JPS62254632A - Non-interruption source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an uninterruptible power supply that supplies uninterruptible power to computers and communication devices.

[Conventional technology]

FIG. 6 is a circuit diagram of a conventional uninterruptible power supply device shown in, for example, Japanese Patent Publication No. 49-41734. In the figure, 1 is a commercial power source, an AC power source such as a diesel generator, and 2 is a switch. A) When the AC power supply 1 is normal, it is on, and when there is a power outage, it is off.

3 is a switch that operates in the opposite direction to switch 2; That is, when the AC power supply 1 is normal, it is off, and when there is a power outage, it is turned on. 4 is a rechargeable storage battery, and 5 is an inverter, which has a built-in filter for converting the output waveform into a sine wave with less distortion.

6 is a load, and 7 is a reactance circuit mainly composed of a reactor, a capacitor, or a reactor and a capacitor.

Next, the operation will be explained. When the AC power source 1 is normal, the switch 2 is on, and the AC power source 1 is directly sent to the load 6.

On the other hand, the switch 3 is off, and the inverter 5 is connected to the AC power supply 1 via the reactance circuit 7. At this time, the voltage of AC power supply 1 is J −= q2 El
cos (ωt+θ) (1) The fundamental wave component of the output voltage of the inverter 5, e2 = ! 2
B2 cos G)j −−−−−=−−−−(
2), and the reactance circuit 7 has an inductive reactance ω
If expressed as L, the current i and power P flowing from the AC power source 1 through the reactance circuit 7 to the inverter 5 are: i-even(el-e2) dt EIB2.

= −11t31 jl θ ・・・・・・
(41ωL) From equation (4), the power P flowing from the AC power supply 1 to the inverter 5 is a function of the phase difference θ between the output voltages of the AC power supply 1 and the inverter 5. I understand that there is something.

Therefore, when the AC power source 1 is normal, the storage battery 4 can be charged at a constant voltage and a constant current by controlling the phase difference θ.

In equation (4), the control resolution of charging power P is 0.0I
Assuming that PU is required and that the phase difference between the inverter and AC power supply can be controlled with an accuracy of Q,ldeg, HIE
z.

ωL = SIn θ
...Song... (51=0.
175 (pu), and an inductive reactance of 0.175 pu is required. Here, in order to reduce the ripple component of the current flowing into the inverter 5, lf = Ji32 = lp
Let u be the size of the reactance that is practically required.

When the AC power supply 1 is out of power, the switch 2 is turned off, the switch 3 is turned on, and the load 6 is supplied with AC power from the inverter 5.

As mentioned above, in the conventional uninterruptible power supply shown in Fig. 6,
A reactor 7 and a switch 3 are provided, and a reactance circuit 7 is inserted between the inverter 5 and the AC power source 1 to increase the impedance only when the AC power source 1 is in a normal charging operation.

The reason is that, as can be seen from equation (4) above, the smaller the impedance L, the larger the rate of change ΔP/Δθ of the power P with respect to control with a phase difference of 0, which allows for very fine control of the phase difference θ. This is because it is required to do so.

Next, although it is not directly related to charging operation, #1 where L is small
, 1" The rate of change ΔQ/Δ(El-B2) of the reactive power Q flowing due to the lightning difference between the inverter 7L and the AC lightning source 1 also increases, making stable parallel operation difficult. If there is a method that does not require minute control of ΔQ and Δ(El-B2), it is possible to create a system that eliminates the reactance circuit 7 and switch 3 by using only the internal impedance of the inverter 5 itself. Can be configured.

[Problem to be solved by the invention] Since the conventional uninterruptible power supply is configured as described above, it requires a current actance of about 0.175 pu when charging the storage battery, so it is difficult to charge the storage battery during a power outage. When supplying alternating current power to a load through the inverter 5 using the inverter 5 as a power source, switches 2 and 3 are required to short-circuit the reactance circuit 7.

Furthermore, in order to suppress the magnitude of reactance to approximately 0.1751)U, K is required to control the phase difference with an accuracy of 1 degree.

However, in reality, the phase of the AC power source constantly fluctuates by several degrees, so there is a problem in that it is not easy to control the phase difference with an accuracy of 0.1 cleg.

This invention was made to solve the above-mentioned problems, and it is possible to reduce the reactance required when charging a storage battery by using a reactance circuit in common with a filter for improving the output waveform of an inverter. The objective is to obtain an economical and highly reliable uninterruptible power supply that does not use a switch for short-circuiting.

