JPH0946931A - Uninterruptible power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress voltage ripples by stopping a capacitor which applies voltage through a resistor with the detection of recovery voltage of a commercial power source, and stopping the second DC-DC converter gradually, according to the terminal voltage of the capacitor. SOLUTION: When commercial power recovers from power failure, a photodiode 6 is turned on. Therefore, a capacitor(CS) C1 is charged through a resistor R1. The terminal voltage of CSC1 is added to CSC2 and the base of a transistor(Tr) 4 through a resistor 3 and a diode D2. Raising the terminal voltage of CSC2 will turn on Tr4 and turn off SW2 with the timing of shortening the ON period of a switching element(SW) 2. By the terminal voltage of the CSC2 going up according to the time constants of R1.C1, the timing of turning off of SW2 becomes quick, and if it goes up furthers, SW2 continues OFF condition.

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 device capable of supplying power to a load even when a commercial power supply fails. The commercial power supply may lose power due to a failure of the power plant, substation, power transmission line, distribution line, etc. Therefore, an uninterruptible power supply device is provided for the device that cannot stop the operation, and the commercial power supply fails. At times, a configuration is adopted in which power is supplied from an uninterruptible power supply. There is a demand for stable operation of such an uninterruptible power supply.

[0002]

2. Description of the Related Art An uninterruptible power supply system has a basic structure in which an AC voltage of a commercial power supply is rectified to supply a stabilized DC voltage to a load, and a battery supplies power to the load during a power failure. In that case, the battery is charged from the commercial power source via the DC-DC converter, and the DC-D is supplied from this battery.
A configuration is known in which power is supplied to the load via the C converter, and when the commercial power supply fails, it is possible to supply power to the load from the constantly charged battery via the DC-DC converter. However, the DC-
Since two DC converters are connected in cascade,
The overall efficiency is represented by the product of the efficiencies of each DC-DC converter, and thus there is a problem of low efficiency.

Therefore, as shown in FIG.
From the load 56 via the first DC-DC converter 53
Power is supplied to the load 56, and the commercial power supply 51 is monitored by the monitoring circuit 55. When a power failure occurs, the power cannot be supplied from the first DC-DC converter 53 to the load 56. Therefore, the second DC-DC converter 54 is operated and the battery 52 To the second DC
A configuration is adopted in which power is supplied to the load 56 via the DC converter 54. In this case, since only one DC-DC converter operates to supply power to the load 56 from the commercial power supply 51 or the battery 52, the overall efficiency is
It is the efficiency of each DC-DC converter.

FIG. 8 is an explanatory view of a main part of a conventional RCC type converter, which corresponds to a main part when the second DC-DC converter 54 in FIG. 7 is a ringing choke converter (RCC) type. To do. In the figure, 61 is a transformer, 61a is a primary winding, 61b is a secondary winding, and 61c.
Is a tertiary winding, 62 is a switching element, 63 is a control circuit, 64 and 67 are control transistors, 65 and 66 are phototransistors, R12, R14 and R15 are resistors, and C.
12, C13 are capacitors, and D11 is a diode. The soft start circuit and the like are not shown.

The commercial power supply 51 is monitored by the monitoring circuit 55 shown in FIG. 7, and the drive current of the phototransistor 66 and the photodiode (not shown) forming the photocoupler shown in FIG. A drive current is supplied to the switching element 62. Also, the output DC voltage of the rectifying / smoothing circuit (not shown) connected to the secondary winding 61a of the transformer 61 is monitored, and the photodiode (not shown) is controlled by the error corresponding to the difference from the reference voltage, The phototransistor 65 forming the photo diode and the photo coupler is controlled.

Therefore, the monitoring circuit 55 causes the commercial power source 51 to operate.
When the power recovery is detected, the phototransistor 66 is turned on, the control transistor 67 is turned on, and the switching element 62 is turned off. That is, the operation of the second DC-DC converter 54 is stopped, and the commercial power source 5
1 to the load 5 via the first DC-DC converter 53
Power to 6.

