Control circuit and device for a direct current contactor

Abstract

The application provides a control circuit and device of a direct current contactor, the control circuit of the direct current contactor comprising a direct current contactor and a feedback circuit connected in series with auxiliary contacts of the direct current contactor, the feedback circuit being used for feeding back on-off states of main contacts through on-off of the auxiliary contacts; the feedback circuit comprising a photocoupler driving unit, a photocoupler receiving unit and a first resistor R1; the first resistor R1 being connected in parallel with the photocoupler driving unit. By connecting the first resistor R1 in parallel with the photocoupler driving unit, the application can effectively increase the current through the auxiliary contacts, ensure reliable attraction of the auxiliary contacts, and at the same time, does not increase the current burden of the photocoupler driving unit, thereby realizing accurate feedback on the on-off states of the main contacts.

Description

Technical Field

[0001] This invention belongs to the field of electrical equipment technology, specifically relating to a control circuit and device for a DC contactor. Background Technology

[0002] High-voltage DC contactors (such as 1500Vdc or 600Vdc) are widely used in energy storage systems, industrial automation and electric vehicles. Their main contacts are responsible for switching the high-voltage circuit on and off, while the auxiliary contacts are used to feed back the engagement status of the main contacts to the microcontroller (MCU) or other control units to achieve system monitoring and safety control.

[0003] However, in practical applications, auxiliary contacts require a certain minimum current to ensure the mechanical and electrical reliability of their switching engagement. But in existing technologies, due to insufficient feedback current, auxiliary contacts often fail to engage reliably, and may even exhibit jitter. This causes the microcontroller to be unable to correctly detect the state of the main contacts, thus affecting the normal operation and safety of the equipment. Furthermore, auxiliary contacts require a large feedback current, but the input current of the optocoupler cannot be too high, making the design of the feedback circuit and the selection of optocoupler components difficult, especially in high-voltage, high-current applications.

[0004] Therefore, designing a control circuit for a DC contactor that can increase the current passing through the auxiliary contacts of the DC contactor has become a technical problem that urgently needs to be solved by those skilled in the art.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] This invention provides a control circuit for a DC contactor, aiming to solve the problem that the auxiliary contacts of existing DC contactors cannot reliably engage due to insufficient feedback current.

[0007] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0008] A control circuit for a DC contactor includes a DC contactor and a feedback circuit connected in series with an auxiliary contact of the DC contactor. The feedback circuit is used to provide feedback on the on / off state of the main contact through the on / off state of the auxiliary contact. The feedback circuit includes an optocoupler driving unit, an optocoupler receiving unit, and a first resistor R1. The first resistor R1 is connected in parallel with the optocoupler driving unit.

[0009] Furthermore, the resistance value of the first resistor R1 is less than or equal to a preset value; when the resistance value of the first resistor R1 is equal to the preset value, the current through the auxiliary contact is the minimum current required to make the auxiliary contact close.

[0010] Preferably, the resistance value of the first resistor R1 is equal to a preset value.

[0011] Furthermore, the first resistor R1 is a single resistor; or, the first resistor R1 is composed of multiple sub-shunt resistors, which are connected in series and / or in parallel.

[0012] Preferably, the first resistor R1 is composed of multiple parallel sub-shunt resistors.

[0013] Furthermore, the first resistor R1 is mounted on a heat dissipation substrate, which is used to dissipate the heat of the first resistor R1.

[0014] Preferably, the heat dissipation substrate is an aluminum substrate;

[0015] Preferably, a heat sink is provided on the heat dissipation substrate.

[0016] Furthermore, the optocoupler driving unit includes an optical signal transmitter and a second resistor R2 connected in series with the optical signal transmitter; the end of the optical signal transmitter away from the connection with the second resistor R2 is connected to the negative terminal of the power supply; one end of the first resistor R1 is connected between the auxiliary contact and the second resistor R2, and the other end of the first resistor R1 is connected between the optical signal transmitter and the negative terminal of the power supply.

