Control circuit of double-coil contactor

Abstract

The utility model provides a control circuit of a double-coil contactor. The control circuit of the double-coil contactor comprises a power supply circuit, a bistable circuit, a driving circuit, an electronic switch and a starting time-delay circuit, the input end of the power supply circuit is electrically connected with a power supply, the output end of the power supply circuit is electrically connected with the input end of the bistable circuit, the output end of the bistable circuit is electrically connected with the input end of the driving circuit, and the output end of the driving circuit is electrically connected with the control end of the electronic switch. The input end of the electronic switch is electrically connected with a starting coil in the double-coil contactor, and the output end of the electronic switch is grounded; the start delay circuit is used for sending a trigger signal to the bistable circuit after the electronic switch is turned on for a preset time length; the bistable circuit is used for changing the working state of the bistable circuit according to the trigger signal so as to close the driving circuit and keep the driving circuit. Compared with a mode of adopting a mechanical switch, the double-coil contactor has the advantages that the condition of generating electric arc is avoided, the condition of dust entering is also avoided, and the control reliability of the double-coil contactor is improved.

Description

Technical Field

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

[0002] The dual-coil contactor includes a holding coil and a starting coil. The holding coil is usually continuously powered on after the power is supplied, but the magnetic attraction of the holding coil can only maintain the pull-in, and cannot achieve the process from disconnection to pull-in; while the starting coil can achieve the process from disconnection to pull-in. In order to achieve pull-in more reliably, the holding coil is powered on first, and then the start-up pull-in is completed by powering on the starting coil. After the start-up pull-in is completed, the power on of the starting coil is disconnected, and the power on of the holding coil is used to maintain the pull-in, so as to reduce the current in the pull-in state.

[0003] In the prior art, a mechanical switch is usually used to power on and off the starter coil. However, when the mechanical switch is disconnected, an arc is generated, which shortens the life of the entire device. In addition, the mechanical switch cannot be completely sealed, and dust may enter, thereby affecting its performance. Based on the above two points, the use of a mechanical switch in the prior art will result in poor control reliability of the dual-coil contactor. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a control circuit for a double-coil contactor.

[0005] In one embodiment, the utility model provides a control circuit of a dual-coil contactor, the control circuit of the dual-coil contactor comprising:

[0006] Power supply circuit, bistable circuit, drive circuit, electronic switch and start-up delay circuit;

[0007] The input end of the power supply circuit is electrically connected to the power supply, the output end of the power supply circuit is electrically connected to the input end of the bistable circuit, the output end of the bistable circuit is electrically connected to the input end of the drive circuit, the output end of the drive circuit is electrically connected to the control end of the electronic switch, the input end of the electronic switch is electrically connected to the starting coil in the double-coil contactor, the output end of the electronic switch is grounded, the input end of the start delay circuit is electrically connected to the output end of the drive circuit, and the output end of the start delay circuit is electrically connected to the control end of the bistable circuit;

[0008] The start-up delay circuit is used to send a trigger signal to the bistable circuit after the electronic switch is turned on for a preset time; the bistable circuit is used to change its own working state according to the trigger signal to turn off the drive circuit and maintain it.

[0009] In one embodiment, the bistable circuit includes a first pnp transistor, a first npn transistor, a first capacitor, a first voltage drop resistor, and a second voltage drop resistor;

[0010] The emitter of the first pnp type transistor is electrically connected to the first end of the first voltage drop resistor, the output end of the power supply circuit and the first end of the first capacitor respectively, the base of the first pnp type transistor is electrically connected to the second end of the first voltage drop resistor, the collector of the first npn type transistor and the input end of the drive circuit respectively, the collector of the first pnp type transistor is electrically connected to the base of the first npn type transistor, the second end of the first capacitor, the first end of the second voltage drop resistor and the output end of the start-up delay circuit respectively, and the emitter of the first npn type transistor and the second end of the second voltage drop resistor are grounded respectively.

[0011] In one embodiment, the driving circuit includes a second pnp transistor and a third voltage drop resistor;

[0012] The emitter of the second pnp type transistor is electrically connected to the output end of the power supply circuit and the first end of the third voltage drop resistor respectively, the base of the second pnp type transistor is electrically connected to the second end of the third voltage drop resistor and the collector of the first npn type transistor respectively, and the collector of the second pnp type transistor is electrically connected to the control end of the electronic switch and the input end of the start delay circuit respectively.