When the power failure of the commercial power supply 51 is detected, the phototransistor 66 is turned off and the control transistor 67 is also turned off. Therefore, the switching element 62 is
When the voltage is turned on according to the induced voltage of the tertiary winding 61c of the transformer 61 and the terminal voltage of the capacitor C12 reaches a set value, the control transistor 64 is turned on and the switching element 62 is turned off. Capacitor C12 in that case
Since the rise in the terminal voltage of the switching element 62 can be controlled by controlling the current flowing through the phototransistor 65, the ON period of the switching element 62 can be controlled. That is, the output DC voltage can be stabilized.

FIG. 9 is an explanatory view of a main part of a conventional pulse width control type converter, which corresponds to a main part of the second DC-DC converter 54 in FIG. In the figure, 71 is a comparison circuit, 72 is an oscillator that outputs a triangular wave signal, 73 is a phototransistor, 74 is a control transistor, and R2.
1 to R25 are resistors, and C21 is a capacitor. Illustration of a transformer, a switching element, a rectifying / smoothing circuit on the secondary side, etc. is omitted.

The comparison circuit 71 has a triangular wave signal TS from an oscillator 72, a difference EV between an output DC voltage and a reference voltage,
The dead time signal DT is compared and the switching element connected to the primary winding of the transformer (not shown) is driven. Further, the phototransistor 73 is the monitoring circuit 55 (see FIG.
The phototransistor 73 and the control transistor 74 are turned off when the commercial power supply 51 detects a power failure. As a result, the dead time signal DT input to the comparison circuit 71 becomes a divided voltage by the resistors R24 and R25, and is selected as a value smaller than the normal difference signal EV. Therefore, the comparison circuit 71 outputs a difference from the triangular wave signal TS. A drive signal as a result of comparison with the signal EV is output, and the ON period of a switching element (not shown) is controlled to stabilize the output DC voltage. That is, the second DC-DC converter 54 operates to supply power to the load 56.

When the monitoring circuit 55 detects the power recovery of the commercial power supply 51, the phototransistor 73 is turned on and the control transistor 74 is also turned on. Therefore, the resistor R24 is in a state where the control transistor 74 and the resistor R23 are connected in parallel, and the dead time signal DT is set to, for example, the level of the triangular wave signal TS or more. As a result, the drive signal from the comparison circuit 71 is stopped and the switching element (not shown) is turned off. That is,
The first DC-DC converter 53 operates to supply power to the load 56.

[0011]

The first and second DC-DC converters 53 and 54 which form the uninterruptible power supply device,
One of them operates and the other stops, and when the commercial power supply 51 is normal, the first DC-DC converter 5
3 operates, the second DC-DC converter 54 stops, and the commercial power supply 51 loses power, the first DC-DC converter 53 stops and the second DC-DC converter 5
4 operates using the battery 52 as a power source. There is a problem that a large fluctuation in the output DC voltage occurs when switching between such operation start and operation stop.

That is, in the operation explanatory view of the conventional example of FIG. 10, when the first and second DC-DC converters are ringing choke converter types, (a) shows the commercial power supply 5
1 AC voltage, (b) is the first DC-DC converter 5
Output voltage V1 and output current I1, (c) of the second DC
The output voltage V2 and the output current I2 of the DC converter 54,
(D) shows the output DC voltage V3. When the commercial power supply 51 fails at time t1, a power failure detection signal is output from the monitoring circuit 55 at time t2, the phototransistor 66 (see FIG. 8) is turned off, and the soft start circuit is turned on. Second by etc.
The DC-DC converter of 1 starts operation. Therefore,
As shown in (c), the output voltage V2 rises, and the output current I2 indicated by the thick line accordingly rises. Also the first DC
The output voltage V1 of the DC converter 53 is maintained for a while by an input capacitor or the like, but gradually decreases. The output current I1 indicated by the thick line is also the second DC-DC converter 54.
Output current I2 rises and decreases.

