example, the graph shown in FIG. 6 is stored in a memory (not shown) of the control unit 10.

  In this way, the voltage control unit 13 performs control to reduce the voltage output to the U phase and the V phase using the voltage value received from the voltage input unit 11 without using the current value received from the current input unit 12. You can also

<Details of voltage control method>
Here, the voltage control method by the voltage control unit 13 will be described in more detail with reference to FIGS. The voltage control unit 13 generates switching control signals S1 to S6 for controlling the voltage output from the inverter 20 to the U phase and the V phase, and outputs the generated switching control signals S1 to S6 to the inverter 20. To do.

  FIG. 7 is a diagram for explaining the voltage control method (part 1). 7 does not illustrate a part of the configuration of the power conditioner 2 for ease of explanation, it is assumed that these components are configured as shown in FIG. 2 described above.

  Here, a voltage control method when the voltage line U has a higher potential than the neutral line O and the neutral line O has a higher potential than the voltage line V will be described. The voltage control unit 13 can grasp these potential relationships from the voltage values Vu and Vv.

  The voltage control unit 13 reduces the duty ratio of the switching control signals S1 and S2 output to the leg 21 and the switching control signals S5 and S6 output to the leg 23 in order to reduce the voltage output to the U phase and the V phase. The duty ratio is changed, and the duty ratio of the switching control signals S3 and S4 output to the leg 22 is maintained.

  Specifically, in order to reduce the U-phase voltage, the voltage control unit 13 (1) decreases the duty ratio of the switching control signal S1 (for example, 80% → 60%) and shortens the on-time of the transistor Q1. (2) Increasing the duty ratio of the switching control signal S2 (for example, 20% → 40%) extends the on-time of the transistor Q2. The voltage control unit 13 increases the duty ratio of the switching control signal S5 (for example, 20% → 40%) to increase the on-time of the transistor Q5 in order to reduce the V-phase voltage, and (4) The duty ratio of the switching control signal S6 is reduced (for example, 80% → 60%) to shorten the on-time of the transistor Q6. Further, the voltage control unit 13 (5) maintains the duty ratio of the switching control signals S3 and S4 (for example, 50%) and maintains the on-time of the transistors Q3 and Q4.

  The voltage control unit 13 simultaneously executes the controls (1) to (5) to reduce the potential difference between the voltage line U and the neutral line O and the potential difference between the neutral line O and the voltage line V. As a result, the U-phase voltage and the V-phase voltage are lowered.

  FIG. 8 is a diagram for explaining the voltage control method (part 2). As in the case of FIG. 7, the voltage line U has a higher potential than the neutral line O, and the neutral line O has a higher potential than the voltage line V.

  Here, the voltage control unit 13 reduces the voltage output to the U phase and the V phase, the duty ratio of the switching control signals S1 and S2 output to the leg 21, and the switching control signal S3 output to the leg 22. , S4 and the duty ratio of the switching control signals S5, S6 output to the leg 23 are maintained.

  Specifically, the voltage control unit 13 (1) reduces the duty ratio of the switching control signal S1 (for example, 80% → 60%) and (2) the switching control signal S2 in order to reduce the U-phase voltage. Is increased (for example, 20% → 40%). In order to reduce the V-phase voltage, the voltage control unit 13 (3) decreases the duty ratio of the switching control signal S3 (for example, 50% → 40%), and (4) increases the duty ratio of the switching control signal S4. (For example, 50% → 60%). The voltage control unit 13 maintains (5) the duty ratio of the switching control signals S5 and S6 (for example, the duty ratio of S5 is 20% and the duty ratio of S6 is 80%).

  The voltage control unit 13 simultaneously executes the controls (1) to (5) to reduce the potential difference between the voltage line U and the neutral line O and the potential difference between the neutral line O and the voltage line V. As a result, the U-phase voltage and the V-phase voltage are lowered.

  FIG. 9 is a diagram for explaining the voltage control method (part 3). As in the case of FIG. 7, the voltage line U has a higher potential than the neutral line O, and the neutral line O has a higher potential than the voltage line V.

  Here, the voltage control unit 13 reduces the voltage output to the U phase and the V phase, the duty ratio of the switching control signals S3 and S4 output to the leg 22, and the switching control signal S5 output to the leg 23. , S6 and the duty ratio of the switching control signals S1, S2 output to the leg 21 are maintained.

