JP2906107B2 - Boost type uninterruptible power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step-up type uninterruptible power supply.

[0002]

2. Description of the Related Art Conventionally, the above-mentioned step-up type uninterruptible power supply is, for example, as shown in FIG. This uninterruptible power supply has input terminals 10, 1 connected to a commercial AC power supply.
When the input terminal 10 has a positive half-wave whose potential is higher than that of the input terminal 12, the capacitor 18 is charged via the high-frequency noise removing coil 14 and the current limiting resistor 16. For example, when the voltage of the commercial AC power supply has an effective value of 100 V, 14
Charge to 0V. When the charging is completed, the triac 20 connected in parallel with the current limiting resistor 16 receives a gate signal from a control circuit (not shown) and becomes conductive, and the current limiting resistor 16
Short circuit.

During the period of the positive half-wave, a gate signal having a frequency of, for example, 15 to 20 kHz is supplied to a switching element 22 such as an IGBT from a control circuit (not shown), and the switching element 22 responds to the gate signal. On and off. When the switching element 22 is in an ON state, it flows to the capacitor 28 via the AC power source, one input terminal 10, the high-frequency noise removing coil 14, the triac 20, the reactor 26, and the switching element 22, and reversely charges or discharges the capacitor 28. I do.

When the switching element 22 is off,
A voltage is generated in the reactor 26 in a direction indicated by an arrow, and a current is supplied from the reactor 26 to a switching element 29 such as an IGBT connected in series with the switching element 22.
Then, the current flows through the capacitor 32 connected in series with the capacitor 28 via the diode 30 connected in anti-parallel, and further flows to the high-frequency noise removing coil 14 and the other input terminal 12. At this time, the capacitor 32 is charged to the polarity shown in FIG. 2, and its maximum voltage is boosted to the sum of the AC power supply voltage and the back electromotive force of the reactor 26, usually 200
V is boosted.

On the other hand, in the case of a negative half-wave in which the potential of the terminal 10 is lower than the potential of the terminal 12, A current flows, and the capacitor 18 is charged. Also, input terminal 1
2, a current flows through the diode 46, the reactor 26, the triac 20, the high-frequency noise removing coil 14, and the input terminal 10 which are connected in anti-parallel to the high-frequency noise removing coil 14, the capacitor 28, and the switching element 22, and the capacitor 28 is charged. .

During the period of the negative half-wave, the switching element 29 is repeatedly turned on and off in the same manner as the switching element 22 by a gate signal having a frequency of, for example, 15 to 20 kHz supplied from a control circuit (not shown). When the switching element 29 is on, a current flows from the AC power supply, the other input terminal 12, and the high-frequency noise removing coil 14 to the capacitor 32, the switching element 29, and the reactor 26, and the capacitor 32 is reversely charged or discharged.

When the switching element 29 is off,
A voltage in the direction opposite to the arrow is generated in the reactor 26, and current flows from the reactor 26 to the reactor 26 via the triac 20, the high-frequency noise removing coil 14, the AC power supply, the high-frequency noise removing coil 14, the capacitor 28, and the antiparallel diode 46. The capacitor 28 is charged to the polarity shown in FIG. 2, and its maximum voltage is boosted to the sum of the AC power supply voltage and the back electromotive force of the reactor 26, typically 200V.

The switching elements 34, 3 such as IGBTs connected in series between the capacitors 32, 28
6, the switching element 34 is made conductive for a certain period by a gate signal from a control circuit (not shown). As a result, the electric charge of the capacitor 32 flows through the switching element 34, the output reactor 38, the high-frequency noise removing coil 40, the output terminal 42, the load (not shown), the output terminal 44, the high-frequency noise removing coil 40, and flows into the capacitor 32. Is supplied with an AC output.

When the switching element 36 is turned on for a predetermined time, the high-frequency noise removing coil 40, the output terminal 44, the load (not shown),
2, high frequency noise removing coil 40, output reactor 3
8. A current flows to the capacitor 28 via the switching element 36, and an AC output is supplied to the load.

Note that 48 and 50 are switching elements 3
4, 36 are diodes connected in anti-parallel.

