JP5561071B2 - Uninterruptible power system - Google Patents

Description

  The present invention relates to an uninterruptible power supply, and more particularly to an uninterruptible power supply having a function of backing up for a long time and a function of absorbing regenerative power from a load.

  An uninterruptible power supply (UPS) uses a stable power supply as a load by switching to a backup power supply without interruption in the event of an AC power supply voltage drop, power failure, instantaneous voltage drop, or instantaneous power failure (hereinafter referred to as a power failure). To supply. A storage battery (mainly a lead storage battery) is used as the storage medium serving as the backup power source. There is also an uninterruptible power supply using an electric double layer capacitor as a power storage medium. Furthermore, there is an uninterruptible power supply using a storage battery and an electric double layer capacitor (for example, see Patent Documents 1 and 2).

  FIG. 7 is a diagram illustrating a configuration of a conventional uninterruptible power supply of a conventional commercial power supply method. An uninterruptible power supply apparatus 100 shown in FIG. 7 includes a UPS unit 104 including a power converter 101, a voltage detection circuit 102, and an AC switch 103, and a power storage unit 105 formed of a storage battery or an electric double layer capacitor.

  The AC switch 103 is provided between the AC input terminal ACIN and the AC output terminal ACOUT. The AC switch 103 is in an ON state in a normal time when the commercial AC power supply 106 connected to the AC input terminal ACIN is normal, and the commercial AC power supply 106 is powered off based on a detection signal from the voltage detection circuit 102. In the case of abnormalities such as, it is turned off.

  Power converter 101 has a function of supplying power bidirectionally between power storage unit 105 and AC output terminal ACOUT, and charges and discharges power storage unit 105.

  FIG. 8 is a diagram for explaining the operation of the uninterruptible power supply 100. FIG. 8A is a diagram illustrating an operation when the commercial power supply 106 is normal, and FIG. 8B is a diagram illustrating an operation when the commercial power supply 106 is abnormal. As shown in FIG. 8A, when the AC power supply 106 connected to the AC input terminal ACIN of the uninterruptible power supply 100 is normal, the AC switch 103 shown in FIG. Via this, AC power is sent from the AC power source 106 to the load 109. At this time, the power converter 101 illustrated in FIG. 7 operates as a rectifier that charges the power storage unit 105.

  As shown in FIG. 8B, when the AC power supply 106 connected to the AC input terminal ACIN of the uninterruptible power supply 100 becomes abnormal due to a power failure (indicated by symbol S in the figure), it is shown in FIG. The AC switch 103 is turned off, and the power converter 101 operates as an inverter that converts the DC power of the power storage unit 105 into AC power and supplies the AC power to the load 109. Then, power is sent in the directions indicated by arrows 110 and 111.

  Here, when the load 109 is an inductive load such as an induction motor, the load 109 has a power running that consumes power and a regeneration that generates regenerative power. When the AC power supply 106 is normal and regenerative power is generated by a load 109 such as an induction motor, the regenerative power is sent in the directions indicated by arrows 112 and 113 as shown in FIG. There is no problem because the commercial AC power supply 106 absorbs this regenerative power. On the other hand, as shown in FIG. 8B, when the AC power supply 106 is abnormal and the power converter 101 shown in FIG. Regenerative power is sent in the direction shown, and the power storage unit 105 made of a storage battery or an electric double layer capacitor is charged. However, in the power storage unit 105, if an electric double layer capacitor is used instead of the storage battery, rapid discharge and quick charge can be performed. Therefore, it is only necessary to charge in advance by reducing the voltage by the amount of regenerative power absorption.

  Further, in the uninterruptible power supply using the storage battery and the electric double layer capacitor disclosed in Patent Document 1, when a power failure or the like is detected, the first power conversion in which the electric double layer capacitor is connected by a discharge command The battery discharges the electric power of the electric double layer capacitor, not the storage battery. And a 1st power converter stops discharge, when the electric power or voltage of an electric double layer capacitor becomes below a regulation level. Further, when the first power converter is stopped, this time, the second power converter to which the storage battery is connected is discharged from the storage battery. Furthermore, when a power failure or the like is canceled, both the storage battery and the electric double layer capacitor are charged using the second power converter and the first power converter, respectively, according to the charging command.

