JP2793264B2 - Uninterruptible power system - Google Patents

Description

The present invention relates to an uninterruptible power supply for supplying stabilized power to a load, and in particular, when a failure occurs, the failure is transient. The present invention relates to an uninterruptible power supply having a function of determining whether a failure is a permanent failure or a permanent failure and shortening a failure recovery time.

(Prior art) The uninterruptible power supply is also introduced in Toshiba Review Vol. 42, No. 11 (November, 1987) PP877-880, etc., and its function and operation outline are known. With reference to FIG. 4, the following description will focus on the output voltage control method of the uninterruptible power supply and the problems of the related art.

In FIG. 4, 11 is an input AC power supply, 12 is a rectifier, 13
Is the inverter, 14 is the inverter transformer, 15 is the output terminal of the uninterruptible power supply, 16 is the battery, 17 is the switch, 18 is DC
Filter capacitor, 19 is AC filter capacitor, 20 is voltage reference setter, 21 is output voltage detection circuit, 22 is voltage controller, 23 is frequency controller, 24 is PWM controller, 25 is gate amplifier, and 26 is control A circuit power supply, 27 is an operation stop circuit, 28 is an operation stop command, and 29 is a failure detection circuit. 30 is a fuse, 31 is a circuit component provided for further protection.
Is a shunt, 32 is an input voltage detector, 33 is a DC voltage detector,
34 is a fuse blown detector, 35 is a DC overcurrent detector, 36 is an inverter overcurrent detector, 37 is an output overcurrent detector, 38 is an output overvoltage detector, 39 is a battery voltage detector, and 40 is a control power supply. It is a loss detector.

With the configuration of the uninterruptible power supply shown in this figure,
When 11 is normal, this is converted to DC power by the rectifier 12,
The power is smoothed by the DC filter capacitor 18, converted into AC power by the inverter 13, and supplied to the output terminal 15 through the inverter transformer 14 and the AC filter capacitor 19. The voltage of the output AC power is compared and controlled by the voltage controller 22 with the voltage reference Vr and the detection signal of the output voltage detection circuit 21, and the output signal is combined with the output signal of the frequency controller 23 and the PWM controller 24. The main circuit elements of the inverter 13 are controlled by PWM control via the gate amplifier 25. The output voltage is determined by the voltage reference 20, and the output frequency is determined by the frequency controller 23.

On the other hand, if the voltage of the input AC power supply 11 drops to, for example, 10% or less of the steady value due to a lightning strike or a ground fault, the power supply from the input AC power supply 11 cannot be continued. Upon detecting this, the switch 17 is turned on, and DC power is supplied from the battery 16 via the switch 17. In this way, when the voltage of the input AC power supply 11 drops, the power is supplied from the battery 16 so that the inverter 13
In addition, predetermined stabilized AC power can be output to the output terminal 15 via the inverter transformer 14. Generally, the battery 16 can compensate for such a power failure for about 5 to 10 minutes.

In order to monitor and protect the operation of the uninterruptible power supply functioning as described above, the operation stop circuit 27 operates as the uninterruptible power supply in accordance with the instruction of the operation stop instruction 28, and also operates the protection instruction in the failure detection circuit 29. To stop the operation. The failure detection circuit 29 is governed by a detection signal detected by a protection detector of each unit in the uninterruptible power supply. One example of these protection detectors is shown in FIG. An input voltage detector 32 for detecting overvoltage or undervoltage of the input AC power supply 11, a DC voltage detector 33 for detecting overvoltage or undervoltage of the output voltage of the rectifier 12, a shunt 31 for input overcurrent detection of the inverter 13; A DC overcurrent detector 35, a fuse 30 and a fuse blown detector 34 for protecting the DC overcurrent, an inverter overcurrent detector 36 for detecting the output overcurrent of the inverter 13, and an overvoltage of the voltage output from the output terminal 15. A protection detector for the main circuit, such as an output overvoltage detector 38 for detecting, an output overcurrent detector 37 for detecting and protecting the output overcurrent, a battery voltage detector 39 for detecting a voltage drop of the battery 16, and a control circuit power supply 26. There is a protection detector such as a control power loss detector 40 for detecting a power loss of the power supply. When the above-described protection detector detects protection, outputs a detection signal and gives a signal to the failure detection circuit 29, the operation command 28
The operation of the uninterruptible power supply was finally stopped irrespective of the state.

