JPH0956085A - Uninterruptible power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of an uninterruptible power unit and to improve the efficiency of the unit by using a capacitor as an energy storing element and connecting a battery to the capacitor as a backup element. SOLUTION: The voltage of a capacitor 8 is set to a high value when an uninterruptible power unit is operated. When an AC input power source 1 runs down, the voltage of the capacitor 8 drops and, when the voltage of the capacitor 8 approaches the voltage of a battery 12, the body diode of the switching element 111 of a charging and discharging circuit 11 is conducted and electric power is supplied to the output of the power unit from the battery 12. When the voltage of the capacitor 8 drops to the voltage of the battery 12, the conduction loss which occurs when the battery is backed up can be reduced by turning on the switching element 111. In addition, the battery 12 can be charged while the voltage across the output terminals 61 and 62 connected to a rectifying and smoothing circuit 5 and the voltage of the capacitor 8 are controlled by turning on/off the switching element 111.

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 having a high input power factor and a reduced output AC frequency ripple.

[0002]

2. Description of the Related Art FIG. 7 shows a prior art example of an uninterruptible power supply system having a high input power factor and a reduced output AC frequency ripple. In the conventional example, the power factor correction circuit B connected to the AC input source A controls the input current to have a sine wave shape. Here, in the output voltage of the power factor correction circuit B, ripples of the AC frequency occur due to the imbalance of the instantaneous power of the AC input and the DC output, so that as shown in FIG. The output voltage was controlled in the DC / DC converter D connected to the subsequent stage of the capacitor C for use to obtain a stable output with reduced ripple.
A battery E for backup at the time of power failure was connected to this output, and was normally floating-charged at the output voltage.

[0003]

DISCLOSURE OF THE INVENTION In the conventional example,
Since the battery E having a voltage equal to the output voltage is required,
When the output voltage is high, it is necessary to connect a plurality of batteries E in series. Further, at the time of backup, the voltage of the battery E decreases with discharge, so that a device or the like for compensating for the voltage decrease is required.

An object of the present invention is to solve the above drawbacks and to provide a compact and highly efficient uninterruptible power supply device.

[0005]

An uninterruptible power supply system according to the present invention comprises an energy storage element, a switching section for controlling the energy stored in the energy storage element,
An AC input power supply device of a system having a switching unit for controlling emission energy from the energy storage element to an output, and obtaining a constant output voltage by controlling stored energy and emission energy of the energy storage element, A capacitor is used as a storage element,
A backup element such as a battery is connected to the capacitor through a charge / discharge circuit.

[0006] Further, it has a discharging circuit constituted by connecting a backup element such as a battery to a capacitor as the energy storage element through a charging circuit and providing a switch element connected from the charging circuit to an output. It is characterized by.

[0007]

In the uninterruptible power supply according to the present invention, the energy provided to increase the power factor of the input and reduce the AC frequency ripple of the output by compensating for the imbalance of the instantaneous power of the AC input and the DC output. By using a storage capacitor and connecting a backup element such as a battery to this capacitor via a charging circuit, it is possible to give a backup function to a high power factor AC input power supply device with a relatively simple configuration. The output voltage can be controlled even during backup. Further, since the voltage of the capacitor can be arbitrarily set according to the voltage of the battery, the capacitor can be efficiently charged, and there are few restrictions on the battery.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit configuration diagram showing a first embodiment corresponding to the invention described in claim 1 of the present invention. As shown in FIG. 1, in this embodiment, a rectifier circuit 2 including a diode connected to an AC input source 1, and a switching unit 3 having a switching element 31 connected to the rectifier circuit 2.
A transformer 4 having an input winding 41 connected to the output of the switching unit 3 and first and second output windings 42 and 43; and a diode 5 connected to the first output winding 42.
Rectifying / smoothing circuit 5 including 1 and output capacitor 52
And an output terminal 61 connected to the rectifying / smoothing circuit 5,
62, a switching circuit 7 connected to the second output winding 43 and having a switching element 71, a capacitor 8 as an energy storage element connected to this switching circuit 7, and an output terminal 6 using this capacitor 8 as an input.
DC / DC converter 9 composed of a step-up chopper including an inductor 91 for supplying electric power to the power supply circuit 1, 62, a switching element 92, and a diode 93, and output terminals 61, 6
The voltage between the two and the voltage of the capacitor 8 are detected, and the switching elements 31 and 71 and the DC / DC converter 9 are detected.
Circuit 10 for controlling the switching element 92 in
And a switching element 11 connected to the capacitor 8
1, a diode 112, an inductor 113, and a charging / discharging circuit 11, and a battery 12 as a backup element connected to the charging / discharging circuit 11.

