CN210778408U

CN210778408U - Contactor power-saving control circuit

Info

Publication number: CN210778408U
Application number: CN201921881468.0U
Authority: CN
Inventors: 王小亮; 王志燊; 周灿荣
Original assignee: Mornsun Guangzhou Science and Technology Ltd
Current assignee: Mornsun Guangzhou Science and Technology Ltd
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2020-06-16
Anticipated expiration: 2029-11-04

Abstract

The utility model discloses a contactor economize on electricity control circuit, including first switch tube, second switch tube, first diode, second diode, first resistance. The contactor comprises three stages of attraction, attraction and disconnection in the working process, wherein in the attraction stage, two switch tubes are closed, a circuit absorbs energy from a power grid, and a large current flows through a coil of the contactor to enable a main contact to be attracted quickly; in the holding stage, the second switch tube is closed, the first switch tube samples the current flowing through the first switch tube through the first resistor to control the first switch tube to be intermittently closed and opened, and the contactor coil flows a small current to enable the contactor contact to keep a suction state and realize an energy-saving effect; in the turn-off stage, the two switching tubes are both switched off, the coil energy is returned to the power grid by a circuit formed by the two diodes, the current of the coil of the contactor is reduced to zero, the main contact of the contactor is rapidly switched off, and meanwhile, the energy recovery is realized.

Description

Contactor power-saving control circuit

Technical Field

The utility model relates to a contactor field, in particular to contactor economize on electricity control circuit.

Background

The traditional contactor consists of a coil and an iron core, and the working process is divided into three stages: a pull-in stage, a pull-in stage and a turn-off stage. In the attraction stage, the coil generates enough electromagnetic force to attract the contactor through large attraction 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.

The traditional contactor has no other control elements and can only limit the current through the impedance of the coil. In order to take account of the large current required for pull-in, the coil impedance cannot be designed to be too large. Therefore, in the process of holding the contactor, the current flowing through the coil is far greater than the current actually needed, the redundant energy is changed into the heat of the coil, the energy is wasted, the temperature of the coil is increased, the reliability is reduced, no release path exists in the energy of the coil in the turn-off stage, the induction voltage generated by the coil is too high, the rear-end device is damaged, if the follow current is added, the current in the coil is slowly reduced, the contact of the contactor cannot be flicked in time, and the reliability of the product is greatly reduced.

In order to solve the problem of large power consumption of the traditional contactor, a plurality of contactor power-saving circuits are provided. Fig. 1 is a schematic diagram of a common application of the power saving circuit, and the current of a contactor coil L1 is controlled by adjusting the duty ratio of a MOS transistor TR 1. The duty ratio of TR1 is large in the pull-in stage, and the duty ratio of TR1 is small in the pull-in stage, so that large current pull-in and small current pull-in of a coil of the contactor are realized, and the effect of energy conservation is achieved. The diode D1 provides a freewheeling circuit for the coil, and the low-impedance freewheeling circuit is beneficial to reducing the loss of the whole circuit during normal operation. In the turn-off stage, in order to turn off the contactor quickly, the current of the coil needs to be consumed quickly, but when the contactor is turned off, the coil energy can be consumed only through the freewheeling diode, and the voltage drop on the freewheeling diode is small, so that the coil energy is consumed slowly, and the contactor is turned off very slowly. In the traditional contactor product, the turn-off time is about 50ms, while the turn-off time of the contactor product added with the power-saving circuit can be increased to about 200ms, namely, the turn-off time is four times of the turn-off time of the contactor product. In some applications, the increase of the turn-off time may cause fatal problems, such as the control of a contactor with a motor rotating in a forward and reverse direction, and after the turn-off speed is reduced, the arc discharge time between main contacts of the contactor is prolonged, and the service life of the contactor is seriously threatened.

In order to realize the rapid turn-off function, it is necessary to increase the impedance of the coil freewheeling circuit when the contactor is turned off. It is common practice to switch the impedance of the freewheel loop with a switch. The existing contactor power-saving circuit with the rapid turn-off function has certain problems.

