Uninterruptible Power Supply System

Abstract

To provide an uninterruptible power supply system which can efficiently charge a power storage device.SOLUTION: An uninterruptible power supply system includes first and second uninterruptible power supply devices connected in parallel to an AC load. Each of the first and second uninterruptible power supply devices includes: a power conversion circuit for converting power from an AC power supply; and a bypass circuit arranged in parallel with the power conversion circuit to supply power from a bypass input power supply. A power storage device is provided in common for the power conversion circuits of the first and second uninterruptible power supply devices to supply power to the AC load in the case of power failure of the AC power supply. The power storage device can be charged at high speed or at low speed. When power is supplied to the AC load from one power conversion circuit of the first or second uninterruptible power supply device, charging the power storage device from one power conversion circuit of the first or second uninterruptible power supply device is stopped, and the power storage device is charged at high speed from another power conversion circuit of the first or second uninterruptible power supply device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an uninterruptible power supply system including a plurality of uninterruptible power supply devices. [Background technology]

[0002] 2. Description of the Related Art Conventionally, uninterruptible power supplies (hereinafter simply referred to as UPS) have been used as power sources for important loads such as computers, which cannot tolerate even momentary power outages.

[0003] Continuous power supply from the UPS power supply is required during normal operation 24 hours a day, 365 days a year, as well as during inspections.

[0004] In this regard, a common standby uninterruptible power supply system has been disclosed in which two uninterruptible power supply devices are provided in parallel (see Patent Document 1).

[0005] With this configuration, even if one uninterruptible power supply unit breaks down or is undergoing inspection, the other uninterruptible power supply unit can continue to supply power (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-312371 Summary of the Invention [Problem to be solved by the invention]

[0007] On the other hand, the charging method for the power storage device connected to the uninterruptible power supply is fixed, and there is a problem that further improvement in efficiency is required.

[0008] An object of the present disclosure is to solve the above-mentioned problems and to realize an uninterruptible power supply system capable of efficiently charging a power storage device. [Means for solving the problem]

[0009] According to one embodiment, an uninterruptible power supply system includes first and second uninterruptible power supplies connected in parallel to an AC load. Each of the first and second uninterruptible power supplies includes a power conversion circuit that converts power from an AC power source and a bypass circuit that is connected in parallel to the power conversion circuit and supplies power from a bypass input power source. The uninterruptible power supply system further includes a power storage device that is connected in common to the power conversion circuits of the first and second uninterruptible power supplies and supplies power to the AC load in the event of a power outage in the AC power source. The power storage device is configured to be capable of fast or slow charging. When power is supplied to the AC load from the power conversion circuit of one of the first and second uninterruptible power supplies, charging of the power storage device from the power conversion circuit of one of the first and second uninterruptible power supplies is stopped, and the power storage device is fast charged from the power conversion circuit of the other of the first and second uninterruptible power supplies.

[0010] Preferably, when power is supplied to an AC load from one of the power conversion circuits of the first and second uninterruptible power supplies, if the other of the power conversion circuits of the first and second uninterruptible power supplies fails, the storage device is charged at a low rate from the power conversion circuit of one of the first and second uninterruptible power supplies.

[0011] Preferably, the power conversion circuit includes an inverter connected to an AC power supply and converting a voltage of the AC power supply into a DC voltage, a converter connected to the inverter and converting the DC voltage into an AC voltage, and a chopper circuit connected in parallel with the inverter and to the converter and adjusting the voltage level of the DC voltage to be supplied to the power storage device. When power is supplied to an AC load from one of the power conversion circuits of the first and second uninterruptible power supplies, the supply of DC voltage from the chopper circuit of one of the power conversion circuits of the first and second uninterruptible power supplies to the power storage device is stopped, and when power is supplied to the AC load from one of the power conversion circuits of the first and second uninterruptible power supplies, the first DC voltage is supplied to the power storage device from the chopper circuit of the other of the power conversion circuits of the first and second uninterruptible power supplies.

