JP5556258B2 - Uninterruptible power system - Google Patents

Description

    The present invention relates to an uninterruptible power supply apparatus that connects a plurality of converter units and inverter units in parallel and controls the number of converter units and inverter units that are operated according to load power or load current. The present invention relates to a technique for suppressing charge / discharge.

  A general uninterruptible power supply (UPS) includes a converter unit that converts alternating current into direct current, a storage battery that stores electric power converted into direct current, and an inverter unit that converts direct current into alternating current. As shown in Patent Document 1, the converter unit and the inverter unit are divided into a plurality of units in order to extend the life of the device and increase the efficiency (reduction of generated loss), and load power or load during operation. A method of controlling the number of operating units suitable for the current is known.

  FIG. 8 shows a conventional example of an uninterruptible power supply apparatus in which a plurality of converter units and inverter units are connected in parallel, and the number of operating units is controlled in accordance with load power or load current. In FIG. 8, 1 is an AC power supply, 2 is a converter device composed of n converter units 2-1 to 2-n (n is an integer), and 6 is an output of the converter device 2 and an input of the inverter device 7. A storage battery connected to the connected DC bus, 7 is an inverter device composed of n inverter units 7-1 to 7-n, 8 is a load, and 9 is a current detector for detecting a load current. Reference numeral 10 denotes an inverter operation number control circuit for controlling the number of operating inverter units, and reference numeral 11 denotes a converter operation number control circuit for controlling the operation number of converter units.

  In such a configuration, the converter device 2 supplies DC power to the inverter device 7 while charging the storage battery 6. Further, the load current during operation of the device is detected by the current detector 9, and from the detection result, the converter operation number control circuit 11 and the inverter operation number control circuit 10 calculate the necessary number of operations, and this is currently operated. Always control the number of units required for the load. By performing such control, for example, when the load is light, the converter unit or the inverter unit can be efficiently operated by reducing the excessive number of operating units. Can be realized.

JP 2008-228517 A

  FIG. 9 shows an example of a conventional circuit when two converter units (maximum output current = I1: see FIG. 10) are connected in parallel. FIG. 10 shows the operation waveforms of the respective parts at the time of sudden load change in the circuit example of FIG. In FIG. 9, when the initial required load (the load current measured by the current detector 9) is I1, the operation number control circuit 11 turns on the operation signal of the converter unit 2-1, and the operation of the converter unit 2-2. The signal is turned off, and the load current I1 is borne only by the converter unit 2-1. At this time, as shown in FIG. 10, when the required load becomes I2 (here, a current twice as large as I1) due to a sudden load change, the converter unit 2-1 alone cannot bear the load current. The number-of-operations control circuit 11 also turns on the operation signal of the converter unit 2-2 and shares the load current I2 between the converter unit 2-1 and the converter unit 2-2. As described above, even when the load suddenly changes, the number of operating units is switched according to the magnitude of the load current.

  However, since the operation signal of the converter unit 2-2 is turned on and before the converter unit 2-2 actually operates, at least a delay time Δt occurs due to the influence of control delay and the like. As a result, the power supply to the load during the operation delay time Δt is covered by the discharge from the storage battery as shown in FIG. Charging / discharging operation will occur.

  As described above, in an uninterruptible power supply that controls the number of converter units or inverter units that are operated, the storage battery repeats the charge / discharge operation every time the operation number is switched due to a sudden load change or the like. It becomes a factor to accelerate deterioration. As a result, the device life may be shortened.

In addition, when the DC voltage fluctuates due to a delay in the control response of the converter at the time of sudden load change, the storage battery is similarly charged and discharged, which similarly causes acceleration of deterioration of the storage battery.
The present invention has been made in view of the above problems, and controls the number of converter units or inverter units to be operated by suppressing deterioration of storage batteries due to factors such as switching operation of the number of operating units or delay in control response during sudden load changes. An object of the present invention is to provide an uninterruptible power supply that can be used.

