JP2001008462A - Uninterruptible power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an external load from a rush current at start and supply power to a capacitive external load of high power factor. SOLUTION: At start up, a power supply device 10 connects an inverter 18 among the inverter 18 and a bypass circuit 11 to an external load, and further causes soft start of the inverter to take place, so as to have the effective value of the output voltage elevated gradually by a control circuit 19. With this constitution, an external load is protected from a large rush current. Furthermore, as an AC voltage outputted from the inverter 18 has a trapezoidal waveform, even if a capacitive external load is connected, a reactive current is suppressed and a power factor can be improved.

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 capable of continuously supplying power to an external load by an inverter using a storage battery even when an external AC power supply fails.

[0002]

2. Description of the Related Art Conventionally, as this type of uninterruptible power supply,
The one disclosed in JP-A-6-105483 shown in FIG. 6 is known. In the figure, an uninterruptible power supply includes a rectifier 1, a storage battery 2, an inverter 3, a switch 4,
A commercial power supply is connected to an input terminal 6 of the uninterruptible power supply, and an external load is connected to an output terminal 7 of the uninterruptible power supply. When the uninterruptible power supply is started, the changeover switch 4 connects the bypass circuit 5 to an external load, and the AC voltage output from the commercial power supply is directly applied to the external load. Then, after the inverter 3 normally starts up and is synchronized with the commercial power supply, the switch 4 is operated,
The bypass circuit 5 is disconnected from the external load and the inverter 3 is connected to the external load, so that the inverter 3 supplies power to the external load.

[0003]

However, in the above-described conventional uninterruptible power supply, the bypass circuit 5 is activated at the time of startup.
Therefore, there is a problem that a large inrush current can be given to the external load from the external device. As another problem, inverters have been developed with the technical task of making the output voltage waveform closer to a sine wave, but when a capacitive load is connected, a large amount of reactive current flows and the power factor decreases. There is a problem of lowering.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide an uninterruptible power supply capable of preventing an inrush current from flowing into an external load at startup. The second purpose is to provide a capacitive external load,
An object of the present invention is to provide an uninterruptible power supply capable of supplying power at a high power factor.

[0005]

According to a first aspect of the present invention, there is provided an uninterruptible power supply having a rectifier connected to an external AC power supply and / or an inverter receiving power from a storage battery and outputting an AC voltage. And an inverter control means for supplying power from the inverter at the start of power supply to the external load and gradually increasing the effective value of the output voltage to perform a soft start.

A second aspect of the present invention is characterized in that, in the first aspect, the inverter control means changes the output voltage waveform of the inverter to a trapezoidal waveform.

According to a third aspect of the present invention, there is provided an uninterruptible power supply.
An uninterruptible power supply including an inverter that receives power from a rectifier connected to an external AC power supply and / or outputs an AC voltage by receiving power from a storage battery, includes trapezoidal wave generation means for converting the AC voltage waveform output from the inverter into a trapezoidal waveform. However, it has features.

According to a fourth aspect of the present invention, in the first aspect of the invention, there is provided a bypass circuit for directly or transforming and outputting an AC voltage received from an external AC power supply, and an abnormality in the operation of the inverter. Switching means for switching the output so that the power supply from the inverter is cut off and power supply from the bypass circuit is provided when the power supply occurs.

The uninterruptible power supply of claim 1 is
At the time of startup, since the inverter and the bypass circuit supply power to the external load from the inverter, and the inverter is so-called soft-started by the inverter control means so that the effective value of the output voltage gradually increases.
Inrush current can be prevented from flowing to the external load.

According to the second and third aspects of the present invention, since the AC voltage waveform output from the inverter is trapezoidal, even if a capacitive load is connected, the reactive current is suppressed and the power factor is improved. be able to. This uninterruptible power supply is particularly preferable as an uninterruptible power supply for an amplifier on a CATV transmission line, and is particularly preferable when the amplifier is a capacitive load. Suitable for.

According to the configuration of claim 4, power is supplied from the bypass circuit even when the inverter is out of order, so that the reliability as a power supply can be improved. When a bypass circuit is provided, it is preferable that the output from the bypass circuit and the output from the inverter always have the same phase. By doing so, a phase shift does not occur at the time of switching, and there is no need to align the phases again at the time of switching. Furthermore, to ensure that the phase of the output from the bypass circuit and the phase of the output from the inverter are always aligned, the phase of the inverter output is aligned with the phase of the external AC power source, and the phase of the bypass circuit output is, for example, The received AC voltage may be directly or transformed and output to make the phase of the external AC power supply uniform.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS. A power line L1 (see a bold line in FIG. 1) provided in an uninterruptible power supply 10 (hereinafter, appropriately referred to as “power supply 10”) of the present embodiment is branched into a bypass circuit 11 and an AC generation circuit 12 on the input side. Have been. A commercial power supply (not shown) as an external AC power supply of the present invention is connected to the input terminal 15 of the power line L1. This is a transformer coil (not shown) provided at a branch portion between the bypass circuit 11 and the AC generation circuit 12. As a result, AC1
The voltage is reduced from 00 V to, for example, 60 V, and both circuits 11, 12
, And the bypass circuit 11 outputs the AC power as it is.

