Double-coil control circuit of contactor

Abstract

The utility model discloses a double-coil control circuit of a contactor, which comprises a driving module and a control module, the driving module is connected between a starting coil and a power supply, the control module comprises a first voltage comparator and a first capacitor, the non-inverting input end of the first voltage comparator is connected with the power supply, and the non-inverting input end of the first voltage comparator is connected with the power supply. Reference voltage is input to the reverse input end of the first voltage comparator, and the output end of the first voltage comparator is connected to the driving module through the first capacitor. When the voltage of the non-inverting input end of the first voltage comparator rises along with the voltage of the power supply and exceeds the reference voltage, the output end of the first voltage comparator outputs a high level, and the driving module can be conducted through the first capacitor, so that the starting coil is connected with the power supply. According to the utility model, the contactor can be effectively prevented from being normally closed due to the fact that the first capacitor is charged in advance, and the contactor can be ensured to work normally when the voltage of the power supply is slowly increased and decreased.

Description

Technical Field

[0001] The utility model relates to the technical field of contactors, in particular to a double-coil control circuit of a contactor. Background Art

[0002] In high-voltage DC contactors, they can be divided into single-coil and double-coil according to their structure. The double-coil of the contactor is the holding coil and the starting coil. Double-coil DC contactors generally have a built-in PCBA energy-saving board to cut off the starting coil after the relay is energized, leaving only the holding coil working, so as to achieve the purpose of reducing power consumption.

[0003] At present, in the market, the built-in energy-saving board of the double-coil contactor generally adopts an RC delay circuit. Its principle is to divide the voltage by resistance, and after reaching the opening voltage (Vgs(th)) of the MOS tube, the two coils of the contactor work at the same time. After the capacitor is fully charged, the branch where the capacitor is located is disconnected, the MOS tube is turned off, and the contactor is left with only the coil to work. According to the characteristics of the capacitor, as long as the external power supply starts to supply power, the capacitor will start to charge. If the external power supply voltage has not reached the working voltage of the contactor after the capacitor is fully charged, the contactor will not work properly, because the MOS tube cannot be turned on at this time, and the starting coil cannot work. Therefore, the double-coil contactor that generally adopts the RC delay circuit can only adopt pulse power supply. However, under some special working conditions, the external power supply voltage rises slowly, which may cause the capacitor to be fully charged, but the external power supply voltage has not reached the contactor working voltage, the MOS tube cannot be turned on, the starting coil cannot work, and then the contactor cannot work properly. Therefore, it is necessary to improve the prior art to overcome the defects in the prior art. Summary of the invention

[0004] The problem to be solved by the utility model is to provide a double-coil control circuit of a contactor, so as to overcome the defect that the control circuit of the existing contactor cannot be normally attracted when the voltage of the external power supply rises or falls slowly.

[0005] The utility model adopts the following technical scheme to solve the technical problem: a double-coil control circuit of a contactor, wherein the double coils are respectively a starting coil and a holding coil, and the holding coil is connected to a power supply; the control circuit comprises a driving module and a control module, wherein the driving module is connected between the starting coil and the power supply, and the control module comprises a first voltage comparator and a first capacitor, wherein the same-direction input end of the first voltage comparator is connected to the power supply, a reference voltage is input to the reverse input end of the first voltage comparator, and the output end of the first voltage comparator is connected to the driving module through the first capacitor; when the voltage at the same-direction input end of the first voltage comparator increases with the voltage of the power supply and exceeds the reference voltage, the output end of the first voltage comparator outputs a high level, and the driving module can be turned on through the first capacitor, thereby connecting the starting coil to the power supply; when the first capacitor is fully charged, an open circuit is formed between the first voltage comparator and the driving module, thereby disconnecting the starting coil from the power supply through the driving module.

[0006] As a further improvement of the present utility model, the control module also includes a second voltage comparator, the second voltage comparator is connected to the driving module, the first capacitor is connected between the first voltage comparator and the second voltage comparator, and the first voltage comparator, the first capacitor and the second voltage comparator are used to collaboratively control the on and off of the driving module.

[0007] As a further improvement of the present invention, the same-direction input terminal of the second voltage comparator is connected to the first capacitor, the reverse input terminal of the second voltage comparator is connected to the power supply through a second voltage divider resistor, and the output terminal of the second voltage comparator is connected to the driving module.