  In order to solve the above-described problems, in the first invention, a converter device in which a plurality of converter units that convert alternating current into direct current are connected in parallel, a storage battery that can be charged and discharged, and an inverter that converts direct current into alternating current An inverter device in which a plurality of units are connected in parallel, and an AC power source is connected to the input of the converter device, the storage battery and the inverter device are connected to the output of the converter device, and a load is connected to the output of the inverter device. In an uninterruptible power supply that controls the number of operating converter units or inverter units according to load power or load current, energy charging / discharging of the storage battery during switching operation of the number of operating converter units or inverter units Charge / discharge suppression means for suppressing the operation, and its energy instead of the storage battery. Energy compensation means for compensating for energy.

In a second invention, the charge / discharge suppression means in the first invention is a switch circuit that disconnects the storage battery from the uninterruptible power supply.
In a third invention, the charge / discharge suppression means in the first invention connects, in parallel with the storage battery, energy compensation means comprising a capacitor and a capacitor charge / discharge control circuit for controlling the charge / discharge operation of the capacitor. The output voltage of the energy compensation means is set higher than the storage battery voltage.

  In 4th invention, the said energy compensation means in 1st-3rd invention comprises a capacitor and the capacitor charging / discharging control circuit which controls the charging / discharging operation | movement of a capacitor, The said storage battery or a storage battery, and the said charging / discharging suppression It is characterized by being connected in parallel with a series circuit with the means.

  In a fifth aspect of the invention, a converter device in which a plurality of converter units for converting alternating current to direct current are connected in parallel, a storage battery capable of charge / discharge, and an inverter in which a plurality of inverter units for converting direct current to alternating current are connected in parallel An AC power source at the input of the converter device, the storage battery and the inverter device at the output of the converter device, and a load at the output of the inverter device, respectively, and depending on load power or load current The uninterruptible power supply for controlling the number of operating units of the converter unit or the inverter unit includes a discharge suppressing means for suppressing an energy discharging operation of the storage battery during the switching operation of the number of operating units of the converter unit or the inverter unit.

  In a sixth aspect of the invention, the discharge suppression means in the fifth aspect of the invention is configured by connecting, in parallel with the storage battery, energy compensation means composed of a capacitor and a capacitor charge / discharge control circuit that controls the charge / discharge operation of the capacitor. The output voltage of the energy compensating means is made higher than the storage battery voltage.

In the seventh invention, the storage battery in the fifth or sixth invention is charged from an AC input power source through an AC-DC conversion type charger.
In the eighth invention, the storage battery in the fifth or sixth invention is charged from the output of the converter device via a DC-DC conversion type charger.

  In a ninth invention, the capacitor charge / discharge control circuit in the first to eighth inventions is a DC-DC converter circuit capable of bidirectionally converting an arbitrary DC voltage into another arbitrary DC voltage. .

In a tenth invention, the capacitor in the first to ninth inventions is a lithium ion capacitor.
In an eleventh invention, the capacitor in the first to ninth inventions is an electric double layer capacitor.

  According to the present invention, a capacitor circuit composed of a capacitor and a charge / discharge control circuit thereof is connected in parallel with the storage battery, and charging / discharging of energy from the storage battery during switching operation of the converter unit or the inverter unit is performed. Only by suppressing and charging / discharging energy from the capacitor, deterioration due to charging / discharging of the storage battery other than the operation at the time of power failure can be prevented. As a result, it is possible to extend the life of the device.

1 is a circuit diagram showing a first embodiment of the present invention. It is a circuit diagram for demonstrating operation | movement of the 1st Example of this invention. It is operation | movement explanatory drawing (at the time of load increase) of FIG. It is operation | movement explanatory drawing (at the time of load reduction) of FIG. It is a circuit diagram which shows the 2nd Example of this invention. It is a circuit diagram which shows the 3rd Example of this invention. It is a circuit diagram which shows the 4th Example of this invention. It is a circuit diagram which shows the conventional Example. It is a circuit diagram for demonstrating operation | movement of the conventional Example. It is operation | movement explanatory drawing of FIG.