On the other hand, the AC generation circuit 12 includes a rectifier 16, an inverter 18, and a storage battery 17, and the inverter 18
Receives DC power from at least one of the rectifier 16 and the storage battery 17, converts the DC power into AC power, and outputs the AC power.

An output switch 13 for selectively connecting the output of the inverter 18 and the output of the bypass circuit 11 to the output terminal 14 of the power supply 10 is provided on the output side of the power line L1 of the power supply 10. I have. The output changeover switch 13 always connects the inverter 18 to the output terminal 1.
4 when the inverter 18 detects an abnormality as described later, the bypass circuit 11 is connected to the output terminal 1.
Connect to 4.

The output changeover switch 13 and the inverter 18 are both controlled by a control circuit 19 provided in the power supply 10. As shown in FIG. 2, the control circuit 19
The signal generation circuit 22 includes a triangular wave generation circuit 23 and a reference wave generation circuit 21 in series.

The reference wave generation circuit 21 is shown in detail in FIG.
A total of eight resistors 31 are connected in parallel to the minus input of the resistor 31. These resistors 31 are connected to a multiplexer 32 to selectively apply a bias voltage VC1 to one of the resistors 31 group.
Is applied. The group of resistors 31 is, for example,
In the figure, the resistance values of the third to third resistors 31 from the bottom are different so as to increase in order from the bottom, and the remaining 5
Each of the three resistors 31 has the same resistance value. Also,
An inverting switch circuit 33 is provided at a stage subsequent to the inverting amplifier 30, and a smoothing capacitor (not shown) is provided at a subsequent stage. And the multiplexer 32
Is a resistor 31 based on a count signal from a count circuit 34 for counting the synchronization pulse given from the CPU 24.
Activate one of the groups.

The output of the commercial power supply and the output of the inverter 18 are supplied to the CPU 24 by a phase comparator 25.
A and 25B are input as pulse signals.
The output voltage of the inverter 18 is taken into the error amplifier circuit 26 through the notch filter 27. The error amplification circuit 26 is shown in the lower part of FIG.
An error voltage between the taken-in output voltage of the inverter 18 and the reference voltage Vrf is inverted and amplified, and output as a bias voltage VC1 of the reference wave generation circuit 21.

A soft start circuit 28 is connected to the output side of the error amplification circuit 26. The soft start circuit 28 is shown in the upper part of FIG.
CR integrating circuit 35 that operates based on a signal from U24
Is non-inverted amplified by an operational amplifier 37. The output side of the operational amplifier 37 is connected to the cathode of a diode D1, and the anode of the diode D1 is connected to the output of the error amplifier circuit 26.

The control circuit 19 includes an inverter 18
And an output of the PWM signal generation circuit 22 to detect an abnormality of the inverter 18. The inverter abnormality detection circuit 40 drives the output switch 13 when detecting an abnormality of the inverter 18.

The operation of the power supply device 10 having the above configuration will be described below. For example, a CATV (cable television) is connected to an output terminal 14 of the power supply device 10 as an external load.
Relay amplifiers arranged at predetermined intervals along a cable for connection. This relay amplifier is, for example, AC60V
It has an input switching power supply and becomes a capacitive load when viewed from the power supply side. The output switch 13 of the power supply 10 connects the output of the inverter 18 to the output terminal 14 of the power supply 10.

When the start switch of the power supply 10 is turned on, the control circuit 19 and the rectifier 16 start up. Next, the control circuit 19 starts up the inverter 18 by operating as follows. That is, in the control circuit 19, the CPU 2
4, a synchronization pulse is sent to a counter circuit 34 provided in the reference wave generation circuit 21. Based on a 3-bit count signal from the circuit 34, the multiplexer 32 sequentially transmits the respective resistors 31 from the lower side of FIG. The switching is performed so that the bias voltage VC1 is applied to the first line. Here, the resistance values of the respective resistors 31 are different so as to increase in order from the bottom to the third from the bottom in the same figure, and the other resistors 31 have the same resistance value. The amplification factor of the inverting amplifier 30 to which the resistor 31 is connected in parallel is changed in the order of “increases in steps”, “maintains the same magnitude for a certain period”, and “decreases in steps”. This is repeated every half cycle of the AC to be output by the inverter 18. As a result, a pulsating voltage having a waveform like a series of a plurality of trapezoids each having a stepwise hypotenuse is output from the inverting amplifier 30. Further, a signal is sent from the counter circuit 34 to the inverting switch circuit 33 every half cycle of the alternating current to be output from the inverter 18, and the above-mentioned plural trapezoids are inverted every other one. Smooth with a capacitor. As a result, the trapezoidal AC voltage that changes in an inclined manner before and after the zero-cross phase as shown in FIG. Is output.