[0008] As a further improvement of the present invention, the driving module includes a MOS tube, the drain of the MOS tube is connected to the starting coil, the gate of the MOS tube is connected to the output end of the second voltage comparator, and the source of the MOS tube is grounded.

[0009] As a further improvement of the utility model, the driving module also includes a first Schottky diode connected between the starting coil and the drain of the MOS tube, a TVS tube connected between the drain and source of the MOS tube, and a first resistor and a first voltage regulator tube connected in parallel between the gate and source of the MOS tube.

[0010] As a further improvement of the present invention, the reverse input terminal of the first voltage comparator is connected to the positive electrode of the power supply through a sixteenth resistor, and the reverse input terminal of the first voltage comparator is also grounded through a third Zener diode, and the third Zener diode is used to control the reverse input terminal voltage of the first voltage comparator to the reference voltage.

[0011] As a further improvement of the present invention, the non-inverting input terminal of the first voltage comparator is connected to the power supply through a first voltage-dividing resistor.

[0012] As a further improvement of the present utility model, the dual-coil control circuit of the contactor also includes a wiring terminal, the wiring terminal is provided with a VCC terminal, a GND terminal, an HC terminal, a TC terminal and a COM terminal, the positive and negative electrodes of the power supply are respectively connected to the VCC terminal and the GND terminal, the VCC terminal is connected to the COM terminal, the holding coil is connected to the HC terminal and the COM terminal, the HC terminal is connected to the GND terminal, the starting coil is connected to the TC terminal and the COM terminal, and the TC terminal is connected to the drive module.

[0013] As a further improvement of the present invention, the first voltage comparator and the second voltage comparator are integrated on a dual voltage comparator chip of model LM2903B.

[0014] As a further improvement of the utility model, the VCC end is connected to the VCC positive electrode of the dual voltage comparator chip via a second Schottky diode, an inductor and a third resistor in sequence, the VCC negative electrode of the dual voltage comparator chip is grounded, and a second voltage regulator diode and a second capacitor are connected in parallel between the VCC positive electrode and the VCC negative electrode of the dual voltage comparator chip.

[0015] The beneficial effect of the utility model is as follows: the utility model provides a dual-coil control circuit of a contactor, which fixes the inverting input terminal voltage of the first voltage comparator at a reference voltage. When the power supply voltage of the contactor gradually rises to make the non-inverting input terminal voltage of the first voltage comparator exceed the set inverting input terminal voltage, i.e., the reference voltage, a high level will be output to charge the first capacitor, thereby connecting the starting coil to the power supply, avoiding charging the first capacitor in advance, which causes the contactor to fail to close normally, and can ensure that the contactor can work normally when the power supply voltage rises or falls slowly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a circuit schematic diagram of a double-coil control circuit of a contactor of the utility model;

[0017] Figure 2 This is a circuit schematic diagram of the double coil and drive module in the utility model;

[0018] Figure 3 This is a circuit schematic diagram of the control module in the utility model.

[0019] Combined with the accompanying drawings, the following description is given:

[0020] U1A, second voltage comparator; U1B, first voltage comparator; Q1, MOS tube; C1, first capacitor; C2, second capacitor; C3, third capacitor; D1, first Schottky diode; D2, second Schottky diode; D3, diode; ZD1, first voltage regulator; ZD2, second voltage regulator; ZD3, third voltage regulator; L1, inductor; L2, holding coil; L3, starting coil; J1, terminal; TVS1, TVS tube; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; R8, eighth resistor; R9, ninth resistor; R10, tenth resistor; R11, eleventh resistor; R12, twelfth resistor; R13, thirteenth resistor; R14, fourteenth resistor; R15, fifteenth resistor; R16, sixteenth resistor. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0022] See also Figures 1 to 3 The utility model provides a double-coil control circuit of a contactor, wherein the double coils are a starting coil L3 and a holding coil L2, and the two ends of the holding coil L2 are directly connected to the positive and negative poles of an external power supply, that is, as long as the external power supply starts to supply power, the holding coil L2 can be powered on and work immediately. One end of the starting coil L3 is connected to the positive pole of the power supply, and the other end of the starting coil L3 is connected to the negative pole of the power supply through the control circuit; wherein the negative pole of the power supply is grounded.

