JP2022121939A - Uninterruptible power supply system - Google Patents

Abstract

To provide an uninterruptible power supply system which uses a storage battery on a normal UPS side when a UPS is switched to a preparatory UPS.SOLUTION: A system comprises: a normal UPS 1B which supplies power to a load; and a preparatory UPS 1A which is used when the normal UPS fails. The normal UPS comprises: a power conversion circuit (a forward converter 3B, a backward converter 4B) which converts power from a commercial power supply 16B; and a bypass circuit 8B which supplies power from the preparatory UPS. The preparatory UPS comprises: a preparatory power conversion circuit (a forward converter 3A, a backward converter 4A) which converts power from a commercial power supply 16A; and a preparatory bypass circuit 8A which supplies power from a bypass input power supply 15A. The preparatory UPS further comprises: a first power storage device 10B which is connected with the power conversion circuit to supply power in power interruption of an AC power supply; a second power storage device 10A which is connected with the preparatory power conversion circuit to supply power in the power interruption of the AC power supply; and a switching circuit 1C which switches connection of the first power storage device to the preparatory power conversion circuit when the normal UPS fails.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an uninterruptible power supply system composed of a plurality of regular uninterruptible power supplies that constantly supply power to a load and a backup uninterruptible power supply configured as a backup in the event of a failure or inspection.

Conventionally, an uninterruptible power supply (hereinafter simply referred to as UPS) has been used as a power source for important loads such as computers, for which momentary power failure is not permitted.

Continuous power supply from a UPS power supply is required during normal operation and inspections 24 hours a day, 365 days a year.

Specifically, there are a plurality of regular UPSs that always supply power to the load, and a standby UPS that is configured to supply UPS power to the load even when the regular UPS fails or is inspected. A configured uninterruptible power supply system is provided (see Patent Document 1).

JP-A-2008-312371

On the other hand, if the normal UPS fails, it immediately switches to the standby UPS to continue supplying power, but when switching to the standby UPS, the storage battery provided on the normal UPS side is not used effectively. I have a problem.

An object of the present disclosure is to solve the above problems, and realize an uninterruptible power supply system that can efficiently use a storage battery provided on the normal UPS side when switching to a standby UPS. do.

According to one 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 if the uninterruptible power supply fails. The uninterruptible power supply includes a power conversion circuit that converts power from an AC power supply, and a first bypass circuit that is provided in parallel with the power conversion circuit and supplies power from the uninterruptible standby power supply. The uninterruptible standby power supply includes a standby power conversion circuit that converts power from an AC power supply, and a standby bypass circuit that is provided in parallel with the standby power conversion circuit and supplies power from a bypass input power supply. The uninterruptible power supply system is connected to a power conversion circuit and connected to a first power storage device that supplies power to an AC load in the event of a power failure of the AC power supply, and to a standby power conversion circuit that supplies power to the AC load in the event of a power failure of the AC power supply. A second power storage device for supplying power, and a switching circuit for switching connection between the first power storage device and the power conversion circuit to connection with the standby power conversion circuit when the uninterruptible power supply fails.

Preferably, the switching circuit includes a first switch section provided between the first power storage device and the power conversion circuit, and switching between the first power storage device and the standby power conversion circuit in parallel with the first switch section. and a second switch portion provided therebetween. Normally, the first switch section is set to the conducting state and the second switch section is set to the non-conducting state, and when the uninterruptible power supply fails, the first switch section is set to the non-conducting state and the second switch section section is set to a conductive state.

Preferably, the second switch section includes a backflow prevention diode.

Preferably, the second switch section includes a main switch and a sub-switch provided in parallel with the main switch. In the uninterruptible power supply system, when the uninterruptible power supply fails, one of the main switch and the sub-switch is set to a conductive state to supply power from the standby power conversion circuit to the first power storage device. and a charge control circuit for charging the

Preferably, the second switch section further includes a resistor. A resistor is connected in parallel with the main switch and in series with the sub-switch.

Preferably, the charge control circuit sets the conduction state of the main switch and the sub-switch based on the power storage states of the first and second power storage devices.

Preferably, the sub-switches correspond to semiconductor switches. The charge control circuit includes a gate control circuit that controls the gate of the semiconductor switch.

The uninterruptible power supply system of the present disclosure can efficiently use the storage battery provided on the normal UPS side when switching to the standby UPS.

