JP2002218673A - Uninterruptible power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power unit having small power loss during normal operation. SOLUTION: The uninterruptible power supply is provided with a bypass circuit 21 whose one end is connected to an input side of a converter 12 to bypass circuits of a converter 12 and an inverter 13, an uninterruptible electric switch 14 connected to the other end of the bypass circuit 21 and the AC output side of the inverter 13, a control circuit for uninterruptible function in which the output of the inverter 13 is used as power always supplied to load and the power is switched to the bypass circuit 21 to operate in case of failure and inspection of circuits in the converter 12 and the inverter 13, and a selecting switch 23 which switches and selects the control circuit for uninterruptible function and a control circuit for backup function in which continuously supplied power is immediately switched to the output from the inverter 13 to operate by the bypass circuit 21 in the event of a power failure in a commercial ac power 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter, an inverter, and a bypass circuit for bypassing the converter and an inverter. The converter is connected to a commercial AC power supply. The present invention relates to an uninterruptible power supply which supplies power to a load by converting the power to a load and supplies power to the load by a bypass circuit in the case of failure or inspection of a converter or an inverter.

[0002]

2. Description of the Related Art Uninterruptible power supplies (UPS) have been widely used as power supplies for important loads such as computers, for example, in which instantaneous power failure is not allowed. FIG.
1 is a block diagram illustrating a basic configuration example of a general uninterruptible power supply 1 of this type. That is, in FIG. 4, the AC input 2 input from the commercial power supply is input to the converter 12 via the AC input circuit breaker 11 of the uninterruptible power supply 1 and converted into DC, and further converted back to AC by the inverter 13. The AC output 3 that is converted and obtained through the non-interruptible switching circuit 14 is supplied to the load 4. On the other hand, the output of converter 12 is stored as DC energy in storage battery 16 as an energy storage unit via DC input circuit breaker 15.

When a power failure occurs in the AC input 2, the power failure detector 17 detects the power failure and stops the converter 12 by the converter control circuit 18A. DC energy of the storage battery 16 is supplied to the inverter 13, and the power of the UPS 1 The AC output 3 is continuously supplied to the load 4 without interruption.

[0004] There is a slight voltage difference between the DC voltage at the output of the converter 12 operating using the normal AC input 2 as a power supply and the DC voltage supplied from the DC energy of the storage battery 16 when the AC input 2 fails. From the inverter control circuit
19A controls the output voltage of the inverter 13 to be always constant.

If a fault occurs in the inverter 13, for example, the thyristor switch 14B on the bypass circuit 21 side is turned on by the non-instantaneous interruption switching control circuit 20A, and the thyristor switch 14A on the inverter 13 side is turned off. Switching to power supply by the bypass circuit 21 is performed. Reference numeral 22 denotes a bypass breaker.

[0006] The configuration and operation of the conventional uninterruptible power supply are as described above. However, since the conventional uninterruptible power supply is composed of many devices such as converters and inverters, a large number of devices are required during operation. Loss occurs. The value depends on the capacity of the uninterruptible power supply, for example, 100 kVA.
In the case of uninterruptible power supply of medium capacity, it is quite large, about 10%.

[0007]

The most important task of an uninterruptible power supply is to provide a continuous and stable power supply to a load even when a commercial power supply fluctuates or a power outage occurs. The device has the above configuration and operation. Therefore, a loss at the time of operation also occurs as described above.

[0008] Electronic equipment such as a computer is required to supply power with high precision, and of course, is not allowed to have any momentary interruption. Therefore, it is essential to supply power using an uninterruptible power supply. However, when the load is a rotating machine such as a motor, there is inertia, so that a certain fluctuation of the power supply and a momentary interruption of about サ イ ク ル cycle generally do not pose a problem.

For this reason, recently, when it is desired to continue supplying power to such a load even when the commercial power supply is interrupted, a backup power supply (SPS) of a continuous commercial power supply operation type has been used. FIG. 5 is a block diagram showing a basic configuration example of a general backup power supply device 5 of this type.