  Specifically, the voltage control unit 13 (1) increases the duty ratio of the switching control signal S3 (for example, 50% → 60%) and (2) the switching control signal S4 in order to reduce the U-phase voltage. Is reduced (for example, 50% → 40%). In order to reduce the V-phase voltage, the voltage control unit 13 (3) increases the duty ratio of the switching control signal S5 (for example, 20% → 40%), and (4) decreases the duty ratio of the switching control signal S6. (For example, 80% → 60%). The voltage control unit 13 maintains (5) the duty ratio of the switching control signals S1 and S2 (for example, the duty ratio of S1 is 80% and the duty ratio of S2 is 20%).

  The voltage control unit 13 simultaneously executes the controls (1) to (5) to reduce the potential difference between the voltage line U and the neutral line O and the potential difference between the neutral line O and the voltage line V. As a result, the U-phase voltage and the V-phase voltage are lowered.

  As described above, the voltage control unit 13 changes the duty ratio of the switching control signal output to two of the three legs 21, 22, and 23, and changes the switching control signal output to the remaining one leg. By maintaining the duty ratio, the U-phase voltage and the V-phase voltage are reduced.

  7 to 9, the voltage line U has a higher potential than the neutral line O and the neutral line O has a higher potential than the voltage line V. However, the voltage line U is higher than the neutral line O. When the potential is low and the neutral line O is lower in potential than the voltage line V, the duty ratios of the switching control signals S1 to S6 may be changed in reverse. For example, referring to FIG. 7, the voltage control unit 13 increases the duty ratio of the switching control signal S1, decreases the duty ratio of the switching control signal S2, decreases the duty ratio of the switching control signal S5, and performs switching. The duty ratio of the control signal S6 is increased and the duty ratio of the switching control signals S3 and S4 is maintained.

  Note that the voltage control unit 13 may change the duty ratio by a preset amount of change, and does not show past results (such as the relationship between the U-phase voltage and the voltage value of the V-phase voltage with respect to the duty ratio). You may memorize | store in memory and may change based on the said performance.

<Processing procedure>
FIG. 10 is a flowchart for illustrating a processing procedure of control unit 10 according to the first embodiment.

  Referring to FIG. 10, control unit 10 obtains current values Iu and Iv detected by current sensors 41 and 42, respectively (step S12). The control unit 10A acquires voltage values Vu and Vv detected by the voltage sensors 51 and 52, respectively (step S14). The processes of steps S12 and S14 may be executed in parallel with each other, or may be executed in a different order.

  The controller 10 determines whether or not the current value Iu or the current value Iv is greater than or equal to the reference current value (step S16). If current value Iu or current value Iv is equal to or greater than the reference current value (YES in step S16), control unit 10 changes the duty ratio of the switching control signal (step S18), and converts the switching control signal to inverter 20 The U-phase voltage and the V-phase voltage are reduced by outputting to (step S20). Specifically, the control unit 10 generates a switching control signal in which the duty ratio is changed by the voltage control method as described above, and outputs the switching control signal to the inverter 20. It is made smaller than the value Vu and the voltage value Vv.

  When current value Iu and current value Iv are both less than the reference current value (NO in step S16), control unit 10 determines that the voltage values of U-phase voltage and V-phase voltage are voltage value Vu and V-phase, respectively, as usual. Control is performed so as to maintain the voltage value Vv (step S22).

  Note that the control unit 10 does not use the current value received from the current input unit 12 but uses the voltage value received from the voltage input unit 11 to decrease the U-phase voltage and the V-phase voltage. The process is omitted. Moreover, the control part 10 determines whether voltage value Vu or voltage value Vv is more than a reference voltage value in said step S16. Then, when the voltage value Vu or the voltage value Vv is equal to or higher than the reference voltage value, the control unit 10 executes the processes of Step S18 and Step S20. When the voltage value Vu and the voltage value Vv are both less than the reference voltage value, In step S22, the process of step S22 is executed.

[Embodiment 2]
As described in the first embodiment, when the U-phase voltage and the V-phase voltage are lowered, the charge moves between the capacitor 5C and the capacitors 5A and 5B. This acts in the direction of increasing the U-phase voltage and the V-phase voltage. Therefore, it can be said that it is desirable to reduce the U-phase voltage and the V-phase voltage in consideration of this charge movement. Therefore, in the second embodiment, a configuration in which the duty ratio of the switching control signal is changed in consideration of the capacitances of the capacitors 5A to 5C will be described.

  It should be noted that the <overall configuration> of the power supply system to which the power conditioner according to the second embodiment is applied is the same except that the power conditioner 2 in the first embodiment is replaced with the power conditioner 2A in FIG. Therefore, detailed description thereof will not be repeated.