In this embodiment, the input current becomes a sinusoidal waveform proportional to the input voltage waveform by operating the transformer 4 so that the current flowing through the winding of the transformer 4 becomes discontinuous, thereby increasing the input power factor. Can be realized.

FIG. 2 shows switching elements 31, 71 and 9
An example of the drive voltage waveform of No. 2 is shown. In the circuit of FIG. 1, energy is stored in the transformer 4 during the ON period of the switching element 31, and the excitation energy stored in the transformer 4 is supplied to the output during the simultaneous OFF period of the switching elements 31 and 71. In the charging mode in which the input power is higher than the output power, the capacitor 8 is charged with the energy stored in the transformer 4 during the ON period of the switching element 71. Here, the voltage generated in the first and second output windings 42 and 43 during the simultaneous off period of the switching elements 31 and 71 is equal to the voltage generated in the first and second output windings 4 during the on period of the switching element 71.
It is necessary to set it so that it is higher than the voltage generated at 2, 43. Further, the switching element 71 requires an element (diode D) having a reverse breakdown voltage as shown in FIG. 1 surrounded by a dotted line in the FET. In the discharge mode in which the input power is smaller than the output power, the switching element 92 is also turned on / off to turn on the AC input source 1.
And the electric power is simultaneously supplied from the capacitor 8 to the output. Therefore, the voltage between the output terminals 61 and 62 can be stabilized by controlling the switching element 71 in the charging mode and the switching element 92 in the discharging mode. That is, in the charging mode, the output terminal 61,
The voltage between 62 becomes slightly higher than the reference voltage, the error voltage controls the pulse width of the switching element 71, and the voltage between the output terminals 61 and 62 becomes slightly lower than the reference voltage in the discharge mode. The pulse width of the switching element 92 is controlled by the error voltage. Further, under this control, by controlling the pulse width of the switching element 31, the average value of the voltage of the capacitor 8 in the input AC cycle can be controlled to be constant. Here, the switching element 31 and the switching element 71 need to be turned on / off in synchronization as shown in FIG. 2, but the switching element 92 may not be synchronized.

In this embodiment, the voltage of the capacitor 8 needs to be set higher than the voltage of the battery 12 normally during operation. When the AC input source 1 goes down and the voltage of the capacitor 8 drops to about the voltage of the battery 12, the body diode of the switching element 111, which is a MOSFET, becomes conductive, and power is supplied from the battery 12 to the output. Here, when the voltage of the capacitor 8 drops to the voltage of the battery 12, the switching element 11
By turning on 1, the conduction loss at the time of battery backup can be reduced. Further, by turning on / off the switching element 111, the battery 12 can be charged while controlling the voltage between the output terminals 61 and 62 and the voltage of the capacitor 8 described above.

FIG. 3 is a circuit configuration diagram showing a second embodiment corresponding to the invention described in claim 1 of the present invention. As shown in FIG. 3, in the present embodiment, the rectifier circuit 2 including a diode connected to the AC input source 1, the inductor 13 having the primary winding 131 and the secondary winding 132 connected to the rectifier circuit 2. And a switching unit 3 including switching elements 31 and 32 connected to the primary winding 131.
A rectifying / smoothing circuit including a transformer 4 having an input winding 41 and an output winding 42 connected to the output of the switching unit 3, and diodes 51 and 53 and an output capacitor 52 connected to the output winding 42. 5 and this rectification
Output terminals 61 and 62 connected to the smoothing circuit 5, a capacitor 8 connected to the secondary winding 132 of the inductor 13 via a diode 72, and power supplied to the output terminals 61 and 62 using the capacitor 8 as an input. Inductor 91,
A DC / DC converter 9 composed of a step-up chopper composed of a switching element 92 and a diode 93, a current flowing through a primary winding 131 of the inductor 13, a voltage of the output terminals 61 and 62, and a voltage of a capacitor 8 are detected. A control circuit 10 for controlling the switching elements 31, 32, 92 in the switching section 3 and the DC / DC converter 9, a switching element 111 connected to the capacitor 8, a diode 112, an inductor 1
The charging / discharging circuit 11 is composed of 13 and the battery 12 connected to the charging / discharging circuit 11.