Next, when the commercial power supply 51 recovers at time t3, the first DC-DC converter 53 starts its operation,
The output voltage V1 gradually rises, and the output current I1 also rises. Correspondingly, the output current I2 of the second DC-DC converter 54 decreases. Then, when the power recovery detection signal is output from the monitoring circuit 55 at time t4 and the phototransistor 66 (see FIG. 8) is turned on, the control transistor 67 is also turned on and the switching element 62 is turned off. That is, the operation of the second DC-DC converter 54 is stopped, and as shown in (c), the output voltage V2 drops to 0V, and at the same time, the output current I2 also drops to 0A.

When the output current I1 of the first DC-DC converter 53 changes as shown by the dotted line (b), the output current I2 of the second DC-DC converter 54 is (c).
Changes as indicated by the dotted line. Therefore, at time t4, the operation of the second DC-DC converter 54 is stopped, and the first DC-DC converter 53 shares the load, so that the output DC voltage V3 is changed as shown in (d). ΔV1
Or, it decreases by ΔV2. In particular, when the output current changes indicated by the dotted lines in (b) and (c) occur, the load is abruptly shared by the first DC-DC converter 53, so that the DC output voltage V3 becomes equal to ΔV2 of the dotted line. There is a problem of large fluctuations.

FIG. 11 is a diagram for explaining the operation of the conventional example. In the case where the first and second DC-DC converters 53 and 54 are pulse width control type converters, (a) is a comparison circuit 71. (See FIG. 9) shows the triangular wave signal TS, the difference signal EV, and the dead time signal DT input to it, (b) shows the drive signal from the comparison circuit 71, and (c) shows the output DC voltage V3. If the monitoring circuit 55 detects the restoration of the commercial power supply 51 at time t0, the phototransistor 73 (see FIG. 9) is turned on and the control transistor 74 is turned on. Therefore, the dead time signal DT is a triangular wave signal. It rises above TS, and the drive signal from the comparison circuit 71 becomes zero. That is, the second DC-DC converter 54 stops operating. As a result, the first DC-DC converter 53 suddenly shares the load, and as shown in (c), the output DC voltage V3 has a problem that it greatly fluctuates as ΔV3. The present invention relates to the first and second DC-
An object of the present invention is to suppress the fluctuation of the output DC voltage even at the time of switching the operation of the DC converter.

[0016]

The uninterruptible power supply of the present invention will be described with reference to FIG. 1. (1) A first DC-DC converter that operates using a commercial power source as a power source, and a battery as a power source. In an uninterruptible power supply device that switches a second DC-DC converter that operates and a detection signal that detects a power failure or power recovery of a commercial power supply to supply power to a load, the second DC-DC converter is a commercial power supply. A capacitor C1 which applies a voltage via a resistor R1 by detection of power recovery of
According to the terminal voltage of this capacitor C1, the second DC-D
The control circuit 3 has a configuration for gradually stopping the operation of the C converter.

(2) Also, the capacitor C1 can be charged from the constant voltage source through the resistor R1 by detecting the restoration of the commercial power source.

(3) Further, the capacitor C1 can be charged from the constant current source through the resistor R1 by detecting the restoration of the commercial power source.

(4) The second DC-DC converter has a switching element 2 connected to the primary winding 1a of the ringing choke converter type transformer 1, and controls the on / off cycle of the switching element 2. Control transistor 4, a capacitor C1 that applies a voltage through a resistor R1 upon detection of power recovery from a commercial power source, and a terminal voltage of this capacitor C1 is added to the control transistor 4 to turn on / off the switching element 2. And a control circuit 3 including a circuit for gradually shortening and shifting to OFF state.

(5) The second DC-DC converter has a switching element connected to the primary winding of a pulse width control type transformer, and the voltage is passed through a resistor by detecting the restoration of the commercial power source. It is provided with a capacitor to be added and a pulse width control circuit to add the terminal voltage of this capacitor as a dead time signal.

[0021]

[Action]

(1) When the commercial power supply recovers from the power failure state and enters the power recovery state, the first DC-DC converter automatically starts its operation. Further, due to the detection of power recovery, the second DC-DC converter gradually increases the terminal voltage of the capacitor C1 according to the time constant of the resistor R1 and the capacitor C1, so that the second voltage gradually increases in response to the increase of the terminal voltage. The operation of the DC-DC converter is stopped. Thereby, the first DC-D
The load sharing of the C converter will gradually shift, and the output DC voltage will not drop.