The PWM signal generation circuit 22 generates a drive signal that has been subjected to pulse width modulation as known in the art from the reference wave and the triangular wave of, for example, 20 KHz output from the triangular wave generation circuit 23. The switches provided in the main circuit of the inverter 18 are turned on and off based on the drive signal. Thus, the inverter 18
PWM control is performed, and a PWM wave corresponding to the reference wave is output. Here, the effective value of the PWM wave corresponds to the wave height of the reference wave.
Corresponds to the bias voltage V C1 applied to the

In this embodiment, the reference wave generation circuit 2
2 and FIG. 4 are connected to the input line of the bias voltage VC1 of FIG.
As shown in FIG. 2, the soft start circuit 28, the error amplification circuit 26, and the output line are connected in common, and as described in detail below, when the power supply 10 starts, the bias voltage VC1 of the reference wave generation circuit 21 gradually increases. After the voltage is boosted and the operation becomes steady, the bias voltage VC1 is feedback-controlled so that the output voltage of the inverter 18 (the detected voltage corresponding thereto) matches the reference voltage Vrf.

Hereinafter, this will be described in order from the start of the power supply device 10. First, immediately after the power supply device 10 is started, the transistor 36 provided in the soft start circuit 28
It is turned on in response to a signal from 24. Therefore, a value obtained by dividing the power supply voltage VCC by the resistors R1 and R2 is applied to the non-inverting input terminal of the operational amplifier 37 of the soft start circuit 28.

On the other hand, since the inverter 18 is not operating immediately after the power supply device 10 is started, the output of the error amplifier circuit 26 tends to reach the maximum value. However, since the resistors R1, R2 and the like are set so that the output level of the operational amplifier 37 of the soft start circuit 28 becomes lower than the maximum value, the diode D1 is turned on in a forward bias state, and the error amplifier circuit is turned on. The output voltage of the soft start circuit is suppressed to be substantially equal to the output voltage of the operational amplifier 37 of the soft start circuit. Therefore, the initial voltage determined by the resistors R1 and R2 of the soft start circuit 28 is given to the reference wave generation circuit 21 as the bias voltage VC1.

Thereafter, it is assumed that a power supply start operation to the load is performed. Then, a synchronization pulse is output from the CPU 24 to start generation of the PWM signal, the inverter 18 starts operating, and the transistor 36 is turned off by the signal from the CPU 24. At this point, since the bias voltage VC1 applied to the reference wave generation circuit 21 is an initial voltage and low, the reference wave applied to the PWM signal generation circuit 22 is, for example, as shown in the waveform diagram a of FIG. The trapezoidal wave has a low peak value, and thus the effective value of the AC voltage output from the inverter 18 is low.

After the transistor 36 is turned on,
Since the capacitor C1 is charged toward the power supply voltage VCC to increase the terminal voltage, the output voltage of the operational amplifier 37 of the soft start circuit 28 also gradually increases.
For this reason, the bias voltage VC1 applied to the reference wave generation circuit 21 also gradually increases.
The peak value of the reference wave output from 1 also gradually increases, and the effective value of the output voltage of the inverter 18 gradually increases.

The operational amplifier 37 of the soft start circuit 28
When the output voltage further rises and exceeds a certain value, the diode D1 enters a reverse bias state and turns off. In this state, the output voltage of the error amplifying circuit 26 is directly supplied to the reference wave generating circuit 21 as the bias voltage VC1, and the soft start of the inverter 18 is completed, and the steady operation is performed.

In the steady operation, as described above, the bias voltage VC1 is feedback-controlled based on the error between the output voltage of the inverter 18 and the reference voltage Vrf. Specifically, for example, when the effective output voltage of the inverter 18 falls below a target value, this is
, And the bias voltage VC1 is raised.
The effective value of the output voltage of inverter 18 is raised to a target value.

On the other hand, the output of the inverter 18 is passed as a pulse signal to the CPU 2 through a phase comparator 25B.
4 The CPU 24 outputs a synchronizing pulse to the multiplexer 32 of the reference wave generation circuit 21 so that a phase difference does not occur between the output of the inverter and the output of the commercial power supply, which is also captured as a pulse signal through the phase comparator 25A. As a result, the reference wave synchronized with the commercial power supply is output from the reference wave generation circuit 21, and the output voltage of the inverter 18 has the same phase as the commercial power supply voltage.

