阅读说明：本技术 一种接触器节电电路 (Contactor power-saving circuit ) 是由 不公告发明人 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种接触器节电电路,在现有的双管接触器节电电路的基础上,增加驱动电路,接触器节电电路中包括的开关管Q1连接于直流母线正端与接触器线圈一端之间、包括的开关管Q2连接于直流母线负端与接触器线圈另一端之间,该驱动电路在电路起机阶段,利用母线电压实现开关管Q1的正常开通,使得接触器在直流母线电压下励磁,相比于传统方案可大幅度降低开关管Q1起机阶段的损耗,并且在起机阶段还完成自举电容的充电,后续过程中能够持续为开关管Q1提供驱动电压。本发明能实现起机阶段,开关管Q1的栅源极驱动电压在100nS以内从0V升高到12V,实现了开关管Q1的正常启动,同时MOS管损耗非常低,并且电路简单,容易实施。(The invention discloses a contactor power-saving circuit, which is additionally provided with a driving circuit on the basis of the existing double-tube contactor power-saving circuit, wherein a switching tube Q1 included in the contactor power-saving circuit is connected between the positive end of a direct-current bus and one end of a contactor coil, and a switching tube Q2 included in the contactor power-saving circuit is connected between the negative end of the direct-current bus and the other end of the contactor coil, and the driving circuit utilizes the bus voltage to realize the normal opening of the switching tube Q1 in the starting stage of the circuit, so that a contactor is excited under the direct-current bus voltage, compared with the traditional scheme, the loss of the switching tube Q1 in the starting stage can be greatly reduced, the charging of a bootstrap capacitor is also completed in the starting stage, and the driving voltage can be continuously provided for the switching tube Q1 in the subsequent process. The invention can realize the startup stage, the grid-source electrode driving voltage of the switching tube Q1 is increased from 0V to 12V within 100nS, the normal start of the switching tube Q1 is realized, meanwhile, the MOS tube loss is very low, and the circuit is simple and easy to implement.)

1. A contactor power saving circuit comprising: a switching tube Q1, a switching tube Q2, a capacitor C1, a diode D1, a diode D2, a diode D3 and a diode D4;

the drain of the switching tube Q1 is used for connecting the positive end of a direct current bus, the source of the switching tube Q1 is used for connecting one end of a contactor coil, the drain of the switching tube Q2 is used for connecting the other end of the contactor coil, the source of the switching tube Q2 is used for connecting the negative end of the direct current bus, the anode of the diode D1 is connected with the drain of the switching tube Q2, the cathode of the diode D1 is connected with the drain of the switching tube Q1, the anode of the diode D2 is connected with the source of the switching tube Q2, the cathode of the diode D2 is connected with the source of the switching tube Q1, the anode of the diode D4 is used for connecting a pin FO for inputting a fast turn-off signal, the cathode of the diode D4 is simultaneously connected with one end of a capacitor C1 and the anode of the diode D3, the cathode of the diode D3 is connected with the gate of the switching tube Q1, the other end of the capacitor C1 is connected with the drain of the switching tube Q2, and the gate of the switching tube Q2 is used for inputting a driving voltage signal gate _ L;

it is characterized by also comprising: the diode D5, the capacitor C2, the capacitor C3 and the resistor R2;

the anode of the diode D5 is connected with the positive input end of the direct current bus, the cathode of the diode D5 is connected with one end of the capacitor C3, the other end of the capacitor C3 is connected with the grid of the switch tube Q1, the resistor R2 is connected in parallel with the two ends of the capacitor C3, and the capacitor C2 is connected between the grid and the source of the switch tube.

2. The contactor power saving circuit of claim 1, further comprising: the optical coupler OPT2, the one end of electric capacity C3 is connected to the one end of resistance R2, and the collector of the triode in optical coupler OPT2 is connected to the other end of resistance R2, and the other end of electric capacity C3 is connected to the projecting pole of triode in optical coupler OPT2, and the positive pole of diode in optical coupler OPT2 is used for inputing mains voltage VDD, and the negative pole of diode in optical coupler OPT2 is used for connecting the pin FO of the quick turn-off signal of input.

