JPH07298516A - Uninterruptible power supply - Google Patents

Abstract

PURPOSE:To reduce the size and weight by stepping down the DC voltage from an AC/DC converter circuit and charging a battery at the time of receiving power whereas boosting the DC voltage of the battery and applying the boosted voltage to a DC/AC converter circuit at the time of power interruption. CONSTITUTION:The uninterruptible power supply comprises an AC/DC converter circuit 2 for converting AC power from a commercial power supply 1 into DC power, a DC/AC converter circuit 3 for converting DC power into AC power, a battery 7, and a bidirectional chopper circuit 9 connected between the battery 7 and the joint of the converters 2, 3. When power is received from the commercial power supply 1, DC power from the AC/DC converter circuit 2 is stepped down to an appropriate level through the bidirectional chopper circuit 9 in order to charge the battery 7. When power supply is interrupted, DC voltage of the battery 7 is boosted through the chopper circuit 9 and applied to the DC/AC inverter circuit 3. Since the bidirectional chopper circuit can be used commonly, the uninterruptible power supply can be reduced in size and weight.

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, and more particularly, to a reduction in size and weight of an uninterruptible power supply used as a backup power supply for computers and communication equipment.

[0002]

2. Description of the Related Art As shown in the block diagram of FIG. 3, an uninterruptible power supply always supplies AC power from a commercial power supply 1 to AC power.
/ DC converter circuit 2 and DC / AC inverter circuit 3
Is supplied to the load 4 such as a computer or a communication device via the step-up chopper circuit 5 and the storage battery 7 is charged via the step-down chopper circuit 5, and the DC voltage of the storage battery 7 is boosted during the power failure.
The DC power is boosted to supply the DC power to the DC / AC inverter circuit 3, which is converted to AC power by the DC / AC inverter circuit 3 and supplied to the load 4.
Reference numeral 8 denotes the AC / DC converter circuit 2 and DC / A
A capacitor inserted between the C inverter circuit 3 and the C inverter circuit 3.

According to the uninterruptible power supply of FIG. 3, the storage battery 7
Is charged through the step-down chopper circuit 5, and the DC voltage thereof is boosted by the step-up chopper circuit 6, so that the number of cells of the storage battery 7 can be reduced and the uninterruptible power supply can be reduced in size and weight.

As the step-down chopper circuit 5 and the step-up chopper circuit 6 in the above-mentioned uninterruptible power supply, those shown in FIG. 4 are used.

That is, in FIG. 4, the step-down chopper circuit 5 comprises a series circuit of a transistor 51 and a diode 52, and a choke coil 53 connected to a series connection point of the transistor 51 and the diode 52. The step-down chopper circuit 6 is connected to the series circuit of the diode 61 and the transistor 62, and the series connection point of the diode 61 and the transistor 62. A choke coil 63 is used to store energy in the choke coil 63 when the transistor 62 is turned on, and transfer the energy stored when the transistor 62 is turned off to the capacitor 8 via the diode 61 to obtain a boosted DC voltage. It is a thing.

[0006]

In the uninterruptible power supply device described above, the capacity of the step-up chopper circuit 6 is limited by the load 4, so the charging time of the storage battery 7 is lengthened and the capacity of the step-down chopper circuit 5 is reduced. By doing so, it is possible to reduce the size and weight of the uninterruptible power supply, but when it is necessary to shorten the charging time of the storage battery 7, the transistor 51, the diode 52, and the diode 52 of the step-down chopper circuit 5 are accordingly changed. The choke coil 53 must be increased in size, which is not preferable in reducing the size and weight of the uninterruptible power supply.

[0007]

In order to solve the above problems, the present invention provides an AC / DC converter circuit for converting AC power from a commercial power source into DC power, and DC power from the AC / DC converter circuit. DC to convert to AC power
A / AC inverter circuit, a storage battery, and a connection point between the AC / DC converter circuit and the DC / AC inverter circuit and the storage battery, which is A when receiving commercial power.
A bidirectional chopper circuit for stepping down the DC power from the C / DC converter circuit to charge the storage battery, and stepping up the DC voltage of the storage battery and applying it to the DC / AC inverter circuit when the commercial power supply fails. It is characterized by having.

[0008]

Therefore, the uninterruptible power supply of the present invention charges the storage battery by reducing the DC power from the AC / DC converter circuit to an appropriate DC voltage when the commercial power is received, and the storage battery when the commercial power fails. DC voltage of the
Since the bidirectional chopper circuit for applying to the C / AC inverter circuit is provided, one choke coil can be commonly used for step-up / down.

[0009]

1 is a block diagram of an uninterruptible power supply according to the present invention, in which parts having the same functions as those in FIG. 3 are designated by the same reference numerals.

FIG. 2 is a circuit diagram of a bidirectional chopper circuit used in the uninterruptible power supply system of the present invention, and parts having the same functions as those in FIG. 4 are described in correspondence with each other.

