JP2589799Y2 - Uninterruptible power system - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention is used, for example, as a power source for a computer. When commercial AC power is being received, the commercial AC power is supplied to a load, and when the commercial AC power is cut off, the power of a built-in storage battery is used. And to a standby type uninterruptible power supply which supplies the load to the load after converting the power into an alternating power by an inverter, particularly in order to prevent a large inrush current from being generated when switching to the output of the inverter.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional uninterruptible power supply. One end of each of the electric wires 11 and 12 is connected to both ends of the commercial power supply 13, the other end is connected to each fixed contact a of the changeover switches 14 and 15, and each movable contact of the changeover switches 14 and 15 is connected to both ends of the load 16. Connected. A storage battery 18 is connected to the electric wires 11 and 12 through a charging circuit 17.
Is connected to the input side of the inverter 19,
Are connected to the fixed contacts b of the changeover switches 14 and 15, respectively. A power failure detection circuit 22 is connected to the electric wires 11 and 12 via a transformer 21, and a synchronization circuit 23 is connected. The output of the synchronization circuit 23 is the inverter 1
9.

[0003] While normal commercial AC power is supplied from the commercial power supply 13, the commercial AC power is supplied to the load 16. When the commercial AC voltage falls to a certain value, for example, 80 V or less, this is detected by the power failure detection circuit 22, and the detected output activates the inverter 19, which operates in synchronization with the commercial AC voltage before the power failure and detects the power failure. The switches 14 and 15 are switched to the fixed contact b side by the output, and the square wave power having a peak value of 140 V, for example, is supplied from the inverter 19 to the load 16.

[0004]

When the commercial power supply 13 is out of power, the commercial AC voltage immediately before it is often unstable, and when switching to the output of the inverter, a large inrush current may flow to the load. is there. For example, as shown in FIG. 4A, it is detected that the commercial AC voltage has dropped relatively slowly and a power failure has occurred, and the inverter 1 is switched to the commercial AC voltage.
When the output of _No. 9 is supplied to the load 16, as shown in FIG. 4B, the voltage of the power supplied to the load 16 decreases, and a half-wave of the commercial AC voltage having a peak value of V ₁ is supplied to the load 16. Then, a square wave voltage having the rated peak value V ₂ is supplied from the inverter 19 to the load 16, and before and after the switching, the voltage supplied to the load 16 and its peak value greatly change.

In particular, when the load 16 is a rectifier of the capacitor input type, the charging energy of the capacitor is CV ₁ ² /
From ^_2, CV 2 2/2 becomes the difference is large, a large rush current 24 to the current flowing into the capacitor input type load, as shown in FIG. 4C is generated. Due to such an inrush current, stress is applied to the input fuse and the rectifying power element of the load 16, and there is a disadvantage that deterioration is promoted.

[0006] Similarly if the transformer or to the input side of the load 16 is connected, occur asymmetric magnetization by the voltage difference between V ₁ and V ₂ at the time of switching, the inrush current in the worst case the transformer is saturated And the same problem occurs. In particular, when the output waveform of the inverter 19 is a square wave, the change in the peak value at the time of switching becomes sharper, and in the case of a capacitor input type load, a larger inrush current is generated.

[0007]

In order to achieve the above object, uninterruptible power due to this invention
The source device generates a DC voltage proportional to the peak value of the commercial AC power.
A peak value detecting means for detecting, and a control terminal for controlling the power of the built-in storage battery.
Converted to the voltage according to the input voltage of the slave and supplied to the inverter
Voltage conversion means, reference voltage generation means, and capacitor
And the charging voltage of the capacitor and the output voltage of the voltage conversion means.
To the control terminal of the voltage conversion means.
The error amplifier to be supplied and the power failure detection means
In the condition where the DC voltage detected by the peak value detection means
When the power failure detection means detects a power failure, the reference
Capacitor through resistance element with reference voltage of pressure generation means
Switching means for charging is provided .

[0008]

FIG. 1 shows an embodiment of the present invention, in which parts corresponding to those in FIG. 3 are denoted by the same reference numerals. In this example, a full-wave rectifier circuit 25 is connected to the secondary side of the transformer 21, one end of the output side of the full-wave rectifier circuit 25 is grounded, and the other end is connected to a resistor 26.
Through the analog switch 27 and to one end of a capacitor 28, the other end of the capacitor 28 is grounded, and a resistor 29 is connected in parallel with the capacitor 28.
Therefore, when the switch 27 is turned on, the output of the transformer 21 is rectified and smoothed by the resistor 26 and the capacitor 28.
A voltage V ₁ almost proportional to the peak value of the commercial AC voltage is always obtained between both ends of the capacitor 28.

The input voltage of the inverter 19 is equal to this voltage V ₁
Is always followed. That is, the output of the storage battery 18 is converted by the voltage conversion means 31 so as to be equal to the peak value of the commercial AC voltage, and is supplied to the inverter 19. As the voltage conversion means 31, for example, a DC / DC converter is used, and the output voltage V _DC of the DC / DC converter 31 is used.
Is supplied to the inverting input side of the error amplifier 32, and the voltage across the capacitor 28 is supplied to the non-inverting input side of the error amplifier 32 through the backflow prevention diode 33. The non-inverting input side is grounded through a resistor 34, and the output of the error amplifier 32 is supplied to the DC / DC converter 31 as an output voltage control signal. Thus, the output voltage of the DC / DC converter 31 becomes almost equal to the peak value of the input commercial AC voltage at that time.