[0023] Specifically, the control circuit is provided with a wiring terminal J1, and the wiring terminal J1 is provided with a VCC terminal, a GND terminal, a HC terminal, a TC terminal and a COM terminal. The positive and negative electrodes of the power supply are respectively connected to the VCC terminal and the GND terminal, the VCC terminal is connected to the COM terminal, and the GND terminal is grounded; the two ends of the holding coil L2 are connected to the HC terminal and the COM terminal, and the HC terminal is connected to the GND terminal; the two ends of the starting coil L3 are connected to the TC terminal and the COM terminal, and the TC terminal is connected to the control circuit.

[0024] Furthermore, the control circuit includes a driving module and a control module, wherein the driving module is connected between the other end (or TC end) of the starting coil L3 and the negative electrode (or ground) of the power supply. The control module includes a first voltage comparator U1B and a first capacitor C1, wherein the same-direction input end of the first voltage comparator U1B is connected to the power supply through a first voltage-dividing resistor, a reference voltage is input to the reverse input end of the first voltage comparator U1B, and the output end of the first voltage comparator U1B is connected to the driving module through the first capacitor C1.

[0025] When the power supply voltage of the contactor gradually rises, the voltage of the same-direction input terminal of the first voltage comparator U1B increases with the voltage of the power supply and exceeds the reference voltage, and the output terminal of the first voltage comparator U1B outputs a high level to charge the first capacitor C1, and the drive module is turned on through the first capacitor C1, and then the start coil L3 is connected to the power supply. When the first capacitor C1 is fully charged, a short circuit is formed between the first voltage comparator U1B and the drive module, the drive module is turned off, and then the start coil L3 is disconnected from the power supply through the drive module.

[0026] It can be seen that the utility model fixes the inverting input voltage of the first voltage comparator U1B to the reference voltage. When the power supply voltage of the contactor gradually rises to make the non-inverting input voltage of the first voltage comparator U1B exceed the set inverting input voltage, i.e., the reference voltage, a high level will be output to charge the first capacitor C1, thereby connecting the starting coil L3 to the power supply, avoiding charging the first capacitor C1 in advance, which would cause the contactor to fail to close normally, and ensuring that the contactor can work normally when the power supply voltage rises or falls slowly.

[0027] See also Figure 2 The driving module includes a MOS tube Q1, which can be an NMOS tube. The drain of the MOS tube Q1 is connected to the start coil L3, the gate of the MOS tube Q1 is connected to the control module, and the source of the MOS tube Q1 is grounded. When the control module outputs a high level to the gate of the MOS tube Q1, the MOS tube Q1 is in a conducting state, thereby connecting the start coil L3 to the power supply; when the control module outputs a low level to the gate of the MOS tube Q1, the MOS tube Q1 is in a cut-off state, thereby disconnecting the start coil L3 from the power supply.

[0028] The driving module further includes a first Schottky diode D1, a TVS tube TVS1 (TVS1 is the label of the TVS tube), a first resistor R1 and a first voltage regulator ZD1. The first Schottky diode D1 is connected between the other end (or TC end) of the starting coil L3 and the drain of the MOS tube Q1 to suppress reverse voltage. The TVS tube TVS1 is connected between the drain and source of the MOS tube Q1 to protect the drain and source of the MOS tube Q1. The first resistor R1 and the first voltage regulator ZD1 are connected in parallel between the gate and source of the MOS tube Q1 to protect the gate of the MOS tube Q1.

[0029] In addition, if Figure 3 As shown, the control module also includes a second voltage comparator U1A, which is connected to the driving module, and the first capacitor C1 is connected between the first voltage comparator U1B and the second voltage comparator U1A. The first voltage comparator U1B, the first capacitor C1 and the second voltage comparator U1A are used to collaboratively control the on and off of the driving module.

[0030] Specifically, the non-inverting input terminal of the second voltage comparator U1A is connected to the first capacitor C1 through the eighth resistor R8, wherein the branch between the eighth resistor R8 and the first capacitor C1 is grounded through the tenth resistor R10 and the ninth resistor R9, and the ninth resistor R9 is connected in parallel with a diode D3. The reverse input terminal of the second voltage comparator U1A is connected to the power supply through the second voltage-dividing resistor, and the output terminal of the second voltage comparator U1A is connected to the gate of the MOS tube Q1 through the second resistor R2.

