JP2017093210A - Uninterruptible power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable uninterruptible power supply device capable of cost reduction by instantaneously switching between bypass power supply and converter power supply. SOLUTION: In a non-disruptive power supply device including a double conversion type converter power supply circuit 100 and a bypass power supply circuit 200 for supplying AC power of an AC power supply to a load via an AC switch unit 201, the AC switch unit. The 201 is configured by connecting a main switch 221 having a self-extinguishing function and an auxiliary switch 210 having a large overload withstand capacity in parallel without having a self-extinguishing function, and is a converter power supply circuit when the AC power supply is sound. When power is supplied to the load by either 100 or the main switch 221 and an abnormality occurs in the converter power supply circuit 100 and the power supply path is switched to the bypass power supply circuit 200, the auxiliary switch 210 is switched to the converter power supply circuit 100. It is turned on at the same time as the operation is stopped, and is turned off after the main switch 221 is turned on. [Selection diagram] Fig. 1

Description

  The present invention includes a converter power supply circuit that supplies power to a load by a power converter that performs AC / DC / AC conversion, and a bypass power supply circuit that supplies power to the load by the operation of an AC switch unit. The present invention relates to a switching uninterruptible power supply (hereinafter also referred to as UPS).

Conversion devices such as UPS and frequency converters equipped with so-called double conversion type power converters that perform AC / DC / AC conversion in order to supply highly reliable power to electrical and electronic devices of various specifications It is used.
In recent years, due to increasing interest in energy saving, it is desired to increase the efficiency of these converters. As one means for this, converters mainly for overseas use a high-efficiency mode in which power is supplied from the bypass power supply circuit to the load. The provided UPS is becoming mainstream.

As this type of UPS, for example, the one described in Patent Document 1 is known.
The UPS bypass power supply circuit described in Patent Document 1 uses an AC switch unit in which two bipolar transistors are connected in reverse series. In this document, an IGBT (insulated gate type) is used instead of the bipolar transistor. It is described that a bipolar transistor) may be used.

Japanese Patent Laid-Open No. 10-75581 / Patent No. 3624568 (paragraph [0047], FIG. 1, FIG. 6, FIG. 11 to FIG. 13)

However, when two IGBTs are used in reverse series connection as an AC switch unit in the bypass power supply circuit, the following problems occur.
In other words, since the overcurrent withstand capability of the IGBT is significantly smaller than that of, for example, a thyristor, a short circuit that flows through the bypass power supply circuit when a short circuit occurs on the load side during power supply from the converter power supply circuit and switches to the bypass power supply circuit. There is a risk that the IGBT of the AC switch unit may be damaged by the current.

In other large-capacity UPSs, a thyristor capable of continuous energization as shown in FIGS. 11 to 13 of Patent Document 1 is used as an AC switch section of a bypass power supply circuit, or a thyristor rated for a short time. And a mechanical contact such as a contactor or a breaker connected in parallel.
However, since the thyristor does not have a self-extinguishing function, when switching the power feeding path from the bypass power feeding circuit to the converter power feeding circuit, switching time for one cycle of the commercial power supply is required at the maximum, and contactors and breakers are also required. There is a problem that it takes time to operate the contact even when using. If it takes time to switch the power supply path in this way, there is a risk that power supply to the load cannot be continued if an accident such as a line short circuit or a ground fault occurs on the input side. It becomes difficult.
Furthermore, when a thyristor is used in the AC switch section of the bypass power supply circuit, the thyristor can be turned off instantaneously by using the arc extinguishing circuit, but the cost and size of the device are greatly increased by adding the arc extinguishing circuit. There is a problem of doing.

  Therefore, the problem to be solved by the present invention is to provide an uninterruptible power supply apparatus that can instantaneously switch between a bypass power supply circuit and a converter power supply circuit while maintaining high reliability, and that can reduce costs. There is.