<Configuration of the inverter>
FIG. 11 shows a configuration of power conditioner 2A according to the second embodiment. Referring to FIG. 11, power conditioner 2 </ b> A includes control unit 10 </ b> A, inverter 20, current sensors 41 and 42, voltage sensors 51 and 52, reactors L <b> 1 to L <b> 3, and capacitance measurement unit 8. Including. The power conditioner 2 </ b> A is different from the power conditioner 2 in that the control unit 10 in FIG. 2 is replaced with the control unit 10 </ b> A and a point that further includes a capacitance measuring unit 8. Since other configurations are the same, detailed description thereof will not be repeated.

  The capacitance measuring unit 8 includes a capacitance value Cu of a capacitor 5A connected between the voltage line U and the neutral line O, and a capacitor 5B connected between the neutral line O and the voltage line V. The capacitance value Cv of the capacitor 5C and the capacitance value Cuv of the capacitor 5C connected between the voltage line U and the voltage line V are measured, and the measurement result is input to the control unit 10A. As described above, it is assumed that capacitors 5A to 5C are included in load groups 300A to 300C, respectively.

  The control unit 10A includes current values Iu and Iv received from the current sensors 41 and 42, voltage values Vu and Vv received from the voltage sensors 51 and 52, and capacitance values received from the capacitance measurement unit 8, respectively. Based on Cu, Cv, and Cuv, switching control signals S1 to S6 for controlling on / off of the transistors Q1 to Q6 are generated according to a control method to be described later, and the generated switching control signals S1 to S6 are converted into inverters. 20 is output.

<Configuration of control unit>
FIG. 12 is a schematic diagram showing a configuration of a control unit 10A according to the second embodiment. Referring to FIG. 12, control unit 10A includes a voltage input unit 11A, a current input unit 12A, a voltage control unit 13A, and a capacitance input unit 14A. Voltage input unit 11A and current input unit 12A have substantially the same configuration as voltage input unit 11 and current input unit 12 shown in FIG. The voltage control unit 13A has the following functions in addition to the functions of the voltage control unit 13 described above.

  The capacitance input unit 14 </ b> A receives input of capacitances (values) Cu, Cv, Cuv measured by the capacitance measurement unit 8. Capacitance input unit 14A sends capacitance values Cu, Cv, Cuv to voltage control unit 13A.

  When the current value Iu is greater than or equal to the reference current value or the voltage value Vu is greater than or equal to the reference voltage value, the voltage control unit 13A reduces the voltage output to the U phase below the voltage value Vu. At this time, the voltage control unit 13A generates a switching control signal for setting the voltage output to the V phase to the target voltage value based on the voltage values Vu, Vv and the capacitance values Cu, Cv, Cuv, The generated control signal is output to the inverter 20. Hereinafter, the generation method of the switching control signal will be described in detail with reference to FIG.

  FIG. 13 is a diagram for explaining a switching control signal generation method. Specifically, FIG. 13A is a diagram illustrating a voltage relationship between the lines before changing the duty ratio of the switching control signal. FIG. 13B is a diagram illustrating the voltage relationship between the lines after changing the duty ratio of the switching control signal.

  Referring to FIG. 13 (a), before changing the duty ratio of the switching control signal, the voltage value of the voltage (U-phase voltage) between voltage line U and neutral line O is Vu, neutral line O and The voltage value between the voltage lines V (V-phase voltage) is Vv, the voltage value between the voltage line U and the voltage line V is Vu + Vv, and the capacitances of the capacitors 5A to 5C are Cu, Cv, and Cuv, respectively. And

  Here, as described with reference to FIG. 7, in order to reduce the U-phase voltage and the V-phase voltage, the duty ratio of the switching control signals S1 and S2 output to the leg 21 and the switching control signal S5 output to the leg 23 are set. Consider a case in which the duty ratio of the switching control signals S3 and S4 output to the leg 22 is maintained by changing the duty ratio of S6.

  It is assumed that the duty ratio of the switching control signal S1 in the state shown in FIG. 13A (before the duty ratio is changed) is (1 + x) / 2, and the duty ratio of the switching control signal S2 is (1-x) / 2. The duty ratio of the switching control signal S5 is (1-y) / 2, and the duty ratio of the switching control signal S6 is (1 + y) / 2. However, x and y are variables, and 0 <x <1 and 0 <y <1.

  Then, by changing the value of the variable x to t times (where 0 <t <1), as described with reference to FIG. 7, the duty ratio of the switching control signal S1 is reduced and the duty ratio of the switching control signal S2 is decreased. It is assumed that the U-phase voltage is decreased by increasing the voltage.