FIG. 4 shows switching elements 31, 32, 9
An example of the drive voltage waveform of No. 2 is shown. In the circuit of FIG. 3, energy is stored in the inductor 13 during the ON period of the switching element 31, and electric power is supplied to the output through the transformer 4 during the ON period of the switching element 32. In the charging mode in which the input power is larger than the output power, part of the energy stored in the inductor 13 during the simultaneous off period of the switching elements 31 and 32 is charged in the capacitor 8 via the diode 72. In the discharge mode in which the input power is smaller than the output power, the switching element 92 is also turned on / off to supply power from the AC input source 1 and the capacitor 8 to the output at the same time. Therefore, the output terminal 6
The voltage between 1 and 62 can be stabilized by controlling the simultaneous off period of the switching elements 31 and 32 in the charge mode and the on period of the switching element 92 in the discharge mode. That is, in the charge mode, the voltage between the output terminals 61 and 62 becomes slightly higher than the reference voltage, and the error voltage controls the pulse width of the switching elements 31 and 32 during the simultaneous off period. The voltage between 61 and 62 becomes slightly lower than the reference voltage, and the error voltage controls the pulse width of the switching element 92.

In the present embodiment, the switching element is so arranged that the current flowing in the primary winding 131 of the inductor 13 is detected and the average value of this current in the switching cycle follows a sinusoidal reference waveform synchronized with the input voltage. 31
The input power factor can be increased by controlling the ON period of. Further, by controlling the amplitude of the sinusoidal reference waveform, the average value of the voltage of the capacitor 8 in the input AC cycle can be controlled to be constant.

The circuit operation at the time of backup and charging in this embodiment can be realized similarly to the circuit of FIG.

The step-up chopper portion constituting the DC / DC converter 9 shown in FIGS. 1 and 3 can be similarly constructed as a step-down chopper or a step-up / step-down chopper. Also,
The present invention can be realized in the same manner even if the switching unit 3 of FIG. 3 has a push-pull or full bridge configuration.

FIG. 5 is a circuit configuration diagram showing a first embodiment corresponding to the invention described in claim 2 of the present invention. As shown in FIG. 5, in this embodiment, the rectifier circuit 2 including a diode connected to the AC input source 1, and the switching unit 3 including the switching element 31 connected to the rectifier circuit 2.
A transformer 4 having an input winding 41 connected to the output of the switching section 3 and first and second output windings 42 and 43; a diode 51 connected to the first output winding 42; Rectifying / smoothing circuit 5 including output capacitor 52, and output terminal 6 connected to this rectifying / smoothing circuit 5.
1, 62, a switching circuit 7 having a switching element 71 connected to the second output winding 43, a capacitor 8 as an energy storage element connected to the switching circuit 7, and the capacitor 8 as an input. Inductor 9 for supplying power to the output terminals 61, 62
1, a DC / DC converter 9 including a step-up chopper including a switching element 92 and a diode 93, a voltage between the output terminals 61 and 62, and a voltage of the capacitor 8 are detected to detect the switching elements 31 and 71, Control circuit 10 for controlling switching element 92 in DC / DC converter 9, switching elements 141 and 142 connected to capacitor 8, and inductor 14
3, a charging circuit 14 including three, a battery 12 connected to the charging circuit 14, and a diode 15 connected to the inductor 143 and the switching element 142 to form a discharging circuit from the battery 12 to an output. Is.