In FIG. 5, an AC input 2 input from a commercial power supply is normally supplied to a load 4 by an AC output 3 by a bypass circuit 21 via a bypass breaker 22. The converter 12 performs charging to supplement self-discharge of the storage battery 16 used as a DC energy source when the AC input 2 fails.

If a power failure occurs in the AC input 2, the power failure detector 17 detects this, and the converter control circuit 18B stops the converter 12, and the inverter control circuit 19
The inverter 13 is started by B. In addition, in order to switch the output to the AC output 3 from the bypass circuit 21 to the output from the inverter 13, the thyristor switch 14A connected to the inverter 13 is turned off by the instantaneous interruption switching control circuit 20B.
N, the thyristor switch 14B on the bypass side is turned off.

At the time of the power failure of the AC input 2, the inverter 13 is activated to switch to the power supply on the converter side, so that the switching to the inverter 13 is momentarily interrupted for about 1/2 cycle.

However, even if the switching to the inverter 13 is momentarily interrupted, the power supply to the AC
Can be supplied and the AC input 2 of the commercial power supply is always supplied to the load 4 as the AC output 3 as it is, so that the loss during operation becomes very small. For this reason, the backup power supply device is often used when the load is a rotating machine such as a motor, which does not cause any problem even if the power supply fluctuates or an instantaneous interruption of about サ イ ク ル cycle occurs.

As described above, the uninterruptible power supply and the backup power supply are power supplies for backing up the same AC input power failure, but suitable loads are different like a computer and a motor.

[0015] For this reason, for example, an uninterruptible power supply was first introduced and operated because the load was a computer, but then the load was changed to a motor and operation as a backup power supply was sufficient. In the past, it is necessary to newly install a backup power supply device, and equipment cost is required. Therefore, it is an object of the present invention to provide an uninterruptible power supply that can be applied to any load and has low power loss during normal operation.

[0016]

In order to achieve the above object, an uninterruptible power supply according to the present invention comprises: a converter for converting AC input from a commercial AC power supply into DC; a DC output of the converter; An inverter for converting the output into an alternating current; a bypass circuit having one end connected to the input side of the converter and provided to bypass the converter and the circuit of the inverter; and the other end of the bypass circuit and the AC output of the inverter. The non-instantaneous interruption switching circuit connected to the power supply side and the power that is always supplied to the load are output from the inverter, and the switching operation is switched to the supply from the bypass circuit in the case of failure or inspection of the converter and the inverter circuit. The control circuit for the power failure function and the power that is always supplied to the load are stopped by the bypass circuit to the commercial AC power supply. A control circuit for a backup function that instantaneously switches to the output from the inverter when an error occurs, a control circuit for the backup function, and a selection switch for switching and selecting the control circuit for the uninterruptible function. The configuration is provided with.

The uninterruptible power supply of the present invention can always supply a stable power supply from the inverter when the load is a computer and, when the load is a motor, use a power supply with a small operating loss during normal operation. Can be supplied.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. That is, as shown in FIG. 1, the uninterruptible power supply 6 of the present embodiment includes a converter 12 for converting AC power of a commercial frequency supplied from the AC input 2 to DC, and a DC power output from the converter 12. An inverter 13 for converting into an alternating current having a predetermined frequency and a predetermined voltage;
Instantaneous interruption switching circuit 14 connected to the output side of this inverter
And A storage battery 16 is externally connected between the converter 12 and the inverter 13.

The instantaneous interruption switching circuit 14 is a thyristor switch 14
A and 14B, and the input side of the thyristor switch 14A is connected to the input point of the AC input 2 by a bypass circuit 21. A power failure detector 17 is connected to the input point of the AC input 2, and the output side of the power failure detector 17 is connected to the input side of the uninterruptible function / backup function selection switch 23.

On the output side of the uninterruptible power / backup function selecting switch 23, converter control circuits 18A and 18B for controlling the converter 12, inverter control circuits 19A and 19B for controlling the inverter 13, and an instantaneous interruption switching circuit 14 Instantaneous interruption switching control circuits 20A and 20B for controlling the power supply.