3. The contactor power saving circuit according to claim 1 or 2, further comprising: the optical coupler OPT and the resistor R1, the one end of electric capacity C2 is connected to the collector of triode in the optical coupler OPT, and electric capacity C2's the other end is connected to the projecting pole of triode in the optical coupler OPT, and the positive pole of diode is used for the input mains voltage VDD in the optical coupler OPT, and the negative pole of OPT diode is connected resistance R1's one end in the optical coupler, and the other end of resistance R1 is used for connecting the quick pin FO of turn-off signal of input.

Technical Field

The invention relates to the field of contactors, in particular to a contactor power-saving 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; in the holding stage, the holding current of the coil is about one tenth of the holding 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 conventional contactor has no other control elements and can only limit current through the impedance of the coil, and fig. 1 shows a contactor circuit model which is composed of L, CL and RL, wherein L is the contactor coil, RL is the internal resistance of the contactor coil, and CL is the turn-to-turn capacitance of the contactor 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 conventional contactor, some contactor power saving circuits are provided, and fig. 2 shows a power saving circuit of a conventional double-tube contactor, which includes: a switching tube Q1, a switching tube Q2, a capacitor C1, a capacitor C2, a diode D1, a diode D2, a diode D3 and a diode D4; the drain of the switch tube Q1 is used for connecting the positive end of the direct current bus, the source of the switch tube Q1 is used for connecting one end of the contactor coil, the drain of the switch tube Q2 is used for connecting the other end of the contactor coil, the source of the switch tube Q2 is used for connecting the negative end of the direct current bus, the anode of the diode D1 is connected with the drain of the switch tube Q2, the cathode of the diode D1 is connected with the drain of the switch tube Q1, the anode of the diode D2 is connected with the source of the switch tube Q2, the cathode of the diode D2 is connected with the source of the switch tube Q1, the anode of the diode D4 is used for connecting the pin FO for inputting the fast turn-off signal, the cathode of the diode D4 is simultaneously connected with one end of the capacitor C1 and the anode of the diode D3, the cathode of the diode D3 is connected with the gate of the switch tube Q1, the other end of the capacitor C1 is connected with the drain of the switch tube Q2, the gate of the switch tube Q2 is connected with the gate of the driving voltage gate _ L, and the capacitor C2 is connected in parallel between the source of the gate Q1 and the gate.

The working principle of the circuit shown in fig. 2 is that the capacitor C1 is a bootstrap capacitor of the switching tube Q1, and the charging of the capacitor C1 can be completed through a charging loop formed by the diode D4, the capacitor C1 and the switching tube Q2, so as to provide a driving voltage for the switching tube Q1; the diode D1 is a freewheeling diode for freewheeling the contactor coil when the switching transistor Q2 is turned off.

The contactor power-saving circuit adopts a double-tube scheme, aims to realize energy recovery through two freewheeling diodes, further saves power, reduces consumption and improves the reliability of a product, and has the problem that a switching tube Q1 is damaged in practical application.

Those skilled in the art think that in the startup phase of the contactor, the voltage across the energy storage capacitor C2 is large enough to serve as the gate-source voltage Vgs of the switching tube Q1, so as to smoothly open the switching tube Q1. However, after extensive and intensive research, the inventors of the present application found that, in the startup phase, when the voltage Vgs of the gate-source voltage of the switching tube Q1 is increased, the voltage Vin at the positive terminal of the dc bus is applied to the source of the switching tube Q1 through the switching tube Q1, and then the source voltage Vs of the switching tube Q1 gradually increases, and when the voltage Vs is higher than the voltage Vgs, the charging circuit of the energy storage capacitor C2 disappears, and the gate-source voltage Vgs of the switching tube Q1 cannot be increased to the conducting threshold of the switching tube Q1 in the switching state, so that the switching tube Q1 of the contactor cannot operate in the switching state in the startup phase, resulting in high loss.

