JP7743365B2 - Uninterruptible Power Supply System - Google Patents

Description

This disclosure relates to an uninterruptible power supply system equipped with multiple uninterruptible power supply devices.

Uninterruptible power supplies (hereafter simply referred to as UPS) have traditionally been used as power sources for critical loads such as computers, which cannot tolerate even momentary power outages.

Continual power supply from a UPS power source is required during normal operation 24 hours a day, 365 days a year, as well as during inspections.

In this regard, a common standby uninterruptible power supply system has been disclosed in which two uninterruptible power supply units are arranged in parallel (see Patent Document 1).

With this configuration, even if one uninterruptible power supply unit fails or is undergoing inspection, the other uninterruptible power supply unit can continue to supply power. (See Patent Document 1.)

Japanese Patent Application Laid-Open No. 2008-312371

However, the charging method for the storage device connected to the uninterruptible power supply is fixed, and there is a need for further efficiency improvements.

The purpose of this disclosure is to solve the above-mentioned problems and realize an uninterruptible power supply system that can efficiently charge a power storage device.

According to one embodiment, the 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.

Preferably, when power is supplied to an AC load from the power conversion circuit of one of the first and second uninterruptible power supplies, if the power conversion circuit of the other of the first and second uninterruptible power supplies fails, the power storage device is slowly charged from the power conversion circuit of one of the first and second uninterruptible power supplies.

Preferably, the power conversion circuit includes an inverter connected to an AC power source and converting the voltage of the AC power source into DC voltage; a converter connected to the inverter and converting the DC voltage into AC voltage; and a chopper circuit connected in parallel with the inverter and the converter and adjusting the voltage level of the DC voltage 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 an 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.

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 utilized 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.

Preferably, the power conversion circuit includes a first inverter connected to the AC power source and converting the voltage of the AC power source 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 the 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 source and converting the voltage of the AC power source 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 the 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.

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 to the power storage device is stopped.

The uninterruptible power supply system disclosed herein is capable of efficiently charging a power storage device.

1 is a diagram illustrating a circuit configuration of an uninterruptible power supply standby system according to a first embodiment. FIG. 4 is a table illustrating a charge command of a control circuit based on the first embodiment. FIG. 2 is a diagram illustrating a charging state (part 1) of the uninterruptible power supply standby system according to the first embodiment. FIG. 10 is a diagram illustrating a charging state (part 2) of the uninterruptible power supply standby system according to the first embodiment. FIG. 10 is a diagram illustrating a charging state (part 3) of the uninterruptible power supply standby system according to the first embodiment. FIG. 10 is a diagram illustrating the circuit configuration of an uninterruptible power supply standby parallel system according to a second embodiment. FIG. 10 is a table illustrating a charge command of a control circuit according to the second embodiment. FIG. 10 is a diagram illustrating a charging state (part 1) of the uninterruptible power supply standby parallel system according to the second embodiment. FIG. 10 is a diagram illustrating a charging state (part 2) of the uninterruptible power supply standby parallel system according to the second embodiment. FIG. 10 is a diagram illustrating a charging state (part 3) of the uninterruptible power supply standby parallel system according to the second embodiment.

The following describes an embodiment with reference to the accompanying drawings. In this example, an uninterruptible power supply system (hereinafter referred to as UPS) will be used as an example of a power supply system.

(Embodiment 1)
In the first embodiment, a configuration of an uninterruptible power supply system in a continuous standby state in which one of a plurality of uninterruptible power supply units is used as a standby uninterruptible power supply unit will be described.

Figure 1 is a diagram illustrating the circuit configuration of an uninterruptible power supply standby system based on embodiment 1. As shown in Figure 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 of a failure of uninterruptible power supply 1B, and a power storage device 10B that is provided in correspondence with uninterruptible backup power supply 1A and uninterruptible power supply 1B and serves as an energy storage unit.

In this example, we will explain the case where uninterruptible power supply unit 1A is provided as a backup for uninterruptible power supply unit 1B, but this is not limited to one, and a configuration in which uninterruptible power supply unit 1A is provided for multiple uninterruptible power supplies may also be used.

The configurations of uninterruptible backup power supply 1A and uninterruptible power supply 1B are basically the same.

Uninterruptible standby power supply 1A and 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 inverters 4A and 4B in parallel with rectifiers 3A and 3B, and control circuits 9A and 9B that control the internal components, respectively. They control the operation of the power conversion circuits, switches, etc. according to instructions from control circuits 9A and 9B.

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.

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 1A. The power storage device 10B includes a storage battery 12B.

Uninterruptible standby power supply 1A and uninterruptible power supply 1B include a bypass circuit arranged in parallel with the power conversion circuit, which is made up of rectifiers 3A and 3B and inverters 4A and 4B, to ensure continuous UPS output to the load even if a failure occurs in the power conversion circuit.

Uninterruptible backup power supply 1A and uninterruptible power supply 1B have bypass-side switches 8A and 8B, each consisting of a thyristor and a contactor, and switching can be performed without interruption by turning on bypass-side switches 8A and 8B.