In the uninterruptible power supply of this embodiment having such a configuration, when the uninterruptible function / backup function selecting switch 23 is set to the uninterruptible function side, the converter control circuit 18A and the inverter control circuit 19A. And the instantaneous interruption switch control circuit 20A operates.

At this time, the uninterruptible power supply operates according to the flow of FIG. That is, the power failure detector 17 detects a decrease in the AC input voltage (step SU1).
Then, the converter control circuit 18A operates via the uninterruptible function / backup function selection switch 23 to stop the converter 12 (step SU2). The power failure is displayed in response to the stop of the converter 12 (step SU3). However, the inverter 13 receives the control signal from the inverter control circuit 19A and continues the operation with the power supply of the storage battery 16 input (step S3).
U4). Although the voltage of the storage battery 16 gradually decreases as the operation is continued, it is determined in step SU5 whether the storage battery voltage is not lower than the specified value. If No, the power supply to the load 4 is continued (step SU6). Ye
In the case of s, the device is stopped (step SU7).

In the uninterruptible power supply of the present embodiment, when the uninterruptible function / backup function selection switch 23 is selected to the backup function side, the converter control circuit 18B, the inverter control circuit 19B and the uninterruptible power supply switching are performed. The control circuit 20B operates.

In this case, the uninterruptible power supply operates according to the flow shown in FIG. That is, the power failure detector 17 detects a drop in the AC input voltage (step SS).
1) and uninterruptible function / backup function selection switch 23
The inverter control circuit 19B operates via the
Is started (step SS2). When the output voltage of the inverter 13 is established (step SS3), the instantaneous interruption switching circuit
When the power is supplied to the load 4 by the control signal from the battery 20B, the voltage of the storage battery 16 decreases. In step SS5, it is determined whether the voltage is equal to or less than a specified value. If No, the load power supply is continued (step SS6). If yes, stop the device (step SS7).

[0025]

As described above, the uninterruptible power supply according to the present invention has both an uninterruptible function capable of always supplying stable power and a backup function with a small operating loss and can be switched and selected. Thus, even if the load is changed from a computer to a motor or vice versa as in the prior art, it is not necessary to newly install a backup power supply or an uninterruptible power supply, and the equipment cost can be reduced. In addition, the uninterruptible power supply function provides a high-performance power supply without instantaneous interruption, and the backup function reduces power loss during normal operation. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an uninterruptible power supply according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of an uninterruptible power supply function of the uninterruptible power supply according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of a backup function of the uninterruptible power supply according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional uninterruptible power supply.

FIG. 5 is a block diagram showing a configuration of a conventional backup power supply device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Uninterruptible power supply (conventional), 2 ... AC input, 3 ... AC output, 4 ... Load, 5 ... Backup power supply, 6 ... Uninterruptible power supply (this invention), 11 ... AC input breaker, 12 ... Converter, 13… Inverter, 14… Instantaneous interruption switching circuit, 14A,
14B: Thyristor switch, 15: DC input circuit breaker, 16:
Storage battery, 17: Power failure detector, 18A, 18B: Converter control circuit, 19A, 19B: Inverter control circuit, 20A, 20B ...
Instantaneous interruption switching control circuit, 21: bypass circuit, 22: bypass circuit breaker, 23: uninterruptible function / backup function selection switch.

Claims (1)

[Claims] 1. A converter for converting AC input from a commercial AC power supply to DC, an inverter for converting DC output of the converter and DC output of a storage battery to AC,
A bypass circuit having one end connected to the input side of the converter and bypassing the circuit of the converter and the inverter, and a momentary interruption switching connected to the other end of the bypass circuit and the AC output side of the inverter; A circuit and a control circuit for an uninterruptible power supply function that always supplies power to the load as an output of the inverter, and switches to power supply from the bypass circuit in the case of failure or inspection of the converter and the inverter circuit. A control circuit for a backup function that instantaneously switches to an output from the inverter when a power failure occurs in the commercial AC power supply by the bypass circuit, and a control circuit for the backup function. Circuit and a selection switch for switching and selecting a control circuit for the uninterruptible function. Uninterruptible power supply and butterflies.