JPH1075581A - Uninterrupted power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the voltage fluctuation of an AC power supplied by a commercial power supply and, further, at the time of the service interruption, switch an interrupted power line to an uninterrupted power line without a short break by method in which the output of an inverter is superposed upon the AC power supplied from a bypass line and supplied to a load. SOLUTION: In the positive half cycle of a commercial power supply voltage, if switching devices 12A and 12C are in ON/states, the AC power supplied by a commercial power supply 1 is supplied to a load 7 through a bypass line 20 and, if the switching devices 12A and 12C are in OFF-states, as the energy of a reactor 61 is circulated through a switching device 54A and a diode 56A, an AC voltage applied to the load 7 can be lowered. In the same way, in the negative half cycle of the commercial power supply voltage, if the switching devices 12A and 12C are in ON-states, the AC power supplied by the commercial power supply is supplied to the load 7 through the bypass line 20 and, if the switching devices 12A and 12C are in OFF-states, the energy of the reactor 61 is circulated through a diode 55A and a switching device 53A.

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 an AC power supply from a commercial power supply to a load through a bypass line at all times, and a DC power supply from a storage battery during a power failure. Is converted to AC power by an inverter and supplied to the load, the output voltage accuracy of the continuous commercial power supply type uninterruptible power supply can be improved, and instantaneous interruption switching at the time of power failure can be performed. It's about what you did.

[0002]

2. Description of the Related Art Uninterruptible power supplies of the always commercial power supply type are widely used in various consumer applications because of their high reliability due to the small number of parts.

As shown in FIG. 11, a conventional continuous commercial power supply type uninterruptible power supply has a rectifier circuit 2 for rectifying AC power from a commercial power supply 1 and an electrolytic capacitor 3 for smoothing DC power from the rectifier circuit. A storage battery 4 charged by the DC power, an inverter 5 for converting the DC power to AC power, an uninterruptible line 10 having an AC filter 6 including a reactor 61 and a capacitor 62, and AC power from the commercial power source 1. And a bypass line 20 having a changeover switch 11 composed of thyristors 11A and 11B for supplying the power to the output side of the inverter 5. Normally, AC power is supplied from the bypass line 20 to the load 7 via the changeover switch 11 via the changeover switch 11 In the event of a power failure, the DC power from the storage battery 4 is converted into AC power by the inverter 5 so that the 7 is obtained so as to supply AC power to.

As a specific example of the above-mentioned conventional uninterruptible power supply, as shown in FIG. 12, a rectifier circuit 2A comprises a full-wave rectifier circuit 2A1 and an insulated DC-DC converter 2A2, and the storage battery 4 comprises The inverter 5 is configured to be charged by a charging circuit 41 that converts DC power from the full-wave rectifier circuit 2A into charging power.
1A and a diode 55A are connected in anti-parallel, a parallel circuit in which a switching element 52A and a diode 56A are connected in anti-parallel, a parallel circuit in which a switching element 53A and a diode 57A are connected in anti-parallel, and switching. A device in which a parallel circuit in which an element 54A and a diode 58A are connected in anti-parallel is bridge-connected, or as shown in FIG. 13, a rectifier circuit of a high power factor type having a choke coil 21 on the AC input side. Voltage doubler rectifier 2
B, and the electrolytic capacitor 3 is an electrolytic capacitor 31,
32, two storage batteries 4 are connected in series as storage batteries 41, 42, and an inverter 5 is connected in parallel with a switching element 51B and a diode 55B connected in anti-parallel. It is known that a parallel circuit in which a switching element 52B and a diode 56B are connected in anti-parallel is connected in series.

[0005]

In the above-described conventional uninterruptible power supply, the AC power is supplied from the bypass line 20 to the load 7 when the commercial power 1 is received. Had a problem that

