JPH05260685A - Uninterruptible power supply equipment - Google Patents

Abstract

PURPOSE:To make the efficient use of an inverter by making an inverter equipped in an uninterruptible power supply equipment perform the suppression of the higher harmonic current of load at normality of an AC power source and the charge and voltage suppression of the DC part of an inverter, and the voltage constant control of a load input terminal, and work as an uninterruptible power supply equipment the time of service interruption. CONSTITUTION:A first switch 2, in series with an AC power source 1, a second switch 3, in parallel with the output end of the first switch 2, and an inverter 7, in series with load 5, are provided, respectively. An inverter detects a power current IS, power voltage VS, and load input end voltage VL, respectively, and generates higher harmonic voltage proportionate to the higher harmonic component of the power supply current, its fundamental wave component, effective component voltage by the in-phase and the orthogonal component, and the fundamental wave voltage of reactive component voltage, and performs the control at the time of normal AC voltage.

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 for supplying AC power to load equipment such as a computer without interruption, and particularly to AC to load equipment while charging an inverter when AC power is supplied. The present invention relates to an improvement in an uninterruptible power supply device that keeps the voltage constant and operates as a device that suppresses a load facility harmonic current to the AC power supply side.

[0002]

2. Description of the Related Art Conventionally, as this type of uninterruptible power supply, a system shown in FIG. 7 (see Japanese Patent Publication No. 49-41733) is known. In the figure, 1 is an AC power supply, 2 is a first switch, 9 is a reactance circuit, 8 is a rechargeable storage battery, 7
Is an inverter, 5 is load equipment, and 6 is a ripple removal filter.

When the AC power supply 1 is normal, the first switch 2 is ON, and AC power is sent to the load equipment 5 via the reactance circuit 9. On the other hand, the inverter 7 receives the DC power of the storage battery 8 and outputs the AC voltage having the same frequency as the AC power supply 1 and having substantially the same voltage through the ripple removing filter 6. At this time, by providing a phase difference between the output voltage of the inverter 7 and the voltage of the AC power supply 1, electric power flows from the AC power supply 1 into the inverter 7, and the inverter 7 operates as a charger to charge the storage battery 8. To do. Also, load equipment 5
Since the inverter becomes a fundamental wave with respect to the harmonic current generated by, the reactance circuit 9 has a lower impedance with respect to the harmonic current, and the harmonic current becomes
To the AC power supply 1 side and not to the AC power supply 1 side. When the AC power supply 1 fails, the first switch 2 is turned off, and the inverter 7 sends out AC power to the load equipment 5.

[0004]

In this conventional example, the reactor used in the reactance circuit 9 needs to be designed so as to operate at a commercial frequency, and there is a drawback that both the size and the weight increase. Further, in order to operate the inverter 7 as a charger, the fundamental wave voltage of the AC power source 1 is E1, the output fundamental wave voltage of the inverter 7 is E2, the reactance of the reactance circuit is x, the AC power source 1 and the inverter 8
When the voltage phase difference of is expressed as θ, it is necessary to control the electric power W flowing into the inverter 7 from the AC power source 1 represented by the formula (1) through the reactance circuit 9, but it is clear from the formula (1). As described above, the value of sin ^{-1 has} to be obtained, which makes the control complicated.

[Equation 1] W = E1 ・ (E2 / x) ・ sin θ (1)

Further, in order to suppress the inflow of the harmonic current of the load equipment 5 into the AC power source 1 side, the difference between the impedance on the AC power source side and the impedance on the inverter 7 side is used. However, since the ripple removing filter 6 is connected, the effect of suppressing harmonics is not sufficient.

Further, when the power supply voltage V _s fluctuates, there is no function of correcting it.

