CN205787755U

CN205787755U - A kind of alternative current power failure detection circuit of PLC

Info

Publication number: CN205787755U
Application number: CN201620525569.4U
Authority: CN
Inventors: 周开荣
Original assignee: Hangzhou Fine Stone Intelligent Technology Co Ltd
Current assignee: Zhejiang Liangshi Intelligent Technology Co Ltd
Priority date: 2016-06-01
Filing date: 2016-06-01
Publication date: 2016-12-07
Anticipated expiration: 2026-06-01

Abstract

The utility model discloses the alternative current power failure detection circuit of a kind of PLC, including exchange input optocoupler and positive inversion signal conversion supercircuit, described exchange input optocoupler includes exchange input and exchanges optocoupler, described positive inversion signal conversion supercircuit include phase inverter and with door, described exchange input, exchange optocoupler, phase inverter and be sequentially connected with door.The alternative current power failure detection circuit using a kind of PLC of the present utility model has the advantages that 1) power down response real-time height；2) low and high level detection；3) light-coupled isolation, the weak problem of capacity of resisting disturbance improves Surge handling capability, is effectively improved the unfailing performance of system；4) circuit is simple, and cost performance is high.

Description

A kind of alternative current power failure detection circuit of PLC

Technical field

This utility model relates to the power down pile defection in the control system of PLC converter field, is specifically related to the alternative current power failure detection circuit of a kind of PLC.

Background technology

The single three-phase electricity detection technique of existing exchange and circuit have many types of, but the structural principle of circuit is broadly divided into following several:

1) voltage comparator+optocoupler mode

Unidirectional current after AC rectification is used voltage comparator that high voltage direct current is done voltage ratio relatively by this circuit, when voltage is less than a certain voltage threshold, produces actuating signal, by optocoupler, signal is passed to CPU and detects.This circuit anti-interference ability is poor, comparator hysteresis is more weak, and response speed is slow, and Surge handling capability is poor.

2) isolating transformer+amplifier mode

This circuit uses isolating transformer to realize the function of isolation, but the volume of isolating transformer is relatively big, causes the biggest taking can to PCB space volume.Compare aforesaid way, improve detection reliability and response speed, but sacrifice volume, the low ratio of sexual valence.

3) light-coupled isolation mode

This circuit uses Phototube Coupling to realize the detection to alternating current, the signal of circuit output has square-wave signal, when CPU removes to detect this kind of signal, the biggest to CPU data expense, and inspection policies error detection easily occurs and reduces the real-time of system time unreasonable, be not suitable for using in the highly reliable system with high real-time.

Existing detection mode all can realize the function of alternating current power failure pile defection, but is not highly desirable in using in the system of high real-time and high reliability.Such as the highest to reliability and real-time in PLC control system.AC detection of power loss is not in time, significant data can be caused cannot to store before system power failure or the logical modes such as storage capacitors that strengthen are to extend the method for electric energy to improve this valuable PCB space not only taken up of reliability and electric capacity equipment at any time uses capacitance the most slowly to decline for a long time, cause the safety factor step-down that data preserve.After causing normal boot-strap, some parameter is lost and is caused the system cannot the normally puzzlement such as work.If the frequent misoperation of power-off signal, PLC can be caused frequently memorizer being write data, cause the memory chip write life-span drastically to shorten, initiating failure.So the system requirements detection of power loss responses such as PLC converter are in time, the requirement of real time and reliability to improve system little to cpu resource expense.

Utility model content

For solving above technical problem, this utility model offer a kind of power down response real-time is high, capacity of resisting disturbance is strong, circuit simple PLC alternative current power failure detection circuit.

The alternative current power failure detection circuit of a kind of PLC of the present utility model, including exchange input optocoupler and positive inversion signal conversion supercircuit, described exchange input optocoupler includes exchange input and exchanges optocoupler, described positive inversion signal conversion supercircuit include phase inverter and with door, described exchange input, exchange optocoupler, phase inverter and be sequentially connected with door.

Further, there is TO_CPU network described connection with the door other end.

This utility model by photoelectric coupled circuit realize isolation, coupling electric capacity and audion constitute phase inverter, by constitute with door phase signals antithesis superpose form positive inversion signal convert supercircuit.Ultimate principle: the square wave outfan in optocoupler detection increases a phase inverter, makes original square-wave signal be transformed to anti-phase and as another the most anti-phase output of road output.Then, by being overlapped with the method signal that this signal phase of goalkeeper is a positive and a negative.As combined oscillogram and table 1-and door truth table, can draw, after AC power down, positive and anti-phase two signals all export high level and then export high level with door, if AC has electricity, opposite in phase between positive and inversion signal, then with door output low level (having 0 output 0 with door input).So, if AC power down, optocoupler just cannot export square-wave signal and maintain high level always, phase inverter input no signal is then output as height simultaneously, and TO_CPU network then maintains high level power loss event i.e. to produce CPU can be effectively improved the real-time of system power failure detection to low and high level detection or interruption detection.

Table 1 and door truth table

Positive inversion signal conversion supercircuit Main Function is: after AC powers on during optocoupler output intent signal, allows positive and negative two signal (according to table 1, input can have 0 0) under the effect with door be output as low level.AC power down optocoupler cannot export square wave and maintain high level and inversion signal also to export high level, and under the effect with door, TO_CPU network is forced to export high level (according to table 1, input complete 1 and go out 1).