In the conventional uninterruptible power supply described above, the AC power supplied from the bypass line 20 when the commercial power supply 1 is received and the AC power supplied from the uninterruptible line 10 during a power outage are not synchronized. In order to switch the power supply from the bypass line 20 to the power supply from the uninterruptible line 10 without an instantaneous interruption, the inverter 5 must be operated in synchronism with the commercial power supply 1 with no load, and the circuit therefor becomes complicated. Therefore, there is a problem that reliability is reduced due to a small number of parts.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an invention according to claim 1 includes a rectifier circuit for rectifying AC power from a commercial power supply, and an electrolytic capacitor for smoothing DC power from the rectifier circuit. An inverter for converting the DC power to AC power, an uninterruptible line, and a bypass line for supplying AC power from the commercial power supply to an output side of the inverter, and an output of the inverter or an output of the bypass line. In the uninterruptible power supply device configured to supply a load through an AC filter, a control switch in which two parallel circuits in which switching elements and diodes are connected in anti-parallel are connected in series to the bypass line. And a voltage detection circuit for detecting whether the commercial power supply voltage is within an allowable range, and a power failure for detecting a commercial power failure. An output circuit, and a control circuit for controlling the operation of the switching element and the control switch of the inverter. To the load, when the commercial power supply voltage is out of the permissible range, the switching element and the control switch of the inverter are controlled so that the output of the inverter is superimposed on the AC power and supplied to the load. A switching element and a control switch of the inverter are controlled so that DC power from a storage battery is converted into AC power by the inverter and supplied to a load.

According to a second aspect of the present invention, in the uninterruptible power supply according to the first aspect, the rectifier circuit includes a full-wave rectifier circuit and an insulated DC-DC converter, and the storage battery includes a direct current from the rectifier circuit. The inverter is configured to be charged by a charging circuit that converts power to charging power, and the inverter is a bridge-connected parallel circuit in which a switching element and a diode are connected in anti-parallel. .

According to a third aspect of the present invention, in the uninterruptible power supply according to the second aspect, the rectifier circuit includes a high power factor full-wave rectifier circuit having a choke coil inserted on the AC input side or an isolated DC. A high power factor type DC-DC converter in which a choke coil is inserted on the DC input side of the DC converter.

According to a fourth aspect of the present invention, in the uninterruptible power supply according to the first aspect, the rectifier circuit is a voltage doubler rectifier circuit, and two electrolytic capacitors and two storage batteries are connected in series. The inverter is characterized in that two parallel circuits in which switching elements and diodes are connected in anti-parallel are connected in series.

According to a fifth aspect of the present invention, in the uninterruptible power supply according to the fourth aspect, the rectifier circuit is a high power factor type voltage doubler rectifier circuit having a choke coil inserted on the AC input side. It is a feature.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on its embodiments.

FIG. 1 is a circuit diagram of an uninterruptible power supply according to a first embodiment of the present invention. Parts having the same functions as those in FIGS. 11 and 12 are denoted by the same reference numerals.

The feature of the uninterruptible power supply according to the first embodiment of the present invention is that, as shown in FIG. 1, the rectifier circuit 2A comprises a full-wave rectifier circuit 2A1 and an insulated DC-DC converter. The storage battery 4 is configured to be charged by the charging circuit 41 that converts the DC power from the insulated DC-DC converter 2A2 into charging power, and the inverter 5 includes the switching element 51A and the diode 55A connected in anti-parallel. Parallel circuit in which the switching element 52A and the diode 56A are connected in anti-parallel, a parallel circuit in which the switching element 53A and the diode 57A are connected in anti-parallel, and the switching element 54A and the diode 58A are connected in anti-parallel. And a switching element 1 connected to the bypass line 20 by a bridge connection. It is that where A and diode 12B is interposed control switch 12 and connected to the parallel circuit in antiparallel and the switching element 12C and the diode 12D is a parallel circuit connected in inverse parallel are connected in series.

Next, the operation of the uninterruptible power supply according to the first embodiment of the present invention will be described with reference to FIGS. 2, 3, 4 and 5.

FIG. 2 is an operation waveform diagram of each unit when the commercial power supply voltage is within an allowable range during commercial power supply, and the switching elements 51A, 52A, 53A and 54A of the inverter 5 are shown.
And switching elements 12A, 1 of control switch 12
By the control circuit 13 for controlling the operation of the 2C, the switching elements 51A, 52A, 53A, 54A
Are turned off, and the switching elements 12A and 12C of the control switch 12 are turned on so that the AC power from the commercial power supply 1 can be supplied to the load 7 via the control switch 12 and the AC filter 6.

FIG. 3 is an operation waveform diagram of each section when the commercial power supply voltage is below the allowable range during the commercial power supply.
Of the switching element 51A and the switching elements 12A and 12C of the control switch 12 are alternately turned on at a frequency higher than that frequency and with a pulse width corresponding to the peak value.
The switching elements 52A, 5 of the inverter 5 are turned off.
3A is continuously turned off, and the switching element 54A is continuously turned on. In the negative half cycle, the switching element 52A of the inverter 5 and the switching elements 12A and 12C of the control switch 12 are switched at a frequency higher than that frequency. The switching element 53A of the inverter 5 is continuously turned on, and the switching elements 51A and 54A are continuously turned off, by alternately turning on and off with a pulse width corresponding to the peak value.