In the power supply device shown in FIG. 2, the switching element 52 and the storage battery 54 are provided between the capacitors 28 and 32.
Are connected, and the connection point of these two is
It is connected to a connection point between the capacitor 32 and the switching element 34 via a diode 56. The switching element 52 is turned on by a gate signal from a control circuit (not shown) while the commercial AC power is being supplied, and charges the storage battery 54.

When the commercial AC power supply is cut off, the voltage of the storage battery 54 is applied across the switching elements 34 and 36 via the diode 56, and the switching elements 34 and 36 are switched in the same manner as described above. The element 34 is turned on for a predetermined period of time corresponding to the positive half-wave,
The switching element 36 is repeatedly turned on for a predetermined period of time corresponding to the negative half-wave, and supplies an AC output to the load in the same manner as before the power failure even if the power failure occurs.

Reference numeral 58 denotes a high-frequency noise removing coil 1.
The switching elements 22, 29, 34, 36, the capacitor 2
This switch is turned on when performing maintenance and inspection of the step-up type inverter circuit composed of 8, 32, and the like, and supplies commercial AC power to the load via the high-frequency noise removing coils 14 and 40.

[0014]

However, in the uninterruptible power supply as described above, since the voltage of the capacitors 28 and 32 is 400 V, the storage battery 54 must be capable of generating a voltage of 400 V or more. There is a problem that the apparatus has to be used and the apparatus becomes large.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a first and second switching elements connected in series, and the first and second switching elements having the same direction. First and second diodes connected in anti-parallel with each other, first and second capacitors connected in series between the first and second switching elements, and between the first and second capacitors. Connected inverter and the first
And a series circuit of the first switching means and the reactor, which is connected between the connection point of the second switching element and one terminal of the AC power supply and is opened at the time of power failure, the second switching means and the storage battery which are short-circuited at the time of power failure. A series circuit, a connection point between the reactor and the first switching means, a third switching means connected between a connection point between the second switching element and the second capacitor and turned on at least at the time of power failure , First and second
A first input terminal connected to a connection point of the capacitor , the first switching element is periodically turned on / off when the AC power supply has one polarity, and the second switching element is A step-up type uninterruptible power supply which is periodically turned on / off when the AC power has the other polarity and when the AC power is out of power.

[0016]

According to the present invention, when the AC power supply has one polarity,
The first switching element repeatedly turns on and off, and in the on state, current flows from the AC power supply to the reactor. When the first switching element is in the off state, a back electromotive force is generated in the reactor, and a current flows from the reactor to the second capacitor and the AC power supply, and the voltage of the second capacitor is equal to the AC power supply voltage and the counter electromotive force of the reactor. It is a voltage that is the sum of the power and the power. That is, the voltage of the second capacitor is higher than the voltage of the AC power supply.

When the AC power supply has the other polarity, the second switching element repeatedly turns on and off. When the AC power supply has a positive polarity, a current flows in the opposite direction from the AC power supply to the reactor. Electric current flows.
When the second switching element is in the off state, a back electromotive force is generated in the first reactor, and the back electromotive force and the AC power supply voltage are applied to the first capacitor. Higher than the voltage of

When the AC power supply fails, the first switching means is opened, the second switching means is short-circuited, and the second switching element is repeatedly turned on and off. When the second switching means is short-circuited, current flows from the storage battery to the reactor. When the second switching element is turned off, back electromotive force is generated in the reactor. This voltage and the voltage of the storage battery are added and applied between the first and second capacitors. That is, the voltage of the storage battery is increased, and the first and second
Is applied between the capacitors.

[0019]

FIG. 1 shows an embodiment of an uninterruptible power supply according to the present invention. Note that the same reference numerals are given to the same parts as those of the related art shown in FIG. 2, and the description thereof will be omitted.

In this embodiment, the series circuit of the reactor 26 and the first opening / closing means 76 and the series circuit of the storage battery 60 and the second opening / closing means 78 are composed of an AC power supply and the first and second switching elements 22 and 29. Connected between connection points. A diode 72 is connected between a connection point between the reactor 26 and the first opening / closing means and a connection point between the second switching element 29 and the second capacitor 32.

In this embodiment, the first opening / closing means 76 is turned on while the commercial AC power supply is applying a voltage to the input terminals 10 and 12, and the same as described with reference to FIG. Thus, an AC output is supplied to the load.

If a power failure occurs in this state, a detector (not shown) detects this power failure state, the first opening / closing means 76 is opened via a control circuit (not shown), and the second opening / closing hand is short-circuited.

A control circuit (not shown) supplies a gate signal having a frequency of 15 kHz to 20 kHz to the switching element 29 at the same time to turn on / off the switching element 29.
Turn off. When the commercial AC power is supplied, the gate signal supplied to the switching element 29 is
It occurs only during the period corresponding to the negative polarity, but in the power failure state, it occurs continuously until the power failure recovers.

When the switching element 29 is short-circuited,
A current is supplied from the storage battery 60 to the reactor 26 via the storage battery 60, the reactor 26, the diode 72, the switching element 29, and the second opening / closing means 78. And
When the switching element 29 is off, the reactor 2
6, a back electromotive force is generated in the direction indicated by the arrow in FIG. 1, and current flows through the diode 72, the capacitors 32 and 28, the diode 46, the switching means 78, and the storage battery 60, and
A voltage obtained by adding the voltage of the reactor 26 and the voltage of the storage battery 60, that is, a voltage obtained by boosting the voltage of the storage battery 60 is applied between 2 and 28. The voltage between the capacitors 32 and 28 is
On / off control, that is, inverter control, is performed by the switching elements 34 and 36, and supplied to the load.

In the above embodiment, the switching element 2
IGBT was used for 2, 29, 34, and 36, but other FEBT
T, a bipolar transistor or the like can also be used. Further, the first opening / closing means and the second opening / closing means may be not only relays but also electronic switches. Further, instead of the diode 72, a relay or an electronic switch that short-circuits during a power failure may be used. The storage battery is charged from a charger (not shown) when the AC power supply is normal.

[0026]

As described above, according to the present invention, the series circuit of the switching means and the reactor, which is opened at the time of a power failure, between the first and second switching connection points and one terminal of the AC power supply. A series circuit of an opening / closing means and a storage battery, which is short-circuited at the time of a power failure, is provided.
The third switching means that is turned on at the time of a power failure is provided at the connection point between the switching element and the second capacitor, so that the voltage of the storage battery is increased by turning on and off the second switching element. It can be applied between the second capacitors. Therefore, a storage battery that generates a voltage lower than the voltage applied to the first or second capacitor when the AC power is supplied can be used as the storage battery.
This uninterruptible power supply can be downsized.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram of a conventional uninterruptible power supply.

[Explanation of symbols]

 Reference Signs List 18 (input) capacitor 22 (first) switching element 26 reactor 28 (first) capacitor 29 (second) switching element 30 diode 32 (second) capacitor 34 switching element (inverter) 36 switching element (inverter) ) 46 diode 60 battery 72 (third) opening / closing means 76 (first) opening / closing means 78 (second) opening / closing means

──────────────────────────────────────────────────の Continuation of the front page Examiner Yoshinori Shingu (56) References JP-A-2-168867 (JP, A) JP-A-4-289782 (JP, A) JP-A-61-102172 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) H02M 7/5387 H02J 7/00 302 H02M 3/155 H02M 7/48

Claims (1)

(57) [Claims] A first and a second switching element connected in series; a first and a second diode connected in antiparallel to the first and the second switching element in the same direction; First and second capacitors connected in series between the first and second switching elements, an inverter connected between the first and second capacitors, and a connection point of the first and second switching elements And a series circuit of a first switching means and a reactor, which is connected between one terminal of the AC power supply and is opened at the time of a power failure, a series circuit of the second switching means and a storage battery which is short-circuited at the time of a power failure, a connection point between the first switching means, a third switching means to be turned on when connected to at least a power failure during the connection point of the second switching element and the second capacitor, the first and second con
A second input terminal connected to a connection point of the capacitor , the first switching element is periodically turned on / off when the AC power supply has one polarity, and the second switching element is A step-up type uninterruptible power supply which is periodically turned on / off when the AC power has the other polarity and when the AC power is out of power.