  Here, changing the value of the variable x to t times (0 <t <1) means changing the capacitance value Cu to the capacitance value Cu / t in the sense that the charge is extracted from the capacitor 5A. It is synonymous with. Therefore, the capacitance value Cu1 of the capacitor 5A after the duty ratio change can be defined as the capacitance value Cu / t. Further, the capacitance of the capacitor 5B after the change of the duty ratio is defined as a capacitance value Cv1 (see FIG. 13B).

  Further, it is assumed that the U-phase voltage changes from the voltage value Vu to the voltage value Vu1 and the V-phase voltage changes from the voltage value Vv to the voltage value Vv1 before and after the change of the duty ratio (see FIG. 13B). The voltage between the voltage line U and the voltage line V changes from the voltage value (Vu + Vv) to the voltage value (Vu1 + Vv1).

  Here, when the charge conservation law is used for the charge (the portion of the region 500 in FIG. 13) accumulated in the lower electrode of the capacitor 5A and the upper electrode of the capacitor 5B before and after the change of the duty ratio, the following equation (1) is obtained. To establish.

  From the equation (1), the voltage value Vu1 can be expressed as the following equation (2).

  Further, when the charge conservation law is used for the charge (the region 600 in FIG. 13) accumulated on the lower electrode of the capacitor 5B and the lower electrode of the capacitor 5C before and after the change of the duty ratio, the following equation (3) is obtained. To establish.

  By substituting the voltage value Vu1 represented by the equation (2) into the equation (3) and arranging it, the capacitance value Cv1 can be expressed as the following equation (4).

  Here, changing the value of the variable y to s times (0 <s <1) means changing the capacitance value Cv to the capacitance value Cv / s in the sense that the charge is extracted from the capacitor 5B. It is synonymous with. Therefore, since Cv1 = Cv / s, the following equation (5) is established.

  Accordingly, it is understood that s may be set as shown in Expression (5) in order to set the voltage value of the V-phase voltage to the voltage value Vv1. Therefore, when the value of the variable x is changed to t times (0 <t <1) and the U-phase voltage is decreased, the voltage value of the V-phase voltage is desired to be smaller than the overvoltage value Vz. What is necessary is just to set s so that the following formula | equation (6) which substituted Vv1 = Vz to Formula (5) may be materialized.

  Thereby, the voltage control unit 13A can prevent the inverter 20 from being stopped due to the V-phase voltage being equal to or higher than the overvoltage value. Further, the voltage control unit 13A outputs the switching control signal in which s is set so that the target voltage value of the V-phase voltage is in the vicinity of the overvoltage value Vz to the inverter 20, thereby reducing the V-phase voltage more than necessary. Can be prevented. Thereby, the power conditioner 2 </ b> A can supply as much power as possible to the load group 300.

  Further, when it is desired to maintain the V-phase voltage when reducing the U-phase voltage (that is, when it is not desired to change the V-phase voltage before and after changing the duty ratio), Vv1 = Vv is substituted into equation (5). What is necessary is just to set s as shown in the following formula | equation (7).

  As a result, the voltage control unit 13A can suppress the change in the V-phase voltage even when the U-phase voltage is decreased. Therefore, the power conditioner 2A can supply stable power to the load group 300B connected to the V phase.

  Furthermore, when the U-phase current is equal to or higher than the reference current value or when the U-phase voltage is equal to or higher than the reference voltage value, the U-phase voltage needs to be relatively greatly reduced, but the V-phase voltage is decreased as much as the U-phase voltage. It does not have to be. Therefore, the voltage control unit 13A includes the inverter 20 so that the amount of decrease in the V-phase voltage (= Vv−Vv1) is smaller than the amount of decrease in the U-phase voltage (= Vu−Vu1) (Vv−Vv1 <Vu−Vu1). You may instruct.

  Specifically, since the voltage values Vu, Vv received from the voltage input unit 11A and the capacitance values Cu, Cv, Cuv received from the capacitance input unit 14A are known values, Equations (2) and (4) are obtained. By using this, the relationship between t for satisfying Vv−Vv1 <Vu−Vu1 and the voltage value Vv1 can be understood. Since the voltage value Vv1 can be expressed by t and s according to the equation (5), the relationship between t and s for satisfying Vv−Vv1 <Vu−Vu1 is obtained as a result. The voltage control unit 13A generates a switching control signal based on t and s satisfying this relationship and outputs the switching control signal to the inverter 20, so that the decrease amount of the V-phase voltage is smaller than the decrease amount of the U-phase voltage. To.

<Processing procedure>
FIG. 14 is a flowchart for illustrating a processing procedure of control unit 10A according to the second embodiment.

