Contactor control system

Abstract

We provide a contactor control system. [Solution] The control circuit 2 is connected to the gate of the N-type MOS transistor Q1 in order to output a PWM wave to the gate of the N-type MOS transistor Q1. The current detection circuit 3 is connected to the drive circuit 1 in order to detect the holding current of the contactor coil in real time during the holding phase. The current detection circuit 3 is connected to the control circuit 2 in order to feed back the detected holding current to the control circuit 2, and the control circuit 2 adjusts the duty cycle of the PWM wave output by the control circuit 2 in real time based on the difference between the detected holding current and the predetermined holding current so that the holding current becomes equal to the predetermined holding current.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of Chinese Patent Application No. CN202411413633.5, filed with the China National Intellectual Property Administration on October 10, 2024, the entire disclosure of which is incorporated herein by reference.

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

Background Art

[0003] High - voltage contactors are important components in high - voltage power distribution. When starting a contactor, a relatively large starting current is required, and when holding the contactor, only a small holding current is needed. In the prior art, the main competitive advantage of high - voltage contactors is their small size, which meets the customer's demand for miniaturized applications. However, the starting current of the coil of a miniaturized high - voltage contactor is relatively high, usually requiring up to 3A at most. However, many customers have limited power supplies, and the supply current generally does not exceed 1.5A, and thus cannot meet the current requirements for coil startup. As a result, existing high - voltage contactors cannot be applied to many customers' products. In addition, in the prior art, the holding current of the contactor coil is affected by the power supply voltage and operating temperature, which may cause fluctuations in the holding current and affect the reliability of contactor operation. To ensure a stable holding current for the contactor coil, voltage compensation and temperature compensation are required in the prior - art contactor control system. However, the contactor control system based on this voltage compensation and temperature compensation has the problems of complex structure and high cost.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to overcome or mitigate at least one aspect of the above - mentioned drawbacks. [Means for solving the problem]

[0005] According to one aspect of the present invention, a contactor control system is provided. The contactor control system comprises a drive circuit, a control circuit, and a current detection circuit. The drive circuit includes a freewheeling diode D3, the negative terminal of which is used to electrically connect to the positive terminal of a power supply and one end of a contactor coil, and the positive terminal of which is used to electrically connect to the other end of a contactor coil; and an N-type MOS transistor Q1, the drain of which is connected to the positive terminal of the freewheeling diode D3, and the source of which is used to electrically connect to the negative terminal of a power supply. The control circuit is connected to the gate of the N-type MOS transistor Q1 to output a PWM wave to the gate of the N-type MOS transistor Q1. The current sensing circuit is connected to the drive circuit to detect the holding current I2 of the contactor coil in real time during the holding phase. The current sensing circuit is connected to the control circuit to feed back the detected holding current I2 to the control circuit, which adjusts the duty cycle D of the PWM wave output by the control circuit in real time based on the difference between the detected holding current I2 and the predetermined holding current I, so that the holding current I2 is equal to a predetermined holding current I.

[0006] According to an exemplary embodiment of the present invention, the holding current I2 of the contactor coil during the holding phase can be calculated according to the following formula: I2 = D * Vin / Rcoil Of these, Vin is the power supply voltage, and Rcoil is the resistance of the contactor coil.

[0007] According to another exemplary embodiment of the present invention, when the holding current I2 detected by the current sensing circuit is greater than a predetermined holding current I, the control circuit gradually decreases the duty cycle D of the PWM wave until the holding current I2 becomes equal to the predetermined holding current I, and when the holding current I2 detected by the current sensing circuit is less than a predetermined holding current I, the control circuit gradually increases the duty cycle D of the PWM wave until the holding current I2 becomes equal to the predetermined holding current I.

[0008] According to another exemplary embodiment of the present invention, the current sensing circuit includes a sampling resistor Rsense, one end of which is connected to the source of an N-type MOS transistor Q1 and the other end to ground, and a current sensing chip U3 having a positive input terminal VIN+ connected to one end of the sampling resistor Rsense and a negative input terminal VIN- connected to the other end of the sampling resistor Rsense. The control circuit is connected to the output terminal of the current sensing chip U3, and the current sensing chip U3 feeds back the detected holding current I2 to the control circuit.