JP 2010-16996 A JP 2009-20208 A

  However, when a storage battery is used for the power storage unit in a conventional uninterruptible power supply, the storage battery can be rapidly discharged, but cannot be rapidly charged.Therefore, when a large amount of regenerative power is generated in the load, the voltage of the storage battery increases rapidly. There is a problem that the protection function may cause a stop due to a DC overvoltage. In addition, when an electric double layer capacitor is used for the power storage unit, the electric double layer capacitor has a smaller capacity than the storage battery, so that in the event of a power failure, the compensation time is shortened. There is a problem that increasing the capacitance of the electric double layer capacitor to increase the compensation time leads to an increase in cost.

  Further, in the case of an uninterruptible power supply using a conventional storage battery and an electric double layer capacitor, when a power failure is detected, the first power converter is not a storage battery but an electric double layer capacitor when a discharge command is detected. In order to discharge the electric power, it is necessary to back up the electric double layer capacitor for a predetermined time, and it is necessary to absorb the regenerative power. The capacity required for the electric double layer capacitor at that time can be calculated, for example, as follows.

  For example, let's consider giving an electric double layer capacitor the ability to discharge 80 kW of power for 5 seconds and the ability to absorb 40 kW of regenerative power from the load for 2 seconds. At this time, the working voltage range of the electric double layer capacitor is 400V to 300V.

  In this case, the discharge energy is calculated as 80 kW × 5 sec = 400 kJ, and the absorbed energy is calculated as 40 kW × 2 sec = 80 kJ.

  Before the electric double layer capacitor absorbs 40 kW of regenerative power for 2 seconds, 80 kW of power is discharged for 5 seconds, and before the electric double layer capacitor discharges 80 kW of power for 5 seconds, absorbs 40 kW of regenerative power for 2 seconds. Therefore, the energy E that can be stored in the electric double layer capacitor within the working voltage range of 400V to 300V needs to be E = 400 kJ + 80 kJ = 480 kJ. At this time, if the required capacitance of the electric double layer capacitor is C, 480k = 0.5C (400 ^ 2-300 ^ 2) is established, and when the capacity C is solved, C = 480k × 2 ÷ (400 ^ 2− 300 ^ 2) = 13.7F. Such an electric double layer capacitor having a working voltage range of 400V to 300V and a capacity of 13.7F is currently about 5 million yen and is expensive.

  As described above, the conventional uninterruptible power supply has a problem that it is expensive to back up for a long time and absorb regenerative power.

  In view of the above problems, an object of the present invention is to provide an uninterruptible power supply device having a function of backing up at low cost for a long time and a function of absorbing regenerative power from a load.

The uninterruptible power supply according to the present invention is configured as follows in order to achieve the above object.
A first uninterruptible power supply (corresponding to claim 1) includes an AC input terminal for connecting an AC power supply, an AC output terminal for connecting a load, and an AC input terminal and an AC output terminal. A first power converter having a connected AC switch, an AC terminal and a DC terminal, the AC terminal being connected to the AC switch on the AC output terminal side, and connected to the DC terminal of the first power converter And the abnormality detecting means for detecting whether or not the AC voltage input from the AC input terminal is abnormal. When the abnormality detecting means detects the abnormality, the AC switch is turned off, and the first power converter A first control means for controlling the regenerative power connected to the first energy storage and storage element in parallel via the first energy storage and storage element and the second power converter. Second energy storage to absorb water A storage element; current detection means for detecting a current flowing through the power storage means; and second control means for controlling the second power converter based on a detected current from the current detection means. To do.
The second uninterruptible power supply (corresponding to claim 2) is an AC input terminal for connecting an AC power supply, an AC output terminal for connecting a load, and an AC power input from the AC input terminal as a direct current. An AC / DC converter that converts electric power to output to a DC link unit; a DC / AC converter that converts DC power input from the DC link unit into another AC power and outputs the AC power to an AC output terminal; A first power converter having a direct current terminal and a second direct current terminal, wherein the first direct current terminal is connected to the direct current link unit; and a second direct current terminal of the first power converter. The power storage means, an abnormality detection means for detecting whether or not the AC voltage input from the AC input terminal is abnormal, and when the abnormality detection means detects an abnormality, the AC / DC converter is turned off, and the first power converter First control means for controlling The power storage means includes a first energy storage and storage element and a second energy storage and storage element for absorbing regenerative power connected in parallel with the first energy storage and storage device via the second power converter. And a current detection means for detecting a current flowing through the power storage means, and a second control means for controlling the second power converter based on the detected current from the current detection means.
In the third uninterruptible power supply (corresponding to claim 3), preferably, in the above configuration, the second control means is such that the abnormality detection means detects an abnormality and the detected current from the current detection means is loaded. The second power converter is controlled so as to charge the second energy storage and storage element when charging from the battery to the power storage means is indicated.
The fourth uninterruptible power supply (corresponding to claim 4) is preferably configured as described above, wherein the second control means is configured such that when the detected current from the current detecting means indicates discharge from the power storage means to the load. The second power converter is controlled so that the charging voltage of the second energy storage and storage element is discharged until a predetermined value is reached.
In the fifth uninterruptible power supply (corresponding to claim 5), in the above configuration, preferably, the power storage means flows through the first current detector as the current detection means and the second energy storage element. A second current detector for detecting current; the second control means detects the abnormality by the abnormality detection means, and the detected current from the first current detector charges the power storage means from the load. When charging, the second energy storage element is charged so that the difference between the detected current from the first current detector and the detected current from the second current detector is zero. The power converter is controlled.
In the sixth uninterruptible power supply (corresponding to claim 6), the second control means preferably has the detection current from the first current detector as the current detection means from the power storage means. When the discharge to the load is indicated, the second power converter is controlled so as to discharge the charging voltage of the second energy storage and storage element until a predetermined value is reached.
The seventh uninterruptible power supply (corresponding to claim 7) is preferably characterized in that, in the above configuration, the first energy storage and storage element is a storage battery.
The eighth uninterruptible power supply (corresponding to claim 8) is characterized in that, in the above configuration, the second energy storage element is an electric double layer capacitor.
The ninth uninterruptible power supply (corresponding to claim 9) is preferably characterized in that, in the above configuration, the second energy storage and storage element is a flywheel power storage device.

  ADVANTAGE OF THE INVENTION According to this invention, the uninterruptible power supply device which has the function to back up cheaply for a long time, and the function which can absorb the regenerated electric power from load can be provided.

It is a block diagram which shows the structure of the uninterruptible power supply which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the electrical storage part of the uninterruptible power supply which concerns on the 1st Embodiment of this invention. It is a flowchart explaining operation | movement of the uninterruptible power supply which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the uninterruptible power supply which concerns on the 2nd Embodiment of this invention. It is a flowchart explaining operation | movement of the uninterruptible power supply which concerns on the 2nd Embodiment of this invention. It is a figure which shows a flywheel-type electric power storage apparatus. It is a figure which shows the structure of the conventional uninterruptible power supply system of the usual commercial electric power feeding system. It is a figure explaining operation | movement of the conventional uninterruptible power supply apparatus, (a) is a figure which shows operation | movement when the alternating current power supply of a commercial system is normal, (b) is an abnormality in the alternating current power supply of a commercial system. It is a figure which shows operation | movement at the time.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing the configuration of the uninterruptible power supply according to the first embodiment of the present invention. The uninterruptible power supply 10 is a constant commercial power supply system that supplies the AC power of the AC power supply 11 to the load 13 when the AC power supply 11 is normal. The uninterruptible power supply 10 is connected between an AC input terminal 12 for connecting an AC power supply 11, an AC output terminal 14 for connecting a load 13, and the AC input terminal 12 and the AC output terminal 14. A first power converter 18 having an AC switch 15, an AC terminal 16 and a DC terminal 17, the AC terminal 16 being connected to the AC switch 15 on the AC output terminal 14 side, and a first power converter 18. A power storage unit 19 as a power storage unit connected to the DC terminal 17, an abnormality detection unit 20 as an abnormality detection unit for detecting whether or not the AC voltage of the AC power supply 11 input from the AC input terminal 12 is abnormal, When the abnormality detection unit 20 detects an abnormality, the first switch 21 is provided as a first control unit that turns off the AC switch 15 and controls the first power converter 18.

