JP2568271B2 - DC uninterruptible power supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a DC uninterruptible power supply device, and more specifically, it uses a high power factor converter as an AC / DC conversion circuit connected to an AC power supply, and The present invention relates to a DC uninterruptible power supply device equipped with a storage battery that supplies power to a load during a power failure.

(Prior Art) FIG. 3 shows the configuration of a conventional DC uninterruptible power supply of this type. In the figure, 1 is an AC power supply, 2 is an AC reactor, 3 is a PWM rectifier, 4 is a capacitor, and in the AC reactor 2, a PWM rectifier 3 and a capacitor 4 constitute a high power factor converter. Also, the capacitor 4
The storage battery 6 is connected to one end of the battery via an anti-parallel circuit of a discharge diode 5, a charging diode 7, and a series circuit of a DC current transformer 8. In the illustrated example, one phase of the AC power supply 1 is shown, but AC / DC conversion of three phases is actually performed.

In such a configuration, when the AC power supply 1 is healthy, the voltage of the capacitor 4 connected to the DC output side is controlled while the PWM rectifier 3 is PWM-controlled so that the current of the AC reactor 2 becomes a sine wave with a power factor of 1. Is controlled to be constant and DC power is supplied to a load (not shown). That is, when the PWM rectifier 3 is turned on, energy is stored in the AC reactor 2, and when it is turned off, this energy is discharged to the capacitor 4 at a high frequency. The voltage of 4 is controlled to be constant.

At this time, the storage battery 6 is charged via the charging diode 7 and the DC current transformer 8. The DC current transformer 8 is provided to detect the charging current of the storage battery 6 and limit the current value to a predetermined value or less.

On the other hand, when a power failure occurs in the AC power supply 1, DC power is supplied from the storage battery 6 to the load via the discharge diode 5, so that the power supply device is uninterrupted.

(Problem to be Solved by the Invention) In the above-described conventional power supply device, since the DC output is obtained from the storage battery 6 via the discharge diode 5 when the AC power supply 1 fails, the voltage fluctuation of the storage battery 6 remains unchanged. There is a drawback that the DC output voltage fluctuates, and the fluctuation range becomes large. For example, when a lead storage battery is used as the storage battery 6, the voltage fluctuation range is large such that the charge state (equal voltage) is 2.3 V / cell and the end discharge state (discharge end voltage) is 1.6 V / cell. Therefore, the load that can be directly connected to the DC output terminal of the power supply is limited,
In general usage without load limitation, a silicon dropper or a chopper is connected to the DC output terminal in order to suppress the fluctuation range, which causes a problem that the power supply is large and expensive. .

Also, in an AC uninterruptible power supply (UPS) that combines this power supply and an inverter, it is necessary to use an inverter connected to the DC output terminal that can withstand a wide range of DC input voltage fluctuations. There was a problem that it became large and expensive.

The present invention has been proposed in order to solve the above problems, and an object thereof is to provide a direct-current uninterruptible power supply device that does not fluctuate in direct-current output voltage during a power failure of an alternating-current power supply and that is small and inexpensive. To provide.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a high power factor converter by supplying direct current power from a storage battery to a high power factor converter by a direct current power supply means such as a switch at the time of power failure of an alternating current power supply. It is characterized in that the rate converter operates as a boost chopper.

(Operation) According to the present invention, by supplying DC power from the storage battery to the high power factor converter to operate the high power factor converter as a step-up chopper at the time of power failure of the AC power supply, the power supply device can be operated even if the voltage of the storage battery drops. The DC output voltage of can be controlled to be constant.

Further, when the AC power supply is restored, the high power factor converter is controlled so that the AC input current becomes a sine wave with a power factor of 1, and at the same time, the DC output voltage is controlled to a constant voltage.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, and in FIG. 3, the same components are designated by the same reference numerals and the description thereof will be omitted.
Hereinafter, different parts will be mainly described.

In FIG. 1, a first switch 9 is connected between the AC power supply 1 and the AC reactor 2, and DC power is connected between the connection point of the switch 9 and the AC reactor 2 and the anode of the discharge diode 5. A second switch 10 as a supply means is connected. In addition to the charging diode 7 and the DC current transformer 8, a third switch 11 is connected in series to both ends of the discharging diode 5, and the charging diode 7, the DC current transformer 8 and the switch 11 are connected to each other. A charging circuit for the storage battery 6 is configured.