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

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

The uninterruptible standby 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.

When a power outage occurs in commercial power supply 16A, DC energy from energy storage device 10B, which serves as the 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 continue being supplied to the bypass circuit of uninterruptible power supply 1B.

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 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.

Control circuits 9A and 9B constantly exchange information regarding the inverter power supply signal, and also receive inputs of a regular unit setting signal and a standby unit setting signal.

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

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

In this state, power was also being supplied to the load, so the storage device 10B was being charged at a low rate.

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

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 predetermined conditions are met.

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

As an example, the control circuit 9A receives a standby unit setting signal and also receives 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 the first voltage (> the second voltage) and charges the storage device 10B. This enables rapid charging of the storage device 10B.

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. This causes the control circuit 9B to output a charging 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.

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. Based on the low-rate charging command, the chopper circuit 5A sets the DC voltage to a second voltage and charges the storage device 10B.

As another example, when the control circuit 9A receives a standby unit setting signal and there is no inverter setting signal input from the regular unit, the control circuit 9A outputs 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 and charges the storage device 10B.

As another example, when the control circuit 9B receives a regular unit setting signal and no inverter setting signal is input from the backup unit, the control circuit 9B outputs a low-rate charging command to the chopper circuit 5B.

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

Meanwhile, control circuit 9B receives the normal unit setting signal and also receives the normal unit inverter setting signal as an inverter power supply signal. This causes control circuit 9B to output a charge stop command to chopper circuit 5B. By outputting a high-rate charge command to chopper circuit 5A, rapid charging is performed from uninterruptible standby power supply 1A to power storage device 10B. On the other hand, by outputting a charge stop command to chopper circuit 5B, uninterruptible power supply 1B does not charge power storage device 10B, allowing it to supply stable power to the load.

Figure 4 is a diagram illustrating the charging state (part 2) of the uninterruptible power supply standby system based on embodiment 1. As shown in Figure 4, if an abnormality occurs in uninterruptible power supply unit 1B, power is supplied to the load from uninterruptible power supply unit 1A via the bypass circuit.

As an example, if an abnormality occurs in uninterruptible power supply 1B, control circuit 9B switches the inverter power supply signal from the normal inverter setting signal to the standby inverter setting signal. 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 control circuit 9A to output a low-rate charging command to chopper circuit 5A. Based on the low-rate charging command, chopper circuit 5A sets the DC voltage to a second voltage (<first voltage) and charges power storage device 10B. This allows slow charging of power storage device 10B.

Meanwhile, the control circuit 9B receives the regular inverter setting signal and also receives the standby inverter setting signal as an inverter power supply signal. This causes the control circuit 9B to output a charging stop command to the chopper circuit 5B.

A low-rate charging command is output to the chopper circuit 5A, causing the uninterruptible power supply 1A to slowly charge the storage battery 10B.

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

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. This causes control circuit 9A to output a low-rate charging command to chopper circuit 5A. Based on the low-rate charging command, chopper circuit 5A sets the DC voltage to a second voltage (<first voltage) and charges power storage device 10B. This causes power storage device 10B to be slowly charged.

A low-rate charging command is output to the chopper circuit 5A, causing the uninterruptible power supply 1A to slowly charge the storage battery 10B.

Figure 5 is a diagram illustrating the charging state (part 3) of the uninterruptible power supply continuous standby system based on embodiment 1. As shown in Figure 5, when a failure occurs in uninterruptible standby power supply unit 1A, power is supplied to the load from uninterruptible power supply unit 1B, and slow charging is performed on power storage unit 10B.

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

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

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. This causes control circuit 9B to output a low-rate charging command to chopper circuit 5B. Based on the low-rate charging command, chopper circuit 5B sets the DC voltage to a second voltage (<first voltage) and charges power storage device 10B. This causes power storage device 10B to be slowly charged.

A low-rate charging command is output to chopper circuit 5B, causing uninterruptible power supply 1B to slowly charge power storage device 10B.

With the above method, when uninterruptible power supply 1B, the regular device, is operating normally, it is possible to rapidly charge power storage device 10B using uninterruptible backup power supply 1A, the backup device, allowing for efficient charging of power storage device 10B. On the other hand, if an abnormality or failure occurs in uninterruptible power supply 1B, it is possible to slowly charge power storage device 10B using uninterruptible backup power supply 1A, the backup device, making it possible to ensure discharge power from power storage device 10B in the event of a power outage. Furthermore, if uninterruptible backup power supply 1A fails, it is possible to slowly charge power storage device 10B using uninterruptible power supply 1B, the regular device, making it possible to ensure discharge power from power storage device 10B in the event of a power outage.

(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 the configuration of the uninterruptible power supply system.

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

In this example, we will explain the case where two uninterruptible power supplies 1C and 1D are installed, but this is not limited to two, and multiple uninterruptible power supplies may be installed in parallel.

The uninterruptible power supply 1C and the uninterruptible power supply 1D have basically 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.

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.

The power storage device 10D is provided in common with 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.

Uninterruptible power supply units 1C and 1D include a bypass circuit arranged in parallel with the power conversion circuit, which is made up of rectifiers 3C and 3D and inverters 4C and 4D, to ensure continuous UPS output to the load even if a failure occurs in the power conversion circuit.

Uninterruptible power supply 1C and uninterruptible power supply 1D have bypass-side switches 8C and 8D, each consisting of a thyristor and a contactor, and switching can be performed without interruption by turning on bypass-side switches 8C and 8D.

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 always 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 storage device 10D, which serves as the 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.

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

Control circuits 9C and 9D constantly exchange information regarding the inverter power supply signal, and also receive inputs of master unit setting signals and slave unit setting signals.

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.

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

In this state, power was also being supplied to the load, so the power storage device 10D was being charged at a low rate.

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

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.

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

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 the first voltage (> second voltage) and charges the power storage device 10D. This enables rapid charging of the power storage device 10D.

Meanwhile, the control circuit 9C receives the master unit setting signal and the master unit inverter setting signal. This causes the control circuit 9C to output a charging stop command to the chopper circuit 5C.

As another example, when the control circuit 9C receives a master device setting signal and no inverter setting signal is input from the slave device, the control circuit 9C 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 and charges the power storage device 10D.

As another example, the 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. 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.

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

Figure 8 is a diagram illustrating the charging state (part 1) of the uninterruptible power supply standby parallel system based on embodiment 2. As shown in Figure 8, 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 the first voltage (> second voltage) and charges the power storage device 10D. This enables rapid charging of the power storage device 10D.

Meanwhile, the control circuit 9C receives a master unit setting signal and also receives a master unit inverter setting signal. This causes the control circuit 9C to output a charge stop command to the chopper circuit 5C. A high-rate charge command is output to the chopper circuit 5D, causing rapid charging from the uninterruptible power supply 1D to the power storage device 10D. 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, allowing it to supply stable power to the load.

Figure 9 is a diagram illustrating the charging state (part 2) of the uninterruptible power supply standby parallel system based on embodiment 2. As shown in Figure 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, control circuit 9D may stop the inverter power supply signal from uninterruptible power supply 1D's control circuit 9D to uninterruptible power supply 1C's control circuit 9C.

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 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 charges the power storage device 10D. As a result, slow charging is performed on the power storage device 10D.

A low-rate charging command is output to the chopper circuit 5C, causing the uninterruptible power supply 1C to slowly charge the power storage device 10D.

Figure 10 is a diagram illustrating the charging state (part 3) of the uninterruptible power supply standby parallel system based on embodiment 2. As shown in Figure 10, if an abnormality occurs in uninterruptible power supply 1C, control circuit 9C switches the inverter power supply signal from the master inverter setting signal to the slave inverter setting signal. 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 control circuit 9D to output 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. This causes slow charging of power storage device 10D.

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.

The control circuit 9D determines that the uninterruptible power supply 1C has failed when the inverter power supply signal from the control circuit 9C is not input as an inverter power supply signal. This causes the control circuit 9D to output a low-rate charging command to the chopper circuit 5D. Based on the low-rate charging command, the chopper circuit 5D sets the DC voltage to the second voltage (< the first voltage) and charges the power storage device 10D. This causes the power storage device 10D to be slowly charged.

A low-rate charging command is output to the chopper circuit 5D, causing the uninterruptible power supply 1D to slowly charge the power storage device 10D.

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, allowing for efficient charging of power storage device 10D. On the other hand, if 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, making it possible to ensure discharge power from power storage device 10D in the event of a power outage. Alternatively, if 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, making it possible to ensure discharge power from power storage device 10D in the event of a power outage.

The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications that are equivalent in meaning to and within the scope of the claims.

1A Uninterruptible standby power supply, 1B, 1C, 1D Uninterruptible power supply, 3A, 3B, 3C, 3D Forward converter, 4A, 4B, 4C, 4D Inverse converter, 5A, 5B, 5C, 5D Chopper circuit, 7A, 7B, 7C, 7D DC input breaker, 8A, 8B, 8C, 8D Bypass switch, 9A, 9B, 9C, 9D Control circuit, 10B, 10D power storage device, 12B, 12D storage battery, 15A bypass input power supply, 16A, 16B, 16C, 16D commercial power supply.

Claims (4)

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. The uninterruptible power supply system of claim 1, wherein, when power is supplied to the AC load from the 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 slowly charged from the power conversion circuit of one of the first and second uninterruptible power supplies. an uninterruptible power supply for supplying 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 is
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;
a power storage device provided in common with the power conversion circuit and the standby power conversion circuit, the power storage device supplying power to the AC load when the AC power supply is powered down;
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. The uninterruptible power supply system according to claim 3, wherein when power is supplied from said power conversion circuit to said AC load, said first chopper circuit is set to a state in which charging of said power storage device is stopped .