In order to solve the above-mentioned problem, an uninterruptible power supply according to claim 1 includes a rectifier that converts AC power of an AC power source into DC power, an inverter that converts DC power output from the rectifier into AC power, A converter feeding circuit having switching means connected between the AC output side and the load, and power storage means connected to a DC intermediate circuit between the rectifier and the inverter;
A bypass power supply circuit that supplies the AC power of the AC power source to the load via an AC switch unit,
The AC switch part is configured by connecting in parallel a main switch having a self-extinguishing function and an auxiliary switch having a large overload capacity without having a self-extinguishing function,
When an abnormality occurs in the converter power supply circuit and the power supply path is switched to the bypass power supply circuit, the auxiliary switch is turned on at the same time as the operation of the inverter is stopped and an opening command for the opening / closing means is generated. Is turned off, and the auxiliary switch is turned off after the main switch is turned on.

  An uninterruptible power supply according to a second aspect is the uninterruptible power supply according to the first aspect, wherein the auxiliary switch is constituted by an anti-parallel circuit of two thyristors.

  An uninterruptible power supply according to a third aspect is the uninterruptible power supply according to the first aspect, wherein when the AC power supply is healthy, the power is supplied to the load via either the converter power supply circuit or the main switch. To do.

  The uninterruptible power supply according to claim 4 is the uninterruptible power supply according to claim 1, wherein when the load is supplied from the bypass power supply circuit to the load, the auxiliary switch is turned off, and the opening / closing means is It is to turn on.

  The uninterruptible power supply according to claim 5 is the uninterruptible power supply according to claim 4, wherein the main switch is turned off at the same time when the power supply path is switched from the bypass power supply circuit to the converter power supply circuit. The operation of the inverter is started.

According to the present invention, an AC switch unit provided in a bypass power supply circuit is connected in parallel with a main switch having a self-extinguishing function and an auxiliary switch made of a thyristor or the like having no self-extinguishing function but having a large overload capability. With this configuration, it is possible to instantaneously switch the power supply path between the bypass power supply circuit with high conversion efficiency and the converter power supply circuit with high power quality without causing damage to the main switch.
Further, since it is not necessary to provide an arc extinguishing circuit in the auxiliary switch, there is no fear of increasing the cost.

It is a circuit diagram of an uninterruptible power supply concerning an embodiment of the present invention. FIG. 2 is a circuit diagram illustrating a first embodiment of an AC switch unit in FIG. 1. It is a circuit diagram which shows the 2nd Example of the alternating current switch part in FIG. It is a circuit diagram which shows the 3rd Example of the alternating current switch part in FIG. It is a timing chart at the time of switching a feed path from a converter feed circuit to a bypass feed circuit in normal time. It is a timing chart at the time of switching an electric power feeding path from a converter electric power feeding circuit to a bypass electric power feeding circuit at the time of abnormality occurrence. It is a timing chart at the time of switching a electric power feeding path from a bypass electric power feeding circuit to a converter electric power feeding circuit in normal time. It is a timing chart at the time of switching an electric power feeding path from a bypass electric power feeding circuit to a converter electric power feeding circuit at the time of abnormality occurrence.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram of a UPS according to this embodiment. In FIG. 1, 100 is a converter power supply circuit configured between the AC input terminal 11 and the AC output terminal 20, and 200 is a bypass configured between the bypass input terminal 12 and the AC output terminal 20. This is a power feeding circuit. The AC input terminal 11 and the bypass input terminal 12 are connected to the same three-phase AC power supply (commercial power supply) (not shown), and a load (not shown) is connected to the AC output terminal 20.

  In the converter power supply circuit 100, a rectifier 102 serving as an AC / DC converter is connected to the AC input terminal 11 via an AC filter 101 including a capacitor and a reactor. A DC input side of an inverter 104 as a DC / AC converter is connected to a DC output side of the rectifier 102 via a smoothing capacitor 103.

A DC intermediate circuit provided with the smoothing capacitor 103 is connected to a DC input terminal 30 via a DC / DC converter 301 such as a chopper, and the DC input terminal 30 is connected to a storage battery (not shown). Are connected. Here, the DC / DC converter 301, the DC input terminal, and the power storage device constitute power storage means in the claims.
Further, the AC output side of the inverter 104 is connected to the AC output terminal 20 via an AC filter 105 composed of a capacitor and a reactor and a contactor (or breaker) 106 as an opening / closing means.