[0007]

An uninterruptible power supply device according to the present invention is an uninterruptible power supply device that is provided in series between an AC power supply and a load, the first uninterruptible power supply being connected in series to an AC power supply.
Switch, a ripple removal filter connected in parallel to the output side of the first switch, an inverter connected in series with the first switch, and a DC side of the inverter. A storage battery; and a control device for controlling the inverter, the control device detecting a power supply current and an AC power supply voltage, and detecting a fundamental wave component and a harmonic component thereof,
Means for multiplying the power source current harmonic component by a gain K to output a harmonic voltage command; and a difference between the DC voltage command of the storage battery and the DC voltage of the storage battery and the power supply current fundamental wave component for inputting the power supply. A means for outputting an effective component voltage command having the same phase or a reverse phase as the current fundamental wave component, and the normal-time gate by inputting the harmonic component voltage command and the effective component voltage command and comparing their vector composite value and the triangular wave. Means for outputting a pulse, means for inputting a load voltage command, and outputting a gate pulse during a power failure so that the inverter output becomes an AC voltage,
The gate pulse at power failure, the gate pulse at normal time, and the AC power supply voltage are input, and when the AC power supply is normal, the first switch is turned on and the second switch is turned off, and the gate pulse at normal time is supplied to the inverter. When the AC power source fails, the first switch is turned off and the second switch is turned on to output the gate pulse during the power failure to the inverter.

The uninterruptible power supply device according to the present invention further inputs the difference between the load voltage command and the load voltage, the power supply current fundamental wave component, and the AC power supply voltage, and the power supply current fundamental wave component and 90 °.
Or, comprising means for outputting a reactive voltage command having a phase difference of −90 °, and means for outputting the gate pulse at the normal time,
The reactive component voltage command, the effective component voltage command, and the harmonic component voltage command may be input, and a gate pulse may be output during normal operation by comparing a vector composite value of them and a triangular wave.

[0009]

The uninterruptible power supply of the present invention detects the AC power supply voltage, and when the AC power supply is normal, suppresses the harmonic current of the load from flowing out to the power supply, and controls the DC voltage of the inverter. The load voltage is controlled to be constant.

This principle will be described with reference to the fundamental wave vector diagram of FIG. 3, the operation waveform diagram of FIG. 4, and the single line connection diagram including the uninterruptible power supply device of FIG.

First, harmonic suppression will be described. In the figure, V _S is the AC power supply voltage, V _C is the voltage of the uninterruptible power supply, and V _L is the load voltage, which are connected in series with the system impedance and the load current I _S flows. The uninterruptible power supply device connected between the AC power supply and the load may be controlled so that the load current has a sine wave. That is, the uninterruptible power supply unit supplies the power supply current harmonic component I _SH (subscript H represents the harmonic component).

[Equation 2] By controlling so that I _SH = 0 (2),

[Equation 3] V _C = V _SH −V _LH (3) and the uninterruptible power supply generates harmonic voltage as shown in FIG. The component I _SH can be zero.

Next, the DC voltage V _D control and the load voltage V _L control of the inverter will be described. In FIG. 3, the rise or fall of the DC voltage V _D can be controlled by generating the fundamental wave voltage V _A in phase with or opposite to the source current fundamental wave component I _S. Further, the power source current fundamental wave component I _S
Fundamental wave voltage V of lead component or lag component with different 90 ° phase
By generating _B , the rise or fall of the load voltage V _L can be controlled.

Therefore, the fundamental wave voltage generated by the uninterruptible power supply becomes V _C ′ which is the vector addition of V _A and V _B.

As described above, when the AC power supply is normal, the uninterruptible power supply generates a voltage in which the harmonic voltage V _C and the fundamental wave voltage V _C ′ are added in vector. Control and load voltage control can be performed.

During a power failure of the AC power supply, the inverter is disconnected from the AC power supply and the inverter is controlled to generate a constant load voltage V _L.

