JPS63305725A - Uninterruptive power supply - Google Patents

Abstract

PURPOSE:To improve efficiency, and to miniaturize and lighten a device by using a converter mounted on the input side as a diode rectifier while operating a transformer for insulation at high frequency. CONSTITUTION:When power is fed normally from a commercial power supply 2, a first inverter device 20 applies AC power at high frequency to a second inverter device 40 through a three-winding transformer 30, thus operating a load 60 by AC power output from the second inverter device 40. A battery 10 can be charged by AC power from the commercial power supply 2 by forward-conversion operating a forward and reverse converter 50 at that time. When the commercial power supply 2 gives out, the forward and reverse converter 50 instantaneously starts reverse-conversion operation, and power is fed from the battery 10, thus preventing the service interruption of the load 60.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention converts alternating current from an alternating current power source into alternating current of a desired voltage and frequency to supply power to a load, and also provides backup power in the event of a power outage to this alternating current power source. The present invention relates to an uninterruptible power supply device that can continuously supply power to a load using a battery.

[Conventional technology]

Electronic devices such as computers and office automation equipment generally operate by receiving power from a commercial power source, but these electronic devices do not like voltage or frequency fluctuations in the input power source, but they are particularly susceptible to power outages. Even a very short power outage (or a large voltage drop) will disrupt the functionality of the device. Therefore, such electronic devices receive AC power from an uninterruptible power supply.
We are trying to prevent damage caused by power outages.

FIG. 2 is a main circuit connection diagram showing a conventional example of an uninterruptible power supply system that is called a floating charging system. In FIG. 2, AC power from a commercial type a2 is input to a thyristor rectifier 4 via a transformer 3 which also serves as insulation for the main circuit, and the DC output from the thyristor rectifier 4 is transferred to a smoothing reactor 6. This is a so-called floating charging method in which the power is supplied to the transistor inverter 8 through the transistor inverter 8 and also supplied to the backup battery 10 to charge it.

The transistor inverter 8 converts input DC into AC with a desired voltage and frequency and supplies this AC power to the load 60. However, when the commercial power supply 2 is interrupted due to a power outage, the thyristor DC power is supplied to the transistor inverter 8 from the battery IO, which is connected to a so-called DC intermediate circuit that connects the DC side of the rectifier 4 and the DC side of the transistor inverter 8.
Interruption of AC power to the load 60 can be prevented.

In the conventional example of the floating charging method shown in FIG. 2, in order to supply DC power to the transistor inverter 8 via a DC intermediate circuit and to floatingly charge the battery 10, the input side has a voltage control function and a current control function. For example, a thyristor rectifier 4 is used to supply DC power to this DC intermediate circuit. Note that this DC intermediate circuit voltage needs to be able to maintain an appropriate value even with voltage fluctuations in the commercial power supply 2, so it is better than the DC voltage obtained by full-wave rectification of the AC voltage input to the SIRISK rectifier 4. A low value will also be selected.

Therefore, the transistor inverter 8 must also be of a low voltage, large current type.

FIG. 3 is a main circuit connection diagram showing a conventional example of an uninterruptible power supply equipped with a battery charging device. In Fig. 3, AC power from a commercial power source 2 is input to a diode rectifier 5 via a transformer 3 which also serves as insulation for the main circuit, and the ripple component of the DC output from the diode rectifier 5 is smoothed. After being absorbed and removed by a capacitor 7, the AC power is inputted to a transistor inverter 8, and the alternating current power having a desired voltage and frequency is converted and output from the transistor inverter 8, and is supplied to a load 60.

A series circuit of a battery 10 and a thyristor switch 15 is connected to the DC intermediate circuit, and when a power outage of the commercial power supply 2 is detected, the thyristor switch 15 is immediately activated by the operation of a control circuit (not shown). Since the load 60 is electrically conductive and supplies direct current power from the battery 10 to the transistor inverter 8, the operation of the load 60 can be continued without interruption (despite a power outage of the commercial power supply 2).

A charging transformer 11 and a charging rectifier 12 are provided on the secondary side of the transformer 3.
After absorbing and removing the ripple of the DC output by the smoothing capacitor 13, the chipper 14 connects the battery 1.
It is designed to obtain a DC voltage suitable for charging 0. Due to this chipper 14, the battery 10 is always in a fully charged state and is prepared for an unexpected power outage in the commercial type [2].

