CN1421978A - Three-phase uninterrupted power supply system - Google Patents

Abstract

The invention provides a three-phase uninterrupted power supply system which is used for receiving an input three-phase alternating-current voltage to provide an output alternating-current voltage. The uninterrupted power supply system comprises a rectifying circuit, a first voltage converter, a second voltage converter and a first voltage converter, wherein the rectifying circuit is used for receiving an input three-phase alternating current voltage and outputting a direct current voltage; a converter circuit for converting the DC voltage into an output AC voltage; a capacitor pair connected with the rectifying circuit and the converter circuit through a first bus and a second bus; and a neutral circuit connected to the pair of capacitors for connecting the DC voltage and the output AC voltage at the same potential for grounding.

Description

Three-phase uninterruptible power supply system

technical field

The invention relates to a three-phase uninterrupted power supply system.

Background technique

As shown in Figure 1, a general traditional three-phase uninterruptible power supply system includes a filter 10, a pre-stage rectifier circuit 11, a post-stage commutation circuit 12, a capacitor pair (13, 14), and a transformer 15 and a ground wire 16.

It is generally known that the traditional three-phase uninterruptible power supply system uses the filter 10 to process an input three-phase voltage, which has a relatively limited conversion efficiency and a large impact on the input three-phase voltage due to the low power factor and large current harmonics. Harmonic pollution of mains power supply system. This is also the place that is in urgent need of improvement in the uninterruptible power supply system.

Furthermore, as is well known to those skilled in the art, the transformers used in traditional uninterruptible power supply systems are not only bulky and heavy, but also extremely expensive. On the other hand, most of the transformers used today are designed with low-frequency transformers, which will greatly reduce the efficiency of voltage conversion in uninterruptible power supply systems.

In addition, the number of batteries used in the uninterruptible power supply system needs to match the input rectified voltage. Such a design often results in the need for a large number of batteries to supply the rectifier circuit or store electricity.

To sum up, the existing uninterruptible power supply system has the above-mentioned technical shortcomings that need to be solved urgently.

Contents of the invention

The main purpose of the present invention is to provide an uninterruptible power supply system for reducing the current harmonics of the input voltage source.

Another object of the present invention is to provide an uninterruptible power supply system for improving the power factor of the input voltage.

Another object of the present invention is to provide an uninterruptible power supply system for increasing the output conversion power.

The above object of the present invention is achieved in this way: an uninterruptible power supply system is used to receive an input AC voltage to provide an output AC voltage, which includes a rectifier circuit for converting the input AC voltage into a DC voltage; a commutation circuit for converting the DC voltage into the output AC voltage; a capacitor pair connected to the rectification circuit and the commutation circuit via a first bus and a second bus; and a middle A neutral circuit is connected to the pair of capacitors for connecting the DC voltage and the output AC voltage at the same potential for grounding.

Preferably, the uninterruptible power supply system further includes a pre-stage circuit connected to the rectifier circuit to provide the input AC voltage, and the pre-stage circuit is a three-phase four-wire AC circuit.

Ideally, the pre-stage circuit also includes a switch component, which is used to control the turn-on and turn-off of the input AC voltage.

Ideally, the uninterruptible power supply system further includes an auxiliary circuit, which is connected to the pre-stage circuit through the switch component. The auxiliary circuit includes a charger and a storage battery. When the AC voltage is input, the charger stores electric power in the storage battery; and when the input AC voltage is interrupted, the electric energy stored in the storage battery is provided to converted into the DC voltage to be further converted into the output AC voltage.

Preferably, the uninterruptible power supply system further includes a subsequent circuit connected to the converter circuit to provide the output AC voltage.

More ideally, the subsequent stage circuit is a three-phase AC circuit, and the rectification circuit is a full-bridge rectification circuit.

Ideally, both the rectification circuit and the commutation circuit include six switches, each of which includes a power component and a diode for controlling the turn-on and turn-off of the input AC voltage.

Ideally, the power component is composed of an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET) or an intelligent power module (IPM).

Ideally, the uninterruptible power supply system further includes a booster circuit electrically connected between the neutral circuit and the storage battery, which stores power in the storage battery for use when the input AC voltage is interrupted. , can provide the electric power stored in the storage battery to be converted into the DC voltage, and further be converted into the output AC voltage.