[0012] According to another embodiment, an uninterruptible power supply system includes an uninterruptible power supply that supplies power to an AC load and an uninterruptible backup power supply that is used in the event of a failure of the uninterruptible power supply. The uninterruptible power supply includes a power conversion circuit that converts power from an AC power source and a first bypass circuit that is provided in parallel with the power conversion circuit and supplies power from the uninterruptible backup power supply. The uninterruptible backup power supply includes a backup power conversion circuit that converts power from the AC power source and a backup bypass circuit that is provided in parallel with the backup power conversion circuit and supplies power from a bypass input power source. The uninterruptible power supply system further includes a power storage device that is provided in common with the power conversion circuit and the backup power conversion circuit and supplies power to the AC load in the event of a power outage of the AC power source. The power storage device is configured to be capable of fast or slow charging. When power is supplied to the AC load from the power conversion circuit, the power storage device is fast charged from the backup power conversion circuit. When power is supplied to the AC load from the first bypass circuit, the power storage device is slow charged from the backup power conversion circuit.

[0013] Preferably, the power conversion circuit includes a first inverter connected to the AC power supply and converting a voltage of the AC power supply into a DC voltage, a first converter connected to the first inverter and converting the DC voltage into an AC voltage, and a first chopper circuit connected in parallel with the first inverter to the first converter and adjusting a voltage level of the DC voltage supplied to the power storage device. The standby power conversion circuit includes a second inverter connected to the AC power supply and converting a voltage of the AC power supply into a DC voltage, a second converter connected to the second inverter and converting the DC voltage into an AC voltage, and a second chopper circuit connected in parallel with the first inverter to the first converter and adjusting a voltage level of the DC voltage supplied to the power storage device. When power is supplied from the power conversion circuit to the AC load, a first voltage is supplied from the second chopper circuit of the standby power conversion circuit to the power storage device, and when power is supplied from the first bypass circuit to the AC load, a second voltage lower than the first voltage is supplied from the second chopper circuit of the standby power conversion circuit to the power storage device.

[0014] Preferably, when power is supplied from the power conversion circuit to the AC load, the first chopper circuit is set to a state in which charging of the power storage device is stopped. [Effects of the Invention]

[0015] The uninterruptible power supply system of the present disclosure is capable of efficiently charging the power storage device. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram illustrating a circuit configuration of an uninterruptible power supply standby system according to a first embodiment. [Figure 2] FIG. 4 is a table illustrating a charge command of the control circuit based on the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating a charging state (part 1) of the uninterruptible power supply standby system according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating a charging state (part 2) of the uninterruptible power supply standby system according to the first embodiment. [Figure 5] FIG. 10 is a diagram illustrating a charging state (part 3) of the uninterruptible power supply standby system according to the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating the circuit configuration of an uninterruptible power supply standby parallel system according to a second embodiment. [Figure 7] FIG. 10 is a table illustrating a charge command of a control circuit according to the second embodiment. [Figure 8] FIG. 10 is a diagram illustrating a charging state (part 1) of the uninterruptible power supply standby parallel system according to the second embodiment. [Figure 9] FIG. 10 is a diagram illustrating a charging state (part 2) of the uninterruptible power supply standby parallel system according to the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating a charging state (part 3) of the uninterruptible power supply standby parallel system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment will be described with reference to the drawings. In this embodiment, an uninterruptible power supply system (hereinafter referred to as UPS (Uninterruptible Power Supply)) will be described as an example of a power supply system.

[0018] (Embodiment 1) In the first embodiment, a configuration of an uninterruptible power supply continuous standby system will be described in which one of a plurality of uninterruptible power supply devices is used as a standby uninterruptible power supply device.

[0019] Fig. 1 is a diagram illustrating the circuit configuration of an uninterruptible power supply standby system according to embodiment 1. As shown in Fig. 1, the uninterruptible power supply standby system includes an uninterruptible power supply 1B that supplies power to a load, an uninterruptible backup power supply 1A that is used in the event that uninterruptible power supply 1B fails, and a power storage device 10B that is provided corresponding to uninterruptible backup power supply 1A and uninterruptible power supply 1B and serves as an energy storage unit.

[0020] In this example, we will explain the case where an uninterruptible power supply unit 1A is provided as a spare (backup) for an uninterruptible power supply unit 1B, but this is not limited to one, and the configuration may also be such that an uninterruptible power supply unit 1A is provided for multiple uninterruptible power supplies.

[0021] The uninterruptible backup power supply 1A and the uninterruptible power supply 1B basically have the same configuration.

[0022] The uninterruptible standby power supply 1A and the uninterruptible power supply 1B include rectifiers 3A and 3B that convert AC input to DC input, inverters 4A and 4B that convert DC input to AC input, DC input circuit breakers 7A and 7B, chopper circuits 5A and 5B connected to the inverters 4A and 4B in parallel with the rectifiers 3A and 3B, and control circuits 9A and 9B that control the internal operation of the power conversion circuits, switches, etc. according to instructions from the control circuits 9A and 9B.