Fig. 3 is a simulation diagram showing the operation timing sequence of the switching tube Q1 in the circuit shown in fig. 2, fig. 4 is an enlarged diagram of the timing diagram of fig. 3 when the switching tube Q1 is at the startup stage, and it can be seen from fig. 4 that the driving voltage of the switching tube Q1 at the startup stage is only 4V, so the reason analysis described above is verified, that is, when the switching tube Q2 of the contactor power saving circuit shown in fig. 2 is turned on, the switching tube Q1 is in the off state, at this time, a 15V voltage signal is input through the pin FO to charge the bootstrap capacitor C1, actually, the voltage Vgs of the gate-source capacitor C2 of the switching tube Q1 cannot reach 15V, and the switching tube Q1 is stuck in the sub-threshold state of 3-4V, so that the switching tube Q1 is highly worn and is easily damaged.

It is noted that the above information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information constitutes prior art already known to a person skilled in the art.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide a power saving circuit of a contactor, which adopts a double-tube scheme to reduce the loss of a switching tube Q1 in the startup stage of a power saver of the contactor.

The contactor power-saving circuit adopts a double-tube contactor power-saving circuit structure, the circuit comprises a switch tube Q1 and a switch tube Q2, the switch tube Q1 is connected between the positive end of a direct-current bus and one end of a contactor coil, and the switch tube Q2 is connected between the negative end of the direct-current bus and the other end of the contactor coil.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a contactor power saving circuit comprising: a switching tube Q1, a switching tube Q2, a capacitor C1, a diode D1, a diode D2, a diode D3 and a diode D4;

the drain of the switching tube Q1 is used for connecting the positive end of a direct current bus, the source of the switching tube Q1 is used for connecting one end of a contactor coil, the drain of the switching tube Q2 is used for connecting the other end of the contactor coil, the source of the switching tube Q2 is used for connecting the negative end of the direct current bus, the anode of the diode D1 is connected with the drain of the switching tube Q2, the cathode of the diode D1 is connected with the drain of the switching tube Q1, the anode of the diode D2 is connected with the source of the switching tube Q2, the cathode of the diode D2 is connected with the source of the switching tube Q1, the anode of the diode D4 is used for connecting a pin FO for inputting a fast turn-off signal, the cathode of the diode D4 is simultaneously connected with one end of a capacitor C1 and the anode of the diode D3, the cathode of the diode D3 is connected with the gate of the switching tube Q1, the other end of the capacitor C1 is connected with the drain of the switching tube Q2, and the gate of the switching tube Q2 is used for inputting a driving voltage signal gate _ L;

it is characterized by also comprising: the diode D5, the capacitor C2, the capacitor C3 and the resistor R2;

the anode of the diode D5 is connected with the positive input end of the direct current bus, the cathode of the diode D5 is connected with one end of the capacitor C3, the other end of the capacitor C3 is connected with the grid of the switch tube Q1, the resistor R2 is connected in parallel with the two ends of the capacitor C3, and the capacitor C2 is connected between the grid and the source of the switch tube.

Further, the contactor power saving circuit further comprises: the optical coupler OPT2, the one end of electric capacity C3 is connected to the one end of resistance R2, and the collector of the triode in optical coupler OPT2 is connected to the other end of resistance R2, and the other end of electric capacity C3 is connected to the projecting pole of triode in optical coupler OPT2, and the positive pole of diode in optical coupler OPT2 is used for inputing mains voltage VDD, and the negative pole of diode in optical coupler OPT2 is used for connecting the pin FO of the quick turn-off signal of input.