On the other hand, the bypass power supply circuit 200 includes an AC switch unit 201, and the AC switch unit 201 is configured as in the first to third embodiments shown in FIGS.
That is, the AC switch unit according to the first to third embodiments includes a main switch having a semiconductor switching element such as an IGBT having a self-extinguishing function and an auxiliary switch composed of an antiparallel circuit of two thyristors. Connected to and configured. Here, the thyristor has a larger short-time overload capability (short-time rating) than a semiconductor switching element such as an IGBT.

First, FIG. 2 shows an AC switch unit 201A of the first embodiment.
In FIG. 2, 12U, 12V, and 12W are input terminals connected to each phase (U, V, and W phase) of the bypass input terminal 12, and 20U, 20V, and 20W are outputs connected to each phase of the AC output terminal 20. At the end.
Since the configuration of the AC switch section of each phase is the same, the U phase will be described as an example with reference to FIG. 2, and an IGBT 221a having an anti-parallel diode between the input terminal 12U and the output terminal 20U will be described. A main switch 221 in which 221b is connected in anti-series and an auxiliary switch 210 in which thyristors 210a and 210b are connected in anti-parallel are connected in parallel.

Next, FIG. 3 shows an AC switch unit 201B of the second embodiment.
The AC switch unit 201B includes, for example, a main switch 222 having reverse breakdown voltage by connecting reverse blocking IGBTs (RB-IGBT) 222a and 222b in reverse parallel between the U-phase input terminal 12U and the output terminal 20U. And the auxiliary switch 210 are connected in parallel.

FIG. 4 shows an AC switch unit 201C of the third embodiment.
The AC switch unit 201C includes, for example, a main switch 223 including a diode bridge 223a and an IGBT 223b having an antiparallel diode connected between the output terminals between the U-phase input terminal 12U and the output terminal 20U. The auxiliary switch 210 is connected in parallel.

  In the first to third embodiments, the main switches 221, 222, and 223 having a self-extinguishing function are turned on at the time of bypass power supply, and when the power supply path is switched from the bypass power supply circuit 200 to the converter power supply circuit 100. The auxiliary switch 210 using a thyristor that can be turned off instantaneously and has a large overcurrent withstand capability is short-circuited even when the power supply path is switched from the converter power supply circuit 100 to the bypass power supply circuit 200 due to a short circuit of a load or the like. There is no worry of being damaged by electric current.

Next, the power supply path switching operation in this embodiment will be described.
First, FIGS. 5 and 6 are timing charts in the case where the power feeding path is switched from the converter power feeding circuit 100 to the bypass power feeding circuit 200. Note that the AC power supply connected to the AC input terminal 11 and the bypass input terminal 12 is healthy and the power supply voltage is within a predetermined range. The following description is the same when any of the aforementioned AC switch units 201A, 201B, and 201C is used.

FIG. 5 shows a case where the power supply path is switched to the bypass power supply circuit 200 side when the converter power supply circuit 100 supplies power by normal operation.
At time t ₁ , an ON command is sent to the main switch (221, 222, or 223) of the AC switch unit, the power feeding path is shifted to the bypass power feeding circuit 200 side, and then a pulse off command for the inverter 104 is generated at time t _2. Switch the power supply path.
In this case, the auxiliary switch 210 remains off, and the contactor 106 remains on because the AC power supply is healthy.

FIG. 6 shows an operation at the time of occurrence of an abnormality in which the inverter 104 or the like in the converter power supply circuit 100 has failed.
When detecting an abnormality at time t _1, a pulse-off command of the inverter 104, on command of the auxiliary switch 210, the OFF command of the contactor 106, simultaneously and promptly produces.
By the time the contactor 106 is turned off completely, usually, because the tens [ms] about delayed off command occurs, the response of the contactor 106 is turned off is obtained at time t _2.

During the time t _{1 to} t _2, an accident current may flow through the auxiliary switch 210, but the thyristor constituting the short-time rated auxiliary switch 210 has a sufficient overload capability. Therefore, after confirming the off response from the contactor 106 to turn on the main switch for bypass feeding at time t _3, shorter set the on time of the auxiliary switch 210 by turning off the auxiliary switch 210 in the subsequent time t ₄ By doing so, the power supply path can be switched in a short time without fear of the auxiliary switch 210 being destroyed.