(2) When the capacitor C1 is charged, the rise of the terminal voltage of the capacitor C1 is controlled according to a desired characteristic by charging the constant voltage source through the resistor R1. You can
Therefore, the second DC-DC converter can be gradually stopped according to the rising characteristic of the terminal voltage of the capacitor C1.

(3) Further, by charging the capacitor C1 from the constant current source through the resistor R1, the terminal voltage of the capacitor C1 rises substantially linearly. Therefore, the second DC-DC converter can be gradually stopped according to the rising characteristic of the terminal voltage of the capacitor C1 regardless of the battery voltage.

(4) When the second DC-DC converter is a ringing choke converter type, the switching element 2 can be turned off by turning on the control transistor 4. Therefore, when the charging time constant of the capacitor C2 is controlled by the phototransistor 5, the timing at which the control transistor 4 is turned on can be controlled. Therefore, the ON period of the switching element 2 can be controlled. Further, when the phototransistor 6 is turned on by the detection of the restoration of the commercial power source, the capacitor C is connected via the resistor R1.
1 is charged, and this charging voltage causes resistance R3 and diode D
2 through the capacitor C2 and the control transistor 4
Is added to the base of the capacitor C1, the timing of turning on the control transistor 4 is sequentially increased as the terminal voltage rises according to the charging time constant of the capacitor C1, and finally turned on continuously, whereby the switching element 2 is turned on. As off
The operation of the second DC-DC converter is stopped.

(5) When the second DC-DC converter is of the pulse width control type, the pulse width control circuit compares the difference between the output DC voltage and the reference value with the triangular wave signal to detect the switching element. It controls the ON period, and in that case, a dead time signal for maintaining a predetermined OFF period is set. This dead time signal is gradually increased according to the time constant of the resistor and the capacitor by the detection of the recovery of the commercial power source, the off period is gradually increased, and the second D
The operation of the C-DC converter is stopped.

[0026]

1 is an explanatory view of a first embodiment of the present invention, in which 1 is a transformer, 1a is a primary winding, 1b is a secondary winding,
1c is a tertiary winding, 2 is a switching element, 3 is a control circuit, 4 is a control transistor, 5 and 6 are phototransistors, R1 to R5 are resistors, C1 to C4 are capacitors, and D.
1 to D3 are diodes. This embodiment corresponds to the second DC-DC converter 54 (see FIG. 7) of the ringing choke converter type. Therefore, the battery 5
2 to the primary winding 1a of the transformer 1 and the switching element 2
A DC voltage is applied to and. This switching element 2
Are shown as field effect transistors, but bipolar transistors or the like can also be used. It is also possible to replace the phototransistors 5 and 6 with a structure using a photodiode or a coupling transformer.

When the photodiode 6 is off (commercial power source is out of power), the switching element 2 is repeatedly turned on and off, whereby the second DC-DC converter is put into operation and the battery (not shown). When a load (not shown) is supplied to the load (not shown) as a power source, the output DC voltage is applied to the load (through a rectifying / smoothing circuit including a diode D3 and a capacitor C4 connected to the secondary winding 1b of the transformer 1). (Not shown), and the phototransistor 5 is controlled so that the output DC voltage becomes a set value.

When the phototransistor 5 is off,
The induced voltage in the tertiary winding 1c is the resistance R5 and the capacitor C3.
Is added to the gate of the switching element 2 via and, and the switching element 2 is turned on. Also, when it is applied to the capacitor C2 via the resistor R4 and the terminal voltage of the capacitor C2 rises, the control transistor 4 turns on,
The switching element 2 is turned off. When the phototransistor 5 is turned on, a current flows through the phototransistor 5 to the capacitor C2.
2, the charging time is faster, the terminal voltage rises faster,
The control transistor 4 turns on faster than if the phototransistor 5 is off. That is, the ON period of the switching element 2 can be shortened.

