Contactor control system

Abstract

This invention provides a contactor control system that ensures a stable holding current for the contactor coil, simplifies the structure, and reduces costs. [Solution] The contactor control system comprises: a switch circuit (1) connected between one end (C+) of the contactor coil and the positive terminal (V+) of the power supply, adapted to be switched between an on state and an off state; a control circuit (2) that controls the switch circuit (1) to switch between an on state and an off state; a current detection circuit (3) connected to the other end (C-) of the contactor coil and used for real-time detection of the current flowing through the contactor coil; a DC / DC converter (4) whose feedback terminal FB is connected to the output terminal of the current detection circuit (3); and a diode D2 whose positive terminal is connected to the output terminal VDD_AJ of the DC / DC converter (4) and whose negative terminal is connected to one end (C+) of the contactor coil.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of Chinese Patent Application No. CN202411614158.8, filed with the China National Intellectual Property Administration on November 12, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a contactor control system.

Background Art

[0003] [[ID=…]]<00…>

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention is made to overcome or alleviate at least one aspect of the above - mentioned drawbacks.

Means for Solving the Problems

[0005] Notes: Some of the tags like ,

[0003] , etc. in the original seem to be incomplete or have incorrect formatting in the provided text. I've left them as they are in the translation with the assumption that they are part of a larger patent - specific tag system that might be corrected in the original context. Also, the ellipsis (...) added in the translation for the repeated - like tags is just to show the pattern of the incomplete tags in the original text.According to one aspect of the present invention, a contactor control system is provided. The contactor control system comprises a switch circuit connected between one end of a contactor coil and the positive terminal of a power supply and adapted to be switched between an on state and an off state; a control circuit for controlling the switch circuit to switch between an on state and an off state; a current detection circuit connected to the other end of the contactor coil and used for real-time detection of the current flowing through the contactor coil; a DC / DC converter, the DC / DC converter having a feedback terminal FB connected to the output terminal of the current detection circuit; and a diode D2, the diode D2 having its positive terminal connected to the output terminal VDD_AJ of the DC / DC converter and its negative terminal connected to one end of the contactor coil. During the contactor coil startup phase, the control circuit switches the switch circuit to the ON state to establish an electrical connection between one end of the contactor coil and the positive terminal of the power supply, and controls it to maintain the ON state for a predetermined time t. During the contactor coil holding phase, the control circuit controls it to switch the switch circuit to the Open state to disconnect the electrical connection between one end of the contactor coil and the positive terminal of the power supply.

[0006] According to an exemplary embodiment of the present invention, during the start-up phase of the contactor coil, the output voltage at the output terminal of the DC / DC converter is lower than the power supply voltage V1, and the diode D2 is used to prevent the power supply voltage V1 from being applied in reverse to the output terminal of the DC / DC converter.

[0007] According to another exemplary embodiment of the present invention, in the starting stage of the contactor coil, the switch circuit supplies power to the contactor coil via the power supply by connecting the positive terminal of the power supply to one end of the contactor coil, and the starting current I1 of the contactor coil is I1 = V1 / Rc It can be calculated according to the following formula: Here, V1 is the power supply voltage, and Rc is the resistance of the contactor coil.

[0008] According to another exemplary embodiment of the present invention, during the contactor coil holding stage, the switch circuit supplies power to the contactor coil via the output terminal of the DC / DC converter by interrupting the electrical connection between the positive terminal of the power supply and one end of the contactor coil.

[0009] According to another exemplary embodiment of the present invention, during the contactor coil holding phase, a current sensing circuit detects the holding current I2 flowing through the contactor coil in real time, and the DC / DC converter adjusts the output voltage of the DC / DC converter's output terminals based on the holding current I2 detected by the current sensing circuit until the holding current I2 detected by the current sensing circuit becomes equal to a predetermined holding current I.

[0010] According to another exemplary embodiment of the present invention, when the holding current I2 detected by the current detection circuit is greater than a predetermined holding current I, the DC / DC converter gradually lowers the output voltage until the holding current I2 detected by the current detection circuit becomes equal to the predetermined holding current I, and when the holding current I2 detected by the current detection circuit is less than a predetermined holding current I, the DC / DC converter gradually raises the output voltage until the holding current I2 detected by the current detection circuit becomes equal to the predetermined holding current I.

[0011] According to another exemplary embodiment of the present invention, the contactor control system is an LDO circuit, the input terminal of which is connected to the positive terminal of a power supply, and the output terminal of which is connected to the power supply terminal of the control circuit and the power supply terminal of the current sensing circuit, and further comprises an LDO circuit for supplying a stable power supply voltage to the control circuit and the current sensing circuit.

[0012] According to another exemplary embodiment of the present invention, the control circuit comprises a comparator U4, the output terminal of which is connected to the input terminal of a switch circuit; a resistor R3, one end of which is connected to the output terminal of an LDO circuit and the other end of which is connected to the inverting input of comparator U4; a capacitor C4, one end of which is connected to the other end of resistor R3 and the other end is grounded; a resistor R4, one end of which is connected to the output terminal of an LDO circuit and the other end of which is connected to the common-mode input of comparator U4; and a resistor R5, one end of which is connected to the other end of resistor R4 and the other end is grounded.

[0013] According to another exemplary embodiment of the present invention, the control circuit further comprises a capacitor C5, one end of which is connected to the power supply terminal of comparator U4 and the other end is grounded, and the output terminal of the LDO circuit is connected to the power supply terminal of comparator U4 and used to supply a stable power supply voltage to comparator U4.

[0014] According to another exemplary embodiment of the present invention, the switch circuit comprises an N-type MOS transistor Q2, the gate of which is connected to the output terminal of the control circuit and the source of which is grounded, and a P-type MOS transistor Q1, the gate of which is connected to the drain of which is connected to

[0015] According to another exemplary embodiment of the present invention, the switch circuit further comprises: a resistor R7, one end of which is connected to the source of a P-type MOS transistor Q1 and the other end of which is connected to the gate of a P-type MOS transistor Q1; a resistor R8, one end of which is connected to the output terminal of a comparator U4 and the other end of which is connected to the gate of an N-type MOS transistor Q2; and a resistor R9, one end of which is connected to the other end of which is connected to the gate of an N-type MOS transistor Q2 and the other end is grounded.

[0016] According to another exemplary embodiment of the present invention, the switch circuit further comprises a diode D1, the positive terminal of which is connected to the positive terminal of a power supply, and the negative terminal of which is connected to one end of a resistor R7 and the source of a P-type MOS transistor Q1.

[0017] According to another exemplary embodiment of the present invention, when the charging time of capacitor C4 has not reached a predetermined time t, the voltage drop across capacitor C4 is less than the voltage drop across resistor R5, the voltage at the common-mode input of comparator U4 is higher than the voltage at the inverting input of comparator U4, the output terminal of comparator U4 outputs a high level, simultaneously driving and conducting the N-type MOS transistor Q2 and the P-type MOS transistor Q1, thereby switching the switch circuit to the ON state.

[0018] According to another exemplary embodiment of the present invention, when the charging time of capacitor C4 reaches a predetermined time t, the voltage drop across capacitor C4 is greater than the voltage drop across resistor R5, the voltage at the common-mode input of comparator U4 is lower than the voltage at the inverting input of comparator U4, the output terminal of comparator U4 outputs a low level, simultaneously driving and shutting off the N-type MOS transistor Q2 and the P-type MOS transistor Q1, thereby switching the switch circuit to the off state.

[0019] According to another exemplary embodiment of the present invention, the current sensing circuit comprises a sampling resistor R, one end of which is used to connect to the other end of a contactor coil and the other end of which is grounded, and a current sensing chip U3, the positive input terminal VIN+ of which is connected to one end of the sampling resistor R and the negative input terminal VIN- of which is connected to the other end of the sampling resistor R. The output terminal of the current sensing chip U3 is connected to the feedback terminal FB of the DC / DC converter and is used to feed back the holding current I2 detected by the current sensing chip U3 to the feedback terminal FB of the DC / DC converter.

[0020] According to another exemplary embodiment of the present invention, the current sensing chip U3 collects the voltage drop V2 across the sampling resistor R via the positive input terminal VIN+ and the negative input terminal VIN-, and the holding current I2 detected by the current sensing chip U3 is I2 = V2 / R It can be calculated according to the following formula: Here, R is the resistance value of the sampling resistor R.

[0021] According to another exemplary embodiment of the present invention, the power supply terminal VCC of the current sensing chip U3 is connected to the output terminal of the LDO circuit, and the ground terminal GND and reference voltage terminal REF of the current sensing chip U3 are grounded.

[0022] According to another exemplary embodiment of the present invention, the current sensing circuit further comprises capacitors C8 and C9, one end of which is connected to the power supply terminal VCC of the current sensing chip U3, and the other end of which is connected to the ground terminal GND and the reference voltage terminal REF of the current sensing chip U3.

[0023] According to another exemplary embodiment of the present invention, the DC / DC converter is a DC / DC conversion chip U1, which has an input voltage pin VIN and an enable pin EN for connecting to the positive electrode of the power supply, and the power ground pin PGND and the analog ground pin AGND of the DC / DC conversion chip U1 are grounded. The output terminal Vout of the DC / DC conversion chip U1 is connected to the positive terminal of the diode D2, and the feedback terminal FB of the DC / DC conversion chip U1 is connected to the output terminal of the current detection chip U③.

[0024] According to another exemplary embodiment of the present invention, the DC / DC converter includes capacitors C1 and C2, one end of each of which is connected to the input voltage pin VIN of the DC / DC conversion chip U1, and the other end of each of which is grounded, and capacitors C3 and C6, one end of each of which is connected to the output terminal Vout of the DC / DC conversion chip U1, and the other end of each of which is grounded.

[0025] According to another exemplary embodiment of the present invention, the LDO circuit includes a low dropout linear regulator U2, the input terminal of the low dropout linear regulator U2 is used to connect to the positive electrode of the power supply, a capacitor C10, one end of the capacitor C10 is connected to the input terminal of the low dropout linear regulator U2, and the other end is grounded, and a capacitor C7, one end of the capacitor C7 is connected to the output terminal of the low voltage difference linear regulator U2, and the other end is grounded. The output terminal of the low dropout linear regulator U2 is connected to the input terminal of the control circuit, the power supply terminal of the comparator U④, and the power supply terminal VCC of the current detection chip U③, and is used to supply a stable ⑤V power supply voltage to the control circuit, the comparator U④, and the current detection chip U③.

[0026] In the foregoing exemplary embodiment according to the present invention, the output voltage of the DC / DC converter can be adjusted in real time based on the holding current of the contactor coil detected by the current detection circuit, thereby ensuring that the contactor coil has a stable holding current in the holding stage. According to the present invention, the structure of the contactor control system is simplified, and the cost of the contactor control system is reduced.

[0027] The above and other features of the present invention will become more apparent by describing its exemplary embodiments in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0028] [Figure 1] It is a functional block diagram of a contactor control system according to an exemplary embodiment of the present invention. <00001​​​​​​​​​​​​​​​​​​The contactor control system comprises a switch circuit connected between one end of the contactor coil and the positive terminal of the power supply, adapted to be switchable between an on state and an off state; a control circuit for controlling the switch circuit to switch between an on state and an off state; a current sensing circuit connected to the other end of the contactor coil and used for real-time detection of the current flowing through the contactor coil; a DC / DC converter, the DC / DC converter's feedback terminal FB being connected to the output terminal of the current sensing circuit; and a diode D2, the diode D2's positive terminal being connected to the DC / DC converter's output terminal VDD_AJ and the diode D2's negative terminal being used to connect to one end of the contactor coil. During the contactor coil startup phase, the control circuit switches the switch circuit to the on state and controls it to maintain the on state for a predetermined time t in order to make an electrical connection between one end of the contactor coil and the positive terminal of the power supply. During the contactor coil holding phase, the control circuit controls it to switch the switch circuit to the open state in order to disconnect the electrical connection between one end of the contactor coil and the positive terminal of the power supply.

[0032] Figure 1 shows a functional block diagram of a contactor control system according to an exemplary embodiment of the present invention. Figure 2 shows a circuit diagram of a contactor control system according to an exemplary embodiment of the present invention.

[0033] As shown in Figures 1 and 2, an exemplary embodiment of the present invention discloses a contactor control system. The contactor control system includes a switch circuit 1, a control circuit 2, a current detection circuit 3, a DC / DC converter 4, and a diode D2. The switch circuit 1 is used to connect one end C+ of the contactor coil 7 to the positive terminal V+ of the power supply 6 and is adapted to be switched between an on state and an off state. The control circuit 2 is used to control the switch circuit 1 to switch between an on state and an off state. The current detection circuit 3 is connected to the other end C- of the contactor coil 7 for real-time detection of the current flowing through the contactor coil 7. The feedback terminal FB of the DC / DC converter 4 is connected to the output terminal of the current detection circuit 3. The positive terminal of diode D2 is connected to the output terminal VDD_ADJ of the DC / DC converter 4, and the negative terminal of diode D2 is used to connect to one end C+ of the contactor coil 7.

[0034] As shown in Figures 1 and 2, in the illustrated embodiment, during the start-up phase of the contactor coil 7, the control circuit 2 switches the switch circuit 1 to the ON state and maintains the ON state for a predetermined time t in order to establish an electrical connection between one end C+ of the contactor coil 7 and the positive terminal V+ of the power supply 6. During the holding phase of the contactor coil 7, the control circuit 2 controls the switch circuit 1 to the OFF state in order to disconnect the electrical connection between one end C+ of the contactor coil 7 and the positive terminal V+ of the power supply 6.

[0035] As shown in Figures 1 and 2, in the illustrated embodiment, during the startup phase of the contactor coil 7, the output voltage at the output terminal of the DC / DC converter 4 is lower than the power supply voltage V1 of the power supply 6. Diode D2 is used to prevent the power supply voltage V1 from being applied in reverse to the output terminal of the DC / DC converter 4.

[0036] As shown in Figures 1 and 2, in the illustrated embodiment, during the startup phase of the contactor coil 7, the switch circuit 1 supplies power to the contactor coil 7 via the power supply 6 by connecting the positive terminal V+ of the power supply 6 to one end C+ of the contactor coil 7.

[0037] As shown in Figures 1 and 2, in the illustrated embodiment, the starting current I1 of the contactor coil 7 is I1 = V1 / Rc It can be calculated according to the following formula: Here, V1 is the power supply voltage of power supply 6, and Rc is the resistance of contactor coil 7.

[0038] As shown in Figures 1 and 2, in the illustrated embodiment, during the holding stage of the contactor coil 7, the switch circuit 1 supplies power to the contactor coil 7 via the output terminal of the DC / DC converter 4 by interrupting the electrical connection between the positive terminal V+ of the power supply 6 and one end C+ of the contactor coil 7.

[0039] As shown in Figures 1 and 2, in the illustrated embodiment, during the holding phase of the contactor coil 7, the current detection circuit 3 detects the holding current I2 flowing through the contactor coil 7 in real time. The DC / DC converter 4 adjusts its output voltage based on the holding current I2 detected by the current detection circuit 3 until the holding current I2 detected by the current detection circuit 3 becomes equal to a predetermined holding current I.

[0040] As shown in Figures 1 and 2, in the illustrated embodiment, when the holding current I2 detected by the current detection circuit 3 is greater than a predetermined holding current I, the DC / DC converter 4 gradually lowers the output voltage until the holding current I2 detected by the current detection circuit 3 becomes equal to the predetermined holding current I. When the holding current I2 detected by the current detection circuit 3 is less than a predetermined holding current I, the DC / DC converter 4 gradually raises the output voltage until the holding current I2 detected by the current detection circuit 3 becomes equal to the predetermined holding current I.

[0041] As shown in Figures 1 and 2, in the illustrated embodiment, the contactor control system also includes an LDO circuit 5. The input terminal of the LDO circuit 5 is connected to the positive terminal V+ of the power supply 6, and the output terminal of the LDO circuit 5 is connected to the power supply terminal of the control circuit 2 and the power supply terminal of the current detection circuit 3, and is used to supply a stable power supply voltage to the control circuit 2 and the current detection circuit 3.

[0042] As shown in Figures 1 and 2, in the illustrated embodiment, the control circuit 2 includes a comparator U4, a resistor R3, a capacitor C4, another resistor R4, and another resistor R5. The output terminal of comparator U4 is connected to the input terminal of switch circuit 1. One end of resistor R3 is connected to the output terminal of LDO circuit 5, and the other end of resistor R3 is connected to the inverting input of comparator U4. One end of capacitor C4 is connected to the other end of resistor R3, and the other end of capacitor C4 is grounded. One end of resistor R4 is connected to the output terminal of LDO circuit 5, and the other end of resistor R4 is connected to the common-mode input of comparator U4. One end of resistor R5 is connected to the other end of resistor R4, and the other end of resistor R5 is grounded.

[0043] As shown in Figures 1 and 2, in the illustrated embodiment, the control circuit 2 further includes a capacitor C5, one end of which is connected to the power supply terminal of comparator U4 and the other end of which is grounded. The output terminal of the LDO circuit 5 is connected to the power supply terminal of comparator U4 and is used to supply a stable power supply voltage to comparator U4.

[0044] As shown in Figures 1 and 2, in the illustrated embodiment, the switch circuit 1 includes an N-type MOS transistor Q2 and a P-type MOS transistor Q1. The gate of the N-type MOS transistor Q2 is connected to the output terminal of the control circuit 2, and the source of the N-type MOS transistor Q2 is grounded. The gate of the P-type MOS transistor Q1 is connected to the drain of the N-type MOS transistor Q2, the source of the P-type MOS transistor Q1 is used to connect to the positive terminal V+ of the power supply 6, and the drain of the P-type MOS transistor Q1 is used to connect to one end C+ of the contactor coil 7.

[0045] As shown in Figures 1 and 2, in the illustrated embodiment, the switch circuit 1 further includes resistors R7, R8, and R9. One end of resistor R7 is connected to the source of P-type MOS transistor Q1, and the other end of resistor R7 is connected to the gate of P-type MOS transistor Q1. One end of resistor R8 is connected to the output terminal of comparator U4, and the other end of resistor R8 is connected to the gate of N-type MOS transistor Q2. One end of resistor R9 is connected to the other end of resistor R8 and the gate of N-type MOS transistor Q2, and the other end of resistor R9 is grounded.

[0046] As shown in Figures 1 and 2, in the illustrated embodiment, the switch circuit 1 further includes a diode D1. The positive terminal of diode D1 is used to connect to the positive terminal V+ of the power supply 6, and the negative terminal of diode D1 is connected to one end of resistor R7 and the source of P-type MOS transistor Q1.

[0047] As shown in Figures 1 and 2, in the illustrated embodiment, when the charging time of capacitor C4 has not reached a predetermined time t, the voltage drop across capacitor C4 is smaller than the voltage drop across resistor R5. The voltage at the common-mode input of comparator U4 is higher than the voltage at the inverting input of comparator U4, and the output terminal of comparator U4 outputs a high level, simultaneously driving and conducting the N-type MOS transistor Q2 and the P-type MOS transistor Q1, thereby switching the switch circuit 1 to the ON state.

[0048] As shown in Figures 1 and 2, in the illustrated embodiment, when the charging time of capacitor C4 reaches a predetermined time t, the voltage drop across capacitor C4 is greater than the voltage drop across resistor R5. The voltage at the common-mode input of comparator U4 is lower than the voltage at the inverting input of comparator U4, and the output terminal of comparator U4 outputs a low level, simultaneously driving and shutting off the N-type MOS transistor Q2 and the P-type MOS transistor Q1, thereby switching the switch circuit 1 to the off state.

[0049] As shown in Figures 1 and 2, in the illustrated embodiment, the current detection circuit 3 includes a sampling resistor R and a current detection chip U3. One end of the sampling resistor R is used to connect to the other end C- of the contactor coil 7, and the other end of the sampling resistor R is grounded. The positive input terminal VIN+ of the current detection chip U3 is connected to one end of the sampling resistor R, and the negative input terminal VIN- of the current detection chip U3 is connected to the other end of the sampling resistor R. The output terminal of the current detection chip U3 is connected to the feedback terminal FB of the DC / DC converter 4 and is used to feed back the holding current I2 detected by the current detection chip U3 to the feedback terminal FB of the DC / DC converter 4.

[0050] As shown in Figures 1 and 2, in the illustrated embodiment, the current sensing chip U3 collects the voltage drop V2 across the sampling resistor R via the positive input terminal VIN+ and the negative input terminal VIN-. The holding current I2 detected by the current sensing chip U3 is I2 = V2 / R It can be calculated according to the following formula: Here, R is the resistance value of the sampling resistor R.

[0051] As shown in Figures 1 and 2, in the illustrated embodiment, the power supply terminal VCC of the current detection chip U3 is connected to the output terminal of the LDO circuit 5, and the ground terminal GND and reference voltage terminal REF of the current detection chip U3 are grounded.

[0052] As shown in Figures 1 and 2, in the illustrated embodiment, the current detection circuit 3 further includes capacitors C8 and C9. One end of capacitor C8 and one end of capacitor C9 are connected to the power terminal VCC of the current detection chip U3, and the other end of capacitor C8 and the other end of capacitor C9 are connected to the ground terminal GND and the reference voltage terminal REF of the current detection chip U3.

[0053] As shown in Figures 1 and 2, in the illustrated embodiment, the DC / DC converter 4 includes a DC / DC conversion chip U1. The input voltage pin VIN and enable pin EN of the DC / DC conversion chip U1 are used to connect to the positive terminal V+ of the power supply 6, and the power ground pin PGND and analog ground pin AGND of the DC / DC conversion chip U1 are grounded. The output terminal Vout of the DC / DC conversion chip U1 is connected to the positive terminal of diode D2, and the feedback terminal FB of the DC / DC conversion chip U1 is connected to the output terminal of the current sensing chip U3.

[0054] As shown in Figures 1 and 2, in the illustrated embodiment, the DC / DC converter 4 further includes capacitors C1 and C2, and capacitors C3 and C6. One end of capacitor C1 and one end of capacitor C2 are connected to the input voltage pin VIN of the DC / DC conversion chip U1, and the other end of capacitor C1 and the other end of capacitor C2 are grounded. One end of capacitor C3 and one end of capacitor C6 are connected to the output terminal Vout of the DC / DC conversion chip U1, and the other end of capacitor C3 and the other end of capacitor C6 are grounded.

[0055] As shown in Figures 1 and 2, in the illustrated embodiment, the LDO circuit 5 includes a low-dropout linear regulator U2, a capacitor C10, and a capacitor C7. The input terminal of the low-dropout linear regulator U2 is used to connect to the positive terminal V+ of the power supply 6. One end of the capacitor C10 is connected to the input terminal of the low-dropout linear regulator U2, and the other end of the capacitor C10 is grounded. One end of the capacitor C7 is connected to the output terminal of the low-dropout linear regulator U2, and the other end of the capacitor C7 is grounded. The output terminal of the low-dropout linear regulator U2 is connected to the input terminal of the control circuit 2, the power supply terminal of the comparator U4, and the power supply terminal VCC of the current sensing chip U3, supplying a stable 5V power supply voltage to the control circuit 2, the comparator U4, and the current sensing chip U3.

[0056] In this application, unless otherwise specified, "grounded" means "connected to the negative terminal V- of power supply 6".

[0057] Those skilled in the art will understand that the above embodiments are illustrative and not intended to be limiting. For example, many modifications to the above embodiments may be made by those skilled in the art, and various features described in different embodiments may be freely combined with one another without structural or principle contradiction.

[0058] While several exemplary embodiments have been illustrated and described, those skilled in the art will understand that many variations or modifications can be made to these embodiments without departing from the principles and spirit of the disclosure. The scope of the disclosure is defined in the claims and its equivalents.

[0059] In this specification, elements described in the singular and preceded by the words "a" or "an" should be understood not to exclude multiple such elements or steps unless otherwise expressly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be construed as excluding the existence of additional embodiments that similarly incorporate the described features. Furthermore, unless otherwise expressly stated to the contrary, embodiments that “compile” or “have” one or more elements having a particular characteristic may include additional such elements that do not possess that characteristic.

Claims

1. A switch circuit (1) is connected between one end (C+) of the contactor coil (7) and the positive terminal (V+) of the power supply (6), and is adapted to be switched between an on state and an off state. A control circuit (2) for controlling the switch circuit (1) to switch between the ON state and the OFF state, A current detection circuit (3) is connected to the other end (C-) of the contactor coil (7) and is used for real-time detection of the current flowing through the contactor coil (7), A DC / DC converter (4), wherein the feedback terminal FB of the DC / DC converter (4) is connected to the output terminal of the current detection circuit (3), Diode D2 is used to connect the positive terminal of diode D2 to the output terminal VDD_AJ of the DC / DC converter (4) and the negative terminal of diode D2 to one end (C+) of the contactor coil (7), and Equipped with, In the starting stage of the contactor coil (7), the control circuit (2) switches the switch circuit (1) to the ON state and controls it to maintain the ON state for a predetermined time t in order to make an electrical connection between one end (C+) of the contactor coil (7) and the positive terminal (V+) of the power supply (6). During the holding stage of the contactor coil (7), the control circuit (2) controls the switch circuit (1) to switch to the open state in order to interrupt the electrical connection between one end (C+) of the contactor coil (7) and the positive terminal (V+) of the power supply (6). Contactor control system.

2. The contactor control system according to claim 1, wherein, during the starting stage of the contactor coil (7), the output voltage at the output terminal of the DC / DC converter (4) is lower than the power supply voltage V1 of the power supply (6), and the diode D2 is used to prevent the power supply voltage V1 from being applied in reverse to the output terminal of the DC / DC converter (4).

3. During the startup phase of the contactor coil (7), the switch circuit (1) supplies power to the contactor coil (7) via the power supply (6) by connecting the positive terminal (V+) of the power supply (6) to one end (C+) of the contactor coil (7). The starting current I1 of the contactor coil (7) is I1 = V1 / Rc It can be calculated according to the following formula: The contactor control system according to claim 2, wherein V1 is the power supply voltage of the power supply (6) and Rc is the resistance of the contactor coil (7).

4. The contactor control system according to claim 1, wherein during the holding stage of the contactor coil (7), the switch circuit (1) supplies power to the contactor coil (7) via the output terminal of the DC / DC converter (4) by interrupting the electrical connection between the positive terminal (V+) of the power supply (6) and one end (C+) of the contactor coil (7).

5. In the holding stage of the contactor coil (7), the current detection circuit (3) detects the holding current I2 flowing through the contactor coil (7) in real time, and the DC / DC converter (4) adjusts the output voltage of the output terminal of the DC / DC converter (4) based on the holding current I2 detected by the current detection circuit (3) until the holding current I2 detected by the current detection circuit (3) becomes equal to a predetermined holding current I, the contactor control system according to claim 4.

6. When the holding current I2 detected by the current detection circuit (3) is greater than the predetermined holding current I, the DC / DC converter (4) gradually lowers the output voltage until the holding current I2 detected by the current detection circuit (3) becomes equal to the predetermined holding current I. The contactor control system according to claim 5, wherein when the holding current I2 detected by the current detection circuit (3) is smaller than the predetermined holding current I, the DC / DC converter (4) gradually increases the output voltage until the holding current I2 detected by the current detection circuit (3) becomes equal to the predetermined holding current I.

7. The contactor control system according to claim 1, further comprising an LDO circuit (5) whose input terminal is connected to the positive terminal (V+) of the power supply (6), and whose output terminal is connected to the power supply terminal of the control circuit (2) and the power supply terminal of the current detection circuit (3), for supplying a stable power supply voltage to the control circuit (2) and the current detection circuit (3).

8. The control circuit (2) is, Comparator U4, wherein the output terminal of the comparator U4 is connected to the input terminal of the switch circuit (1), A resistor R3, wherein one end of the resistor R3 is connected to the output terminal of the LDO circuit (5), and the other end of the resistor R3 is connected to the inverting input of the comparator U4, A capacitor C4, wherein one end of the capacitor C4 is connected to the other end of the resistor R3, and the other end is grounded. A resistor R4, wherein one end of the resistor R4 is connected to the output terminal of the LDO circuit (5), and the other end of the resistor R4 is connected to the common-mode input of the comparator U4, A resistor R5, wherein one end of the resistor R5 is connected to the other end of the resistor R4, and the other end is grounded. The contactor control system according to claim 7, comprising:

9. The control circuit (2) is, A capacitor C5 is further provided, wherein one end of the capacitor C5 is connected to the power terminal of the comparator U4 and the other end is grounded. The contactor control system according to claim 8, wherein the output terminal of the LDO circuit (5) is connected to the power supply terminal of the comparator U4 and is used to supply a stable power supply voltage to the comparator U4.

10. The aforementioned switch circuit (1) is An N-type MOS transistor Q2, wherein the gate of the N-type MOS transistor Q2 is connected to the output terminal of the control circuit (2), and the source of the N-type MOS transistor Q2 is grounded, A P-type MOS transistor Q1, wherein the gate of the P-type MOS transistor Q1 is connected to the drain of an N-type MOS transistor Q2, the source of the P-type MOS transistor Q1 is connected to the positive terminal (V+) of the power supply (6), and the drain of the P-type MOS transistor Q1 is connected to one end (C+) of the contactor coil (7). The contactor control system according to claim 8, comprising:

11. The aforementioned switch circuit (1) is A resistor R7, wherein one end of the resistor R7 is connected to the source of the P-type MOS transistor Q1, and the other end of the resistor R7 is connected to the gate of the P-type MOS transistor Q1. A resistor R8, wherein one end of the resistor R8 is connected to the output terminal of comparator U4, and the other end of the resistor R8 is connected to the gate of N-type MOS transistor Q2, A resistor R9, one end of which is connected to the other end of resistor R8 and the gate of N-type MOS transistor Q2, and the other end of which is grounded, and The contactor control system according to claim 10, further comprising:

12. The aforementioned switch circuit (1) is The contactor control system according to claim 11, further comprising a diode D1, the positive terminal of which is connected to the positive terminal (V+) of the power supply (6), and the negative terminal of which is connected to one end of resistor R7 and the source of P-type MOS transistor Q1.

13. The contactor control system according to claim 10, wherein when the charging time of the capacitor C4 has not reached the predetermined time t, the voltage drop across the capacitor C4 is less than the voltage drop across the resistor R5, the voltage at the common-mode input of the comparator U4 is higher than the voltage at the inverting input of the comparator U4, the output terminal of the comparator U4 outputs a high level, and simultaneously drives the N-type MOS transistor Q2 and the P-type MOS transistor Q1 to conduct, thereby switching the switch circuit (1) to the ON state.

14. The contactor control system according to claim 10, wherein when the charging time of the capacitor C4 reaches the predetermined time t, the voltage drop across the capacitor C4 is greater than the voltage drop across the resistor R5, the voltage at the common-mode input of the comparator U4 is lower than the voltage at the inverting input of the comparator U4, the output terminal of the comparator U4 outputs a low level, and simultaneously drives and disconnects the N-type MOS transistor Q2 and the P-type MOS transistor Q1, thereby switching the switch circuit (1) to the off state.

15. The current detection circuit (3) is A sampling resistor R, wherein one end of the sampling resistor R is used to connect to the other end (C-) of the contactor coil (7), and the other end is grounded. A current detection chip U3 has a positive input terminal VIN+ connected to one end of the sampling resistor R, and a negative input terminal VIN- connected to the other end of the sampling resistor R. Equipped with, The contactor control system according to claim 8, wherein the output terminal of the current detection chip U3 is connected to the feedback terminal FB of the DC / DC converter (4), and is used to feed back the holding current I2 detected by the current detection chip U3 to the feedback terminal FB of the DC / DC converter (4).

16. The current detection chip U3 collects the voltage drop V2 across the sampling resistor R via the positive input terminal VIN+ and the negative input terminal VIN-. The holding current I2 detected by the current detection chip U3 is I² = V² / R It can be calculated according to the following formula: Herein, R is the resistance value of the sampling resistor R, the contactor control system according to claim 15.

17. The contactor control system according to claim 15, wherein the power terminal VCC of the current detection chip U3 is connected to the output terminal of the LDO circuit (5), and the ground terminal GND and reference voltage terminal REF of the current detection chip U3 are grounded.

18. The contactor control system according to claim 17, wherein the current detection circuit (3) further comprises capacitors C8 and C9, one end of which is connected to the power terminal VCC of the current detection chip U3, and the other end of which is connected to the ground terminal GND and the reference voltage terminal REF of the current detection chip U3.

19. The DC / DC converter (4) is a DC / DC conversion chip U1, which has an input voltage pin VIN and an enable pin EN for connection to the positive terminal (V+) of the power supply (6), and the power ground pin PGND and analog ground pin AGND of the DC / DC conversion chip U1 are grounded. The contactor control system according to claim 15, wherein the output terminal Vout of the DC / DC conversion chip U1 is connected to the positive terminal of the diode D2, and the feedback terminal FB of the DC / DC conversion chip U1 is connected to the output terminal of the current detection chip U3.

20. The DC / DC converter (4) is Capacitors C1 and C2, each having one end connected to the input voltage pin VIN of the DC / DC conversion chip U1 and the other end connected to ground, Capacitors C3 and C6, each with one end connected to the output terminal Vout of the DC / DC conversion chip U1 and the other end connected to ground. The contactor control system according to claim 19, further comprising the above.

21. The LDO circuit (5) is A low-voltage drop linear regulator U2 is used to connect the input terminal of the low-voltage drop linear regulator U2 to the positive terminal (V+) of the power supply (6), A capacitor C10, wherein one end of the capacitor C10 is connected to the input terminal of the low-dropout linear regulator U2, and the other end is grounded. Capacitor C7, wherein one end of capacitor C7 is connected to the output terminal of the low voltage difference linear regulator U2 and the other end is grounded. Equipped with, The contactor control system according to claim 15, wherein the output terminal of the low-dropout linear regulator U2 is connected to the input terminal of the control circuit (2), the power terminal of the comparator U4, and the power terminal VCC of the current detection chip U3, and is for supplying a stable 5V power supply voltage to the control circuit (2), the comparator U4, and the current detection chip U3.

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