KR20180006009A - Apparatus and method of coil driving circuit for magnetic contactor with anti-release fuction - Google Patents

Abstract

The present invention relates to a coil drive device for a magnetic contactor, having an anti-release function of preventing abnormal release or recovering (reclosing) when a magnetic contactor is suspected of being released by an external environment factor of the magnetic contactor. The coil drive device comprises a release current detecting unit positioned between a mutually parallel connection point of a coil for magnetizing a fixed core and a discharge circuit for discharging the coil, and a release determining unit determining a release using the current detected by the release current detecting unit. When the release determining unit determines that a release condition of the contact point is likely to occur, the release determining unit readjusts the current flowing through the coil by causing a switch drive circuit to adjust a conduction time of a switch, thereby preventing abnormal release of the magnetic contactor which may be caused by variations of an applied voltage and an external impact. Therefore, it is possible to secure reliability of the magnetic contact and minimize loss in operation of an industrial system caused by an abnormal stoppage of a load.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil driving apparatus for an electromagnetic contactor having an anti-

The present invention relates to a coil drive device for an electromagnetic contactor, and more particularly, to prevent a problem that a contact of an electromagnetic contactor is released due to an external factor during operation of the electromagnetic contactor, To a magnetic contactor.

The magnetic contactor is widely used for control and protection of main circuit devices such as opening / closing of capacitors, resistance control, etc., in addition to being used for starting and stopping of motors. It protects fixed contacts, movable contacts and movable contacts A movable core for driving the contact column, a fixed core for sucking the movable iron core, an operation coil for winding the fixed iron core and magnetizing the fixed iron core, and a coil drive device for applying a current to the operation coil (coil driving circuit).

In the operation of the electromagnetic contactor, when power is applied to the coil driving device, the coil driving device controls the current flowing in the coil to magnetize the fixed iron core, and the fixed iron core that attracts the movable iron core is attracted to the contact Main contact and auxiliary contact) are closed. When an overvoltage or undervoltage of the power source applied to the coil drive device occurs, the current flowing through the coil is cut off and the contacts attached to the movable core are opened.

In the operation of the coil drive device, a relatively large current (input current) must be applied when the initial current for magnetizing the fixed core is applied. After the movable core is attracted to the fixed core, the magnetization of the fixed core is maintained At the same time, a relatively small current (holding current) should be applied to minimize the heat generation of the coil.

Since the conventional electromagnetic contactor coil drive apparatus detects only the magnitude of the applied voltage and determines the amount of control of the current applied to the coil, the variation of applied voltage such as transient voltage, instantaneous voltage drop, instantaneous starting load fluctuation, There is a problem in that an accident such as suction failure or contact release occurs due to impact due to impact caused by lightning or the like, resulting in an abnormal stop of the load, which can cause enormous damage to the operation of the industrial system connected to the load.

In order to solve the above problems, some prior arts have also proposed a method of confirming the open / close state of the contact point. However, these methods are required not only to reduce the cost competitiveness of the product due to a change in mechanism structure and addition of parts such as physical switches It is difficult to prevent the damage of the load due to the release of the magnetic contactor since it is possible to determine whether the contact is released after the contact is released.

The present invention relates to a coil drive apparatus having a function of enhancing the magnetic force of a fixed iron core by predicting a phenomenon of releasing a contact without adding a mechanism and a component in advance to solve the above problems, And to provide the improved electromagnetic contactor at a low cost.

According to an aspect of the present invention, there is provided an apparatus for driving a coil of an electromagnetic contactor, comprising: a surge / noise filter circuit (101) for reducing surges and noise of input power; A rectifying circuit (102) for converting the applied AC drive power source to DC; A switch 103 for determining a current flowing through the coil for magnetization of the fixed core; A switch driving circuit (104) for applying a pulse signal to the switch; A discharge circuit (105) for returning the excited current to the coil (20); An input voltage detecting circuit (106) for detecting a voltage converted into a direct current by the rectifying circuit for controlling the switch; An injection current determination unit 107 for determining an initial power-on time for initial magnetization of the fixed core; A holding current determination unit (108) for determining a holding current amount for maintaining magnetization of the fixed core; A release current detection circuit (110) located between the coil and the parallel connection point of the discharge circuit to detect release of the contact; And a release determining unit (120) for determining a release condition of the contact by using the current detected by the release current detection circuit.

The switch driving circuit 104 includes an input current determination unit 107 for determining an initial amount of applied current based on the input voltage information detected by the input voltage detection circuit 106; A holding current determination unit (108) for holding a magnetic force after the movable iron core is attracted to the fixed iron core; And the release determination unit 120 generates a drive pulse of the switch 103. [

The release determining unit 120 compares the coil current detected by the release current detection circuit 110 with the holding current command determined from the holding current determination unit 108 to determine whether or not the contact is released, To the switch driving circuit (104).

When the release determining unit 120 determines that the release of the contact is suspected or released, the switch driving circuit 104 resets the conduction time of the switch 103, By increasing the amount of current flowing, the magnetic force of the fixed iron core can be strengthened or the fixed iron core can be reintroduced.

According to the electromagnetic contactor coil drive apparatus of the present invention, since the abnormal release phenomenon of the contact point can be predicted by detecting the variation of the current applied to the coil, the electromagnetic contactor coil drive apparatus It is possible to prevent abnormal release phenomenon.

Further, even if the electromagnetic contactor is abnormally released, it is possible to quickly re-input the electromagnetic contactor, so that the loss in the operation of the industrial system due to the abnormal stop of the load can be minimized.

Further, in the implementation of the electromagnetic contactor coil drive apparatus of the present invention, only a relatively simple logic circuit is required, and a change in mechanism structure or an additional physical switch is not required, so that a high-quality electromagnetic contactor can be supplied at low cost.

1 is a view showing a configuration of a conventional electromagnetic contactor coil drive device.
2 is a view showing a configuration of an electromagnetic contactor coil drive device according to an embodiment of the present invention.
3 is a view for comparing the operation of the electromagnetic contactor according to the presence or absence of the release judging section of the present invention when releasing conditions occur.
4 is a view showing a configuration of a release determining unit and a switch driving circuit for activating a release preventing function in an electromagnetic contactor coil driving apparatus according to an embodiment of the present invention.
5 is a view showing a configuration of an electromagnetic contactor coil drive device according to another embodiment of the present invention.

It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

It is to be understood that the embodiments, and configurations, shapes, structures, and characteristics shown in the drawings are not intended to represent all of the technical ideas of the present invention and are not limited to the specific embodiments described herein, But should be understood to include all modifications, equivalents, and alternatives falling within the scope of the appended claims.

The singular presentation throughout the specification, unless the context clearly indicates otherwise, includes a plurality of representations, and the inclusion of any constituent element means that it may further include other constituents unless specifically stated otherwise. In the drawings, like reference numerals refer to the same or similar functions throughout the several views. In addition, in the entire specification, when a part is referred to as being 'connected' with another part, it is not only a case where it is directly connected, but also a case where it is indirectly connected with another element in between do.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order that those skilled in the art can easily carry out the present invention.

1 is a view showing a configuration of a conventional electromagnetic contactor coil drive apparatus. The electromagnetic contactor uses a coil drive device that controls the coil 20 wound around the fixed iron core so that a proper current flows in order to magnetize the fixed iron core.

A conventional electromagnetic contactor coil drive apparatus 10 includes a surge / noise filter circuit 11; A rectifying circuit (12); A switch 13; A switch driving circuit (14); A discharge circuit (15); An input voltage detection circuit (16); An injector current determiner 17; And a holding current determination unit 18.

The surge / noise filter circuit 11 absorbs the surge and noise components of the driving power applied to the input terminal. The rectifier circuit 12 rectifies the alternating-current power from which the surge and noise components are removed, It plays a role.

The switch 13 performs a turn-on and a turn-off to adjust the amount of the rectified DC power applied to the coil 20. The turn-on and turn-off of the switch 13 are determined by a pulse width modulation (PWM) signal originating from the switch drive circuit 14, and while the switch 13 is turned on, The current flowing through the coil 20 is increased through the switch 13 while the power source is being applied to the coil 20. [ When the switch 13 is turned off, the current flowing through the coil 20 decreases linearly while circulating through the discharge circuit 15 connected in parallel with the coil.