[0009] According to another exemplary embodiment of the present invention, the current sensing chip U3 collects the voltage drop U across the sampling resistor Rsense via the positive input terminal VIN+ and the negative input terminal VIN-. The holding current I2 detected by the current sensing chip U3 can be calculated according to the following formula: I² = U / R Of these, U is the voltage drop across the sampling resistor Rsense, and R is the resistance value of the sampling resistor Rsense.

[0010] According to another exemplary embodiment of the present invention, the control circuit includes a microcontroller U1 having a timer connected to the gate of an N-type MOS transistor Q1, the timer of the microcontroller U1 being used to output a PWM wave to the gate of the N-type MOS transistor Q1.

[0011] According to another exemplary embodiment of the present invention, the control circuit further includes a resistor R1, one end of which is connected to a timer of a microcontroller U1 and the other end of which is connected to the gate of an N-type MOS transistor Q1, and a resistor R2, one end of which is connected to the gate of the N-type MOS transistor Q1 and the other end of resistor R1, and the other end of which is grounded.

[0012] According to another exemplary embodiment of the present invention, an analog-to-digital converter of the microcontroller U1 is connected to the output terminal of the current sensing chip U3 and is used to convert the analog current signal output by the current sensing chip U3 into a digital current signal.

[0013] According to another exemplary embodiment of the present invention, the contactor control system further comprises an LDO circuit having an input terminal for electrically connecting to a power supply to supply power to a microcontroller U1 and a current sensing chip U3, and an output terminal connected to the positive power supply terminal VDD of the microcontroller U1 and the power supply terminal VCC of the current sensing chip U3.

[0014] According to another exemplary embodiment of the present invention, the LDO circuit includes a low dropout linear regulator U2 having an input terminal connected to the positive terminal of a power supply, and an output terminal connected to the positive power supply terminal VDD of a microcontroller U1 and the power supply terminal VCC of a current sensing chip U3; capacitors C3 and C6, one end of which is connected to the input terminal of the low dropout linear regulator U2 and the other end is grounded; and capacitors C1 and C2, one end of which is connected to the output terminal of the low dropout linear regulator U2 and the other end is grounded.

[0015] According to another exemplary embodiment of the present invention, the power 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.

[0016] According to another exemplary embodiment of the present invention, the current sensing circuit further includes 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.

[0017] According to another exemplary embodiment of the present invention, the LDO circuit further includes a diode D2, the positive terminal of which is connected to the positive terminal of a power supply, and the negative terminal of which is connected to the input terminal of a low-dropout linear regulator U2.

[0018] According to another exemplary embodiment of the present invention, the drive circuit further includes 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 the negative terminal of a freewheeling diode D3.

[0019] According to another exemplary embodiment of the present invention, the duty cycle D of the PWM wave output to the gate of the N-type MOS transistor Q1 by the control circuit during the startup phase of the contactor coil is equal to 100%, and therefore the startup current I1 of the contactor coil during the startup phase is greater than or equal to a predetermined startup current.

[0020] According to another exemplary embodiment of the present invention, the starting current I1 of the contactor coil during the startup phase can be calculated according to the following formula: I1 = Vin / Rcoil Of these, Vin is the power supply voltage, and Rcoil is the resistance of the contactor coil.

[0021] According to another exemplary embodiment of the present invention, the duration of the PWM wave having a duty cycle D equal to 100% output to the gate of the N-type MOS transistor Q1 by the control circuit during the startup phase of the contactor coil is longer than a predetermined startup time.

[0022] According to another exemplary embodiment of the present invention, the predetermined startup current is 1.5 A or more, and the predetermined startup time is 65 milliseconds or more.

[0023] In the above exemplary embodiment according to the present invention, voltage compensation and temperature compensation are realized by using a feedback holding current, the structure of the contactor control system is simplified, the cost of the contactor control system is reduced, and it is ensured that the contactor coil has a stable holding current.

[0024] The above features of the present invention and other features will become clearer by explaining the exemplary embodiments of the present invention in detail while referring to the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] It is a functional block diagram of a contactor control system according to an exemplary embodiment of the present invention. [Figure 2] It is a circuit diagram of a contactor control system according to an exemplary embodiment of the present invention.

Modes for Carrying Out the Invention

[0026] Hereinafter, exemplary embodiments of the present disclosure will be described in detail while referring to the accompanying drawings. In the figures, the same reference numerals refer to the same elements. However, the present disclosure can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the present disclosure to those skilled in the art.

[0027] The following detailed description includes numerous specific details for illustrative purposes to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments can be carried out without these specific details. In other examples, well-known structures and apparatus are shown schematically for the sake of simplifying the drawings.

[0028] According to the general concept of the present invention, a contactor control system is provided. The contactor control system comprises a drive circuit, a control circuit, and a current detection circuit. The drive circuit includes a freewheeling diode D3, the negative terminal of which is used to electrically connect to the positive terminal of a power supply and one end of a contactor coil, and the positive terminal of which is used to electrically connect to the other end of a contactor coil, and an N-type MOS transistor Q1, the drain of which is connected to the positive terminal of the freewheeling diode D3, and the source of which is used to electrically connect to the negative terminal of a power supply. The control circuit is connected to the gate of the N-type MOS transistor Q1 to output a PWM wave to the gate of the N-type MOS transistor Q1. The current sensing circuit is connected to the drive circuit to detect the holding current I2 of the contactor coil in real time during the holding phase. The current sensing circuit is connected to the control circuit to feed back the detected holding current I2 to the control circuit, which adjusts the duty cycle D of the PWM wave output by the control circuit in real time based on the difference between the detected holding current I2 and the predetermined holding current I, so that the holding current I2 is equal to a predetermined holding current I.

[0029] 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.

[0030] As shown in Figures 1 and 2, an exemplary embodiment of the present invention discloses a contactor control system. The contactor control system comprises a drive circuit 1, a control circuit 2, and a current detection circuit 3. The drive circuit 1 includes a freewheeling diode D3 and an N-type MOS transistor Q1. The negative terminal of the freewheeling diode D3 is used to electrically connect to the positive terminal V+ of the power supply 6 and one end C+ of the contactor coil 5, and the positive terminal of the freewheeling diode D3 is used to electrically connect to the other end C- of the contactor coil 5. The drain of the N-type MOS transistor Q1 is connected to the positive terminal of the freewheeling diode D3, and the source of the N-type MOS transistor Q1 is used to electrically connect to the negative terminal V- of the power supply 6. The control circuit 2 is connected to the gate of the N-type MOS transistor Q1 to output a PWM wave to the gate of the N-type MOS transistor Q1. The current detection circuit 3 is connected to the drive circuit 1 and is used to detect the holding current I2 of the contactor coil 5 in real time during the holding phase.

[0031] As shown in Figures 1 and 2, in the illustrated embodiment, the current detection circuit 3 is connected to the control circuit 2 to feed back the detected holding current I2 to the control circuit 2. The control circuit 2 adjusts the duty cycle D of the PWM wave output by the control circuit 2 in real time based on the difference between the detected holding current I2 and the predetermined holding current I, so that the holding current I2 is equal to a predetermined holding current I.

[0032] As shown in Figures 1 and 2, in the illustrated embodiment, the holding current I2 of the contactor coil 5 during the holding phase can be calculated according to the following formula: I2 = D * Vin / Rcoil Of these, Vin is the power supply voltage of power supply 6, and Rcoil is the resistance of contactor coil 5.

[0033] 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 control circuit 2 gradually decreases the duty cycle D of the PWM wave until the holding current I2 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 control circuit 2 gradually increases the duty cycle D of the PWM wave until the holding current I2 becomes equal to the predetermined holding current I.

[0034] As shown in Figures 1 and 2, in the illustrated embodiment, the current detection circuit 3 includes a sampling resistor Rsense and a current detection chip U3. One end of the sampling resistor Rsense is connected to the source of an N-type MOS transistor Q1, and the other end of the sampling resistor Rsense is grounded (i.e., electrically connected to the negative terminal V- of the power supply 6). The positive input terminal VIN+ of the current detection chip U3 is connected to one end of the sampling resistor Rsense, and the negative input terminal VIN- of the current detection chip U3 is connected to the other end of the sampling resistor Rsense. The control circuit 2 is connected to the output terminal of the current detection chip U3, and the current detection chip U3 feeds back the detected holding current I2 to the control circuit 2.