[Problem that the invention seeks to solve]

However, in the conventional example of the floating charging method shown in FIG. 2, although the main circuit configuration is simple, since the transistor inverter 8 is of a low voltage/high current type, the normal operating state (
In other words, in a state where AC power is being supplied from the commercial power source 2), the inverter efficiency of the transistor inverter 8 decreases. In addition, by controlling the phase of each thyristor that constitutes the thyristor rectifier 4, voltage fluctuations in the commercial power supply 2 are dealt with, so that the fundamental wave power factor of the input AC is reduced. Furthermore, since it is normal to electrically insulate the commercial 'IIH 2 and the battery 10, an isolation transformer 3 is provided in the commercial power supply 2, but since this transformer 3 operates at a commercial frequency, it is unnecessary. It has various drawbacks, such as being a factor that hinders the reduction in size and weight of power outage power supplies.

In addition, in the case of the conventional example equipped with the charging device shown in Fig. 3,
Poor transient characteristics, such as a delay in the operation of the SI risk switch 15 when the commercial power supply 2 is out of power and the power is switched to the battery 10, an inrush current that occurs at the time of switching, and rapid fluctuations in the DC voltage caused by this inrush current. It has the disadvantage of being an uninterruptible power supply. Furthermore, as in the case of the conventional example shown in Fig. 2, since the transformer 3 used for insulation is operated at the commercial frequency, it also has drawbacks that hinder the miniaturization and weight reduction of the uninterruptible power supply. .

Therefore, the purpose of this invention is to improve the efficiency and input power factor of an uninterruptible power supply during normal operation using AC power from a commercial power source, and to improve the electrical power between the commercial power source, battery, and output AC. The aim is to make the uninterruptible power supply smaller and lighter by making the insulating means smaller.

[Means for solving problems]

In order to achieve the above object, the uninterruptible power supply device of the present invention includes a first power exchange means that is connected to an AC power source and outputs an AC of a predetermined voltage and frequency, and a first power exchange means that is connected to an AC power source and outputs an AC of a predetermined voltage and frequency, and a a second power conversion means that outputs an alternating current with a frequency of , a forward/reverse converter capable of converting alternating current to direct current or converting direct current to alternating current, a human power winding, an output winding, and these input windings and output windings. and a third winding insulated from the transformer, and an input winding of the transformer is connected to the AC output side of the first power conversion means, and the input winding of the transformer is connected to the AC input of the second power conversion means. The output S line of the transformer is connected to the AC side of the forward/reverse converter, the third winding of the transformer is connected to the AC side of the forward/reverse converter, and a battery is connected to the DC side of the forward/reverse converter.

[Effect]

This invention improves the input power factor and efficiency by using a diode rectifier as the converter installed on the input side of the uninterruptible power supply, and by operating the isolation transformer at a high frequency. For this purpose, the power conversion means 211, which is equipped with a diode rectifier on the input side and outputs alternating current of the desired voltage and frequency, and the forward/reverse conversion means are combined into a three-winding transformer. In addition to connecting to each winding, a bank-up battery is connected to the DC side of the forward/reverse conversion means. By operating the transformer at the highest possible frequency in this state, the circuit is insulated, made smaller and lighter, and improved in efficiency and input power factor.

〔Example〕

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention.

In FIG. 1, a first inverter device 20 as a first power conversion means is connected to a commercial power source 2, and this first inverter device 20 receives AC power at a commercial frequency from the commercial power source 2. A diode rectifier 21 that rectifies direct current, a smoothing capacitor 22 that absorbs and removes ripples in the direct current output from the diode rectifier 21, and a transistor inverter 23 that converts this smoothed direct current into alternating current of arbitrary voltage and frequency. However, the frequency of the AC output from this transistor inverter 23 is set to be as high as possible.

The high-frequency AC power output from the first inverter W20 is applied to the input winding of the three-winding transformer 30, and is insulated from the output winding of the transformer 30 from the commercial power line 1IA2. High-frequency AC power transformed to a voltage of Therefore, a second inverter device 40 as a second power conversion means composed of a diode rectifier 41, a smoothing capacitor 42, and a transistor inverter 43 is connected to the output winding of the three-winding transformer 30, and the transistor inverter 43 is connected to the output winding of the three-winding transformer 30. With proper control,
AC power of a desired voltage and frequency can be supplied to the load 60.

Further, the AC side of a forward/reverse converter 50 is connected to the third winding of the three-winding transformer 30, and a battery lO is connected to the DC side of the forward/reverse converter 50 to be used as a backup during a power outage. Continue.