Further, the contactor power saving circuit further comprises: the optical coupler OPT and the resistor R1, the one end of electric capacity C2 is connected to the collector of triode in the optical coupler OPT, and electric capacity C2's the other end is connected to the projecting pole of triode in the optical coupler OPT, and the positive pole of diode is used for the input mains voltage VDD in the optical coupler OPT, and the negative pole of OPT diode is connected resistance R1's one end in the optical coupler, and the other end of resistance R1 is used for connecting the quick pin FO of turn-off signal of input.

The working principle of the invention will be analyzed and explained by combining with the specific embodiment, and the beneficial effects of the invention are as follows:

in the startup stage, the gate-source electrode driving voltage of the switching tube Q1 is increased from 0V to 12V within 100nS, so that the normal starting of the switching tube Q1 is realized, and meanwhile, the MOS tube loss is very low.

The circuit is simple and easy to implement.

Drawings

FIG. 1 is a contactor circuit model;

FIG. 2 is a prior art dual tube contactor power saving circuit;

FIG. 3 is a simulation diagram of the operation timing of the switch Q1 in the circuit of FIG. 2;

FIG. 4 is an enlarged view of the timing diagram of FIG. 3 showing the switch Q1 at the start-up stage;

FIG. 5 is a circuit diagram of a first embodiment of the present invention;

FIG. 6 is a simulation diagram of the operation timing of the switch Q1 in the circuit of FIG. 5;

FIG. 7 is an enlarged view of the timing diagram of FIG. 6 showing the switch Q1 at the start-up stage;

FIG. 8 is a circuit diagram of a second embodiment of the present invention;

FIG. 9 is a circuit diagram of a third embodiment of the present invention.

Detailed Description

In order to make the invention more clearly understood, the invention is further described in detail below with reference to the attached drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

First embodiment

Fig. 5 is a circuit diagram of a first embodiment of the present invention, which is different from fig. 2 in that the circuit diagram further includes a switching tube driving circuit composed of a diode D5, a capacitor C2, a capacitor C3, and a resistor R2, an anode of the diode D5 is connected to the positive input terminal of the dc bus, a cathode of the diode D5 is connected to one end of the capacitor C3, the other end of the capacitor C3 is connected to a gate of the switching tube Q1, the resistor R2 is connected in parallel to two ends of the capacitor C3, and the capacitor C2 is connected between the gate and the source of the switching tube.

The working principle of the first embodiment is as follows:

in the startup phase, the switching tube Q2 is turned on, the diode D5, the capacitor C3, the capacitor C2 and the inter-turn capacitor CL of the contactor coil form a charging loop, the dc bus voltage is loaded to the diode D5, the capacitor C3, the capacitor C2 and the inter-turn capacitor CL of the contactor coil, and the voltage divided by the capacitor C2 is higher through capacitor voltage division to realize normal conduction of the switching tube Q1, so that the conduction loss of the switching tube Q1 is reduced, that is, in the startup phase, when the switching tube Q2 is conducted, the driving voltage is provided for the switching tube Q1 through the dc bus to enable the switching tube Q1 to work normally. If the switching tube Q1 is not normally conducted, and a high voltage difference Vds exists in the drain-source electrode of the switching tube Q1, then the capacitor C2 can be charged through a loop formed by the diode D5, the resistor R2 and the capacitor C2, so that the gate-source voltage Vgs of the MOS tube Q1 is increased until the drain-source voltage difference Vds of the switching tube Q1 is lower than the gate-source voltage difference Vgs thereof. The resistor R2 has an external function, namely after the switching tube Q1 is conducted, the capacitor C3 is discharged through the resistor R2, so that the switching tube Q1 can be normally conducted when the contactor is repeatedly switched on and switched off;

in addition, in the startup stage, the diode D4, the capacitor C1, and the switching tube Q2 form another charging loop to complete charging of the bootstrap capacitor C1 and maintain the gate-source driving voltage of the switching tube Q1 after startup.

Fig. 6 is a simulated waveform diagram of the operating timing of the switching transistor Q1 in this embodiment, and fig. 7 is an enlarged diagram of the timing diagram of fig. 6 when the switching transistor Q1 is in the startup phase, and as can be seen from fig. 7, in the startup phase, the switching transistor Q1 is normally driven, the gate-source voltage Vgs of the switching transistor Q1 is increased from 0V to 12V within 100nS, and meanwhile, the MOS transistor loss is very low, so that the purpose of solving the driving problem of the switching transistor Q1 is achieved.

Second embodiment

As shown in fig. 8, a circuit diagram of a second embodiment of the present invention is shown, and this embodiment is different from the first embodiment in that the present invention further includes an optocoupler OPT2, one end of a resistor R2 is connected to one end of a capacitor C3, the other end of the resistor R2 is connected to a collector of a transistor in the optocoupler OPT2, an emitter of the transistor in the optocoupler OPT2 is connected to the other end of the capacitor C3, an anode of a diode in the optocoupler OPT2 is used for inputting a power supply voltage VDD, and a cathode of the diode in the optocoupler OPT2 is connected to a pin FO for inputting a fast turn-off signal.

In the embodiment, the capacitor C3 is discharged through an optical coupler OPT2, and the working principle is analyzed as follows:

when a fast turn-off signal input by FO is high, a diode in the optocoupler OPT2 is cut off in a reverse direction, the secondary side of the optocoupler OPT2 is in a high-impedance state, and at the moment, the driving voltage is provided for the switching tube Q1 through the voltage division of a capacitor C3, a capacitor C2 and a turn-to-turn capacitor CL of a contactor coil;

when the fast turn-off signal input by FO is low, the diode in the optical coupler OPT2 is conducted in the forward direction, the secondary side of the optical coupler OPT2 is in a short-circuit state, at the moment, the capacitor C3 discharges through the resistor R2, the charge returns to zero, the capacitor C2 can be divided into enough high voltage when the switch is rapidly and repeatedly turned on and off, the switch tube Q1 can normally work, and the switch tube Q1 is suitable for occasions requiring rapid switch on and off.

It should be noted that, as an equivalent alternative to this embodiment, the opto-coupler OPT2 may be exchanged with the resistor R2.

Third embodiment

As shown in fig. 9, a circuit diagram of a third embodiment of the present invention is shown, and the present embodiment is different from the second embodiment in that the present embodiment further includes an optocoupler OPT and a resistor R1, a collector of a transistor in the optocoupler OPT is connected to one end of a capacitor C2, an emitter of the transistor in the optocoupler OPT is connected to the other end of a capacitor C2, an anode of a diode in the optocoupler OPT is used for inputting a power voltage VDD, a cathode of an OPT diode in the optocoupler is connected to one end of a resistor R1, and the other end of the resistor R1 is connected to a pin FO for inputting a fast turn-off signal, so as to control turn-on of the OPT diode in the optocoupler.

The working principle of the embodiment is different from that of the second embodiment in that the optocoupler OPT and the resistor R1 can realize the fast turn-off of the switching tube Q1, and since the other end of the resistor R1 inputs a control signal synchronous with the voltage signal gate _ H, a diode in the optocoupler is in forward conduction when the voltage signal gate _ H changes from a high level to a low level, at this time, a triode in the optocoupler is in conduction, and discharges the capacitor C2 between the gate and the source of the switching tube Q1, so that Vgs is reduced to the conduction threshold, the switching tube Q1 is turned off, and the function of fast turn-off of the switching tube Q1 is realized.

It should be noted that, as an equivalent alternative to this embodiment, the resistor R1 may also be connected to the anode of the OPT diode in the optical coupler.

The above are merely preferred embodiments of the present invention, and those skilled in the art to which the present invention pertains may make variations and modifications of the above-described embodiments. Therefore, the present invention is not limited to the specific control modes disclosed and described above, and modifications and variations of the present invention are also intended to fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.