[Failure to solve the problem]

When the AC power supply is normal, the uninterruptible power supply device according to the present invention obtains a sine wave command value of the inverter AC output current to charge the storage battery voltage to the set voltage, and instantly tracks the inverter output current to the sine wave command value. By controlling the inverter DC current to a predetermined value, the storage battery is charged, and in the event of an AC power outage, the inverter output voltage is controlled to follow the instantaneous value to a sine wave with little distortion.

[For production]

In the uninterruptible power supply of this invention, when the AC power supply is normal, the AC current flowing into the inverter is controlled and the storage battery voltage is charged to the set voltage, and when the AC power supply is out of order, the output voltage of the inverter is a sine wave with little distortion. The AC power is controlled to follow the instantaneous value, and stable AC power is supplied to the load.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is an AC power supply, 2 is a switch, 4 is a storage battery, and 5
a is the AC filter reactor 5 from the inverter main body.
b and capacitor 5C, and is the main circuit of an inverter that converts direct current to alternating current of arbitrary voltage and frequency, such as an inverter using a high frequency PWM modulation method using a full bridge configuration of high frequency switching elements. be. 6 is the load. 101 is a voltage detector, 10
2 is a power failure detection circuit, 103 is a switch, 104 is a synchronous circuit that generates a signal synchronized with the AC power supply, and 105 is 'IT'.
106 is a voltage detector, 107 is a current detector, 108 is a charging control circuit, and 110 is a constant voltage control circuit, and these two circuits 108 and 110 constitute an inverter output current control circuit. 109 is a voltage detection circuit, 111 is a switch, 112 is a PWM circuit,
113 is a drive circuit.

FIG. 2 shows a charging control circuit 10 used in the embodiment shown in FIG.
8, 201 is a voltage controlled amplifier, 202 is a limiter, 203 is a multiplier, 204 is a divider, 205 is a multiplier, and 206 is a current controlled amplifier.

Figure 3 shows constant voltage control circuit 1 used in the *m example in Figure 1.
10, 301 is an effective value detection circuit, 302
is a voltage controlled amplifier, 303 is a multiplier, and 304 is a voltage controlled amplifier.

FIG. 4 is a circuit diagram of the switch 2 used in the embodiment of FIG. 1, which includes a transistor 20, a diode 21 . 22
．． It has 23.24.

The operation of this invention will be explained. In FIG. 1, if the AC power supply 1 is normal, the switch 2 is on, the switch 103 is on, and the switch 111 is on the charging control circuit 10.
This will be the B side. AC power source 1 is directly sent to load 6 via switch 2 . The inverter 5a is controlled by the output of the charging control circuit 10B via a PWM circuit 112 and a drive circuit 113, and charges the storage battery 4.

When the AC power supply 1 has a power outage, the power outage detection circuit 102 is activated, the switch 2 is turned off, the switch 103 is turned off, and the switch 111 is placed on the constant voltage control circuit 110 side. Suin 103
When turned off, the (rsilω) generation circuit 105 operates at its own frequency.
13 to supply AC power to the load 6.

When the AC power supply 1 is restored, the power failure detection circuit 10 detects the power restoration.
2 is detected and the switch 103 is turned on. Synchronous circuit 1
04 synchronizes the V25ina> generation circuit 105 with the AC power supply, and after confirming this, turns on the switch 2, and turns on the switch 11.
1 to the charging control circuit 10B side, the AC power supply 1 operates normally.

The operation of charging control circuit 108 will be explained.

The charging control circuit 108 is configured as shown in FIG. 2, and the storage battery voltage is charged to a set voltage by an integral type control system.

Difference Δ between storage battery setting voltage VB ref and storage battery voltage VB
V is the charging current command IB by the voltage control amplifier 201.
It becomes ref. By passing this charging current command IBref through the limiter 202, constant current charging is performed when the deviation ΔV is large, and transition to constant voltage charging is performed when the deviation ΔV is small.

The charging current command I B ref can be converted into a current command value on the alternating current side of the shifter 5a by the following operation.

From the charging current command IBref and the storage battery voltage VB, the charging power command PB is: PB=IBrefxvB If the voltage effective value of the AC power source 1 is VSrms, the charging current effective value command lArm5 on the AC side of the inverter 5a is: I A rms = PB /VS rms Therefore, on the AC side of the inverter 5a, the effective value of the power factor l I A rm
If a current of s flows, IBre will be generated on the DC side of the inverter
A current of f will flow.