[0023] The DC input circuit breaker 7A is provided between the chopper circuit 5A and the power storage device 10B. The DC input circuit breaker 7B is provided between the chopper circuit 5B and the power storage device 10B.

[0024] The power storage device 10B is provided in common with the power conversion circuits of the uninterruptible power supply 1B and the uninterruptible backup power supply 1 A. The power storage device 10B includes a storage battery 12B.

[0025] The uninterruptible backup power supply 1A and the uninterruptible power supply 1B include a bypass circuit arranged in parallel with the power conversion circuit consisting of the forward converters 3A, 3B and the reverse converters 4A, 4B so as to obtain continuous UPS output to the load even if a failure occurs in the power conversion circuit.

[0026] The uninterruptible standby power supply 1A and the uninterruptible power supply 1B have bypass side switches 8A, 8B each made up of a thyristor and a contactor, and can be switched without interruption by turning on the bypass side switches 8A, 8B.

[0027] Uninterruptible power supply 1B receives AC input from commercial power supply 16B. The AC input is converted to DC by rectifier 3A and then converted back to AC by inverter 4B. Inverter 4B always supplies a stable UPS output to the load. Chopper circuit 5B is connected in parallel with rectifier 3B via DC input breaker 7B. When a power outage occurs in commercial power supply 16B, DC energy from power storage device 10B, which is an energy storage unit, is supplied to inverter 4B via DC input breaker 7B and chopper circuit 5B. This allows the UPS output of uninterruptible power supply 1B to be continuously supplied to the load.

[0028] Power to the bypass circuit of the uninterruptible power supply 1B is supplied from the uninterruptible backup power supply 1A.

[0029] The uninterruptible backup power supply 1A receives AC input from a commercial power supply 16A. The AC input is converted to DC by the rectifier 3A and then converted back to AC by the inverter 4A, making it possible to supply a constantly stable UPS output. The energy storage unit, a power storage device 10B, is connected in parallel to the rectifier 3A via a DC input circuit breaker 7A and a chopper circuit 5A. The DC input circuit breaker 7A is also connected to the power storage device 10B.

[0030] When a power outage occurs in commercial power supply 16A, DC energy from power storage device 10B, which is an energy storage unit, is supplied to inverter 4A via DC input circuit breaker 7B and chopper circuit 5B. This allows the UPS output of uninterruptible standby power supply 1A to be continuously supplied to the bypass circuit of uninterruptible power supply 1B.

[0031] In order to ensure continuous UPS output even in the event of a failure in the rectifier 3A or inverter 4A, a bypass circuit is provided in parallel with the commercial power supply 16A, which supplies power using the bypass input power supply 15A as input. The bypass circuit has a bypass-side switch 8A consisting of a thyristor and a contactor, and switching is performed without interruption by turning on the bypass-side switch 8A. The bypass input power supply 15A is a commercial power supply, just like the normal AC input.

[0032] The control circuit 9A and the control circuit 9B constantly exchange information relating to the inverter power supply signal, and also receive inputs of a regular machine setting signal and a standby machine setting signal.

[0033] As an example, a regular unit setting signal is input to control circuit 9B, and a standby unit setting signal is input to control circuit 9A. In this state, uninterruptible power supply 1B operates as the regular unit, and uninterruptible standby power supply 1A operates as the standby unit.

[0034] In the conventional configuration, for example, charging of power storage device 10B is performed from uninterruptible power supply 1B operating as a regular device via chopper circuit 5B and DC input breaker 7B.

[0035] In this state, power storage device 10B is being charged at a low rate because power is also being supplied to the load.

[0036] However, uninterruptible power supply 1A is on standby as a backup device, and it is possible to further improve the efficiency of charging power storage device 10B.

[0037] FIG. 2 is a table illustrating a charge command from the control circuit based on the first embodiment. Referring to FIG. 2, control circuits 9A and 9B output charge commands to chopper circuits 5A and 5B when a predetermined condition is met.

[0038] Specifically, the control circuits 9A, 9B receive the standby inverter setting signal and, when the inverter is set to the regular inverter, output a high-rate charging command to the chopper circuits 5A, 5B.