It is a figure explaining circuit composition of an uninterruptible power supply system based on an embodiment. It is a figure explaining the circuit structure of the uninterruptible power supply system according to the modification 1 of embodiment. FIG. 4 is a diagram illustrating circuit configurations of a switch unit 31 and a charging control circuit 30 according to Modification 1 of the embodiment; FIG. 11 is a diagram illustrating circuit configurations of a switch unit 31# and a charge control circuit 30# according to a second modification of the embodiment; FIG. 10 is a diagram illustrating gate signals according to Modification 2 of the embodiment; FIG. 13 is a diagram illustrating circuit configurations of a switch unit 31#A and a charging control circuit 30# according to a modification 3 of the embodiment;

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

FIG. 1 is a diagram illustrating the circuit configuration of an uninterruptible power supply system according to an embodiment. As shown in FIG. 1, the uninterruptible power supply system includes an uninterruptible power supply 1B that supplies power to a load, an uninterruptible standby power supply 1A that is used when the uninterruptible power supply 1B fails, and an uninterruptible Power storage devices 10A and 10B, which are energy storage units, are provided corresponding to power failure standby power supply 1A and uninterruptible power supply 1B, respectively. The uninterruptible power supply system according to the embodiment also includes a switching circuit 1C that switches the supply path of the power storage device 10B. Details of the switching circuit 1C will be described later.

In this example, a case where an uninterruptible standby power supply 1A is provided as a backup of the uninterruptible power supply 1B will be described, but the uninterruptible standby power supply is not particularly limited to one, and an uninterruptible standby power supply for a plurality of uninterruptible power supplies It is good also as a structure which provides 1 A of apparatuses.

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

The uninterruptible standby power supply 1A and the uninterruptible power supply 1B include forward converters 3A and 3B that convert AC input to DC input, inverters 4A and 4B that convert DC input to AC input, and a DC input circuit breaker. 7A, 7B and control circuits 9A, 9B for controlling the inside thereof, respectively. It controls the operation of the power conversion circuit, switches, etc. according to instructions from the control circuits 9A and 9B.

The uninterruptible standby power supply 1A and the uninterruptible power supply 1B continue UPS output to the load even when a failure occurs in the power conversion circuit composed of the forward converters 3A and 3B and the inverters 4A and 4B. a bypass circuit provided in parallel with the power conversion circuit to obtain a

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

Uninterruptible power supply 1B receives AC input from commercial power supply 16B. The alternating current input is converted to direct current by the forward converter 3A and reversely converted back to alternating current by the inverse converter 4B. Inverter 4B always supplies a stable UPS output to the load. The DC input breaker 7B is connected in parallel with the forward converter 3A. When a power failure occurs in commercial power source 16B, DC energy of power storage device 10B, which is an energy storage unit, is supplied to inverter 4B via DC input breaker 7B. Thereby, the UPS output of the uninterruptible power supply 1B can be continuously supplied to the load.

Power to the bypass circuit of the uninterruptible power supply 1B is supplied from the uninterruptible standby 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 forward converter 3A and then reverse-converted to AC again by the inverter 4A so that a stable UPS output can always be supplied. A power storage device 10A, which is an energy storage unit, is connected in parallel with the forward converter 3A via a DC input breaker 7A. Further, the DC input circuit breaker 7A is connected in parallel with the power storage device 10A through the switching circuit 1C to the power storage device 10B.

A bypass circuit is provided in parallel with the commercial power supply 16A and supplies power with the bypass input power supply 15A as an input in order to obtain continuous UPS output even when a failure occurs in the forward converter 3A and the inverter 4A. be provided. The bypass circuit has a bypass side switch 8A consisting of a thyristor and a contactor, and switches without interruption by turning on the bypass side switch 8A. The bypass input power supply 15A is a commercial power supply like the normal AC input.

Power storage devices 10A and 10B include storage batteries 12A and 12B, switches 11A and 11B, and control units 13A and 13B that control power storage devices 10A and 10B.

Next, the configuration of the switching circuit 1C will be described.

Switching circuit 1C includes switches 21 and 23 and backflow prevention diode 22 .

Switch 23 is provided between DC input breaker 7B of uninterruptible power supply 1B and power storage device 10B. Switch 21 and backflow prevention diode 22 are connected in parallel with switch 23 and provided between DC input breaker 7A of uninterruptible standby power supply 1A and power storage device 10B.

Backflow prevention diode 22 is directly connected to switch 21 and cuts off power supply from uninterruptible standby power supply 1A to power storage device 10B. Backflow prevention diode 22 is provided to prevent overcurrent from flowing to power storage device 10B due to a voltage difference when the difference between the power storage capacity of power storage device 10A and the power storage capacity of power storage device 10B is large.