By controlling as described above, when the commercial power supply voltage is in a positive half cycle, the switching element 12
When A and 12C are on, AC power from commercial power supply 1 is supplied to load 7 via bypass line 20, and when switching elements 12A and 12C are off, inverter 5 is connected via switching elements 51A and 54A. Are superimposed in the positive direction and supplied to the load 7, so that the AC voltage applied to the load 7 can be increased.

Similarly, in the negative half cycle of the commercial power supply voltage, when the switching elements 12A and 12C are on, the AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and the switching element 12A , 12C
Is OFF, the output of the inverter 5 is superimposed in the negative direction via the switching elements 53A and 52A and supplied to the load 7, so that the AC voltage applied to the load 7 can be increased.

FIG. 4 is an operation waveform diagram of each unit when the commercial power supply voltage is higher than the allowable range during the commercial power supply.
The switching element 52A and the switching elements 12A and 12C of the control switch 12 are alternately turned on at a frequency higher than that frequency and with a pulse width corresponding to the peak value.
The switching element 51A, 53A is turned off continuously, and the switching element 54A is turned on continuously. In the negative half cycle, the switching element 51A of the inverter 5 and the switching element 12A,
12C is alternately turned on and off at a frequency higher than that frequency with a pulse width corresponding to the peak value, and the switching 53A is continuously turned on, and the switching elements 52A,
54A is continuously turned off.

By performing the control as described above, the switching element 12 is switched in the positive half cycle of the commercial power supply voltage.
When A and 12C are on, AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and when the switching elements 12A and 12C are off, the reactor is connected via the switching element 54A and the diode 56A. Since the energy 61 is circulated, the AC voltage applied to the load 7 can be reduced.

Similarly, in the negative half cycle of the commercial power supply voltage, when the switching elements 12A and 12C are on, the AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and the switching element 12A , 12C
Is off, the energy of the reactor 61 circulates through the diode 55A and the switching element 53A, so that the AC voltage applied to the load 7 can be reduced.

FIG. 5 is an operation waveform diagram of each part at the time of a power failure. The control circuit 13 turns off the switching elements 12A and 12C of the control switch 12 in the positive half cycle.
The switching element 51A of the inverter 5 is connected to the commercial power supply 1
The switching element 54A is turned on and off alternately at a frequency higher than the frequency of
Are continuously turned on, and the switching elements 52A and 53A are continuously turned off. In the negative half cycle, the switching elements 12A and 12C of the control switch 12 are turned off, and the switching element 52A of the inverter 5 is turned off by the frequency of the commercial power supply 1. At a high frequency, a pulse width corresponding to the peak value is alternately turned on and off, the switching element 53A is continuously turned on, and the switching elements 52A and 54A are continuously turned off.

By controlling as described above, the output from the inverter 5 is supplied to the load 7 via the reactor 61 of the AC filter 6 and the capacitor 62 at the time of a power failure.

The above operation is performed by the voltage detection circuit 13 shown in FIG.
This can be realized by the power failure detection circuit 14 and the control circuit 15.

That is, the voltage detection circuit 13 determines that the commercial power supply voltage is within the allowable range, for example, 100 V, as the voltage detection signal.
In the case of a system, an L level signal is transmitted when the voltage is 95 V to 105 V, and an H level signal is transmitted when the voltage is 95 V or less or 105 V or more.

Further, the power failure detection circuit 14 sends an L level signal as a power receiving power failure signal when the commercial power source 1 fails,
An H level signal is transmitted when the commercial power supply 1 receives power.