[0039] As an example, the control circuit 9A receives a standby inverter setting signal and also receives a regular inverter setting signal as an inverter power supply signal. This causes the control circuit 9A to output a high-rate charging command to the chopper circuit 5A. Based on the high-rate charging command, the chopper circuit 5A sets the DC voltage to a first voltage (>second voltage) and charges the power storage device 10B. This enables rapid charging of the power storage device 10B.

[0040] Meanwhile, the control circuit 9B receives the normal machine setting signal and also receives the normal machine inverter setting signal as an inverter power supply signal. As a result, the control circuit 9B outputs a charge stop command to the chopper circuit 5B. The inverter power supply signals are, for example, the same and are exchanged between the two devices. If there is no signal input from the other device, it can be determined that the device in question is faulty.

[0041] As another example, the control circuit 9A receives a standby unit setting signal and also receives a standby unit inverter setting signal as an inverter power supply signal. This causes the control circuit 9A to output a low-rate charging command to the chopper circuit 5A. The chopper circuit 5A sets the DC voltage to a second voltage based on the low-rate charging command, and charges the power storage device 10B.

[0042] As another example, when control circuit 9A receives a standby unit setting signal and there is no input of an inverter setting signal from a regular unit, control circuit 9A outputs a low-rate charging command to chopper circuit 5A. Chopper circuit 5A sets the DC voltage to a second voltage based on the low-rate charging command and charges power storage device 10B.

[0043] As yet another example, the control circuit 9B receives a regular unit setting signal, and when there is no input of an inverter setting signal from the standby unit, the control circuit 9B outputs a low-rate charging command to the chopper circuit 5B.

[0044] FIG. 3 is a diagram illustrating a charging state (part 1) of the uninterruptible power supply regular standby system according to the first embodiment. As shown in FIG. 3, the control circuit 9A receives a standby unit setting signal and also receives an input of a regular unit inverter setting signal as an inverter power supply signal. This causes the control circuit 9A to output a high-rate charging command to the chopper circuit 5A. Based on the high-rate charging command, the chopper circuit 5A sets the DC voltage to a first voltage (>second voltage) and executes charging of the power storage device 10B. This enables rapid charging of the power storage device 10B.

[0045] On the other hand, the control circuit 9B receives the normal-use setting signal and also receives the normal-use inverter setting signal as an inverter power supply signal. As a result, the control circuit 9B outputs a charge stop command to the chopper circuit 5B. By outputting a high-rate charge command to the chopper circuit 5A, rapid charging is performed from the uninterruptible standby power supply 1A to the power storage device 10B. On the other hand, by outputting a charge stop command to the chopper circuit 5B, the uninterruptible power supply 1B does not charge the power storage device 10B, and can supply stable power to the load.

[0046] 4 is a diagram illustrating the charging state (part 2) of the uninterruptible power supply continuous backup system according to embodiment 1. As shown in FIG. 4, when an abnormality occurs in uninterruptible power supply 1B, power is supplied from uninterruptible backup power supply 1A to the load via the bypass circuit.

[0047] As an example, if an abnormality occurs in the uninterruptible power supply 1B, the control circuit 9B switches the inverter power supply signal from the normal inverter setting signal to the standby inverter setting signal. The control circuit 9A receives the standby inverter setting signal and also receives the standby inverter setting signal as the inverter power supply signal. This causes the control circuit 9A to output a low-rate charging command to the chopper circuit 5A. Based on the low-rate charging command, the chopper circuit 5A sets the DC voltage to a second voltage (<first voltage) and charges the power storage device 10B. This causes the power storage device 10B to be slowly charged.

[0048] On the other hand, the control circuit 9B receives the regular inverter setting signal and also receives the standby inverter setting signal as an inverter power supply signal, and thereby outputs a charge stop command to the chopper circuit 5B.

[0049] A low-rate charging command is output to chopper circuit 5A, whereby low-speed charging from uninterruptible power supply 1A to power storage device 10B is carried out.

[0050] Alternatively, if a failure occurs in the uninterruptible power supply 1B, the inverter power supply signal from the control circuit 9B to the control circuit 9A of the uninterruptible backup power supply 1B may stop.

[0051] Control circuit 9A determines that uninterruptible power supply 1B has failed when control circuit 9B does not input an inverter power supply signal as an inverter power supply signal. As a result, control circuit 9A outputs a low-rate charge command to chopper circuit 5A. Based on the low-rate charge command, chopper circuit 5A sets the DC voltage to a second voltage (<first voltage) and charges power storage device 10B. As a result, low-speed charging is performed on power storage device 10B.

