JPH04108389U - Uninterruptible power system - Google Patents

Abstract

(57) [Summary] [Purpose] The object of the present invention is to obtain a standby type uninterruptible power supply in which the waveform of the AC voltage supplied from the AC power supply to the load is not distorted. [Structure] In a device that supplies AC power to a load by switching between a bypass line to which an AC power source is connected and a non-bypass line to which a battery is connected, the AC power from the AC power source is converted to DC. , a self-excited rectifier that constantly charges the battery, and an inverter that converts DC power from the battery to AC power when the AC power supply is out of power and supplies the converted AC power to the load;
a detection means for detecting the current flowing through the load; a comparison means for comparing the current detected by the detection means with a reference sine wave current to obtain a difference current; Equipped with a gate drive means that performs pulse width modulation control of a self-excited rectifier so that the AC power is injected through the excited rectifier.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention constantly supplies power from a commercial power supply to the load using a bypass line as a power supply path. The present invention relates to a standby (SPS) type uninterruptible power supply that supplies power.

0002

[Conventional technology]

This type of standby type uninterruptible power supply uses a rectifier (converter) and an inverter. Unlike uninterruptible power supplies that supply power to loads through Since the harmonic current contained in the load current is supplied to the direct load, it is directly passed to the AC power supply. leak. Most of the loads are switching power supplies such as computers, and the waveform is It contains a large amount of harmonic current, and therefore the AC power supply voltage is also distorted.

0003 Figure 4 shows a configuration diagram of a conventional stand-by type uninterruptible power supply. When the power supply 7 is normal, the AC power from the AC power supply 7 is connected via the bypass line 1. is supplied to a computer (CPU) load 6.

0004 On the other hand, when the AC power supply 7 is normal, the AC power from the AC power supply 7 is directly transmitted through the rectifier 2. This converted DC power is used to power the battery 3 at constant current or constant current. It is constantly charged to the maximum pressure.

[0005] When the AC power supply 7 is out of power, the DC power from the battery 3 is interrupted. The converter 4 converts the AC power into AC power, and the converted AC power is supplied to the load 7. be done.

[0006] Note that the gate of the rectifier 2 is controlled by a gate signal from the gate drive device 9. It will be done. That is, the current flowing through the battery 3 is detected by the instrument current transformer 10, and this The detected current and the current input to the inverter 4 are input to the comparator 8 to generate a deviation signal. By inputting this deviation signal to the gate drive device 9, this gate drive is performed. A gate signal is obtained from the dynamic device 9.

[0007]

[Problem that the idea aims to solve]

The computer load 6 consists of a switching power supply, and the current waveform has a large amount of harmonics. It becomes something that includes. Therefore, this harmonic current passes through bypass line 1. The voltage flows out to the AC power supply 7, and this voltage waveform is distorted. This invention is a standby battery that does not distort the AC voltage waveform supplied from the AC power supply to the load. The purpose of this invention is to provide a type of uninterruptible power supply.

[0008]

[Means to solve the problem]

In order to achieve the above objectives, this invention aims to The switching means switches the negative to one of the non-bypass lines to which the battery is connected. In devices that supply AC power to loads, the AC power from the AC power source is converted to DC. and a self-excited rectifier that constantly charges the battery, and a self-excited rectifier that constantly charges the battery, and a converts the DC power from the battery into AC, and converts the converted AC power into an inverter that supplies the load; and a detection means that detects a current flowing through the load. , compare the current detected by this detection means with the reference sine wave current, and calculate the difference current. A comparison means and a difference current obtained by this comparison means are passed through the self-excited rectifier in opposite phases. The self-excited rectifier is controlled by pulse width modulation so as to inject the AC power into the AC power source. It is equipped with gate driving means.

[0009]

[Effect]

According to the present invention, the difference current between the current flowing through the load and the reference sine wave current, that is, the harmonic The self-excited rectifier is pulse-width-modulated controlled so that the waves are detected and are out of phase. Therefore, harmonics are removed and the AC voltage waveform supplied to the load is not distorted.

0010

【Example】

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

[0011] FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, which is configured as follows. It is. Bypass line 1 to which AC power supply 7 is connected and battery 3 are connected. AC is applied to the load by switching to either of the non-bypass lines 20 using the changeover switch 5. It supplies electricity.

0012 In such a device, AC power from the AC power supply 7 is converted to DC, and the battery It is equipped with a self-excited rectifier 22 that constantly charges the battery 3. It consists of a self-extinguishing element such as a turn-off thyristor. AC power supply 7 During a power outage, the DC power from the battery 3 is converted to AC, and this converted AC is It includes an inverter 4 that supplies power to a computer load 6. Also, load 6 A current transformer 25 detects the current flowing in the A comparator 23 is provided for comparing the sinusoidal currents and determining the difference current. Furthermore, this The difference current obtained by the comparator 23 is sent to the AC power source 7 through the self-excited rectifier 22 in opposite phase. gate driving means 2 that performs pulse width modulation control of the self-excited rectifier 22 so as to inject It is equipped with 4.

[0013] Note that the current value flowing through battery 3 should not become excessive, and the inverter In order to control the input voltage of current transformer 21 to be constant, the detected current of current transformer 21 and The voltage signal of the inverter 4 is input to the comparator 23.

[0014] In such a configuration, the current flowing to the load 6 is detected by the current transformer 25. The comparator 23 detects the difference current between this detected value and the reference sine wave current. This ratio The difference current detected by the comparator 23 is a harmonic. So that these harmonics are in opposite phase Since the self-cooled rectifier 22 is controlled by pulse width modulation by the gate drive device 24, , harmonic components are removed, and the AC voltage waveform supplied to the load 6 is not distorted.

[0015] Specifically, as shown by the solid line in FIG. Detect the difference current between the load current I1 shown by the broken line and the reference sine wave current I2 shown by the broken line. The self-excited rectifier 22 is PWM-controlled to inject into the AC power source 7 in opposite phase. In addition, The self-excited rectifier 22 is also controlled to charge the battery 3. Because of this, the AC input waveform of the computer load 6 is a sine wave as shown in Figure 3. It becomes I3.

[0016]

[Effect of the idea]

According to the present invention, the AC voltage waveform supplied from the AC power source to the load is not distorted. We can provide an integrated uninterruptible power supply.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an uninterruptible power supply device of the present invention.

FIG. 2 is a diagram for explaining a method of controlling the self-excited rectifier of FIG. 1;

FIG. 3 is a diagram showing the load current waveform in FIG. 1;

FIG. 4 is a diagram showing an example of a conventional uninterruptible power supply.

[Explanation of symbols]

1... Bypass line, 3... Battery, 4... Inverter, 5... Selector switch, 6... Computer load, 7... AC power supply, 20... Non-bypass line, 21... Current transformer, 22
...Self-excited rectifier, 23...Comparator, 24...Gate drive device, 25...Current transformer.

Claims (1)

[Scope of utility model registration request] 1. In a device that supplies AC power to a load by switching between a bypass line to which an AC power source is connected and a non-bypass line to which a battery is connected by a switching means, the AC power from the AC power source is switched to a non-bypass line to which a battery is connected. a self-excited rectifier that constantly charges the battery; and an inverter that converts DC power from the battery into AC power when the AC power supply is out of power and supplies the converted AC power to the load; a detection means for detecting the current flowing through the load; a comparison means for comparing the current detected by the detection means with a reference sine wave current to obtain a difference current; An uninterruptible power supply device comprising: gate driving means that performs pulse width modulation control on the self-excited rectifier so as to inject into the AC power source via the self-excited rectifier.