CN203707871U

CN203707871U - Low-voltage ride-through apparatus of frequency converter

Info

Publication number: CN203707871U
Application number: CN201420022700.6U
Authority: CN
Inventors: 赵占强; 刘少华
Original assignee: SHAANXI PULIAN ELECTRIC Co Ltd
Current assignee: SHAANXI PULIAN ELECTRIC Co Ltd
Priority date: 2014-01-15
Filing date: 2014-01-15
Publication date: 2014-07-09
Anticipated expiration: 2024-01-15

Abstract

The utility model relates to a low-voltage ride-through apparatus of a frequency converter. The low-voltage ride-through apparatus is composed of a rectifier unit, a chopper boost unit, a differential pressure control unit, a direct-current safety source input unit and an uninterruptible alternating-current control power output unit. When a system detects that the system voltage is lower than a set value, a duty ratio of an IGBT is calculated according to a boost chopper formula and the chopper boost unit is controlled to carry out boosting; and meanwhile, a direct-current output value is detected and PID closed-loop control is carried out, thereby realizing accurate outputting and ensuring the stable output of the frequency converter. When the system voltage is reduced to be below 40% and even the short-time power lossing occurs, the current is inputted by the direct-current safety source input unit at the direct current side and then is outputted by the chopper boost unit. Meanwhile, the system also provides an uninterruptible alternating-current control power output unit, thereby ensuring the uninterruptible operation of the control power source of the frequency converter control cabinet and guaranteeing that the frequency converter operates stably under the circumstances of the low voltage mode of the system and even existence of the short-time power-lossing phenomenon.

Description

Frequency converter low voltage ride through device

Technical field

The utility model design is a kind of device that guarantees the uninterrupted operation of frequency converter in critical process, is applicable to the frequency converter of critical process in producing, and frequency converter can normally be worked in the time of system low-voltage, has guaranteed the continuity of producing.

Background technology

In recent years, along with the requirement of country to energy-saving and emission-reduction, and the development of power electronic technology, frequency converter is accurate with its speed governing, easy to use, and the advantage that defencive function waits comprehensively progressively replaces traditional debugging apparatus, is applied on a large scale in all trades and professions.

In the use of frequency converter, when falling in short-term appears in line voltage, even the short time when dead electricity, can be triggered the protection of frequency converter, and causes frequency converter to shut down, and dragging motor is shut down simultaneously.If load is general load, after inspection, restart again frequency converter.And if critical loads is shut down and can be caused chain reaction, trigger more senior protection, thereby affect the continuous production of full factory, cause very large economic loss.

Solution is to solve by the method for the DC side increase direct-flow storage battery at frequency converter at present.This scheme needs batteries and charging device, and investment is large, and batteries is very high to environmental requirement, needs regular charge and discharge maintenance, and cost is also very high.

Summary of the invention

In order to eliminate above-mentioned disadvantage, the utility model provides a kind of frequency converter low voltage ride through device, while falling for resolution system voltage, for frequency converter provides reliable and stable DC power supply, guarantee the normal stable operation of frequency converter, maintain the normal work of dragging system, guarantee the stability of production, avoid unnecessary economic loss.

The scheme that the utility model adopts is as follows.

A kind of frequency converter low voltage ride through device in parallel between AC power and frequency converter, the outlet side of frequency converter low voltage ride through device is connected on direct current wiring place of frequency converter, in the time of system low-voltage, by copped wave after lower AC rectification is boosted and outputed to frequency converter.Its specific features is as follows.

System is inputted by two-way power supply, is respectively the direct current 220V power supply that interchange 380V power supply and direct current cabinet provide; One road direct current outputs to frequency converter, and a road alternating current 220V is exported to control Power supply.Wherein direct current 220V input unit and alternating current 220V output unit are apolegamy, can select according to field condition.

Wherein exchanging 380V power supply and received and do not controlled rectification unit by circuit breaker Q F1, is direct current by AC rectification; Passing through the BOOST boost chopper being formed by reactor L1, IGBT1 and fast recovery diode FDR; The effect of capacitor C is energy storage filtering; Form pressure reduction control output circuit by D1, D2 and QF2, automatically control input and the excision of frequency converter low voltage ride through device; The direct current 220V input circuit being made up of QF3, FU1, FU2, D3 and D4, by the DC side of direct current 220V access frequency converter low voltage ride through device, guarantees to exchange in system the direct current guarantee of the situation of short supply interruption; The alternating current 220V being made up of QF4, TM1 and UPS is uninterruptedly controlled power supply output loop, from TM1 transformer, interchange 380V is become to alternating current 220V and connects UPS output and do and control power supply and use.

Accompanying drawing explanation

Fig. 1 is frequency converter low voltage ride through device system diagram.

Fig. 2 is frequency converter low voltage ride through device schematic diagram.

Fig. 3 is loop control theory.

Fig. 4 is control logic block diagram.

Embodiment

Below in conjunction with accompanying drawing and concrete enforcement, the utility model is further elaborated.

