JP6468593B2 - Power storage system - Google Patents

Description

  The present invention relates to a power storage system using a plurality of storage batteries.

  By using a power storage system that can store and discharge power, it is possible to supply power to the load device for a certain period even during a power failure. In general, in a power storage system, when AC power is supplied from a commercial power source to a load device, the AC power is branched and received, converted into DC power via a converter, and then charged to a storage battery by a charging circuit. . When a power failure occurs, the power storage system converts the power charged in the storage battery into AC power using an inverter, and supplies AC power to the load device. For the load device, a changeover switch or the like is used so that power is supplied from a commercial power source during power transmission and from a storage battery during a power failure. In addition, in order to be able to supply power without delay when a power failure occurs, the above-described inverter needs to be constantly driven.

  When the power storage system includes a plurality of storage batteries, the amount of stored power can be increased. For example, Patent Document 1 discloses a power storage system that can select a storage battery to be discharged by detecting the state of each storage battery. More specifically, this power storage system detects and sequentially updates information such as the state of charge of each storage battery and the presence / absence of a failure, and in the event of a power failure, the redundant control mechanism selects a storage battery to discharge based on this information and the power demand of the load. At this time, the power storage system detects the power demand in the load device by providing a load output detection mechanism between the inverter and the changeover switch on the path for supplying power from the storage battery to the load device.

Japanese Patent Laid-Open No. 11-146575

  By the way, a commercial power supply generally supplies power with a rated current of a contracted amperage. The storage battery, charging circuit, inverter, and the like included in the above-described power storage system to which this power is supplied consumes power during charging. For this reason, the load device to which power from the commercial power source is similarly supplied cannot receive the power of the rated current as it is, and receives the power by the current obtained by subtracting the internal current consumption of the power storage system from the rated current. Further, as the capacity of the power storage system is increased, the number of storage batteries is increased, whereby the internal current consumption is further increased, and the current that can be supplied to the load device is further decreased. For this reason, even if the current required by the load device is equal to or less than the rated current, the current that can be supplied to the load device may not be sufficient.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a power storage system that reduces a possibility that a current supplied to a load device is insufficient due to an internal current consumption.

<First Aspect of the Present Invention>
A first aspect of the present invention includes a plurality of storage batteries, a charging unit that converts AC power supplied from a commercial AC power source into DC power and charges the plurality of storage batteries, and a DC that is supplied from the plurality of storage batteries. A power converter for converting power into AC power; a diode connected in parallel to the storage battery and capable of supplying DC power from the charging unit to the power converter; and AC power supplied from a commercial AC power source or An output unit that selectively outputs any of the AC power output by the power conversion device to a load device; a current detection unit that detects an output current of the output unit; and a control unit, the control unit comprising: While the commercial AC power supply blackout is detected, the output unit is controlled so that the AC power output from the power converter is output to the load device, and the commercial AC power supply blackout is not detected. The number of storage batteries that allow charging of the plurality of storage batteries according to the magnitude of the output current of the output section, provided that the output current of the output section is greater than or equal to a first current threshold and less than a second current threshold. Is increased or decreased, and charging is prohibited for all the storage batteries of the plurality of storage batteries on the condition that the output current of the output unit is equal to or greater than the second current threshold.

  AC power supplied from a commercial AC power source is converted into DC power by a charging unit and then charged to a plurality of storage batteries. Moreover, the DC power discharged from the plurality of storage batteries is converted into AC power by the power converter. The output unit selectively supplies either AC power from the power converter or AC power supplied from a commercial AC power source to the load device. A current detection unit between the output unit and the load device detects a current supplied from the output unit to the load device.

  The control unit monitors a power failure of the commercial AC power supply, and performs control to switch the output unit so that power can be supplied from the power conversion device to the load device when the power failure occurs. Further, the control unit maintains the output unit in a state where power is supplied from the commercial AC power source to the load device during a normal time when no power failure occurs.

  During normal times, the control unit checks whether the output current detected by the current detector is equal to or greater than the first current threshold and less than the second current threshold. Here, the first current threshold value is a current threshold value set lower than a current value obtained by subtracting the total internal current consumption of the power storage system from the rated current of the commercial power source. The second current threshold value is a current threshold value set equal to the current value obtained by adding the current consumed when all the storage batteries are charged simultaneously to the first current threshold value.

