Electromagnetic switch driving circuit, electromagnetic switch control circuit and contactor system

Abstract

The utility model provides an electromagnetic switch driving circuit, a control circuit of an electromagnetic switch and a contactor system. The electromagnetic switch driving circuit comprises a freewheeling transistor, a freewheeling switch, a master control switch, a bootstrap capacitor and a freewheeling diode. The freewheeling switch is additionally arranged to control the on-off of a circuit between the freewheeling transistor and the bootstrap capacitor, under the control of the main control circuit, after the main control switch is switched off, the freewheeling transistor can be quickly switched off, so that the bootstrap capacitor cannot discharge, the freewheeling transistor is quickly switched off, and the service life of the bootstrap capacitor is prolonged. Therefore, the freewheeling loop where the freewheeling diode and the coil of the electromagnetic switch are located is quickly disconnected, and the turn-off speed of the electromagnetic switch is finally improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic switches, in particular to an electromagnetic switch drive circuit, an electromagnetic switch control circuit and a contactor system. Background Art

[0002] Electromagnetic switches are electrical components used to control circuits, typically high-power loads. They open or close circuits based on changes in an input signal. Electromagnetic switches typically consist of a solenoid coil and a set of contacts that switch the circuit. When the solenoid coil is energized, it generates a magnetic field that closes the contacts. When the solenoid coil is de-energized, the contacts open, breaking the circuit.

[0003] The electromagnetic switch driver circuit used to drive the electromagnetic switch typically includes a corresponding freewheeling circuit. This circuit allows the energy in the electromagnetic switch coil to be discharged through the freewheeling circuit after the electromagnetic switch's output circuit is disconnected. When this discharge reaches a certain level, the magnetic force generated by the electromagnetic switch coil can no longer maintain the electromagnetic switch's on state, causing it to shut down. However, the freewheeling scheme in the target electromagnetic switch driver circuit results in a slow shutdown speed for the electromagnetic switch. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides an electromagnetic switch drive circuit, an electromagnetic switch control circuit and a contactor system.

[0005] In one embodiment, the present invention provides an electromagnetic switch driving circuit, the electromagnetic switch driving circuit comprising:

[0006] The main control switch is connected in series with the electromagnetic switch coil to turn on or off the power supply circuit where the electromagnetic switch coil is located;

[0007] A freewheeling circuit is connected in parallel with the electromagnetic switch coil to release energy in the electromagnetic switch coil, and the freewheeling circuit includes a freewheeling transistor and a freewheeling diode connected in series;

[0008] The freewheeling control circuit is used to control the conduction and cutoff of the freewheeling transistor. The freewheeling control circuit includes a freewheeling switch and a bootstrap capacitor. The controlled end of the freewheeling switch is used to connect to the main control circuit, the first access end of the freewheeling switch is connected to the bootstrap capacitor, the second access end of the freewheeling switch is connected to the freewheeling transistor, and the bootstrap capacitor is connected to the power supply circuit.

[0009] In one embodiment, the freewheeling transistor includes a freewheeling MOS transistor, and the electromagnetic switch driving circuit further includes a voltage drop resistor;

[0010] The cathode of the freewheeling diode, the drain of the freewheeling MOS tube, the first access terminal of the freewheeling switch and the first terminal of the bootstrap capacitor are respectively used to access the power supply voltage of the electromagnetic switch coil;

[0011] The gate of the freewheeling MOS transistor is electrically connected to the second access terminal of the freewheeling switch and the first end of the voltage drop resistor, respectively; the source of the freewheeling MOS transistor is electrically connected to the second end of the voltage drop resistor, the second end of the bootstrap capacitor, the anode of the freewheeling diode, and the first access terminal of the main control switch, respectively;

[0012] The second access terminal of the main control switch is grounded, and the controlled terminal of the main control switch is used to be electrically connected to the main control circuit;

[0013] The electromagnetic switch coil is connected in series with the freewheeling MOS tube and in parallel with the freewheeling diode.

[0014] In one embodiment, the freewheeling switch comprises an optocoupler;

[0015] The emitter of the phototransistor in the optocoupler is electrically connected to the gate of the freewheeling MOS tube and the first end of the voltage drop resistor respectively, and the collector of the phototransistor in the optocoupler is electrically connected to the first end of the bootstrap capacitor and the cathode of the freewheeling diode respectively;

[0016] The anode of the light-emitting diode in the optocoupler is used to access the working voltage, and the cathode of the light-emitting diode in the optocoupler is used to be electrically connected to the main control circuit.

[0017] In one embodiment, the electromagnetic switch driving circuit further includes a bidirectional TVS tube;

[0018] The first anode of the bidirectional TVS tube is electrically connected to the first access terminal of the freewheeling transistor, and the second anode of the bidirectional TVS tube is electrically connected to the second access terminal of the freewheeling transistor.

[0019] In one embodiment, the electromagnetic switch driving circuit further includes an anti-reverse diode;

[0020] The anode of the anti-reverse diode is electrically connected to the bootstrap capacitor, and the cathode of the anti-reverse diode is electrically connected to the power supply circuit.

[0021] In one embodiment, the electromagnetic switch coil includes a first electromagnetic switch coil and a second electromagnetic switch coil;

[0022] The main control switch is used to be connected in series with the first electromagnetic switch coil and the second electromagnetic switch coil to switch on or off the power supply circuit where the first electromagnetic switch coil and the second electromagnetic switch coil are located.

[0023] In a second aspect, in one embodiment, the present invention provides a control circuit for an electromagnetic switch, the control circuit for the electromagnetic switch including a main control circuit and the electromagnetic switch drive circuit of any of the above embodiments;

[0024] The main control circuit is electrically connected to the controlled end of the freewheeling switch in the electromagnetic switch driving circuit.

[0025] In one embodiment, the control circuit of the electromagnetic switch further includes a power supply circuit, wherein a common terminal of the cathode of the freewheeling diode in the electromagnetic switch driving circuit, the first access terminal of the freewheeling transistor, the first access terminal of the freewheeling switch, and the first terminal of the bootstrap capacitor serves as a power supply terminal of the electromagnetic switch driving circuit;

[0026] The input end of the power supply circuit is used to access the power supply, and the output end of the power supply circuit is electrically connected to the power supply end of the main control circuit and the power supply end of the electromagnetic switch drive circuit respectively.

[0027] In one embodiment, the power supply circuit includes an electromagnetic compatibility circuit and a step-down voltage stabilization circuit;

[0028] The input end of the electromagnetic compatibility circuit is used to access the power supply, the output end of the electromagnetic compatibility circuit is electrically connected to the input end of the step-down voltage stabilization circuit and the power supply end of the electromagnetic switch drive circuit respectively, and the output end of the step-down voltage stabilization circuit is electrically connected to the power supply end of the main control circuit.

[0029] In one embodiment, the electromagnetic compatibility circuit includes a surge protection circuit, a filter circuit, and a rectifier circuit;

[0030] The input end of the surge protection circuit is used to connect to the power supply, the output end of the surge protection circuit is electrically connected to the input end of the filter circuit, the output end of the filter circuit is electrically connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is electrically connected to the input end of the step-down voltage stabilization circuit and the power supply end of the electromagnetic switch drive circuit respectively.

[0031] In one embodiment, the buck voltage stabilization circuit includes a linear voltage stabilization circuit and a buck voltage stabilization chip;

[0032] The input end of the linear voltage regulator circuit is electrically connected to the output end of the electromagnetic compatibility circuit and the power supply end of the electromagnetic switch drive circuit respectively, the output end of the linear voltage regulator circuit is electrically connected to the input end of the buck voltage regulator chip, and the output end of the buck voltage regulator chip is electrically connected to the power supply end of the main control circuit.

[0033] In a third aspect, in one embodiment, the present invention provides a contactor system, the contactor system comprising an electromagnetic switch and a control circuit of the electromagnetic switch in any of the above embodiments, the electromagnetic switch comprising an electromagnetic switch coil;

[0034] The electromagnetic switch coil is connected in series with the main control switch in the electromagnetic switch drive circuit;

[0035] The main control switch is used to turn on or off the power supply circuit where the electromagnetic switch coil is located.

[0036] Through the above-mentioned electromagnetic switch drive circuit, electromagnetic switch control circuit and contactor system, a freewheeling switch is added to control the on-off of the circuit between the freewheeling transistor and the bootstrap capacitor. Under the control of the main control circuit, after the main control switch is disconnected, the freewheeling transistor can be quickly disconnected, resulting in the bootstrap capacitor being unable to discharge, thereby quickly disconnecting the freewheeling transistor, and then quickly disconnecting the freewheeling circuit where the freewheeling diode and the electromagnetic switch coil are located, ultimately improving the shutdown speed of the electromagnetic switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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.

[0038] Figure 1 This is a schematic diagram of the structure of the electromagnetic switch driving circuit in one embodiment of the present utility model;

[0039] Figure 2 This is a specific circuit diagram of an electromagnetic switch driving circuit in one embodiment of the present utility model;

[0040] Figure 3 This is a schematic diagram of the connection relationship of the driver chip in one embodiment of the present utility model;

[0041] Figure 4 This is a schematic diagram of the structure of an electromagnetic compatibility circuit in one embodiment of the present utility model;

[0042] Figure 5 This is a schematic structural diagram of a step-down voltage stabilizing circuit in one embodiment of the present utility model;

[0043] Figure 6 This is a schematic diagram of the connection relationship of the voltage step-down and voltage stabilization chip in one embodiment of the present utility model. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0045] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present application, "multiple" means two or more, unless otherwise expressly specified. In the present application, the word "exemplary" is used to mean "serving as an example, illustration, or explanation." Any embodiment described in the present application as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is provided to enable any person skilled in the art to implement and use the present invention. In the following description, details are listed for illustrative purposes. It should be understood that one of ordinary skill in the art will recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes are not described in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0046] First, as Figure 1 As shown, in one embodiment, the utility model provides an electromagnetic switch driving circuit.

[0047] The electromagnetic switch can be applied to a contactor, a relay, etc., and the subsequent content of this embodiment and subsequent embodiments will be described using "application to a contactor" as an example.

[0048] Among them, in this embodiment, taking the application of the electromagnetic switch to the contactor as an example, a contactor drive circuit can be specifically proposed, which includes a freewheeling MOS tube Q4, a freewheeling switch, a main control switch, a bootstrap capacitor C5, a voltage drop resistor R6 and a freewheeling diode D2.

[0049] In addition to the freewheeling MOS transistor Q4 , in other embodiments, other types of transistors may be used as the freewheeling transistor in this embodiment.

[0050] The freewheeling transistor (such as the freewheeling MOS tube Q4 ) and the freewheeling diode D2 form a freewheeling loop.

[0051] The freewheeling switch and the bootstrap capacitor C5 constitute a freewheeling control circuit.

[0052] exist Figure 1 In the circuit, the cathode of the freewheeling diode D2, the drain of the freewheeling MOS tube Q4, the first access terminal of the freewheeling switch and the first end of the bootstrap capacitor C5 are respectively used to access the supply voltage B1 of the contactor coil (including the first contactor coil coil_1 and the second contactor coil coil_2).

[0053] In other embodiments, when the electromagnetic switch is not a contactor, the corresponding contactor coil may be replaced with another type of electromagnetic switch coil.

[0054] exist Figure 1 In the embodiment, the gate of the freewheeling MOS tube Q4 is electrically connected to the second access terminal of the freewheeling switch and the first end of the voltage drop resistor R6, respectively, and the source of the freewheeling MOS tube Q4 is electrically connected to the second end of the voltage drop resistor R6, the second end of the bootstrap capacitor C5, the anode of the freewheeling diode D2 and the first access terminal of the main control switch.

[0055] exist Figure 1 In the embodiment, the second access terminal of the main control switch is grounded, the controlled terminal of the main control switch is used to be electrically connected to the main control circuit to receive the first control signal Ctrl input by the main control circuit, and the controlled terminal of the freewheeling switch is used to be electrically connected to the main control circuit to receive the second control signal Fast_Drive input by the main control circuit.

[0056] The first contactor coil coil_1 and the second contactor coil coil_2 are connected in series with the MOS tube and in parallel with the freewheeling diode D2.

[0057] When the main control circuit outputs a first control signal Ctrl, indicating conduction, to the controlled terminal of the main control switch and a second control signal Fast_Drive, indicating conduction, to the controlled terminal of the freewheeling switch, the main control switch and the freewheeling switch are turned on, and the incoming supply voltage B1 charges the bootstrap capacitor C5. After charging is complete, the incoming supply voltage B1 passes through the freewheeling switch, the voltage drop resistor R6, the second contactor coil coil_2, and the main control switch before reaching ground, forming a current loop. A voltage drop occurs across the voltage drop resistor R6, and the gate-source voltage of the freewheeling MOSFET Q4 meets its conduction requirements, turning on the freewheeling MOSFET Q4. The incoming supply voltage B1 passes through the first contactor coil coil_1, the freewheeling MOSFET Q4, the second contactor coil coil_2, and the main control switch before reaching ground, forming a current loop and turning on the contactor.

[0058] When the main control circuit outputs the first control signal Ctrl, indicating disconnection, to the controlled terminal of the main control switch and the second control signal Fast_Drive, indicating conduction, to the controlled terminal of the freewheeling switch, the main control switch is disconnected but the freewheeling switch is on, and the bootstrap capacitor C5 discharges through the voltage drop resistor R6. A voltage drop is generated across the voltage drop resistor R6, and the gate-source voltage of the freewheeling MOS transistor Q4 meets its conduction requirement, so the freewheeling MOS transistor Q4 remains on. The freewheeling circuit formed by the first contactor coil_1, the second contactor coil_2, and the freewheeling diode D2 is turned on, discharging the energy in the first contactor coil_1 and the second contactor coil_2, and the contactor remains on. If the main control circuit outputs the second control signal Fast_Drive, indicating disconnection, to the controlled terminal of the freewheeling switch at this time, the freewheeling switch is disconnected, and the bootstrap capacitor C5 can no longer discharge through the voltage drop resistor R6. No voltage drop occurs across the voltage-drop resistor R6, and the gate-source voltage of the freewheeling MOSFET Q4 fails to meet its conduction requirements, causing the freewheeling MOSFET Q4 to turn off. The freewheeling circuit formed by the first contactor coil_1, the second contactor coil_2, and the freewheeling diode D2 is disconnected. The energy in the first and second contactor coils coil_1 and coil_2 cannot be further discharged, causing the contactor to shut down.

[0059] In summary, in this embodiment, after adding the freewheeling switch, the main control circuit can maintain and interrupt the freewheeling current by controlling the on / off state of the freewheeling switch during the complete discharge time of the bootstrap capacitor C5, thereby enabling the contactor to be turned off before the discharge of the bootstrap capacitor C5 is completed. Compared with turning off the contactor after the discharge of the bootstrap capacitor C5 is completed, the shutdown speed is improved.

[0060] Among them, the double-coil contactor architecture shown in this embodiment is as follows: Figure 1 In the embodiment of the present invention, the first contactor coil coil_1 and the second contactor coil coil_2 are connected. One of the first contactor coil_1 and the second contactor coil coil_2 serves as a starting coil, and the other serves as a maintaining coil. In other embodiments, the present invention can also be applied to a single-coil contactor architecture. The contactor drive circuit in this application is applicable to both a dual-coil contactor architecture and a single-coil contactor architecture. When applied to a single-coil contactor architecture, its operating principle is the same as that of a dual-coil contactor architecture, and will not be further described here.

[0061] By using the above-mentioned contactor drive circuit, a freewheeling switch is added to control the on / off of the circuit between the gate of the freewheeling MOS tube and the first end of the bootstrap capacitor. Under the control of the main control circuit, after the main control switch is disconnected, the freewheeling MOS tube can be quickly disconnected, resulting in the bootstrap capacitor being unable to discharge through the voltage drop resistor, thereby quickly disconnecting the MOS tube, and further quickly disconnecting the freewheeling circuit where the freewheeling diode and the contactor coil are located, ultimately improving the shutdown speed of the contactor.

[0062] like Figure 2 As shown, in one embodiment, the freewheeling switch includes an optocoupler U3.

[0063] exist Figure 2 In the embodiment, the emitter of the phototransistor in the optocoupler U3 is electrically connected to the gate of the freewheeling MOS tube Q4 and the first end of the voltage drop resistor R6 through the resistor R10, and the collector of the phototransistor in the optocoupler U3 is electrically connected to the first end of the bootstrap capacitor C5 and the cathode of the freewheeling diode D2.

[0064] exist Figure 2 In the embodiment, the anode of the light emitting diode in the optocoupler U3 is used to access the working voltage (such as +5V working voltage) through the resistor R18, and the cathode of the light emitting diode in the optocoupler U3 is electrically connected to the main control circuit.

[0065] When the main control circuit outputs a low-level second control signal Fast_Drive, indicating conduction, to the cathode of the light-emitting diode in the optocoupler U3, a sufficient forward voltage difference is generated across the light-emitting diode in the optocoupler U3, current flows through the light-emitting diode in the optocoupler U3, and the light-emitting diode in the optocoupler U3 emits light, turning on the phototransistor in the optocoupler U3. Conversely, when the main control circuit outputs a high-level second control signal Fast_Drive, indicating disconnection, to the cathode of the light-emitting diode in the optocoupler U3, a sufficient forward voltage difference is not generated across the light-emitting diode in the optocoupler U3, current does not flow through the light-emitting diode in the optocoupler U3, and the light-emitting diode in the optocoupler U3 does not emit light, turning off the phototransistor in the optocoupler U3.

[0066] The optocoupler U3 has a signal isolation function, which can prevent the second control signal Fast_Drive from interfering with other electronic components (such as the bootstrap capacitor C5).

[0067] like Figure 2 As shown, in one embodiment, the contactor drive circuit further includes a bidirectional TVS tube D3.

[0068] exist Figure 2 In the embodiment, the first anode of the bidirectional TVS tube D3 is electrically connected to the drain of the freewheeling MOS tube Q4, and the second anode of the bidirectional TVS tube D3 is electrically connected to the source of the freewheeling MOS tube Q4.

[0069] The currents in the first contactor coils coil_1 and coil_2 may vary. When the currents are high, after the freewheeling MOSFET Q4 is disconnected, a large surge voltage may be generated in the first contactor coils coil_1 and coil_2, which could easily damage the freewheeling MOSFET Q4. Therefore, in this embodiment, a bidirectional TVS diode D3 is added to clamp the voltage between the drain and source of the freewheeling MOSFET Q4, preventing excessive surge voltages in the first contactor coils coil_1 and coil_2 after the freewheeling MOSFET Q4 is disconnected, which could damage the freewheeling MOSFET Q4.

[0070] It should be noted that when the first contactor coil coil_1 and the first contactor coil coil_2 operate at high current, the contactor's turn-off speed depends on the clamping threshold of the bidirectional TVS tube D3; when the first contactor coil coil_1 and the first contactor coil coil_2 operate at low current, the contactor's turn-off speed depends on the turn-off speed of the optocoupler U3.

[0071] like Figure 2 As shown, in one embodiment, the contactor drive circuit further includes an anti-reverse diode D4.

[0072] exist Figure 2 In the embodiment, the anode of the anti-reverse diode D4 is electrically connected to the second end of the bootstrap capacitor C5, and the cathode of the anti-reverse diode D4 is electrically connected to the source of the freewheeling MOS tube Q4.

[0073] The anti-reverse diode D4 can prevent energy from flowing back from the output end.

[0074] like Figure 2 As shown, in one embodiment, the main control switch includes a main control MOS transistor Q5.

[0075] exist Figure 2 In the embodiment, the gate of the main control MOS transistor Q5 is used to access the first control signal Ctrl output by the main control circuit through a voltage divider network composed of a resistor R13 and a resistor R17.

[0076] Among them, Figure 2 The contactor drive circuit further includes a bidirectional TVS transistor D5. The bidirectional TVS transistor D5 is used to clamp the voltage between the drain and source of the main control MOS transistor Q5 to prevent the main control MOS transistor Q5 from being damaged due to excessive voltage between its drain and source after it is disconnected.

[0077] like Figure 2 As shown, in one embodiment, the contactor drive circuit further includes a Zener diode ZD1.

[0078] exist Figure 2In the embodiment, the cathode of the Zener diode ZD1 is electrically connected to the first end of the bootstrap capacitor C5, and the anode of the Zener diode ZD1 is electrically connected to the second end of the bootstrap capacitor C5.

[0079] The voltage stabilizing diode ZD1 is used to limit the voltage provided to the gate of the freewheeling MOS transistor Q4 , thereby enabling the freewheeling MOS transistor Q4 to operate within a stable voltage range.

[0080] In a second aspect, in one embodiment, the present invention provides a control circuit for an electromagnetic switch.

[0081] In this embodiment, taking the electromagnetic switch as a contactor as an example, a control circuit of the contactor can be specifically proposed, and the control circuit of the contactor includes a main control circuit and the contactor drive circuit in any of the above embodiments;

[0082] The main control circuit is electrically connected to the controlled end of the freewheeling switch and the controlled end of the main control switch in the contactor drive circuit respectively.

[0083] Through the control circuit of the above-mentioned contactor, a freewheeling switch is added to control the on / off of the circuit between the gate of the freewheeling MOS tube and the first end of the bootstrap capacitor. Under the control of the main control circuit, after the main control switch is disconnected, the freewheeling MOS tube can be quickly disconnected, resulting in the bootstrap capacitor being unable to discharge through the voltage drop resistor, thereby causing the MOS tube to be quickly disconnected, and then the freewheeling circuit where the freewheeling diode and the contactor coil are located is quickly disconnected, ultimately improving the shutdown speed of the contactor.

[0084] like Figure 3 As shown, in one embodiment, the control circuit of the contactor further includes a driver chip U2.

[0085] The power supply terminal VDD of the driver chip U2 is electrically connected to the output terminal of the power supply circuit to receive the +12V voltage output by the power supply circuit.

[0086] Among them, the input terminal IN+ of the driver chip U2 is electrically connected to the output terminal of the main control circuit to receive the voltage signal PWM output by the main control circuit, and the output terminal OUT of the driver chip U2 is electrically connected to the gate of the main control MOS tube Q5 to output the first control signal Ctrl.

[0087] When the PWM signal output by the main control circuit is high, the driver chip U2 outputs a high-level first control signal Ctrl; otherwise, when the PWM signal output by the main control circuit is low, the driver chip U2 outputs a low-level first control signal Ctrl.

[0088] In one embodiment, the control circuit of the contactor further includes a power supply circuit, and a common end of the cathode of the freewheeling diode, the drain of the freewheeling MOS transistor, the first access end of the freewheeling switch, and the first end of the bootstrap capacitor in the contactor drive circuit serves as a power supply end of the contactor drive circuit;

[0089] The input end of the power supply circuit is used to access the power supply, and the output end of the power supply circuit is electrically connected to the power supply end of the main control circuit and the power supply end of the contactor drive circuit respectively.

[0090] In one embodiment, the power supply circuit includes an electromagnetic compatibility circuit and a step-down voltage stabilization circuit;

[0091] The input end of the electromagnetic compatibility circuit is used to access the power supply, the output end of the electromagnetic compatibility circuit is electrically connected to the input end of the step-down voltage stabilization circuit and the power supply end of the contactor drive circuit respectively, and the output end of the step-down voltage stabilization circuit is electrically connected to the power supply end of the main control circuit.

[0092] Among them, the back-stage circuit requires the power supply circuit to output voltage signals of different voltage amplitudes for power supply, so the electromagnetic compatibility circuit can output a voltage signal with a relatively large voltage amplitude to be used for the first aspect of power supply to the contactor drive circuit (mainly used for outputting Figure 2 The step-down voltage stabilizing circuit can step down the voltage output by the electromagnetic compatibility circuit to obtain a voltage signal with a relatively small voltage amplitude, which can be used to power the contactor drive circuit in the second aspect (mainly used for outputting Figure 2 The +5V working voltage is used to power the optocoupler U3), the main control circuit, and the driver chip U2.

[0093] like Figure 4 As shown, in one embodiment, the electromagnetic compatibility circuit includes a surge protection circuit (including a varistor RV1), a filter circuit (including an inductor L1, an inductor L2, an inductor L3, a capacitor C1, and a capacitor C2) and a rectifier circuit (including a rectifier bridge BR1).

[0094] Among them, the input end of the varistor RV1 is electrically connected to the output end of the power supply (such as electrically connected to the live wire L and the neutral wire N), the output end of the varistor RV1 is electrically connected to the input end of the inductor L1 and the input end of the inductor L3 respectively, the output end of the capacitor C2 is electrically connected to the input end of the rectifier bridge BR1, and the output end of the rectifier bridge BR1 is electrically connected to the input end of the step-down voltage stabilization circuit and the first power supply end of the contactor drive circuit respectively to output the supply voltage B1.

[0095] like Figure 5 and Figure 6As shown, in one embodiment, the buck voltage stabilization circuit includes a linear voltage stabilization circuit (including a voltage stabilization diode D1 , a transistor Q1 , a transistor Q2 , and a transistor Q3 ) and a buck voltage stabilization chip VOT1 .

[0096] Among them, the collector and base of the transistor Q1 are electrically connected to the output end of the electromagnetic compatibility circuit and the power supply end of the contactor drive circuit respectively to access the power supply voltage B1 output by the electromagnetic compatibility circuit. The emitter of the transistor Q3 is electrically connected to the input end of the buck regulator chip VOT1 to output a +12V voltage. The output end of the buck regulator chip VOT1 is electrically connected to the power supply end of the main control circuit to output a +5V voltage.

[0097] like Figure 5 As shown, in one embodiment, the control circuit of the contactor further includes a voltage feedback circuit consisting of a resistor R3, a resistor R4, a resistor R5, a resistor R9, a resistor R12, a capacitor C4, and a bidirectional TVS diode TVS1. The first end of the resistor R3 is used to connect to the supply voltage B1, and the first anode of the bidirectional TVS diode TVS1 is used to be electrically connected to the feedback end of the main control circuit to output a feedback voltage VF to the main control circuit.

[0098] The main control circuit can judge the current power supply status according to the input feedback voltage VF, thereby completing the relevant control more reliably.

[0099] It should be noted that Figures 3 to 6 The components not mentioned in the above embodiments are all basic components for realizing the basic functions of the circuit, and their connection relationships and principles and functions will not be described in detail here.

[0100] In a third aspect, in one embodiment, the present invention provides a contactor system.

[0101] The contactor system includes a contactor and a control circuit of the contactor in any one of the above embodiments, and the contactor includes a first contactor coil and a second contactor coil.

[0102] The first end of the first contactor coil is electrically connected to the cathode of the freewheeling diode, the first access end of the freewheeling switch and the first end of the bootstrap capacitor in the contactor drive circuit, and the second end of the first contactor coil is electrically connected to the drain of the freewheeling MOS transistor;

[0103] The first end of the second contactor coil is electrically connected to the source of the freewheeling MOS tube, the second end of the voltage drop resistor and the second end of the bootstrap capacitor respectively, and the second end of the second contactor coil is electrically connected to the anode of the freewheeling diode and the first access end of the main control switch respectively.

[0104] The connection relationship between the first contactor coil, the second contactor coil and the control circuit of the contactor can refer to the above embodiment and will not be repeated here.

[0105] In other embodiments, the contactor may also include only one contactor coil.

[0106] With the above-mentioned contactor system, a freewheeling switch is added to control the on / off of the circuit between the gate of the freewheeling MOS transistor and the first end of the bootstrap capacitor. Under the control of the main control circuit, after the main control switch is disconnected, the freewheeling MOS transistor can be quickly disconnected, resulting in the bootstrap capacitor being unable to discharge through the voltage drop resistor, thereby quickly disconnecting the freewheeling MOS transistor, and then quickly disconnecting the freewheeling circuit where the freewheeling diode and the contactor coil are located, ultimately improving the shutdown speed of the contactor.

[0107] In the above embodiments, the description of each embodiment has its own focus. 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.

[0108] The above is a detailed introduction to an electromagnetic switch drive circuit, an electromagnetic switch control circuit and an electromagnetic switch system provided by the utility model. Specific examples are used in this article to illustrate the principles and implementation methods 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 technical personnel in this field, based on 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.

[0109] The technical features of the above embodiments can 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. An electromagnetic switch driving circuit, characterized in that: The electromagnetic switch driving circuit includes: A main control switch is connected in series with the electromagnetic switch coil to switch on or off the power supply circuit where the electromagnetic switch coil is located; a freewheeling circuit, connected in parallel with the electromagnetic switch coil to release energy in the electromagnetic switch coil, the freewheeling circuit comprising a freewheeling transistor and a freewheeling diode connected in series; A freewheeling control circuit is used to control the conduction and cutoff of the freewheeling transistor. The freewheeling control circuit includes a freewheeling switch and a bootstrap capacitor. The controlled end of the freewheeling switch is used to connect to the main control circuit, the first access end of the freewheeling switch is connected to the bootstrap capacitor, the second access end of the freewheeling switch is connected to the freewheeling transistor, and the bootstrap capacitor is connected to the power supply circuit.

2. The electromagnetic switch driving circuit according to claim 1, characterized in that: The freewheeling transistor includes a freewheeling MOS tube, and the electromagnetic switch driving circuit also includes a voltage drop resistor; The cathode of the freewheeling diode, the drain of the freewheeling MOS tube, the first access terminal of the freewheeling switch and the first terminal of the bootstrap capacitor are respectively used to access the power supply voltage of the electromagnetic switch coil; The gate of the freewheeling MOS transistor is electrically connected to the second access terminal of the freewheeling switch and the first end of the voltage drop resistor, respectively; the source of the freewheeling MOS transistor is electrically connected to the second end of the voltage drop resistor, the second end of the bootstrap capacitor, the anode of the freewheeling diode, and the first access terminal of the main control switch, respectively; The second access terminal of the main control switch is grounded, and the controlled terminal of the main control switch is used to be electrically connected to the main control circuit; The electromagnetic switch coil is connected in series with the freewheeling MOS tube and in parallel with the freewheeling diode.

3. The electromagnetic switch driving circuit according to claim 2, characterized in that: The freewheeling switch includes an optocoupler; The emitter of the phototransistor in the optocoupler is electrically connected to the gate of the freewheeling MOS tube and the first end of the voltage drop resistor, respectively, and the collector of the phototransistor in the optocoupler is electrically connected to the first end of the bootstrap capacitor and the cathode of the freewheeling diode, respectively; The anode of the light emitting diode in the optocoupler is used to access the working voltage, and the cathode of the light emitting diode in the optocoupler is used to be electrically connected to the main control circuit.

4. The electromagnetic switch driving circuit according to claim 1, characterized in that: The electromagnetic switch driving circuit also includes a bidirectional TVS tube; The first anode of the bidirectional TVS tube is electrically connected to the first access terminal of the freewheeling transistor, and the second anode of the bidirectional TVS tube is electrically connected to the second access terminal of the freewheeling transistor.

5. The electromagnetic switch driving circuit according to claim 1, characterized in that: The electromagnetic switch driving circuit further includes an anti-reverse diode; The anode of the anti-reverse diode is electrically connected to the bootstrap capacitor, and the cathode of the anti-reverse diode is electrically connected to the power supply circuit.

6. The electromagnetic switch driving circuit according to claim 1, characterized in that: The electromagnetic switch coil includes a first electromagnetic switch coil and a second electromagnetic switch coil; The main control switch is used to be connected in series with the first electromagnetic switch coil and the second electromagnetic switch coil to switch on or off the power supply circuit where the first electromagnetic switch coil and the second electromagnetic switch coil are located.

7. A control circuit for an electromagnetic switch, characterized in that: The control circuit of the electromagnetic switch includes a main control circuit and the electromagnetic switch drive circuit according to any one of claims 1 to 6; The main control circuit is electrically connected to the controlled end of the freewheeling switch in the electromagnetic switch driving circuit.

8. The control circuit of the electromagnetic switch according to claim 7, characterized in that: The control circuit of the electromagnetic switch further includes a power supply circuit, wherein a common terminal of the cathode of the freewheeling diode in the electromagnetic switch driving circuit, the first access terminal of the freewheeling transistor, the first access terminal of the freewheeling switch, and the first terminal of the bootstrap capacitor serves as a power supply terminal of the electromagnetic switch driving circuit; The input end of the power supply circuit is used to access the power supply, and the output end of the power supply circuit is electrically connected to the power supply end of the main control circuit and the power supply end of the electromagnetic switch drive circuit respectively.

9. The control circuit of the electromagnetic switch according to claim 8, characterized in that: The power supply circuit includes an electromagnetic compatibility circuit and a step-down voltage stabilization circuit; The input end of the electromagnetic compatibility circuit is used to connect to the power supply, the output end of the electromagnetic compatibility circuit is electrically connected to the input end of the step-down voltage stabilization circuit and the power supply end of the electromagnetic switch drive circuit respectively, and the output end of the step-down voltage stabilization circuit is electrically connected to the power supply end of the main control circuit.

10. The control circuit of the electromagnetic switch according to claim 9, characterized in that: The electromagnetic compatibility circuit includes a surge protection circuit, a filter circuit and a rectifier circuit; The input end of the surge protection circuit is used to connect to the power supply, the output end of the surge protection circuit is electrically connected to the input end of the filter circuit, the output end of the filter circuit is electrically connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is electrically connected to the input end of the step-down voltage stabilization circuit and the power supply end of the electromagnetic switch drive circuit respectively.

11. The control circuit of the electromagnetic switch according to claim 9, characterized in that: The step-down voltage stabilization circuit includes a linear voltage stabilization circuit and a step-down voltage stabilization chip; The input end of the linear voltage regulator circuit is electrically connected to the output end of the electromagnetic compatibility circuit and the power supply end of the electromagnetic switch drive circuit respectively, the output end of the linear voltage regulator circuit is electrically connected to the input end of the buck voltage regulator chip, and the output end of the buck voltage regulator chip is electrically connected to the power supply end of the main control circuit.

12. A contactor system, characterized in that: The contactor system comprises an electromagnetic switch and a control circuit for the electromagnetic switch according to any one of claims 7 to 11, wherein the electromagnetic switch comprises an electromagnetic switch coil; The electromagnetic switch coil is connected in series with the main control switch in the electromagnetic switch drive circuit; The main control switch is used to turn on or off the power supply circuit where the electromagnetic switch coil is located.

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