[0031] The voltage at the non-inverting input terminal of the first voltage comparator U1B will change with the change of the power supply voltage. As the power supply voltage increases, the voltage at the non-inverting input terminal of the first voltage comparator U1B will also increase. When the voltage at the non-inverting input terminal of the first voltage comparator U1B is greater than the voltage at its inverting input terminal, the output terminal of the first voltage comparator U1B will output a high level to the first capacitor C1, and then to the non-inverting input terminal of the second voltage comparator U1A through the first capacitor C1. At this time, the high level output by the first voltage comparator U1B is similar to the power supply voltage, and the first capacitor C1 starts to charge. Since the high level output by the first voltage comparator U1B is similar to the power supply voltage, the voltage at the non-inverting input terminal of the second voltage comparator U1A will be greater than the voltage at its inverting input terminal. The output terminal of the second voltage comparator U1A outputs a high level to the gate of the MOS tube Q1, controls the MOS tube Q1 to be turned on, and the starter coil L3 starts to work. The utility model can prevent the contactor from working unstably when the power supply voltage fluctuates greatly by using two voltage comparators, namely the first voltage comparator U1B and the second voltage comparator U1A, thus playing a double insurance role.

[0032] Optionally, the first voltage comparator U1B and the second voltage comparator U1A are integrated on a dual voltage comparator chip of model LM2903B. Figure 1 The middle number U1C represents the VCC positive electrode and VCC negative electrode of the dual voltage comparator chip. The positive electrode of the power supply (or the VCC end of the terminal J1) is connected to the VCC positive electrode of the dual voltage comparator chip via the second Schottky diode D2, the inductor L1 and the third resistor R3, which is used to power the dual voltage comparator chip; the VCC negative electrode of the dual voltage comparator chip is grounded, and the second voltage regulator ZD2 and the second capacitor C2 are connected in parallel between the VCC positive electrode and the VCC negative electrode of the dual voltage comparator chip.

[0033] See also Figure 3 The reverse input terminal of the first voltage comparator U1B is connected to the positive pole of VCC of the dual voltage comparator chip through the sixteenth resistor R16, and the reverse input terminal of the first voltage comparator U1B is also grounded through the third voltage regulator ZD3. The third voltage regulator ZD3 is used to control the reverse input terminal voltage of the first voltage comparator U1B to be a reference voltage.

[0034] Among them, the non-inverting input terminal of the first voltage comparator U1B is connected to the positive pole of VCC of the dual voltage comparator chip through the first voltage-dividing resistor. In this embodiment, specifically, the first voltage-dividing resistor includes a thirteenth resistor R13, a fourteenth resistor R14 and a fifteenth resistor R15, and the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15 are sequentially connected in series between the positive pole of VCC of the dual voltage comparator chip and the ground, and the non-inverting input terminal of the first voltage comparator U1B is connected between the fourteenth resistor R14 and the fifteenth resistor R15. In addition, a twelfth resistor R12 is connected between the non-inverting input terminal of the first voltage comparator U1B and its output terminal, an eleventh resistor R11 is connected between the output terminal of the first voltage comparator U1B and the positive pole of VCC of the dual voltage comparator chip, and a third capacitor C3 is connected between the non-inverting input terminal of the first voltage comparator U1B and the ground.

[0035] Continue reading Figure 3 The second voltage-dividing resistor connected to the reverse input terminal of the second voltage comparator U1A specifically includes a sixth resistor R6 and a seventh resistor R7, which are connected in series between the positive pole of VCC of the dual voltage comparator chip and the ground, and the reverse input terminal of the second voltage comparator U1A is connected between the sixth resistor R6 and the seventh resistor R7. In addition, a fifth resistor R5 is connected between the in-phase input terminal and the output terminal of the second voltage comparator U1A, and a fourth resistor R4 is connected between the output terminal of the second voltage comparator U1A and the positive pole of VCC of the dual voltage comparator chip.

[0036] In summary, the dual-coil control circuit of the contactor of the utility model fixes the inverting input voltage of the first voltage comparator U1B to the reference voltage. When the power supply voltage of the contactor gradually increases and the non-inverting input voltage of the first voltage comparator U1B exceeds the set inverting input voltage, i.e., the reference voltage, a high level will be output to charge the first capacitor C1, thereby connecting the starting coil L3 to the power supply, avoiding charging the first capacitor C1 in advance, which would cause the contactor to fail to close normally, and ensuring that the contactor can work normally when the power supply voltage rises or falls slowly.

[0037] In the above description, many specific details are described to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited by the specific implementation disclosed above. At the same time, any person familiar with the technical field can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A dual-coil control circuit for a contactor, wherein the dual coils are a starting coil (L3) and a holding coil (L2), and the holding coil (L2) is connected to a power supply; characterized in that: The control circuit comprises a driving module and a control module, wherein the driving module is connected between the starting coil (L3) and the power supply, and the control module comprises a first voltage comparator (U1B) and a first capacitor (C1), wherein the same-direction input terminal of the first voltage comparator (U1B) is connected to the power supply, the reverse input terminal of the first voltage comparator (U1B) is input with a reference voltage, and the output terminal of the first voltage comparator (U1B) is connected to the driving module through the first capacitor (C1); when the voltage at the same-direction input terminal of the first voltage comparator (U1B) increases with the voltage of the power supply and exceeds the reference voltage, the output terminal of the first voltage comparator (U1B) outputs a high level, and the driving module can be turned on through the first capacitor (C1), thereby connecting the starting coil (L3) to the power supply; when the first capacitor (C1) is fully charged, an open circuit is formed between the first voltage comparator (U1B) and the driving module, thereby disconnecting the starting coil (L3) from the power supply through the driving module.

2. The double-coil control circuit of the contactor according to claim 1, characterized in that: The control module also includes a second voltage comparator (U1A), the second voltage comparator (U1A) is connected to the driving module, the first capacitor (C1) is connected between the first voltage comparator (U1B) and the second voltage comparator (U1A), and the first voltage comparator (U1B), the first capacitor (C1) and the second voltage comparator (U1A) are used to collaboratively control the on and off of the driving module.

3. The double-coil control circuit of the contactor according to claim 2, characterized in that: The same-direction input terminal of the second voltage comparator (U1A) is connected to the first capacitor (C1), the reverse input terminal of the second voltage comparator (U1A) is connected to the power supply via a second voltage-dividing resistor, and the output terminal of the second voltage comparator (U1A) is connected to the driving module.

4. The double-coil control circuit of the contactor according to claim 3, characterized in that: The driving module comprises a MOS tube (Q1), a drain of the MOS tube (Q1) is connected to the starting coil (L3), a gate of the MOS tube (Q1) is connected to the output end of the second voltage comparator (U1A), and a source of the MOS tube (Q1) is grounded.

5. The double-coil control circuit of the contactor according to claim 4, characterized in that: The driving module further comprises a first Schottky diode (D1) connected between the starting coil (L3) and the drain of the MOS tube (Q1), a TVS tube (TVS1) connected between the drain and source of the MOS tube (Q1), and a first resistor (R1) and a first voltage regulator tube (ZD1) connected in parallel between the gate and source of the MOS tube (Q1).

6. The double-coil control circuit of the contactor according to claim 1, characterized in that: The reverse input terminal of the first voltage comparator (U1B) is connected to the positive electrode of the power supply through a sixteenth resistor (R16), and the reverse input terminal of the first voltage comparator (U1B) is also grounded through a third voltage regulator (ZD3), and the third voltage regulator (ZD3) is used to control the reverse input terminal voltage of the first voltage comparator (U1B) to be the reference voltage.

7. The double-coil control circuit of the contactor according to claim 1, characterized in that: The non-inverting input terminal of the first voltage comparator (U1B) is connected to the power supply through a first voltage dividing resistor.

8. The double-coil control circuit of the contactor according to claim 2, characterized in that: It also includes a wiring terminal (J1), wherein the wiring terminal (J1) is provided with a VCC terminal, a GND terminal, an HC terminal, a TC terminal and a COM terminal, the positive electrode and the negative electrode of the power supply are respectively connected to the VCC terminal and the GND terminal, the VCC terminal is connected to the COM terminal, the holding coil (L2) is connected to the HC terminal and the COM terminal, the HC terminal is connected to the GND terminal, the starting coil (L3) is connected to the TC terminal and the COM terminal, and the TC terminal is connected to the driving module.

9. The double-coil control circuit of the contactor according to claim 8, characterized in that: The first voltage comparator (U1B) and the second voltage comparator (U1A) are integrated on a dual voltage comparator chip of model LM2903B.

10. The double-coil control circuit of the contactor according to claim 9, characterized in that: The VCC end is connected to the VCC positive electrode of the dual voltage comparator chip via a second Schottky diode (D2), an inductor (L1) and a third resistor (R3) in sequence; the VCC negative electrode of the dual voltage comparator chip is grounded; and a second voltage regulator (ZD2) and a second capacitor (C2) are connected in parallel between the VCC positive electrode and the VCC negative electrode of the dual voltage comparator chip.

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