JPH0759360A - Uninterruptive power unit - Google Patents

Abstract

PURPOSE:To suppress the deterioration of the electromagnetic environment of load by connecting the junction between a first capacitor and a second capacitor and the tap of a tapped inductance with each other. CONSTITUTION:A center tapped inductance LT is connected to the section between the power terminals T1 and T2 of a circuit, and a pair of AC input terminals of the converter comprising four switches Q1-Q4 being connected in bridge are connected to the power terminals T1 and T2 through reactors L1 and L2. Moreover, the series connection circuit of smoothing capacitors CA and CB is connected to the section between a pair of power lines 7 and 8 connected to the DC output terminal of a converter 1, and the junction N is connected to the tap of an inductance LT. As a result, the voltage between the neutral point on the input power side and the DC power line does not ripple by the switching operation of the switches Q1-Q4, and further excessive high frequency power flowing in the connection PN is suppressed effectively by a reactor, and the adverse effect on the electromagnetic environment of load is effectively suppressed.

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, and more particularly to an uninterruptible power supply device in which interference noise to other electronic devices is effectively suppressed and the electromagnetic environment is good. .

[0002]

2. Description of the Related Art The basic function of an uninterruptible power supply is to supply clean power to a load computer or the like even when a commercial power supply on the input side fails. The commercial power source is always used as an energy source, and the stored energy stored in a storage battery or the like is used as an energy source during a power failure to supply power to the load.

FIG. 2 is an electric circuit diagram showing a conventional non-stop power supply device. Referring to FIG. 2, AC power supply E is connected to power supply terminals T1 and T2 of the uninterruptible power supply. A pair of AC input terminals of the converter 1 including four switches Q1, Q2, Q3, Q4 connected in a bridge are connected to power supply terminals T1, T2 via a reactor L. Each switch Q
1, Q2, Q3 and Q4 are composed of power MOSFETs having a built-in freewheeling diode. The converter 1 converts AC power into DC power. Converter 1
Is for controlling the DC voltage of the output of the converter by on / off controlling each of the switches Q1 to Q4. Between the pair of power lines 7 and 8 connected to the DC output terminal of the converter 1, the smoothing capacitor C, the inverter 2 and the power source for power failure backup, that is, the storage battery B as an emergency energy supply source are connected. In normal times, the storage battery B is charged by the AC power source E. When the AC power source E fails, the energy stored in the storage battery B is supplied to the inverter 2. The inverter 2 is composed of four switches S1, S2, S3 and S4 which are bridge-connected. Each of the switches S1, S2, S3, S4 is composed of a power MOSFET having a freewheeling diode built therein. The inverter 2 outputs the flowing power having a constant frequency and a constant voltage by PWM-controlling the switches S1 to S4. The AC output terminal of the inverter 2 has a filter circuit including a reactor LF and a capacitor CF and a transformer T.
Is connected to load terminals T3 and T4. The load 3 is connected between the load terminals T3 and T4. Furthermore,
In FIG. 2, the direct feed circuit 4 is connected between the power supply terminals T1 and T2 and the load terminals T3 and T4. The direct transfer circuit 4 switches the power supply to the load 3 from the inverter 2 side to the commercial power supply E side when the rush current of the load 3 or an overload occurs.

Here, the conventional problems will be described.
The switches Q1 and Q3 of the converter 1 are turned on, and the switch Q
When Q2 and Q4 are turned off, the potential of the power line 7 becomes equal to that of the power supply terminal T2, and when the switches Q1 and Q3 are turned off and the switches Q2 and Q4 are turned on, the potential of the power line 8 and the power supply terminal T2 are changed. Will be equal. Therefore,
Conventionally, the voltage between the neutral point potential of the power source E and the neutral point potentials of the DC power lines 7 and 8 has fluctuated greatly due to the switching operation of the switches Q1 to Q4 of the converter 1. Due to this fluctuation, disturbance noise is induced in other electronic devices via the stray capacitances CSP, CSN of the DC lines 7 and 8, and the electromagnetic environment is polluted. Further, this fluctuation is caused by the inverter 2, the output-side filter circuit L including the reactor LF and the capacitor CF, and the drift capacitance between the primary and secondary windings of the transformer T, and the electromagnetic environment of the load 3. Was getting worse.

Further, another problem will be described. Usually, in an uninterruptible power supply device equipped with the direct feed circuit 4, an insulating transformer is used in its output part. This insulating transformer suppresses a large circulating current that circulates through the converter 1, the inverter 2, and the direct feed circuit 4.
Further, it is possible to effectively prevent the load from being adversely affected by the electrical interference noise generated by the switching of the power switching element inside the uninterruptible power supply. However, this isolation transformer T is expensive, and its mass is very heavy, and moreover, it causes a loss.

[0006]

Therefore, the main object of the present invention is to suppress the deterioration of the electromagnetic environment of the load. Another object of the present invention is to suppress application of electromagnetic interference noise to other electronic devices and to reduce electrical interference noise. Further, another object of the present invention relates to an uninterruptible power supply device and a power supply method thereof, which can reduce electric interference noise to a load without relying on an insulating transformer. Still another object of the present invention is to provide an uninterruptible power supply device and a power feeding method thereof that can reduce loss. Another object of the present invention is to provide an uninterruptible power supply device suitable for downsizing and weight saving, and a power feeding method thereof.

[0007]

According to a first aspect of the present invention, there is provided an uninterruptible power supply device for supplying electric power to a load, the power supply terminal and an inductance with a tap connected in parallel between the power supply terminals. A first capacitor and a second capacitor, each of which includes a converter having an input terminal connected to a power supply terminal, first and second capacitors connected in series to an output side of the converter, and an inverter connected to an output side of the converter. It is configured to connect the connection point with the capacitor of and the tap of the tapped inductance. The invention according to claim 2 is an uninterruptible power supply device for supplying electric power to a load, wherein a power supply terminal, a neutral point terminal, a converter whose input terminal is connected to the power supply terminal, and an output side of the converter are connected in series. A first and second capacitors connected to each other and an inverter connected to the output side of the converter; and a connection point between the first capacitor and the second capacitor and a neutral point terminal To be done. The invention according to claim 3 prevents excessive current from flowing between the connection point and the tap by inserting a pair of reactors in the power supply line between the power supply terminal and the converter of the invention according to claim 1. Configured to suppress. The invention according to claim 4 is an uninterruptible power supply device for supplying electric power to a load, wherein the power supply terminal, the neutral point terminal, the converter connected to the power supply terminal, and the output side of the converter are connected in series. The first and second capacitors and an inverter connected to the output side of the converter are provided, the connection point between the first capacitor and the second capacitor and the neutral point terminal are connected, and the power supply terminal and the converter are connected. And are connected via a pair of reactors. According to a fifth aspect of the present invention, in addition to the first aspect of the present invention, a series circuit including third and fourth capacitors connected to the output side of the inverter, and a series circuit including the inverter, the third and the capacitors. A pair of reactors inserted in a pair of power lines between the circuit and a connection point between the first capacitor and the second capacitor and a connection point between the third capacitor and the fourth capacitor Is configured as follows. The invention according to claim 6 is the invention according to claim 2.
In the invention according to the first aspect, further, a pair of reactors is provided between the series circuit including the third and fourth capacitors connected to the output side of the inverter and the series circuit including the inverter and the third and fourth capacitors. And a connection point between the first capacitor and the second capacitor and a connection point between the third capacitor and the fourth capacitor. The invention according to claim 7 is the same as the invention according to claim 4, further comprising a series circuit including third and fourth capacitors connected to the output side of the inverter, the inverter, and the third and fourth capacitors. And a series circuit including a pair of reactors, and is configured to connect a connection point between the first capacitor and the second capacitor and a connection point between the third capacitor and the fourth capacitor. .

[0008]

[Operation] By connecting the tap of the tap inductance connected in parallel to the power supply terminal or the neutral point terminal to the connection point of the first and second capacitors connected in series on the output side of the converter, The adverse effect of the load on the electromagnetic environment due to the switching of the converter is effectively suppressed. Further, by connecting the connection point of the third and fourth capacitors connected in series to the output side of the inverter connected to the output side of the converter and the connection point of the first and second capacitors, the load The potential fluctuation of the neutral point was suppressed and the electromagnetic environment of the load was improved. Furthermore, the tap of the tap inductance connected in parallel to the power supply terminal or the neutral point terminal, the connection point of the first and second capacitors connected in series to the output side of the converter, and the output side of the converter. By connecting the output side of the connected inverter to the connection point of the third and fourth capacitors connected in series, the potential fluctuation of the neutral point of the load was suppressed. As a result, it is possible to use the direct transfer circuit without using the insulating transformer on the output side.

[0009]

1 is an electric circuit diagram showing a first embodiment of the present invention. Referring to FIG. 1, AC power supply E is connected to power supply terminals T1 and T2. In addition, power supply terminals T1, T
An inductor LT with a center tap is connected between the two. The windings of the inductance LT are tightly coupled to each other, and the inductance LT has a high impedance with respect to the frequency of the AC power source E, and the exciting current flowing through the inductance LT is small. A pair of AC input terminals of the converter 1, which is composed of four switches Q1, Q2, Q3, Q4 connected in a bridge, are reactors L1, L
2 is connected to power supply terminals T1 and T2. Each of the switches Q1, Q2, Q3, Q4 is composed of a power MOSFET having a freewheeling diode built therein. Converter 1
Is for converting AC power to DC power. Then, the converter 1 controls the DC voltage of the output of the converter by controlling ON / OFF of each of the switches Q1 to Q4. A series connection circuit of smoothing capacitors CA and CB is connected between the pair of power lines 7 and 8 connected to the DC output terminal of the converter 1. The connection point N between these capacitors CA and CB is connected to the tap of the inductance LT. Inverter 2 and an emergency energy supply source, that is, a storage battery B as a power source for power failure backup are further connected between the power lines 7 and 8. In normal times, the storage battery B is charged by the AC power source E. When the AC power source E fails, the energy stored in the storage battery B is supplied to the inverter 2. The inverter 2 is formed by connecting switches S1, S2, S3 and S4 in a bridge. Each of the switches S1, S2, S3, S4 is composed of a power MOSFET having a freewheeling diode built therein.
The inverter 2 has an operating frequency higher than an audible frequency of about 20 kHz for noise reduction, performs sine wave modulation, and outputs an AC voltage having a constant frequency and a constant voltage. The AC power output from the output point of the inverter 2 is supplied to the load 3. Output from the output point of the inverter 2 and load 3
The AC power supplied to the load 3 contains an unnecessary harmonic component caused by switching, and therefore is supplied to the load 3 via the filter including the inductance LF and the capacitor CF.

Here, the role of connecting the tap of the inductance LT and the connection point N will be described. When the connection point N and the tap are not connected, when the switches Q1 and Q3 of the converter 1 are turned on and the switches Q2 and Q4 are turned off, the potential of the connection point N is about the voltage of the capacitor CA from the neutral point potential of the power source E. Down and switch Q1,
When Q3 is off and the switches Q2 and Q4 are on, the potential at the connection point N is about the capacitor CB from the neutral point potential of the power source E.
Voltage rises. Therefore, due to the high-frequency switching operation of the converter 1, a high-frequency voltage is generated between the neutral point of the power source E or the tap of the inductance LT and the connection point N. Therefore, the voltage between the neutral point on the power source E side and the connection point N fluctuates significantly due to switching. In order to suppress this fluctuation, the tap and the connection point N are connected. That is, since the connection point N is connected to the tap, the voltage between the neutral point of the input power source side and the DC power lines 7 and 8 does not fluctuate significantly due to the switching operation of the switches Q1-Q4 of the converter 1. . Furthermore, the voltage between the neutral point of the load 3 and the neutral point on the side of the power source E is hardly disturbed by the switching of the converter 1. Therefore, the voltage between the neutral point on the load 3 side and the neutral point on the power supply E side is hardly affected by the switching of the converter 1. As a result, it works very effectively in reducing the interference noise to the load 3 and other electronic devices.

Next, the roles of the reactors L1 and L2 will be described. If there is no reactor L1 or L2,
Due to the high-frequency switching operation of the converter 1, an excessive high-frequency current is generated via the connection line PN that connects the tap of the inductance LT and the connection point N. As a result, an excessive high-frequency current flows through the switches Q1-Q4, which leads to the destruction of these switches Q1-Q4. However, as shown in FIG. 1, by connecting the reactors L1 and L2 to the power line, the excessive high-frequency current flowing through the connection PN is effectively suppressed by the reactors L1 and L2, and the destruction of the switches Q1-Q4 is prevented. Avoided.

Next, the role of connecting the connection point N and the connection point M will be described. When the connection point N and the connection point M are not connected, the voltage between the connection point N and the connection point M fluctuates sharply due to the switching operation of the inverter 2. This fluctuation causes a great deterioration in the electromagnetic environment of the load, and induces a large amount of electrical interference noise in the load. In order to suppress the deterioration of the electromagnetic environment, the tap and the connection point M are connected. Since the connection point M and the connection point N are connected, the switching of the inverter 2 does not adversely affect the voltage, and the voltage between the connection point M and the connection point N becomes stable. That is, the potential of the connection point M does not fluctuate drastically due to the switching of the inverter 2, and it is possible to suppress a large amount of electrical interference noise from being applied to the load.

FIG. 3 is an electric circuit showing a second embodiment of the power supply device. In the embodiment shown in FIG. 3, the inductance LT shown in FIG. 1 is removed, and a pair of AC power lines of a three-wire type power source E0 is connected to power source terminals T1 and T2 instead of the power source E of FIG. In addition, the neutral wire of the three-wire type power source E0 is connected to the neutral point terminal of the power supply device, and the neutral point terminal P is connected to the connection point N via the connection line PN. Is the same as.

Now, the role of connecting the neutral point terminal P and the connection point N will be described. When the connection point N and the neutral point terminal P are not connected, the switch Q of the converter 1
When 1 and Q3 are turned on and switches Q2 and Q4 are turned off, the potential of the connection point N is lowered by about the voltage of the capacitor CA from the neutral potential of the power source E0, and the switches Q1 and Q3 are turned on.
When the switch is turned off and the switches Q2 and Q4 are turned on, the potential of the connection point N rises from the neutral point potential of the power source E0 by about the voltage of the capacitor CB. Therefore, due to the high frequency switching operation of the converter 1, a high frequency voltage is generated between the neutral point terminal P and the connection point N. Therefore, the voltage between the neutral point terminal P and the connection point N fluctuates greatly due to switching. In order to suppress this fluctuation, the neutral point terminal P and the connection point N are connected. That is, since the connection point N is connected to the neutral point terminal P, the voltage between the neutral point on the power source E side and the DC power lines 7 and 8 is caused by the switching operation of the switches Q1-Q4 of the converter 1. Does not fluctuate significantly. Furthermore, the neutral point of the load 3 and the power source E
The voltage to and from the neutral point on the side is not disturbed by the switching of the converter 1. Therefore, the voltage between the neutral point of the load 3 and the neutral point on the side of the power source E is hardly or not affected by the switching of the converter 1. As a result, it works very effectively in reducing the interference noise to the load 3 and other electronic devices.

Next, the roles of the reactors L1 and L2 will be described. If there is no reactor L1 or L2,
Due to the high frequency switching operation of the converter 1, an excessive high frequency current is generated via the connection line PN connecting the neutral point terminal P and the connection point N. As a result, an excessive high-frequency current flows through the switches Q1-Q4, and these switches Q1-Q4
Leading to the destruction of. However, as shown in FIG. 3, by connecting the reactors L1 and L2 to the power line,
Excessive high frequency current flowing through the connection PN is the reactor L1,
L2 effectively suppresses the destruction of the switches Q1-Q4.

The present invention is not limited to the particular embodiment of FIGS. 1 and 3 and many variations and modifications are possible. That is, a person skilled in the art can realize various other embodiments without departing from the spirit and scope of the inventive idea by using another uninterruptible power supply device having a more complicated or simpler structure. it can. For example, the inverters and converters are not limited to the illustrated embodiment, and the above-described invention can be implemented by using inverters and converters having other structures. Furthermore, the input power supply is not limited to a single-phase power supply, but can be easily applied to a three-phase power supply, especially a four-wire three-phase power supply.

[0017]

As described above, according to the present invention, the tap of the tap inductance connected in parallel to the power supply terminal, or the neutral point terminal, and the first and second series connected to the output side of the converter. By connecting to the connection point of the capacitor, the adverse effect of the switching of the converter on the electromagnetic environment of the load is effectively suppressed. Further, by connecting the connection point of the third and fourth capacitors connected in series to the output side of the inverter connected to the output side of the converter and the connection point of the first and second capacitors, the load The potential fluctuation of the neutral point was suppressed and the electromagnetic environment of the load was improved. Furthermore, the tap of the tap inductance connected in parallel to the power supply terminal or the neutral point terminal, the connection point of the first and second capacitors connected in series to the output side of the converter, and the output side of the converter. By connecting the output side of the connected inverter to the connection point of the third and fourth capacitors connected in series, the potential fluctuation of the neutral point of the load was suppressed. As a result, it is possible to use the direct transfer circuit without using the insulating transformer on the output side. As a result, it is possible to reduce electrical interference noise to the load without relying on the insulating transformer, eliminate the loss due to the insulating transformer, and provide an uninterruptible power supply suitable for downsizing and weighting, and a power feeding method thereof.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Converter 2 Inverter 3 Load 4 Direct transmission circuit E, E0 power supply LT Inductance with center tap

Claims (7)

[Claims] 1. An uninterruptible power supply device for supplying electric power to a load, comprising: a pair of power supply terminals, a tapped inductance connected in parallel between the pair of power supply terminals, and a pair of input terminals of the pair of power supply terminals. A converter connected to a power supply terminal, and first and second serially connected output sides of the converter
And an inverter connected to the output side of the converter, the connection point of the first capacitor and the second capacitor and the tap of the tapped inductance are connected. Power supply. 2. An uninterruptible power supply device for supplying electric power to a load, comprising: a pair of power supply terminals, a neutral point terminal, a converter having a pair of input terminals connected to the pair of power supply terminals, and the converter. First and second connected in series to the output side of the
Power supply device, comprising: a capacitor and an inverter connected to the output side of the converter, and connecting the connection point between the first capacitor and the second capacitor and the neutral point terminal. . 3. The uninterruptible power supply according to claim 1, further comprising inserting a pair of reactors in a power supply line between the power supply terminal and the converter to connect the connection point and the tap. A power supply device characterized by suppressing an excessive current flow between them. 4. An uninterruptible power supply for supplying power to a load, comprising a pair of power supply terminals, a neutral point terminal, a converter connected to the power supply terminals, and a series connection to the output side of the converter. First and second
Capacitor and an inverter connected to the output side of the converter, connecting the connection point of the first capacitor and the second capacitor and the neutral point terminal, and the power supply terminal and the A power supply device, which is connected to a converter via a pair of reactors. 5. An uninterruptible power supply according to claim 1, further comprising a third output connected to the output side of the inverter.
And a series circuit including a fourth capacitor, and a pair of reactors inserted in a pair of power lines between the inverter and the series circuit including the third and fourth capacitors, and the first capacitor, An uninterruptible power supply device characterized in that a connection point with the second capacitor and a connection point with the third capacitor and the fourth capacitor are connected. 6. The uninterruptible power supply according to claim 2, further comprising a third power supply connected to the output side of the inverter.
And a series circuit including a fourth capacitor, and a pair of reactors between the inverter and the series circuit including the third and fourth capacitors, the connection between the first capacitor and the second capacitor An uninterruptible power supply device characterized in that a point and a connection point of the third capacitor and the fourth capacitor are connected. 7. An uninterruptible power supply according to claim 4, further comprising a third output connected to the output side of the inverter.
And a series circuit including a fourth capacitor, and a pair of reactors between the inverter and the series circuit including the third and fourth capacitors, the connection between the first capacitor and the second capacitor An uninterruptible power supply device characterized in that a point and a connection point of the third capacitor and the fourth capacitor are connected.