The feature of the present invention is, as shown in FIG. 1, an AC / D for converting AC power from the commercial power source 1 into DC power.
A C converter circuit 2, a DC / AC inverter circuit 3 for converting DC power from the AC / DC converter circuit 2 into AC power, a storage battery 7, the AC / DC converter circuit 2 and the DC / AC inverter circuit 3. The bidirectional chopper circuit 9 is provided with the bidirectional chopper circuit 9 connected between the connection point of the battery and the storage battery 7. The voltage of the storage battery 7 is charged by stepping it down to an appropriate DC voltage, and when the commercial power source 1 fails, the DC voltage of the storage battery 7 is boosted by the bidirectional chopper circuit 9 to apply the DC power to the DC / AC inverter circuit 3. It is the one.

The bidirectional chopper circuit 9 has a first switching element 9 in which a first diode 91 is connected in antiparallel.
It is inserted between the series circuit of the second switching element 94 in which 2 and the second diode 93 are connected in antiparallel, the first switching element 92, the second switching element 94, the series connection point, and the storage battery 7. When the commercial power source 1 receives power, the first switching element 92 and the second diode 93 are operated to charge the storage battery 7, and when the commercial power source 1 fails, the first diode 91 and the second diode 93 are charged. The two switching elements 94 are operated to boost the DC voltage of the storage battery 7.

That is, the first switching element 92
The second diode 93 and the step-down chopper circuit 5 of FIG.
Corresponding to the transistor 51 and the diode 52, and the first diode 91 and the second switching element 94 are
4 corresponds to the diode 61 and the transistor 62 of the boost chopper circuit 6 of FIG.
Of the choke coils 53 and 63.

Next, the operation of the bidirectional chopper circuit 9 will be described.

That is, when the commercial power source 1 is receiving power, the first switching element 92 is turned on to turn on the choke coil 9.
5, the first switching element 92 is turned off and the energy of the choke coil 95 is transferred to the storage battery 7 via the second diode 93 to charge the storage battery 7.

On the other hand, when the commercial power source 1 fails, the second switching element 94 is turned on to store energy in the choke coil 95, and then the second switching element 9 is turned on.
4 to turn off the choke coil 95 energy first
By transferring to the capacitor 8 via the diode 91, the DC voltage of the storage battery 7 is boosted.

In the above embodiment, the first switching element 9
2. A bipolar transistor is used as the second switching element 94.
ET and IGBT can also be used.

Further, although the uninterruptible power supply system in the above-mentioned embodiment is the continuous inverter power supply system without the commercial bypass line, it is the continuous inverter power supply system with the commercial bypass line or the continuous commercial power supply system. But it goes without saying that it can be used.

[0019]

As described above, according to the present invention, the choke coil of the bidirectional chopper circuit can be shared, and the uninterruptible power supply can be reduced in size and weight.

Further, according to the present invention, the first switching element having the first diode connected in anti-parallel and the second switching element having the second diode connected in anti-parallel can be configured as one module. Therefore, the number of parts of the uninterruptible power supply can be reduced and the reliability can be improved.

Further, according to the present invention, since the capacity of the choke coil is designed by the capacity of the uninterruptible power supply, the storage battery can be charged with the charging capacity within the allowable capacity, thereby allowing the allowable capacity of the choke coil. The charging time of the storage battery can be easily changed within.

[Brief description of drawings]

FIG. 1 is a block diagram of an uninterruptible power supply device of the present invention.

FIG. 2 is a circuit diagram of a bidirectional chopper circuit used in the uninterruptible power supply device of the invention.

FIG. 3 is a block diagram of a conventional uninterruptible power supply.

FIG. 4 is a circuit diagram of a step-down chopper circuit and a step-up chopper circuit used in a conventional uninterruptible power supply.

[Explanation of symbols]

 1 Commercial Power Supply 2 AC / DC Converter Circuit 3 DC / AC Inverter Circuit 4 Load 5 Step-Down Chopper Circuit 6 Boost Chopper Circuit 7 Storage Battery 8 Capacitor 9 Bidirectional Chopper Circuit

Claims (2)

[Claims] 1. An AC / DC converter circuit for converting AC power from a commercial power source into DC power, and a DC for converting DC power from the AC / DC converter circuit into AC power.
A / AC inverter circuit, a storage battery, and a connection point between the AC / DC converter circuit and the DC / AC inverter circuit and the storage battery, which is A when receiving commercial power.
A bidirectional chopper circuit for stepping down the DC power from the C / DC converter circuit to charge the storage battery, and boosting the DC voltage of the storage battery to apply it to the DC / AC inverter circuit when the commercial power source fails. An uninterruptible power supply characterized by being equipped. 2. The uninterruptible power supply device according to claim 1, wherein the bidirectional chopper circuit includes a first switching element having a first diode connected in anti-parallel and a second switching element having a second diode connected in anti-parallel. An uninterruptible power supply comprising: a series circuit with an element; and a choke coil inserted between a series connection point of the first switching element and the second switching element and a storage battery.