Next, FIGS. 7 and 8 are timing charts in the case where the power feeding path is switched from the bypass power feeding circuit 200 to the converter power feeding circuit 100.
FIG. 7 shows a case where the power supply path is switched to the converter power supply circuit 100 side when the AC power supply is healthy and the bypass power supply circuit 200 supplies power through normal operation.
After migrating generated by the power supply path to pulse-on command to the inverter 104 to the converter feed path 100 side at time t _1, it generates an off command to the main switch at time t _2.
In this case, the auxiliary switch 210 remains off, and the contactor 106 remains on because the AC power supply is healthy.

FIG. 8 shows an operation when power supply from the bypass power supply circuit 200 becomes impossible due to an abnormality in the AC power supply (power failure, voltage drop, etc.).
When detecting an abnormality at time t _1, a pulse-on command for the inverter 104, simultaneously and promptly produces the OFF command to the main switch of the AC switch section. Thereby, the inverter 104 can convert the DC output voltage of the DC / DC converter 301 of FIG. 1 into an AC voltage, and can maintain power supply to the load.
The operations of the auxiliary switch 210 and the contactor 106 during this time are the same as those in FIG.

  Since the thyristor constituting the auxiliary switch 210 does not have a self-extinguishing function, the half cycle may not be turned off when an abnormality such as a power supply short-circuit occurs. However, in this embodiment, an IGBT having a self-extinguishing function is used as the main switch even if the overload capability is small. Therefore, when an abnormality occurs on the bypass power supply circuit 200 side due to the AC power supply, the power supply path is set. It is possible to instantaneously switch to the converter power supply circuit 100 side.

  The present invention can be used not only for the three-phase uninterruptible power supply described as the embodiment but also for a single-phase uninterruptible power supply.

11: AC input terminal 12: Bypass input terminal 12U, 12V, 12W: Input terminal 20: AC output terminal 20U, 20V, 20W: Output terminal 30: DC input terminal 100: Converter feed circuit 101, 105: AC filter 102: Rectifier 103: smoothing capacitor 104: inverter 106: contactor 200: bypass power supply circuits 201, 201A, 201B, 201C: AC switch unit 210: auxiliary switches 210a, 210b: thyristors 221, 222, 223: main switches 221a, 221b, 222a, 222b, 223b: IGBT
223,224: Reverse blocking IGBT
223a: Diode bridge 301: DC / DC converter

Claims (5)

A rectifier that converts AC power of an AC power source into DC power, an inverter that converts DC power output from the rectifier into AC power, switching means connected between an AC output side of the inverter and a load, and An electricity storage means connected to a DC intermediate circuit between the rectifier and the inverter;
A bypass power supply circuit that supplies the AC power of the AC power source to the load via an AC switch unit,
The AC switch part is configured by connecting in parallel a main switch having a self-extinguishing function and an auxiliary switch having a large overload capacity without having a self-extinguishing function,
When an abnormality occurs in the converter power supply circuit and the power supply path is switched to the bypass power supply circuit, the auxiliary switch is turned on at the same time as the operation of the inverter is stopped and an opening command for the opening / closing means is generated. And the auxiliary switch is turned off after the main switch is turned on. In the uninterruptible power supply device according to claim 1,
The uninterruptible power supply apparatus, wherein the auxiliary switch is constituted by an anti-parallel circuit of two thyristors. In the uninterruptible power supply device according to claim 1,
An uninterruptible power supply that supplies power to the load via either the converter power supply circuit or the main switch when the AC power supply is healthy. In the uninterruptible power supply device according to claim 1,
An uninterruptible power supply apparatus that turns off the auxiliary switch and turns on the opening / closing means when power is supplied to the load from the bypass power supply circuit. In the uninterruptible power supply according to claim 4,
An uninterruptible power supply apparatus, wherein when the power supply path is switched from the bypass power supply circuit to the converter power supply circuit, the operation of the inverter is started simultaneously with turning off the main switch.

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