  When the abnormality detection unit 20 detects an abnormality such as a power failure of the AC power supply 11, the first control unit 21 sends a detection signal to the AC switch 15 and the first power converter 18.

  The AC switch 15 is a bidirectional switch composed of a thyristor or the like. The AC switch 15 is connected between the AC input terminal 12 and the AC output terminal 14, and is normally turned on when the AC power supply 11 is normal. In the case of an abnormal condition such as that, an OFF state is entered based on the detection signal from the first control unit 21.

  The first power converter 18 has a function for supplying power bidirectionally between the power storage unit 19 and the AC output terminal 14 (load 13). When the AC power supply 11 has a power failure or the like, based on the control signal from the first control unit 21, the first power conversion unit 18 switches so as to discharge from the power storage unit 19 to the AC output terminal 14, and switches to the power storage unit 19. The accumulated DC power is converted into AC power and supplied to the AC output terminal 14. The first power converter 18 operates as an inverter.

  When the AC power supply 11 is restored or when the voltage drop is restored, the first power converter 18 transfers the discharge from the power storage unit 19 to the power storage unit 19 based on the control signal from the first control unit 21. Switch to charging. The first power converter 18 operates as a rectifier that charges the power storage unit 19.

  The power storage unit 19 includes a storage battery 22 as a first energy storage and storage element, and a second energy storage and storage element for absorbing regenerative power connected in parallel with the storage battery 22 via a second power converter 23. As an electric double layer capacitor 24, a first current detector 25 as current detecting means for detecting a current flowing through the power storage unit 19, and a second current detector 26 detecting a current flowing through the electric double layer capacitor 24. And a second control unit 27 that controls the second power converter 23 based on the current detected by the first current detector 25 and the second current detector 26.

  The storage battery 22 may be a storage battery such as lithium ion or nickel metal hydride in addition to the lead storage battery.

  The second power converter 23 has a function of supplying power bidirectionally between the electric double layer capacitor 24 and the load 13 via the first power converter 18. The second power converter 23 is controlled by the second control unit 27 as described in detail later.

  In the above configuration, an electric double layer capacitor 24 for absorbing regenerative power is connected to the DC terminal 17 of the first power converter 18 in parallel with the storage battery 22 via the second power converter 23. When regenerative power is generated from the load 13 while the first power converter 18 is operating as an inverter, the voltage of the storage battery 22 rises. Therefore, the second power converter 23 has an electric double layer capacitor so as to suppress the voltage rise. 24 causes regenerative power to be absorbed.

The second control unit 27 calculates the current flowing into and out of the storage battery 22 from the difference between the current detected by the first current detector 25 and the current detected by the second current detector 26. Then, the second power converter 23 is operated to output the calculated current using the electric power of the electric double layer capacitor 24. That is, the control operation by the second control unit 27 is as follows.
(1) When an abnormality such as a power failure is detected and a backup operation state is established, the current flowing through the storage battery 22 is detected by the first and second current detectors 25 and 26.
(2) When the current detected by the first current detector 25 is in the charging direction, the second power converter 23 is an electric double layer capacitor that can be rapidly charged so that the charging current to the storage battery 22 becomes zero. Current is passed to 24.
(3) When the current detected by the first current detector 25 is in the discharging direction and the electric double layer capacitor 24 that can be rapidly charged is charged more than the specified amount, the second power converter 23 Discharges the electric double layer capacitor 24 to a specified amount.
(4) When the power failure is recovered and normal operation is started, the second power converter 23 discharges the electric double layer capacitor 24 to a specified amount.
Note that the second control unit 27 is configured such that when the abnormality detection unit 20 detects an abnormality and the current detected by the first current detector 25 indicates charging from the load 13 to the power storage unit 19, the electric double layer The second power converter 23 may be controlled to charge the capacitor 24. Further, the second control unit 27 sets the charging voltage of the electric double layer capacitor 24 to a predetermined value when the current detected by the first current detector 25 indicates the discharge from the power storage unit 19 to the load 13. You may control the 2nd power converter 23 so that it may discharge.

  As described above, according to the present embodiment, the capacity of the electric double layer capacitor 24 that can be rapidly charged only needs to be charged during the backup operation, and can be reduced to about half. Thereby, the shortcoming of the storage battery 22 that cannot be quickly charged can be overcome by connecting the electric double layer capacitor 24 that can be rapidly charged. Further, the capacity of the electric double layer capacitor 24 that can be rapidly charged can be reduced, and the cost and size can be reduced.

  FIG. 2 is a block diagram showing the power storage unit 19. The power storage unit 19 includes connection terminals 30 and 31 connected to the DC side of the first power converter 18, a wiring 32 from the connection terminal 30, and a wiring 33 from the connection terminal 31. Is connected to a storage battery 22. The wiring 32 is connected to the connection terminal 34 of the second power converter 23, and the wiring 33 is connected to the connection terminal 35 of the second power converter 23. The electric double layer capacitor 24 is connected to the connection terminals 36 and 37 of the second power converter 23. The wiring 32 is provided with a first current detector 25 that detects a current flowing through the wiring 32, that is, a current flowing through the power storage unit 19, and an electric double layer is provided between the storage battery 22 and the connection terminal 34. A second current detector 26 for detecting the current flowing through the capacitor 24 is provided.

  The power storage unit 19 includes a second control unit 27. The second control unit 27 includes a deviation calculating unit 38 that calculates a deviation between the current value detected by the first current detector 25 and the current value detected by the second current detector 26, and the deviation is A PI control unit 39 that performs PI control based on this, a voltage detection unit 40 that detects the voltage of the electric double layer capacitor 24, and a deviation calculation that calculates a deviation between the voltage value detected by the voltage detection unit 40 and the reference voltage Vc Unit 41 and a PI control unit 42 that performs PI control based on the deviation. The second control unit 27 detects whether the current is discharging from the power storage unit 19 or charging based on the current value detected by the first current detector 25, and based on the detected value. A switch control unit 45 is provided that controls a switch 44 that selects whether the output from the PI control unit 39 is connected to the PWM control unit 43 or the output from the PI control unit 42 is connected to the PWM control unit 43.

  The second power converter 23 includes switching elements 47 and 48 including a reactor 46 and a diode, and constitutes a bidirectional chopper circuit that performs step-up or step-down. In the second power converter 23, the switching from the electric double layer capacitor 24 to the load 13 or the electric power from the load 13 is controlled by controlling on / off of the switching elements 47 and 48 based on the signal from the PWM control unit 43. It controls whether the multilayer capacitor 24 is charged.

A specific control method in the uninterruptible power supply according to this embodiment by the second control unit 27 will be described.
(1) The current flowing through the second power converter 23 is detected by the second current detector 26 by detecting the current of the line connected to the DC side of the first power converter 18 by the first current detector 25. And the current flowing through the storage battery 22 is calculated by the deviation calculation unit 38.
(2) The switch control unit 45 detects that the current detected by the first current detector 25 is in the charging direction during the backup operation (when a power failure or the like is detected), and sets the switch 44 to 1 Connect to.
(3) The PI control unit 39 allows the current to flow using the second power converter 23 and the electric double layer capacitor 24 so that the deviation calculated by the deviation calculation unit 38 becomes zero.
(4) When the current detected by the first current detector 25 detects the discharge direction, the switch control unit 45 connects the switch 44 to 2.
(5) The PI control unit 42 calculates the deviation between the voltage detected by the voltage detection unit 40 of the electric double layer capacitor 24 and the specified amount Vc by the deviation calculation unit 41 and controls the deviation to be zero. Using the second power converter 23, the voltage of the electric double layer capacitor 24 is discharged to a predetermined value Vc.
(6) The same operation as (5) is performed when the switch control unit 45 detects normal operation (when power failure or the like is recovered).

  Next, the operation of the uninterruptible power supply according to the first embodiment configured as described above will be described in detail with reference to the flowchart shown in FIG.

Step S <b> 11: First, AC power is supplied to the load 13 via the AC switch 15 when the AC power supply 11 is normal.
Step S12: Next, the abnormality detection unit 20 determines an abnormality of the AC power supply 11 as to whether or not the AC power supply 11 has undergone a power failure or the like.
Step S13: When the AC power supply 11 becomes a power failure or the like, the first control unit 21 sends a detection signal to the AC switch 15 and the first power converter 18.
Step S14: The AC switch 15 is turned off.
Step S15: The first power converter 18 discharges the power storage unit 19 based on the control signal from the first control unit 21. At this time, the power storage unit 19 is controlled by the first control unit 21. Thereby, the first power converter 18 continues to supply stable AC power to the load 13. When there is regenerative power from the load 13, the first power conversion unit 18 supplies the regenerative power to the power storage unit 19.
Step S16: The abnormality detection unit 20 determines whether or not the AC power supply 11 is normal. When it is not normal, step S15 is continued. If normal, the process returns to step S11.

  Next, comparing costs, it will be described that the inventive device can add a function that can absorb regenerative power in about half of the conventional device.

  As a condition, let us consider what has the ability to discharge 80 kW for 5 seconds and the ability to absorb regenerative power of 40 kW for 2 seconds. At this time, in this embodiment, since the second power converter 23 is provided, the working voltage range of the electric double layer capacitor can be wider than the conventional 400V to 300V, and 400V to 200V. To do. When energy calculation is performed, the discharge energy is 80 kW × 5 sec = 400 kJ, and the absorbed energy is 40 kW × 2 sec = 80 kJ.

  In the uninterruptible power supply 10 of this embodiment, since the discharge energy 400 kJ is supplied from the storage battery 22, the energy that can be stored in the working voltage range of 400 V to 200 V of the electric double layer capacitor may be 80 KJ. Therefore, the required capacity is 80k = 0.5C (400 ^ 2-200 ^ 2) and C = 80k × 2 ÷ (400 ^ 2-200 ^ 2) = 1.33F unlike the conventional one. become. Therefore, the cost is 400V to 200V, 1.3F electric double layer capacitor is about 500,000 yen, lead storage battery 500,000 yen, the second power converter 23 is 1 million yen, a total of 2 million yen It will be.

  As described above, it is possible to provide an uninterruptible power supply device that has a function of backing up at low cost for a long time and a function of absorbing regenerative power from a load.

  FIG. 4 is a block diagram showing the configuration of the uninterruptible power supply according to the second embodiment of the present invention. The difference of the second embodiment from the first embodiment is that it is an always-inverter power supply system. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. . The uninterruptible power supply 50 converts an AC input terminal 12 for connecting the AC power supply 11, an AC output terminal 14 for connecting the load 13, and AC power supplied from the AC power supply 11 into DC power. AC / DC converter 51 to be supplied to DC link unit 52, power storage unit 19 connected to DC link unit 52 via first power converter (bidirectional DC / DC converter) 57, and AC / DC converter 51 A DC / AC converter 53 that converts DC power supplied from the power storage unit 19 to the DC link unit 52 via the first power converter 57 into desired AC power and supplies the AC power to the load 13; and the AC input terminal 12 An abnormality detection unit 20 that detects whether or not the AC voltage of the AC power supply 11 input from is abnormal, and when the abnormality detection unit 20 detects an abnormality, the AC / DC converter 51 is turned off, It includes a first control unit 54 for controlling the first power converter 57.