[0052] A low-rate charging command is output to chopper circuit 5A, whereby low-speed charging from uninterruptible power supply 1A to power storage device 10B is carried out.

[0053] Fig. 5 is a diagram illustrating a charging state (part 3) of the uninterruptible power supply regular backup system according to embodiment 1. As shown in Fig. 5, when a failure occurs in uninterruptible backup power supply 1A, power is supplied to the load from uninterruptible power supply 1B, and slow charging is performed on power storage device 10B.

[0054] As an example, the control circuit 9B receives a normal machine setting signal and also receives an input of a normal machine inverter setting signal as an inverter power supply signal.

[0055] If a failure occurs in the uninterruptible power supply 1A, there is a possibility that the inverter power supply signal from the control circuit 9A to the control circuit 9B of the uninterruptible backup power supply 1A may stop.

[0056] Control circuit 9B determines that uninterruptible power supply 1A has failed when control circuit 9A does not input an inverter power supply signal as an inverter power supply signal. As a result, control circuit 9B outputs a low-rate charge command to chopper circuit 5B. Based on the low-rate charge command, chopper circuit 5B sets the DC voltage to a second voltage (<first voltage) and charges power storage device 10B. As a result, low-speed charging is performed on power storage device 10B.

[0057] A low-rate charging command is output to chopper circuit 5B, whereby low-speed charging from uninterruptible power supply 1B to power storage device 10B is carried out.

[0058] With the above system, when uninterruptible power supply 1B, the regular device, is operating normally, it is possible to rapidly charge power storage device 10B using uninterruptible standby power supply 1A, the standby device, thereby enabling efficient charging of power storage device 10B. On the other hand, when an abnormality or failure occurs in uninterruptible power supply 1B, it is possible to slowly charge power storage device 10B using uninterruptible standby power supply 1A, the standby device, thereby making it possible to secure discharge power from power storage device 10B in the event of a power outage. Furthermore, when uninterruptible standby power supply 1A fails, it is possible to slowly charge power storage device 10B using uninterruptible power supply 1B, the regular device, thereby making it possible to secure discharge power from power storage device 10B in the event of a power outage.

[0059] (Embodiment 2) In the second embodiment, a configuration of an uninterruptible power supply standby parallel system in which a plurality of uninterruptible power supply devices are connected in parallel will be described as a configuration of an uninterruptible power supply system.

[0060] Fig. 6 is a diagram illustrating the circuit configuration of an uninterruptible power supply standby parallel system according to embodiment 2. As shown in Fig. 6, the uninterruptible power supply standby parallel system includes uninterruptible power supplies 1C and 1D connected in parallel to supply power to a load, and a power storage device 10D that is provided corresponding to uninterruptible power supply 1C and uninterruptible power supply 1D and serves as an energy storage unit.

[0061] In this example, a case where two uninterruptible power supply devices 1C and 1D are provided will be described, but the number is not limited to two, and a configuration in which a plurality of uninterruptible power supply devices are provided in parallel may also be used.

[0062] The uninterruptible power supply 1C and the uninterruptible power supply 1D basically have the same configuration. Uninterruptible power supplies 1C and 1D each include a rectifier 3C, 3D that converts AC input to DC input, an inverter 4C, 4D that converts DC input to AC input, a DC input breaker 7C, 7D, a chopper circuit 5C, 5D connected to the inverter 4C, 4D in parallel with the rectifier 3C, 3D, and a control circuit 9C, 9D that controls the internal operation of the power conversion circuit, switches, etc. according to instructions from the control circuit 9C, 9D.

[0063] The DC input circuit breaker 7C is provided between the chopper circuit 5C and the power storage device 10D. The DC input circuit breaker 7D is provided between the chopper circuit 5D and the power storage device 10D.

[0064] The power storage device 10D is provided in common to the power conversion circuits of the uninterruptible power supply 1C and the uninterruptible power supply 1D. The power storage device 10D includes a storage battery 12D.

[0065] Uninterruptible power supply 1C and uninterruptible power supply 1D include a bypass circuit arranged in parallel with the power conversion circuit consisting of forward converters 3C, 3D and reverse converters 4C, 4D in order to obtain continuous UPS output to the load even if a failure occurs in the power conversion circuit.

[0066] The uninterruptible power supply 1C and the uninterruptible power supply 1D have bypass side switches 8C and 8D each made up of a thyristor and a contactor, and can be switched without momentary interruption by turning on the bypass side switches 8C and 8D.