[0013] In one embodiment, the startup delay circuit includes a second capacitor, a second npn-type transistor, a fourth voltage drop resistor and a charging circuit;

[0014] The first end of the second capacitor is electrically connected to the base of the second npn-type transistor, the output end of the charging circuit and the first end of the fourth voltage drop resistor respectively, the second end of the second capacitor, the emitter of the second npn-type transistor and the second end of the fourth voltage drop resistor are grounded respectively, the collector of the second npn-type transistor is electrically connected to the base of the first npn-type transistor, and the input end of the charging circuit is electrically connected to the output end of the driving circuit.

[0015] In one embodiment, the charging circuit includes a first zener diode;

[0016] The anode of the first voltage-stabilizing diode is electrically connected to the base of the second npn-type transistor, the first end of the fourth voltage-dropping resistor and the first end of the second capacitor respectively, and the cathode of the first voltage-stabilizing diode is electrically connected to the output end of the driving circuit.

[0017] In one embodiment, the input end of the charging circuit is electrically connected to the output end of the driving circuit through an electronic switch, and the charging circuit includes a third pnp transistor and a fifth voltage drop resistor;

[0018] The emitter of the third pnp type transistor is electrically connected to the output end of the power supply circuit and the first end of the fifth voltage drop resistor respectively, the base of the third pnp type transistor is electrically connected to the second end of the fifth voltage drop resistor and the input end of the electronic switch respectively, and the collector of the third pnp type transistor is electrically connected to the base of the second npn type transistor, the first end of the fourth voltage drop resistor, and the first end of the second capacitor respectively.

[0019] In one embodiment, the input end of the charging circuit is electrically connected to the output end of the driving circuit through an electronic switch, and the charging circuit includes a first voltage-stabilizing diode and a sixth voltage-dropping resistor;

[0020] A first end of the sixth voltage drop resistor is electrically connected to the output end of the electronic switch and the cathode of the first voltage stabilizing diode respectively, and a second end of the sixth voltage drop resistor is grounded.

[0021] In one embodiment, the control circuit of the dual-coil contactor further includes a voltage trigger circuit;

[0022] The input end of the voltage trigger circuit is electrically connected to the output end of the power supply circuit, and the output end of the voltage trigger circuit is electrically connected to the input end of the bistable circuit;

[0023] The voltage trigger circuit is used to output a voltage to the bistable circuit when the input voltage is greater than a preset voltage value.

[0024] In one embodiment, the voltage trigger circuit includes a second voltage stabilizing diode, a fourth pnp transistor, a third npn transistor, a seventh voltage drop resistor, and an eighth voltage drop resistor;

[0025] The cathode of the second voltage-regulating diode is electrically connected to the output end of the power supply circuit, the first end of the seventh voltage-drop resistor and the emitter of the fourth pnp type transistor, respectively; the anode of the second voltage-regulating diode is electrically connected to the base of the third npn type transistor and the first end of the eighth voltage-drop resistor, respectively; the base of the fourth pnp type transistor is electrically connected to the second end of the seventh voltage-drop resistor and the collector of the third npn type transistor, respectively; the collector of the fourth pnp type transistor is electrically connected to the input end of the bistable circuit, and the emitter of the third npn type transistor and the second end of the eighth voltage-drop resistor are grounded, respectively.

[0026] In one embodiment, the power supply circuit includes a surge protection circuit, a rectification circuit and a linear voltage stabilization circuit;

[0027] The input end of the surge protection circuit is electrically connected to the power supply, the output end of the surge protection circuit is electrically connected to the input end of the rectifier circuit, the output end of the rectifier circuit is electrically connected to the input end of the linear voltage stabilization circuit and the power supply end of the double-coil contactor respectively, and the output end of the linear voltage stabilization circuit is electrically connected to the input end of the bistable circuit.

