CN214705812U

CN214705812U - Contactor control circuit

Info

Publication number: CN214705812U
Application number: CN202120830056.5U
Authority: CN
Inventors: 不公告发明人
Original assignee: Mornsun Guangzhou Science and Technology Ltd
Current assignee: Mornsun Guangzhou Science and Technology Ltd
Priority date: 2021-04-21
Filing date: 2021-04-21
Publication date: 2021-11-12
Anticipated expiration: 2031-04-21

Abstract

The utility model relates to a contactor control circuit, on current double-barrelled series contactor control circuit's basis, specifically realized and optimal design have been carried out to the drive of switch tube, have solved the technical problem that wherein floats the switch tube and turn-off the existence fast, specifically, utilize opto-coupler electrical isolation and one-way transmission signal's characteristic, cooperation darlington pipe composite amplification effect, when having realized the quick release of contactor, can also make the energy recovery of contactor coil demagnetization to bus-bar capacitance.

Description

Contactor control circuit

Technical Field

The utility model relates to an electromagnetic system device such as contactor, in particular to control of electromagnetic system device such as contactor.

Background

Traditional electromagnetic system devices such as contactor comprise coil and iron core, and the working process divides three stage: a pull-in stage, a pull-in stage and a turn-off stage. In the pull-in stage, the coil generates enough electromagnetic force to pull in the contactor contact through large pull-in current. And in the holding stage, the holding current of the coil is about one tenth of the pull-in current, and the loss of the coil is increased due to the excessive holding current. In the off phase, the current in the coil is consumed so that the contactor contacts are opened, in which process the faster the current is consumed in the coil, the faster and more reliable the contactor is opened.

In the switching-off control process of the contactor, the specific method is that the opening spring of the contactor is indirectly controlled to be opened by controlling the demagnetization of the coil inductance of the contactor, so that the main contact is disconnected.

The contactor is usually connected with a high-current main power loop when in work, and the main contact generates an arc pulling phenomenon when in turn-off, so that sparks are generated, great potential safety hazards exist, and the contactor is easy to ignite and burn in places with severe environment. In addition, the contactor is shut down every time and all can burn a main contact, and in time, the contact can burn out along with the increase of turn-off number of times, seriously influences the life and the reliability of contactor, and electric arc can lead to the contactor main contact to inhale together even, makes the main power return circuit unable disconnection, has the heavy current to switch on continuously, burns out controlled device, causes more serious harm to personal safety, environmental safety, property safety etc.. Therefore, the turn-off speed of the contactor becomes a very critical technical index, and the longer the turn-off time is, the longer the arc drawing time is, and the greater the potential safety hazard is.

A solution of the prior art is proposed in chinese patent application with application number 201911066386.5 entitled "a contactor power saving control circuit and control method thereof", as shown in fig. 1.

The scheme controls the contactor in a PWM chopping mode, and the specific control strategy is as follows: and in the pull-in stage of the contactor, an upper tube TR1 and a lower tube TR2 are both opened, so that the large-current excitation of a coil L1 of the contactor is realized, and the contactor is pulled in rapidly. The contactor pull-in is finished and then the pull-in stage is started, the upper pipe TR1 is kept normally open, the lower pipe TR2 meets the requirements of low current and low power consumption of coil inductance by means of small duty ratio, degaussing voltage in the pull-in stage is only the forward conduction voltage drop of the diode D1, the current slope of the contactor coil L1 is low, fluctuation is small, stable pull-in of the contactor is achieved, and the risk of tripping of the contactor is reduced. After a turn-off signal is sent out, the upper tube TR1 and the lower tube TR2 need to be turned off quickly, degaussing energy of a contactor coil L1 is absorbed through the bus input filter capacitor Cin, and the contactor is released quickly.

The core idea of the circuit for realizing quick turn-off is as follows: the demagnetization voltage of the contactor coil L1 is increased when the contactor is turned off to increase the gradient of the current drop of the contactor coil L1, thereby reducing the time of the contactor turn-off release. In addition, according to the scheme, the degaussing voltage at two ends of the contactor coil L1 can be clamped to the sum of the voltage of the bus input filter capacitor Cin and the forward conduction voltage drops of the two diodes D1 and D2 at the maximum from the design point of view, and the stress risk of the rear-stage circuit caused by the overhigh voltage stress can be actively avoided. Meanwhile, the circuit is simple in structure, so that the performance and cost of the circuit are obviously superior to those of a mainstream scheme.

However, the circuit has some disadvantages, mainly: because the structure is a double-tube series structure, the upper tube TR1 floats on the ground, isolation driving is required to be adopted, the upper tube TR1 and the lower tube TR2 are not synchronous or complementary in a conventional PWM chopping control mode, the upper tube TR1 is required to be normally on during normal work, and the bus is required to be quickly turned off after power failure, so that the upper tube TR1 is difficult to drive and control, a specific driving mode is not mentioned in the patent application, the bootstrap capacitor is used for driving the upper tube TR1 to be the best choice due to the driving requirement, but the discharge speed of the bootstrap capacitor in the turn-off stage is very slow, the requirement of quickly turning off the upper tube TR1 cannot be met, and the control idea of increasing the demagnetization voltage of the contactor coil L1 to accelerate the release speed of the contactor cannot be achieved. In addition, the driving voltage on the bootstrap capacitor cannot be timely reduced after the turn-off signal is sent out, the upper tube TR1 can be enabled to work in a constant current region, the reliability is reduced, and the risk of failure of the upper tube TR1 is increased.

The technical scheme in the chinese patent application document with application number 201911142072.9 and invention name "a contactor coil isolation control circuit and isolation control method thereof" proposes a method for fast discharging bootstrap capacitor, as shown in fig. 2, the design idea is to control the on-state of an optocoupler at the off stage and connect bootstrap capacitor C1 for fast discharging, but the circuit also has disadvantages, mainly including: firstly, due to the existence of the optical coupling transmission ratio CTR, the phototriode on the secondary side of the optical coupling works in an amplification area, and the working state of saturated conduction cannot be achieved, so that the discharge speed is always limited to a certain extent, and the release speed of the contactor is directly limited; secondly, in the process that the driving voltage of the switching tube TR1 is slowly reduced, the Miller effect of the switching tube TR1 can be intensified, the turn-off loss of the switching tube is aggravated, and the failure risk of the switching tube is improved; finally, the circuit has no clamping function, and the voltage spike across the contactor coil L1 when turned off may cause stress risk to the later stage circuit.

SUMMERY OF THE UTILITY MODEL

Therefore, the technical problem to be solved by the utility model is that: the utility model provides a contactor control circuit can turn off the contactor fast, greatly reduces contactor turn-off release time delay, and still contains the isolation drive to the switch tube in the circuit.

The utility model provides an above-mentioned technical problem's technical scheme as follows:

a contactor control circuit, comprising: the circuit comprises an optocoupler U1, a capacitor C1, an NPN triode Q1, a switching tube TR1, a switching tube TR2, a diode D1, a diode D2, a positive input port VIN, a negative input port GND, a first control port CTRL1, a second control port CTRL2, a third control port CTRL3 and a fourth control port CTRL 4;

the drain of the switching tube TR1 is connected to the positive input port VIN and the cathode of the diode D1 at the same time, the gate of the switching tube TR1 is connected to one end of the capacitor C1, the collector of the transistor Q1, the 4-pin of the optocoupler U1 and the third control port CTRL3 at the same time, and the source of the switching tube TR1, the cathode of the diode D2, the other end of the capacitor C1 and the emitter of the transistor Q1 are connected together and then connected to one end of the contactor coil L1; the drain of the switching tube TR2 is connected with the anode of the diode D1 and then is connected with the other end of the contactor coil L1, the source of the switching tube TR2 is simultaneously connected with the negative input port GND and the anode of the diode D2, and the gate of the switching tube TR2 is connected with the fourth control port CTRL 4; a pin 1 of the optocoupler U1 is connected with a first control port CTRL1, a pin 2 of the optocoupler U1 is connected with a second control port CTRL2, and a pin 3 of the optocoupler U1 is connected with a base electrode of the triode Q1;

the positive input port Vin is used for being connected with the positive end of a power grid, and the negative input port GND is used for being connected with the negative end of the power grid; the first control port CTRL1, the second control port CTRL2, the third control port CTRL3, and the fourth control port are used for inputting control signals, and thus, the control transistor Q1, the switching tube TR1, and the switching tube TR2 are turned on and off.

Further, the technical scheme further includes a resistor R1, one end of the resistor R1 is simultaneously connected to the 4-pin of the optocoupler U1 and the collector of the transistor Q1, and the other end of the resistor R1 is simultaneously connected to one end of the capacitor C1 and the gate of the switching tube TR 1.

The utility model provides an above-mentioned technical problem still provides another technical scheme, as follows:

a contactor control circuit, comprising: the circuit comprises an optocoupler U1, a capacitor C1, a PNP triode Q1, a switching tube TR1, a switching tube TR2, a diode D1, a diode D2, a positive input port VIN, a negative input port GND, a first control port CTRL1, a second control port CTRL2, a third control port CTRL3 and a fourth control port CTRL 4;

the drain of the switching tube TR1 is connected to the positive input port VIN and the cathode of the diode D1, the gate of the switching tube TR1 is connected to one end of the capacitor C1, the emitter of the transistor Q1 and the third control port CTRL3, and the source of the switching tube TR1, the cathode of the diode D2, the other end of the capacitor C1, the collector of the transistor Q1 and the 3-pin of the optocoupler U1 are connected together and then connected to one end of the contactor coil L1; the drain of the switching tube TR2 is connected with the anode of the diode D1 and then is connected with the other end of the contactor coil L1, the source of the switching tube TR2 is simultaneously connected with the negative input port GND and the anode of the diode D2, and the gate of the switching tube TR2 is connected with the fourth control port CTRL 4; a pin 1 of the optocoupler U1 is connected with a first control port CTRL1, a pin 2 of the optocoupler U1 is connected with a second control port CTRL2, and a pin 4 of the optocoupler U1 is connected with a base electrode of the triode Q1;

the positive input port Vin is used for being connected with the positive end of a power grid, and the negative input port GND is used for being connected with the negative end of the power grid; the first control port CTRL1, the second control port CTRL2, the third control port CTRL3, and the fourth control port CTRL4 are configured to input a control signal, so as to control the on/off of the transistor Q1, the switching tube TR1, and the switching tube TR 2.

Furthermore, the technical scheme further includes a resistor R1, one end of the resistor R1 is simultaneously connected to an emitter of the transistor Q1, and the other end of the resistor R1 is simultaneously connected to one end of the capacitor C1 and a gate of the switching tube TR 1.

Compared with the prior art, the utility model discloses following beneficial effect has:

(1) on the basis of the prior art shown in fig. 1, an isolation driving circuit for an upper tube and a lower tube is designed, and a bootstrap capacitor in the isolation driving circuit has a very high discharge speed, so that ultra-fast turn-off of the upper tube is realized, the influence caused by the miller effect is reduced, and the loss of a switching tube is reduced;

(2) the contactor can be quickly turned off, so that the turn-off release delay of the contactor is greatly reduced, and the turn-off delay of the contactor is shortened by more than one time compared with that of the circuit shown in fig. 2;

(3) when the contactor is turned off, the demagnetizing voltage spike is clamped to the sum of the voltage of the input bus capacitor and the forward conduction voltage drops of the two diodes D1 and D2 through the diode D1 and the diode D2, so that the stress of a post-stage device can be protected, and the energy can be recycled to the bus input filter capacitor Cin;

(4) the circuit is simple, the device is universal in type selection, the control and the isolation are realized, the cost is low, and the operation is easy.

Drawings

FIG. 1 is a schematic diagram of a contactor control circuit according to one of the prior art;

FIG. 2 is a schematic diagram of a contactor control circuit according to a second prior art;

fig. 3 is a schematic diagram of the application of the contactor control circuit according to the first embodiment of the present invention;

fig. 4 is a schematic diagram of a contactor control circuit according to a second embodiment of the present invention;

fig. 5 is a schematic diagram of a contactor control circuit according to a third embodiment of the present invention.

Detailed Description

The utility model discloses an inventive concept is on the basis of current double-barrelled series connection contactor control circuit, has carried out concrete realization and optimal design to the drive of switch tube, has solved wherein the technical problem that the switch tube that floats to ground cuts off the existence fast, specifically, utilizes the characteristic of opto-coupler electrical isolation and unidirectional transmission signal, cooperates darlington pipe composite amplification effect, when having realized the quick release of contactor, can also make the energy recovery of contactor coil demagnetization to bus-bar capacitance. The circuit of the present invention will be described with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

First embodiment

Fig. 3 is the contactor control circuit application schematic diagram of the first embodiment of the present invention, as shown in the figure, inductance L1 therein is the contactor coil, and electric capacity Cin is the bus input filter capacitance, and electric capacity Cin is connected between the positive end of electric wire netting and the negative end of electric wire netting, and the contactor control circuit of this embodiment includes: the circuit comprises an optical coupler U1, a capacitor C1, an NPN triode Q1, a switching tube TR1, a switching tube TR2, a diode D1, a diode D2, a positive input port VIN, a negative input port GND, a first control port CTRL1, a second control port CTRL2, a third control port CTRL3 and a fourth control port CTRL 4.

The drain of the switching tube TR1 is connected to the positive input port VIN and the cathode of the diode D1 at the same time, the gate of the switching tube TR1 is connected to one end of the capacitor C1, the collector of the transistor Q1, the 4-pin of the optocoupler U1 and the third control port CTRL3 at the same time, and the source of the switching tube TR1, the cathode of the diode D2, the other end of the capacitor C1 and the emitter of the transistor Q1 are connected together and then connected to one end of the contactor coil L1; the drain of the switching tube TR2 is connected with the anode of the diode D1 and then is connected with the other end of the contactor coil L1, the source of the switching tube TR2 is simultaneously connected with the negative input port GND and the anode of the diode D2, and the gate of the switching tube TR2 is connected with the fourth control port CTRL 4; a pin 1 of the optocoupler U1 is connected with the first control port CTRL1, a pin 2 of the optocoupler U1 is connected with the second control port CTRL2, and a pin 3 of the optocoupler U1 is connected with a base electrode of the triode Q1.

The working principle of the contactor control circuit of the embodiment is as follows:

when the contactor works in a pull-in stage, synchronous control signals are input into the first control port CTRL1 and the second control port CTRL2, the control signal input into the first control port CTRL1 is equal to or smaller than the potential of the control signal input into the second control port CTRL2, the smaller specific potential value needs to ensure that no current flows through the primary side of the optocoupler U1, and the optocoupler U1 is in a turn-off state. The control signal inputted from the third control port CTRL3 will continuously charge the capacitor C1, so as to provide a stable driving voltage for the switching tube TR1, and the switching tube TR1 is turned on. The control signal inputted from the fourth control port CTRL4 will be continuously maintained at a high level, so that the switching tube TR2 is turned on, and thus the maximum current is used to provide energy for the excitation of the contactor coil until the contactor is completely closed.

When the contactor works in a holding stage, control signals input by the first control port CTRL1, the second control port CTRL2 and the third control port CTRL3 are the same as those in a pull-in stage, and the capacitor C1 stably and continuously provides driving energy for the switching tube TR1 to maintain the switching tube TR1 to be conducted. In order to reduce power consumption, the fourth control port CTRL4 controls the switching tube TR2 in a PWM chopping manner, and when the lower tube is turned off, the diode D1 demagnetizes the switching tube, so that the demagnetizing voltage is small, the current fluctuation of the contactor coil L1 is small, and the contactor is stably held.

When the contactor works in a turn-off stage, after a bus of the contactor is powered off, the fourth control port CTRL4 is immediately set low to turn off the switching tube TR2, meanwhile, a control signal input by the third control port CTRL3 immediately stops charging the capacitor C1, and as the switching tube TR1 is bootstrapped in a floating manner, the switching tube TR1 cannot be immediately turned off like the switching tube TR 2; the switching-off speed is far from sufficient by virtue of the fact that the switching tube TR1 dissipates the energy in the capacitor C1, which can result in the main contact of the contactor having sprung open and the switching tube TR1 not having been completely switched off.

At this time, the potential of the control signal input by the second control port CTRL2 is set low, so that the optocoupler U1 is turned on, and the phototransistor on the secondary side of the optocoupler U1 provides base current for the triode Q1.

After the transistor Q1 is added, the transistor Q1 and a phototriode on the secondary side of an optocoupler U1 form a Darlington composite tube structure, the current amplification factor is enhanced, the current on a capacitor C1 is extracted in an accelerated mode, the driving voltage is released, and a switching tube TR1 is turned off quickly, so that the design idea of recovering the demagnetization energy of a coil L1 of the contactor by utilizing a bus is realized, and meanwhile, because the demagnetization voltage is very high, a main contact of the contactor can be flicked quickly.