  Then, the control unit is provided with a storage battery that permits charging when the output current increases, provided that the value of the output current detected by the current detector is within a range that is greater than or equal to the first current threshold and less than the second current threshold. When the number is reduced and the output current is reduced, control is performed to increase the number of storage batteries that are allowed to be charged. Further, when the value of the output current becomes equal to or greater than the second current threshold, charging of all the storage batteries is prohibited.

  With this control by the control unit, the internal current consumption in the power storage system can be increased or decreased in accordance with the increase or decrease in the output current supplied to the load device, and the current that can be supplied to the load device as the current required by the load device increases. Can be raised step by step.

  Thereby, according to the 1st aspect of this invention, the effect that the electrical storage system which can reduce the possibility that the electric current supplied to a load apparatus by the internal consumption current may run short can be provided.

<Second Aspect of the Present Invention>
According to a second aspect of the present invention, in the first aspect of the present invention described above, while the control unit does not detect a power failure of the commercial AC power supply, the output current of the output unit is equal to or greater than the first current threshold. A storage system that selectively switches the storage batteries that allow charging of the plurality of storage batteries in order under the condition that the storage battery is less than a second current threshold.

  When the output current of the output unit is greater than or equal to the first current threshold and less than the second current threshold, the control unit increases or decreases the number of storage batteries that are allowed to be charged according to the magnitude of the current. At this time, the control unit performs control so that charging is not permitted only to a specific storage battery by selectively sequentially replacing storage batteries that permit charging. Thereby, a plurality of storage batteries can be charged evenly.

  Thereby, according to the 2nd mode of the present invention, in addition to the operation effect by the 1st mode of the present invention mentioned above, since a plurality of storage batteries with which the power storage system is provided can be charged equally, The effect of prolonging the product life can be obtained.

<Third Aspect of the Present Invention>
According to a third aspect of the present invention, in the first or second aspect of the present invention described above, the charging unit corresponds to each storage battery of the plurality of storage batteries, and operates with AC power supplied from a commercial AC power source. Including a plurality of charging circuits, the control unit is provided that the output current of the output unit is greater than or equal to the second current threshold and less than the third current threshold while the power failure of the commercial AC power supply is not detected. The number of charging circuits that supply AC power from the commercial AC power supply of the plurality of charging circuits is increased or decreased according to the magnitude of the output current of the output unit, and the output current of the output unit is equal to or greater than the third current threshold value. This is a power storage system that cuts off all the supply of AC power from a commercial AC power source to the plurality of charging circuits on the condition that

  The charging unit included in the power storage system includes a plurality of charging circuits that operate with a commercial AC power supply. Each charging circuit converts AC power supplied from a commercial AC power source into DC power, and charges a storage battery corresponding to each charging circuit.

  During normal times when no power failure has occurred, the control unit checks whether the output current detected by the current detector is greater than or equal to the second current threshold and less than the third current threshold. Here, the third current threshold value is a current threshold value set equal to the current value obtained by adding the current consumed by all the charging circuits of the power storage system to the second current threshold value.

  The control unit supplies power from the commercial AC power source when the output current increases on condition that the value of the output current detected by the current detection unit is equal to or greater than the second current threshold and less than the third current threshold. When the number of charging circuits is reduced and the output current decreases, control is performed to increase the number of charging circuits that supply power from the commercial AC power supply. Further, when the value of the output current becomes equal to or greater than the third current threshold, the supply of AC power to all the charging circuits is cut off.

  Even if charging of all the storage batteries is prohibited due to this control by the control unit, even if the current required by the load device increases, the internal current consumption in the power storage system is adjusted according to the increase or decrease in the output current supplied to the load device. As the current required by the load device increases, the current that can be supplied to the load device can be increased stepwise.

  Thus, according to the third aspect of the present invention, it is possible to provide a power storage system that further reduces the possibility that the current supplied to the load device due to the internal current consumption is insufficient as compared with the first or second aspect of the present invention. The effect that it can be obtained.