In the switching circuit 1C, the switch 21 is normally in a non-conducting state (OFF) and the switch 23 is in a conducting state (ON). Therefore, power storage device 10B and uninterruptible power supply 1B are electrically connected, and power storage device 10B and uninterruptible standby power supply 1A are electrically disconnected.

The uninterruptible power supply 1B normally turns on the DC input breaker 7B. The DC input converted by the forward converter 3A is supplied to the power storage device 10B via the DC input breaker 7B and the switch 23, and is ready to charge the storage battery 12B.

When a power failure occurs in commercial power supply 16B, DC energy of power storage device 10B is supplied to inverter 4B via DC input breaker 7B and switch 23 .

As described above, when a failure occurs in the power conversion circuit composed of the forward converter 3B and the inverter 4B of the uninterruptible power supply 1B, the operation of the power conversion circuit is stopped and the bypass side switch 8B is turned on. do. The uninterruptible standby power supply 1A supplies power to the load through the bypass circuit of the uninterruptible power supply 1B.

In the conventional configuration, since the power conversion circuit of the uninterruptible power supply 1B stops operating in this state, the power storage device connected to the power conversion circuit cannot be used effectively.

The switching circuit 1C of the uninterruptible power supply system according to the embodiment switches the connection between the power storage device 10B and the power conversion circuit of the uninterruptible power supply 1B to the power conversion of the uninterruptible standby power supply 1A when the uninterruptible power supply 1B fails. Switch to the connection with the circuit.

Specifically, the control circuit 9B of the uninterruptible power supply 1B causes the switching circuit 1C to output a switching command. Specifically, the switch 21 of the switching circuit 1C is set to a conducting state (ON), and the switch 23 is set to a non-conducting state (OFF). As a result, the connection between the power storage device 10B and the power conversion circuit of the uninterruptible power supply 1B is switched to the connection with the power conversion circuit of the uninterruptible standby power supply 1A.

Therefore, in the uninterruptible power supply system according to the embodiment, when a failure occurs in the power conversion circuit composed of the forward converter 3B and the inverter 4B of the uninterruptible power supply 1B, the power conversion of the uninterruptible standby power supply 1A Since the connection with the circuit can be switched, the power storage device 10B can be effectively used.

Specifically, when a power failure occurs in the commercial power supply 16A, the DC energy of the power storage device 10A is supplied to the inverter 4A via the DC input breaker 7A, and the DC energy of the power storage device 10B is supplied via the switch 21. is supplied to the inverter 4B.

Therefore, it is possible to ensure a long power supply compensation period during a power failure. In addition, since the power storage device 10B has a configuration that can be switched to be connected to the power conversion circuit of the uninterruptible standby power supply 1A, it is also possible to reduce the power storage capacity of the storage battery 12A of the power storage device 10A on the side of the uninterruptible standby power supply 1A. is. This can also reduce the cost of the uninterruptible power supply system.

Further, in this example, the control circuit 9B of the uninterruptible power supply 1B switches the switching circuit when a failure occurs in the power conversion circuit composed of the forward converter 3B and the inverter 4B of the uninterruptible power supply 1B. Although the case where the switching command is output to 1C has been described, the present invention is not limited to this. A command may be output.

(Modification 1)

FIG. 2 is a diagram illustrating a circuit configuration of an uninterruptible power supply system according to Modification 1 of the embodiment. As shown in FIG. 2, the uninterruptible power supply system differs from the uninterruptible power supply system described in FIG. 1 in that the switching circuit 1C is replaced with a switching circuit 1D.

The switching circuit 1C of the above-described embodiment has a configuration in which the backflow prevention diode 22 is provided to cut off the supply of electric power from the uninterruptible standby power supply 1A side to the power storage device 10B side. That is, it was the structure which could not charge from the uninterruptible standby power supply 1A side to the electrical storage apparatus 10B side.

The switching circuit 1D is configured to allow charging from the uninterruptible standby power supply 1A side to the power storage device 10B side.

The switching circuit 1D includes a charge control circuit 30, a switch section 31, a switch 23, and a voltage difference detection circuit .

Switch 23 is provided between DC input breaker 7B of uninterruptible power supply 1B and power storage device 10B. Switch unit 31 is connected in parallel with switch 23 and provided between DC input breaker 7A of uninterruptible standby power supply 1A and power storage device 10B. The voltage difference detection circuit 36 detects the difference between the voltage of the node on the power storage device 10B side and the voltage of the node on the power storage device 10A side. Voltage difference detection circuit 36 outputs the voltage difference to charging control circuit 30 .

Charging control circuit 30 receives a switching command input from control circuit 9B and a voltage difference input from voltage difference detection circuit 36 to control switch section 31 and switch 23 .