The connection point between the switch 27 and the capacitor 28 is connected to a reference power supply 37 through an analog switch 35 and further through a resistor 36. Switch 27 in the power failure detection signal V _D is turned off, the switch 35 is turned on.
Input commercial AC voltage V _in is relatively slow decrease as shown in FIG. 2A, the capacitor 28 as shown in Figure 2B,
Ho to the peak value of the input commercial AC voltage V _in Isuzu signal proportional to V ₁
Is obtained, which is also decreased with time, the output voltage V _DC of the DC / DC converter 31 to follow the signal V ₁ is 2
It changes as shown in D. Input commercial AC voltage V _in is constant reference voltage, for example, drops below 80V (rms), generated power failure signal V _D to the time t _2, switch 2
7 is turned off, the switch 35 is turned on, and the reference voltage V _S from the reference power source 37 starts charging the capacitor 28 through the resistor 36, and the voltage of the capacitor 28 gradually increases from V ₁ to V _S. Time t ₂ as the output voltage V _DC of the DC / DC converter 31 is shown in FIG. 2D along with this
Gradually increase from. The inverter 19 is in a cold stand-by during the commercial power supply voltage receiving in synchronism with this, is activated by a power failure signal V _D, for example, it outputs a rectangular alternating voltage distribution angle [pi / 2 (constant). The switches 14 and 15 are connected to the fixed contact b side. Accordingly, as shown in FIG. 2E, the alternating voltage Vout supplied to the load 16 decreases as the commercial AC voltage decreases, and by switching to the inverter output, the alternating voltage having the same peak value as the reduced commercial AC voltage gradually decreases. growing. When this alternating voltage is Teikakuha high, the output voltage V _DC of the DC / DC converter 31 becomes equal to the reference voltage V _S, it is held in this state.

According to this invention, since the load 16 operates as described above, even if the load 16 is a capacitor input type, the charge to the input capacitor does not suddenly increase when the output is switched to the inverter output. There is no danger of current generation. Assuming that the square wave output of the inverter output has a flow angle of π / 2 as described above, the sine wave voltage of the commercial power supply has the same effective value at the same crest value, and the crest value and the effective value are made to coincide with each other. Output can be switched.

[0012] commercial AC voltage in the embodiment of FIG. 1 is equal to or less than a predetermined value, the voltage E ₁ from the power source 39 is supplied to the non-inverting input of the error amplifier 32 through the blocking diode 41, the voltage applied thereto For example, the commercial AC voltage is prevented from dropping below 90 V and the peak value 126 V or below, and the output amplitude of the inverter 19 is not delayed so much that it becomes rated. Further, in this example, when the peak value V ₁ becomes higher than a predetermined value, the reverse current blocking diode 42 conducts, a current flows toward the power supply 43, and the voltage on the non-inverting input side of the error amplifier 32 becomes E ₂ or more. For example, it is limited so that the commercial AC voltage does not exceed a peak value of 184 V at 110 V. By doing so, the commercial AC voltage exceeds the range of 100 ± 10V,
In addition, when a power failure occurs, the output is switched to the output of the inverter 19 in accordance with the peak value on the side closer to 90 V or 110 V, and the difference between the peak values is always small with respect to the fluctuation of the commercial AC voltage during receiving power. Can be.

[0013]

As described above, according to the present invention, at the time of a power failure, an inverter output having a peak value almost equal to the peak value of the commercial AC voltage immediately before the power supply is supplied to the load, and the inverter output is gradually reduced. Since the rated value is increased, even when a capacitor input type rectifier circuit represented by a switching regulator is used as a load, when switching from commercial AC voltage to inverter output voltage, the inrush current of the capacitor charging due to the voltage difference is reduced. This can be suppressed.

Therefore, the deterioration of the fuse and the rectifier on the load side is reduced. It is possible to provide an uninterruptible power supply with low cost and excellent load adaptability, which can prevent the output voltage from abnormally lowering due to the inverter overload protection operation at the time of switching, can design the allowable peak current of the inverter to be small. it can.

[Brief description of the drawings]

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

FIG. 2 is a waveform diagram for explaining FIG. 1;

FIG. 3 is a connection diagram showing a conventional uninterruptible power supply.

FIG. 4 is a waveform chart for explaining a problem of the apparatus of FIG. 3;

Claims (1)

(57) [Scope of request for utility model registration] When the commercial AC power is supplied to a load while the commercial AC power is being received, and a decrease in the commercial AC voltage is detected by a power failure detecting means, the power of the built-in storage battery is replaced by an inverter instead of the commercial AC power. The uninterruptible power supply that converts the power into alternating power and supplies the power to the load detects a DC voltage that is proportional to the peak value of the commercial AC power.
Peak value detecting means and the power of the built-in storage battery
To a voltage corresponding to the input voltage of the
, A reference voltage generator, a capacitor, a charging voltage of the capacitor, and an output of the voltage converter.
Detecting an error voltage with respect to the voltage, and
The error amplifier to be supplied to the control terminal and the power failure detection means in a state where the power failure has not been detected,
Charges the above capacitor with the DC voltage detected by the peak value detection means
When the power failure detection means detects a power failure,
With the reference voltage of the voltage generation means,
An uninterruptible power supply , comprising: switching means for charging the battery .