When the commercial power supply recovers from the power failure, the photodiode of the monitoring circuit (not shown) emits light in response to the recovery detection signal, and the photodiode 6 is turned on. As a result, the capacitor C1 is charged via the resistor R1. The terminal voltage of the capacitor C1 is applied to the capacitor C2 and the base of the control transistor 4 via the resistor R3 and the diode D2. Raising the terminal voltage of the capacitor C2 turns on the control transistor 4 and turns off the switching element 2 at the timing of shortening the on period of the switching element 2. Then, the terminal voltage of the capacitor C2 rises according to the time constant of R1 and C1 to accelerate the turn-off timing of the switching element 2, and when it rises further, the switching element 2 is kept in the off state.

FIG. 2 is a diagram for explaining the operation of the first embodiment of the present invention. (A) is the terminal voltage of the capacitor C2, (b) is the operation of the control transistor 4, and (c) is the switching element 2. Operation, (d) shows the terminal voltage of the capacitor C1. When the terminal voltage of the capacitor C2 rises to the threshold voltage Vth when the second DC-DC converter is in the operating state due to the power failure of the commercial power supply, the control transistor 4 is turned on as shown in (b), whereby the capacitor C2 is turned on. Is discharged and the terminal voltage drops.

Further, as shown in (c), the switching element 2 is turned on when the charging of the capacitor C2 is started by the rise of the induced voltage of the tertiary winding 1c of the transformer 1, and is turned off when the control transistor 4 is turned on. Becomes Therefore, when the terminal voltage of the capacitor C changes as shown by the solid line in (a), the control transistor 4 is turned on as shown by the solid line in (b), and the switching element 2 becomes (c).
Repeat on and off as shown by the solid line.

When the commercial power source is restored, the phototransistor 6 is turned on, the capacitor C1 is charged through the resistor R1, and the terminal voltage rises as shown in (d). Thereby, the terminal voltage of the capacitor C2 becomes
As shown by the dotted line in (a), the rising speed becomes faster, and the timing at which the control transistor 4 is turned on also becomes faster as shown by the dotted line in (b). As a result, the on / off timing of the switching element 2 gradually increases as shown by the dotted line in (c), and finally the off state is continued. That is, since the load is gradually transferred to the first DC-DC converter and the load sharing does not increase suddenly, it is possible to prevent the output DC voltage from decreasing.

FIG. 3 is an explanatory view of the second embodiment of the present invention, in which the same reference numerals as those in FIG. 1 indicate the same parts, R6 is a resistor, Z
D1 is a Zener diode. In this embodiment, when the monitoring circuit detects that the commercial power source is restored and the phototransistor 6 is turned on, the constant voltage source composed of the resistor R6 and the Zener diode ZD1 causes the capacitor C1 to pass through the resistor R1. The case of charging is shown.

On / off operation of the phototransistor 6 by a power failure detection signal or a power recovery detection signal from a monitoring circuit of a commercial power supply (not shown) and a phototransistor 5 by a control signal corresponding to the difference between the output DC voltage and the set value. The on and off operations of are the same as those of the above-described embodiment, and thus the duplicate description will be omitted. In this embodiment, since the constant voltage source is constituted by the resistor R6 and the Zener diode ZD1 in order to charge the capacitor C1, the monitor circuit detects the restoration of the commercial power source and the phototransistor 6 is detected. After turning on, the timing of turning off the control transistor 4 becomes faster corresponding to the terminal voltage of the capacitor C1 that rises according to the charging time constant. Therefore, the second DC-D
The load on the C converter is gradually reduced to the first DC-
The load on the DC converter is gradually increased, and the switching element 2 is continuously turned off after a certain time regardless of the fluctuation of the battery voltage, and the operation of the second DC-DC converter is stopped. Therefore, there is no abrupt change in load sharing when the commercial power source is restored, and thus fluctuations in the output DC voltage can be prevented.

FIG. 4 is an explanatory view of the third embodiment of the present invention. The same reference numerals as those in FIG. 1 designate the same parts, R7 and R8 are resistors, ZD2 is a zener diode, and 7 is a transistor. In this embodiment, when the monitoring circuit detects that the commercial power source is restored and the phototransistor 6 is turned on,
A case where the capacitor C1 is charged via the resistor R1 by a constant current source composed of the resistors R7 and R8, the Zener diode ZD2 and the transistor 7 is shown.

A phototransistor based on a control signal corresponding to the ON / OFF operation of the phototransistor 6 and a difference between the output DC voltage and the set value in response to a power failure detection signal or a power recovery detection signal from a commercial power supply monitoring circuit (not shown). Since the ON / OFF operation of No. 5 is the same as that of the above-mentioned embodiment, the duplicated description will be omitted. In this embodiment, when the monitor circuit detects the restoration of the commercial power source and turns on the phototransistor 6, the capacitor C1 is connected via the resistor R1.
Is charged by the constant current source, its terminal voltage rises linearly, and the timing at which the control transistor 4 is turned off becomes faster according to the terminal voltage. Therefore, the second
The load of the DC-DC converter is gradually decreased, the load of the first DC-DC converter is gradually increased, and the switching element 2 is continuously turned off after a certain time regardless of the fluctuation of the battery voltage. The operation of the second DC-DC converter is stopped. That is, as in each of the above-described embodiments, there is no abrupt change in load sharing when the commercial power source is restored, so that fluctuations in the output DC voltage can be prevented.

FIG. 5 is an explanatory view of the fourth embodiment of the present invention, in which 11 is a transformer, 12 is a switching element, 13 is a control circuit, 14 is a comparison circuit, 15 is an error amplifier, 16 is a phototransistor, and 17 is a phototransistor. Is a triangular wave oscillator, 18 is a control transistor, 19 is a rectifying / smoothing circuit, 20 is a reference voltage, C1 'is a capacitor, R1', R9 and R10 are resistors, and D4 is a diode.

This embodiment shows the main part of a pulse width control type converter, in which the output DC voltage from the rectifying / smoothing circuit 19 on the secondary side of the transformer 11 and the reference voltage 20 are compared by an error amplifier 15 to obtain a difference. Is added to the comparison circuit 14 and compared with the triangular wave signal TS from the oscillator 17 to control the ON period of the switching element 12. Further, when the commercial power supply is normal, the phototransistor 16 is kept on and is controlled to be turned off when a power failure is detected.

Therefore, when the commercial power supply fails, the phototransistor 16 turns off and the control transistor 1
8 turns on. As a result, the voltage divided by the resistors R1 ′ and R9 is applied to the comparison circuit 14 as the dead time signal DT. The dead time signal DT in this case is usually at a lower level than the difference signal EV.

Next, when the commercial power is restored, the phototransistor 16 is turned on and the control transistor 18 is turned off. As a result, the capacitor C1 'has a resistance R
Since it is discharged via 1'and its terminal voltage gradually decreases, the dead time signal DT, on the contrary, gradually increases and finally becomes + V. By setting this voltage + V to be equal to or higher than the level of the triangular wave signal, the comparison circuit 14 does not output a signal for driving the switching element 12. That is, the ON period of the switching element 12 is gradually shortened, the load of the second DC-DC converter is gradually reduced, and conversely, the load of the first DC-DC converter is gradually increased. , The switching element 12 can be continuously turned off to stop the operation of the second DC-DC converter.

FIG. 6 is a diagram for explaining the operation of the fourth embodiment of the present invention. FIG. 6A shows a triangular wave signal TS, a difference signal EV and a dead time signal D which are input to the comparison circuit 14 (see FIG. 5).
T and (b) and (c) show the drive signal from the comparison circuit 14. When the phototransistor 16 is off, that is, when the commercial power source is out of power, the dead time signal DT is at a low level divided by the resistors R1 ′ and R9,
Further, the capacitor C1 'is charged by the terminal voltage of the resistor R1'. Then, the drive signal corresponding to the difference between the triangular wave signal TS and the error signal EV is output from the comparison circuit 14 as shown in (b), the on period of the switching element 12 is controlled, and the output from the rectifying / smoothing circuit 19 is output. The DC voltage is stabilized.

When the commercial power supply is restored and the phototransistor 16 is turned on at time t0, the control transistor 1 is turned on.
8 is off. Thereby, the capacitor C1 'is discharged through the resistor R1', and its terminal voltage gradually decreases. Therefore, the dead time signal DT gradually increases as shown by the one-dot chain line in (a). When the dead time signal DT exceeds the difference signal EV, the ON period of the switching element 12 gradually shortens as shown in (c). That is, the load on the second DC-DC converter is gradually reduced, and accordingly, the load on the first DC-DC converter is gradually increased, and the load sharing at the time of power recovery of the commercial power source is rapidly increased. Since there is no change, it is possible to prevent fluctuations in the output DC voltage.

The present invention is not limited to the above-mentioned embodiments, but various additions and modifications can be made. For example, the control transistors 4 and 18 can be field effect transistors. In the fourth embodiment, the dead time signal DT is gradually increased by discharging the capacitor C1 ', but the dead time signal DT may be gradually increased by charging. . It is also possible to use various types of configurations as the DC-DC converter.
The C-DC converter and the second DC-DC converter may have different types of configurations.

[0044]

As described above, according to the present invention, the first DC-DC converter that operates using the commercial power supply as the power supply and the second DC-DC that operates using the battery as the power supply.
When the commercial power source has a power failure, the battery is used as a power source to supply power to the load from the second DC-DC converter, and the commercial power source restores the operation of the second DC-DC converter to the capacitor C1 and the resistor. The operation is gradually stopped according to the time constant of charging or discharging with R1, and the second DC
-To gradually shift the load sharing from the DC converter to the first DC-DC converter, which has the advantage of preventing fluctuations in the output DC voltage, and stabilizes the operation of the UPS. You can

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of the fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of an uninterruptible power supply device.

FIG. 8 is an explanatory view of a main part of a conventional RCC converter.

FIG. 9 is an explanatory view of a main part of a conventional pulse width control type converter.

FIG. 10 is an operation explanatory diagram of a conventional example.

FIG. 11 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Transformer 2 Switching Element 3 Control Circuit 4 Control Transistor 5, 6 Phototransistor R1 to R5 Resistor C1 to C4 Capacitor D1 to D3 Diode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kazuki Muneyasu 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Hisao Shimizu 1-17-3, Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Inside Denso Co., Ltd. (72) Inventor Katsuyuki Asahi 1-17-3 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Inside Fuji Denso Co., Ltd.

Claims (5)

[Claims] 1. A first D that operates using a commercial power source as a power source.
In an uninterruptible power supply device that switches a C-DC converter and a second DC-DC converter that operates using a battery as a power source with a detection signal that detects a power failure or power recovery of the commercial power source to supply power to a load, The second DC-DC converter detects the power recovery of the commercial power source, applies a voltage via a resistor, and the second DC-D according to the terminal voltage of the capacitor.
An uninterruptible power supply comprising a control circuit having a configuration for gradually stopping the operation of a C converter. 2. The uninterruptible power supply unit according to claim 1, wherein the uninterruptible power supply unit is configured to charge the capacitor through a resistor from a constant voltage source upon detection of power recovery of the commercial power source. 3. The uninterruptible power supply device according to claim 1, wherein the uninterruptible power supply device is configured to charge the capacitor from a constant current source through the resistor when the power recovery of the commercial power supply is detected. 4. The second DC-DC converter includes a switching element connected to a primary winding of a ringing choke converter type transformer, and a control transistor for controlling an ON / OFF cycle of the switching element. A capacitor for applying a voltage through the resistor upon detection of power recovery of the commercial power source; and a terminal voltage of the capacitor for the control transistor to gradually shorten the ON / OFF cycle of the switching element. The uninterruptible power supply according to claim 1, 2 or 3, further comprising a control circuit including a circuit for switching to an off state. 5. The second DC-DC converter has a switching element connected to the primary winding of a pulse width control type transformer, and detects the voltage of the commercial power source by converting the voltage to the resistance. 2. The device according to claim 1, further comprising: the capacitor applied via the capacitor and a pulse width control circuit applying a terminal voltage of the capacitor as a dead time signal.
Alternatively, the uninterruptible power supply device according to 2 or 3.