<Fourth aspect of the present invention>
According to a fourth aspect of the present invention, a plurality of storage batteries, a charging unit that converts AC power supplied from a commercial AC power source into DC power and charges the plurality of storage batteries, and DC supplied from the plurality of storage batteries. A power converter for converting power into AC power; a diode connected in parallel to the storage battery and capable of supplying DC power from the charging unit to the power converter; and AC power supplied from a commercial AC power source or An output unit that selectively outputs any of the AC power output by the power conversion device to a load device; a current detection unit that detects an output current of the output unit; and a control unit, wherein the charging unit is A plurality of charging circuits corresponding to each storage battery of the plurality of storage batteries and operating with AC power supplied from a commercial AC power source, while the control unit detects a power failure of the commercial AC power source, While the output unit is controlled so that AC power output from the power converter is output to the load device, and a power failure of the commercial AC power supply is not detected, the output current of the output unit is equal to or higher than the lower limit current threshold The number of charging circuits that supply AC power from the commercial AC power supply of the plurality of charging circuits is increased or decreased according to the magnitude of the output current of the output unit, provided that the output unit A power storage system that cuts off all AC power from a commercial AC power source to the plurality of charging circuits on condition that an output current is equal to or greater than the upper limit current threshold.

  The AC power supplied from the commercial AC power supply is converted into DC power by the charging unit, and then the plurality of storage batteries are charged. Moreover, the DC power discharged from the plurality of storage batteries is converted into AC power by the power converter. The output unit selectively supplies either AC power from the power converter or AC power supplied from a commercial AC power source to the load device. A current detection unit between the output unit and the load device detects a current supplied to the load device.

  The control unit monitors a power failure of the commercial AC power supply, and performs control to switch the output unit so that power can be supplied from the power conversion device to the load device when the power failure occurs. Further, the control unit maintains the output unit in a state where power is supplied from the commercial AC power source to the load device during a normal time when no power failure occurs.

  During normal times, the control unit checks whether the output current detected by the current detection unit is greater than or equal to the lower limit current threshold and less than the upper limit current threshold. Here, the lower limit current threshold value is a current threshold value set lower than a current value obtained by subtracting the total internal current consumption of the power storage system from the rated current of the commercial power source. The upper limit current threshold is a current threshold set equal to the current value obtained by adding the current consumed when all the storage batteries are charged simultaneously and the current consumed by all the charging circuits to the lower limit current threshold.

  The control unit reduces the number of charging circuits that supply power from the commercial AC power source when the output current increases, provided that the value of the output current detected by the current detector is within this range, and outputs When the current decreases, control is performed to increase the number of charging circuits that supply power from the commercial AC power supply. Further, when the value of the output current becomes equal to or greater than the upper limit current threshold, the supply of AC power to all charging circuits is cut off.

  With this control by the control unit, the internal current consumption in the power storage system can be increased or decreased in accordance with the increase or decrease in the output current supplied to the load device, and the current that can be supplied to the load device as the current required by the load device increases. Can be raised step by step.

  According to the fourth aspect of the present invention, it is possible to provide an operational effect that it is possible to provide a power storage system that can reduce the possibility that the current supplied to the load device is insufficient due to the internal current consumption.

<Fifth aspect of the present invention>
According to a fifth aspect of the present invention, in the above-described fourth aspect of the present invention, while the control unit does not detect a power failure of the commercial AC power supply, the output current of the output unit is equal to or higher than a lower limit current threshold value. A power storage system that selectively and sequentially switches charging circuits that supply AC power from commercial AC power supplies of the plurality of charging circuits on condition that the current is less than a current threshold.

  When the output current of the output unit is greater than or equal to the lower limit current threshold and less than the upper limit current threshold, the control unit increases or decreases the number of storage batteries that allow charging according to the magnitude of the current. At this time, the control unit performs control so that only a specific storage battery is not allowed to be charged by selectively switching a charging circuit that supplies AC power from a commercial AC power supply. Thereby, a plurality of storage batteries can be charged evenly.

  Thereby, according to the 5th aspect of this invention, since the some storage battery with which the said electrical storage system is equipped can be charged equally in addition to the effect by the 4th aspect of this invention mentioned above, The effect of prolonging the product life can be obtained.

<Sixth aspect of the present invention>
According to a sixth aspect of the present invention, in any one of the third to fifth aspects of the present invention described above, the control unit does not detect a power failure of the commercial AC power supply. In a state where commercial AC power is supplied, the power converter operates with DC power output from the charging circuit to which the commercial AC power is supplied, and AC power from the commercial AC power to the plurality of charging circuits is In the state where all the supply is cut off, the power conversion device operates with the DC power supplied from the plurality of storage batteries.

  During normal times when the control unit has not detected a power failure of the commercial AC power supply, if the AC power of the commercial power supply is supplied to any of the multiple charging circuits, the operation of the power converter is performed using the DC power output by the charging circuit. Can be maintained. Moreover, even if all the power supply of the commercial AC power supply to a some charging circuit is interrupted | blocked, since direct-current power is supplied to a power converter device from a some storage battery, operation | movement of a power converter device can be maintained.