The following is the test data of the turn-off release delay of the circuit contactor shown in fig. 2 in this embodiment under the same test conditions and test environments:

as can be seen from the above data, the turn-off release delay time of the contactor is shortened by more than one time in this embodiment compared to the prior art contactor control circuit shown in fig. 2.

In addition, the structure of the double-tube series connection in the embodiment can also clamp the maximum value of the degaussing voltage to the sum of the voltage of the input bus capacitor and the forward conduction voltage drops of the two diodes D1 and D2, and actively avoids the stress risk of the rear-stage device caused by the overhigh voltage stress.

Second embodiment

Fig. 4 is an application schematic diagram of a contactor control circuit according to a second embodiment of the present invention, and as shown in the drawing, the difference is that the contactor control circuit according to this embodiment further includes a resistor R1 compared with the first embodiment. One end of the resistor R1 is simultaneously connected with the 4 pin of the optocoupler U1 and the collector of the triode Q1, and the other end of the resistor R1 is simultaneously connected with one end of the capacitor C1 and the grid of the switching tube TR 1.

The working principle of the present embodiment is the same as that of the first embodiment, and the difference is that after the resistor R1 is added, the current flowing through the secondary side phototransistor of the optocoupler U1 can be controlled, the energy discharged by the capacitor C1 is lost on the resistor R1, and the optocoupler U1 and the triode Q1 are protected. Meanwhile, the turn-off speed of the switching tube TR1 can be freely adjusted, so that the turn-off delay of the contactor can be better controlled.

Third embodiment

Fig. 5 is an application schematic diagram of a contactor control circuit according to a third embodiment of the present invention, and as shown in the drawing, the difference is that the NPN transistor Q1 in the contactor control circuit is replaced by a PNP transistor as compared with the second embodiment. At this time, the base of the triode Q1 is connected with the 4 pin of the optocoupler U1, the emitter of the triode Q1 is connected with one end of the first resistor R1, and the collector of the triode Q1 is simultaneously connected with the 3 pin of the optocoupler U1, one end of the capacitor C1, the cathode of the diode D2 and the source of the switching tube TR 1.

The PNP triode can also be used to replace the NPN triode to form a darlington composite structure, and the working principle of the circuit of the embodiment is the same as that of the second embodiment and is not described in detail.

It should be noted that the contactor of the present invention includes not only a narrow contactor, but also any electromagnetic system device such as a solenoid valve that needs to be turned off quickly. The foregoing is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the invention, and it should also be appreciated that the invention can be applied in other broader contexts. According to the above-mentioned content of the present invention, by using the common technical knowledge and conventional means in the field, without departing from the basic technical idea of the present invention, the present invention can also make other modifications, replacements or changes in various forms, such as replacing the NPN type triode Q1 in the first embodiment with a PNP type triode, and these modifications, replacements or changes all fall within the protection scope of the present invention.

Claims

1. A contactor control circuit, comprising: the circuit comprises an optocoupler U1, a capacitor C1, an NPN triode Q1, a switching tube TR1, a switching tube TR2, a diode D1, a diode D2, a positive input port VIN, a negative input port GND, a first control port CTRL1, a second control port CTRL2, a third control port CTRL3 and a fourth control port CTRL 4;

2. The contactor control circuit of claim 1, wherein: the circuit also comprises a resistor R1, wherein one end of the resistor R1 is simultaneously connected with the 4 pin of the optocoupler U1 and the collector of the triode Q1, and the other end of the resistor R1 is simultaneously connected with one end of the capacitor C1 and the grid of the switching tube TR 1.

3. A contactor control circuit, comprising: the circuit comprises an optocoupler U1, a capacitor C1, a PNP triode Q1, a switching tube TR1, a switching tube TR2, a diode D1, a diode D2, a positive input port VIN, a negative input port GND, a first control port CTRL1, a second control port CTRL2 and a third control port CTRL 3;

4. The contactor control circuit of claim 3, wherein: the circuit also comprises a resistor R1, wherein one end of the resistor R1 is simultaneously connected with an emitter of the transistor Q1, and the other end of the resistor R1 is simultaneously connected with one end of the capacitor C1 and a gate of the switching tube TR 1.