  Referring to FIG. 14, control unit 10A obtains current values Iu and Iv detected by current sensors 41 and 42, respectively (step S32). The control unit 10A acquires voltage values Vu and Vv detected by the voltage sensors 51 and 52, respectively (step S34). The controller 10A acquires the capacitance values Cu, Cv, Cuv respectively measured by the capacitance measuring unit 8 (step S36). The processes of steps S32, S34, and S36 may be executed in parallel with each other, or may be executed in a different order.

  The controller 10A determines whether or not the current value Iu or the current value Iv is equal to or greater than the reference current value (step S38). When both current value Iu and current value Iv are less than the reference current value (NO in step S38), control unit 10A determines that the voltage values of the voltages output to the U phase and V phase are voltage value Vu and A switching control signal is output to the inverter 20 so as to maintain the voltage value Vv (step S44).

  When current value Iu or current value Iv is greater than or equal to the reference current value (YES in step S38), control unit 10A determines the switching control signal based on voltage values Vu, Vv and capacitance values Cu, Cv, Cuv. The duty ratio is changed (step S40).

  Specifically, when the current value Iu is equal to or higher than the reference current value, the control unit 10A determines the switching control signal output to the leg that controls the U-phase voltage in order to reduce the U-phase voltage. The duty ratio is changed (the value of the variable x is increased t times as described above). At the same time, the control unit 10A changes the duty ratio of the switching control signal output to the leg that controls the V-phase voltage by using Equation (5) so that the V-phase voltage becomes the target voltage value. (As described above, the value of the variable y is multiplied by s). When the current value Iv is equal to or greater than the reference current value, the control unit 10A performs this process by replacing the U phase and the V phase.

  Then, control unit 10A outputs a switching control signal with a changed duty ratio to inverter 20, thereby lowering (or maintaining) the V-phase voltage while lowering the U-phase voltage (step S42).

  As with the control unit 10, the control unit 10A does not use the current value received from the current input unit 12A, but uses the voltage value received from the voltage input unit 11A to output the voltage output to the U phase and the V phase. It may be lowered.

[Embodiment 3]
In the third embodiment, a voltage control method when the inverter has two legs will be described with reference to FIG. The power conditioner 2 according to the first embodiment includes an inverter 20 having three legs 21, 22, and 23. However, power conditioner 2 </ b> B according to the third embodiment includes inverter 20 </ b> B having two legs 21 and 23 instead of inverter 20.

  Note that <general configuration> of the power supply system to which the power conditioner according to the third embodiment is applied is the same except that the power conditioner 2 in the first embodiment is replaced with the power conditioner 2B in FIG. Therefore, detailed description thereof will not be repeated.

  FIG. 15 shows a configuration of power conditioner 2B according to the third embodiment. Since the configuration other than inverter 20B of power conditioner 2B according to the third embodiment is the same as the configuration of power conditioner 2 described above, detailed description thereof will not be repeated. Further, since inverter 20B does not have leg 22, in the third embodiment, control unit 10 (voltage control unit 13) does not output switching control signals S3 and S4.

  Referring to FIG. 15, inverter 20 </ b> B includes leg 21 and leg 23, and capacitors 71 and 72 connected in parallel to each other. Capacitors 71 and 72 are connected in series between positive bus PL and negative bus SL forming DC bus 150. An intermediate point between the capacitor 71 and the capacitor 72 is connected to the terminal 202 via the reactor L2.

  Hereinafter, the voltage control method in the third embodiment will be described with reference to FIG. 7, the voltage line U has a higher potential than the neutral line O, and the neutral line O has a higher potential than the voltage line V.

  The control unit 10 (voltage control unit 13) is configured to switch the duty ratio of the switching control signals S1 and S2 output to the leg 21 and the switching control output to the leg 23 in order to reduce the voltage output to the U phase and the V phase. The duty ratio of the signals S5 and S6 is changed.

  Specifically, the voltage control unit 13 (1) reduces the duty ratio of the switching control signal S1 (for example, 80% → 60%) and (2) the switching control signal S2 in order to reduce the U-phase voltage. Is increased (for example, 20% → 40%). In order to reduce the V-phase voltage, the voltage control unit 13 increases (3) the duty ratio of the switching control signal S5 (for example, 20% → 40%), and (4) sets the duty ratio of the switching control signal S6. Decrease (for example, 80% → 60%).

  The voltage control unit 13 simultaneously executes the controls (1) to (4) to reduce the potential difference between the voltage line U and the neutral line O and the potential difference between the neutral line O and the voltage line V. As a result, the U-phase voltage and the V-phase voltage are lowered.