  Therefore, according to the sixth aspect of the present invention, in any one of the third to fifth aspects of the present invention described above, the operation of the power conversion device is maintained even when all the power supply to all the charging circuits is cut off. Therefore, AC power can be supplied to the load device without delay when a power failure occurs.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage system which reduces the possibility that the electric current supplied to a load apparatus may be insufficient by internal consumption current can be provided.

It is a circuit diagram which shows the structure of the electrical storage system which concerns on this invention. It is a relationship figure of the output current and input current of the electrical storage system concerning the 1st example of the present invention, and the change of input current when controlling internal consumption current is shown by the thick line. FIG. 6 is a relationship diagram between an output current and an input current of a power storage system according to a second embodiment of the present invention, and shows a change in the input current when the internal current consumption is controlled by a bold line.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First embodiment>
FIG. 1 is a circuit diagram showing a configuration of a power storage system 1 according to the present invention.

  The power storage system 1 is connected to the commercial power source 2 and receives AC power from the commercial power source 2 during normal times when no power failure occurs. The power storage system 1 is connected to the load device 3 and supplies AC power to the load device 3.

  The power storage system 1 includes a plurality of storage batteries B1 to B3, a charging unit 12, an inverter 13 as a “power conversion device”, a switch 14 as an “output unit”, a current detection unit 15, a control unit 16, an internal power supply 17, and a plurality of Diodes D1 to D6 are provided. Charging unit 12 includes a plurality of charging circuits 121 to 123.

  In the present embodiment, the power storage system 1 will be described with a configuration including three storage batteries B1 to B3 and three charging circuits 121 to 123. However, this is only an example, and the number of each is not limited thereto.

  The charging circuits 121 to 123 are supplied with AC power from the commercial power source 2. Charging circuit 121 includes a converter circuit (not shown) that converts AC power into DC power, and charges corresponding storage battery B1. The output of the charging circuit 121 is also connected to the inverter 13 through the diode D1 so that DC power can be supplied to the inverter 13 even when the storage battery B1 is fully charged or charging is prohibited. The electric power charged in the storage battery B1 is supplied to the inverter 13 through the diode D2. The diodes D1 and D2 are provided to prevent the storage battery B1 from being charged with the power of the other storage batteries B2 and B3.

  Charging circuit 122 includes a converter circuit (not shown) that converts AC power into DC power, and charges corresponding storage battery B2. The output of the charging circuit 122 is also connected to the inverter 13 through the diode D3 so that DC power can be supplied to the inverter 13 even when the storage battery B2 is fully charged or charging is prohibited. The electric power charged in the storage battery B2 is supplied to the inverter 13 through the diode D4. The diodes D3 and D4 are provided to prevent the storage battery B2 from being charged with the power of the other storage batteries B1 and B3.

  Charging circuit 123 includes a converter circuit (not shown) that converts AC power into DC power, and charges corresponding storage battery B3. The output of the charging circuit 123 is also connected to the inverter 13 through the diode D5 so that DC power can be supplied to the inverter 13 even when the storage battery B3 is fully charged or charging is prohibited. The electric power charged in the storage battery B3 is supplied to the inverter 13 through the diode D6. The diodes D5 and D6 are provided to prevent the storage battery B3 from being charged with the power of the other storage batteries B1 and B2.

  The inverter 13 converts DC power into AC power and outputs it to the switch 14. The switch 14 selectively outputs AC power supplied from the commercial power source 2 or AC power supplied from the inverter 13 to the load device 3. The current detector 15 measures the current of the AC power output to the load device 3 and constantly monitors the current required by the load device 3. The control unit 16 is a known microcomputer control circuit, and is connected to all the components included in the power storage system 1 (not shown). The control unit 16 acquires connection destination information and controls their operations. The control unit 16 detects the occurrence of a power failure by constantly monitoring the power from the commercial power source 2. The internal power supply 17 converts AC power supplied from the commercial power supply 2 into DC power and supplies it to the control unit 16.

The control unit 16 performs control to switch the switch 14 so that AC power received from the commercial power supply 2 by the power storage system 1 is supplied to the load device 3 during normal times when no power failure occurs.
In addition, all subsequent descriptions are those in normal times.