The operation of the switch 13 in the conventional general magnetic contactor is determined by the magnitude of the voltage of the rectified DC power source, and the input voltage detection circuit 16 detects the magnitude of the voltage of the DC power source. The input current determination unit 17 receives the magnitude signal of the power supply voltage from the input voltage detection circuit 16 at the initial stage of power application and calculates the turn-on time of the switch 13 for initialization of the fixed iron core , And transmits it to the switch driving circuit (14). The switch driving circuit 14 controls the turn-on state of the time switch 13 determined by the closing current determining unit 17. [ When the time determined by the applied current determination unit 17 is ended, the holding current determination unit 18 uses the magnitude of the DC voltage detected from the input voltage detection circuit 16 to determine the holding current And transmits it to the switch driving circuit 14. The switch driving circuit 14 performs pulse width modulation of the switch 13 in accordance with a control command output from the holding current determination unit 18. [

2 is a view showing a configuration of an electromagnetic contactor coil drive apparatus 100 according to an embodiment of the present invention. 2, the apparatus for driving a coil of an electromagnetic contactor according to an embodiment of the present invention includes a surge / noise filter circuit 101, a rectifying circuit 102, a switch 103, a switch driving circuit 104, Circuit 105, input voltage detection circuit 106; A holding current determination unit 107, a holding current determination unit 108, a release current detection circuit 110, and a release determination unit 120.

The surge / noise filter circuit 101 is connected in parallel to an input terminal to which drive power is applied to absorb surge and noise of the drive power.

The driving power source may be an alternating current power source or a direct current power source, and the rectifying circuit 102 is connected in parallel to a surge / noise filter to convert the driving power source to an alternating current.

The magnetization of the fixed core is controlled by adjusting the amount of current flowing through the coil 20, and the amount of current flowing through the coil is controlled by the turn-on and turn-off operations of the switch 103.

The turn-on and turn-off of the switch 103 are controlled by the switch driving circuit 104. As the turn-on duration of the switch 103 is longer, the current flowing through the coil 20 increases, As the turn-on interval of the switch 103 is short, the current flowing through the coil 20 decreases.

The discharge circuit 105 serves to return the current of the coil 20 during the turn-off period of the switch 103 to prevent magnetic flux saturation of the fixed core.

The input voltage detecting circuit 106 detects the magnitude of the driving power converted into the direct current by the rectifying circuit 102 and transmits it to the closing current determining unit 107 and the holding current determining unit 108.

The input current determination unit 107 determines the drive power application time for initial magnetization of the fixed core using the magnitude of the drive power detected by the input voltage detection circuit 106. The switch driving circuit 104 maintains the switch 103 in a conductive state during a turn-on time determined by the closing current determination unit 107.

The holding current determination unit 108 uses a magnitude of the driving power source detected by the input voltage detection circuit 106 to control the coil 20 for holding the magnetic force of the fixed core magnetized by the closing current determination unit 107 ) Is determined. At this time, the switch driving circuit 104 generates a pulse width modulation (PWM) signal for following the amount of current determined by the holding current determination unit 108, and controls the switch 103.

The release current detection circuit 110 detects the magnitude of the current flowing through the coil 20 when the holding current determination unit 108 operates and transmits the detection result to the release determination unit 120.

The release determining unit 120 compares the reference value of the coil current determined by the holding current determining unit 108 with the size information of the coil current detected by the release current detection circuit 110 to determine whether or not the contact is released And transmits an abnormal signal to the switch driving circuit 104 when release is suspected.

In the operation of the release determining unit 120, the difference between the reference value of the coil current determined by the holding current determining unit 108 and the magnitude of the coil current detected by the release current detecting circuit 110 falls within a certain range The release judging unit 120 judges this as an abnormal state.