  In FIG. 15, the voltage line U has a higher potential than the neutral line O and the neutral line O has a higher potential than the voltage line V. However, the voltage line U has a higher potential than the neutral line O. When the potential of the neutral line O is lower than that of the voltage line V, the duty ratios of the switching control signals S1, S2, S5, and S6 may be changed in reverse.

[Embodiment 4]
In the fourth embodiment, a voltage control method in the case where the power conditioner includes two inverters will be described.

  FIG. 16 is a diagram showing a configuration of a power conditioner 2C according to the fourth embodiment. Although not shown, the power conditioner 2C is connected to the AC power system 6 through the power line 3 in the same manner as in FIG. 1, and supplies power to the load groups 300A, 300B, and 300C.

  Referring to FIG. 16, power conditioner 2C includes control unit 10C, inverters 30 and 35, current sensors 41 and 42, voltage sensors 51 and 52, reactors L1 to L4, and terminals 201 to 207. Including.

  The inverter 30 converts the DC power supplied from the DC power supply 4 via the DC bus 150 into AC power in accordance with the switching control signals S1 to S4 from the control unit 10C, and the AC power obtained by the conversion is converted. Output to U phase.

  Inverter 30 includes a leg 21 and a leg 22 connected in parallel to each other. In leg 21, transistors Q1 and Q2 are connected in series between positive bus PL and negative bus SL forming DC bus 150. An intermediate point between transistor Q1 and transistor Q2 is connected to terminal 201 via reactor L1. In leg 22, transistors Q3 and Q4 are connected in series between positive bus PL and negative bus SL. An intermediate point between transistor Q3 and transistor Q4 is connected to terminal 202 via reactor L2.

  The inverter 35 converts the DC power supplied from the DC power supply 4A via the DC bus 160 into AC power according to the switching control signals S5 to S8 from the control unit 10C, and the AC power obtained by the conversion is converted. Output to V phase.

  Inverter 35 includes a leg 23 and a leg 24 connected in parallel to each other. Leg 24 includes an upper arm (transistor Q7 and diode D7) and a lower arm (transistor Q8 and diode D8).

  In leg 23, transistors Q5 and Q6 are connected in series between positive bus PL and negative bus SL forming DC bus 160. An intermediate point between transistor Q5 and transistor Q6 is connected to terminal 202 via reactor L3. In leg 24, transistors Q7 and Q8 are connected in series between positive bus PL and negative bus SL forming DC bus 160. An intermediate point between transistor Q7 and transistor Q8 is connected to terminal 203 via reactor L4.

<Configuration of control unit>
FIG. 17 is a schematic diagram showing a configuration of a control unit 10C according to the fourth embodiment. Referring to FIG. 17, control unit 10C includes a voltage input unit 11C, a current input unit 12C, and a voltage control unit 13C. The voltage input unit 11C and the current input unit 12C have substantially the same configurations as the voltage input unit 11 and the current input unit 12 shown in FIG.

  The voltage control unit 13 </ b> C has the same function as the voltage control unit 13 and controls the U-phase voltage and the V-phase voltage in the same manner as the voltage control unit 13. However, the voltage control unit 13 generates the switching control signals S1 to S6 and outputs them to the inverter 20 to control the U-phase voltage and the V-phase voltage, but the voltage control unit 13C generates the switching control signals S1 to S8. Then, the U-phase voltage and the V-phase voltage are controlled by outputting them to the inverters 30 and 35.

<Voltage control method>
Hereinafter, the voltage control method according to the fourth embodiment will be described with reference to FIG. Specifically, a voltage control method when the voltage control unit 13C reduces the voltage output to the U phase and the V phase will be described. 7, the voltage line U has a higher potential than the neutral line O, and the neutral line O has a higher potential than the voltage line V.

  The voltage control unit 13C changes the duty ratios of the switching control signals S1 to S8 output to the legs 21 to 24 in order to reduce the U-phase voltage and the V-phase voltage.

  Specifically, the voltage control unit 13C reduces (1) the duty ratio of the switching control signals S1 and S4 (for example, 80% → 60%) and (2) switching control in order to reduce the U-phase voltage. The duty ratio of the signals S2 and S3 is increased (for example, 20% → 40%). In order to reduce the V-phase voltage, the voltage controller 13C reduces (3) the duty ratio of the switching control signals S5 and S8 (for example, 80% → 60%), and (4) the switching control signals S6 and S7. Increase the duty ratio (for example, 20% → 40%).