  Storage batteries B1 to B3, charging circuits 121 to 123, inverter 13, control unit 16 and the like all consume power when energized. Therefore, the power storage system 1 supplies the current required by the load device 3 and the total current consumed by the power storage system 1 so that the current does not exceed the rated current of the commercial power supply 2 (for example, 15 A here). There is a need. Therefore, the upper limit of the current that the power storage system 1 can supply to the load device 3 is a current obtained by subtracting the internal current consumption of the power storage system 1 from the rated current.

  The upper limit of the current value assumed for the load device 3 is generally set based on the rated current. For this reason, when the internal current consumption increases as the capacity of the power storage system 1 increases, the current that can be supplied to the load device 3 may decrease unexpectedly. Therefore, the power storage system 1 according to the present invention reduces the internal current consumption of the power storage system 1 stepwise as the current required by the load device 3 increases in order to reduce the possibility that the current supplied to the load device 3 will be insufficient. Control to decrease. Specific control will be described below.

  FIG. 2 illustrates the relationship between the output current and the input current of the power storage system 1 according to the first embodiment of the present invention, and the change in the input current when the internal current consumption is controlled is indicated by a bold line. In FIG. 2, the horizontal axis represents the output current, and the vertical axis represents the input current. In the virtual power storage system 1 in which the internal current consumption is 0, the change in the input current is a straight line shown by a thin solid line.

The output current values Ia to Ig are current thresholds of the output current determined in advance as follows.
The output current value Ia is a current value (first current threshold value) set lower than the current value obtained by subtracting the total internal current consumption of the power storage system 1 from the rated current.
The output current value Ib is a current value obtained by adding the current value during charging of the storage battery B1 to the output current value Ia.
The output current value Ic is a current value obtained by adding the current value during charging of the storage battery B2 to the output current value Ib.
The output current value Id is a current value (second current threshold) obtained by adding the current value during charging of the storage battery B3 to the output current value Ic.
The output current value Ie is a current value obtained by adding the current value consumed by the charging circuit 121 to the output current value Id.
The output current value If is a current value obtained by adding the current value consumed by the charging circuit 122 to the output current value Ie.
The output current value Ig is a current value (third current threshold value) obtained by adding the current value consumed by the charging circuit 123 to the output current value If.

  When no current is consumed by the load device 3, the output current is zero. However, even in this case, from the commercial power source 2, a current having a current value Ih corresponding to the internal current consumption of the power storage system 1 is input to the power storage system 1.

  As the current required by the load device 3, that is, the output current increases, the input current also increases from the current value Ih. When the current value of the output current reaches the output current value Ia, the control unit 16 prohibits charging of the storage battery B1, thereby stopping the supply of current to the storage battery B1. At this time, the internal current consumption of the power storage system 1 decreases by the amount corresponding to the charging current of the storage battery B1. Therefore, the input current input from the commercial power supply 2 to the power storage system 1 decreases by the amount corresponding to the decrease in the internal current consumption, and the input current value decreases from the current value Ik to the current value Ii. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value Ia after this, the storage battery B1 that is in a charging prohibited state is allowed to be charged again.

  When the current value of the output current further increases and reaches the output current value Ib, the control unit 16 stops the current supply to the storage batteries B1 and B2 by prohibiting the charging of the storage battery B2 in addition to the storage battery B1. To do. At this time, the internal current consumption of the power storage system 1 decreases by the amount of the charging current of the two storage batteries B1 and B2. Therefore, the input current input from the commercial power source 2 to the power storage system 1 decreases by the amount corresponding to the decrease in the internal current consumption, and the input current value decreases from the current value Ik to the current value Ii. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value Ib after this, charging is permitted again for the storage battery B2 in the charge-prohibited state.

  When the current value of the output current further increases and reaches the output current value Ic, the control unit 16 prohibits charging of all the three storage batteries B1 to B3, thereby supplying current to all the storage batteries B1 to B3. To stop. At this time, the internal current consumption of the power storage system 1 decreases by the amount of the charging current of all the storage batteries B1 to B3. Therefore, the input current input from the commercial power source 2 to the power storage system 1 decreases by the amount corresponding to the decrease in the internal current consumption, and the input current value decreases from the current value Ik to the current value Ii. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value Ic after this, the storage battery B3 that is in the charge-prohibited state is allowed to be charged again.