FIG. 3 is a diagram illustrating circuit configurations of switch unit 31 and charging control circuit 30 according to Modification 1 of the embodiment. As shown in FIG. 3, the switch section 31 includes a main switch 32, a sub-switch 33, and a resistor . A sub-switch 33 is connected in series with a resistor 34 . Sub switch 33 and resistor 34 are connected in parallel with main switch 32 . In this example, when the main switch 32 is on, the sub-switch 33 is off. On the other hand, when the sub-switch 33 is on, the main switch 32 is off.

Specifically, when the difference between the voltage at the node on the power storage device 10B side and the voltage at the node on the power storage device 10A side is large, the main switch 32 is turned off and the sub-switch 33 is turned on. In this case, a current path is formed through sub-switch 33 and resistor 34 . Therefore, even if the voltage difference is large, the amount of current can be suppressed because the resistor 34 is provided.

On the other hand, when the voltage difference is small, the main switch 32 is turned on and the sub-switch 33 is turned off. In this case, since the voltage difference is small, it is not necessary to suppress the amount of current.

Charging control circuit 30 includes an inverter 43 , a determination circuit 40 and AND circuits 41 and 42 .

As an example, the control circuit 9B of the uninterruptible power supply 1B, when a failure occurs in the power conversion circuit configured by the forward converter 3B and the inverter 4B of the uninterruptible power supply 1B, to the switching circuit 1D Outputs a switching command (“H” level).

Inverter 43 outputs “H” level to switch 23 when the switching command is at “L” level. In this case, switch 23 is turned on. On the other hand, inverter 43 outputs “L” level to switch 23 when the switching command is at “H” level. In this case, switch 23 is turned off.

The determination circuit 40 compares the voltage difference X with the reference value Y and outputs the comparison result. Specifically, when the voltage difference X is greater than the reference value Y, the comparison result (“H” level) is output. If the voltage difference X is equal to or less than the reference value Y, the determination circuit 40 outputs the comparison result (“L” level). The reference value Y can be set to any value.

The AND circuit 42 outputs to the sub-switch 33 the signal based on the comparison result of the determination circuit 40 and the AND logic operation result based on the switching command.

The AND circuit 41 outputs to the main switch 32 an AND logical operation result based on the inverted signal of the signal based on the comparison result of the determination circuit 40 and the switching command.

AND circuit 42 outputs "H" level based on the comparison result ("H" level) and the switching command ("H" level).

AND circuit 41 outputs "H" level based on the inverted signal of the comparison result ("L" level) and the switching command ("H" level).

Therefore, when the switching command (“H” level) is input and the voltage difference is large, the sub-switch 33 is turned on and the main switch 32 is turned off. When the switching command (“H” level) is input and the voltage difference is small, the sub-switch 33 is turned off and the main switch 32 is turned on.

With this configuration, the switching circuit 1D is configured to allow charging while suppressing excessive current from flowing from the uninterruptible standby power supply 1A side to the power storage device 10B side.

(Modification 2)

FIG. 4 is a diagram illustrating circuit configurations of switch unit 31# and charge control circuit 30# according to Modification 2 of the embodiment. As shown in FIG. 4, this example differs in that charge control circuit 30 is replaced with charge control circuit 30#.

Switch unit 31 # includes a main switch 32 and a semiconductor switch 35 . The semiconductor switch 35 has a gate and controls the voltage applied to the gate.

The semiconductor switch 35 is connected in parallel with the main switch 32 . In this example, the semiconductor switch 35 does not operate when the main switch 32 is on. On the other hand, when the semiconductor switch 35 is operating, the main switch 32 is off.

Specifically, when the difference between the voltage at the node on the power storage device 10B side and the voltage at the node on the power storage device 10A side is large, the main switch 32 is turned off and the semiconductor switch 35 operates. In this case, the semiconductor switch 35 performs switching operation. Therefore, even when the voltage difference is large, the semiconductor switch 35 performs switching operation, so that the amount of current can be suppressed.

On the other hand, when the voltage difference is small, the main switch 32 is turned on and the semiconductor switch 35 does not operate. In this case, since the voltage difference is small, it is not necessary to suppress the amount of current.

Charge control circuit 30 # further includes a pulse control circuit 51 and a triangular wave generation circuit 52 as compared with charge control circuit 30 .

AND circuit 42 outputs a signal for driving pulse control circuit 51 .

If the voltage difference X is greater than the reference value Y, the determination circuit 40 outputs the comparison result (“H” level).

Pulse control circuit 51 operates according to the output signal (“H” level) of AND circuit 42 . The output signal of AND circuit 42 ("L" level) does not operate.

