JPH04322138A - Ac power supply system - Google Patents

Abstract

PURPOSE:To enhance reliability of an AC power supply system for feeding a load with power from a stand-by power supply upon interruption of commercial power supply. CONSTITUTION:A power interruption detection signal 51 representing the power supply state of a commercial power supply 1 is fed from a commercial power supply detecting circuit 5 to a power supply system switching unit 3 as well as to a controller 4 performing start/stop control of stand-by power supply 2 and switching the power supply system based on a stand-by power supply signal 41. The power supply system switching unit 3 controls a switch 33 based on a logical product of the power interruption detection signal 51 and the stand-by power supply signal 41 fed from the controller 4 thus switching the power supply system for a laid 7. According to the system, erroneous switching to the stand-by power supply 2 is prevented resulting in enhancement of reliability in AC power supply to the load 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC power supply system used as a power system for building facilities, communication equipment, etc.

0002

2. Description of the Related Art An example of the configuration of this type of AC power supply system is a conventional example shown in FIG. First, in the configuration of this conventional example, the commercial power supply 1 is connected to the power supply system switching device 3 via the commercial power supply detection circuit 5, and the standby power supply 2 is connected to the power supply system switching device 3 via the standby power supply detection circuit 6. AC power from the commercial power supply 1 or the standby power supply 2 is connected to the AC load 7 via the changeover switch 33 of the power supply system switching device 3 . The power supply system switching device 3 is connected to a control device 4 , and the changeover switch 33 is controlled by output signal pulses 42 and 43 of the control device 4 . The control device 4 includes a start/stop signal generation circuit 44, a switching signal generation circuit 45, and a control processor 46, and performs start/stop control of the backup power source 2 and switching control of the power supply system switching device 3. There is. A power outage detection signal 51 is input from the commercial power supply detection circuit 5 to the start/stop signal generation circuit 44 and the switching signal generation circuit 45, and a power supply start signal 61 is input from the standby power supply detection circuit 6 to the switching signal generation circuit 45. It has been entered. Based on these input signals 51 and 61, the start/stop signal generation circuit 44 outputs the start signal pulse 22 or the stop signal pulse 23 to the backup power supply 2, and the switching signal generation circuit 45 outputs the start signal pulse 22 or stop signal pulse 23 to the backup power supply 2 side. Switching signal pulse 42 or switching signal pulse 4 to the commercial power supply 1 side
3 is output to the power supply system switching device 3.

FIG. 4 is a diagram showing the operating states and signal waveforms of each part in such a conventional example. In addition, when the power failure detection signal 51 is at a high level (H), it indicates a power failure state of the commercial power supply 1.
It is assumed that the low level (L) represents the normal state of the commercial power supply 1. In addition, the power supply start signal 61 is at a low level (L
) indicates the standby power supply 2 is in a stopped state, and the high level (H
) represents a state in which the backup power source 2 can supply power. The operation of the conventional example will be explained as follows with reference to FIG.

[0004] Power is normally supplied from the commercial power supply 1 to the AC load 7 via the power supply system switching device 3 . When the commercial power supply 1 stops and the commercial power supply detection circuit 5 detects a power outage, the power outage stop signal 51 is changed from low level (L) to high level (H). The control device 4 confirms the power outage of the commercial power source 1, immediately sends a start signal pulse 22 to the backup power source 2, and receives a power supply start signal 61 from the backup power source detection circuit 6.
After waiting for the voltage to change from low level (L) to high level (H) and confirming that the backup power source 2 can supply power, the switching signal pulse 42 to the backup power source 2 side is sent to the selector switch 33. do. After receiving the switching signal pulse 42 to the backup power source 2 side, the power system switching device 3 switches the changeover switch 33 from the commercial power source 1 side to the backup power source 2 side, thereby continuing to supply power to the AC load 7 during a power outage. I'm letting you do it.

Next, when the commercial power supply 1 is restored, the commercial power supply detection circuit 3 detects the power restoration and changes the power failure detection signal 51 from high level (H) to low level (L). The control device 4 confirms the restoration of the commercial power source 1 and immediately sends a switching signal pulse 43 to the commercial power source 1 side to the changeover switch 33. After receiving the switching signal pulse 43 to the commercial power source 1 side, the changeover switch 33 switches the power supply system from the standby power source 2 side to the commercial power source 1 side. After this, the control device 4
A stop signal pulse 23 is sent out, and in response to this, the backup power source 2 stops operation.