When power is normally supplied from commercial power supply 2,
Since the inverter device 20 supplies high-frequency AC power to the second inverter device 1140 via the three-winding transformer 30, the load 60 is in operation with the AC power output from the second inverter device 40. At this time, by operating the forward/inverter converter 50 for forward conversion, the power is transferred from the commercial power source 2 through the path of commercial power supply 2 -> first inverter device 20 -> 3-winding transformer 30 -> forward/inverter converter W 50 -> battery IO. The battery 10 can be charged with AC power.

The embodiment circuit shown in FIG. 1 includes a circuit (not shown) for detecting a power outage of the commercial power supply 2 and a circuit (both not shown) for causing the forward/inverter 50 to perform a forward conversion operation or an inverse conversion operation. As described above, when the commercial type a2 detects a power outage while the load 60 is operating with electric power from the commercial power source 2, the forward/inverse converter 50 immediately starts the inverse conversion operation. Battery lO → forward/reverse converter 50 → 3
Electric power is supplied through the path of the wire-wound transformer 30 → second inverter device 40 → load 60, and there is no fear that the load 60 will experience a power outage.

The frequency of the alternating current from the forward/inverter converter 50 to the three-winding transformer 30 is a high value similar to the frequency of the alternating current output from the first inverter device 20, for example, from several kHz to several tens of kHz.
& is used for conventional commercial frequencies (507~6
0 Hz), the size and weight of the three-winding transformer 30 will naturally be reduced, and the price can of course be reduced.

In the example circuit shown in FIG. 1, since the commercial power supply 2, the load 60, and the battery 10 are insulated from each other, three independent windings, that is, the input winding and the output winding. Three-winding transformer 3 with a winding and a third winding
However, if, for example, there is no need to insulate the commercial power supply 2 and the load 60 and you want to insulate only the battery IO from them, the input and output should be configured with autotransformers and In this case, it is sufficient to prepare a transformer having a configuration in which independent windings are connected to the forward/reverse converter 50, and to operate this transformer at a high frequency.

〔Effect of the invention〕

According to this invention, there are two sets of power conversion means that are equipped with diode rectification means in the input section and convert input exchange into alternating current of arbitrary voltage and frequency, and a forward/reverse converter that can convert direct current to alternating current or alternating current to direct current. An uninterruptible power supply can be created by connecting the means and means through an insulating transformer, connecting a commercial power supply to the input side, a load to the output side, and a battery to the DC side of the forward/reverse conversion means. By operating each conversion means so that the frequency of the alternating current applied to the transformer, which also serves as insulation, is as high as possible, the commercial power source, the load, and the battery are mutually isolated. At the same time, the size of the insulating transformer can be significantly reduced, contributing to the miniaturization, weight reduction, and cost reduction of the device. Furthermore, by using diode rectification means at the input section of the power conversion means, the DC output voltage is higher than that of thyristor rectification means, and since there is no phase control operation, the power factor of AC input is good, and the power It has various advantages, such as improved efficiency of the conversion means, simplified control circuit, and reduced cost.

[Brief explanation of drawings]

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention. Figure 2 is a main circuit connection diagram showing a conventional example of an uninterruptible power supply system that is said to be a floating charging system, and Figure 3 is a main circuit diagram showing a conventional example of an uninterruptible power supply system equipped with a battery charging device. It is a connection diagram. 2... Commercial power supply, 3... Transformer, 4... Thyristor rectifier, 5.21.41... Diode rectifier, 6
...Smooth reactor? , 13.22.42...
Smoothing capacitor, 8゜23.43...Transistor inverter, 10...Battery, 11...Charging transformer, 12...Charging rectifier, 14...Chinnopa,
15... Cyrisk switch, 20... First inverter device as first power conversion means, 30... Three winding transformer, 40... Second inverter device as second power conversion means , 50... Forward/inverse converter, 60... Load.

Claims (1)

[Claims] 1) A first power exchange means that is connected to an AC power source and outputs an alternating current of a predetermined voltage and frequency, and a second power exchange means that inputs the alternating current and outputs an alternating current of a desired voltage and frequency. a power conversion means;
It is equipped with a forward/reverse exchange means capable of converting alternating current to direct current or converting direct current to alternating current, an input winding, an output winding, and a third winding insulated from these input windings and output windings. a transformer; an input winding of the transformer is connected to the AC output side of the first power conversion means; an output winding of the transformer is connected to the AC input side of the second power conversion means; An uninterruptible power supply device characterized in that the third winding of the transformer is connected to the alternating current side of the converting means, and a battery is connected to the direct current side of the forward/reverse converting means. 2) The uninterruptible power supply according to claim 1, wherein the first or second power conversion means includes a rectification means using a diode at its input section. 3) An uninterruptible power supply according to claim 1 or 2, wherein the transformer is operated at a frequency as high as possible.