  When the current value of the output current further increases and reaches the output current value Id, the control unit 16 cuts off the power supply to the charging circuit 121. At this time, the internal current consumption of the power storage system 1 decreases by the amount of the charging current of all the storage batteries B1 to B3 and the current consumption of the charging circuit 121. Therefore, the input current input from the commercial power supply 2 to the power storage system 1 decreases by the amount corresponding to the decrease in internal current consumption, and the input current value decreases from the current value Ik to the current value Ij. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value Id after this, power is supplied again to the charging circuit 121 whose power supply has been cut off.

  When the current value of the output current further increases and reaches the output current value Ie, the control unit 16 cuts off the power supply to the charging circuit 122 in addition to the charging circuit 121. At this time, the internal current consumption of the power storage system 1 decreases by the amount of the charging current of all the storage batteries B1 to B3 and the current consumption of the two charging circuits 121 and 122. Therefore, the input current input from the commercial power supply 2 to the power storage system 1 decreases by the amount corresponding to the decrease in internal current consumption, and the input current value decreases from the current value Ik to the current value Ij. As a result, a state where the current value of the input current reaches the rated current can be avoided. When the current value of the output current falls below the output current value Ie after this, power is supplied again to the charging circuit 122 that has been cut off from power supply.

  When the current value of the output current further increases and reaches the output current value If, the control unit 16 cuts off all power supply to the charging circuits 121 to 123. At this time, the internal current consumption of the power storage system 1 is reduced by the charging current of all the storage batteries B1 to B3 and the current consumption of all the charging circuits 121 to 123. Therefore, the input current input from the commercial power supply 2 to the power storage system 1 decreases by the amount corresponding to the decrease in internal current consumption, and the input current value decreases from the current value Ik to the current value Ij. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value If after this, power is supplied again to the charging circuit 123 that has been cut off from power supply.

  When the power supply to all the charging circuits 121 to 123 is interrupted, the inverter 13 cannot be operated because the power supply from the commercial power source is interrupted as it is, and can supply power without delay when a power failure occurs. Disappear. Therefore, the control unit 16 supplies DC power to the inverter 13 from the storage batteries B1 to B3 on condition that the current value of the output current reaches the output current value f and the power supply to all the charging circuits 121 to 123 is cut off. .

  When the current value of the output current continues to rise further and the value of the input current from the commercial power source 2 reaches the rated current, the value of the output current supplied to the load device 3 also reaches the upper limit. Since the value of the output current at this time is a current having a magnitude obtained by subtracting the minimum current necessary for maintaining the operation of the control unit 16 from the rated current, the maximum current can be supplied to the load device 3. become.

  As described above, the power storage system 1 according to the present invention can increase / decrease the internal current consumption of the power storage system 1 in accordance with the increase / decrease of the output current supplied to the load device 3, and the current required by the load device 3 As the current increases, the current that can be supplied to the load device 3 can be increased stepwise. Therefore, the possibility that the current supplied to the load device 3 is insufficient due to the internal current consumption can be reduced.

<Second embodiment>
Next, a second embodiment of the present invention will be described. The power storage system 1 of the present embodiment has the same components as the power storage system 1 of the first embodiment, and the control method is different. Hereinafter, the control method of the second embodiment and the change of the input current will be described.

  FIG. 3 is a relationship diagram between the output current and the input current of the power storage system 1 according to the second embodiment of the present invention, and the change in the input current when the internal current consumption is controlled is indicated by a bold line. In FIG. 3, the horizontal axis represents the output current, and the vertical axis represents the input current. In the virtual power storage system 1 in which the internal current consumption is 0, the change in the input current is a straight line shown by a thin solid line.

The output current values I1 to Io are output current thresholds determined in advance as follows.
The output current value Il is a current value (lower limit current threshold value) set lower than the current value obtained by subtracting the total internal current consumption of the power storage system 1 from the rated current.
The output current value Im is a current value obtained by adding the current value consumed by the storage battery B1 and the charging circuit 121 to the output current value Il.
The output current value In is a current value obtained by adding the current value consumed by the storage battery B2 and the charging circuit 122 to the output current value Im.
The output current value Io is a current value (upper limit current threshold value) obtained by adding the current value consumed by the storage battery B3 and the charging circuit 123 to the output current value In.

  When no current is consumed by the load device 3, the output current is zero. However, even in this case, a current having a current value Ip corresponding to the internal consumption current of the power storage system 1 is input from the commercial power supply 2 to the power storage system 1.

  As the current required by the load device 3, that is, the output current increases, the input current also increases from the current value Ip. When the current value of the output current reaches the output current value Il, the control unit 16 cuts off the power supply to the charging circuit 121. At this time, the internal current consumption of the power storage system 1 is reduced by the current consumption of the charging circuit 121 and the corresponding charging current of the storage battery B1. Therefore, the input current input from the commercial power source 2 to the power storage system 1 decreases by the amount corresponding to the decrease in internal current consumption, and the input current value decreases from the current value Ir to the current value Iq. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value Il thereafter, power is supplied again to the charging circuit 121 that has been cut off from power supply.

  When the current value of the output current further increases and reaches the output current value Im, the control unit 16 further cuts off the power supply to the charging circuit 122 in addition to the charging circuit 121. At this time, the internal current consumption of the power storage system 1 is reduced by the current consumption of the two charging circuits 121 and 122 and the charging current of the two storage batteries B1 and B2 corresponding to them. Therefore, the input current input from the commercial power source 2 to the power storage system 1 decreases by the amount corresponding to the decrease in internal current consumption, and the input current value decreases from the current value Ir to the current value Iq. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value Im thereafter, power is supplied again to the charging circuit 122 that has been cut off from power supply.

  When the current value of the output current further increases and reaches the output current value In, the control unit 16 cuts off all power supply to the three charging circuits 121 to 123. At this time, the internal current consumption of the power storage system 1 decreases by the amount of current consumed by all the charging circuits 121 to 123 and the charging current of all the storage batteries B1 to B3 corresponding thereto. Therefore, the input current input from the commercial power source 2 to the power storage system 1 decreases by the amount corresponding to the decrease in internal current consumption, and the input current value decreases from the current value Ir to the current value Iq. As a result, a state where the current value of the input current reaches the rated current can be avoided. If the current value of the output current falls below the output current value In thereafter, power is supplied again to the charging circuit 123 that has been cut off from power supply.

  When the power supply to all the charging circuits 121 is interrupted, the inverter 13 cannot be operated because the power supply from the commercial power supply is cut off as it is, and cannot supply power without delay when a power failure occurs. Therefore, the control unit 16 supplies DC power from the storage batteries B1 to B3 to the inverter 13 on condition that the current value of the output current reaches the output current value In and the power supply to all the charging circuits 121 to 123 is cut off. .

  When the current value of the output current continues to rise further and the value of the input current from the commercial power source 2 reaches the rated current, the value of the output current supplied to the load device 3 also reaches the upper limit. Since the value of the output current at this time is a current having a magnitude obtained by subtracting the minimum current necessary for maintaining the operation of the control unit 16 from the rated current, the maximum current can be supplied to the load device 3. become.

  As described above, the power storage system 1 can increase / decrease the internal current consumption of the power storage system 1 in accordance with the increase / decrease of the output current supplied to the load device 3, and the load increases as the current required by the load device 3 increases. The current that can be supplied to the device 3 can be increased stepwise. Therefore, the possibility that the current supplied to the load device 3 is insufficient due to the internal current consumption can be reduced.

<Modification>
Modifications of the first embodiment and the second embodiment described above will be described below. For example, when the output current value in the first embodiment reaches Ia, only the storage battery B1 is prohibited from being charged, and the storage batteries B2 and B3 are continuously charged. For this reason, a difference in the state of charge occurs between the storage batteries B1 to B3, and there is a risk that deterioration of only a specific storage battery is accelerated.

  Therefore, the control unit 16 performs control to selectively switch the storage batteries that are allowed to be charged to the plurality of storage batteries B1 to B3. Specifically, in the first embodiment, when the output current is from Ia to Ib, a combination of two storage batteries that allow charging (storage batteries B1 and B2, B2 and B3, or B1 and B3) is set at regular intervals. Switch sequentially. Further, in the first embodiment, when the output current is from Ib to Ic, one storage battery (storage battery B1, B2, or B3) that permits charging is sequentially switched at regular intervals. Thereby, the plurality of storage batteries B1 to B3 can be charged uniformly.

  Similarly, in the second embodiment, the control unit 16 selectively switches the charging circuits 121, 122, and 123 for the charging circuits that supply AC power from the commercial AC power supply sequentially. Specifically, in the second embodiment, when the output current is between Il and Im, a combination of two charging circuits (charging circuits 121 and 122, 122 and 123, or 121) that supplies AC power from a commercial AC power supply. 123) are sequentially switched at regular intervals. Further, in the second embodiment, when the output current is from Im to In, one charging circuit (charging circuit 121 and 122 or 123) for supplying AC power from the commercial AC power supply is sequentially switched at regular intervals. Thereby, the plurality of storage batteries B1 to B3 can be charged uniformly.