[0006]

[Problems to be Solved by the Invention] However, in the above conventional AC power supply system, the commercial power supply 1
Only the control device 4 determines whether or not the standby power source 2 is in a normal state and whether or not the backup power source 2 is in a state where power can be supplied. Therefore, even though the commercial power source 1 is normal and power cannot be supplied from the backup power source 2, the switching signal pulse 42 to the backup power source 2 side is sent to the power supply system switching device 3 due to a malfunction of the circuit in the control device 4. When the power is sent out, there is a problem in that the power supply system is switched to the standby power supply 2 side, and there is a possibility that the power supply to the AC load 7 will be stopped. This problem results in lower reliability of power supply because the control device 4 becomes a common part of the AC power supply system. Therefore, in order to increase the reliability of power supply, it is essential to improve the reliability of the control device 4, which has been a problem that increases the cost of the device.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide highly reliable AC power that switches the power supply system to a standby power source only in the event of a power outage of the commercial power source, without causing an increase in cost. The goal is to provide a supply system.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the AC power supply system of the present invention includes a commercial power source, a commercial power detection circuit for detecting whether the commercial power source is normal or a power outage, and a backup power source. a power supply, a standby power detection circuit that detects whether the standby power supply is capable of supplying power or is stopped, and a power supply system switching device that uses the commercial power supply and the standby power supply as a power supply system, switches the power supply system, and supplies power to a load. and a control device that performs start-up/stop control of the backup power source based on detection signals from the commercial power supply detection circuit and the backup power supply detection circuit, and instructs switching of the power supply system switching device. In AC power supply system,
The supply system switching device includes a circuit that takes a logical product of the detection signal of the commercial power supply detection circuit and a signal from the control device instructing switching to a backup power source, and the power supply system switching device performs the logical product The present invention is characterized in that the power supply system is switched by.

[0009]

[Operation] In the AC power supply system of the present invention, a detection signal indicating the power supply status of the commercial power supply is inputted not only to the control device that instructs switching of the power supply system but also to the power supply system switching device, and in the power supply system switching device, The power supply system is switched by performing a logical product with a signal from the control device that instructs switching. This prevents a malfunction of the control device from switching to a stopped standby power source even though the commercial power source is normal, thereby increasing the reliability of AC power supply to the load.

0010

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. As the constituent parts of this embodiment, 1 in the figure is a commercial power source which is an AC power source, 2 is a backup power source, 3 is a power supply system switching device,
4 is a control device, 5 is a detection circuit for commercial power supply, 6 is a detection circuit for backup power supply, and 7 is an AC load. Further, as parts constituting the power supply system switching device 3, 32 indicates an AND circuit, 33 indicates a changeover switch, and as components constituting the control device 4, 40 indicates a buffer circuit, and 46 indicates a control processor. Furthermore, as input/output signals between each part, 21 represents a start signal, 31 a switching signal, 41 a standby power supply signal, 51 a power failure detection signal, and 61 a power supply start signal.

The above-mentioned parts are connected as follows. The commercial power supply 1 is connected to the power supply system switching device 3 via the commercial power supply detection circuit 5, the backup power supply 2 is connected to the power supply system switching device 3 through the backup power supply detection circuit 6, and the commercial power supply 1
Alternatively, AC power from the backup power supply 2 is supplied to the power supply system switching device 3.
It is connected to the AC load 7 via the changeover switch 33 . The control device 4 receives a power failure detection signal 51 from the commercial power supply detection circuit 5 and a power supply start signal 6 from the standby power supply detection circuit 6.
1 is input respectively. Further, the control device 4 outputs the activation signal 21 to the backup power supply 2 and outputs the backup power supply feed signal 41 to the AND circuit 32 of the power supply system switching device 3. These input/output signals 41, 51, 61 in the control device 4 are input/output via the buffer circuit 40. In the power supply system switching device 3, the AND circuit 32 receives the power failure detection signal 51 from the commercial power supply detection circuit 5 and the above-mentioned standby power supply signal 41 from the control device 4, and the AND circuit 32 receives the above-mentioned backup power supply signal 41 from the control device 4. A switching signal 31 is generated from two input signals, that is, a standby power supply signal 41 and a power outage detection signal 51, and is output to the changeover switch 33.

The operation and effects of one embodiment constructed as described above will be described with reference to FIG. 2, which shows the operating states and signal waveforms of each part of this embodiment. It is assumed that the power failure detection signal 51 represents a power outage state of the commercial power supply 1 when it is at a high level (H), and represents a normal state of the commercial power supply 1 when it is at a low level (L). Furthermore, when the power supply start signal 61 is at a low level (L), it indicates a stopped state of the backup power source 2, and when it is at a high level (H), it indicates a state where the backup power source 2 is ready to supply power. Further, when the standby power supply signal 41 is at a low level (L), it indicates that the standby power supply 2 is in a stopped state, and when it is at a high level (H), it indicates that the standby power supply 2 is in a state where power can be supplied. Furthermore, when the activation signal 21 is at a low level (L), it represents a stopped state of the backup power source 2, and when it is at a high level (H), it represents an activated state of the backup power source 2. Further, when the switching signal 31 is at a low level (L), the changeover switch 33 is connected to the commercial power supply 1 side, and when the changeover signal 31 is at a high level (H), the changeover switch 33 is connected to the standby power supply 2 side.