  The power storage unit 19 includes the same device as that described in the first embodiment.

  The AC / DC converter 51 converts AC power supplied from the AC power supply 11 into DC power and supplies the DC power to the DC link unit 52. The DC / AC converter 53 converts the DC power supplied to the DC link unit 52 into desired AC power and supplies it to the load 13.

  The first DC terminal 55 of the first power converter 57 is connected to the DC link unit 52 that connects the DC output terminal of the AC / DC converter 51 and the DC input terminal of the DC / AC converter 53. The power storage unit 19 is connected to the second DC terminal 56 of the first power converter 57, and the first power converter 57 supplies power bidirectionally between the power storage unit 19 and the DC link unit 56. The power storage unit 19 is charged and discharged.

  When the abnormality detection unit 20 detects an abnormality such as a power failure of the AC power supply 11, the first control unit 54 sends a detection signal to the AC / DC converter 51 and the first power converter 57.

  Based on the control signal from the first control unit 54, the first power converter 57 switches the power storage unit 19 from charging to discharging when the AC power supply 11 has a power failure or the like, and is stored in the power storage unit 19. Electric power is supplied to the DC link unit 52. In addition, the regenerative power from the load 13 is supplied to the power storage unit 19.

  Next, the operation of the uninterruptible power supply according to the second embodiment configured as described above will be described in detail with reference to the flowchart shown in FIG.

Step S21: First, when the AC power supply 11 is normal, AC power is input to the AC / DC converter 51. The AC / DC converter 51 converts the AC power into DC power, and the DC power is converted into the DC / AC converter. The desired AC power is converted by 53 and supplied to the load 13.
Step S22: Next, the abnormality detection unit 20 determines whether the AC power supply 11 is abnormal or not, whether or not the AC power supply 11 has failed.
Step S23: When the AC power supply 11 has a power failure or the like, the first control unit 54 sends a detection signal to the AC / DC converter 51 and the first power converter 57.
Step S24: The AC / DC converter 51 stops its operation.
Step S25: When the AC power supply 11 has a power failure or the like, the first power converter 57 switches the power storage unit 19 from charging to discharging based on the control signal from the first control unit 54. The accumulated power is supplied to the DC link unit 52. As a result, the DC / AC converter 53 continues to supply stable AC power to the load 13. When there is regenerative power from the load 13, the first power converter 57 supplies the regenerative power to the power storage unit 19.
Step S26: The abnormality detection unit 20 determines whether or not the AC power supply 11 is normal. When AC power supply 11 is abnormal, step S25 is continued. If the determination is normal, the process returns to step S21.

  Thus, according to the uninterruptible power supply 50 according to the second embodiment, it is possible to provide an uninterruptible power supply that has an inexpensive and long-time backup function and a function that can absorb regenerative power from a load.

  In the above embodiment, the second energy storage and storage element has been described as being the electric double layer capacitor 24, but a flywheel power storage device can be used. FIG. 6 is a diagram showing a flywheel power storage device. When this is used, an inverter 61 having connection terminals 62 and 63 is connected to the connection terminals 36 and 37 of the second power converter 23 shown in FIG. 2 and the flywheel power connected to the inverter 61 is connected. A storage device 60 is connected. Thereby, the same effect as when an electric double layer capacitor is used can be obtained. The inverter used at this time can be configured as a switching circuit having a three-phase bridge configuration using a conventional semiconductor switching element such as a transistor.

  In the above embodiment, the first control unit 21 and the second control unit 27 are provided. However, the function of the first control unit 21 and the function of the second control unit 27 are performed by one control unit. You may make it have.

  Furthermore, although the first power converter 57 is provided in the second embodiment, the power storage unit 19 may be directly connected to the DC link unit 52 without providing the first power converter 57. The AC / DC converter 51 may be a diode rectifier circuit having a bridge configuration.

  The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely schematically shown to the extent that the present invention can be understood and implemented, and the numerical values and the compositions (materials) of the respective components Is just an example. Therefore, the present invention is not limited to the described embodiments, and can be variously modified without departing from the scope of the technical idea shown in the claims.

