JP2941527B2 - Uninterruptible power system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uninterruptible power supply having a built-in high-input power factor converter, for example. The present invention relates to an uninterruptible power supply device having improved reliability.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional uninterruptible power supply. A first power converter (hereinafter, referred to as a converter) CNV1 composed of, for example, a high input power factor converter in which a reactor ACL1 and a switching element are configured in a bridge shape is connected to the AC input power supply 1, and an output terminal thereof (DC voltage VDC). Is connected to the smoothing capacitor DCC and the battery Batt. Further, a second power converter (hereinafter, referred to as a converter) CNV2 composed of, for example, a PWM inverter in which the switching elements are formed in a bridge shape is connected, and its AC output is connected to a winding T1 via a switch SW5.
1 of the three-winding transformer T1 having the first, T12, and T13.
To the winding T11.

On the other hand, from the AC input power supply 1 to the switch SW6
Commercial direct feed circuit (bypass circuit) BP configured via
S is connected to the second winding T12 of the transformer T1. Further, an AC filter capacitor ACC is connected to the third winding T13 of the transformer T1, and an output terminal O of the uninterruptible power supply is connected.
UT.

In the conventional uninterruptible power supply configured as described above, in normal operation, the input current of the converter CNV1 has the same phase as the AC input power supply 1, that is, a sinusoidal current waveform with a power factor = 1. And the battery Batt is charged while controlling the DC voltage VDC to a predetermined value.

On the other hand, in the converter CNV2, the DC voltage VDC is input, pulse width modulation (PWM) control is performed so as to obtain a stable sine wave in phase with the AC input power supply 1, and the leakage inductance L of the transformer T1 (shown in FIG. And an AC filter composed of an AC filter capacitor ACC to remove high-frequency components by switching of the converter CNV2 to obtain a sine wave output of a commercial frequency. At the time of a power failure, the converter CN is connected to the battery Batt as a DC input.
V2 is operated at a constant voltage and a constant frequency to obtain a sine wave output of a commercial frequency, thereby achieving uninterrupted power.

If the converter CNV1 or the converter CNV2 becomes abnormal (failure), the operation of the CNV1 and CNV2 is stopped, and the switches SW5 and SW6 are closed and the switches SW6 are closed, so that they are connected via the commercial direct feed circuit BPS. To continue load power supply.

[0007]

Thus, the converter CN
When V1 or the converter CNV2 is out of order, the following problems occur because the load power supply is continued via the commercial direct feed circuit BPS. (1) When a power failure occurs, the load power supply stops because the operation of the converter CNV2 is stopped.

(2) Normally, the load of the uninterruptible power supply is a non-linear load of a computer or the like, and the operation of the converter CNV1 is stopped, so that the harmonic current on the load side flows out to the AC input power supply as it is. I will.

It is an object of the present invention to provide two converters CNV1 even if converter CNV1 or converter CNV2 fails.
1. Except in the worst case where the converter CNV2 simultaneously fails, a healthy converter is identified and its operation mode is changed to continue the backup operation at the time of AC input power failure and to discharge the harmonic current of the load. And to provide a highly reliable uninterruptible power supply.

[0010]

In order to achieve the above object, according to the present invention, there is provided a direct feeder circuit capable of supplying AC power from an AC input power supply to a load, and a converter for converting the AC power into DC power, A first power converter operable as an active filter for removing a component, and an active power converter electrically connected to the first power converter for converting the DC power into AC power and removing harmonic components. A second power converter operable as a filter and supplying AC power to the load; a second power converter connected between the second power converter and the first power converter; An uninterruptible power supply comprising: a battery that is charged when the power converter is normal; a converter mode control circuit that selectively controls an operation mode of each of the first and second power converters; Input power and Serial first between the power converter, the first
And a second power converter, between the second power converter and the load, disposed in the direct-feed circuit, a plurality of circuit open circuit elements capable of opening the corresponding circuit, and the AC input power supply An AC input monitoring circuit that monitors a power failure state, a converter abnormality detection circuit that detects an abnormality of each of the first and second converters, and outputs a signal corresponding to the detection signal; Based on an output signal from a converter abnormality detection circuit, an open circuit command is output to one of the electric circuit open circuit elements, and the converter mode control circuit on the sound side of the first and second power converters And a switch control circuit for outputting an operation command to the switch.

[0011]

According to the present invention, when an abnormality is detected in the first power converter, the operation is stopped, the electric circuit opening element is opened to isolate the abnormal part, and the load power is supplied via the direct feed circuit. continue. On the other hand, by changing the operation mode of the second power converter that has been operated as an inverter and operating as an active filter, the harmonic current on the load side is absorbed, and the current of the AC input power supply is maintained in a sine wave shape. The DC voltage, that is, the battery charging voltage is controlled.