Below, the technical features and advantages of the present invention will be described in further detail in combination with the embodiments and accompanying drawings.

Description of drawings

Fig. 1 is a schematic circuit diagram of a known uninterruptible power supply system;

Fig. 2 is the circuit diagram of the first preferred embodiment of the uninterruptible power supply system of the present invention;

Fig. 3 is the circuit diagram of the second preferred embodiment of the uninterruptible power supply system of the present invention;

Fig. 4 is the circuit diagram of the third preferred embodiment of the uninterruptible power supply system of the present invention;

FIG. 5 is a circuit schematic diagram of the fourth preferred embodiment of the uninterruptible power supply system of the present invention.

Detailed ways

As shown in FIG. 2 , the first preferred embodiment of the uninterruptible power supply system of the present invention includes a rectifier circuit 21 , a converter circuit 22 , a capacitor pair ( VDC1 , VDC2 ) and a neutral circuit 20 . The uninterruptible power supply system of the present invention further includes a pre-stage circuit 23, electrically connected to the front end of the rectifier circuit 21, which is a three-phase four-wire AC circuit, used to provide an input three-phase AC voltage, and at the same time, in the pre-stage circuit 23 may additionally be provided with a switch 30 for controlling the on and off of the input AC voltage, as shown in FIG. 3 .

When the input three-phase voltage is input to the full-bridge rectifier circuit 21 from the pre-stage circuit 23 , the switch components I11 to I16 included in the rectifier circuit 21 convert the input three-phase AC voltage into a DC voltage. After passing through the capacitor pair ( VDC1 , VDC2 ), the converted DC voltage is converted by the commutation circuit 22 to convert the DC voltage into an output AC voltage, which is then output through the subsequent three-phase circuit 24 . In FIG. 2, the uninterruptible power supply system of the present invention also includes a first bus BUN ⁺ , which is coupled with the rectifier circuit 21 and an end point of the capacitor pair (VDC1, VDC2), and a second bus ^BUN- , which is coupled to the other terminal of the commutation circuit 22 and the capacitor pair (VDC1, VDC2). After forming a ground potential between the first bus BUN ⁺ and the second bus ^BUN- , the neutral circuit 20 is connected between the capacitor pair (VDC1, VDC2) and connected in series with the subsequent three-phase circuit 24, so that The DC voltage and the output AC voltage are connected at the same potential for grounding.

In addition, as shown in FIG. 2 , the rectification circuit 21 of the present invention includes six switch components I11 to 116 , and the commutation circuit 22 also includes six switch components I1a to I6a. Each switching component replaces a traditionally used switch with a high power conversion component, and it includes a power component 211 and a diode 212 made of an insulated gate bipolar transistor (insulated gate bipolar transistor, IGBT). To control the turn-on and turn-off of the input AC voltage. Certainly, besides the IGBT design, the high power conversion components used in the present invention can also be replaced by power metal oxide semiconductor field effect transistors (Power MOSFETs) or intelligent power modules (IPMs). The IGBT developed by this design combining the dual advantages of MOSFET and bipolar transistor has high-speed switching and is easy to meet the needs of high withstand voltage and large capacity, which can make the uninterruptible power supply system of the present invention light and compact. The advantages of high efficiency and low noise.

As shown in Figure 3, the second preferred embodiment of the uninterruptible power supply system of the present invention can also be integrated with an auxiliary circuit 31 connected to the front stage circuit 23, and utilize the charger 32 arranged in the auxiliary circuit 31 With storage battery 33, to release and store electric power effectively. When the mains supply is normal, the input three-phase AC voltage is charged to the storage battery 33 via the charger 32 . When the mains power is abnormal, that is, when the input three-phase AC voltage is interrupted, the auxiliary circuit 31 is charged as a discharge circuit, and the storage battery 33 is stored in the storage battery by conducting with the switching switch 30 on the previous stage circuit 23. The electrical power is released for conversion into a DC voltage, which is further converted into the output AC voltage.

On the other hand, in FIG. 3, the uninterruptible power supply system of the present invention can be further connected with a bypass loop (bypass loop) 33 for maintenance purposes.

4 and 5 respectively show the third preferred embodiment and the fourth preferred embodiment of the uninterruptible power supply system of the present invention. As shown in FIG. 4 and FIG. 5, the uninterruptible power supply system of the present invention may include a boost circuit 40 or 50, which is connected between the first bus BUN ⁺ and the second bus ^BUN- , and is also connected to the middle bus The neutral line 20 is connected at the same potential to realize the purpose of reducing the number of batteries used in the uninterruptible power supply system of the present invention. The boosting circuits 40 and 50 in FIGS. 4 and 5 each include a charger 41 , batteries 42 and 52 , and a high-efficiency switching element 43 . In FIG. 4 , the battery 42 is connected in series, and the neutral line 20 is connected to the charger 41 first, and then forms an equipotential connection with the battery 42 . In FIG. 5 , the storage battery 42 is set separately, and the neutral wire 20 is only connected between the high-efficiency switch assembly 53 and the capacitor pair (VDC1, VDC2).

To sum up the above, the uninterruptible power supply system of the present invention has the effects of reducing input harmonics, increasing input power factor, and reducing the number of batteries, so it can indeed achieve the purpose of the present invention.

But the above description is only a preferred embodiment of the present invention, certainly not to limit the scope of the present invention implementation, that is, all simple equivalent changes and modifications carried out according to the claims of the present invention and the content of the description should still be It belongs to the scope covered by the patent of the present invention.

Claims (13)

1, a kind of uninterrupted power supply system in order to accept an input ac voltage so that an output AC voltage to be provided, is characterized in that comprising:

One rectification circuit is exported a direct current voltage in order to receive this input ac voltage;

One converter circuit is exported this output AC voltage in order to receive this direct voltage;

One electric capacity is right, and it is connected with this rectification circuit and this converter circuit with one second bus via one first bus; And

One neutral circuit is connected to this capacitance group, in order to this direct voltage of idiostatic connection and this output AC voltage, with the usefulness as ground connection.

2, uninterrupted power supply system as claimed in claim 1 is characterized in that also comprising a front stage circuits, and it is connected in this rectification circuit so that this input ac voltage to be provided.

3, uninterrupted power supply system as claimed in claim 2 is characterized in that this front stage circuits is a three-phase and four-line alternating current circuit.

4, uninterrupted power supply system as claimed in claim 2 is characterized in that this front stage circuits also comprises a switch module, in order to conducting and the shutoff of controlling this input ac voltage.

5, uninterrupted power supply system as claimed in claim 4 is characterized in that also comprising an auxiliary circuit, and it is connected to this front stage circuits.

6, uninterrupted power supply system as claimed in claim 5 is characterized in that this auxiliary circuit comprises a charger and a storage battery, and is connected to this front stage circuits by this switch module.

7, uninterrupted power supply system as claimed in claim 1 is characterized in that also comprising a late-class circuit, and it is connected in this converter circuit so that this output AC voltage to be provided.

8, uninterrupted power supply system as claimed in claim 7 is characterized in that this late-class circuit is a three-phase circuit.

9, uninterrupted power supply system as claimed in claim 1 is characterized in that this rectification circuit comprises six switches, and each switch comprises a (PCC) power and a diode respectively, in order to conducting and the shutoff of controlling this input ac voltage.

10, uninterrupted power supply system as claimed in claim 9 is characterized in that this (PCC) power is an insulation lock bipolar transistor, wherein a kind of composition the among a mos field effect transistor and the intelligent power conversion module.

11, uninterrupted power supply system as claimed in claim 1 is characterized in that this converter circuit comprises six switches, and each switch comprises a (PCC) power and a diode respectively, in order to conducting and the shutoff of controlling this input ac voltage.

12, uninterrupted power supply system as claimed in claim 11 is characterized in that this (PCC) power is an insulation lock bipolar transistor, wherein a kind of composition the among a mos field effect transistor and the intelligent power module.

13, uninterrupted power supply system as claimed in claim 6, it is characterized in that also comprising a booster circuit, be electrically connected between this neutral circuit and this storage battery, in order to store electric power in this storage battery, and when this input ac voltage interrupts, provide the electric power that stores in this storage battery, in order to convert this direct voltage to, further to be converted into this output AC voltage.

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