  The gist of the present invention is that in an uninterruptible power supply device including a converter device in which a plurality of converter units are connected in parallel, a storage battery, and an inverter device in which a plurality of inverter units are connected in parallel, according to load power or load current. When controlling the number of operating units of the converter unit or the inverter unit, the energy charging / discharging operation of the storage battery during the switching operation of the operating number of the converter unit or the inverter unit is suppressed, and the energy instead of the storage battery is controlled. It is a point provided with the energy compensation means which compensates.

FIG. 1 shows a first embodiment of the present invention. Components having the same functions as those of the conventional example of FIG.
In FIG. 1, 1 is an AC power supply, 2 is a converter device composed of n converter units (2-1 to 2-n) (n is an integer), and 5 is composed of a capacitor charge / discharge control circuit 3 and a capacitor 4. Capacitor circuit, 6 is a storage battery, 7 is an inverter device composed of n (n is an integer) inverter units (7-1 to 7-n), 8 is a load, 9 is a current detector, and 10 is an inverter An inverter operation number control circuit for controlling the number of units operated, 11 is a converter operation number control circuit for controlling the number of converter units, and 12 is a switch circuit.

  In FIG. 1, a storage battery 6 and a switch circuit 12 are connected in series with respect to the conventional example of FIG. 8, and a capacitor circuit 5 including a capacitor charge / discharge control circuit 3 and a capacitor 4 is connected in parallel at both ends thereof. . The control signal line is connected to the capacitor charge / discharge control circuit 3 and the switch circuit 12 from the inverter operation number control circuit 10 and the converter operation number control circuit 11.

  Next, the operation of the present invention will be described with reference to FIGS. FIG. 2 shows a converter unit (maximum output current = I1: see FIGS. 3 and 4) connected in parallel (2-1 and 2-2), and is one of DC-DC converter circuits as a capacitor charge / discharge circuit. It is an example at the time of applying a buck-boost chopper circuit. In FIG. 2, a switch circuit 12 is a circuit (for example, a switch circuit using a semiconductor) that can switch on and off at high speed. 3 is an operation waveform of each part at the time of sudden load change (load increase) in the circuit example of FIG. 2, and FIG. 4 is an operation waveform of each part at the time of load decrease.

In FIG. 3, when the initial required load (load current measured by the current detector 9) is I1, the operation number control circuit 11 of the converter device 2 turns on the operation signal of the converter unit 2-1, and the converter unit 2 -2 is turned off, and the load current I1 is borne only by the converter unit 2-1. Next, when the required load becomes I2 (here, a current twice as large as I1) due to a sudden load change (load increase), the converter unit 2-1 alone cannot bear the load current. The operation number control circuit 11 turns on the operation signal of the converter unit 2 as well.
At the same time, the operating number control circuit 11 outputs a switch “OFF” command to the switch circuit 12 and a “discharge start” command to the capacitor charge / discharge control circuit 3. As a result, the discharge of energy from the storage battery 6 is suppressed by the switch circuit 12, and instead the energy from the capacitor 4 via the capacitor charge / discharge circuit (IGBTTT 1, T 2, a step-up / step-down chopper circuit composed of a DC reactor DCL) 5. Is started to discharge. Capacitors focus on the extremely long charge / discharge cycle life compared to storage batteries (for example, lead batteries). Power outage operation is performed by causing the capacitors to supply power to the load during the operation delay time Δt. Deterioration due to charge / discharge of the storage battery at times other than the time can be prevented.
Further, after the switching operation is completed (after Δt time), the operating number control circuit 11 outputs a switch “ON” command to the switch circuit 12 and a “discharge stop” command to the capacitor charge / discharge control circuit 3, respectively. The unit 2-1 and the converter unit 2-2 are in a normal operation for sharing the load current I2. In addition, by charging the energy discharged during the normal operation through the capacitor charging / discharging circuit 3, it is possible to cope with the next sudden load change.