  The voltage control unit 13C simultaneously executes the controls (1) to (4) to reduce the potential difference between the voltage line U and the neutral line O and the potential difference between the neutral line O and the voltage line V. As a result, the U-phase voltage and the V-phase voltage are lowered.

  In FIG. 16, the voltage line U has a higher potential than the neutral line O and the neutral line O has a higher potential than the voltage line V. However, the voltage line U has a higher potential than the neutral line O. When the potential of the neutral line O is lower than that of the voltage line V, the duty ratio of the switching control signals S1 and S4 is increased, the duty ratio of the switching control signals S2 and S3 is decreased, and the switching control signal S5 , S8 may be increased and the duty ratio of the switching control signals S6, S7 may be decreased.

[Other embodiments]
In the above-described embodiment, the case where the current sensors 41 and 42, the voltage sensors 51 and 52, and the capacitance measuring unit 8 are provided in the power conditioner has been described, but these are provided outside the power conditioner. It may be.

  Capacitors 5A to 5C may be combined capacitances that take into account the capacitance of the capacitors provided in the power conditioner. That is, the electrostatic capacity of the capacitor 5A is a combined capacity of all the capacitors connected between the voltage line U and the neutral line O, and the electrostatic capacity of the capacitor 5B is between the neutral line O and the voltage line V. The capacitance of the capacitor 5C may be the combined capacitance of all the capacitors connected between the voltage line U and the voltage line V.

[Summary]
Embodiments of the present invention can be summarized as follows.

  (1) A power conditioner 2 connected to a single-phase three-wire power line 3 having a voltage line U, a voltage line V, and a neutral line O, and a DC power supply 4 is configured to use the DC power of the DC power supply 4 simply. The inverter 20 which converts into phase 3 wire type alternating current power and the control part 10 which controls the inverter 20 are provided. The control unit 10 receives a U-phase voltage value Vu composed of the voltage line U and the neutral line O and a V-phase voltage value Vv composed of the voltage line V and the neutral line O. Voltage control for controlling the voltage output from the inverter 20 to the U phase and the V phase based on the current input unit 12 that receives the current value Iu of the voltage line U, the voltage values Vu, Vv, and the current value Iu. Part 13. When the current value Iu is equal to or higher than the reference current value, the voltage control unit 13 reduces the voltage output to the U phase below the voltage value Vu and reduces the voltage output to the V phase below the voltage value Vv. The inverter 20 is instructed to do so.

  According to the said structure, the stop of the independent operation of the power conditioner 2 which is not intended can be prevented. Therefore, power supply to the load group 300 can be maintained.

  (2) The voltage control unit 13 stops the inverter 20 when the current value Iu becomes equal to or higher than the overcurrent value. The reference current value is smaller than the overcurrent value.

  According to the above configuration, even when the current value of one voltage line increases, voltage reduction control is executed at a stage before these current values become overcurrent values, so that the inverter 20 can be more effectively prevented from stopping. it can.

  (3) The power conditioner 2 connected to the single-phase three-wire power line 3 having the voltage line U and the voltage line V and the neutral line O and the direct-current power supply 4 is configured to supply the direct-current power of the direct-current power supply 4 The inverter 20 which converts into a phase 3 wire type alternating current power and the control part 10 which controls the inverter 20 are provided. The control unit 10 receives a U-phase voltage value Vu composed of the voltage line U and the neutral line O and a V-phase voltage value Vv composed of the voltage line V and the neutral line O. And a voltage control unit 13 that controls the voltage output from the inverter 20 to the U phase and the V phase based on the voltage values Vu and Vv. When the voltage value Vu is equal to or higher than the reference voltage value, the voltage control unit 13 reduces the voltage output to the U phase below the reference voltage value and sets the voltage output to the V phase to the voltage value Vv or less. Instruct the inverter 20 as follows.

  According to the said structure, the stop of the independent operation of the power conditioner 2 which is not intended can be prevented. Therefore, power supply to the load group 300 can be maintained.

  (4) The voltage control unit 13 stops the inverter 20 when the voltage value Vu or the voltage value Vv is equal to or higher than the overvoltage value. The reference voltage value is smaller than the overvoltage value.

  According to the above configuration, even when the voltage value of one phase increases, voltage reduction control is executed at a stage before these voltage values become overvoltage values, so that the inverter 20 can be more effectively prevented from stopping.