[0028] Through the control circuit of the dual-coil contactor, an electronic switch is set to control the power on and off of the start coil, and a start delay circuit and a bistable circuit are set to control the power off of the start coil when the preset time is reached after power on, and finally the pull-in process of the dual-coil contactor is fully realized. Compared with the method of using a mechanical switch, there is no arc generation and no dust entry, which improves the control reliability of the dual-coil contactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a schematic diagram of the structure of a control circuit of a double-coil contactor in one embodiment of the utility model;

[0031] Figure 2 A schematic diagram of the specific structure of a bistable circuit and a start-up delay circuit in one embodiment of the utility model;

[0032] Figure 3 This is a schematic diagram of the specific structure of the start-up delay circuit in another embodiment of the utility model;

[0033] Figure 4 It is a structural schematic diagram of a control circuit of a double-coil contactor including a voltage trigger circuit in one embodiment of the utility model;

[0034] Figure 5 A schematic diagram of the specific structure of a voltage trigger circuit in one embodiment of the utility model;

[0035] Figure 6 The figure is a schematic diagram of the specific structure of the power supply circuit in one embodiment of the utility model. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0037] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In the present application, the word "exemplary" is used to mean "used as an example, illustration or description". Any embodiment described as "exemplary" in the present application is not necessarily interpreted as being more preferred or more advantageous than other embodiments. In order to enable any person skilled in the art to implement and use the utility model, the following description is given. In the following description, details are listed for the purpose of explanation. It should be understood that one of ordinary skill in the art can recognize that the utility model can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid unnecessary details that make the description of the utility model obscure. Therefore, the utility model is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in this application.

[0038] like Figure 1 As shown, in one embodiment, the utility model provides a control circuit of a dual-coil contactor, and the control circuit of the dual-coil contactor includes a power supply circuit, a bistable circuit, a drive circuit, an electronic switch and a start-up delay circuit.

[0039] The input end of the power supply circuit is electrically connected to the power supply, the output end of the power supply circuit is electrically connected to the input end of the bistable circuit, the output end of the bistable circuit is electrically connected to the input end of the drive circuit, the output end of the drive circuit is electrically connected to the control end of the electronic switch, the input end of the electronic switch is electrically connected to the starting coil in the double-coil contactor, the output end of the electronic switch is grounded, the input end of the start delay circuit is electrically connected to the output end of the drive circuit, and the output end of the start delay circuit is electrically connected to the control end of the bistable circuit.

[0040] Among them, when the power supply circuit is a DC-DC circuit, the power supply connected to its input end is a DC power supply, and when the power supply circuit is an AC-DC circuit, the power supply connected to its input end is an AC power supply. The specific type of the power supply circuit can be configured according to the actual power supply type.

[0041] Among them, Figure 1 In the embodiment, the output end of the power supply circuit is electrically connected to the input end of the bistable circuit as well as to the power supply end of the drive circuit. This is because the power supply circuit has losses after passing through the bistable circuit, which may make the drive circuit unable to output sufficient drive signals to the electronic switch, thereby reducing the reliability of the drive. When the output end of the power supply circuit is directly electrically connected to the power supply end of the drive circuit, the power supply circuit can provide a lossless voltage to the drive circuit, so that it can output sufficient drive signals to the electronic switch.

[0042] The start-up delay circuit is used to send a trigger signal to the bistable circuit after the electronic switch is turned on for a preset time; the bistable circuit is used to change its own working state according to the trigger signal to turn off the drive circuit and maintain it.

[0043] Among them, when the power supply circuit outputs normally, the working state of the bistable circuit is the first state, thereby sending a first signal to the drive circuit, so that the drive circuit sends a drive signal to the electronic switch; similarly, when the power supply circuit does not output normally, the working state of the bistable circuit is the second state, thereby sending a second signal to the drive circuit, so that the drive circuit cannot send a drive signal to the electronic switch.

[0044] Among them, since it is necessary to power off the starting coil after it is powered on for a period of time when controlling the dual-coil contactor, so as to ensure that the current of the dual-coil contactor in the attracted state is small. To this end, in the present embodiment, a starting delay circuit is provided, and the starting delay circuit can delay at the same time when the driving circuit drives the electronic switch to turn on, and send a trigger signal to the bistable circuit after the delay reaches a preset time length. The trigger signal changes the working state of the bistable circuit from the first state to the second state, thereby sending a second signal to the driving circuit, so that the driving circuit cannot send a driving signal to the electronic switch, so that the electronic switch is cut off, and then the starting coil of the dual-coil contactor is powered off. It should be noted that the bistable circuit has a self-locking function, and after it switches to the second state, it will keep the state from changing, so as to avoid repeated power-on of the starting coil of the dual-coil contactor.