First, the operation during a power outage of the commercial power supply 1 will be described. Normally, power is supplied from the commercial power supply 1 to the AC load 7 via the power supply system switching device 3 . Here, commercial power supply 1
When the commercial power supply detection circuit 5 detects a power outage,
The power failure detection signal 51 is changed from low level (L) to high level (H). As a result, the control device 4 confirms the power outage of the commercial power supply 1 and immediately sends a start signal 2 to the standby power supply 2.
1 from low level (L) to high level (H). Next, the control device 4 waits for the standby power supply 2 to start up and for the power supply start signal 61 from the standby power supply detection circuit 6 to change from low level (L) to high level (H), and then After confirming that the backup power source 2 can supply power, the backup power supply signal 41 is changed from low level (L) to high level (H). The AND circuit 32 outputs the logical product of the backup power supply signal 41 and the power outage detection signal 51 to the changeover switch 33 as the switching signal 31 . That is, when both the standby power supply signal 41 and the power outage detection signal 51 are at a high level (H), the switching signal 31 is at a high level (H). After receiving this high level (H) switching signal 31, the changeover switch 33 is switched from the commercial power supply 1 side to the backup power supply 2 side, and power supply to the AC load 7 is continued even during a power outage.

Next, the operation when the commercial power supply 1 recovers from a power outage will be described. When the commercial power supply 1 is restored, the commercial power supply detection circuit 5 detects the power restoration, and the power outage detection signal 51 is changed from high level (H) to low level (L). As a result, the logical product of the backup power supply signal 41 and the power failure detection signal 51 in the logical product circuit 32 becomes low level (L).
Changes to That is, the switching signal 31 is at a high level (
H) to low level (L), the selector switch 33 switches the power supply system from the backup power source 2 side to the commercial power source 1 side. The activation signal 21 changes from high level (H) to low level (L) when the commercial power supply 1 is restored, so the standby power supply 2 stops operating.

As described above, in this embodiment, the power failure detection signal 51 representing the power supply status of the commercial power supply 1 is inputted not only to the control device 4 but also to the AND circuit 32 of the power supply system switching device 3, and this AND is performed. The circuit 32 performs an AND operation between the power failure detection signal 51 and the standby power supply signal 41 that instructs switching from the control device 4, and uses this as the switching signal 31 to control the changeover switch 33. Therefore, the switching signal 31 changes from low level (L) to high level (H) only when the commercial power supply 1 is stopped and the standby power supply 2 is capable of supplying power.
), the changeover switch 33 is switched from the commercial power source 1 side to the backup power source 2 side, so even though the commercial power source 1 is normal, the power supply system is switched to the backup power source 2 side, and the power supply to the AC load 7 is interrupted. There is no fear that it will stop. Therefore, highly reliable power can be supplied to the AC load 7.

[0017]

Effects of the Invention As is clear from the above explanation, the AC power supply system of the present invention has a backup power source that is not in a state where power can be supplied even though the commercial power source is normal due to a malfunction in the circuit of the control device. Since there is no risk of switching the power supply system to the other side, highly reliable AC power can be supplied, and this has the advantage that it can be suitably applied to applications such as communication power supply systems that particularly require high reliability.

[Brief explanation of drawings]

[Fig. 1] A configuration diagram showing an embodiment of the present invention.

[Fig. 2] A diagram showing the operating states and signal waveforms of each part of the above embodiment.

[Figure 3] Configuration diagram showing a conventional example

[Fig. 4] A diagram showing the operating states and signal waveforms of each part of the above conventional example.

[Explanation of symbols]

1...Commercial power supply, 2...Backup power supply, 3...Power supply system switching device,
4... Control device, 5... Detection circuit for commercial power supply, 6... Detection circuit for standby power supply, 7... AC load, 21... Start signal, 31... Switching signal, 32... AND circuit, 33... Changeover switch, 40
...Buffer circuit, 41... Reserve power supply signal, 46... Control processor, 51... Power failure detection signal, 61... Power supply start signal.

Claims (1)

[Claims] Claim 1: A commercial power source, a commercial power source detection circuit that detects whether the commercial power source is normal or a power outage, a backup power source, and a backup power source detection circuit that detects whether the backup power source is capable of supplying power or is stopped. , a power supply system switching device that uses the commercial power supply and the backup power supply as a power supply system and switches the power supply system to supply power to the load, based on each detection signal of the commercial power supply detection circuit and the backup power supply detection circuit. In an AC power supply system comprising a control device that performs start-up/stop control of the backup power source and instructs switching of the power supply system switching device, the supply system switching device is provided with a detection signal of the commercial power supply detection circuit. and a signal from the control device instructing switching to a standby power source, the power supply system switching device switching the power supply system based on the logical product. system.