DESCRIPTION OF SYMBOLS 1 Power storage system 2 Commercial power supply 3 Load apparatus 11 Storage battery 12 Charging part 13 Inverter 14 Switch 15 Current detection part 16 Control unit 17 Internal power supply 18 Diode 121 Charging circuit

Claims (6)

A plurality of storage batteries;
A charging unit that converts AC power supplied from a commercial AC power source into DC power and charges the plurality of storage batteries;
A power converter that converts DC power supplied from the plurality of storage batteries into AC power;
A diode connected in parallel to the storage battery and capable of supplying DC power from the charging unit to the power converter;
An output unit that selectively outputs either AC power supplied from a commercial AC power source or AC power output by the power converter to a load device;
A current detection unit for detecting an output current of the output unit;
A control unit,
The control unit controls the output unit so that AC power output from the power converter is output to a load device while detecting a power failure of a commercial AC power source,
Depending on the magnitude of the output current of the output unit, provided that the output current of the output unit is not less than the first current threshold and less than the second current threshold while not detecting a power failure of the commercial AC power supply, The number of storage batteries that allow charging of the plurality of storage batteries is increased or decreased, and charging of all storage batteries of the plurality of storage batteries is prohibited on condition that the output current of the output unit is equal to or greater than the second current threshold. , Power storage system.
  2. The power storage system according to claim 1, wherein the control unit is configured such that an output current of the output unit is greater than or equal to a first current threshold and less than a second current threshold while no power failure is detected in a commercial AC power supply. As an electricity storage system, the storage batteries that permit charging of the plurality of storage batteries are selectively switched sequentially. The power storage system according to claim 1 or 2, wherein the charging unit includes a plurality of charging circuits corresponding to each storage battery of the plurality of storage batteries and operating with AC power supplied from a commercial AC power source,
While the control unit does not detect a power failure of the commercial AC power supply, the output current of the output unit is determined on the condition that the output current of the output unit is greater than or equal to the second current threshold and less than the third current threshold. Depending on the size, the number of charging circuits that supply AC power from the commercial AC power supply of the plurality of charging circuits is increased or decreased, and on condition that the output current of the output unit is equal to or greater than the third current threshold, A power storage system that interrupts all supply of AC power from a commercial AC power source to the plurality of charging circuits. A plurality of storage batteries;
A charging unit that converts AC power supplied from a commercial AC power source into DC power and charges the plurality of storage batteries;
A power converter that converts DC power supplied from the plurality of storage batteries into AC power;
A diode connected in parallel to the storage battery and capable of supplying DC power from the charging unit to the power converter;
An output unit that selectively outputs either AC power supplied from a commercial AC power source or AC power output by the power converter to a load device;
A current detection unit for detecting an output current of the output unit;
A control unit,
The charging unit corresponds to each storage battery of the plurality of storage batteries, and includes a plurality of charging circuits that operate with AC power supplied from a commercial AC power source,
The control unit controls the output unit so that AC power output from the power converter is output to a load device while detecting a power failure of a commercial AC power source,
Depending on the magnitude of the output current of the output unit, the plurality of the output currents of the output unit, on the condition that the output current of the output unit is greater than or equal to the lower limit current threshold and less than the upper limit current threshold while detecting a power failure of the commercial AC power supply The number of charging circuits that supply AC power from the commercial AC power supply of the charging circuit is adjusted to increase or decrease, and the plurality of charging circuits from the commercial AC power supply are provided on condition that the output current of the output unit is equal to or greater than the upper limit current threshold value. A power storage system that cuts off all AC power.
  5. The power storage system according to claim 4, wherein the control unit is configured such that the output current of the output unit is greater than or equal to a lower limit current threshold and less than an upper limit current threshold while a power failure of a commercial AC power supply is not detected. A power storage system that selectively and sequentially switches charging circuits that supply AC power from commercial AC power supplies of the plurality of charging circuits.   6. The power storage system according to claim 3, wherein commercial AC power is supplied to any of the plurality of charging circuits while the control unit does not detect a power failure of the commercial AC power. In the state, the power conversion device is operated with the DC power output from the charging circuit to which the commercial AC power is supplied, and the supply of AC power from the commercial AC power source to the plurality of charging circuits is interrupted. A power storage system in which the power conversion device operates with DC power supplied from the plurality of storage batteries.

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