[0045] Through the control circuit of the dual-coil contactor, an electronic switch is set to control the power on and off of the start coil, and a start delay circuit and a bistable circuit are set to control the power off of the start coil when the preset time is reached after power on, and finally the pull-in process of the dual-coil contactor is fully realized. Compared with the method of using a mechanical switch, there is no arc generation and no dust entry, which improves the control reliability of the dual-coil contactor.

[0046] like Figure 2 As shown, in one embodiment, the bistable circuit includes a first pnp transistor Q3, a first npn transistor Q6, a first capacitor C1, a first voltage drop resistor R3 and a second voltage drop resistor R14.

[0047] The emitter of the first pnp transistor Q3 is electrically connected to the first end of the first voltage drop resistor R3, the output end of the power supply circuit and the first end of the first capacitor C1, and the base of the first pnp transistor Q3 is electrically connected to the second end of the first voltage drop resistor R3, the collector of the first npn transistor Q6 and the input end of the drive circuit (such as Figure 2 The collector of the first pnp transistor Q3 is electrically connected to the base of the first npn transistor Q6, the second end of the first capacitor C1, the first end of the second voltage drop resistor R14 and the output end of the start delay circuit (such as Figure 2 The collector of the second npn-type transistor Q8 in the circuit is electrically connected, and the emitter of the first npn-type transistor Q6 and the second end of the second voltage drop resistor R14 are grounded respectively.

[0048] Among them, when the power supply circuit outputs normally, the first capacitor C1 is charged, and the voltage at the second end of the first capacitor C1 is pulled up by utilizing the characteristic that the voltage at both ends of the capacitor cannot change suddenly, so that the base of the first npn-type transistor Q6 is at a high level. Due to the existence of the second voltage drop resistor R14, there is a voltage drop between the base and the emitter of the first npn-type transistor Q6, which meets its conduction condition, and the first npn-type transistor Q6 is turned on. When the first npn-type transistor Q6 is turned on, the voltage of the base of the first pnp-type transistor Q3 is pulled down. Due to the existence of the first voltage drop resistor R3, there is a voltage drop between the emitter and the base of the first pnp-type transistor Q3, which meets its conduction condition, and the first pnp-type transistor Q3 is turned on. When the first pnp transistor Q3 is turned on, under the action of the second voltage drop resistor R14, the current passing through the first pnp transistor Q3 continuously pulls up the voltage of the base of the first npn transistor Q6 (it should be noted that it is not possible to continuously pull up the voltage of the base of the first npn transistor Q6 only by charging the first capacitor C1, because the second end of the first capacitor C1 is grounded, and its voltage will gradually decrease to the ground voltage after being pulled up), so that the first npn transistor Q6 is continuously turned on. In the process of the first npn transistor Q6 being continuously turned on, the collector of the first npn transistor Q6 is electrically connected to the input end of the drive circuit, thereby continuously sending a low-level first signal to the input end of the drive circuit, so that the drive circuit sends a drive signal to the electronic switch according to the low-level first signal.

[0049] Among them, when the start-up delay circuit (such as the collector of the second npn-type transistor Q8) sends a low-level trigger signal to the base of the first npn-type transistor Q6 after a preset time length, the voltage of the base of the first npn-type transistor Q6 is pulled down, the first npn-type transistor Q6 is turned off, the voltage of the base of the first pnp-type transistor Q3 is pulled up, and the first pnp-type transistor Q3 is turned off. Since the first capacitor C1 has been charged, although the power supply circuit is still outputting normally, it can no longer increase the voltage of the base of the first npn-type transistor Q6 through the characteristic that the voltage at both ends cannot change suddenly, so that the collector of the first npn-type transistor Q6 continues to send a high-level second signal to the drive circuit (such as the base of the second pnp-type transistor Q2), so that the drive circuit can no longer send a drive signal to the electronic switch, and the starting coil of the dual-coil contactor is powered off, thereby completing the entire attraction process.

[0050] like Figure 2 As shown, in one embodiment, the driving circuit includes a second pnp transistor Q2 and a third voltage drop resistor R4.

[0051] Among them, the emitter of the second pnp transistor Q2 is electrically connected to the output end of the power supply circuit to access the voltage VCC, and is also electrically connected to the first end of the third voltage drop resistor R4. The base of the second pnp transistor Q2 is electrically connected to the second end of the third voltage drop resistor R4 and the collector of the first npn transistor Q6 (for example, electrically connected to the collector of the first npn transistor Q6 through a series resistor R9 and a diode D3). The collector of the second pnp transistor Q2 is electrically connected to the control end of the electronic switch and the input end of the start delay circuit to output a drive signal Driver.