  (5) The controller 10A controls the capacitance value Cu of the capacitor 5A connected between the voltage line U and the neutral line O and the static value of the capacitor 5B connected between the voltage line V and the neutral line O. It further includes a capacitance input unit 14A that receives the capacitance value Cv and the capacitance value Cuv of the capacitor 5C connected between the voltage line U and the voltage line V. When the voltage control unit 13A reduces the voltage output to the U phase below the voltage value Vu, the voltage control unit 13A determines the voltage output to the V phase based on the voltage values Vu, Vv and the capacitance values Cu, Cv, Cuv. Switching control signals S <b> 1 to S <b> 6 for setting the target voltage value are generated, and the generated switching control signals S <b> 1 to S <b> 6 are output to the inverter 20.

  According to the above configuration, the U-phase voltage and the V-phase voltage can be reduced in consideration of the movement of charges, so that the U-phase voltage and the V-phase voltage can be controlled with higher accuracy.

(6) The target voltage value is a voltage value received by the voltage input unit 11A.
According to the above configuration, for example, even when the phase (for example, the U-phase voltage) that has become equal to or higher than the reference current value or the reference voltage value is reduced, the change in the voltage of the other phase (for example, the V-phase) is suppressed. be able to. Therefore, the power conditioner 2A can supply stable power to the load group 300B connected to the V phase.

  (7) The voltage control unit 13 instructs the inverter 20 so that the amount of decrease in the voltage output to the V phase is smaller than the amount of decrease in the voltage output to the U phase.

  According to the above configuration, a large amount of power can be supplied to the load group 300B by suppressing the amount of decrease in the V-phase voltage on the side that is not equal to or higher than the reference current value or the reference voltage value.

  The configuration illustrated as the above-described embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part of the configuration is omitted without departing from the gist of the present invention. It is also possible to change the configuration.

  In the above-described embodiment, the processing and configuration described in the other embodiments may be adopted as appropriate.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2, 2A, 2B, 2C Power conditioner, 3 Power line, 4, 4A DC power supply, 5A, 5B, 5C, 71, 72 Capacitor, 6 AC power system, 8 Capacitance measuring unit, 10, 10A, 10C Control unit 11, 11A, 11C Voltage input unit, 12, 12A, 12C Current input unit, 13, 13A, 13C Voltage control unit, 14A Capacity input unit, 20, 20B, 30, 35 Inverter, 21, 22, 23, 24 leg 41, 42 Current sensor, 51, 52 Voltage sensor, 150, 160 DC bus, 201, 202, 203, 204, 205, 207 terminal, 300A, 300B, 300C load group, 500, 600 region, D1-D8 diode, L1, L2, L3, L4 reactors, Q1-Q8 transistors.

Claims (5)

A power conditioner connected to a single-phase three-wire power line having first and second voltage lines and a neutral line, and a DC power source,
An inverter that converts DC power of the DC power source into single-phase, three-wire AC power;
A control unit for controlling the inverter,
The controller is
The first voltage value of the first phase composed of the first voltage line and the neutral line, and the second voltage value of the second phase composed of the second voltage line and the neutral line Voltage input means for receiving
Current input means for receiving a first current value of the first voltage line;
A voltage control unit that controls a voltage output from the inverter to the first phase and the second phase based on the first and second voltage values and the first current value;
The voltage control unit lowers the voltage output to the first phase below the first voltage value and outputs to the second phase when the first current value is greater than or equal to a reference current value. A power conditioner that instructs the inverter to reduce the voltage to be applied to the second voltage value or less. The voltage control unit stops the inverter when the first current value becomes an overcurrent value or more,
The power conditioner according to claim 1, wherein the reference current value is smaller than the overcurrent value. A power conditioner connected to a single-phase three-wire power line having first and second voltage lines and a neutral line, and a DC power source,
An inverter that converts DC power of the DC power source into single-phase, three-wire AC power;
A control unit for controlling the inverter,
The controller is
The first voltage value of the first phase composed of the first voltage line and the neutral line, and the second voltage value of the second phase composed of the second voltage line and the neutral line Voltage input means for receiving
A voltage control unit configured to control a voltage output from the inverter to the first phase and the second phase based on the first and second voltage values;
The voltage control unit lowers the voltage output to the first phase below the reference voltage value and outputs to the second phase when the first voltage value is equal to or higher than a reference voltage value. A power conditioner that instructs the inverter to make a voltage equal to or lower than the second voltage value. The voltage control unit stops the inverter when the first or second voltage value is equal to or higher than an overvoltage value,
The power conditioner according to claim 3, wherein the reference voltage value is smaller than the overvoltage value.   The said voltage control part instruct | indicates to the said inverter so that the fall amount of the voltage output to the said 2nd phase may become smaller than the fall amount of the voltage output to the said 1st phase. The power conditioner of Claim 1.

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