CN101441956B

CN101441956B - Control circuit for electromagnet of low-tension switch electric appliance

Info

Publication number: CN101441956B
Application number: CN2008102020447A
Authority: CN
Inventors: 朱文灏; 邵福山; 曾萍; 胡景泰
Original assignee: Shanghai Dianke Electrical Technology Co Ltd
Current assignee: Shanghai Dianke Electrical Technology Co Ltd
Priority date: 2008-10-31
Filing date: 2008-10-31
Publication date: 2011-03-23
Anticipated expiration: 2028-10-31
Also published as: CN101441956A

Abstract

The invention relates to an electromagnet control circuit for a low-voltage switching appliance, including an electromagnet, an external AC power input circuit, a rectification and filter circuit, a self-feedback pulse width modulation and IGBT drive circuit, a start-up delay circuit, an input voltage sampling circuit, and a control chip MCU circuit; signal transmission between the above circuits: self-feedback pulse width modulation and IGBT drive circuit, adjust the output pulse width according to the load of the electromagnet, control its pull-in and release, and the start-up delay circuit requires a large current for the moment of pull-in of the electromagnet , and when the current is kept small after the pull-in, adjust the output voltage pulse width by adjusting the feedback resistor value at the moment of pull-in, and provide a large start-up current for the electromagnet. When the start-up time is up, adjust the feedback resistor value to adjust the output voltage The pulse width provides a small current for the electromagnet, and the input voltage sampling circuit detects the input of the external AC power supply, and converts the voltage signal into a frequency model through the V/f conversion circuit, and transmits it to the control chip MCU.

Description

A kind of control circuit for electromagnet of low-tension switch electric appliance

Technical field

The present invention relates to a kind of control circuit for electromagnet of low-tension switch electric appliance, the use that matches with corresponding device for switching belongs to the low voltage electrical apparatus technology field.

Background technology

Control circuit for electromagnet is an important circuit of low-voltage electrical apparatus field contactor product class, and this circuit is controlled its adhesive or release by the control current of electromagnet, thereby makes the dynamic and static contact of contactor series products produce corresponding break-make motion.

At present, domestic most of device for switching control circuit for electromagnet adopts the simple break-make control of full voltage, and control is simple, and cost is low, but the electromagnet motoricity is big, causes that easily contact bounce causes contact to burn; The simple break-make of full voltage is controlled electromagnet energy consumption height in addition, and long-term heating power is serious.

China domestic a part of device for switching manufacturer, device for switching business men product control circuit for electromagnet employing electromagnet two-supply circuit altogether.Two-supply circuit refers to that electromagnet is divided into the adhesive power supply, keeps power supply two parts.Adopt big electric current power supply during startup, normally high pressure or full voltage power supply; Adopt little current DC power supply to keep enough holding forces during maintenance.Though this circuit has been distinguished startup and holding current, holding current is not sampled, to not numerical value sampling of input voltage, so electromagnet current can not change with the external voltage input.

External a part of device for switching manufacturer, control circuit for electromagnet adopts the electromagnet two-supply circuit.Be divided into the adhesive power supply, keep power supply two parts, adopted current feedback, electromagnet current can change with extraneous input voltage, but input voltage is not had the numerical value sampling, can't accurately control electromagnet current.

Chinese invention patent CN99122868 has the schematic diagram (as Fig. 1) by the magnet control equipment of the power circuit of electromagnet holding current power supply.Wherein (1) is electromagnet coil, and Va is added in (1) and goes up by T4 Control current size, and the electric current of T5 control R4 cut-offs, and R4 is a feedback resistance, and feedback signal passes to E2, and control chip (9) is exported adjusting according to feedback.This circuit has current feedback, does not have Va voltage detecting feedback.

Summary of the invention

The object of the present invention is to provide a kind of control circuit for electromagnet of low-tension switch electric appliance, this is the circuit that is used for electromagnet of low-tension switch electric appliance control, realizing startup, the retentive control of electromagnet, and can change the circuit of regulating magnet electric current magnet control with external voltage.