Charging current effective value command I A rms・ds inω
Multiply by t to convert into instantaneous charging current command IAref,
The current control amplifier 206 causes the AC side current IA of the inverter 5a to instantaneously follow the instantaneous charging current command IArefK.The AC side current IA follows the command while having a ripple component of the PWM frequency. The ripple current at the PWM frequency varies depending on the size of the handle 5b. Even if the ripple current exceeds the allowable value of the storage battery 4 by making the reactor 5b small, a capacitor 7 that absorbs the ripple current may be installed in parallel with the storage battery 4.

If the magnitude of the ripple current, the voltage of the storage battery 4, and the voltage of the AC power source 1 are kept constant, the reactor 5b may be smaller if the PWM frequency becomes higher.

Figure 5 shows the AC side current IA and the instantaneous charging current command IAref.
A diagram is shown. Figures 2 and 3 are enlarged views of Figure 1, and 2
is f PWM = '/T s reactor = L・, 3
is f PWM = 5/T s reactor = L15.

Referring to FIG. 3, the operation of the constant voltage control circuit 110 will be explained. The difference ωV between the output setting voltage V ref and the load voltage effective value V rms of the voltage of the load 6 is input to the voltage control amplifier 302, and the obtained VL rms K K s in ωt
An instantaneous voltage command VL ref is created from K by multiplying by . By making the voltage control amplifier 304 respond quickly, the load voltage V
L to follow the command VLref.

Since the measure loop is an integral type, the effective value of the load voltage V
rms corresponds to the set voltage V ref. Furthermore, since it has a high-speed voltage minor loop using the voltage control amplifier 304, a sine wave voltage with little distortion can be supplied even if the load 6 is nonlinear.

In addition, although the case of a single-phase inverter was explained in the above embodiment, this concept of controlling a PWM modulation inverter can be applied to a three-phase inverter by using a control circuit for each power generation.

Furthermore, in the above embodiment, the case where the current minor Φ loop of charging control and the voltage minor Φ loop of constant voltage control are performed by instantaneous value control using proportional control was explained.
Effects similar to those of the above embodiment can be obtained even with control using I control, PID control, finite time settling control using a digital controller, etc. In addition, in FIG. 2, the multiplier 203. Although the divider 204 is used, the storage battery voltage V'B and the voltage effective value of the AC power source vs.
While the rms is changing, it is often about ±l (l), which is relatively small, so it is not necessary to perform calculations strictly according to theory.

For example, it is possible to perform the charging function of the storage battery by simply performing constant calculations, such as by omitting X@Y=X@(YO+ΔY)'EEYOX.

〔Effect of the invention〕

As described above, according to the present invention, since the AC side current of the inverter is directly instantaneously controlled when charging the storage battery voltage to the set voltage, the inverter operates as a constant current source, so the reactor is It is small in size 2, the charging reactor and the waveform improving filter reactor can be shared, and the switch 3 shown in FIG. 6 can be omitted. Also,
In the event of an AC power outage, the constant voltage control system for the inverter output voltage has an instantaneous voltage control function, so even nonlinear loads can be supplied with a sine wave voltage with little distortion.

Therefore, the device can be manufactured at low cost and has improved reliability.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an uninterruptible power supply according to an embodiment of the present invention, Fig. 2 is a block diagram of a charging control circuit, Fig. 3 is a block diagram of a constant voltage control circuit, and Fig. 4 is a switch circuit. 5 is an explanatory diagram of charging control, and FIG. 6 is a block diagram showing a conventional uninterruptible power supply. 1 is an AC power supply, 4 is a storage battery, 5a is an inverter, 105
108 is a charging control circuit, and 110 is a constant voltage control circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Patent applicant: Mitsubishi Electric Corporation (2 others) Figure 1 1, 2 Figure 5 (3) 0 ". Maro 1.10.16 Showa 1920 Month Day

Claims (1)

[Claims] In the event of a power outage of the AC power supply, the DC power of the storage battery is converted to AC power by an inverter to supply AC power to the load, and when the AC power supply is supplied, the power of the AC power supply is converted to DC power by the rectification function of the inverter. In the uninterruptible power supply device configured to charge the storage battery with a predetermined voltage or current, the inverter is of a high frequency PWM modulation type and the voltage or current is charged based on a feedback signal of the terminal voltage or current of the storage battery. a control circuit that generates a DC current command value to be passed through the storage battery; a sine wave generation circuit that generates a sine wave synchronized with the AC power source; and a signal that changes the amplitude of the sine wave according to the DC current command value. an inverter output current control circuit that instantaneously controls the output current of the inverter using the AC output current command value of the inverter.