[0035] As shown in Figures 1 and 2, in the illustrated embodiment, the current sensing chip U3 collects the voltage drop U across the sampling resistor Rsense via the positive input terminal VIN+ and the negative input terminal VIN-. The holding current I2 detected by the current sensing chip U3 can be calculated according to the following formula: I² = U / R Of these, U is the voltage drop across the sampling resistor Rsense, and R is the resistance value of the sampling resistor Rsense.

[0036] As shown in Figures 1 and 2, in the illustrated embodiment, the control circuit 2 includes a microcontroller U1, and the timer of the microcontroller U1 is connected to the gate of an N-type MOS transistor Q1. The timer of the microcontroller U1 is used to output a PWM wave to the gate of the N-type MOS transistor Q1.

[0037] As shown in Figures 1 and 2, in the illustrated embodiment, the control circuit 2 further includes resistors R1 and R2. One end of resistor R1 is connected to the timer of the microcontroller U1, and the other end of resistor R1 is connected to the gate of the N-type MOS transistor Q1. One end of resistor R2 is connected to the gate of the N-type MOS transistor Q1 and the other end of resistor R1, and the other end of resistor R2 is grounded.

[0038] As shown in Figures 1 and 2, in the illustrated embodiment, the analog-to-digital converter (ADC) of the microcontroller U1 is connected to the output terminal of the current sensing chip U3 and is used to convert the analog current signal output by the current sensing chip U3 into a digital current signal.

[0039] As shown in Figures 1 and 2, in the illustrated embodiment, the contactor control system also includes an LDO circuit 4. The input terminal of the LDO circuit 4 is used to electrically connect to a power supply 6, and the output terminal of the LDO circuit 4 is connected to the positive power supply terminal VDD of the microcontroller U1 and the power supply terminal VCC of the current sensing chip U3 to supply power to the microcontroller U1 and the current sensing chip U3 with a supply voltage of +5V.

[0040] As shown in Figures 1 and 2, in the illustrated embodiment, the LDO circuit 4 includes a low-dropout linear regulator U2 and capacitors C3, C6, C1, and C2. The input terminal of the low-dropout linear regulator U2 is connected to the positive terminal of the power supply 6, and the output terminal of the low-dropout linear regulator U2 is connected to the positive power supply terminal VDD of the microcontroller U1 and the power supply terminal VCC of the current sensing chip U3. Capacitors C3 and C6 are connected in parallel. One end of capacitors C3 and C6 is connected to the input terminal of the low-dropout linear regulator U2, and the other end of capacitors C3 and C6 is grounded. Capacitors C1 and C2 are connected in parallel. One end of capacitors C1 and C2 is connected to the output terminal of the low-dropout linear regulator U2, and the other end of capacitors C1 and C2 is grounded.

[0041] As shown in Figures 1 and 2, in the illustrated embodiment, the power terminal VCC of the current detection chip U3 is connected to the output terminal of the LDO circuit 4, and the ground terminal GND and reference voltage terminal REF of the current detection chip U3 are grounded.

[0042] As shown in Figures 1 and 2, in the illustrated embodiment, the current detection circuit 3 also includes capacitors C8 and C9. Capacitors C8 and C9 are connected in parallel. One end of capacitors C8 and C9 is connected to the power supply terminal VCC of the current detection chip U3, and the other end of capacitors C8 and C9 is connected to the ground terminal GND and the reference voltage terminal REF of the current detection chip U3.

[0043] As shown in Figures 1 and 2, in the illustrated embodiment, the LDO circuit 4 also includes a diode D2. The positive terminal of diode D2 is connected to the positive terminal of power supply 6, and the negative terminal of diode D2 is connected to the input terminal of low-dropout linear regulator U2.

[0044] As shown in Figures 1 and 2, in the illustrated embodiment, the drive circuit 1 further includes a diode D1. The positive terminal of diode D1 is connected to the positive terminal of power supply 6, and the negative terminal of diode D1 is connected to the negative terminal of freewheel diode D3.

[0045] As shown in Figures 1 and 2, in the illustrated embodiment, the duty cycle D of the PWM wave output to the gate of the N-type MOS transistor Q1 by the control circuit 2 during the startup phase of the contactor coil 5 is equal to 100%, and therefore the startup current I1 of the contactor coil 5 during the startup phase is greater than or equal to a predetermined startup current.

[0046] As shown in Figures 1 and 2, in the illustrated embodiment, the starting current I1 of the contactor coil 5 during the startup phase can be calculated according to the following formula: I1 = Vin / Rcoil Of these, Vin is the power supply voltage of power supply 6, and Rcoil is the resistance of contactor coil 5.