In order to achieve the above object, technical scheme of the present invention is: this control circuit for electromagnet comprises that self feed back pulse-width modulation and IGBT drive circuit, electromagnet start delay circuit, input voltage sample circuit, external ac power source input, rectification and filter circuit, control chip MCU, electromagnet.Through the power supply of external ac power source input, rectification and filter circuit supply with self feed back pulse-width modulation and IGBT drive circuit, electromagnet starts delay circuit, input voltage sample circuit, control chip MCU, electromagnet, the signal of input voltage sample circuit sampling is after control chip MCU handles, send self feed back pulse-width modulation and IGBT drive circuit drive magnet again, need the delayed startup delay circuit, by self feed back pulse-width modulation and IGBT drive circuit drive magnet again.

Beneficial effect of the present invention: this is a kind of circuit that is applicable to that electromagnet of low-tension switch electric appliance is controlled, and its current collection magnet constant current control, the electromagnet maintenance of startup time-delay back, input voltage sampling, the wide voltage power supply self-regulating function of electromagnet are in one.Use has a volume in low-tension switch electric appliance little, function is strong, high reliability features, make controlled electromagnet have good startup, retention performance, reduce the electromagnet energy consumption, reduce the electromagnet volume, enlarge work of electromagnet voltage, prolonging the work of electromagnet life-span, and make work of electromagnet more steady, is a kind of electronic circuit that promotional value and practical value are arranged.

Description of drawings

Fig. 1 is the schematic diagram of the magnet control equipment of prior art;

Fig. 2 is a control circuit for electromagnet of low-tension switch electric appliance hardware principle block diagram of the present invention;

Fig. 3 is control circuit for electromagnet of low-tension switch electric appliance self feed back pulse-width modulation of the present invention and IGBT drive circuit and starts the delay circuit schematic diagram;

Fig. 4 is a control circuit for electromagnet of low-tension switch electric appliance input voltage sample circuit schematic diagram of the present invention.

Embodiment

Below in conjunction with drawings and Examples the present invention is elaborated.

Fig. 1 is a patent of invention CN99122868 control circuit for electromagnet of low-tension switch electric appliance schematic diagram.Existing explanation no longer repeats in background technology.

With reference to Fig. 2, this is a control circuit for electromagnet of low-tension switch electric appliance hardware principle block diagram of the present invention.

Described control circuit for electromagnet comprises external ac power source input 1, current rectifying and wave filtering circuit 2, self feed back pulse-width modulation and IGBT drive circuit 3, starts delay circuit 4, input voltage sample circuit 5, control chip circuit 6, electromagnet 7.

Signal transmission between the foregoing circuit: external ac power source input 1, after carrying out rectification and Filtering Processing, rectification and filter circuit 2 be delivered to self feed back pulse-width modulation and IGBT drive circuit 3, this circuit is according to electromagnet 7 loading conditions, automatically regulate output pulse width, to reconcile the copped wave width of IGBT, thereby control is input to the current energy of electromagnet 7, controls adhesive, the release of electromagnet effectively.Start delay circuit 4 and be primarily aimed at the big electric current of electromagnet 7 adhesive moment needs, and keep the little situation of electric current after the adhesive, for distinguishing attract current and keep electric current, thereby adjust the output voltage pulsewidth by adjusting the feedback resistance resistance, start big electric current for electromagnet 7 provides in adhesive moment.Arrive when start-up time, adjust the output voltage pulsewidth, keep little electric current for electromagnet 7 provides thereby adjust the feedback resistance resistance.Input voltage sample circuit 5 detects external ac power source input 1, converts voltage signal to the frequency model by the V/f change-over circuit, is delivered to control chip MCU6.Whether control chip MCU6 is too high or too low according to the size decision voltage of input voltage, judges whether stop electromagnet 7 work.Thereby control chip MCU6 is by the adhesive or the disjunction of the working power control electromagnet 7 of conducting or shutoff self feed back pulse-width modulation and IGBT drive circuit 3.

With reference to Fig. 3, this is self feed back pulse-width modulation of the present invention and IGBT drive circuit and starts the delay circuit schematic diagram.