[0017] Furthermore, the resistance value of the first resistor R1 is less than the resistance value of the second resistor R2.

[0018] Furthermore, the DC contactor also includes a coil and main contacts. The A1 and A2 ends of the coil are connected to the positive and negative terminals of the external control circuit, respectively. One end of the auxiliary contact is connected to the positive terminal of the power supply, and the other end is connected to the negative terminal of the power supply through an optocoupler drive unit connected in parallel with the first resistor R1.

[0019] Furthermore, the optocoupler receiving unit is connected to the input terminal of the microcontroller, and the optocoupler receiving unit outputs a low-level signal F1 to the microcontroller when the auxiliary contact is closed.

[0020] Furthermore, the optocoupler receiving unit includes an optical signal receiver, a third resistor R3, a fourth resistor R4, and a capacitor C1; the low-potential end of the optical signal receiver is grounded, and the output end of the optical signal receiver is connected to one end of the third resistor R3 and one end of the fourth resistor R4 respectively; the other end of the third resistor R3 is connected to the positive terminal of the power supply, and the other end of the fourth resistor R4 is grounded through the capacitor C1.

[0021] Another object of the present invention is to provide a control device for a DC contactor, having a control circuit for the DC contactor.

[0022] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0023] 1. This invention, by connecting the first resistor R1 in parallel with the optocoupler drive unit, effectively increases the current through the auxiliary contacts, ensuring reliable engagement of the auxiliary contacts, without increasing the current burden on the optocoupler drive unit, thereby achieving accurate feedback on the on / off state of the main contacts. This invention has a simple structure, high reliability, and is suitable for feedback control applications of DC contactors.

[0024] 2. By setting the resistance value of the first resistor R1 to be less than or equal to a preset value, the present invention ensures that the current through the auxiliary contact meets the minimum current required for the auxiliary contact to close, thereby ensuring the reliable closing of the auxiliary contact and avoiding the problem of failure to close due to insufficient current.

[0025] 3. This invention effectively distributes the power load of the first resistor R1 by setting it as a first resistor composed of multiple sub-shunt resistors, and by connecting these sub-shunt resistors in series and / or parallel. This reduces the heat generation of the first resistor R1, thereby reducing its temperature rise and improving the heat dissipation performance and overall reliability of the control circuit. Simultaneously, this design also extends the service life of the first resistor R1, preventing control circuit failures caused by overheating and meeting the needs of high-power applications.

[0026] 4. By mounting the first resistor R1 on an aluminum substrate, the good thermal conductivity of the aluminum substrate effectively disperses the heat generated by the first resistor R1 during operation, further improving the heat dissipation efficiency.

[0027] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0028] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0029] Figure 1 This is a schematic diagram of the control circuit of the DC contactor in an embodiment of the present invention.

[0030] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0032] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] High-voltage DC contactors are widely used in energy storage systems, industrial automation, and electric vehicles. Their auxiliary contacts are used to provide feedback to the microcontroller on the engagement status of the main contacts. However, the auxiliary contacts require a minimum current to ensure their mechanical and electrical reliability when engaged. Insufficient feedback current often leads to unreliable contact engagement or chattering, causing the microcontroller to fail to accurately detect the main contact status and affecting the normal operation and safety of the equipment. Furthermore, there is a conflict between the large feedback current required by the auxiliary contacts and the input current limitation of the optocoupler, which complicates the feedback circuit design, especially in high-voltage, high-current applications.

[0035] like Figure 1 As shown in the embodiment of the present invention, a control circuit for a DC contactor is introduced to solve the above-mentioned technical problems.

[0036] In this embodiment, the control circuit of the DC contactor includes a DC contactor and a feedback circuit connected in series with the auxiliary contacts of the DC contactor. The feedback circuit is used to provide feedback on the on / off state of the main contacts through the on / off state of the auxiliary contacts. The feedback circuit includes an optocoupler driving unit, an optocoupler receiving unit, and a first resistor R1. The first resistor R1 is connected in parallel with the optocoupler driving unit to increase the current through the auxiliary contacts, so as to solve the problem of unreliable engagement of the auxiliary contacts due to insufficient feedback current.