[0067] Uninterruptible power supply 1C receives AC input from commercial power supply 16C. The AC input is converted to DC by rectifier 3C and then converted back to AC by inverter 4C. Inverter 4C constantly supplies a stable UPS output to the load. Chopper circuit 5C is connected in parallel with rectifier 3C via DC input circuit breaker 7C. When a power outage occurs in commercial power supply 16C, DC energy from power storage device 10D, which serves as an energy storage unit, is supplied to inverter 4C via DC input circuit breaker 7C and chopper circuit 5C. This allows the UPS output of uninterruptible power supply 1C to be continuously supplied to the load.

[0068] The uninterruptible power supply 1D receives AC input from a commercial power supply 16D. The AC input is converted to DC by a rectifier 3D and then converted back to AC by an inverter 4D. The inverter 4D always supplies a stable UPS output to the load. A chopper circuit 5D is connected in parallel with the rectifier 3D via a DC input breaker 7D. When a power outage occurs in the commercial power supply 16D, DC energy from the energy storage device 10D, which serves as an energy storage unit, is supplied to the inverter 4D via the DC input breaker 7D and the chopper circuit 5D. This allows the UPS output of the uninterruptible power supply 1D to be continuously supplied to the load.

[0069] The control circuits 9C and 9D constantly exchange information relating to the inverter power supply signal, and also receive inputs of a master device setting signal and a slave device setting signal.

[0070] As an example, a master device setting signal is input to control circuit 9C, and a slave device setting signal is input to control circuit 9D. In this state, uninterruptible power supply 1C operates as the master device, and uninterruptible power supply 1D operates as the slave device.

[0071] In the conventional configuration, for example, charging of power storage device 10D is performed from uninterruptible power supply 1C operating as a master device via chopper circuit 5C and DC input breaker 7C.

[0072] In this state, power storage device 10D is being charged at a low rate because power is also being supplied to the load.

[0073] However, the uninterruptible power supply 1D is on standby as a slave device, and it is possible to further improve the efficiency of charging the power storage device 10D.

[0074] FIG. 7 is a table illustrating a charge command from the control circuit according to the second embodiment. Referring to FIG. 7, control circuits 9C and 9D output charge commands to chopper circuits 5C and 5D when a predetermined condition is met.

[0075] Specifically, the control circuits 9C, 9D receive the slave device setting signal, and when the master device inverter is set and the slave device is normal, output a high-rate charging command to the chopper circuits 5C, 5D.

[0076] As an example, the control circuit 9D receives a slave device setting signal and also receives a master device inverter setting signal as an inverter power supply signal. This causes the control circuit 9D to output a high-rate charging command to the chopper circuit 5D. Based on the high-rate charging command, the chopper circuit 5D sets the DC voltage to a first voltage (>second voltage) and charges the power storage device 10D. This enables rapid charging of the power storage device 10D.

[0077] On the other hand, the control circuit 9C receives the master device setting signal and the master device inverter setting signal, and in response thereto, outputs a charge stop command to the chopper circuit 5C.

[0078] As another example, when control circuit 9C receives a master device setting signal and no inverter setting signal is input from a slave device, control circuit 9C outputs a low-rate charging command to chopper circuit 5C. Chopper circuit 5C sets the DC voltage to a second voltage based on the low-rate charging command and charges power storage device 10D.

[0079] As another example, control circuit 9D receives a slave device setting signal and also receives an input of the slave device inverter setting signal as an inverter power supply signal. Control circuit 9D then outputs a low-rate charging command to chopper circuit 5D. Chopper circuit 5D sets the DC voltage to a second voltage based on the low-rate charging command, and charges power storage device 10D.

[0080] As yet another example, the control circuit 9D receives a slave device setting signal, and when there is no input of an inverter setting signal from the master device, the control circuit 9D outputs a low-rate charging command to the chopper circuit 5D.

[0081] FIG. 8 is a diagram illustrating a charging state (part 1) of the uninterruptible power supply standby parallel system according to the second embodiment. As shown in FIG. 8, the control circuit 9D receives the slave device setting signal and also receives the master device inverter setting signal as an inverter power supply signal. This causes the control circuit 9D to output a high-rate charging command to the chopper circuit 5D. Based on the high-rate charging command, the chopper circuit 5D sets the DC voltage to a first voltage (>second voltage) and executes charging of the power storage device 10D. This enables rapid charging of the power storage device 10D.