FIG. 4 shows an operation example when the load is suddenly reduced. When the load decreases rapidly, the load current of the converter device 2 decreases rapidly, so that the direct current voltage rises due to a delay in control response, and the storage battery is charged. In order to avoid this, when the load current is reduced by half while the load current I2 (= I1 × 2) is borne by the converters 2-1 and 2-2, respectively, the control of the number of operating the converter device 2 is performed. The circuit 11 issues an operation stop command to the converter unit 2-2. At the same time, the operating number control circuit 11 outputs a switch “OFF” command to the switch circuit 12 and a “charge start” command to the capacitor charge / discharge control circuit 3.
As a result, charging of the energy to the storage battery 6 is suppressed by the switch circuit 12, and instead, the capacitor 4 absorbs energy via the capacitor charging / discharging circuit (step-up / step-down chopper circuit). Thereafter, with the control response converged and the converter unit 2-2 disconnected, the energy absorbed by the capacitor is released to the inverter input, and the switch circuit 12 is used as a switch “ON” command to Is possible. It becomes possible to suppress the charging / discharging operation of the storage battery when the number of operating units is switched according to the load power or the load current, and the life of the storage battery can be extended.

  In the inverter device, when switching the number of operating inverter units according to load power or load current, the charge / discharge operation of the storage battery can be suppressed by the same operation.

FIG. 5 shows a second embodiment of the present invention. The difference from the first embodiment is that the switch circuit 12 connected in series with the storage battery in the first embodiment is omitted. In the case of the present embodiment, this can be realized by setting the output voltage of the capacitor circuit 5 constituted by the capacitor charge / discharge circuit 3 and the capacitor 4 to be higher than the voltage of the storage battery 6 and providing a current limiting function.
For example, in the operation in the example of FIG. 3 in which the number of converter units operated is increased as shown in the first embodiment, the capacitor circuit 5 has a smaller output impedance than the storage battery 6 during the response delay time Δt at the time of switching. In order to operate as a power source, DC power is supplied from the capacitor 4 to the inverter device 7 through the capacitor charge / discharge control circuit 3 according to a command from the operating number control circuit 11. As a result, as in the first embodiment, it is possible to suppress the charging / discharging operation of the storage battery when the number of operating units is switched according to the load power or the load current, and the life of the storage battery can be extended.

FIG. 6 shows a third embodiment of the present invention. The difference from the first embodiment is that a diode 13 is connected in series with the storage battery 6 instead of the switch circuit 12, and an AC-DC conversion type charger 14 is connected between the AC power supply 1 and the storage battery 6. Is a point. Steadyly, the operation number control of the converter device 2 and the inverter device 7 is the same as that of the first embodiment. In this embodiment, the voltage of the DC bus connecting the output of the converter device 2 and the input of the inverter device 7 is controlled by the converter device 2 to be higher than the voltage of the storage battery 6. In the operation in the example of FIG. 3 in which the number of converter units operated in the first embodiment is increased, the capacitor circuit 5 receives the command from the operation number control circuit 11 during the response delay time Δt at the time of switching. DC power is supplied to the inverter device 7 through the capacitor charge / discharge control circuit 3. At this time, since the voltage of the DC bus is higher than the voltage of the storage battery 6, the storage battery 6 is not discharged.
Further, in the operation in the example of FIG. 4 in which the number of converter units operated is reduced, the voltage of the DC bus is controlled to be higher than the fluctuation of the voltage of the storage battery 6, so that the fluctuation of the DC bus voltage due to the delay in the control response Even if it exists, the discharge from the storage battery 6 does not occur. As a result, as in the first embodiment, it is possible to suppress the charging / discharging operation of the storage battery when the number of operating units is switched according to the load power or the load current, and the life of the storage battery can be extended.

  FIG. 7 shows a fourth embodiment of the present invention. The difference from the third embodiment is that a DC-DC conversion type charger 15 is connected in parallel with the diode 13 as a charger for charging the storage battery. Since the voltage of the storage battery 6 is lower than the voltage of the DC bus, it is charged with a step-down DC-DC conversion type charger. Other operations and effects are the same as in the third embodiment.

  Although the present invention is an example of an uninterruptible power supply device, it can be applied to an electric motor drive device in which a converter or an inverter is composed of a plurality of units and a storage battery is connected to a DC circuit, a DC power supply device, or the like.

DESCRIPTION OF SYMBOLS 1 ... AC power source 2 ... Converter apparatus
3 ... Capacitor charge / discharge control circuit 4 ... Capacitor
DESCRIPTION OF SYMBOLS 5 ... Capacitor circuit 6 ... Storage battery 7 ... Inverter apparatus 8 ... Load 9 ... Current detector
10 ... Inverter operation number control circuit
DESCRIPTION OF SYMBOLS 11 ... Converter operation number control circuit 12 ... Switch circuit 13 ... Diode 14 ... AC-DC conversion type charger 15 ... DC-DC conversion type charger

Claims (11)

A converter device comprising a plurality of converter units connected in parallel for converting alternating current to direct current; a storage battery capable of charge / discharge; and an inverter device comprising a plurality of inverter units connected in parallel for converting direct current to alternating current. An AC power source is connected to the input of the device, the storage battery and the inverter device are connected to the output of the converter device, and a load is connected to the output of the inverter device, respectively, and the converter unit or the inverter depending on load power or load current In an uninterruptible power supply that controls the number of operating units,
Charge / discharge suppression means for suppressing charging or discharging operation of energy of the storage battery during switching operation of the number of operating units of the converter unit or the inverter unit, and energy compensation means for compensating the energy instead of the storage battery. An uninterruptible power supply.   The uninterruptible power supply according to claim 1, wherein the charge / discharge suppression means is a switch circuit that disconnects the storage battery from the uninterruptible power supply.   The charge / discharge suppression means connects an energy compensation means composed of a capacitor and a capacitor charge / discharge control circuit for controlling the charge / discharge operation of the capacitor in parallel with the storage battery, and outputs the output voltage of the energy compensation means to the storage battery. The uninterruptible power supply according to claim 1, wherein the uninterruptible power supply is set higher than the voltage.   The energy compensation means comprises a capacitor and a capacitor charge / discharge control circuit that controls the charge / discharge operation of the capacitor, and is connected in parallel with the storage battery or a series circuit of the storage battery and the charge / discharge suppression means. The uninterruptible power supply according to any one of claims 1 to 3. A converter device comprising a plurality of converter units connected in parallel for converting alternating current to direct current; a storage battery capable of charge / discharge; and an inverter device comprising a plurality of inverter units connected in parallel for converting direct current to alternating current. An AC power source is connected to the input of the device, the storage battery and the inverter device are connected to the output of the converter device, and a load is connected to the output of the inverter device, respectively, and the converter unit or the inverter depending on load power or load current In an uninterruptible power supply that controls the number of operating units,
An uninterruptible power supply comprising a discharge suppressing means for suppressing a discharge operation of energy of the storage battery during a switching operation of the number of operating units of the converter unit or the inverter unit.   The discharge suppression means is connected in parallel with a storage battery / diode series connection circuit in which a diode is connected in series with the storage battery, and an energy compensation means comprising a capacitor and a capacitor charge / discharge control circuit for controlling the charge / discharge operation of the capacitor. The uninterruptible power supply according to claim 5, wherein an output voltage of the energy compensating means is made higher than a voltage of the storage battery.   The uninterruptible power supply according to claim 5 or 6, wherein the storage battery is charged from an AC input power source through an AC-DC conversion type charger.   The uninterruptible power supply according to any one of claims 5 to 7, wherein the storage battery is charged from an output of the converter device via a DC-DC conversion type charger. The capacitor discharge control circuit, the DC capable of converting bidirectionally any DC voltage to any other DC voltage - claim 3, 4, which is a direct-current converter circuit, either 6 The uninterruptible power supply according to item 1. The uninterruptible power supply according to any one of claims 3, 4, and 6 , wherein the capacitor is a lithium ion capacitor. The uninterruptible power supply according to any one of claims 3, 4, and 6 , wherein the capacitor is an electric double layer capacitor.

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