  The uninterruptible power supply according to the present invention is used as an uninterruptible power supply that drives a motor or the like.

DESCRIPTION OF SYMBOLS 10 Uninterruptible power supply 11 AC power supply 12 AC input terminal 13 Load 14 AC output terminal 15 AC switch 16 AC terminal 17 DC terminal 18 1st power converter 19 Power storage part 20 Abnormality detection part 21 1st control part 22 Storage battery 23 Second power converter 24 Electric double layer capacitor 25 First current detector 26 Second current detector 27 Second controller

Claims (9)

AC input terminal for connecting AC power supply,
AC output terminal for connecting the load,
An AC switch connected between the AC input terminal and the AC output terminal;
A first power converter having an AC terminal and a DC terminal, wherein the AC terminal is connected to the AC switch on the AC output terminal side;
Power storage means connected to the DC terminal of the first power converter;
An abnormality detecting means for detecting whether or not the AC voltage input from the AC input terminal is abnormal;
A first control means for turning off the AC switch and controlling the first power converter when the abnormality detection means detects an abnormality; and
The power storage means includes a first energy storage and storage element and a second energy storage and storage for absorbing regenerative power connected in parallel with the first energy storage and storage element via a second power converter. Element, current detection means for detecting a current flowing through the power storage means, and second control means for controlling the second power converter based on a detection current from the current detection means. An uninterruptible power supply. AC input terminal for connecting AC power supply,
AC output terminal for connecting the load,
An AC / DC converter that converts AC power input from the AC input terminal into DC power and outputs the DC power to the DC link unit;
A DC / AC converter that converts the DC power input from the DC link unit into another AC power and outputs the AC power to the AC output terminal;
A first power converter having a first DC terminal and a second DC terminal, wherein the first DC terminal is connected to the DC link unit;
Power storage means connected to the second DC terminal of the first power converter;
An abnormality detecting means for detecting whether or not the AC voltage input from the AC input terminal is abnormal;
A first control means for turning off the AC / DC converter and controlling the first power converter when the abnormality detection means detects an abnormality;
The power storage means includes a first energy storage and storage element and a second energy storage and storage for absorbing regenerative power connected in parallel with the first energy storage and storage element via a second power converter. Element, current detection means for detecting a current flowing through the power storage means, and second control means for controlling the second power converter based on a detection current from the current detection means. An uninterruptible power supply.   The second control means detects the second energy storage and storage element when the abnormality detection means detects an abnormality and the detected current from the current detection means indicates charging from the load to the power storage means. The uninterruptible power supply according to claim 1 or 2, wherein the second power converter is controlled so as to be charged.   The second control means discharges the charging voltage of the second energy storage and storage element to a predetermined value when the detected current from the current detection means indicates discharge from the power storage means to the load. The uninterruptible power supply according to any one of claims 1 to 3, wherein the second power converter is controlled. The power storage means includes a first current detector as the current detection means, and a second current detector that detects a current flowing through the second energy storage and storage element,
The second control means detects the second energy storage when the abnormality detection means detects an abnormality and the detected current from the first current detector indicates charging from the load to the power storage means. In order to charge the storage element, the second power converter is controlled so that the difference between the detected current from the first current detector and the detected current from the second current detector becomes zero. The uninterruptible power supply according to claim 1 or 2.   When the detection current from the first current detector as the current detection means indicates the discharge from the power storage means to the load, the second control means determines the charging voltage of the second energy storage and storage element. The uninterruptible power supply according to any one of claims 1, 2, and 5, wherein the second power converter is controlled to discharge until a predetermined value is reached.   The uninterruptible power supply according to any one of claims 1 to 6, wherein the first energy storage and storage element is a storage battery.   The uninterruptible power supply according to any one of claims 1 to 7, wherein the second energy storage and storage element is an electric double layer capacitor.   The uninterruptible power supply according to any one of claims 1 to 7, wherein the second energy storage and storage element is a flywheel power storage device.

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