[0082] Meanwhile, the control circuit 9C receives a master device setting signal and also receives an input of a master device inverter setting signal. As a result, the control circuit 9C outputs a charge stop command to the chopper circuit 5C. By outputting a high-rate charge command to the chopper circuit 5D, rapid charging from the uninterruptible power supply 1D to the power storage device 10D is performed. On the other hand, by outputting a charge stop command to the chopper circuit 5C, the uninterruptible power supply 1C does not charge the power storage device 10D, and can supply stable power to the load.

[0083] 9 is a diagram illustrating a charging state (part 2) of the uninterruptible power supply standby parallel system according to embodiment 2. As shown in FIG. 9, if an abnormality occurs in uninterruptible power supply 1D, control circuit 9D outputs a charging stop command to chopper circuit 5D. Furthermore, if an abnormality or failure occurs in uninterruptible power supply 1D, there is a possibility that the inverter power supply signal from control circuit 9D of uninterruptible power supply 1D to control circuit 9C of uninterruptible power supply 1C may stop.

[0084] The control circuit 9C determines an abnormality or failure of the uninterruptible power supply 1D when there is no inverter power supply signal input from the control circuit 9D as the inverter power supply signal. As a result, the control circuit 9C receives the master unit setting signal, and when there is no inverter setting signal input from the slave unit, it determines that there is an abnormality or failure of the slave unit and outputs a low-rate charging command to the chopper circuit 5C. Based on the low-rate charging command, the chopper circuit 5C sets the DC voltage to a second voltage (<first voltage) and executes charging of the power storage device 10D. As a result, slow charging is executed for the power storage device 10D.

[0085] A low-rate charging command is output to chopper circuit 5C, whereby low-speed charging from uninterruptible power supply 1C to power storage device 10D is carried out.

[0086] FIG. 10 is a diagram illustrating a charging state (part 3) of the uninterruptible power supply standby parallel system according to the second embodiment. As shown in FIG. 10, when an abnormality occurs in the uninterruptible power supply 1C, the control circuit 9C switches the inverter power supply signal from the master inverter setting signal to the slave inverter setting signal. The control circuit 9D receives the slave inverter setting signal and also receives the slave inverter setting signal as the inverter power supply signal. This causes the control circuit 9D to output a low-rate charging command to the chopper circuit 5D. The chopper circuit 5D sets the DC voltage to a second voltage based on the low-rate charging command and charges the power storage device 10D. This causes the power storage device 10D to be slowly charged.

[0087] Alternatively, if a failure occurs in the uninterruptible power supply 1C, the inverter power supply signal from the control circuit 9C to the control circuit 9D of the uninterruptible backup power supply 1C may stop.

[0088] Control circuit 9D determines that uninterruptible power supply 1C has failed when control circuit 9C does not input an inverter power supply signal as an inverter power supply signal. As a result, control circuit 9D outputs a low-rate charge command to chopper circuit 5D. Based on the low-rate charge command, chopper circuit 5D sets the DC voltage to a second voltage (<first voltage) and charges power storage device 10D. As a result, slow charging is performed on power storage device 10D.

[0089] A low-rate charging command is output to chopper circuit 5D, whereby uninterruptible power supply 1D performs low-speed charging of power storage device 10D.

[0090] With the above method, when uninterruptible power supply 1C is operating normally as the master device, it is possible to rapidly charge power storage device 10D using uninterruptible power supply 1D as the slave device, thereby enabling efficient charging of power storage device 10D. On the other hand, when an abnormality or failure occurs in uninterruptible power supply 1D, it is possible to slowly charge power storage device 10D using uninterruptible power supply 1C as the master device, thereby making it possible to ensure discharge power from power storage device 10D in the event of a power outage. Alternatively, when an abnormality or failure occurs in uninterruptible power supply 1C, it is possible to slowly charge power storage device 10D using uninterruptible power supply 1D as the slave device, thereby making it possible to ensure discharge power from power storage device 10D in the event of a power outage.

[0091] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0092] 1A Uninterruptible power supply unit, 1B, 1C, 1D Uninterruptible power supply unit, 3A, 3B, 3C, 3D Forward converter, 4A, 4B, 4C, 4D Reverse converter, 5A, 5B, 5C, 5D Triple circuit, 7A, 7B, 7C, 7D DC input circuit breaker, 8A, 8B, 8C, 8D Bipass side switch, 9A, 9B, 9C, 9D Control circuit, 10B, 10D Power storage device, 12B, 12D Battery, 15A Bipass input power supply, 16A, 16B, 16C, 16D Commercial power supply.