As in FIG. 3, the AC reactor 2, the PWM rectifier 3 and the capacitor 4 constitute a high power factor converter.

In such a configuration, when the AC power source 1 is sound, the switch 9 is turned on, the switch 10 is turned off, and the switch 11 is turned on, so that a circuit configuration equivalent to that shown in FIG. 3 is obtained.
Therefore, in this state, the PWM rectifier 3 is operated so that the current of the AC reactor 2 becomes a sine wave with a power factor of 1, and at the same time, the constant voltage is adjusted so that the voltage of the capacitor 4 becomes a voltage necessary for charging the storage battery 6. Take control.

Further, when the AC power supply 1 fails, the switch 9 is turned off, the switch 10 is turned on, and the switch 11 is turned off to supply the DC power of the storage battery 6 to the high power factor converter, and the PWM rectifier 3 is operated as a step-up chopper. As a result, even if the voltage of the storage battery 6 drops, the output voltage of the PWM rectifier 3, that is, the voltage of the capacitor 4 is made higher than the voltage of the storage battery 6, and control is performed so that the DC output voltage of the power supply device becomes constant.

Next, FIG. 2 shows a second embodiment of the present invention, in which the AC power supply 1'is a single phase. When a single-phase AC power source is used as described above, the high power factor converter has a rectifier 12 and a DC reactor 1 as shown in FIG.
3. The boost chopper 14 and the capacitor 4 are included, and other configurations are similar to those of the first embodiment. Therefore, the first switch 9 can be omitted as compared with the first embodiment. In addition, one end of the second switch 10 for supplying DC power from the storage battery 6 to the high power factor converter is connected to the DC output side of the rectifier 12.

In this embodiment, the constant voltage control of the capacitor 4 is performed by turning off the switch 10 and turning on the switch 11 when the AC power source 1 is healthy, and when the power failure occurs, the switch 10 is turned on and the switch 11 is turned off. As a result, even if the voltage of the storage battery 6 drops, the boost chopper 14 keeps the DC output voltage constant.

Although not shown, the present invention is also applicable to an AC uninterruptible power supply device in which an inverter as a load is connected to a DC output terminal, DC / AC conversion is performed by this inverter, and AC power is supplied to a final load. Of course, it can be applied.

(Effect of the invention) As described above, according to the present invention, when the AC power supply is interrupted, the storage battery voltage is boosted by the high power factor converter as the boost chopper to obtain the DC output.
The fluctuation range of the DC output voltage can be suppressed smaller than that of the conventional power supply device. For example, when a lead storage battery is used as the storage battery, conventionally, it varies in the range of 1.6 V / cell (during discharge) to 2.3 V / cell (during charge) as described above. Even when discharged to (1.6V / cell), the charged state voltage is 2V / cell, so the range of fluctuation is from 2V / cell (short time at power recovery) to 2.3V / cell (at charging).

As described above, in the present invention, since the fluctuation range of the DC output voltage can be suppressed to be small, it is not necessary to use a silicon dropper or a chopper as in the conventional case, and the power supply device can be downsized and low cost, and the DC output terminal can be used. In an AC uninterruptible power supply configured by connecting an inverter, a small and low-priced inverter can be used because the fluctuation of the DC input voltage of the inverter is small.

And so on.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the present invention, and FIG. 3 is a circuit diagram showing a conventional technique. 1, 1 '... AC power supply, 2 ... AC reactor 3 ... PWM rectifier, 4 ... Capacitor 5 ... Discharge diode, 6 ... Storage battery 7 ... Charging diode, 8 ... DC current transformer 9-11 ...... Switch, 12 …… Rectifier 13 …… DC reactor, 14 …… Boost chopper

Claims (1)

(57) [Claims] 1. A high power factor converter which is connected to an alternating current power source and which converts alternating current power into direct current power and supplies the load while converting an alternating current input current into a sine wave of high power factor by a switching operation, and a converter of this converter. In a DC uninterruptible power supply device that is connected to a DC output side and is normally charged, and includes a storage battery that supplies power to a load when the AC power supply fails, when the AC power supply fails, DC power is supplied from the storage battery to the converter. A DC uninterruptible power supply, characterized in that it is provided with a DC power supply means for supplying, and the converter is operated as a step-up chopper at the time of the power failure.