The alternative current power failure detection circuit of a kind of PLC of the present utility model, has the advantages that

1) power down response real-time is high.Because circuit uses positive inversion signal conversion supercircuit to solve the problem in zero passage dead band, as long as AC power down will persistently maintain low level condition by destructive test signal, so AC power down is substantially Tong Bu with the electric low level of detection signal there is not dead band.That is produce AC to fall and to trigger power loss event time delay the least, existing detection scheme can be efficiently solved and exist and detect dead band and the problem of response time length；

2) low and high level detection.Solve that to use light-coupled isolation mode to detect signal be the square wave problem that cpu resource expense greatly affects system real time when causing CPU detection difficult or detection；

3) light-coupled isolation, the weak problem of capacity of resisting disturbance improves Surge handling capability, is effectively improved the unfailing performance of system；

4) circuit is simple, and cost performance is high.

Accompanying drawing explanation

Fig. 1 is testing circuit figure of the present utility model；

Fig. 2 is testing circuit oscillogram of the present utility model；

Fig. 3 is application simplified schematic diagram in this utility model；

Fig. 4 is application INT signal detection figure in this utility model.

Detailed description of the invention

It is explained this utility model below, it should be understood that example is that scope of the present utility model is determined according to claims with core content for this utility model being described rather than to restriction of the present utility model with instantiation.

As shown in Figure 1, the alternative current power failure detection circuit of a kind of PLC that the present embodiment provides, including exchange input optocoupler and positive inversion signal conversion supercircuit, exchange input optocoupler includes exchange input 1 and exchanges optocoupler 2, positive inversion signal conversion supercircuit include phase inverter 3 and with door 4, exchange input 1, exchange optocoupler 2, phase inverter 3 and be sequentially connected with door 4；It is connected with the door other end and has TO_CPU network.

The alternative current power failure detection circuit of a kind of PLC of the present embodiment, has the advantages that 1) power down response real-time height.Because circuit uses positive inversion signal conversion supercircuit to solve the problem in zero passage dead band, as long as AC power down will persistently maintain low level condition by destructive test signal, so AC power down is substantially Tong Bu with the electric low level of detection signal there is not dead band.That is producing AC to fall and to trigger power loss event time delay the least, as in figure 2 it is shown, AC power down can occur exchanging positive half cycle, at zero crossing, exchange negative half period, three regions all produce raw AC power loss event.Existence due to positive inversion signal conversion supercircuit, make response without dead band (dead band power down occurs at dead band CPU if existing scheme exists detection, and cannot make an immediate response power loss event), so power down response time delay is minimum, existing detection scheme can be efficiently solved and there is detection dead band and the problem of response time length；

4) circuit is simple, and cost performance is high.

The present embodiment application power failure data in PLC preserves: by the PLC system of Alternating Current Power Supply, by artificial maintaining or grid power blackout etc., cause PLC people for or unexpected power down, before power down, PLC should keep the technical parameter of user, system may be caused cannot normally to work after again powering on if customer parameter cannot preserve, needing again could be normal to PLC input associated technical parameters, brings the most not convenient to production.Therefore the present embodiment is powered cut-out or accident power-off by detection AC220V, and CPU preserves the function of the current user data of PLC to ferroelectric memory, again goes up electric energy and works on realizing PLC.PLC system requires that AC power down triggers signal stabilization, and response is the most reliable, the feature that capacity of resisting disturbance is strong；Forbidding to disturb or miss power-off signal causes CPU frequently to repeat data erasable to memorizer and make memory device write life-span premature failure and scrap.AC220V cut-out event CPU of powering can respond rapidly to store related data, forbids to occur that data have not stored the electric energy that power supply provides the most depleted.Cause user data loss.System simplified schematic diagram is shown in Fig. 3, and the design at the power module of PLC increases the power-fail detection circuit of the present invention, detects the situation of Alternating Current Power Supply.When outside artificial shutoff switch or grid power blackout or total lock tripping operation cause system power failure.When power-fail detection circuit detects exchange short of electricity, then produce the power-fail interrupt signal (such as Fig. 4) of CPU.CPU is immediately terminated current task, goes the task of performing to preserve user's technical parameter data of PLC program.Wait after preservation that power-supply system removes end power down.When again powering on, CPU recalls user's technical parameter data of PLC program the most immediately, and system can be run automatically by the technical parameter of subscriber equipment.Owing to system have employed exchange input optocoupler+positive inversion signal conversion supercircuit and the mode of CPU interrupt response, PLC user's technical parameter preserves response rapidly, and capacity of resisting disturbance is strong, and reliability is high.

Embodiment described above is preferably scheme of the present utility model, and this utility model is not made any pro forma restriction, also has other variant and remodeling on the premise of without departing from the technical scheme described in claim.

Claims

1. the alternative current power failure detection circuit of a PLC, it is characterised in that: include exchange input optocoupler and just Inversion signal conversion supercircuit, described exchange input optocoupler includes exchange input and exchanges optocoupler, described Positive inversion signal conversion supercircuit include phase inverter and with door, described exchange input, exchange optocoupler, anti- Phase device and being sequentially connected with door.

The alternative current power failure detection circuit of a kind of PLC the most according to claim 1, it is characterised in that: There is TO_CPU network described connection with the door other end.