[0052] Among them, when the collector of the first npn-type transistor Q6 sends a low-level first signal to the base of the second pnp-type transistor Q2, the voltage of the base of the second pnp-type transistor Q2 is pulled down, and under the action of the third voltage drop resistor R4, a voltage drop is generated between the emitter and the base of the second pnp-type transistor Q2, which satisfies its conduction condition, and the second pnp-type transistor Q2 is turned on, and the connected voltage VCC is output through the second pnp-type transistor Q2 to obtain the driving signal Rriver. Similarly, when the collector of the first npn-type transistor Q6 sends a high-level second signal to the base of the second pnp-type transistor Q2, the voltage of the base of the second pnp-type transistor Q2 is pulled up, the second pnp-type transistor Q2 is turned off, and the connected voltage VCC cannot be output, and thus the driving signal Driver cannot be obtained.

[0053] like Figure 2 As shown, in one embodiment, the start-up delay circuit includes a second capacitor C4, a second npn transistor Q8, a fourth voltage drop resistor R16 and a charging circuit (in Figure 2 In the embodiment, the charging circuit may include a first voltage stabilizing diode D8).

[0054] Among them, the first end of the second capacitor C4 is electrically connected to the base of the second npn-type transistor Q8, the anode of the first voltage-dropping diode D8 and the first end of the fourth voltage-dropping resistor R16, respectively; the second end of the second capacitor C4, the emitter of the second npn-type transistor Q8 and the second end of the fourth voltage-dropping resistor R16 are grounded, respectively; the collector of the second npn-type transistor Q8 is electrically connected to the base of the first npn-type transistor Q6; and the cathode of the first voltage-dropping diode D8 is electrically connected to the output end of the driving circuit to access the driving signal Driver.

[0055] In this embodiment, the electronic switch may include a MOS tube Q7.

[0056] Among them, when the driving circuit outputs the driving signal Driver, the voltage of the gate of the MOS tube Q7 is pulled up, the MOS tube Q7 is turned on, and the starting coil of the dual-coil contactor K1 is powered on; at the same time, the first voltage stabilizing diode D8 is broken down, the second capacitor C4 is charged, and the voltage of the base of the second npn-type transistor Q8 continues to increase. When the voltage drop between the base and the emitter of the second npn-type transistor Q8 reaches the conduction condition, the second npn-type transistor Q8 is turned on, the voltage of the base of the first npn-type transistor Q6 is pulled down, and the voltage of the base of the second pnp-type transistor Q2 is pulled up, and the driving signal Driver cannot be obtained, the MOS tube Q7 is turned off, and the starting coil of the dual-coil contactor K1 is powered off. It can be seen that the time required for the charging process of the second capacitor C4 determines the power-on time of the start coil of the dual-coil contactor K1; specifically, the time required for the charging process is determined by the amplitude of the drive signal Driver, the resistance of the resistor R15, the resistance of the fourth voltage drop resistor R16, and the capacity of the second capacitor C4. Specifically, according to the formula t=RCLn{E / (E-Vt)}, t represents the charging time, E represents the remaining amplitude of the drive signal Driver after the voltage drop of the resistor R15, R represents the resistance of the resistor R16, C represents the capacity of the capacitor, Vt represents the voltage on the capacitor at any time, and Vt can be set to the conduction voltage of the second npn-type transistor Q8.

[0057] like Figure 2 As shown, in one embodiment, the input end of the charging circuit is electrically connected to the output end of the driving circuit through an electronic switch, and the charging circuit includes a third pnp transistor Q9 and a fifth voltage drop resistor R18.

[0058] Among them, the emitter of the third pnp type transistor Q9 is electrically connected to the output end of the power supply circuit to access the voltage VCC, and is also electrically connected to the first end of the fifth voltage drop resistor R18. The base of the third pnp type transistor Q9 is electrically connected to the second end of the fifth voltage drop resistor R18 and the input end of the electronic switch (such as the drain of the MOS tube Q7), and the collector of the third pnp type transistor Q9 is electrically connected to the base of the second npn type transistor Q8, the first end of the fourth voltage drop resistor R16 and the first end of the second capacitor C4.

