Relay coil starting control circuit

Abstract

The utility model discloses a relay coil starting control circuit, comprising an MCU, a coil driving circuit and a voltage sampling circuit, the coil driving circuit is connected between a coil and a power supply, the voltage sampling circuit is connected with the power supply, the MCU is connected with the coil driving circuit and the voltage sampling circuit, and the MCU is connected with the coil driving circuit and the voltage sampling circuit. And the MCU is used for acquiring pull-in voltage through the voltage sampling circuit and can perform on-off control on the coil driving circuit according to the pull-in voltage so as to control the connection or disconnection between the coil and the power supply. The relay coil starting control circuit can meet the requirement of stable pull-in voltage of a contactor, improves the reliability of a relay, and is simple in function and low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of relays, in particular to a relay coil starting control circuit. Background Art

[0002] With the popularity of new energy vehicles, combined with the use of battery packs, DC relays need to meet more new requirements for the quality and functional requirements of DC relay products, and hope to make in-depth innovations in technology. The pull-in voltage of the relay is one of the basic parameters of the relay's operation, and plays an important role in the normal operation and stability of the relay. The pull-in voltage of the relay refers to the relay's normal operation. When the voltage in the control circuit reaches or exceeds the pull-in voltage of the relay, the relay's contacts will close to realize the on-off of the circuit.

[0003] There are many types of DC relays on the market, which can be mainly divided into single coil and double coil according to the structure. When the external temperature of a single coil DC relay rises during use, the coil will change with the change of temperature, and the resistance of the coil will also change accordingly. Since the pull-in voltage of the relay is related to the resistance of the coil, the change of the resistance of the coil will directly cause the pull-in voltage of the relay to not remain at a voltage value, and it will fluctuate greatly with the change of the coil resistance, thereby reducing the reliability of the relay. Therefore, it is necessary to improve the existing technology to overcome the defects in the existing technology. Summary of the invention

[0004] The problem to be solved by the utility model is to provide a relay coil starting control circuit to overcome the defect that the pull-in voltage of the existing relay will have a large volt value fluctuation as the coil resistance changes, thereby reducing the reliability of the relay.

[0005] The utility model adopts a technical solution to solve its technical problems: providing a relay coil starting control circuit, comprising an MCU, a coil driving circuit and a voltage sampling circuit, wherein the coil driving circuit is connected between the coil and a power supply, the voltage sampling circuit is connected to the power supply, the MCU is connected to the coil driving circuit and the voltage sampling circuit, the MCU is used to obtain a pull-in voltage through the voltage sampling circuit, and can perform on-off control on the coil driving circuit according to the pull-in voltage, thereby controlling the coil to be connected or disconnected with the power supply.

[0006] As a further improvement of the present invention, the MCU is configured with a threshold voltage. When the pull-in voltage is greater than or equal to the threshold voltage, the MCU outputs a first control signal to turn on the coil drive circuit, thereby connecting the coil to the power supply; when the pull-in voltage is less than the threshold voltage, the MCU outputs a second control signal to turn off the coil drive circuit, thereby disconnecting the coil from the power supply.

[0007] As a further improvement of the present invention, the coil driving circuit includes a first MOS tube, a gate of the first MOS tube is connected to the MCU, a drain of the first MOS tube is directly or indirectly connected to the coil, and a source of the first MOS tube is grounded.

[0008] As a further improvement of the present invention, the coil driving circuit further includes a second MOS transistor, and the first MOS transistor is indirectly connected to the coil through the second MOS transistor;

[0009] The source of the second MOS tube is connected to the drain of the first MOS tube, the drain of the second MOS tube is connected to the coil, and the gate of the second MOS tube is connected to the power supply.

[0010] As a further improvement of the utility model, a switching diode and a third resistor are connected in series between the positive electrode of the power supply and the gate of the second MOS tube, a first voltage regulator diode, a third capacitor and a fourth resistor are connected in parallel between the gate and the source of the second MOS tube, a TVS tube is connected between the source and the drain of the second MOS tube, and a first Schottky diode is connected between the source of the second MOS tube and the positive electrode of the power supply.

[0011] As a further improvement of the present invention, the voltage sampling circuit includes a sampling resistor, and the sampling resistor is connected between the positive electrode of the power supply and the ground.

[0012] As a further improvement of the present invention, an A / D converter is configured in the MCU, and the MCU is provided with an ADC acquisition port and an I / O port, the ADC acquisition port is connected to the sampling resistor, and the I / O port is connected to the gate of the first MOS tube for outputting the first control signal and the second control signal.

[0013] As a further improvement of the utility model, it also includes a voltage stabilizing circuit, which is used to convert the voltage of the power supply into the working voltage of the MCU and provide it to the MCU.

[0014] As a further improvement of the present invention, the voltage stabilizing circuit includes an LDO voltage stabilizing chip, the input end of the LDO voltage stabilizing chip is connected to the positive electrode of the power supply, and the output end of the LDO voltage stabilizing chip is connected to the power supply end of the MCU.

[0015] As a further improvement of the present utility model, the voltage stabilizing circuit also includes a third MOS tube, the drain of the third MOS tube is connected to the positive electrode of the power supply, the source of the third MOS tube is connected to the input end of the LDO voltage stabilizing chip, and the gate of the third MOS tube is connected to the output end of the LDO voltage stabilizing chip.

[0016] The beneficial effects of the utility model are as follows: the utility model provides a relay coil starting control circuit, which uses the MCU to obtain the pull-in voltage through the voltage sampling circuit. When the pull-in voltage meets the set conditions, the coil driving circuit is controlled to energize the coil, effectively overcoming the defect that the pull-in voltage of the existing relay fluctuates greatly due to the change of the coil resistance value caused by the ambient temperature, meets the demand for stable pull-in voltage of the contactor, improves the reliability of the relay, and at the same time, by setting the threshold voltage parameters of the MCU, it can be conveniently adapted to different usage requirements, and has simple functions and low costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a block diagram of the relay coil start control circuit of the utility model;

[0018] Figure 2 It is a circuit schematic diagram of the relay coil starting control circuit of the utility model;

[0019] Figure 3 The figure is a flow chart of the relay coil starting control circuit of the utility model.

[0020] Combined with the accompanying drawings, the following description is given:

[0021] U1, MCU; U2, LDO voltage regulator chip; Q1A, second MOS tube; Q1B, first MOS tube; Q2, third MOS tube; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, sampling resistor; R6, sixth resistor; D1, first voltage regulator diode; D2, first Schottky diode; D3, second Schottky diode; D4, switching diode; D5, TVS tube; D6, second voltage regulator diode; C1, first capacitor; C2, second capacitor; C3, third capacitor; C4, fourth capacitor; C5, fifth capacitor; C6, sixth capacitor; C7, seventh capacitor. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0023] See also Figures 1 to 3 The utility model provides a relay coil start control circuit, including: MCUU1 (U1 is the label of MCU, the same below), a coil drive circuit and a voltage sampling circuit, the coil drive circuit is connected between the coil and the power supply, the voltage sampling circuit is connected to the power supply, MCUU1 is connected to the coil drive circuit and the voltage sampling circuit, MCUU1 is used to obtain the pull-in voltage through the voltage sampling circuit, and can control the on-off of the coil drive circuit according to the pull-in voltage, thereby controlling the connection or disconnection of the coil and the power supply. By adopting this technical solution, the utility model can collect the pull-in voltage through MCUU1 even if the resistance of the coil changes due to the ambient temperature. When the pull-in voltage meets the set conditions, the coil will be energized, which can meet the demand for stable pull-in voltage of the contactor and improve the reliability of the relay.

[0024] Among them, MCUU1 is configured with a threshold voltage. When MCUU1 detects that the pull-in voltage in the circuit is greater than or equal to the threshold voltage through a voltage sampling circuit, MCUU1 will output a first control signal, which can turn on the coil drive circuit, thereby connecting the coil to the power supply. When MCUU1 detects that the pull-in voltage in the circuit is less than the threshold voltage through a voltage sampling circuit, MCUU1 will output a second control signal, which can turn off the coil drive circuit, thereby disconnecting the coil from the power supply.

[0025] It should be noted that the threshold voltage of MCUU1 can be set according to the actual pull-in voltage required by the relay.

[0026] In the present invention, MCUU1 may be, but is not limited to, a PIC10F322 single-chip microcomputer, which is internally configured with an A / D converter, and the MCUU1 is provided with an ADC acquisition port and an I / O port. Figure 2 The RA2 port of U1 is connected to the voltage sampling circuit to continuously collect the pull-in voltage in the circuit. Figure 2 The RA0 / DAT port of U1 is connected to the coil driving circuit, and the I / O port is used to output the first control signal and the second control signal. Specifically, in this embodiment, the first control signal is a high level, and the second control signal is a low level.

[0027] See also Figure 2 The coil driving circuit includes a first MOS tube Q1B, which may be an NMOS tube. The gate of the first MOS tube Q1B is connected to the I / O port of the MCU through a sixth resistor R6. The drain of the first MOS tube Q1B is directly or indirectly connected to the coil, and the source of the first MOS tube Q1B is grounded. A second resistor R2 is connected between the gate of the first MOS tube Q1B and the ground.

[0028] When the I / O port of MCUU1 outputs the first control signal, i.e., a high level, the first MOS tube Q1B is turned on, thereby energizing the coil; when the I / O port of MCUU1 outputs the second control signal, i.e., a low level, the first MOS tube Q1B is turned off, thereby deenergizing the coil.

[0029] Furthermore, the coil driving circuit further includes a second MOS transistor Q1A, and the first MOS transistor Q1B is indirectly connected to the coil through the second MOS transistor Q1A. Specifically, the second MOS transistor Q1A may be an NMOS transistor, and the positive electrode of the power supply, i.e., port J1, is connected to the gate of the second MOS transistor Q1A through a series-connected switch diode D4 and a third resistor R3, and the drain of the second MOS transistor Q1A is connected to port J2, and the source of the second MOS transistor Q1A is connected to the drain of the first MOS transistor Q1B. The coil is connected to port J1 and port J2; port J3 is the negative electrode of the power supply, and a second Schottky diode D3 is connected between it and the ground.

[0030] When the I / O port of MCUU1 outputs the first control signal, i.e., a high level, the first MOS tube Q1B is turned on while the second MOS tube Q1A is also turned on. The power supply forms a path with the ground through the coil, the second MOS tube Q1A, the first MOS tube Q1B in sequence, and the coil is energized. The cooperation of the first MOS tube Q1B and the second MOS tube Q1A can play a role of dual control protection.

[0031] In addition, a first voltage stabilizing diode D1, a third capacitor C3 and a fourth resistor R4 are connected in parallel between the gate and source of the second MOS tube Q1A. The first voltage stabilizing diode D1 plays a role in protecting the gate of the second MOS tube Q1A, and the third capacitor C3 is used for filtering. A TVS tube is connected between the source and drain of the second MOS tube Q1A to protect the source and drain of the second MOS tube Q1A; a first Schottky diode D2 is connected between the source of the second MOS tube Q1A and the positive electrode of the power supply, i.e., the port J1, to suppress the reverse voltage.

[0032] Continue reading Figure 2 The voltage sampling circuit includes a first resistor R1 and a sampling resistor R5, and the first resistor R1 and the sampling resistor R5 are connected in series between the positive electrode of the power supply, that is, the port J1 and the ground. Among them, the purpose of using the first resistor R1 and the sampling resistor R5 to form a voltage sampling circuit is to achieve the acquisition of a wider range of voltages. The ADC acquisition port of MCUU1 is connected between the first resistor R1 and the sampling resistor R5, and is used to collect the voltage of the sampling resistor R5, that is, the pull-in voltage, and convert it into an AD value for comparison with the AD value of the set threshold voltage, and then control the I / O port to output the first control signal or the second control signal accordingly.

[0033] Furthermore, the relay coil start control circuit of the utility model also includes a voltage stabilizing circuit, which is used to convert the voltage of the power supply into the working voltage of MCUU1 and provide it to MCUU1, and at the same time serves as a reference voltage for AD acquisition.

[0034] Specifically, the voltage stabilizing circuit includes a third MOS tube Q2, an LDO voltage stabilizing chip U2 and its peripheral circuits. The model of the LDO voltage stabilizing chip U2 may be, but is not limited to, TLE4295GV50, which is provided with an input terminal, an output terminal and a GND terminal; the input terminal of the LDO voltage stabilizing chip U2 is connected to the source of the third MOS tube Q2, the output terminal of the LDO voltage stabilizing chip U2 is connected to the power supply terminal of the MCUU1, and the GND terminal of the LDO voltage stabilizing chip U2 is grounded; the drain of the third MOS tube Q2 is connected to the positive electrode of the power supply, i.e., the port J1, and the gate of the third MOS tube Q2 is connected to the output terminal of the LDO voltage stabilizing chip U2. Among them, the peripheral circuit of the LDO voltage stabilizing chip U2 includes a second capacitor C2 and a seventh capacitor C7 connected in parallel to the output terminal and the GND terminal, a fifth capacitor C5 connected between the drain and the source of the third MOS tube Q2, a first capacitor C1 and a second voltage stabilizing diode D6 connected in parallel between the input terminal and the GND terminal, and a fourth capacitor C4 connected in parallel to the first capacitor C1 and the fifth capacitor C5.

[0035] The utility model discloses a relay coil starting control circuit which utilizes MCUU1 to obtain the pull-in voltage through a voltage sampling circuit. When the pull-in voltage meets the set conditions, the coil driving circuit is controlled to energize the coil, which effectively overcomes the defect that the pull-in voltage of the existing relay fluctuates greatly due to the change of the coil resistance value caused by the ambient temperature, meets the demand for stable pull-in voltage of the contactor, and improves the reliability of the relay. At the same time, by setting the threshold voltage parameters of MCUU1, it can be conveniently adapted to different usage requirements, and has simple functions and low costs.

[0036] In the above description, many specific details are described to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited by the specific implementation disclosed above. At the same time, any person familiar with the technical field can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A relay coil starting control circuit, characterized in that: include: An MCU (U1), a coil driving circuit and a voltage sampling circuit, wherein the coil driving circuit is connected between the coil and a power supply, the voltage sampling circuit is connected to the power supply, the MCU (U1) is connected to the coil driving circuit and the voltage sampling circuit, and the MCU (U1) is used to obtain a pull-in voltage through the voltage sampling circuit, and can control the on-off of the coil driving circuit according to the pull-in voltage, thereby controlling the coil to be connected or disconnected with the power supply.

2. The relay coil starting control circuit according to claim 1, characterized in that: The MCU (U1) is configured with a threshold voltage. When the pull-in voltage is greater than or equal to the threshold voltage, the MCU (U1) outputs a first control signal to turn on the coil drive circuit, thereby connecting the coil to the power supply. When the pull-in voltage is less than the threshold voltage, the MCU (U1) outputs a second control signal to turn off the coil drive circuit, thereby disconnecting the coil from the power supply.

3. The relay coil starting control circuit according to claim 2, characterized in that: The coil driving circuit comprises a first MOS tube (Q1B), a gate of the first MOS tube (Q1B) is connected to the MCU (U1), a drain of the first MOS tube (Q1B) is directly or indirectly connected to the coil, and a source of the first MOS tube (Q1B) is grounded.

4. The relay coil starting control circuit according to claim 3, characterized in that: The coil driving circuit further comprises a second MOS transistor (Q1A), and the first MOS transistor (Q1B) is indirectly connected to the coil via the second MOS transistor (Q1A); The source of the second MOS tube (Q1A) is connected to the drain of the first MOS tube (Q1B), the drain of the second MOS tube (Q1A) is connected to the coil, and the gate of the second MOS tube (Q1A) is connected to the power supply.

5. The relay coil starting control circuit according to claim 4, characterized in that: A switching diode (D4) and a third resistor (R3) are connected in series between the positive electrode of the power supply and the gate of the second MOS tube (Q1A); a first voltage stabilizing diode (D1), a third capacitor (C3) and a fourth resistor (R4) are connected in parallel between the gate and the source of the second MOS tube (Q1A); a TVS tube (D5) is connected between the source and the drain of the second MOS tube (Q1A); and a first Schottky diode (D2) is connected between the source of the second MOS tube (Q1A) and the positive electrode of the power supply.

6. The relay coil starting control circuit according to claim 3, characterized in that: The voltage sampling circuit comprises a sampling resistor (R5), and the sampling resistor (R5) is connected between the positive electrode of the power supply and the ground.

7. The relay coil starting control circuit according to claim 6, characterized in that: The MCU (U1) is equipped with an A / D converter, and the MCU (U1) is provided with an ADC acquisition port and an I / O port, the ADC acquisition port is connected to the sampling resistor (R5), and the I / O port is connected to the gate of the first MOS tube (Q1B) for outputting the first control signal and the second control signal.

8. The relay coil starting control circuit according to claim 1, characterized in that: The device also includes a voltage stabilizing circuit, which is used to convert the voltage of the power supply into an operating voltage of the MCU (U1) and provide the operating voltage to the MCU (U1).

9. The relay coil starting control circuit according to claim 8, characterized in that: The voltage stabilizing circuit comprises an LDO voltage stabilizing chip (U2), an input end of the LDO voltage stabilizing chip (U2) is connected to the positive electrode of the power supply, and an output end of the LDO voltage stabilizing chip (U2) is connected to the power supply end of the MCU (U1).

10. The relay coil starting control circuit according to claim 9, characterized in that: The voltage stabilizing circuit further comprises a third MOS tube (Q2), the drain of the third MOS tube (Q2) being connected to the positive electrode of the power supply, the source of the third MOS tube (Q2) being connected to the input end of the LDO voltage stabilizing chip (U2), and the gate of the third MOS tube (Q2) being connected to the output end of the LDO voltage stabilizing chip (U2).

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