A triangular wave generating circuit 52 generates a triangular wave. The pulse control circuit 51 outputs a gate signal for controlling the gate of the semiconductor switch 35 based on the triangular wave from the triangular wave generating circuit 52 and the voltage difference signal.

FIG. 5 is a diagram illustrating gate signals according to Modification 2 of the embodiment. As shown in FIG. 5, the pulse control circuit 51 outputs the gate signal based on the comparison between the voltage difference and the triangular wave. Specifically, when the voltage difference is larger than the triangular wave, an "L" level signal is output, and when the voltage difference is smaller than the triangular wave, an "H" level signal is output.

Therefore, pulse control circuit 51 outputs a pulse signal that repeats "H" level and "L" level. When the voltage difference is small, the period of the triangular wave above the voltage difference is long, so the period of the gate signal (“H” level) is long. On the other hand, when the voltage difference is large, the period of the triangular wave above the voltage difference becomes short, so the period of the gate signal (“H” level) becomes short. That is, it is possible to adjust the ON/OFF period of the gate of the semiconductor switch 35, and to efficiently suppress the amount of current.

(Modification 3)

FIG. 6 is a diagram illustrating circuit configurations of switch unit 31#A and charge control circuit 30# according to Modification 3 of the embodiment. As shown in FIG. 6, it differs from the configuration of FIG. 4 in that switch section 31# is replaced with switch section 31#A. The switch section 31#A differs in that a resistor 34 is further provided. Specifically, the semiconductor switch 35 and the resistor 34 are connected in series. A semiconductor switch 35 and a resistor 34 are connected in parallel with the main switch 32 .

With this configuration, when the semiconductor switch 35 is turned on, the amount of current can be further suppressed because the resistor 34 is provided.

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

1A uninterruptible standby power supply, 1B uninterruptible power supply, 1C, 1D switching circuit, 3A, 3B forward converter, 4A, 4B reverse converter, 7A, 7B DC input breaker, 8A, 8B bypass side switch, 9A, 9B control circuit 10A, 10B power storage device 12A, 12B storage battery 13A, 13B control unit 15A bypass input power supply 16A, 16B commercial power supply 22 backflow prevention diode 30, 30# charge control circuit 32 main switch 33 Sub switch, 34 resistor, 35 semiconductor switch, 36 voltage difference detection circuit, 40 determination circuit, 41, 42 AND circuit, 43 inverter, 51 pulse control circuit, 52 triangular wave generation circuit.

Claims (7)

an uninterruptible power supply that supplies power to an AC load;
An uninterruptible standby power supply that is used when the uninterruptible power supply fails,
The uninterruptible power supply,
a power conversion circuit that converts power from an AC power supply;
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,
a standby power conversion circuit that converts power from the AC power supply;
a backup bypass circuit that is provided in parallel with the backup power conversion circuit and supplies power from a bypass input power supply;
a first power storage device connected to the power conversion circuit and supplying power to the AC load when the AC power supply fails;
a second power storage device connected to the standby power conversion circuit and supplying power to the AC load when the AC power supply fails;
The uninterruptible power supply system further comprising a switching circuit that switches connection between the first power storage device and the power conversion circuit to connection with the standby power conversion circuit when the uninterruptible power supply fails. The switching circuit is
a first switch unit provided between the first power storage device and the power conversion circuit;
a second switch unit provided between the first power storage device and the standby power conversion circuit in parallel with the first switch unit;
In a normal state, the first switch section is set to a conducting state and the second switch section is set to a non-conducting state,
2. The uninterruptible power supply system according to claim 1, wherein said first switch section is set in a non-conducting state and said second switch section is set in a conducting state when said uninterruptible power supply fails. 3. The uninterruptible power supply system according to claim 2, wherein said second switch section includes a backflow prevention diode. The second switch section
main switch and
a sub-switch provided in parallel with the main switch,
When the uninterruptible power supply fails, one of the main switch and the sub-switch is set to a conductive state to supply power from the standby power conversion circuit to restore the first power storage device. 3. The uninterruptible power system of claim 2, further comprising a charge control circuit for charging. The second switch section further includes a resistor,
5. The uninterruptible power system of claim 4, wherein the resistor is connected in parallel with the main switch and in series with the sub-switch. 5. The uninterruptible power supply system according to claim 4, wherein said charging control circuit sets the conductive state of said main switch and said sub-switch based on the power storage states of said first and second power storage devices. The sub-switch corresponds to a semiconductor switch,
The uninterruptible power supply system according to any one of claims 4 to 6, wherein said charge control circuit includes a gate control circuit that controls a gate of said semiconductor switch.

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