[0059] In the above embodiment, it has been mentioned that the charging circuit may only include the first voltage stabilizing diode D8. Figure 2 In the circuit structure, two circuit structures are included at the same time. However, it should be noted that Figure 2 In the figure, the connection relationship of the first voltage stabilizing diode D8 is indicated by a dotted line, which indicates that the two modes are optional and are not used simultaneously.

[0060] Among them, when the driving circuit outputs the driving signal Driver, the MOS tube Q7 is turned on, the voltage of the base of the third pnp-type transistor Q9 is pulled down, and under the action of the fifth voltage drop resistor R18, the voltage drop between the emitter and the base of the third pnp-type transistor Q9 meets the conduction condition, the third pnp-type transistor Q9 is turned on, and the connected voltage VCC is charged to the second capacitor C4 through the third pnp-type transistor Q9. In this process, the time required for the charging process is determined by the voltage VCC, the resistance of the resistor R15, the resistance of the fourth voltage drop resistor R16, and the capacity of the second capacitor C4. The specific process of the charging time can refer to the above embodiment, the difference is that, in this embodiment, E represents the amplitude of VCC remaining after the voltage drop of the resistor R15.

[0061] like Figure 3 As shown, in one embodiment, the input end of the charging circuit is electrically connected to the output end of the driving circuit through an electronic switch, and the charging circuit includes a first voltage-stabilizing diode D8 and a sixth voltage-dropping resistor R20.

[0062] The first end of the sixth voltage drop resistor R20 is electrically connected to the output end of the electronic switch (the source of the MOS tube Q7) and the cathode of the first voltage stabilizing diode D8 respectively, and the second end of the sixth voltage drop resistor R20 is grounded.

[0063] Among them, when the MOS tube Q7 is turned on, the voltage of the cathode of the first voltage-regulating diode D8 is pulled up by the voltage-dividing effect of the sixth voltage-dropping resistor R20, so that the first voltage-regulating diode D8 is broken down, and then the second capacitor C4 is charged. The subsequent process and principle can refer to the above embodiment and will not be repeated here.

[0064] like Figure 4 As shown, in one embodiment, the control circuit of the dual-coil contactor further includes a voltage trigger circuit.

[0065] The input end of the voltage trigger circuit is electrically connected to the output end of the power supply circuit, and the output end of the voltage trigger circuit is electrically connected to the input end of the bistable circuit.

[0066] The voltage trigger circuit is used to output a voltage to the bistable circuit when the input voltage is greater than a preset voltage value.

[0067] The voltage trigger circuit can output voltage to the bistable circuit only when the voltage output by the power supply circuit is greater than the preset voltage value, so as to ensure that the electronic switch in the subsequent circuit is turned on when the voltage is high, thereby protecting the electronic switch. Specifically, taking the electronic switch as a MOS tube as an example, its turn-on voltage is usually 10V, and the voltage trigger circuit can prevent the MOS tube from being turned on when the voltage is near the Miller platform and causing damage.

[0068] like Figure 5As shown, in one embodiment, the voltage trigger circuit includes a second voltage stabilizing diode D2, a fourth pnp transistor Q1, a third npn transistor Q5, a seventh voltage drop resistor R2 and an eighth voltage drop resistor R12.

[0069] Among them, the cathode of the second voltage-stabilizing diode D2 is electrically connected to the output end of the power supply circuit to access the voltage VCC, and is also electrically connected to the first end of the seventh voltage-drop resistor R2 and the emitter of the fourth pnp-type transistor Q1. The anode of the second voltage-stabilizing diode D2 is electrically connected to the base of the third npn-type transistor Q5 and the first end of the eighth voltage-drop resistor R12, respectively. The base of the fourth pnp-type transistor Q1 is electrically connected to the second end of the seventh voltage-drop resistor R2 and the collector of the third npn-type transistor Q5, respectively. The collector of the fourth pnp-type transistor Q1 is electrically connected to the input end of the bistable circuit (such as the first end of the first voltage-drop resistor R3), and the emitter of the third npn-type transistor Q5 and the second end of the eighth voltage-drop resistor R12 are grounded, respectively.

[0070] Among them, when the connected voltage VCC exceeds the voltage stabilization value of the second voltage stabilizing diode D2, the second voltage stabilizing diode D2 is broken down, the voltage of the base of the third npn-type transistor Q5 is pulled up, and under the action of the eighth voltage drop resistor R12, the voltage drop between the base and the emitter of the third npn-type transistor Q5 meets its conduction condition, and the third npn-type transistor Q5 is turned on. When the third npn-type transistor Q5 is turned on, the voltage of the base of the fourth pnp-type transistor Q1 is pulled down, and under the action of the seventh voltage drop resistor R2, the voltage drop between the emitter and the base of the fourth pnp-type transistor Q1 meets its conduction condition, the fourth pnp-type transistor Q1 is turned on, and the connected voltage VCC can be output to the next stage.

[0071] Among them, Figure 5 As shown, the voltage trigger circuit further includes a resistor R10, and the resistor R10 serves as a dummy load to achieve rapid discharge.

[0072] In one embodiment, the power supply circuit includes a surge protection circuit, a rectification circuit and a linear voltage regulation circuit.

[0073] The input end of the surge protection circuit is electrically connected to the power supply, the output end of the surge protection circuit is electrically connected to the input end of the rectifier circuit, the output end of the rectifier circuit is electrically connected to the input end of the linear voltage stabilization circuit and the power supply end of the double-coil contactor respectively, and the output end of the linear voltage stabilization circuit is electrically connected to the input end of the bistable circuit.

[0074] Among them, Figure 6 As shown, the surge protection circuit includes a varistor RV1, the rectifier circuit includes a rectifier bridge D1, and the linear voltage stabilization circuit includes a third voltage stabilization diode D4 and a fourth npn-type transistor Q4. In addition, the power supply circuit also includes an input filter capacitor C2 and an output filter capacitor C3.

[0075] Among them, Figure 2 and Figure 6 As shown, the power circuit outputs voltage Power in addition to outputting voltage VCC. The function of voltage VCC can refer to the above embodiment and will not be described here. Voltage Power is used to output to the power supply terminal of the dual-coil contactor K1 as the power supply for the holding coil and the starting coil therein.

[0076] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0077] The control circuit of a dual-coil contactor provided by the utility model is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation method of the utility model. The description of the above embodiments is only used to help understand the method and core idea of ​​the utility model; at the same time, for technicians in this field, according to the idea of ​​the utility model, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the utility model.

[0078] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A control circuit for a double-coil contactor, characterized in that: The control circuit of the double-coil contactor comprises: Power supply circuit, bistable circuit, drive circuit, electronic switch and start-up delay circuit; The input end of the power supply circuit is electrically connected to the power supply, the output end of the power supply circuit is electrically connected to the input end of the bistable circuit, the output end of the bistable circuit is electrically connected to the input end of the drive circuit, the output end of the drive circuit is electrically connected to the control end of the electronic switch, the input end of the electronic switch is electrically connected to the starting coil in the double-coil contactor, the output end of the electronic switch is grounded, the input end of the start delay circuit is electrically connected to the output end of the drive circuit, and the output end of the start delay circuit is electrically connected to the control end of the bistable circuit; The start-up delay circuit is used to send a trigger signal to the bistable circuit after the electronic switch is turned on for a preset time; the bistable circuit is used to change its own working state according to the trigger signal to turn off the drive circuit and maintain it.

2. The control circuit of the double-coil contactor according to claim 1, characterized in that: The bistable circuit comprises a first pnp transistor, a first npn transistor, a first capacitor, a first voltage drop resistor and a second voltage drop resistor; The emitter of the first pnp type transistor is electrically connected to the first end of the first voltage drop resistor, the output end of the power supply circuit and the first end of the first capacitor respectively, the base of the first pnp type transistor is electrically connected to the second end of the first voltage drop resistor, the collector of the first npn type transistor and the input end of the drive circuit respectively, the collector of the first pnp type transistor is electrically connected to the base of the first npn type transistor, the second end of the first capacitor, the first end of the second voltage drop resistor and the output end of the start-up delay circuit respectively, and the emitter of the first npn type transistor and the second end of the second voltage drop resistor are grounded respectively.