Incidentally, the power supply device 10 of the present embodiment is
Normally, the inverter 18 is operated to supply power to the CATV relay amplifier, which is a load, while charging the storage battery 17 with the power from the rectifier 16. Here, in the present embodiment, since the AC voltage waveform output from the inverter 18 is controlled to be a trapezoidal wave as described above, the reactive current is suppressed even if the load is capacitive. Power factor can be improved.

When an abnormality occurs in the inverter 18, an inverter abnormality detection circuit 40 provided in the control circuit 19 detects the abnormality from a change in the output voltage of the inverter 18, drives the output changeover switch 13, and relays the inverter 18. Disconnect from the amplifier and connect the bypass circuit 11 to the relay amplifier. At this time, since the inverter 18 is synchronized with the commercial power supply, the switching operation is performed without inrush current flowing.

As described above, in the power supply device 10 of the present embodiment, the inverter 18 and the bypass circuit 11
Among them, the inverter 18 is connected to an external load (a relay amplifier for CATV), and the inverter 18 is connected to the control circuit 19.
As a result, a so-called soft start is performed so that the effective value of the output voltage gradually increases, so that a large inrush current can be prevented from flowing. Moreover, since the AC voltage output from the inverter 18 is a trapezoidal wave, the reactive current can be suppressed even when a capacitive load such as a CATV relay amplifier is connected, and the AC voltage is supplied as a sine wave. Power factor can be improved as compared to

<Other Embodiments> The present invention is not limited to the above embodiments. For example, the following embodiments are also included in the technical scope of the present invention.
In addition to the following, various changes can be made without departing from the scope of the invention.

(1) Reference Wave Generation Circuit 21 of the Above Embodiment
In the above, the trapezoidal wave was generated by the switching operation of the multiplexer 32. For example, first, a sine wave was generated, and the peak portion was cut by a limiter circuit using a zener diode, so that the peak portion became flat. A trapezoidal wave may be generated.

(2) The PWM signal generation circuit 22 of the above-described embodiment generates a drive signal to be supplied to the inverter 18 by analog processing. For example, the PWM signal generation circuit 22 receives digital data from a ROM, digitally processes the digital data, and performs drive processing. A configuration for generating a signal may be adopted.

(3) The multiplexer 32 of the above embodiment
May be different from each other in resistance value. In this case, a trapezoidal waveform may be generated by making the switching timing of the multiplexer 32 different.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an uninterruptible power supply according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit provided in the uninterruptible power supply.

FIG. 3 is a circuit diagram of a reference voltage generation circuit.

FIG. 4 is a circuit diagram of a soft start circuit and an error amplifier circuit.

FIG. 5 is a graph showing a reference wave.

FIG. 6 is a block diagram showing a configuration of a conventional uninterruptible power supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Uninterruptible power supply 11 ... Bypass circuit 13 ... Output changeover switch 16 ... Rectifier 17 ... Storage battery 18 ... Inverter 19 ... Control circuit (Inverter control means) 21 ... Reference wave generation circuit (Trapezoidal wave generation means) 28 ... Soft start circuit 24 ... CPU

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Nagahama 1 Kishijoin Nishinosho Inobaba-cho, Minami-ku, Kyoto GS E Co., Ltd. F term (reference) 5G015 FA02 GA04 GA07 HA04 HA15 JA05 JA23 JA24 JA33 JA34 5H007 AA02 AA17 BB05 CC03 CC09 DA06 DB01 DB12 EA02 EA15 GA02 GA03

Claims (4)

[Claims] 1. An uninterruptible power supply device comprising an inverter for receiving an electric power from a rectifier and / or a storage battery connected to an external AC power supply and outputting an AC voltage, wherein power is supplied from the inverter when power supply to an external load is started. An inverter control means for gradually increasing the effective value of the output voltage to perform soft start. 2. The uninterruptible power supply according to claim 1, wherein said inverter control means sets the output voltage waveform of said inverter to a trapezoidal waveform. 3. An uninterruptible power supply device comprising an inverter for receiving an electric power from a rectifier and / or a storage battery connected to an external AC power supply and outputting an AC voltage, wherein the AC voltage waveform output from the inverter is trapezoidal. An uninterruptible power supply device comprising a wave generating means. 4. A bypass circuit for directly or transforming and outputting an AC voltage received from the external AC power supply, and a power supply from the inverter is cut off when an abnormality occurs in the operation of the inverter. The uninterruptible power supply according to any one of claims 1 to 3, further comprising switching means for switching an output so as to supply power.