Shown in Fig. 1 is frequency converter low voltage ride through device system connected mode, is connected in parallel between three-phase alternating-current supply and frequency converter DC side.In the time that system voltage falls or disappear in short-term for frequency converter provides reliable and stable DC support.

Figure 2 shows that the inside schematic diagram of frequency converter low voltage ride through device.

In the time that system voltage is stablized, frequency converter directly provides ac power power supply by power distribution cabinet, and frequency converter low voltage ride through device is in hot standby state.Be that QF1 and QF2 close a floodgate, but BOOST copped wave loop do not work, due to the pressure reduction control of D1 and D2, on major loop, electric current does not flow through.

In the time that frequency converter low voltage ride through device detects that system voltage drops into below 90%, system calculates the needed duty ratio of IGBT in BOOST boost chopper loop according to the direct current output valve of setting and the system voltage value of falling, control IGBT and carry out copped wave control, improve by uncontrollable commutating circuit whole go out DC voltage value, detect this magnitude of voltage and set point simultaneously and compare and carry out PID control.

The computing formula of duty ratio is released by BOOST step-up formula.BOOST step-up formula is:

（1）

Wherein: U ₀for the BOOST output voltage that boosts

U _sfor the BOOST output voltage that boosts

D is IGBT duty ratio

And three-phase bridge is not controlled the computing formula of rectification and is:

（2）

Wherein: U _dfor rectification output dc voltage value

U is three-phase alternating current phase voltage value

U _lfor three-phase alternating current line magnitude of voltage

U in formula 1 ₀with the U in formula 2 _dso can be drawn by formula 1 and formula 2 for same value in present case:

（3）

Wherein k is proportionality coefficient (between 0.8 ~ 1.2).

When system voltage drops to below 40% or when short-time loss of power supply, system will provide DC power supply by DC220V direct current emergency power supply, then through BOOST boost chopper, DC220V is raised to setting voltage.

If when frequency conversion tank control power supply is alternating current 220V, frequency converter low voltage ride through device can provide uninterrupted power supply, guarantee the uninterrupted operation of frequency conversion tank control.Circuit breaker Q F4, transformer TM1 and uninterrupted power supply UPS realize this function.Wherein the effect of transformer TM1 is to be alternating current 220V by interchange 380V power conversion.

Figure 3 shows that PID loop control theory figure, compare by set-point and the instantaneous value detecting, carry out PI and adjust in controller PLC program, output pulse signal is to IGBT drive circuit board, drive IGBT, control the BOOST boost chopper output DC voltage value approaching with set-point.

Fig. 4 is PLC control logic block diagram.System initialization first carries out Real-Time Monitoring to system voltage, and judge whether that voltage falls, foundation is to fall more than 90% to be left intact, continue to detect, if dropped into below 90%, but do not drop into below 40%, through type 3 calculates duty ratio output and controls the BOOST boost chopper work that IGBT forms, carry out PID closed-loop control, accurately output simultaneously; If while dropping into below 40%, direct current emergency power supply replaces not to be controlled rectification and powers to DC loop, exports corresponding duty ratio and controls BOOST circuit, carries out PID simultaneously and controls output.If it is normal that system voltage recovers, IBGT quits work, and blocks direct current output, enters hot standby state.

Claims

1. a frequency converter low voltage ride through device, described frequency converter low voltage ride through device is parallel between system three-phase alternating current 380V power supply and frequency converter DC side, described frequency converter low voltage ride through device comprises rectification unit, copped wave boosting unit, pressure reduction control unit, direct current emergency power supply input unit and uninterruptedly controls power supply output unit, and its feature is as follows:

1) described rectification unit is not controlled rectifier bridge by three phase full bridge and is formed, and system three-phase alternating current 380V power supply is by the ac input end of circuit breaker Q F1 access rectification unit, and DC output end connects copped wave boosting unit;

2) the BOOST booster circuit that described copped wave boosting unit is made up of IGBT, reactor L and fast recovery diode FDR, reactor L store electrical energy when IGBT conducting, when IGBT turn-offs, reactor L discharges electric energy and is added on direct voltage, thereby direct voltage is raise, and the duty ratio of controlling IGBT just can be controlled the height of output voltage;

3) described pressure reduction control unit is made up of diode and circuit breaker Q F2, when the anode electromotive force of diode is during higher than cathodic electricity kinetic potential, and diode current flow, on the contrary to turn-off, the effect that is wherein parallel to the capacitor C before diode is filtering;

4) described direct current emergency power supply input unit is made up of circuit breaker Q F3 and fuse, diode, in the time that system voltage is low to moderate below 40% even short-time loss of power supply, direct current 220V emergency power supply is input to the input of copped wave boosting unit by circuit breaker Q F3, fuse and diode;

5) described uninterrupted control power supply output unit is made up of circuit breaker Q F4, transformer TM1 and UPS, and transformer becomes 220 alternating voltages to power 380V AC voltage conversion to UPS, and UPS exports to frequency converter control cabinet uninterrupted control power supply is provided.