3. The control circuit of the double-coil contactor according to claim 2, characterized in that: The driving circuit includes a second pnp type transistor and a third voltage drop resistor; The emitter of the second pnp type transistor is electrically connected to the output end of the power supply circuit and the first end of the third voltage drop resistor, respectively; the base of the second pnp type transistor is electrically connected to the second end of the third voltage drop resistor and the collector of the first npn type transistor, respectively; and the collector of the second pnp type transistor is electrically connected to the control end of the electronic switch and the input end of the start-up delay circuit, respectively.

4. The control circuit of the double-coil contactor according to claim 2, characterized in that: The startup delay circuit includes a second capacitor, a second npn-type transistor, a fourth voltage drop resistor and a charging circuit; The first end of the second capacitor is electrically connected to the base of the second npn-type transistor, the output end of the charging circuit and the first end of the fourth voltage drop resistor respectively, the second end of the second capacitor, the emitter of the second npn-type transistor and the second end of the fourth voltage drop resistor are grounded respectively, the collector of the second npn-type transistor is electrically connected to the base of the first npn-type transistor, and the input end of the charging circuit is electrically connected to the output end of the driving circuit.

5. The control circuit of the double-coil contactor according to claim 4, characterized in that: The charging circuit includes a first voltage stabilizing diode; The anode of the first voltage-stabilizing diode is electrically connected to the base of the second npn-type transistor, the first end of the fourth voltage-dropping resistor and the first end of the second capacitor respectively, and the cathode of the first voltage-stabilizing diode is electrically connected to the output end of the driving circuit.

6. The control circuit of the double-coil contactor according to claim 4, characterized in that: The input end of the charging circuit is electrically connected to the output end of the driving circuit through the electronic switch, and the charging circuit includes a third pnp transistor and a fifth voltage drop resistor; The emitter of the third pnp type transistor is electrically connected to the output end of the power supply circuit and the first end of the fifth voltage drop resistor, respectively; the base of the third pnp type transistor is electrically connected to the second end of the fifth voltage drop resistor and the input end of the electronic switch, respectively; and the collector of the third pnp type transistor is electrically connected to the base of the second npn type transistor, the first end of the fourth voltage drop resistor and the first end of the second capacitor, respectively.

7. The control circuit of the double-coil contactor according to claim 4, characterized in that: The input end of the charging circuit is electrically connected to the output end of the driving circuit through the electronic switch, and the charging circuit includes a first voltage-stabilizing diode and a sixth voltage-dropping resistor; A first end of the sixth voltage drop resistor is electrically connected to the output end of the electronic switch and the cathode of the first voltage stabilizing diode respectively, and a second end of the sixth voltage drop resistor is grounded.

8. The control circuit of the double-coil contactor according to claim 1, characterized in that: The control circuit of the dual-coil contactor also includes a voltage trigger circuit; The input end of the voltage trigger circuit is electrically connected to the output end of the power supply circuit, and the output end of the voltage trigger circuit is electrically connected to the input end of the bistable circuit; The voltage trigger circuit is used to output a voltage to the bistable circuit when the input voltage is greater than a preset voltage value.

9. The control circuit of the double-coil contactor according to claim 8, characterized in that: The voltage trigger circuit includes a second voltage stabilizing diode, a fourth pnp transistor, a third npn transistor, a seventh voltage drop resistor and an eighth voltage drop resistor; The cathode of the second voltage-regulating diode is electrically connected to the output end of the power supply circuit, the first end of the seventh voltage-drop resistor and the emitter of the fourth pnp type transistor, respectively; the anode of the second voltage-regulating diode is electrically connected to the base of the third npn type transistor and the first end of the eighth voltage-drop resistor, respectively; the base of the fourth pnp type transistor is electrically connected to the second end of the seventh voltage-drop resistor and the collector of the third npn type transistor, respectively; the collector of the fourth pnp type transistor is electrically connected to the input end of the bistable circuit, and the emitter of the third npn type transistor and the second end of the eighth voltage-drop resistor are grounded, respectively.

10. The control circuit of the double-coil contactor according to claim 1, characterized in that: The power supply circuit includes a surge protection circuit, a rectification circuit and a linear voltage stabilization circuit; The input end of the surge protection circuit is electrically connected to the power supply, the output end of the surge protection circuit is electrically connected to the input end of the rectifier circuit, the output end of the rectifier circuit is electrically connected to the input end of the linear voltage stabilization circuit and the power supply end of the dual-coil contactor respectively, and the output end of the linear voltage stabilization circuit is electrically connected to the input end of the bistable circuit.

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