Further, when a power failure occurs in the AC input power source, the second power source, which is operated as an active filter, is opened by opening a circuit opening element disposed between the AC input power source and the first power converter. By changing the operation mode of the converter again and operating as an inverter, the DC power of the battery is converted into stable AC power at a constant voltage and constant frequency, and the load power supply is continued.

When an abnormality is detected in the second power converter, the operation is stopped, the electric circuit open circuit element is opened to isolate the abnormal part, and the load power supply is continued via the direct feed circuit. On the other hand, by changing the operation mode of the first power converter that has been operated as a converter and operating as an active filter, it absorbs the harmonic current on the load side and keeps the AC input power supply current in a sine wave shape, The voltage, that is, the battery charging voltage is controlled.

Further, when a power failure occurs in the AC input power supply, a circuit open circuit element disposed between the AC input power supply and the first power converter is opened to operate the first power supply as an active filter. By changing the operation mode of the converter again and operating as an inverter, the DC power of the battery is converted into stable AC power at a constant voltage and constant frequency, and the load power supply is continued.

[0015] Thus, even if the first power converter or the second power converter fails, a healthy power converter is identified except in the worst case where two power converters fail simultaneously. Since the operation mode is changed, the backup operation at the time of the AC input power failure can be continued, and the outflow of the harmonic current of the load can be prevented, so that the reliability is improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a basic configuration diagram showing a first embodiment of the present invention. The main circuit configuration of the uninterruptible power supply of the present embodiment is as follows. A first converter comprising, for example, a high-input power factor converter in which a first switch SW1 is connected to an AC input power supply 1, a series circuit including a second switch SW2 and a reactor ACL1, and a switching element is formed in a bridge shape. CNV1 and third switch S
W3, the smoothing capacitor DCC, the battery Batt, and the fourth
DC switch VDC composed of a switch SW4, a second converter CNV2 composed of, for example, a PWM inverter having switching elements configured in a bridge shape, and a fifth switch S
W5 is connected to the first winding T11 of the transformer T1 having three windings T11, T12 and T13, and further connected to the first switch SW1 via the sixth switch SW6.
And an AC filter capacitor ACC connected to the third winding T13 of the transformer T1 to serve as an output terminal.

The control circuit of the uninterruptible power supply of this embodiment
It is configured as follows. AC input monitoring circuit 10 for monitoring the state of AC input power supply 1, converter abnormality detecting circuit 11 for detecting abnormality of first and second converters CNV1 and CNV2, AC input monitoring circuit 10 and converter abnormality A switch control circuit 12 for controlling the opening and closing of the first to sixth switches SW1 to SW6 based on an output signal from the detection circuit 11, a converter mode control circuit 13 for controlling operation modes of the converters CNV1 and CNV2, , The control circuit 14 of the first converter CNV1, and the second converter CNV
2 control circuits 15. The control circuit 14 controls the control circuit unit 2 as an operation mode of the high input power factor converter.
0, a control circuit section 21 as an active filter operation mode, and a control circuit section 22 as a CVCF inverter operation mode. The control circuit 15 controls the CVC
It has a control circuit section 30 in an F inverter operation mode and a control circuit section 31 in an active filter operation mode.

Normally, the switches SW1 to SW5 are closed, the converter CNV1 is operated as a high input power factor converter, and its input current is in phase with the AC input power supply 1, that is, a sinusoidal current waveform with a power factor = 1. The battery BATT is charged while controlling the DC voltage VDC to a predetermined value.

On the other hand, the second converter CNV2 is operated as a PWM inverter, and receives a DC voltage VDC as input, and performs pulse width modulation (PWM) control so as to obtain a stable sine wave in phase with an AC input power supply. In this case, a high frequency component due to switching of the converter CNV2, that is, a PWM inverter is removed by an AC filter including a leakage inductance L of a transformer and an AC filter capacitor ACC to obtain a sine wave output of a commercial frequency. Also, during a power outage,
PWM inverter C with battery Batt as DC input
The NV2 is operated at a constant voltage frequency (CVCF) to obtain a sine wave output of a commercial frequency to achieve uninterrupted power.

When an abnormality is detected in the high input power factor converter, which is the converter CNV1, the operation is stopped, and the switches SW1 and SW2 are opened to disconnect the abnormal part from the uninterruptible power supply, and SW6
Switch is closed and the commercial direct feed circuit (bypass circuit) B
Continue load power supply via PS.

On the other hand, by changing the operation mode of the second converter CNV2 which has been operated as a PWM inverter and operating as an active filter, it absorbs the harmonic current on the load side and maintains the AC input current in a sine wave shape. At the same time, it controls the DC voltage, that is, the charging voltage of the battery Batt.

Further, when a power failure occurs, the switch SW1 or SW6 is opened, and the operation mode of the converter CNV2, which has been operated as an active filter, is changed again.
By operating as an M inverter, the battery B
Att DC power is converted to stable AC power of constant voltage and constant frequency, and load power supply is continued.

In this case, not only the operation of the converter CNV2 as a mere active filter, but also the adjustment of the AC voltage (parallel processing technology) during the operation of the commercial direct feed circuit BPS is possible.

Further, the PWM which is the second converter CNV2
When an abnormality is detected in the inverter, the operation is stopped, and the switches SW4 and SW5 are opened to disconnect the abnormal part from the uninterruptible power supply, and the switch SW
6 is closed, and the load power supply is continued via the commercial direct delivery circuit BPS.

On the other hand, by changing the operation mode of the converter CNV1, which has been operated as a high input power factor converter, and operating as an active filter, it absorbs the harmonic current on the load side and converts the AC input power supply current into a sine wave. At the same time, the DC voltage, that is, the charging voltage of the battery Batt is controlled.

Further, when a power failure occurs, the switch SW1 is opened, the operation mode of the converter CNV1, which has been operated as an active filter, is changed again, and the converter is operated as a PWM inverter. Convert to constant frequency stable AC power and continue load power supply. Note that two converters CNV1 and CNV2
, At the same time, the load power supply is continued via the commercial direct-feed circuit BPS as in the prior art.

As described above, according to the present embodiment, the following effects can be obtained. In the case of a UPS failure, the load power supply is continued via the commercial direct feed circuit BPS. According to the present invention, unless the two converters CNV1 and CNV2 fail simultaneously,

(1) When a power failure occurs, one of the healthy converters CNV1 or CNV2 can be operated as a CVCF as a PWM inverter, and the battery can be backed up to continue load power supply.

(2) Normally, the load of the uninterruptible power supply is a non-linear load of a computer or the like. By operating either the sound converter CNV1 or CNV2 as an active filter, the harmonic current on the load side is reduced. It can be prevented from flowing out to the AC input power supply 1 as it is. Thus, in the first embodiment, a highly reliable uninterruptible power supply can be obtained.

FIG. 2 is a basic configuration diagram showing a second embodiment of the present invention. In FIG. 2, the switch SW in FIG.
2, SW3, SW4, SW5 are connected to fuses FU1, FU
2, FU3, and FU4. This simplifies the disconnection of the two converters CNV1 and CNV2 from the uninterruptible power supply device when the converters are abnormal, particularly when the switching elements of the converters are short-circuited or damaged.

In the first embodiment, the switches SW1, SW2, SW3, SW
4, SW5 and SW6 have been described as examples, but it goes without saying that at least a part thereof may be replaced with a semiconductor switch, a fuse or the like.

[0032]

According to the present invention, a healthy converter is identified except in the worst case where two converters fail simultaneously.
By changing the operation mode, it is possible to provide a highly reliable uninterruptible power supply having a function of continuing a backup operation at the time of an AC input power failure and preventing a harmonic current from flowing out of a load.

[Brief description of the drawings]

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

FIG. 2 is a basic configuration diagram showing a second embodiment of the uninterruptible power supply according to the present invention.

FIG. 3 is a basic configuration diagram showing an example of a conventional uninterruptible power supply.

[Explanation of symbols]

1: AC input power supply, SW1 to SW6: Switch, ACL
1: reactor, CNV1, CNV2: power converter, B
att ... battery, DCC ... smoothing capacitor, ACC ...
AC filter capacitor, T1 ... 3 winding transformer, 10
... AC input monitoring circuit, 11 ... Converter abnormality detection circuit, 12
... switch control circuit, 13 ... converter mode control circuit, 1
4 ... Control circuit of power converter CNV1, 15 ... Control circuit of power converter CNV2, 20 ... Control circuit part of high input power factor converter, 21, 31 ... Control circuit part of active filter, 22, 30 ... CVCF inverter Control circuit section.

Claims (1)

(57) [Claims] 1. A direct power supply circuit capable of supplying AC power from an AC input power supply to a load, and a first power converter operable as an active filter for converting the AC power into DC power and removing a harmonic component. And a first power converter, which is electrically connected to the first power converter, is operable as an active filter for converting the DC power to AC power or removing a harmonic component, and supplies AC power to the load. A second power converter, and a battery connected between the second power converter and the first power converter and charged when the first and second power converters are normal. A converter mode control circuit for selectively controlling an operation mode of each of the first and second power converters; and a converter between the AC input power supply and the first power converter. 1st and 2nd power Between the second power converter and the load, between the second power converter and the load, a plurality of circuit open-circuit elements capable of opening the corresponding circuit, and monitoring a power failure state of the AC input power supply. An AC input monitoring circuit; a converter abnormality detection circuit that detects an abnormality of each of the first and second converters and outputs a signal corresponding to the detection signal; and an AC input monitoring circuit and a converter abnormality detection circuit. And outputs an open command to one of the electric circuit open circuit elements based on the output signal from the first and second power converters, and issues an operation command to the converter mode control circuit on the sound side of the first and second power converters. And an uninterruptible power supply comprising: