JPH06292369A - Uninterruptible power supply device - Google Patents

Abstract

PURPOSE:To effectively suppress a harmful influence to the electromagnetic environment of a load due to the switching of a converter by connecting the tap of a tap inductance connected to a power supply terminal in parallel to the connection point between first and second capacitors connected to the output side of the converter in series. CONSTITUTION:Smoothing capacitors CA and CB are connected to the DC output terminal of a converter 1A in series and a connection point N is connected to the tap of an inductance LT. When switches Q1, Q3, and Q5 and switches Q2, Q4, and Q6 of a converter 1 are turned on or off each other, the potential of the connection point N falls or rises from the neutral-point potential of a power supply E3 by the voltage of the capacitors CA and CB, respectively, thus generating a high-frequency voltage between the tap of an inductance L and the connection point N, causing the voltage between the neutral point on the side of the power supply E3 and the connection point N to fluctuate greatly, and hence suppressing the fluctuation by connecting the connection point N to the tap.

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, a multi-phase AC power supply E3 is connected to power supply terminals TU, TV, TW of the uninterruptible power supply. Six bridge-connected switches Q1, Q2, Q3, Q
The AC input terminal of the converter 1A composed of 4, Q5 and Q6 is connected to the power source terminal T via the reactors LU, LV and LW.
Connected to U, TV, TW. Each switch Q1, Q2
Q3, Q4, Q5 and Q6 are composed of power MOSFETs having a freewheeling diode built therein. Converter 1A
Is for converting AC power to DC power. Each of the switches Q1 to Q6 of the converter 1A is ON / OFF controlled by a control circuit (not shown), thereby controlling the DC voltage of the output of the converter 1A. Between the pair of power lines 7 and 8 connected to the DC output terminal of the converter 1A, a smoothing capacitor C, an inverter 2A and a power source for backup of power failure, that is, a storage battery B as an emergency energy supply source is connected. Normally, the storage battery B is charged by the AC power source E3. When the AC power source E3 fails, the energy stored in the storage battery B is supplied to the inverter 2. The inverter 2A includes six switches S1, S2, S3, S4, S5 and S6 which are bridge-connected.
Each of the switches S1, S2, S3, S4, S5 and S6 is composed of a power MOSFET having a freewheeling diode built therein. The inverter 2A PWM switches S1-S6
By controlling the current, a constant-frequency constant-voltage flowing power is output. The AC output terminal of the inverter 2A is
Reactor LX, LY, LZ and capacitors CX, CY,
It is connected to the load 3A via a filter circuit composed of CZ and a transformer TA. Further, in FIG. 2, the direct feed circuit 4 is connected between the power supply terminals TU, TV, TW and the load 3A. The direct feed circuit 4 switches the power supply to the load 3A from the inverter 2A side to the commercial power source E3 side when the rush current of the load 3A or overload occurs.

Here, the conventional problems will be described.
When the switches Q1, Q3, Q5 of the converter 1A are turned on and the switches Q2, Q4, Q6 are turned off, the potential of the power line 7 becomes substantially equal to the neutral point potential of the power source E3, and
Switches Q1, Q3, Q5 are off, switches Q2, Q
When Q4 and Q6 are turned on, the potential of the power line 8 becomes substantially equal to the neutral point potential of the power source E3. Therefore, conventionally, the voltage between the neutral point potential of the power source EA and the neutral point potentials of the DC power lines 7 and 8 fluctuates greatly due to the switching operation of the switches Q1 to Q6 of the converter 1A.
Due to this fluctuation, disturbance noise is induced in other electronic devices through stray capacitances of the DC lines 7 and 8 and pollutes the electromagnetic environment. Further, this fluctuation deteriorates the electromagnetic environment of the load 3A through the drift capacitance between the primary and secondary windings of the inverter 2A and the transformer TA.

Further, another problem will be described. Normally, in an uninterruptible power supply device equipped with the direct feed circuit 4, an insulating transformer TA is used in its output section. The insulating transformer TA suppresses a large circulating current that circulates through the converter 1A, the inverter 2A, and the direct transfer 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 TA is expensive and very heavy in mass, and also causes losses.