The control circuit 15 also includes an error amplifier 151 for amplifying an error between the AC voltage applied to the load 7 and the reference voltage and transmitting an error signal. The error amplifier 151 compares the error signal with a positive triangular wave to generate a positive signal. A positive comparator 152A for transmitting a comparison signal,
A negative comparator 152B for comparing the error signal with a negative triangular wave and transmitting a negative comparison signal; a zero potential comparator 153 for comparing the reference voltage with zero potential and transmitting an output; The output of the side comparator 152A is input to the AND circuit 154A together with the output of the voltage detection circuit 13, and the output of the AND circuit 154A is converted into a drive signal for the switching element 51A by the drive circuit 155A. The output of 153 is converted into a drive signal for the switching element 52A by the drive circuit 155B, and the output of the negative comparator 152B is input to the AND circuit 154B together with the output of the voltage detection circuit 13.
4B is converted into a drive signal for the switching element 53A by a drive circuit 155C,
The output of No. 3 is converted into a drive signal of the switching element 54A by the inversion circuit 156 and the drive circuit 155D. Further, the output of the positive side comparator 152A and the negative side comparator 152
The output of B is input to the inverted OR circuit 157, and the output of the inverted OR circuit 157 is input to the AND circuit 158 together with the power failure detection signal from the power failure detection circuit 14, and the output of the AND circuit 158 is output. Are the switching elements 12A, 1 of the control switch 12 by the drive circuit 155E.
It is converted into a 2C drive signal.

In the first embodiment described above, the rectifier circuit 2A comprises the full-wave rectifier circuit 2A1 and the insulated DC-DC converter 2A2.
A high power factor type full-wave rectifier circuit by inserting a choke coil on the AC input side of
2 may be a high power factor type DC-DC converter in which a choke coil is inserted on the DC input side.
As the DC converter 2A2, a push-pull type, a forward type, or the like can be used in addition to the full bridge type as shown. Further, instead of the rectifier circuit 2A including the full-wave rectifier circuit 2A1 and the insulated DC-DC converter 2A2, a full-wave rectifier circuit insulated by a commercial transformer may be used.

FIG. 6 is a circuit diagram of an uninterruptible power supply according to a second embodiment of the present invention. Parts having the same functions as those in FIGS. 1, 11 and 13 are denoted by the same reference numerals.

The feature of the uninterruptible power supply according to the second embodiment of the present invention is that, as shown in FIG. 6, the rectifier circuit is a high power factor double type having a choke coil 21 on the AC input side. It comprises a voltage rectifier circuit 2B, two electrolytic capacitors 3 are connected in series like electrolytic capacitors 31 and 32, a storage battery 4 is connected in series like storage batteries 41 and 42, and an inverter 5 is a switching element. A parallel circuit in which a switching element 52B and a diode 56B are connected in anti-parallel and a parallel circuit in which a switching element 52B and a diode 56B are connected in anti-parallel are connected in series. 12B and a parallel circuit in which a switching element 12C and a diode 12D are connected in anti-parallel. Control switch connected in series 1
2 is inserted.

Next, the operation of the uninterruptible power supply according to the second embodiment of the present invention will be described with reference to FIGS. 7, 8, 9 and 10.

FIG. 7 is an operation waveform diagram of each part when the commercial power supply voltage is within the allowable range during the commercial power supply, and shows the operation of the switching elements 51B and 52B of the inverter 5 and the switching elements 12A and 12C of the control switch 12. By the control circuit 13 for controlling, the switching elements 51B and 52B of the inverter 5 are all turned off and the switching elements 12A and 12C of the control switch 12 are turned on, and the AC power from the commercial power source 1 is supplied to the control switch 12 and the AC filter 6 Through the load 7.

FIG. 8 is an operation waveform diagram of each part when the commercial power supply voltage is below the allowable range during commercial power supply.
Of the switching element 51B and the switching elements 12A and 12C of the control switch 12 are alternately turned on at a frequency higher than that frequency and with a pulse width corresponding to the peak value.
Off, and the switching element 52B of the inverter 5 is continuously turned off.
The switching element 52B of the control switch 12 and the switching elements 12A and 12C of the control switch 12 are alternately turned on at a frequency higher than that frequency and with a pulse width corresponding to the peak value.
The switching element 51B of the inverter 5 is continuously turned off.

By performing the control as described above, the switching element 12 is switched in the positive half cycle of the commercial power supply voltage.
When A and 12C are on, AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and when the switching elements 12A and 12C are off, the switching power is supplied via the switching element 51B and the electrolytic capacitor 32. Since the output of the inverter 5 is superimposed in the positive direction and supplied to the load 7, the AC voltage supplied to the load 7 can be increased.

Similarly, in the negative half cycle of the commercial power supply voltage, when the switching elements 12A and 12C are on, the AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and the switching element 12A , 12C
Is off, the output of the inverter 5 is superposed in the negative direction via the electrolytic capacitor 31 and the switching element 52B and supplied to the load 7, so that the AC voltage supplied to the load 7 can be increased.