For example, in the patent of "a contactor coil control circuit" with publication number CN106024521B, the circuit application schematic diagram is shown in fig. 2. In the fast turn-off stage, the main power switch tube TR1 is turned off, and the coil current is consumed by the D1 and the fast turn-off circuit (i.e., the switch tube TR2) at a fast speed, so as to achieve the effect of fast turn-off. The circuit has the disadvantages that in the turn-off stage, the switching device of the rapid turn-off circuit works in an amplification area, and more energy is lost when a contactor coil continues to flow, on one hand, because the voltage for demagnetizing the contactor coil is lower, the turn-off time of the contactor is longer, the loss of the power-saving circuit in the turn-off stage is increased, and on the other hand, the temperature of the switching device of the rapid turn-off circuit is increased, and the reliability is reduced. Meanwhile, in the turn-off process of the scheme, almost all energy in the coil is consumed on the switching tube TR2, and on the occasion of frequent turn-on and turn-off, the switching tube TR2 can be heated excessively to be damaged, and energy waste is serious.

SUMMERY OF THE UTILITY MODEL

The utility model provides a technical problem that, provide a contactor economize on electricity control circuit, reduce contactor coil active power consumption for the turn-off speed of contactor, and electricity-saving appliance self loss is little to can realize energy-conserving, reliable purpose with coil energy feedback to electric wire netting.

The utility model discloses a contactor economize on electricity control circuit's technical scheme as follows:

a contactor power-saving control circuit is characterized in that: the current sampling device comprises a first switch tube K1, a second switch tube K2, a first diode D1, a second diode D2, a first current sampling device, a positive input port Vin +, a negative input port Vin-, a first control port P1, a second control port P2, a sampling port P3, a first connection port P4 and a second connection port P5;

one end of the second switch tube K2 is connected to the positive input port Vin + and the cathode of the first diode D1, and the other end of the second switch tube K2 is connected to the first connection port P4 and the cathode of the second diode D2; one end of the first switch tube K1 is connected to one end of the first current sampling device, and the other end of the first switch tube K1 is simultaneously connected to the second connection port P5 and the anode of the first diode D1; the other end of the first current sampling device is simultaneously connected with the negative input port Vin-and the anode of the second diode D2;

the positive input port Vin + is used for being connected with the positive end of the power grid, and the negative input port Vin-is used for being connected with the negative end of the power grid; the first connection port P4 is used for connecting one end of the contactor coil, and the second connection port P5 is used for connecting the other end of the contactor coil; the control port P1 is used for inputting a control signal to the first switch tube K1, and the control port P2 is used for inputting a control signal to the second switch tube K2; the sampling port P3 is connected to one end of the first switch tube K1, and is used for sampling the current flowing through the first switch tube K1 to obtain a sampling signal, and then controlling the control signal input by the first switch tube K1 through the sampling signal.

Preferably, the first switch tube K1 and the second switch tube K2 are N-type MOS tubes, P-type MOS tubes, NPN triodes, PNP triodes, thyristors, or controllable switching devices.

Preferably, the first current sampling device is a resistor or a current transformer.

The utility model discloses an above-mentioned contactor economize on electricity control circuit's control method, technical scheme is as follows:

when the contactor works in a pull-in stage, a first control port P1 inputs a control signal to control a first switch tube K1 to be closed, a second control port P2 inputs a control signal to control a second switch tube K2 to be closed, and the inductive current of a coil of the contactor flows through large current to realize the quick closing of a main contact of the contactor;

when the contactor works in a holding stage, a first control port P1 inputs a control signal to control a first switch tube K1 to be intermittently switched on and switched off, a second control port P2 inputs a control signal to control a second switch tube K2 to be switched on, and the inductive current of a coil of the contactor flows through a small current, so that the main contact of the contactor is kept to be switched on, and the energy-saving effect is realized;

when the contactor works in a turn-off stage, the first control port P1 inputs a control signal to control the first switch tube K1 to be switched off, the second control port P2 inputs a control signal to control the second switch tube K2 to be switched off, the coil of the contactor discharges rapidly, energy returns to a power grid, flowing current is reduced to zero, and the main contact of the contactor pops open rapidly.

Preferably, when the contactor operates in the pull-in phase and the contactor operates in the holding phase, the control signal input by the first control port P1 is a PWM signal, and the duty ratio of the contactor operating in the pull-in phase is greater than the duty ratio of the contactor operating in the holding phase.

Based on the above preferred scheme, it is further preferred that when the contactor operates in the pull-in stage and the contactor operates in the holding stage, one or both of the control signals input from the second control port P2 are PWM signals, and the PWM signals are synchronized with the PWM signals input from the first control port P1.