Claims

1. a first uninterruptible power supply and a second uninterruptible power supply connected in parallel to an AC load; Each of the first and second uninterruptible power supplies is a power conversion circuit that converts power from an AC power source; a bypass circuit provided in parallel with the power conversion circuit and supplying power from a bypass input power source; a power storage device provided in common to the power conversion circuits of the first and second uninterruptible power supplies, the power storage device supplying power to the AC load when the AC power supply is interrupted; The power storage device is provided so as to be capable of being charged at high speed or at low speed, when power is supplied to the AC load from the power conversion circuit of one of the first and second uninterruptible power supplies, charging of the power storage device from the power conversion circuit of one of the first and second uninterruptible power supplies is stopped, and high-speed charging of the power storage device is performed from the power conversion circuit of the other of the first and second uninterruptible power supplies, The power conversion circuit includes: an inverter connected to the AC power supply and converting a voltage of the AC power supply into a DC voltage; a converter connected to the inverter and converting the DC voltage into an AC voltage; a chopper circuit connected to the converter in parallel with the inverter and adjusting a voltage level of a DC voltage supplied to the power storage device, when power is supplied to the AC load from a power conversion circuit of one of the first and second uninterruptible power supplies, stopping the supply of DC voltage from a chopper circuit of the power conversion circuit of one of the first and second uninterruptible power supplies to the power storage device; an uninterruptible power supply system in which, when power is supplied to the AC load from the power conversion circuit of one of the first and second uninterruptible power supplies, a first DC voltage is supplied to the storage device from a chopper circuit of the other power conversion circuit of the first and second uninterruptible power supplies.

2. 2. The uninterruptible power supply system according to claim 1, wherein, when power is supplied to the AC load from a power conversion circuit of one of the first and second uninterruptible power supplies, if an abnormality or failure occurs in the power conversion circuit of the other of the first and second uninterruptible power supplies, the power storage device is charged at a low rate from the power conversion circuit of one of the first and second uninterruptible power supplies.

3. An uninterruptible power supply that supplies power to an AC load; an uninterruptible backup power supply that is used in the event of an abnormality or failure in the uninterruptible power supply; The uninterruptible power supply a power conversion circuit that converts power from an AC power source; a first bypass circuit provided in parallel with the power conversion circuit and supplying power from the uninterruptible standby power supply; The uninterruptible standby power supply device is a standby power conversion circuit that converts power from the AC power source; a standby bypass circuit provided in parallel with the standby power conversion circuit and supplying power from a bypass input power source; the power conversion circuit and the standby power conversion circuit are provided in common, and the power storage device supplies power to the AC load when the AC power supply is interrupted; The power storage device is provided so as to be capable of being charged at high speed or at low speed, When power is supplied from the power conversion circuit to the AC load, the power storage device is charged at high speed from the standby power conversion circuit, When power is supplied to the AC load from the first bypass circuit, the power storage device is charged at a low rate from the standby power conversion circuit, The power conversion circuit includes: a first inverter connected to the AC power supply and configured to convert a voltage of the AC power supply into a DC voltage; a first converter connected to the first inverter and configured to convert the DC voltage into an AC voltage; a first chopper circuit connected to the first converter in parallel with the first inverter and configured to adjust a voltage level of a DC voltage to be supplied to the power storage device; The auxiliary power conversion circuit includes: a second inverter connected to the AC power supply and configured to convert a voltage of the AC power supply into a DC voltage; a second converter connected to the second inverter and configured to convert the DC voltage into an AC voltage; a second chopper circuit connected to the first converter in parallel with the first inverter and configured to adjust a voltage level of a DC voltage to be supplied to the power storage device; when power is supplied from the power conversion circuit to the AC load, a first voltage is supplied from the second chopper circuit of the standby power conversion circuit to the power storage device; an uninterruptible power supply system, wherein when power is supplied to the AC load from the first bypass circuit, a second voltage lower than the first voltage is supplied to the power storage device from the second chopper circuit of the standby power conversion circuit.

4. An uninterruptible power supply system as described in claim 3, wherein when power is supplied from the power conversion circuit to the AC load, the first chopper circuit is set to a state in which charging to the storage device is stopped.

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