[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 of a polyphase power supply to a load, the power supply terminal and a tap connected in parallel between the power supply terminals. An inductor, a converter having an input terminal connected to a power supply terminal, first and second capacitors serially connected to the output side of the converter, and an inverter connected to the output side of the converter. The connection point between the capacitor and the second capacitor is connected to the tap of the tapped inductance. The invention according to claim 2 is an uninterruptible power supply for supplying electric power of a multiphase power supply to a load, the power supply terminal, a neutral point terminal,
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. The connection point with the capacitor and the neutral point terminal are connected. Claim 3
The invention according to claim 1 is the invention according to claim 1, further comprising:
A filter capacitor including a filter capacitor connected to the power line on the output side of the inverter and a reactor inserted in each power line between the inverter and the filter capacitor, and a connection point between the first capacitor and the second capacitor and a filter capacitor. And a connection point with. The invention according to claim 4 is the invention according to claim 2,
Further, a filter capacitor connected to the output power line of the inverter, a reactor is included between the inverter and the filter capacitor, and a connection point between the first capacitor and the second capacitor and a connection point between the filter capacitors are connected. To be configured. The invention according to claim 5 is the invention according to claim 2, further comprising: a filter capacitor connected to the output side of the inverter; and a reactor between the inverter and the filter capacitor. It is configured to connect the connection point between the second capacitor and the connection point between the filter capacitors.

[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. Furthermore, by connecting the connection point between the filter capacitors connected 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 potential at the neutral point of the load Suppresses dynamic fluctuations and improves the electromagnetic environment of the load. Furthermore, the tap of the tap inductance connected in parallel to the power supply terminal, or the neutral point terminal, and the first side connected in series to the output side of the converter.
By connecting the connection point of the second capacitor and the connection point of the filter capacitor connected to the output side of the inverter connected to the output side of the converter, the potential fluctuation of the neutral point of the load is 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, a multi-phase AC power supply E3
Are connected to power supply terminals TU, TV, TW. An inductor LT with a center tap is connected between the power supply terminals TU, TV and TW. This inductance L
The windings of T are tightly coupled to each other, and the AC power source E3
The inductance LT has a high impedance with respect to the frequency of and the exciting current flowing through the inductance LT is small. An example of the inductance LT with a center tap is shown in FIG. As shown in FIG. 4, the inductance LT with the center tap is formed on the magnetic core CORE by winding 7
It is composed of A, 7B and 7C. Six bridge-connected switches Q1, Q2, Q
The AC input terminal of the converter 1A composed of 3, Q4, Q5 and Q6 is connected to power supply terminals TU, TV and TW via reactors LU, LV and LW. Each switch Q1, Q
2, Q3, Q4, Q5, Q6 are composed of power MOSFETs with built-in freewheeling diodes. Converter 1
A is for converting AC power into DC power. Each switch Q1 to Q6 of converter 1A is on / off controlled by a control circuit (not shown), and thereby controls the DC voltage of the output of converter 1A. Normally, converter 1A has an input power supply voltage (effective value) of 200 volts, while the output voltage of converter 1A is constantly controlled to a DC voltage of about 350 volts. 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 1A. The connection point N between these capacitors CA and CB is connected to the tap of the inductance LT. Between the power lines 7 and 8, an inverter 2A and an emergency energy supply source, that is, a storage battery B as a power source for power failure backup are further connected. Normally, the storage battery B is charged by the multi-phase AC power source E3. When the multi-phase AC power supply E3 fails, the energy stored in the storage battery B is converted into the inverter 2
Supplied to A. The inverter 2A has switches S1 and S
2, S3, S4, S5 and S6 are bridge-connected. Switches S1, S2, S3, S4, S5, S6
Consists of a power MOSFET with a built-in freewheeling diode. Inverter 2 is 20kH for noise reduction
It has an operating frequency above the audible frequency of about z, performs sine wave modulation, and outputs an alternating voltage of a constant frequency and a constant voltage. The AC power output from the inverter 2A is supplied to the load 3A. Since the AC power output from the inverter 2A and supplied to the load 3A includes unnecessary harmonic components due to switching, the inductances LX and L
It is supplied to the load 3A via a filter composed of Y and LZ and filter capacitors CX, CY and CZ. A connection point MA and a connection point N connecting the filter capacitors CX, CY and CZ are connected by a connection.

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, the switches Q1, Q3 and Q5 of the converter 1 are turned on and the switches Q2, Q4 and Q are turned on.
When 6 is turned off, the potential of the connection point N drops by about the voltage of the capacitor CA from the neutral potential of the power source E3, and
Switches Q1, Q3, Q5 are off, switches Q2, Q
When Q4 and Q6 are turned on, the potential of the connection point N rises by about the voltage of the capacitor CB from the neutral potential of the power source E3. 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 E3 or the tap of the inductance LT and the connection point N.
Therefore, the voltage between the neutral point on the power source E3 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 to Q6 of the converter 1A. . Furthermore, load 3
The voltage between the neutral point of A and the neutral point of the power supply E3 side is hardly disturbed by the switching of the converter 1A. Therefore, the voltage between the neutral point on the load 3A side and the neutral point on the power supply E3 side is hardly affected by the switching of the converter 1A. As a result, it works extremely effectively in reducing the interference noise to the load 3A and other electronic devices.

Next, the role of connecting the connection point N and the connection point MA will be described. When the connection point N and the connection point MA are not connected, the voltage between the connection point N and the connection point MA fluctuates drastically due to the switching operation of the inverter 2A. 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 MA are connected. Connection point MA and connection point N
Since and are connected, they are not adversely affected by the switching of the inverter 2A, and the voltage between the connection point MA and the connection point N is stable. That is, the potential at the connection point MA does not fluctuate significantly due to the switching of the inverter 2A, 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 the power supply E3 shown in FIG.
Instead, the AC power line of the four-wire multi-phase power supply E30 is connected to the power supply terminals TU, TV, TW, and the neutral wire of the four-wire multi-phase power supply E0 is connected to the neutral point terminal P of the power supply device. And
Further, the neutral point terminal P is connected to the connection point N via a wire connection, and other configurations are the same as those in FIG.

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 1A
When 1, Q3, Q5 are turned on and switches Q2, Q4, Q6 are turned off, the potential of the connection point N is lowered from the neutral point potential of the power source E30 by about the voltage of the capacitor CA, and the switches Q1, Q3, Q5 are turned on. Off, switch Q2, Q4, Q
When 6 is turned on, the potential of the connection point N rises by about the voltage of the capacitor CB from the neutral potential of the power source E30. Therefore, a high-frequency voltage is generated between the neutral point terminal P and the connection point N by the high-frequency switching operation of the converter 1A. 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 to Q6 of the converter 1A. Does not fluctuate significantly. Furthermore, the voltage between the neutral point of the load 3A and the neutral point on the power supply E30 side is not disturbed by the switching of the converter 1A. Therefore, the voltage between the neutral point of the load 3A and the neutral point on the power supply E30 side is hardly or not affected by the switching of the converter 1A. As a result, it works extremely effectively in reducing the interference noise to the load 3A and other electronic devices.

Next, the roles of the reactors LU, LV and LW will be described. If one of reactors LU, LV, and LW is not present, an excessive high-frequency current is generated by the high-frequency switching operation of converter 1A via the connection line between neutral point terminal P and connection point N. As a result, an excessive high-frequency current flows through the converter 1A, and the switches of the converter 1A are destroyed. However, as shown in FIG.
By connecting reactors LU, LV, and LW to the power line, excessive high-frequency current flowing through the connection is effectively suppressed by reactors LU, LV, and LW, and destruction of the switch of converter 1A is avoided.

Next, the role of connecting the connection point N and the connection point MA will be described. When the connection point N and the connection point MA are not connected, the voltage between the connection point N and the connection point MA fluctuates drastically due to the switching operation of the inverter 2A. 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 MA are connected. Connection point MA and connection point N
Since and are connected, they are not adversely affected by the switching of the inverter 2A, and the voltage between the connection point MA and the connection point N is stable. That is, the potential at the connection point MA does not fluctuate significantly due to the switching of the inverter 2A, and it is possible to suppress a large amount of electrical interference noise from being applied to the load.

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 would be
Alternatively, an uninterruptible power supply having a simpler structure can be used to realize various other embodiments without departing from the spirit and scope of the inventive idea. For example, the multi-phase AC input power supply is not limited to a three-phase power supply, but can be easily applied to an AC power supply of any number of phases such as a six-phase power supply and a twelve-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. Furthermore, by connecting the connection point between the filter capacitors connected 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 potential at the neutral point of the load Suppresses dynamic fluctuations and improves the electromagnetic environment of the load. 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 connection point between the filter capacitors connected to the output side of the connected inverter, 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.

FIG. 4 is a front view showing an inductance with a center tap shown in FIG. 1.

[Explanation of symbols]

 1A converter 2A inverter 3A load 4 direct transfer circuit E3, E30 multi-phase AC power supply LT inductance with center tap

Claims (5)

[Claims] 1. An uninterruptible power supply for supplying electric power of a multi-phase power supply to a load, wherein a power supply terminal, a tapped inductance connected in parallel between the power supply terminals, and an input terminal connected to the power supply terminal. Converter 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 for supplying electric power of a multi-phase power supply to a load, the power supply terminal, a neutral point terminal, a converter having an input terminal connected to the power supply terminal, and an output of the converter. First and second connected in series to the side
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 a filter capacitor connected to the power line on the output side of the inverter, and each power line between the inverter and the filter capacitor. An uninterruptible power supply including an inserted reactor, wherein a connection point between the first capacitor and the second capacitor and a connection point between the filter capacitors are connected. 4. The uninterruptible power supply according to claim 2, further comprising a filter capacitor connected to the output power line of the inverter, and a reactor between the inverter and the filter capacitor. An uninterruptible power supply unit characterized in that a connection point between the capacitor and the second capacitor and a connection point between the filter capacitors are connected. 5. The uninterruptible power supply according to claim 4, further comprising a filter capacitor connected to the output side of the inverter, and a reactor between the inverter and the filter capacitor, And a connection point between the first capacitor and the second capacitor are connected.