[0037] In this embodiment, the optocoupler driving unit includes a light signal transmitter and a second resistor R2 connected in series with the light signal transmitter. The second resistor R2 is used to limit the current passing through the light signal transmitter and to feed back the auxiliary contact engagement state to the microcontroller or other control device in the form of a light signal. Further, the light signal transmitter is an optocoupler input LED.

[0038] Specifically, in this embodiment, when the auxiliary contact is closed, part of the current flows through the optocoupler driving unit, and the current magnitude is controlled by the second resistor R2 to ensure that the optocoupler works normally; the other part flows through the first resistor R1. Since the resistance of the first resistor R1 is small, this part of the current significantly increases the total current through the auxiliary contact, thereby meeting the minimum current required for reliable engagement of the auxiliary contact.

[0039] In this embodiment, the resistance value of the first resistor R1 is less than or equal to a preset value; when the resistance value of the first resistor R1 is equal to the preset value, the current through the auxiliary contact is the minimum current required for the auxiliary contact to close, thereby ensuring the reliable closing of the auxiliary contact and ensuring the normal operation of the DC contactor.

[0040] Specifically, in this embodiment, by adjusting the resistance value of the first resistor R1, the current shunt ratio can be flexibly set to ensure the pull-in current requirement of the auxiliary contact while ensuring the safe operation of the optocoupler drive unit.

[0041] Preferably, in this embodiment, the resistance value of the first resistor R1 is equal to the preset value; at this time, the current through the auxiliary contact is precisely calculated and verified during the design, so that it not only meets the minimum current required for the auxiliary contact to close, but also does not cause unnecessary energy loss or component heating due to excessive current, thereby further improving the working efficiency and reliability of the control circuit.

[0042] In practical applications, if the minimum current required for the auxiliary contact to close is 200mA, the preset resistance value of the first resistor R1 is 60Ω. With a power supply voltage of 12V, the current flowing through the auxiliary contact is I = U / R = 12V / 60Ω = 200mA. At this time, the power consumption of the first resistor R1 is...

[0043] P = I 2 ×R=(0.2A) 2 ×60Ω=2.4W, which satisfies the minimum current requirement for auxiliary contact engagement and ensures that the power loss of the first resistor R1 is within a safe range, thus ensuring the stable operation of the DC contactor's control circuit.

[0044] More specifically, in this embodiment, the resistance value of the first resistor R1 is less than that of the second resistor R2 to reasonably distribute the total current flowing through the auxiliary contact. Specifically, the first resistor R1 shares the main current of the auxiliary contact, while the second resistor R2 limits the current of the optical signal transmitter. For example, when the total current required for the auxiliary contact to close is 200mA, and the operating current of the optical signal transmitter is 20mA, the resistance values ​​of the first resistor R1 and R2 can be designed to be 100Ω and 1kΩ, respectively, to achieve a reasonable current distribution. Approximately 180mA of current flows through the first resistor R1, while 20mA flows through R2, thus meeting the requirement for reliable contact closure while protecting the normal operation of the optical signal transmitter. This ensures sufficient current for the auxiliary contact to close and effectively prevents damage to the optical signal transmitter due to overcurrent, improving the stability and reliability of the control circuit.

[0045] In the above embodiments, the problem of unreliable engagement of the auxiliary contacts due to insufficient feedback current is solved by connecting the first resistor R1 in parallel with the optocoupler driving unit, while ensuring the safe operation of the optical signal transmitter. This device has a simple structure, flexible design, and improves the working stability of the auxiliary contacts, making it suitable for various application scenarios of high-voltage DC contactors.

[0046] In this embodiment, the first resistor R1 is a single resistor; or, the first resistor R1 is composed of multiple sub-shunt resistors, which are connected in series and / or in parallel; used to reduce the heat generation of each first resistor R1.

[0047] Specifically, in this embodiment, the first resistor R1 can be designed as a single resistor. When the current required in the circuit is small and the power loss of the first resistor R1 is within the range of a single resistor, a single first resistor R1 can meet the requirements.

[0048] Specifically, in this embodiment, when the circuit needs to handle a large current, or when the power loss of the first resistor R1 exceeds the safe range of a single resistor, a design can be adopted to form the first resistor R1 by setting multiple sub-shunt resistors. Multiple sub-shunt resistors can be connected in series, parallel, or a combination of series and parallel connections to reduce the power load on the first resistor R1.

[0049] In one specific embodiment, multiple sub-shunt resistors are connected in parallel to ensure that the resistance value of the first resistor R1 meets the requirements, while distributing the current through each sub-shunt resistor. For example, four 800Ω sub-shunt resistors are connected in parallel to form a 200Ω first resistor R1, with each sub-shunt resistor sharing one-quarter of the current, thereby significantly reducing the heat generated by the first resistor R1.

[0050] In another specific embodiment, when it is necessary to increase the voltage withstand capability of the first resistor R1, multiple sub-shunt resistors can be connected in series. For example, two 100Ω sub-shunt resistors can be connected in series to form a 200Ω first resistor R1 to distribute voltage and heat and prevent the first resistor R1 from being damaged due to high voltage or high temperature.

[0051] In another specific embodiment, a series-parallel combination design of sub-shunt resistors can be adopted to cope with complex application scenarios, which not only meets the equivalent resistance requirements, but also effectively disperses heat and ensures the safety and stability of the first resistor R1 during long-term operation.

[0052] In this embodiment, the first resistor R1 is mounted on a heat dissipation substrate. The heat dissipation substrate is used to disperse the heat of the first resistor R1. By uniformly arranging the sub-shunt resistors of the first resistor R1 on the heat dissipation substrate and utilizing the high thermal conductivity of the heat dissipation substrate, the heat generated by the first resistor R1 during operation is dispersed, reducing the temperature rise of the first resistor R1, thereby improving the long-term reliability of the first resistor R1 and the stability of the entire device.

[0053] Preferably, in this embodiment, the heat dissipation substrate is an aluminum substrate. The aluminum substrate has excellent thermal conductivity, which can quickly conduct the heat generated by the first resistor R1 to the surface of the aluminum substrate, and dissipate the heat to the external environment through natural convection or additional heat dissipation measures (such as heat sinks), thereby improving heat dissipation efficiency.

[0054] Specifically, in this embodiment, multiple sub-shunt resistors are evenly distributed on the surface of the aluminum substrate to prevent heat from concentrating in local areas and improve heat dissipation.

[0055] In one possible embodiment, the first resistor R1 is connected to the aluminum substrate by thermally conductive adhesive or thermally conductive pad to reduce thermal resistance and enhance thermal conductivity.

[0056] Preferably, in this embodiment, a heat sink is provided on the aluminum substrate. When the power consumption of the first resistor R1 is large, the heat generated by the multiple parallel sub-shunt resistors will be evenly distributed on the heat sink substrate and then quickly dissipated through the heat sink, so that the surface temperature of the first resistor R1 is controlled within the safe operating range.

[0057] In some possible specific embodiments, when the total power consumption of the first resistor R1 reaches more than 10W, the heat sink installed on the aluminum substrate is a vertical heat sink, and combined with air cooling measures, the heat is quickly dissipated to the surrounding environment.

[0058] More specifically, the heat sink can be a one-piece heat sink, heat sink fins, or other forms of heat dissipation structure. The heat sink is in close contact with the heat sink base plate, which further promotes the rapid diffusion and dissipation of heat by increasing the heat dissipation area and improving the heat conduction efficiency.

[0059] Through the above design, this embodiment achieves efficient heat dissipation by mounting the first resistor R1 on an aluminum substrate, avoiding the performance degradation of the first resistor R1 due to overheating. Simultaneously, using an aluminum substrate as a heat dissipation substrate further improves the device's heat dissipation capacity, enabling it to adapt to high-power, high-reliability industrial scenarios and meet the requirements for long-term stable operation.

[0060] In this embodiment, the DC contactor further includes a coil and main contacts. Terminals A1 and A2 of the coil are connected to the positive and negative terminals of an external control circuit, respectively, to receive control signals provided by the external control circuit. When the control signal acts on the coil, the coil generates electromagnetic force to drive the main contacts to close or open, thereby realizing the on / off control of the high-voltage main circuit. Further, the high-voltage main circuit is a main power circuit controlled by the DC contactor, which connects or disconnects the high-voltage DC power through the main contacts to provide or disconnect power to the load.

[0061] In this embodiment, one end of the auxiliary contact is connected to the positive terminal of the power supply, and the other end is connected to the negative terminal of the power supply through an optocoupler driving unit connected in parallel with the first resistor R1. The parallel connection of the first resistor R1 and the optocoupler driving unit is used to share a portion of the current when the auxiliary contact is closed, thereby increasing the total current passing through the auxiliary contact. Furthermore, the positive terminal of the power supply connected to one end of the auxiliary contact is 5-110V DC (Vdc), and the negative terminal of the power supply connected to the other end of the auxiliary contact through the optocoupler driving unit connected in parallel with the first resistor R1 is also 5-110V DC (Vdc). This design is suitable for DC power supplies with a voltage range of 5V to 110V and can adapt to current requirements under different operating conditions.

[0062] In this embodiment, the optocoupler receiving unit includes an optical signal receiver, a third resistor R3, a fourth resistor R4, and a capacitor C1; the optocoupler receiving unit, through the combination of the optical signal receiver, the third resistor R3, the fourth resistor R4, and the capacitor C1, is used to receive and process the output signal of the optocoupler driving unit.

[0063] Specifically, in this embodiment, when the optocoupler driving unit outputs an optical signal, the optical signal receiver converts the optical signal into an electrical signal. The low-potential terminal of the optical signal receiver is grounded, and its output terminal is connected to one end of both the third resistor R3 and the fourth resistor R4. The other end of the third resistor R3 is connected to the positive terminal of the power supply, used to limit the current of the electrical signal output by the optical signal receiver, protecting the optical signal receiver from excessive current and ensuring its normal operation. The fourth resistor R4 is connected in series with capacitor C1, and the other end of capacitor C1 is grounded. The fourth resistor R4 acts as a voltage divider, dividing the electrical signal output by the optical signal receiver to a voltage level suitable for subsequent circuit processing. That is, the end of the third resistor R3 furthest from the positive terminal of the power supply is connected between the fourth resistor R4 and the optical signal receiver. The capacitor C1 and the fourth resistor R4 connected in series form an RC filter circuit, which smooths the electrical signal output by the optical signal receiver, filters out high-frequency noise and voltage fluctuations, and ensures the stability and accuracy of the output signal.

[0064] Furthermore, in the above embodiment, the positive terminal of the power supply connected to the other end of the third resistor R3 is a DC voltage of 3.3V+ or 5V+. The selection of the voltage level of the positive terminal of the power supply (such as 3.3V or 5V) depends on the operating voltage requirements of the optical signal receiver and subsequent circuits. This voltage selection ensures that the entire control circuit maintains a stable current and voltage environment during operation, further enhancing the reliability and anti-interference capability of the control circuit.

[0065] In this embodiment, the optical signal receiver and the optical signal transmitter form an optical coupler PQ1.

[0066] In this embodiment, when the output terminal of the optical signal receiver generates current, the third resistor R3 limits the current magnitude through its resistance characteristics to prevent the optical signal receiver from overloaded under high current, and at the same time protects the safe operation of the downstream connected circuit components. In this embodiment, it is used to protect the safe operation of the microcontroller.

[0067] Furthermore, the value of the third resistor R3 needs to be selected not only to ensure the current limiting function, but also to avoid excessively high resistance values ​​that could affect signal transmission efficiency.

[0068] Specifically, the fourth resistor R4, together with the optical signal receiver and the third resistor R3, forms a voltage divider circuit. Its function is to perform voltage division on the signal output from the optical signal receiver. Specifically, the voltage at the output of the optical signal receiver is reduced in amplitude through the voltage divider loop formed by the fourth resistor R4 and ground, making it compatible with the microcontroller's input voltage range. Furthermore, the value of the fourth resistor R4 needs to be designed based on the output characteristics of the optical signal receiver and the input voltage requirements of subsequent circuits, ensuring that the signal amplitude is neither too high (causing circuit damage) nor too low (affecting signal validity).

[0069] In the above embodiments, the optocoupler receiving unit can stably convert the working state of the auxiliary contact into a standard level signal output. The third resistor R3 effectively controls the current magnitude, preventing overcurrent that could cause component overheating or damage; the fourth resistor R4 forms a voltage divider network, ensuring that the signal amplitude remains stable within the acceptable range of subsequent circuits, suitable for signal detection requirements of various control circuits. Simultaneously, by rationally setting the resistance values ​​of the third resistor R3 and the fourth resistor R4, both circuit protection and signal quality are considered, further improving the reliability and adaptability of the optocoupler receiving unit, providing a stable and efficient signal output solution for the status feedback of the auxiliary contact.

[0070] In this embodiment, the optocoupler receiving unit is connected to the input terminal of the microcontroller to transmit the real-time operating status signal of the auxiliary contact. Specifically, when the auxiliary contact is closed, the optocoupler receiving unit outputs a low-level signal F1 to the microcontroller, feeding back the operating status of the auxiliary contact to the microcontroller and ensuring the real-time monitoring and reliability of the control circuit.

[0071] Specifically, in this embodiment, the end of the fourth resistor R4 furthest from the optical signal receiver is connected in series with the capacitor C1, and the other end of the capacitor C1 is grounded, forming an RC filter circuit, which can effectively remove high-frequency noise in the output signal of the optical signal receiver, smooth the output signal, and make the output signal more stable.

[0072] More specifically, the microcontroller is a single-chip microcomputer (MCU).

[0073] When the auxiliary contact closes, the optical signal receiver receives the optical signal emitted by the optical signal transmitter and converts it into an electrical signal. After processing by a voltage divider circuit and an RC filter circuit, a low-level signal F1 is output to the microcontroller. At this time, the low-level signal F1 (logic "0") indicates that the auxiliary contact has been successfully closed and the main contacts of the DC contactor are in the working state. The microcontroller uses this information to determine the state of the DC contactor and executes the corresponding control logic.

[0074] When the auxiliary contact is disconnected, the optical signal receiver no longer receives the optical signal, and the output level of the optocoupler receiving unit returns to the high-level signal F1 (logic "1"). After receiving the signal, the microcontroller can determine that the auxiliary contact has been disconnected, thereby monitoring the working status of the DC contactor and taking corresponding measures.

[0075] In the above embodiments, the RC filter circuit of the optocoupler receiving unit eliminates high-frequency interference in the signal, ensuring signal smoothness and stability. Simultaneously, the switching between the low-level signal F1 and the high-level signal enables the microcontroller to accurately monitor the state changes of the auxiliary contacts, meeting the requirements for high-precision control and real-time monitoring.

[0076] In this embodiment, when the coil is energized, the main contacts close and the auxiliary contacts also close. When the auxiliary contacts close, the optocoupler drive unit receives the current signal and sends the optical signal to the optical signal receiver through the optical signal transmitter. After receiving the optical signal, the optical signal receiver performs current limiting and voltage division on the output signal through the third resistor R3 and the fourth resistor R4, and then smooths the signal through the capacitor C1 to generate the corresponding level signal for subsequent circuit detection and use.

[0077] In this embodiment, the control device for the DC contactor has the control circuit of the DC contactor. The control device for the DC contactor is suitable for high-voltage DC scenarios, such as 1500Vdc or 600Vdc high-voltage power supply systems, and is widely used in energy storage systems, industrial automation equipment, and electric vehicles.

[0078] Specifically, in this embodiment, the control circuit of the DC contactor accurately detects the working status of the auxiliary contacts through a feedback circuit, and generates a stable level signal through an optocoupler receiving unit, which is then provided to the microcontroller for status monitoring and system control. In high-voltage scenarios, the DC contactor drives the opening and closing of the main contacts through a coil. The auxiliary contacts work in conjunction with the feedback circuit to ensure that the opening and closing status of the main contacts can be accurately fed back, thereby improving the stability and safety of the system.

[0079] In this embodiment, by setting the first resistor R1 to be connected in parallel with the optocoupler driving unit, the current through the auxiliary contact can be effectively increased, ensuring that the auxiliary contact can reliably engage in high voltage and high current scenarios, and avoiding the problem of unstable operation due to insufficient current.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A control circuit for a DC contactor, comprising a DC contactor and a feedback circuit connected in series with auxiliary contacts of the DC contactor, the feedback circuit being used to provide feedback on the on / off state of the main contacts through the on / off state of the auxiliary contacts; characterized in that, The feedback circuit includes an optocoupler driving unit, an optocoupler receiving unit, and a first resistor R1; the first resistor R1 is connected in parallel with the optocoupler driving unit.

2. The control circuit of the DC contactor according to claim 1, characterized in that, The resistance value of the first resistor R1 is less than or equal to a preset value; when the resistance value of the first resistor R1 is equal to the preset value, the current through the auxiliary contact is the minimum current required to make the auxiliary contact close. Preferably, the resistance value of the first resistor R1 is equal to a preset value.

3. The control circuit for the DC contactor according to claim 2, characterized in that, The first resistor R1 is a single resistor; or, the first resistor R1 is composed of multiple sub-shunt resistors, which are connected in series and / or in parallel. Preferably, the first resistor R1 is composed of multiple parallel sub-shunt resistors.

4. The control circuit of the DC contactor according to claim 3, characterized in that, The first resistor R1 is mounted on a heat sink substrate, which is used to dissipate the heat of the first resistor R1. Preferably, the heat dissipation substrate is an aluminum substrate; Preferably, a heat sink is provided on the heat dissipation substrate.

5. The control circuit for the DC contactor according to any one of claims 1 to 3, characterized in that, The optocoupler driving unit includes an optical signal transmitter and a second resistor R2 connected in series with the optical signal transmitter; the end of the optical signal transmitter away from the second resistor R2 is connected to the negative terminal of the power supply. One end of the first resistor R1 is connected between the auxiliary contact and the second resistor R2, and the other end of the first resistor R1 is connected between the optical signal transmitter and the negative terminal of the power supply.

6. The control circuit for the DC contactor according to claim 5, characterized in that, The resistance value of the first resistor R1 is less than the resistance value of the second resistor R2.

7. The control circuit for the DC contactor according to any one of claims 1 to 6, characterized in that, The DC contactor also includes a coil and main contacts. The A1 and A2 ends of the coil are connected to the positive and negative terminals of the external control circuit, respectively. One end of the auxiliary contact is connected to the positive terminal of the power supply, and the other end is connected to the negative terminal of the power supply through an optocoupler drive unit connected in parallel with the first resistor R1.

8. The control circuit for the DC contactor according to any one of claims 1 to 7, characterized in that, The optocoupler receiving unit is connected to the input terminal of the microcontroller. When the auxiliary contact is closed, the optocoupler receiving unit outputs a low-level signal F1 to the microcontroller.

9. The control circuit for the DC contactor according to any one of claims 1 to 8, characterized in that, The optocoupler receiving unit includes an optical signal receiver, a third resistor R3, a fourth resistor R4, and a capacitor C1; The low-potential end of the optical signal receiver is grounded, and the output end of the optical signal receiver is connected to one end of the third resistor R3 and one end of the fourth resistor R4, respectively. The other end of the third resistor R3 is connected to the positive terminal of the power supply, and the other end of the fourth resistor R4 is grounded through capacitor C1.

10. A control device for a DC contactor, comprising the control circuit of the DC contactor as described in any one of claims 1 to 9.

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