FIG. 3 is a diagram comparing the operation of the electromagnetic contactor according to the presence or absence of the release determiner 120 when abnormal release conditions occur due to an external impact. 3 (a) shows the operation of the conventional electromagnetic contactor without the release determiner 120. FIG. Even when the contact is released due to an external shock, the conventional switch driving circuit 14 does not recognize this, and the output signal (switch driving signal) performs a pulse width modulation (PWM) operation in the same manner as in a normal sustain period Can be confirmed.

3 (b) shows the operation of the electromagnetic contactor to which the release determiner 120 of the present invention is applied. When an external shock occurs, the actual coil current detected by the release current detection circuit 110 rises and the difference between the coil current reference value, which is the output signal of the holding current detection unit 108, becomes the upper limit of the coil current upper limit The switch driving circuit 104 increases the conduction time of the switch according to the determination of the release determining unit 120. Thereby, the magnetic force for maintaining the contact point can instantaneously be raised, The release of the contact can be prevented.

4 is a diagram showing the configuration of the release determining unit 120 and the switch driving circuit 104 for activating the release preventing function in the electromagnetic contactor coil driving apparatus according to the embodiment of the present invention.

The release determiner 120 includes a differential current calculator 121, a release criterion calculator 122 and a release determiner 123. The release current detector 121 detects the coil current 111 detected by the release current detector 110, And a holding current reference value 109 determined by the holding current determining unit 108. [ The switch driving circuit 104 includes a reference wave generating unit 141, a carrier wave generating unit 142 and a comparator 143 for generating a pulse width modulation signal by comparing the reference wave generating unit 141 and the carrier wave generating unit 142.

The differential current calculator 121 calculates the difference between the coil current 111 and the holding current reference value 109 in operation of the release determiner 120 and transmits the result to the release determiner 123. The release criterion calculator 122 receives the retention current reference value 109, calculates a range of allowable current amount based on the retention current reference value 109, and transmits it to the release determiner 123.

When the output signal of the differential current arithmetic unit 121 is out of the range determined by the release reference arithmetic unit 122, the release determination unit 123 outputs a high (" High) signal.

The signal generated in the release determining section 123 is input to the reference wave generating section 141 of the switch driving circuit 104. The reference wave generating unit 141 receives the output signal of the release determining unit 123 and the holding current reference value 109.

In the operation of the reference wave generator 141, when the output of the release determiner 123 is low, the reference wave generator 141 outputs the input sustain reference value 109 And outputs a value equal to or larger than the maximum value of the carrier wave generation section 142 when the output of the release determination section 123 is high.

In operation of the switch driving circuit 104, the comparator 143 compares the output signal of the reference wave generating unit 141 with the output signal of the carrier generator 142 to generate a pulse width modulated signal. Here, the output signal of the carrier generator 142 may be triangular wave or sawtooth wave.

2, the release current detection circuit 110 is provided between the coil 20 and the discharge circuit 105. The coil current detection circuit 110 includes a coil 20, And is located between the interconnect lines.

100: A coil drive device for an electromagnetic contactor according to the present invention
103: Switch
104: Switch driving circuit
105: Discharge circuit
106: Input voltage detection circuit
107:
108:
110: Release current detection circuit
120: Release judge

Claims (4)

A release current detection circuit capable of detecting a current variation occurring upon release of the contactor contact;
A release judging unit for judging whether or not the release is based on the information detected by the release current detection circuit;
And a switch driving circuit for resetting the coil current when it is determined that the release phenomenon has occurred or is released when release is determined to be caused by the release current detection circuit and release determination unit
The method according to claim 1,
Wherein the release current detection circuit is located on a connection line between the coil and the discharge circuit, and at least one terminal is connected to the coil, and at least one terminal is connected to the discharge circuit.
The method according to claim 1,
The release determining unit compares the magnitude of the current detected by the release current detection circuit with the difference between the reference current determined by the holding current determination unit and determines that the difference is a release state, And outputs a current adjustment signal to the electromagnetic contactor.
The method according to claim 1,
Wherein the switch driving circuit includes a function of recognizing a re-input command signal output from the release current detector and re-adjusting the conduction time of the switch for re-charging.

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