FIG. 9 is an operation waveform diagram of each part when the commercial power supply voltage is higher than the allowable range during the commercial power supply.
The switching element 52B of the control switch 12 and the switching elements 12A and 12C of the control switch 12 are alternately turned on at a frequency higher than that frequency and with a pulse width corresponding to the peak value.
Off, and the switching element 51B of the inverter 5 is continuously turned off.
Of the switching element 51B and the switching elements 12A and 12C of the control switch 12 are alternately turned on at a frequency higher than that frequency and with a pulse width corresponding to the peak value.
The switching element 51B of the inverter 5 is continuously turned off.

By controlling as described above, when the commercial power supply voltage is in a positive half cycle, the switching element 12
When A and 12C are on, AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and when the switching elements 12A and 12C are off, the reactor is connected via the electrolytic capacitor 32 and the diode 56B. 61
Circulates, the AC voltage applied to the load 7 can be reduced, and the current waveform flowing through the choke coil 21 can be approximated to a sine wave.

Similarly, in the negative half cycle of the commercial power supply voltage, when the switching elements 12A and 12C are on, the AC power from the commercial power supply 1 is supplied to the load 7 via the bypass line 20, and the switching element 12A , 12C
Is off, the diode 55B and the electrolytic capacitor 3
Since the energy of the reactor 61 circulates through the AC power supply 1, the AC voltage applied to the load 7 can be reduced,
Moreover, the waveform of the current flowing through the choke coil 21 can be approximated to a sine wave.

FIG. 10 is an operation waveform diagram of each part at the time of a power failure.
In the positive half cycle of the control circuit 13, the switching elements 12A and 12C of the control switch 12 are turned off, and the switching element 51B of the inverter 5 is turned on at a frequency higher than the frequency of the commercial power supply 1 at a pulse width corresponding to the peak value. To turn on and off alternately by switching element 5
In the negative half cycle, the switching elements 12A and 12C of the control switch 12 are turned off, and the switching element 52B of the inverter 5 is turned off at a frequency higher than the frequency of the commercial power supply 1 and corresponds to the peak value. The switching element 5 is turned on and off alternately by a pulse width.
1B is continuously turned off.

By controlling as described above, at the time of a power failure, the output from the inverter 5 is supplied to the load 7 via the reactor 61 of the AC filter 6 and the capacitor 62.

The above operation is performed by the voltage detection circuit 13 shown in FIG.
This can be realized by the power failure detection circuit 14 and the control circuit 15.

That is, the voltage detection circuit 13 determines that the commercial power supply voltage is within the allowable range, for example, 100 V as the voltage detection signal.
In the case of a system, an L level signal is transmitted when the voltage is 95 V to 105 V, and an H level signal is transmitted when the voltage is 95 V or less or 105 V or more.

The power failure detection circuit 14 transmits an L level signal as a power failure signal when the commercial power supply 1 fails,
An H level signal is transmitted when the commercial power supply 1 receives power.

The control circuit 15 also includes an error amplifier 151 for amplifying an error between the AC voltage applied to the load 7 and the reference voltage and transmitting an error signal. The error amplifier 151 compares the error signal with a positive triangular wave to generate a positive signal. A positive comparator 152A for transmitting a comparison signal,
A negative comparator 152B for comparing the error signal with the negative triangular wave and transmitting a negative comparison signal;
The output of 52A is input to the AND circuit 154A together with the output of the voltage detection circuit 13, and this AND circuit 154A
The output of A is a driving signal of the switching element 51B by the driving circuit 155A, and the output of the negative comparator 152B is the AND circuit 1 together with the output of the voltage detecting circuit 13.
The driving circuit 155B converts the output of the AND circuit 154B into a driving signal for the switching element 52B. Further, the output of the positive side comparator 152A and the output of the negative side comparator 152B
57, and the output of the inverted OR circuit 157 is input to the AND circuit 158 together with the power failure detection signal from the power failure detection circuit 14. The signals are converted into drive signals for the elements 12A and 12C.

In the above-described second embodiment, the rectifier circuit is composed of the high power factor type voltage doubler rectifier circuit 2B in which the choke coil 21 is inserted on the AC input side. It may be.

In each of the above-described embodiments, the control switch 12 and the switching element of the inverter 5 are illustrated as bipolar transistors. However, it is needless to say that other than bipolar transistors such as IGBT and FET may be used. No.

[0048]

As described above, according to the present invention, the voltage fluctuation of the AC power supplied from the commercial power supply to the load can be reduced, and the power supply can be switched to the power supply from the uninterruptible line without interruption at the time of power failure. Therefore, it is possible to contribute to the improvement of the performance of the continuous commercial power supply type uninterruptible power supply.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an uninterruptible power supply according to a first embodiment of the present invention.

FIG. 2 is an operation waveform diagram of each unit of the uninterruptible power supply according to the first embodiment when a commercial power supply voltage is within an allowable range.

FIG. 3 is an operation waveform diagram of each unit of the uninterruptible power supply when the commercial power supply voltage is below an allowable range.

FIG. 4 is an operation waveform diagram of each unit of the uninterruptible power supply when the commercial power supply voltage is higher than an allowable range.

FIG. 5 is an operation waveform diagram of each unit of the uninterruptible power supply at the time of a power failure.

FIG. 6 is a circuit diagram of an uninterruptible power supply according to a second embodiment of the present invention.

FIG. 7 is an operation waveform diagram of each unit of the uninterruptible power supply according to the first embodiment when a commercial power supply voltage is within an allowable range.

FIG. 8 is an operation waveform diagram of each unit of the uninterruptible power supply when the commercial power supply voltage is below an allowable range.

FIG. 9 is an operation waveform diagram of each unit of the uninterruptible power supply when the commercial power supply voltage is higher than an allowable range.

FIG. 10 is an operation waveform diagram of each unit of the uninterruptible power supply at the time of power failure.

FIG. 11 is a circuit diagram of a conventional uninterruptible power supply.

FIG. 12 is a circuit diagram of a conventional uninterruptible power supply.

FIG. 13 is a circuit diagram of a conventional uninterruptible power supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Rectifier circuit 3 Electrolytic capacitor 4 Storage battery 5 Inverter 6 AC filter 7 Load 10 Uninterruptible line 12 Control switch 13 Power failure detection circuit 14 Voltage detection circuit 15 Control circuit 20 Bypass line

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H02M 7/06 8726-5H H02M 7/06 G // H02M 3/28 3/28 H

Claims (5)

[Claims] 1. A rectifier circuit for rectifying AC power from a commercial power supply, an electrolytic capacitor for smoothing DC power from the rectifier circuit, a storage battery charged by the DC power, and converting the DC power to AC power. And a bypass line for supplying AC power from the commercial power supply to an output side of the inverter, and an output of the inverter or an output of the bypass line to a load via an AC filter. In the uninterruptible power supply device to be supplied, a control switch in which two parallel circuits each having a switching element and a diode connected in antiparallel are connected in series to the bypass line, and the commercial power supply voltage is within an allowable range. A voltage detection circuit for detecting whether the voltage is within the range, a power failure detection circuit for detecting a power failure of the commercial power supply, A switching element of the inverter and a control circuit for controlling the operation of the control switch, and when commercial power is supplied, if the commercial power voltage is within an allowable range, AC power from the commercial power is supplied to the load via the bypass line. When the commercial power supply voltage is outside the allowable range, the switching element and the control switch of the inverter are controlled so that the output of the inverter is superimposed on the AC power and supplied to the load. An uninterruptible power supply, wherein a switching element and a control switch of the inverter are controlled so that the power is converted into AC power by the inverter and supplied to a load. 2. The uninterruptible power supply according to claim 1, wherein the rectifier circuit comprises a full-wave rectifier circuit and an insulated DC-DC converter, and the storage battery converts DC power from the rectifier circuit into charging power. An uninterruptible power supply device configured to be charged by a circuit, wherein the inverter is a bridge-connected parallel circuit in which a switching element and a diode are connected in anti-parallel. 3. The uninterruptible power supply according to claim 2, wherein the rectifier circuit is a high power factor full-wave rectifier circuit having a choke coil inserted on the AC input side or a DC input side of an insulated DC-DC converter. An uninterruptible power supply, characterized in that it is a high power factor DC-DC converter with a choke coil interposed. 4. The uninterruptible power supply according to claim 1, wherein the rectifier circuit is a voltage doubler rectifier circuit, two electrolytic capacitors and two storage batteries are connected in series, and the inverter has a switching element and a diode. An uninterruptible power supply characterized in that two parallel circuits connected in anti-parallel are connected in series. 5. The uninterruptible power supply according to claim 4, wherein the rectifier circuit is a high power factor doubler rectifier circuit having a choke coil inserted on the AC input side.