[0047] As shown in Figures 1 and 2, in the illustrated embodiment, the duration of the PWM wave having a duty cycle D equal to 100%, which is output to the gate of the N-type MOS transistor Q1 by the control circuit 2 during the startup phase of the contactor coil 5, is equal to or greater than a predetermined startup time.

[0048] As shown in Figures 1 and 2, in exemplary embodiments of the present invention, the predetermined starting current is 1.5A or more, for example, the predetermined starting current may be equal to 3A. The predetermined starting time is 65 milliseconds or more, for example, the predetermined starting time may be 100 milliseconds.

[0049] Figure 2 is merely an illustrative circuit diagram of the present invention, and the numerical values ​​of each electronic component are illustrative only and can be adjusted according to the actual situation. Furthermore, the circuit diagram for implementing the functional block diagram shown in Figure 1 is not limited to the circuit diagram shown in Figure 2. In the circuit diagram shown in Figure 2, unless otherwise specified, grounding usually refers to connecting the negative terminal V- of power supply 6.

[0050] Those skilled in the art should understand that the embodiments described above are illustrative and not limiting. For example, those skilled in the art can make many modifications to the embodiments described above without structural or principle contradictions, and can freely combine the various features described in different embodiments.

[0051] While several exemplary embodiments have been illustrated and described, it will be understood by those skilled in the art that various modifications or changes can be made to these embodiments without departing from the principles and spirit of this disclosure. The scope of this disclosure is defined in the claims and its equivalents.

[0052] When used herein, elements described in the singular form and preceded by the words "a" or "an" should be understood not to exclude the plural forms of such elements or steps unless it is explicitly stated that such exclusion is excluded. Furthermore, references to "one embodiment" of the present invention are not intended to be construed as excluding the existence of additional embodiments that likewise incorporate the described features. Moreover, unless it is expressly stated otherwise, 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 contactor control system, - A freewheeling diode D3, the negative terminal of which is used to electrically connect to the positive terminal (V+) of the power supply (6) and one end (C+) of the contactor coil (5), and the positive terminal of which is used to electrically connect to the other end (C-) of the contactor coil (5), and An N-type MOS transistor Q1, wherein the drain of the N-type MOS transistor Q1 is connected to the positive terminal of the freewheeling diode D3, and the source of the N-type MOS transistor Q1 is used to electrically connect to the negative terminal (V-) of the power supply (6). A drive circuit (1) including, - In order to output a PWM wave to the gate of the N-type MOS transistor Q1, a control circuit (2) is connected to the gate of the N-type MOS transistor Q1, - In order to detect the holding current I2 of the contactor coil (5) during the holding phase in real time, a current detection circuit (3) is connected to the drive circuit (1) and Equipped with, The current detection circuit (3) is connected to the control circuit (2) to feed back the detected holding current I2 to the control circuit (2), and the control circuit (2) adjusts the duty cycle D of the PWM wave output by the control circuit (2) in real time based on the difference between the detected holding current I2 and the predetermined holding current I, so that the holding current I2 becomes equal to a predetermined holding current I, in a contactor control system.

2. The holding current I2 of the contactor coil (5) during the holding stage can be calculated according to the following formula: I2=D*Vin / Rcoil The contactor control system according to claim 1, wherein Vin is the power supply voltage of the power supply (6) and Rcoil is the resistance of the contactor coil (5).

3. When the holding current I2 detected by the current detection circuit (3) is greater than the predetermined holding current I, the control circuit (2) gradually reduces the duty cycle D of the PWM wave until the holding current I2 becomes equal to the predetermined holding current I. The contactor control system according to claim 2, wherein when the holding current I2 detected by the current detection circuit (3) is smaller than the predetermined holding current I, the control circuit (2) gradually increases the duty cycle D of the PWM wave until the holding current I2 becomes equal to the predetermined holding current I.

4. The current detection circuit (3) is A sampling resistor Rsense, wherein one end of the sampling resistor Rsense is connected to the source of the N-type MOS transistor Q1, and the other end is grounded. A current detection chip U3 having a positive input terminal VIN+ connected to one end of the sampling resistor Rsense and a negative input terminal VIN- connected to the other end of the sampling resistor Rsense. Includes, The contactor control system according to claim 1, wherein the control circuit (2) is connected to the output terminal of the current detection chip U3, and the current detection chip U3 feeds back the detected holding current I2 to the control circuit (2).

5. The current detection chip U3 collects the voltage drop U across the sampling resistor Rsense via the positive input terminal VIN+ and the negative input terminal VIN-. The holding current I2 detected by the current detection chip U3 can be calculated according to the following formula: I² = U / R The contactor control system according to claim 4, wherein U is the voltage drop across the sampling resistor Rsense, and R is the resistance value of the sampling resistor Rsense.

6. The control circuit (2) includes a microcontroller U1 having a timer connected to the gate of the N-type MOS transistor Q1. The contactor control system according to claim 4, wherein the timer of the microcontroller U1 is used to output the PWM wave to the gate of the N-type MOS transistor Q1.

7. The control circuit (2) is, A resistor R1, wherein one end of the resistor R1 is connected to the timer of the microcontroller U1, and the other end is connected to the gate of the N-type MOS transistor Q1, A resistor R2, one end of which is connected to the gate of an N-type MOS transistor Q1 and the other end of which is connected to ground, and the other end of which is connected to ground. The contactor control system according to claim 6, further comprising:

8. The contactor control system according to claim 6, wherein the analog-to-digital converter (ADC) of the microcontroller U1 is connected to the output terminal of the current detection chip U3 and is used to convert the analog current signal output by the current detection chip U3 into a digital current signal.

9. The contactor control system according to claim 6, further comprising an LDO circuit (4), the LDO circuit (4) having an input terminal for electrically connecting to the power supply (6) to supply power to the microcontroller U1 and the current detection chip U3, and an output terminal connected to the positive power supply terminal VDD of the microcontroller U1 and the power supply terminal VCC of the current detection chip U3.

10. The LDO circuit (4) is A low-dropout linear regulator U2, having an input terminal connected to the positive terminal of the power supply (6), and an output terminal connected to the positive power supply terminal VDD of the microcontroller U1 and the power supply terminal VCC of the current detection chip U3, Capacitors C3 and C6, wherein one end of capacitors C3 and C6 is connected to the input terminal of the low-dropout linear regulator U2 and the other end is grounded, Capacitors C1 and C2, where one end of capacitors C1 and C2 is connected to the output terminal of the low-dropout linear regulator U2 and the other end is grounded. The contactor control system according to claim 9, including the following:

11. The contactor control system according to claim 9, wherein the power supply terminal VCC of the current detection chip U3 is connected to the output terminal of the LDO circuit (4), and the ground terminal GND and reference voltage terminal REF of the current detection chip U3 are grounded.

12. The current detection circuit (3) is The contactor control system according to claim 11, further comprising 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.

13. The LDO circuit (4) is The contactor control system according to claim 10, further comprising a diode D2, the positive terminal of which is connected to the positive terminal of the power supply (6), and the negative terminal of which is connected to the input terminal of the low-dropout linear regulator U2.

14. The aforementioned drive circuit (1) is The contactor control system according to claim 1, further comprising diode D1, wherein the positive terminal of diode D1 is connected to the positive terminal of the power supply (6), and the negative terminal of diode D1 is connected to the negative terminal of the freewheel diode D3.

15. The contactor control system according to any one of claims 1 to 14, wherein the duty cycle D of the PWM wave output to the gate of the N-type MOS transistor Q1 by the control circuit (2) during the startup phase of the contactor coil (5) is equal to 100%, and therefore the startup current I1 of the contactor coil (5) during the startup phase is greater than or equal to a predetermined startup current.

16. The starting current I1 of the contactor coil (5) during the startup phase can be calculated according to the following formula: I1=Vin / Rcoil The contactor control system according to claim 15, wherein Vin is the power supply voltage of the power supply (6) and Rcoil is the resistance of the contactor coil (5).

17. The contactor control system according to claim 15, wherein the duration of the PWM wave having a duty cycle D equal to 100%, which is output to the gate of the N-type MOS transistor Q1 by the control circuit (2) during the startup phase of the contactor coil (5), is equal to or greater than a predetermined startup time.

18. The contactor control system according to claim 17, wherein the predetermined starting current is 1.5 A or more, and the predetermined starting time is 65 milliseconds or more.

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