RU183734U1 - SUPERCONDENSER UNINTERRUPTIBLE POWER SUPPLY OF DC BUS FREQUENCY CONTROLLED DRIVE - Google Patents

Abstract

The utility model belongs to the class of uninterruptible power supplies and can be used in the design of new and modernization of in-service variable frequency drives. The uninterruptible power supply (UPS) of the DC bus (ШПТ) contains a supercapacitor storage device (SCN) connected to the on / off unit using a bi-directional converter, which serves to match the voltage on the ШПТ and SKN. The proposed solution improves the stability of the parameters of the voltage of ШПТ in the conditions of instability of the supply network and sudden changes in the load parameters.

Description

The utility model belongs to the class of uninterruptible power supplies and can be used in the design of new and modernization of in-service variable frequency drives (VFDs) in single-phase or three-phase 230V / 400V networks with unstable parameters (deep subsidence or power surges, short-term voltage interruptions), as well as with an unstable and very variable load.

The most common problem during the operation of variable frequency drives is the voltage dips (low quality of power supply) and, as a result, the VFD shutdown caused by the voltage drop on the DC bus (ШПТ) of the VFD. To deal with such outages, the so-called uninterruptible power supplies (UPS) with double conversion are used (see, for example, patent RU 34820 U1). The principle of operation of such a UPS is based on the conversion of alternating voltage to direct with further storage of stored energy in batteries and the reverse process of converting direct current to alternating current, after which the alternating current is already converted into direct current in the rectifier link (input cascade) of the VFD.

The problem solved by the creation of the declared uninterruptible power supply is to further increase the reliability of the VFD with low quality of power supply, while the technical result achieved by solving this problem is to increase the stability of the voltage parameters of the ACB in the conditions of instability of the supply network and sudden changes in the load parameters.

To achieve the result, it is proposed an uninterruptible power supply (UPS) DC bus (SHPT), comprising an on / off unit configured to communicate with a DC bus, a control unit (comparator) with output and inputs, and a supercapacitor drive (SKN) connected with the on / off unit using a bi-directional converter, which serves to coordinate the voltage on the splitters and the SKN, while the output of the control unit is connected to the on / off unit, and the inputs are connected, respectively but with a DC bus and supercapacitor storage.

A double layer supercapacitor (EDLC) was used as a supercapacitor.

The ability to achieve the result is determined by the ability of supercapacitors, in particular, double layer supercapacitors, the ability to instantly take or give energy, thereby ensuring continuous maintenance of a stable voltage on a split wire, which allows almost instantly reacting to changes in the parameters of a split pin when changing load parameters and supply network parameters.

The essence of the utility model is illustrated by the circuit diagram of the connection of the claimed UPS to the DC bus of a variable frequency drive (VFD) (Fig. 1), on which the following positions are indicated:

1 –– input stage (rectifier) of VFD of transformation of alternating voltage into constant (AC / DC);

2 - DC bus VFD;

3 - inverter VFD (DC / AC);

4 - electric motor;

5 - supercapacitor drive (SKN);

6 - control unit (comparator); compares the voltage on the SHPT and SKN;

7 - unit for turning on and off the drive SKN when the voltage parameters of the splitters go beyond the nominal;

8 - bidirectional converter (DC / DC).

The principle of operation of the declared UPS involves the following sequence of actions. The input stage 1 of the VFD converts the alternating voltage to direct voltage and supplies it to the ШПТ 2. The control unit (comparator) 6 compares the voltage to the ШПТ and to SKN.

When discharged SKN 5 - direction A in figure 1, the control unit 6 controls the power unit 7 and through a bi-directional converter 8 provides charge supercapacitor drive to the voltage required for the DC bus in nominal mode. Additionally, the converter 8 serves to match the voltage on the DC bus and supercapacitor storage.

 When there are dips in the network or the appearance of a rapidly changing load, the supercapacitor drive 5 is discharged through the converter 8 to the DC bus 2 - direction B in Fig. 1. At the same time, the control unit 6 constantly compares the voltage on the DC bus and the supercapacitor drive and provides a charge / discharge mode of the drive to ensure the rated voltage on the split-ball screw drive.

Thus, a supercapacitor drive (SCN) performs the function of short-term load maintenance in case of network failures or complete power failure (statistics show that 80% of cases of power failure are short-term in nature, no more than 5 seconds), which in many cases is much more efficient than using batteries traditionally used in UPSs with double conversion due to significantly longer service life of supercapacitors, a wider temperature range of operation utation and the possibility of working outdoors, compactness and low weight, maintenance-free, environmentally friendly.

  The proposed solution ensures stable operation of the VFD under conditions of instability of the supply network and VFD in 230V / 400V networks with high efficiency due to the inherent property of supercapacitors being instantly charged / discharged, provides short-term load support in the event of a power failure, provides compensation for the pulse component of the load, asymmetry in the network power and load capacities of VFDs, compactness, maintenance-free, environmental friendliness, long service life, the ability to scale for work You are with several VFDs on a common DC bus, maintaining critical processes as normal.

Claims (2)

1. An uninterruptible power supply (UPS) for a DC bus (ШПТ), comprising an on / off unit configured to communicate with a DC bus, a control unit (comparator) with output and inputs, and a supercapacitor storage device (SKN) connected to the switching unit on / off using a bi-directional converter, which serves to match the voltage on the splitters and SKN, while the output of the control unit is connected to the on / off unit, and the inputs are connected respectively to the DC bus and supercapacitor. 2. The source of claim 1, wherein a double layer supercapacitor (EDLC) is used as the supercapacitor.

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