FIG. 6 is a circuit configuration diagram showing a second embodiment corresponding to the invention described in claim 2 of the present invention. As shown in FIG. 6, in this embodiment, a rectifier circuit 2 including a diode connected to the AC input source 1, an inductor 13 having a primary winding 131 and a secondary winding 132 connected to the rectifier circuit 2. And a switching unit 3 including switching elements 31 and 32 connected to the primary winding 131.
And an input winding 41 connected to the output of the switching unit 3.
And a transformer 4 having an output winding 42, diodes 51 and 53 and a capacitor 52 connected to the output winding 42.
A rectifying / smoothing circuit 5 including the output terminals 61 and 62 connected to the rectifying / smoothing circuit 5, and the inductor 13
Of the secondary winding 132 of the capacitor 8 via the diode 72, and the inductor 9 connected to the secondary winding 132 of the capacitor 8 as an input to supply power to the output terminals 61 and 62.
1, a DC / DC converter 9 composed of a step-up chopper including a switching element 92 and a diode 93, a current flowing through the primary winding 131 of the inductor 13, the voltage of the output terminals 61 and 62, and the voltage of the capacitor 8. A control circuit 10 for detecting and controlling the switching elements 31, 32, 92 in the switching unit 3 and the DC / DC converter 9, a charging circuit 14 including switching elements 141, 142 connected to the capacitor 8 and an inductor 143, The battery 12 is connected to the charging circuit 14, and the diode 15 is connected to the inductor 143 and the switching element 142 and constitutes a discharging circuit from the battery 12 to the output.

In the embodiment of FIGS. 5 and 6, the battery 12 is charged by turning on / off the switching element 141. Further, by turning on / off the switching element 142, electric power can be directly supplied from the battery 12 to the output. Other operations and control of each switching element in the circuits of FIGS. 5 and 6 are the same as those of the circuits of FIGS. 1 and 3, respectively, but since the capacitor 8 is not used during backup, the battery 12 outputs more efficiently to the output. Can supply power.

[0021]

As described above, according to the present invention,
In an AC input power supply device of a system that obtains a constant output voltage by controlling stored energy and released energy of an energy storage element, a backup element such as a battery is connected to a capacitor as the energy storage element via a charging circuit, The output voltage can be controlled even during backup by using the charging circuit also as a discharging circuit or by configuring a discharging circuit that directly supplies the output from the charging circuit, and the voltage of the capacitor can be arbitrarily set. Since it can be charged efficiently, it is possible to configure a small, highly efficient, and high power factor uninterruptible power supply.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment corresponding to the invention described in claim 1 of the present invention.

FIG. 2 is a diagram showing an example of a drive voltage waveform of a switching element according to the embodiment of FIG.

FIG. 3 is a circuit configuration diagram showing a second embodiment corresponding to the invention described in claim 1 of the present invention.

FIG. 4 is a diagram showing an example of a drive voltage waveform of a switching element according to the embodiment of FIG.

FIG. 5 is a circuit configuration diagram showing a first embodiment corresponding to the invention described in claim 2 of the present invention.

FIG. 6 is a circuit configuration diagram showing a second embodiment corresponding to the invention described in claim 2 of the present invention.

FIG. 7 is a configuration diagram showing a conventional high power factor uninterruptible power supply.

[Explanation of symbols]

 1 AC Input Source 2 Rectifier Circuit 3 Switching Unit 31 Switching Element 32 Switching Element 4 Transformer 41 Input Winding 42 First Output Winding 43 Second Output Winding 5 Rectifying / Smoothing Circuit 51 Diode 52 Output Capacitor 53 Diode 61 Output Terminal 62 Output terminal 7 Switching circuit 71 Switching element 72 Diode 8 Capacitor 9 DC / DC converter 91 Inductor 92 Switching element 93 Diode 10 Control circuit 11 Charge / discharge circuit 111 Switching element 112 Diode 113 Inductor 12 Battery 13 Inductor 131 Primary winding 132 Two Next winding 14 Charging circuit 141 Switching element 142 Switching element 143 Inductor 15 Diode

Claims (2)

[Claims] 1. An energy storage device comprising: an energy storage device; a switching unit for controlling energy stored in the energy storage device; and a switching unit for controlling emission energy from the energy storage device to an output. In an AC input power supply device of a method of obtaining a constant output voltage by controlling stored energy and released energy, a capacitor is used as the energy storage element, and a backup element is connected to the capacitor through a charge / discharge circuit. And an uninterruptible power supply. 2. An energy storage element, a switching unit that controls energy stored in the energy storage element, and a switching unit that controls energy emitted from the energy storage element to an output. In an AC input power supply device of a method of obtaining a constant output voltage by controlling stored energy and released energy, a capacitor is used as an energy storage element, and a backup element is connected to the capacitor via a charging circuit, An uninterruptible power supply device having a discharge circuit configured by providing a switch element connected to an output.