[0016]

FIG. 1 is a diagram showing the main circuit configuration of an uninterruptible power supply unit according to the present invention, and FIG. 2 is a diagram showing an embodiment of a control unit. In these figures, 3 is a second switch, 21 is a power supply current analysis circuit, 22 is a first addition circuit, 23 is a reactive component voltage command circuit, 24 is a second addition circuit, 25 is an effective component voltage command circuit, 26 Is a harmonic component voltage command circuit, 27 is a comparison circuit, 28 is a sine wave PWM pulse generation circuit, 29 is a selection circuit, and the same reference numerals as those in FIG. 7 denote the same parts.

The storage battery 8 is an inverter 7 when the AC voltage is normal.
This is for stabilizing the DC side voltage of, and is a power supply source to the load 5 of the inverter 7 at the time of AC power failure.
The ripple removing filter 6 is for removing the switching component of the inverter 7.

In FIG. 2, when the AC power supply 1 is conducting, the power supply current analysis circuit 21 inputs the power supply voltage V _S and the power supply current I _S, and changes from the power supply current I _S to the power supply voltage V _S of the fundamental wave current. The component I _SF and the harmonic current component I _SH are output to the reactive component voltage command circuit 23, the active component voltage command circuit 25, and the harmonic component command circuit 26, respectively.

The first adder circuit 22 inputs the load voltage command V _L ^* and the load voltage V _L, and the difference between them is the AC voltage deviation ΔV.
_It is output as _L to the reactive voltage command circuit 23.

The reactive voltage command circuit 23 uses the AC power supply voltage V _S.
Then, the fundamental wave current component I _SF and the AC voltage deviation component ΔV _L are input. For example, as shown in FIG. 3, the fundamental wave current component I _SF is delayed in phase from the AC power supply voltage V _S , and the AC voltage deviation component is Δ
When V _L is positive, that is, when the load voltage V _L is lower than the command, the fundamental wave current component I _SF proportional to the AC voltage deviation ΔV _L
The reactive circuit voltage command V _B advanced 90 ° in phase is compared with the comparison circuit 27.
Output to.

The harmonic component voltage command circuit 26 receives the harmonic current component I _SH , multiplies the gain K by K, and outputs the harmonic component voltage command V _SH .

The second adding circuit 24 inputs the DC voltage command V _D ^* of the storage battery 8 and the DC voltage V _D , and outputs the difference to the effective voltage command circuit 25 as a DC voltage deviation ΔV _D.

The effective component voltage command circuit 25 inputs the power source voltage V _S and the DC voltage deviation ΔV _D, and when the DC voltage deviation ΔV _D is positive as shown in FIG. 3, that is, the DC voltage V
_{When D} is lower than the command, the effective voltage command V _A in phase with the power supply voltage V _S is output to the comparison circuit 27.

The comparator circuit 27 inputs the harmonic voltage command V _SH , the reactive voltage command V _B , and the active voltage command V _A , compares them with the added value, and performs a triangular wave comparison.
To the selection circuit 29. The harmonic voltage command V _SH causes the inverter 7 to operate at time T _{0 as} shown by V _C and I _S in FIG.
After that, the harmonic voltage V _C is generated to suppress the harmonic current.

The inverter 7 is controlled by V _{C in} FIG. 3 so that the reactive voltage command V _B controls the load voltage V _L constantly and the active voltage command V _A controls the DC voltage V _D of the storage battery. The fundamental wave voltage as shown in ′ is generated.

The sine wave PWM pulse generation circuit 28 generates a power failure gate pulse GV that generates an AC voltage of the same phase as the AC power supply 1 to the load 5 when the AC power supply 1 fails, and outputs it to the selection circuit 29.

The selection circuit 29 inputs the gate pulse GI in normal time, the sine wave PWM pulse and the power supply voltage V _S , and turns on the first switch 2 and turns off the second switch 3 when the AC power supply 1 is normal. Such a switch command S is output to the first switch and the second switch 3, and the normal-time gate pulse GI is output to the inverter 7 as the gate signal G.