An example of a power supply system using such an uninterruptible power supply is shown in FIG. In this figure, 51 is an uninterruptible power supply, 52 is a load, 53 is an input circuit breaker, 54 is an output switch, 55 is a bypass circuit, and 56 is a switching circuit. In this figure, the uninterruptible power supply 51
The failure detection circuit 29 in the
When the uninterruptible power supply unit 51 is stopped via the operation stop circuit 27 regardless of the state, the input circuit breaker 53 is opened, the output switch 54 is commanded by the switching circuit 56, and the input AC power supply 11 is bypassed. Power is supplied to the load 52 via the circuit 55.

(Problems to be Solved by the Invention) As described above, when the failure detection circuit 29 performs the failure protection detection, the load power supply from the uninterruptible power supply 51 is stopped, and the input AC power supply 11 supplies the load via the bypass circuit 55. While the power was being supplied to the load 52, the failure cause investigation and recovery work were being performed.

However, since the conventional failure detection circuit 29 performs failure protection simply by using detection levels such as voltage and current, if the uninterruptible power supply 51 stops load power supply due to a transient failure, for example, It was difficult to determine the cause of the failure, and it took a long time to recover.

If the restoration work is prolonged, the probability of occurrence of an instantaneous interruption or overvoltage in the input AC power supply 11 increases, and if the load is extremely public, such as a large computer, the restoration time is required to be reduced as much as possible. .

Accordingly, an object of the present invention is to be made in view of the above-described point. When the failure detection circuit 29 performs the failure protection detection, it is determined whether the failure is a transient failure or a permanent failure. It is an object of the present invention to provide an uninterruptible power supply capable of reducing the recovery time by determining the power supply.

[Means for Solving the Problems] In order to achieve the above object, the present invention converts AC power input from an AC power supply into DC power by a rectifier, and converts the DC power to a voltage reference. A main circuit is configured to be converted to AC power by an inverter controlled to be supplied to a load from an output terminal, and when the AC power is lost or the output voltage falls below a predetermined voltage, a battery is connected to the inverter. In an uninterruptible power supply adapted to supply DC power, an AC voltage detector for detecting an overvoltage or undervoltage of the AC power supply, a DC voltage detector for detecting an overvoltage or undervoltage of the output voltage of the rectifier, and the inverter DC overcurrent detector that detects overcurrent input to
An inverter overcurrent detector that detects an output overcurrent of the inverter, an output overvoltage detector that detects an overvoltage of a voltage output from the output terminal, an overcurrent detector that detects an overcurrent of a current output from the output terminal, Various protection detectors such as a battery voltage detector for detecting a drop in the battery voltage and a control power loss detector for detecting a loss of control power for controlling the inverter, and detection signals are input from the various protection detectors, respectively. Fault detection means for detecting whether the rise of the current or voltage is steep or slow based on the generation timing of the detection signal, the level or the rate of change, and a failure detection signal having a steep rise of the current or voltage from the failure detection means. The failure is determined to be a permanent failure, and a slow failure detection signal is input to determine a transient failure. When it is judged the fault transient by the failure determining means, in which so as to supply power to the load through the bypass circuit from the AC power source.

(Operation) In the uninterruptible power supply having such a configuration, the voltage is detected by various protection detectors such as a voltage detector and a current detector provided in each part of a main circuit from an AC power supply to an output terminal to a load. And the detection signal is detected by the failure detection means as to whether the rise of the voltage or current is steep or slow, and based on the failure detection signal, the failure determination means determines whether the failure is transient or permanent. In the case of a transient failure, the load is supplied from the AC power supply to the load through the bypass circuit, so that failure detection with enhanced protection against voltage or current of each part of the uninterruptible power supply system is possible. In addition, in the event of a temporary failure, restarting the uninterruptible power supply system does not cause any problems, and there is no need to investigate the cause of the failure. Stable power can be supplied.

(Example) An example of the present invention is shown in FIG. In this figure, the components denoted by the same reference numerals as those in FIGS. 4 and 5 which are the embodiments of the prior art are the components having the same functions, and the description thereof will be omitted.
As a component added in FIG. 1 as the present embodiment, reference numeral 57 is a failure determination circuit.

In order to explain the operation of the embodiment shown in FIG.
This will be described below with reference to the current waveforms in FIG. Second
The current waveform in the figure shows the detected current waveform of the inverter overcurrent detector 36 provided in FIG. In i ₃₆ the detection current waveform of the inverter overcurrent detector 36, in each case a second view of the time t ₁ very steep current i ₁ rise of the or rise of gradual current i ₂ flows through, over It is assumed that the current detection level has been reached. Conventionally, the flow of such a current is detected by the failure detector 29 as described in FIG. 5, the uninterruptible power supply 51 is stopped, and the power supply to the load 52 is simply switched to the power supply from the bypass circuit 55. there were. In the present invention a rapid current rise overcurrent such as a second diagram of the current i ₁ of the waveform is high possibility of such components defective rare short or the PWM controller 24 of the inverter transformer 14, the uninterruptible power supply 51 It is presumed to be a permanent failure related to a component failure inside the.

The other gentle current rise overcurrent such as a second view of the current i ₂ of the waveform of the overcurrent rise inverter transformer 14
As a result, the current i ₂ that rises more slowly than the rise determined by this reactance does not have a rare short circuit of the inverter 14 and is estimated to be a failure due to some factor on the output terminal 15 side. If the cause is eliminated, the uninterruptible power supply 51 operates again and can supply power to the load 52. Such a failure is determined to be a transient failure.

In Figure 1, the failure detection circuit 29 receives various detection signals of the protection detector, failure detection circuit from the level and rate of change of the detection signal 29 and the second drawing current rise suddenly overcurrent such as i ₁ if the detection signal of the overcurrent 1, give rise gentle overcurrent if it detection signal of the overcurrent 2 such as current i ₂ to the fault determination circuit 57. Based on whether the overcurrent detection signal is overcurrent 1 or overcurrent 2, the failure determination circuit 57 determines whether the failure is permanent or transient.

Also, among the protection detectors provided inside the uninterruptible power supply 51, a protection detector for detecting only a permanent failure is provided, and when the control power supply failure detector 40 operates, the control circuit power supply is provided. When the control power supply loss detector 40 is activated due to a permanent failure, the failure detection circuit 29 detects a failure. Judge as failure.

As described above, since the failure determination circuit 57 determines whether the failure is permanent or temporary, the recovery is easy even if the uninterruptible power supply 51 is stopped once. That is, when the transient failure is determined by the failure determination circuit 57, even if the power supply to the load 52 is once switched to the bypass circuit 55, if the cause of the transient failure is removed, the uninterruptible power supply Re-run 51 and load 52
To the power supply can be restarted by the uninterruptible power supply 51. As described above, the failure detection circuit 57 of the present invention determines and detects a transient failure or a permanent failure by the operation of the failure determination circuit 57, which significantly reduces the failure recovery time of the uninterruptible power supply after the failure occurs. Clearly, it can be shortened.

Another embodiment of the present invention will be described with reference to FIG. FIG. 3A shows a case where the current flowing through the output terminal 15 has a lagging power factor, and FIG. 3B shows a case where the current flowing through the output terminal 15 has a leading power factor. In this figure i
₃₇ detection current of output overcurrent detector 37, i ₃₆ is the detection current of the inverter overcurrent detector 36. Since the current i ₃₆ for detecting the inverter overcurrent detector 36 is a current equivalent i ₁₉ of AC filter capacitor 19 is vectorially combining the detected current i ₃₇ of the output overcurrent detector 37, the detection current i is delayed rate ₃₆ and i
_Although the size of ₃₇ does not differ greatly, in the case of a leading power factor, the detected current i ₃₆ is significantly larger than i ₃₇ . Therefore, even if the detection current level of the output overcurrent detector 37 is not at the overcurrent level, the detection current level of the inverter overcurrent detector 36 may detect an overcurrent. In such a case, the fault detection circuit 29 detects the overcurrent of the inverter output overcurrent detector 36, and checks whether the detected current level of the output overcurrent detector 37 has increased to a predetermined value or more. If the detection signal is sent to the determination circuit 57 and the failure determination circuit 57 determines it, it is determined whether the overcurrent is due to a short circuit of the inverter transformer 14 or the like, or the overcurrent due to the power factor of the load 52 as described above. it can. Thus, when a failure is detected by the failure detection circuit 29, the occurrence timing of the level or change of the detection signal of another protection detector may be checked to determine whether or not the failure is transient.

In addition, it is apparent that various modifications can be made within the gist of the present invention.

[Effects of the Invention] According to the present invention, even if an uninterruptible power supply generates an internal failure, a failure determination circuit is provided to determine the generation timing, level, change rate, and the like of detection signals of various protection detectors. Thus, it is possible to provide an uninterruptible power supply device that can easily recover after an internal failure has occurred since the output signal is used to determine whether the failure is transient or permanent.

In particular, most internal failures such as uninterruptible power supplies are mostly transient failures, so the equipment can be restarted in the event of a transient failure without requiring a long-term failure stop. Stable power can be immediately supplied from the device to the load. For this reason, it is possible to minimize a decrease in the reliability of a power supply of a large computer or the like due to a long-term failure cause investigation as in the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 and 3 are detection signal waveform diagrams for explaining the operation of the present invention, and FIGS. 4 and 5 are prior art uninterruptible power supplies. FIG. 2 is a block diagram illustrating a configuration of a power supply device. 11 Input AC power supply, 12 Rectifier, 13 Inverter, 14 Inverter transformer, 15 Output terminal, 16
Battery, 17 Switch, 18 DC filter capacitor, 19 AC filter capacitor, 20 Voltage reference, 21
…… Output voltage detector, 22 …… Voltage controller, 23 …… Output frequency controller, 24 …… PWM controller, 25 …… Gate amplifier, 2
6 ... Control circuit power supply, 27 ... Operation stop circuit, 28 ... Operation stop command, 29 ... Fault detection circuit, 30 ... Fuse, 31 ...
... Shunt, 32 ... Input voltage detector, 33 ... DC voltage detector, 34 ... Fuse blow detector, 35 ... DC overcurrent detector, 36 ... Inverter overcurrent detector, 37 ... Output Overcurrent detector, 38 ... Output overvoltage detector, 39 ... Battery voltage detector, 40 ... Control power loss detector, 51 ... Uninterruptible power supply, 52 ... Load, 53 ... Input circuit breaker , 54 output switcher, 55 bypass circuit, 56 switching circuit, 57
Failure determination circuit.

Claims (1)

(57) [Claims] An AC power input from an AC power supply is converted into DC power by a rectifier, and the DC power is converted into AC power by an inverter controlled so that an output voltage becomes a voltage reference, and a load is output from an output terminal. An uninterruptible power supply device comprising a main circuit for supplying AC power to the inverter and supplying DC power from a battery to the inverter when the AC power supply is lost or the output voltage falls below a predetermined voltage. Voltage detector for detecting overvoltage or undervoltage, DC voltage detector for detecting overvoltage or undervoltage of the output voltage of the rectifier, DC overcurrent detector for detecting overcurrent input to the inverter, output of the inverter An inverter overcurrent detector for detecting an overcurrent; an output overvoltage detector for detecting an overvoltage of a voltage output from the output terminal; Various protection detections such as an overcurrent detector for detecting an overcurrent of the output current, a battery voltage detector for detecting a voltage drop of the battery, and a control power loss detector for detecting a loss of control power for controlling the inverter. A detection signal from each of the various protection detectors, and a failure detection means for detecting whether the rise of current or voltage is steep or slow based on the generation timing, level, or rate of change of the detection signal; Failure determination means for determining that the failure is a permanent failure when a failure detection signal having a steep rise in current or voltage is input from the means, and determining that the failure is transient when a slow failure detection signal is input. When it is determined as a transient failure by the failure determination means,
An uninterruptible power supply device wherein power is supplied from the AC power supply to the load through a bypass circuit.