Preferably, when the contactor operates in the pull-in phase and the contactor operates in the holding phase, the control signal input from the second control port P2 is either or both a continuous high signal.

Preferably, when the contactor operates in the pull-in phase and the contactor operates in the holding phase, the control signal inputted from the second control port P2 is either or both the PWM and high-level mixed signal.

Preferably, when the contactor operates in the off-phase, the control signal input by the first control port P1 and the control signal input by the second control port P2 are both continuous low level signals.

It should be noted that the above "one or both" means that two phases are involved, and either one of the phases may be selected or both of the phases may be selected. For example, "when the contactor operates in the pull-in phase and the contactor operates in the pull-in phase, the control signal input from the second control port P2 is either or both of the continuous high level signals" means that there are three situations: (1) when the contactor works in a pull-in stage, the control signal input by the second control port P2 is a continuous high-level signal; (2) when the contactor works in the holding stage, the control signal input by the second control port P2 is a continuous high level signal; (3) when the contactor works in the pull-in stage and the contactor works in the pull-in stage, the control signals input by the second control port P2 are both continuous high level signals ".

The utility model discloses a theory of operation will carry out detailed analysis in the concrete embodiment part, and is not repeated here, the beneficial effects of the utility model are as follows:

in the closing stage of the contactor coil, the voltage of a power grid is used as the demagnetization voltage of the coil, so that the contactor coil is demagnetized quickly, and the contactor is electrified and disconnected quickly; and the coil energy can also be fed back to the power grid through the freewheeling diode, so that the turn-off speed of the contactor can be increased under the condition that the main power circuit device is not changed, the active power consumption is reduced, and the coil excitation energy is recovered, so that the contactor is energy-saving and has strong reliability.

Drawings

FIG. 1 is a schematic diagram of a prior art contactor power saving circuit without a fast turn-off function;

FIG. 2 is a schematic diagram of a prior art contactor power saving circuit with a fast turn-off function;

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

fig. 4 is a control timing diagram of the contactor node control circuit according to the embodiment of the present invention.

Detailed Description

The utility model discloses the design does: the contactor comprises the following components in the working process: three stages of suction, holding and closing. The utility model provides a contactor economize on electricity control circuit includes first switch tube, second switch tube, first diode, second diode, first resistance, and the mode is: three working states of excitation, holding and demagnetization correspond to three working stages of the contactor. In the excitation stage, the first switch tube and the second switch tube are closed, the circuit absorbs energy from a power grid, and a large current flows through a coil of the contactor, so that the main contact is quickly attracted; in the holding stage, the second switch tube is closed, the first switch tube samples the current flowing through the first switch tube through the first resistor to control the first switch tube to be intermittently closed and opened, and the contactor coil flows a small current to ensure that the contactor contact keeps a suction state and realize the energy-saving effect; in the demagnetization stage, the first switch tube and the second switch tube are disconnected, the circuit returns the coil energy to the power grid through a path formed by the first diode and the second diode, the current of the coil of the contactor is reduced to zero, the main contact of the contactor is rapidly disconnected, and meanwhile energy recovery is achieved.

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.

Fig. 3 shows the utility model discloses an embodiment contactor economize on electricity control circuit uses the schematic diagram, the utility model discloses a contactor economize on electricity control circuit includes first switch tube K1, second switch tube K2, first diode D1, second diode D2, first resistance R1, positive input port Vin +, negative input port Vin-, first control port P1, second control port P2, third control port P3, first connection port P4 and second connection port P5, fig. 3 is the applied schematic diagram, consequently, the one end and the first connection port P4 with contactor coil L have been connected, the other end and the second connection port P5 with contactor coil L have been connected.

Other specific connection relationships of fig. 3 are: the positive input port Vin + is connected with the positive end of a power grid, one end of a second switch tube K2 and the cathode of a first diode D1, the other end of the second switch tube K2 is connected with the cathode of a second diode D2 and one end of a contactor coil, the anode of the first diode D1 is connected with the other end of a first switch tube K1 and the other end of the contactor coil, a third control port P3 is connected with one end of the first switch tube K1 and one end of a first contact resistor R1, the negative input port Vin-is connected with the other end of a first resistor, a first control port P1 is connected with the first switch tube K1, and a second control port P2 is connected with the control end of the second switch tube K2.

Following combine fig. 3 the utility model discloses contactor node control circuit uses the schematic diagram, and fig. 4 the utility model discloses a contactor node control circuit's control sequence diagram, as follows to the theory of operation analysis of this embodiment:

(1) the contactor works in the pull-in stage, and the contactor coil is in an excitation state, which corresponds to t0 to t1 in fig. 4: at an initial time t0, power is input and powered on, in fig. 3, the first control port P1 continuously outputs a PWM signal to control the first switch tube K1 to be closed, the second control port P2 outputs a high level to continuously conduct the second switch tube K2, the first switch tube K1 and the second switch tube K2 are driven to be at the high level, the positive input port Vin + charges the contactor coil through a path formed by the second switch tube K2, the contactor coil L, the first switch tube K1 and the first resistor R1, and the contactor coil inductor completes excitation at the time t1 and flows a large current.

The duty ratio of the PWM signal of the control port P1 is kept to be maximum (the current is larger when the duty ratio is closer to 1, and the attraction of the main contact is faster), the current is maximum in the attraction stage, and the effect of quickly and reliably closing the contact of the contactor is realized;

(2) the contactor works in the holding stage, the contactor coil current is in the holding state, and the current corresponds to t1 to t2 in fig. 4: after the contactor contact is attracted at the time t1, the duty ratio of the PWM signal of the control port P1 is reduced, and the control port P2 outputs a high level to continuously conduct the second switch tube K2. When the PWM signal of the control port P1 outputs a high level, the first switching tube K1 is closed; when the PWM signal of the control port P1 is output at a low level, the first switch tube K1 is disconnected, the inductive current flowing through the contactor coil is reduced, the inductor of the contactor coil is incompletely demagnetized through a path formed by the first diode D1 and the second switch tube K2, the contactor coil flows through a small current, the inductive loss of the contactor coil is reduced, and the contactor contact is kept to be reliably closed.

It should be noted that, the control signal of the second control port P2 in the (1) stage and the (2) stage may also be a PWM signal synchronized with the first control port P1, and when the second control port P2 is a PWM signal, the energy of the contactor coil flows through a path formed by the first diode D1, the positive input port Vin +, the grid, the negative input port Vin-, and the second diode D2, and the object of the present invention is also achieved.

(3) The contactor works in a turn-off stage, a contactor coil is in a demagnetizing state, corresponding to t2 to t3 in fig. 4, input of a positive input port Vin + is stopped at t2, a control port P1 outputs a low level to continuously disconnect a first switching tube K1, a second control port P2 outputs a low level to continuously disconnect a second switching tube K2, and the contactor coil is connected with a power grid through a passage formed by a first diode D1, a second diode D2, the positive input port Vin + and a negative input port Vin-. Moreover, since energy is consumed through the input grid, this part of energy is fed back to the grid, whereas the conventional electricity saver mentioned in the background art and the electricity saver in the CN106024521B patent are lost by converting this energy into heat energy. Therefore the utility model discloses can not only realize that the quick turn-off of contactor can also reach energy-conserving effect.

In this embodiment, the specific implementation manner of the second switch tube K2 and the first switch tube K1 may be an N-type MOS transistor, a P-type MOS transistor, an NPN triode, a PNP triode, or any controllable switch device.

The above is only the preferred embodiment of the present invention, it should be noted that the above preferred embodiment should not be considered as the limitation of the present invention, and for those skilled in the art, it is within the spirit and scope of the present invention that several equivalent substitutions, improvements and decorations can be made, such as replacing the first resistor R1 in fig. 3 with a current transformer, etc., replacing the control signal of the control port P2 with a signal of PWM mixed with high level, etc., and these equivalent substitutions, improvements and decorations should also be considered as the protection scope of the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A contactor power-saving control circuit is characterized in that: the current sampling device comprises a first switch tube K1, a second switch tube K2, a first diode D1, a second diode D2, a first current sampling device, a positive input port Vin +, a negative input port Vin-, a first control port P1, a second control port P2, a sampling port P3, a first connection port P4 and a second connection port P5;

2. The contactor power saving control circuit of claim 1, wherein: the first switch tube K1 and the second switch tube K2 are N-type MOS tubes, P-type MOS tubes, NPN triodes, PNP triodes, thyristors or controllable switching devices.

3. The contactor power saving control circuit of claim 1, wherein: the first current sampling device is a resistor or a current transformer.