Described self feed back pulse-width modulation and IGBT drive circuit 3 exchange input AC1, AC2 and carry out rectification by D1.T1 carries out turn-on and turn-off to circuit.U1 with the control of voltage driving mode realization to T1, makes its conducting or shutoff by feedback signal.R04, R05 are feedback resistance, by the electric current variation generation voltage signal variation of R04, R05, export thereby this voltage signal variation feeds back to U1 voltage adjustment pulsewidth.Described startup delay circuit, during startup, powered on moment C03 voltage is lower than R08 voltage, and the U2 voltage ratio is back output high level, the Q1 conducting, R05 and R04 resistance in parallel diminishes, and becomes the startup feedback resistance.Arrive when starting delay time, C03 charging back voltage is higher than R08 voltage, and the U2 voltage ratio is the back output low level, and Q1 is by turn-offing, and R04 becomes feedback resistance separately, and it is big that the feedback resistance resistance becomes, feedback resistance when forming electromagnet and keeping.

With reference to Fig. 4, this is a control circuit for electromagnet of low-tension switch electric appliance input voltage sample circuit schematic diagram of the present invention.

Described input voltage sample circuit 5, supply voltage input signal (supply voltage input signal+,-

draw

2,4 pin from Fig. 2 rectifier D1 respectively) is decayed into small-signal after by R09, R10, R11 step-down, R12 is a sampling resistor, and C04 is that the AC signal of filter capacitor after with rectification filtered into direct current signal.U3 samples and is converted into frequency signal the C04 voltage signal and outputs to control chip.

Though the present invention describes with reference to the above embodiments; but those of ordinary skill in the art; will be appreciated that above embodiment is used for illustrating the present invention; should understand and wherein can make variations and modifications and do not break away from the present invention in a broad sense; so be not as limitation of the invention; as long as in connotation scope of the present invention, to the variation of above-described embodiment, the protection range that distortion all will fall into claim of the present invention.

Claims

1. A low-voltage switchgear electromagnet control circuit, comprising an electromagnet (7), an external AC power input circuit (1), a rectification filter circuit (2), is characterized in that: also includes self-feedback pulse width modulation and IGBT drive Circuit (3), start delay circuit (4), input voltage sampling circuit (5), control chip MCU circuit;

Signal transmission between the above circuits: the external AC power input circuit (1), after being rectified and filtered by the rectification and filtering circuit (2), is transmitted to the self-feedback pulse width modulation and IGBT drive circuit (3), and the self-feedback The pulse width modulation and IGBT drive circuit (3) automatically adjusts the output pulse width according to the load condition of the electromagnet (7) to adjust the chopping width of the IGBT, thereby controlling the current energy input to the electromagnet (7) and effectively controlling the electromagnetic The pull-in and release of the iron, the start-up delay circuit (4) is mainly aimed at the situation that the electromagnet (7) needs a large current at the moment of pull-in, and the maintenance current is small after the pull-in. Instantly adjust the output voltage pulse width by adjusting the resistance value of the feedback resistor to provide a large starting current for the electromagnet (7). Small current, input voltage sampling circuit (5) detects external AC power input (1), converts external AC power input voltage signal into frequency signal through v/f conversion circuit, and transmits to control chip MCU (6); control chip MCU ( 6) Determine whether the voltage is too high or too low according to the magnitude of the converted frequency signal, and determine whether to stop the operation of the electromagnet (7); the control chip MCU (6) self-feedback pulse width modulation and IGBT drive circuit by turning on or off The operating power of (3) thus controls the attraction or breaking of the electromagnet (7).

2. The electromagnet control circuit for low-voltage switchgear as claimed in claim 1, characterized in that: the self-feedback pulse width modulation and IGBT drive circuit (3) performs voltage pulse width modulation according to the feedback signal to control the IGBT conduction Or cut off, so as to control the current flowing through the electromagnet, so that the electromagnet is attracted or disconnected. the

3. The electromagnet control circuit for low-voltage switching devices according to claim 1, characterized in that: the start-up delay circuit (4) can distinguish start-up current and maintenance current during start-up. the