Next, at the time of power failure, the selection circuit 29 operates as the first switch 2
Switch command S for turning off the switch and turning on the second switch 3
Is output to the first switch 2 and the second switch 3, and the gate pulse GV during a power failure is output to the inverter 7 as a gate signal.

FIG. 6 shows an embodiment in which a three-phase inverter is used in a three-phase system, which is connected to the system by a transformer 4.

[0030]

As is apparent from the above description of the operation, according to the present invention, when the AC power source fails, the first switch is turned off and the second switch is turned on, and the AC power is supplied to the load. When the AC power supply is normal, the first switch is turned on, the second switch is turned off, and the power supply current, the power supply voltage, the load voltage and the DC voltage of the inverter are detected, and the storage battery DC voltage is detected. The inverter is operated so as to suppress the inflow of the harmonic current of the load to the power supply side while performing the constant control of the load voltage and the constant control of the load voltage, so that the reactance circuit conventionally installed on the AC power supply side is removed. It is possible to configure a small and inexpensive uninterruptible power supply having a simple control circuit capable of performing constant control of load voltage.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an embodiment of a control device for an uninterruptible power supply according to the present invention.

FIG. 3 is a fundamental wave vector diagram for illustrating the principle of the uninterruptible power supply device of the present invention.

FIG. 4 is an operation waveform diagram of the uninterruptible power supply device of the present invention.

FIG. 5 is a single line connection diagram including the uninterruptible power supply device of the present invention.

FIG. 6 is a main circuit configuration diagram showing an embodiment when a three-phase inverter is used in a three-phase system.

FIG. 7 shows a main circuit connection diagram of a conventionally known uninterruptible power supply device of this type.

[Explanation of symbols]

 1 AC power supply 2 1st switch 3 2nd switch 4 Transformer 5 Load equipment 6 Ripple removal filter 7 Inverter 8 Rechargeable storage battery 9 Reactance circuit 21 Power supply current analysis circuit 22 First addition circuit 23 Reactive voltage command circuit 24 Second addition circuit 25 Effective voltage command circuit 26 Harmonic voltage command circuit 27 Comparison circuit 28 Sine wave PWM pulse generation circuit 29 Selection circuit

Claims (2)

[Claims] 1. An uninterruptible power supply device provided in series between an AC power supply and a load, the first switch being connected in series to the AC power supply, and the output side of the first switch. A ripple removal filter connected in parallel, an inverter connected in series with the first switch, a storage battery connected to the DC side of the inverter, and a control device for controlling the inverter, The control device detects a power supply current and an AC power supply voltage and detects a fundamental wave component and a harmonic component thereof, and a means for multiplying the power supply current harmonic component by a gain K to output a harmonic voltage command, A means for inputting the difference between the direct current voltage command of the storage battery and the direct current voltage of the storage battery and the power supply current fundamental wave component and outputting an effective component voltage command in phase with or opposite to the power supply current fundamental wave component, and the harmonic Wave voltage command and effective voltage finger Means for outputting a gate pulse in a normal state by comparing the vector composite value of these with a triangular wave, and a means for inputting a load voltage command and outputting a gate pulse during a power failure so that the inverter output becomes an AC voltage. And the gate pulse at the time of power failure, the gate pulse at the time of normal operation, and the AC power supply voltage as input, and when the AC power supply is normal, the first
Turning on the switch, turning off the second switch, outputting the normal gate pulse to the inverter, turning off the first switch and turning on the second switch when the AC power supply is interrupted, An uninterruptible power supply device that outputs a gate pulse to the inverter during a power failure. 2. A reactive component having a phase difference of 90 ° or −90 ° with respect to the power supply current fundamental wave component by inputting the difference between the load voltage command and the load voltage, the power supply current fundamental wave component and the AC power supply voltage. Means for outputting a voltage command, means for inputting the reactive component voltage command, the effective component voltage command, and the harmonic component voltage command, and outputting a gate pulse in a normal state by comparing their vector composite value and a triangular wave The uninterruptible power supply according to claim 1, further comprising: