An integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor

Abstract

The present invention relates to an integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor, which includes an integrated drive circuit and a magnetic flux closed-loop control system. The integrated drive circuit includes a rectifier bridge, a filter capacitor, an integrated chip U 1、 U 2, driving the coil of the permanent magnet contactor and multiple capacitors and resistors; the rectifier bridge and the filter capacitor rectify the AC input voltage into a stable DC U 1、 U 2 chips form a full-bridge circuit; the magnetic flux closed-loop control system adopts a constant magnetic flux closed-loop control during the starting process of the permanent magnet contactor to minimize the operating power and automatically demagnetize, so as to save energy and suppress contact bounce; during the breaking process, a constant zero magnetic flux control is adopted to make the electromagnetic flux completely cancel the permanent magnetic flux at all times, so as to improve the opening speed and further improve the opening and closing performance of the permanent magnet switch. This system is beneficial to simplifying the hardware control circuit of the monostable permanent magnet contactor and improving the operation reliability and opening and closing performance of the monostable permanent magnet contactor.

Description

Technical Field

[0001] The present invention belongs to the field of switch electrical appliance control, and particularly relates to an integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor. Background Art

[0002] A contactor is a control electrical appliance suitable for remotely and frequently connecting and disconnecting AC and DC main circuits and large-capacity control circuits. Traditional electromagnetic contactors are widely used in low-voltage electrical systems, and the manufacturing technology and application market are very mature. However, during its operation, it usually generates relatively large noise, and the coil needs to be energized for a long time to maintain the suction state, resulting in easy burning of the coil due to temperature rise, and high energy consumption during long-term operation.

[0003] The biggest difference between a monostable permanent magnet contactor and a traditional electromagnetic contactor is that after closing, the coil does not need to be energized, and the permanent magnet realizes the function of maintaining the closing position, which is not affected by the input power supply, and the maintaining reliability is improved. Compared with electromagnetic contactors, there is no noise and no energy consumption during maintenance, fundamentally solving the problems of easy burning of the coil due to heat generation and high energy consumption during long-term power-on existing in traditional electromagnetic contactors, and conforming to the development direction of low carbon and energy saving.

[0004] When a monostable permanent magnet contactor performs closing and opening operations, an external control circuit needs to provide positive and negative currents to the operating mechanism coil. Therefore, the advantages and disadvantages of the hardware control circuit and the software control scheme directly affect the performance of the entire permanent magnet contactor. Most traditional intelligent control circuits for permanent magnet contactors are implemented using discrete components, with a large number of components, which affects the reliability of the permanent magnet contactor control circuit and greatly increases the cost, restricting its engineering application. Summary of the Invention

[0005] The purpose of the present invention is to provide an integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor, which is beneficial to simplifying the hardware control circuit of the monostable permanent magnet contactor and improving the operation reliability and closing and opening performance of the monostable permanent magnet contactor.

[0006] To achieve the above object, the technical solution adopted by the present invention is: an integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor, including an integrated drive circuit and a magnetic flux closed-loop control system. The integrated drive circuit includes a rectifier bridge B1, a filter capacitor C1, integrated chips U1 and U2, a permanent magnet contactor coil Coil1, capacitors C2, C3, C4, C5, and resistors R1, R2, R3, R4, R5, R6, R7, R8, R9. The rectifier bridge B1 and the filter capacitor C1 rectify the AC input voltage into a stable DC voltage. The U1 and U2 chips form a full-bridge circuit. C2, C3 and C4, C5 are the self-bias capacitors of the internal integrated switching tubes of U1 and U2 respectively, providing dynamic self-power supply voltages for the internal upper and lower tubes. R3, R4 and R5, R6 are the current-limiting resistors of the upper and lower tubes of U1 and U2 respectively, providing a hardware-adjustable self-locking current-limiting threshold for the chips. R2 and R7 are current detection resistors, used to detect the currents flowing through the drain electrodes of the lower tubes of U1 and U2 respectively. R8 and R9 form a resistor voltage-dividing circuit, which is used to reflect the voltage across the coil Coil1 through corresponding conversion. R1 is the system bus input voltage detection resistor. The 3-pin of the U1 chip is connected to the input voltage bus through R1 to monitor the over-voltage and under-voltage of the system in real time. In addition, fault information including over-voltage, under-voltage, over-current, and over-temperature is sent to the system MCU through the 6-pin of the chip. The unique ID information is set for each chip through different connection methods of the 9-pin, which is used to quickly locate the faulty chip and the type of fault.

[0007] During the starting process of the permanent magnet contactor, the magnetic flux closed-loop control system adopts constant magnetic flux closed-loop control to minimize the operating power and automatically demagnetize, so as to save energy and suppress contact bounce. During the breaking process, it adopts constant zero magnetic flux control to make the electromagnetic flux completely cancel the permanent magnetic flux at all times, so as to improve the breaking speed and further improve the switching performance of the permanent magnet switch.

[0008] Further, the magnetic flux closed-loop control system detects the coil current i of the permanent magnet contactor through the 7-pins of U1 and U2 coil , detects the coil voltage u through the voltage-dividing resistors R8 and R9 coil , and calculates the magnetic flux of the magnetic circuit according to the coil current i coil and the coil voltage u coil according to the formula (1):

[0009] ψ coil = ∫(u coil - i coil R coil )dt (1)

[0010] In the formula: ψ coil is the magnetic flux of the magnetic circuit, u coil is the coil voltage, i coil is the coil current, and R coil is the coil resistance.

[0011] Four MOSFET switches S1, S2, S3, and S4 inside two chips U1 and U2 form a full-bridge control circuit. The MOSFET drive signals of the upper and lower bridge arms are strictly complementary and a dead zone is inserted to prevent shoot-through. Four circuit states are defined according to the voltage polarity across the coil and the coil current direction: When S1 and S4 are conducting simultaneously and S2 and S3 are complementarily turned off, the rectified and filtered positive voltage is applied across the coil, causing the coil to be rapidly magnetized in the positive direction. Define the circuit state at this time as the +1 state; When S1 and S4 are turned off simultaneously and S2 and S3 are complementarily conducting, the negative capacitor voltage is applied across the coil, forcing the coil to rapidly demagnetize or be magnetized in the negative direction. Define the circuit state at this time as the -1 state; When only S4 is conducting and the coil current passes through the freewheeling diode D2 of S2 and S4 for positive freewheeling, the voltage across the coil is close to 0V. Define the circuit state at this time as 0 + state; When only S2 is conducting and the coil current passes through the freewheeling diode D4 of S4 and S2 for negative freewheeling, the voltage across the coil is also close to 0V. Define the circuit state at this time as 0 - state; In the two circuit states of 0+ state and 0- state, the coil current decreases slowly and the magnetic circuit demagnetizes slowly.

[0012] Furthermore, the flux linkage closed-loop control system is adjusted by using a hysteresis control method, and the flux linkage closed-loop control is realized as follows: By comparing and calculating the flux linkage value ψ coil with the reference flux linkage value ψ ref to obtain the flux linkage error Δψ, that is: Δψ = ψ coil - ψ ref , according to the flux linkage error Δψ and the hysteresis width ε, automatically select the appropriate circuit state and convert it into the drive state of the corresponding switch tube according to the switch table. The specific conversion is as follows:

[0013] When Δψ < 0, turn on the switch tubes S1 and S4, turn off the switch tubes S2 and S3, and select the +1 state circuit to rapidly magnetize the coil in the positive direction, so that the magnetic flux linkage ψ coil of the magnetic circuit rapidly reaches the set reference flux linkage ψ ref ; When 0 ≤ Δψ ≤ ε, automatically select the two circuit states of 0 + and 0 - according to the coil current direction. When the coil passes through a positive current, turn on the switch tube S4, turn off the switch tubes S1, S2, and S3, and make the coil current flow in positive freewheeling. When the coil passes through a negative current, turn on the switch tube S2, turn off the switch tubes S1, S3, and S4, and make the coil current flow in negative freewheeling. Through 0 + and 0 -Two circuit states cause the coil current in the forward or reverse direction to decrease slowly, thereby causing the coil magnetic circuit to demagnetize slowly; when Δψ>ε, turn on the switching tubes S2 and S3, turn off the switching tubes S1 and S4, and select the -1 state circuit to quickly demagnetize the coil or perform negative excitation.

[0014] Furthermore, under the action of the flux linkage hysteresis loop, optimize the control of the operation process of the monostable permanent magnet contactor: set the flux linkage reference value as a constant value during the starting process. As the air gap between the moving and static iron cores decreases, automatically adjust the magnitude and direction of the excitation current so that the total flux linkage composed of the electromagnetic flux linkage and the permanent magnet flux linkage is dynamically stable at the reference value, and the contactor starts with a constant flux linkage; during the stable holding process, turn off the four internal switching tubes, and the contactor is stably held in the attracted state by the permanent magnet force; during the breaking process, set the flux linkage reference value to 0. As the air gap between the moving and static iron cores increases, automatically adjust the magnitude of the demagnetization current so that the total flux linkage composed of the electromagnetic flux linkage and the permanent magnet flux linkage is always 0, and the contactor completes the breaking at the fastest speed, thereby realizing the flux linkage closed-loop control during the starting and breaking processes of the monostable permanent magnet contactor.

[0015] Furthermore, during the constant flux linkage starting and breaking processes of the monostable permanent magnet contactor, when the coil current exceeds the current limiting thresholds set by resistors R3, R4 and R5, R6, the integrated chip can perform hardware self-locking current limiting on the switching tubes, thereby protecting the drive circuit from damage and serving as the final hardware overcurrent protection; on the basis of the constant flux linkage starting and breaking of the permanent magnet contactor, further perform per-cycle current limiting control on the coil current. The specific control method is as follows: output the current limiting threshold i max , the coil current i coil and the current limiting threshold i max are connected to the internal PWM module of the MCU through the internal comparator of the MCU. When the coil current i coil is greater than the set current limiting threshold i max , output a complementary turn-off signal to the PWM module through the comparator, so that the switching tube is turned off for one PWM cycle until the coil current i coil is less than the current limiting threshold i max , the PWM cycle will be reopened, and the switching tube performs flux linkage closed-loop control according to the above hysteresis loop control method. Perform software-programmable per-cycle current limiting on the basis of the flux linkage closed-loop control to control the maximum value of the coil current, so as to realize the reliable operation of the permanent magnet contactor during the flux linkage closed-loop control process.

[0016] Furthermore, the integrated chips U1 and U2 are both BRD1267C integrated half-bridge chips, and they include the following pins:

[0017] Pin 1 is the HD pin, which is electrically connected to the drain of the internal integrated high-side MOSFET. It is also the input terminal of the self-powered circuit for the internal high-side and low-side MOSFETs and is connected to the DC input voltage HV+ terminal after rectification and filtering.

[0018] Pin 2 is the BPH pin, which is connected to the bypass capacitors C2 and C4 of the gate drivers of the high-side MOSFETs of U1 and U2, providing self-powered voltage for the high-side operation.

[0019] Pin 3 is the SM pin, which is the self-configuring system monitoring input terminal. If this pin is connected to the system input voltage bus through a resistor, it will automatically detect system overvoltage and undervoltage faults. If it is connected to the system ground through a thermistor, it will automatically detect system overtemperature faults.

[0020] Pin 4 is the INH pin, which is the input terminal for high-side MOSFET gate drive control and is connected to the output pins of system MCU PWM2 (U1) and PWM3 (U2).

[0021] Pin 5 is the INL pin, which is the input terminal for low-side MOSFET gate drive control and is connected to the output pins of system MCU PWM1 (U1) and PWM4 (U2).

[0022] Pin 6 is the FAULT pin, which is the integrated chip fault communication pin and is connected to the system MCU I / O pin to provide system fault information.

[0023] Pin 7 is the IPH pin, which is grounded through small-signal resistors R2 and R7 to provide the drain current information i - 、i + ;

[0024] Pin 8 is the BPL pin, which is connected to the bypass capacitors C3 and C5 of the gate drivers of the low-side MOSFETs of U1 and U2, providing self-powered voltage for the low-side operation.

[0025] Pin 9 is the ID pin, which configures unique ID information for each chip through different connection methods.

[0026] Pin 10 is the SG pin, which is the connection point for the small-signal pin of the low-side controller and the system MCU ground reference.

[0027] Pin 11 is the XL pin, which is grounded through resistors R4 and R6 to set the hardware current limit threshold of the low-side MOSFETs of U1 and U2.

[0028] Pin 12 is the LS pin, which is electrically connected to the source of the internal integrated low-side MOSFET.

[0029] Pin 13 is the HB pin, which is connected to the source of the upper MOSFET and the drain of the lower MOSFET, and is connected to both ends of the contactor coil Coil1;

[0030] Pin 14 is the XH pin, which is connected to the half-bridge output through resistors R3 and R5, and is used to set the hardware current limit threshold of the upper MOSFETs of U1 and U2.

[0031] Furthermore, the flux closed-loop control system constructs a voltage calculation module through Equation (1) to convert the voltage u across the filter capacitor C1 C1 into the voltage u across the contactor coil coil :

[0032]

[0033] In the formula: u coil is the voltage across the contactor coil, A represents the polarity of the voltage across the coil, R8 and R9 are the resistance values of the voltage dividing resistors, ΔT is the PWM period, and T on is the switch conduction time;

[0034] When a positive current flows through the contactor coil, the i output from the IPH pin of U2 + is positive; the i output from the IPH pin of U1 - is 0; when a negative current flows through, the i output from the IPH pin of U1 - is positive, and the i output from the IPH pin of U2 + is 0; compare i + and i - according to Equation (2) to determine the value of b, that is, to judge the direction of the coil current;

[0035]

[0036] After determining the value of b, construct a current calculation module according to Equation (3) to convert the currents i output from the IPH pins of U1 and U2 - and i + into the contactor coil current:

[0037] i coil = b * i b * g (3)

[0038] In the formula: i coil is the contactor coil current value, b represents the direction of the coil current, i b is the current output from the selected IPH pin; g is the gain coefficient, which is related to the resistance values of R2 and R7;

[0039] Then construct a flux calculation module according to Equation (4) to convert the coil voltage, current, and resistance into the magnetic flux of the magnetic circuit:

[0040] ψ coil = ∫(u coil - i coil R coil )dt (4)

[0041] Where: ψ coil is the magnetic flux linkage of the magnetic circuit, u coil is the coil voltage, i coil is the coil current, R coil is the coil resistance;

[0042] Four MOSFET switches S1, S2, S3, and S4 inside two integrated chips U1 and U2 form a full - bridge control circuit. The MOSFET drive signals of the upper and lower bridge arms are strictly complementary and a dead zone is inserted to prevent shoot - through. Six circuit states are defined according to the voltage polarity applied across the coil and the direction of the coil current: When S1 and S4 are conducting simultaneously and S2 and S3 are complementarily off, a positive voltage is applied across the coil, causing the positive coil current to rise rapidly. This circuit state is defined as the +1 + state; When S1, S2, S3, and S4 are all off and the positive coil current free - wheels through diodes D2 and D3, a negative coil voltage is applied across the coil, causing the positive current to drop rapidly. This circuit state is defined as the -1 + state; When only S4 is conducting and the positive coil current free - wheels through D2 and S4, the coil terminal voltage is close to 0V, enabling the positive coil current to drop slowly. This circuit state is defined as 0 + state;

[0043] When S1, S2, S3, and S4 are all off and the negative coil current free - wheels through D1 and D4, a positive coil voltage is applied across the coil, causing the absolute value of the negative current to decrease rapidly. This circuit state is defined as the +1 - state; When S2 and S3 are conducting simultaneously and S1 and S4 are complementarily off, a negative voltage is applied across the coil, causing the absolute value of the negative coil current to increase rapidly. This circuit state is defined as the -1 - state; When only S2 is conducting and the negative coil current free - wheels through D4 and S2, the coil terminal voltage is close to 0V, causing the absolute value of the negative current to decrease slowly. This circuit state is defined as 0 - state;

[0044] The six circuit states are uniformly written in the form of A b , where A represents the coil voltage polarity and b represents the coil current direction. By selecting the corresponding circuit state A b , the change direction and change speed of the coil current or magnetic flux linkage are controlled.

[0045] Furthermore, a magnetic flux linkage hysteresis controller is constructed. By comparing ψ coilWith ψ ref Obtain Δψ, determine the current direction according to the input b value, and then operate according to the following logical relationship:

[0046] When i coil > 0, select the upper half of the hysteresis control: when Δψ <0, select (80% + 1 + , 20% 0 + ) circuit to make the magnetic flux rise rapidly; when 0 <Δψ <ε, select (80% 0 + , 20% 0 + ) circuit to make the magnetic flux drop slowly; when Δψ > ε, select (80% - 1 + , 20% 0 + ) circuit to make the magnetic flux drop rapidly;

[0047] When i coil ≤ 0, select the lower half of the hysteresis control: when Δψ < - ε, select (80% + 1 - , 20% 0 - ) circuit to make the magnetic flux rise rapidly; when - ε <Δψ <0, select (80% 0 - , 20% 0 - ) circuit to make the magnetic flux rise slowly; when Δψ > 0, select (80% - 1 - , 20% 0 - ) circuit to make the magnetic flux drop rapidly;

[0048] Then convert the circuit state into the drive signals of S1 to S4; insert the 20% 0 + or 0 - state in each hysteresis control cycle to take into account the chip dynamic self - power supply and current detection functions; obtain the A value according to the selected circuit state and return A to the voltage calculation module to calculate the coil voltage.

[0049] Furthermore, under the action of the magnetic flux hysteresis, optimize the control of the operation process of the monostable permanent - magnet contactor: set the magnetic flux reference value as a constant value during the starting process. As the air gap between the moving and static iron cores decreases, automatically adjust the magnitude and direction of the exciting current so that the total magnetic flux composed of the electromagnetic magnetic flux and the permanent - magnet magnetic flux is dynamically stable at the reference value, and the contactor starts with a constant magnetic flux; turn off the four internal switching tubes during the stable holding process, and the contactor is stably held in the attracted state by the permanent - magnet force; set the magnetic flux reference value as 0 during the breaking process. As the air gap between the moving and static iron cores increases, automatically adjust the magnitude of the demagnetizing current so that the total magnetic flux composed of the electromagnetic magnetic flux and the permanent - magnet magnetic flux is always 0, and the contactor completes the breaking at the fastest speed, thus realizing the magnetic - flux closed - loop control of the starting and breaking processes of the monostable permanent - magnet contactor.

[0050] Further, during the constant magnetic flux starting and breaking processes of the monostable permanent magnet contactor, when the coil current exceeds the current limiting thresholds set by resistors R3, R4 and R5, R6, the integrated chip can perform hardware self-locking current limiting on the switching tube, thereby protecting the drive circuit from damage and serving as the final hardware overcurrent protection; on the basis of the constant magnetic flux starting and breaking of the permanent magnet contactor, the coil current is further controlled by current limiting on a per-cycle basis. The specific control method is as follows: the current limiting threshold i max is output through the programmable DAC, the coil current i coil and the current limiting threshold i max are connected to the internal PWM module of the MCU through the internal comparator of the MCU. When the coil current i coil is greater than the set current limiting threshold i max , a complementary turn-off signal is output to the PWM module through the comparator, causing the switching tube to close for one PWM cycle until the coil current i coil is less than the current limiting threshold i max , at which point the PWM cycle will reopen, and the switching tube performs magnetic flux closed-loop control according to the above-mentioned hysteresis control method. On the basis of the magnetic flux closed-loop control, per-cycle current limiting that can be software-programmed is performed to control the maximum value of the coil current, so as to achieve reliable operation of the permanent magnet contactor during the magnetic flux closed-loop control process.

[0051] Compared with the prior art, the present invention has the following beneficial effects: Aiming at the problems of poor operation reliability and high cost of the intelligent control module of the monostable permanent magnet contactor, an integrated magnetic flux closed-loop control system for the monostable permanent magnet contactor is proposed. This system ingeniously applies the integrated chip to the drive control of the monostable permanent magnet contactor, greatly improving the integration degree of the intelligent control circuit, thereby improving the overall reliability of the permanent magnet contactor and reducing the hardware cost. The internal switching tubes of the integrated chip are all driven in a self-powered manner without an external auxiliary power supply; at the same time, the chip can provide accurate real-time current information without constructing an external current detection circuit, further simplifying the hardware control circuit and reducing the cost of intelligent control. This system solves the defect of a large number of discrete components in the traditional circuit and further improves the operation reliability of the permanent magnet contactor. On this basis, a magnetic flux closed-loop control strategy is adopted to optimize the working process of the permanent magnet switch, achieving the purpose of suppressing closing bounce and increasing the opening speed, and improving the closing and opening performance of the permanent magnet contactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is the system schematic diagram of Embodiment 1 of the present invention;

[0053] Figure 2 is the schematic diagram of four circuit states in Embodiment 1 of the present invention;

[0054] Figure 3It is the schematic diagram of the flux linkage closed-loop control in the first embodiment of the present invention;

[0055] Figure 4 It is the system schematic diagram of the second embodiment of the present invention;

[0056] Figure 5 It is the schematic diagram of six circuit states in the second embodiment of the present invention;

[0057] Figure 6 It is the schematic diagram of the flux linkage hysteresis controller in the second embodiment of the present invention. Specific embodiments

[0058] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0059] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0060] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] Such as Figure 1As shown in the figure, this embodiment provides an integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor, including an integrated drive circuit and a magnetic flux closed-loop control system. The integrated drive circuit includes a rectifier bridge B1, a filter capacitor C1, integrated chips U1 and U2, a permanent magnet contactor coil Coil1, capacitors C2, C3, C4, C5, and resistors R1, R2, R3, R4, R5, R6, R7, R8, R9. The external pins of U1 and U2 are 1 - 14. The rectifier bridge B1 and the filter capacitor C1 rectify the AC input voltage into a stable DC voltage, and the U1 and U2 chips form a full-bridge circuit; C2, C3 and C4, C5 are the self-bias capacitors of the internal integrated switching tubes of U1 and U2 respectively, providing dynamic self-power supply voltages for the internal upper and lower tubes; R3, R4 and R5, R6 are the current-limiting resistors for the upper and lower tubes of U1 and U2 respectively, providing a hardware-adjustable self-locking current-limiting threshold for the chips; R2 and R7 are current detection resistors, used to detect the currents flowing through the drain electrodes of the lower tubes of U1 and U2 respectively; R8 and R9 form a resistor voltage division circuit, which can be used to reflect the voltage across the coil Coil1 through corresponding conversion; R1 is the system bus input voltage detection resistor, and the 3-pin of the U1 chip is connected to the input voltage bus through R1 to monitor the over-voltage and under-voltage of the system in real time. In addition, the fault information including over-voltage, under-voltage, over-current, and over-temperature is sent to the system MCU through the 6-pin of the chip; the unique ID information is set for each chip through different connection methods of the 9-pin, which is used to quickly locate the faulty chip and the type of fault.

[0062] The integrated chips U1 and U2 are existing off-the-shelf chips, and the function definitions of their pins (1 - 14) are as follows:

[0063] Pin 1: It is electrically connected to the drain of the upper MOSFET integrated inside the chip, and is also the input end of the self-power supply circuit of the internal upper and lower MOSFETs.

[0064] Pin 2: This pin is connected to the bypass capacitor of the upper MOSFET gate driver, providing a self-power supply voltage for the upper tube to work.

[0065] Pin 3: This pin is the self-configuration system monitoring input end. If this pin is connected to the system input voltage bus through a resistor, it will automatically detect the over-voltage and under-voltage faults of the system. If it is connected to the system ground through a thermistor, it will automatically detect the over-temperature fault of the system.

[0066] Pin 4: This pin is the input end of the upper MOSFET gate drive control, connected to the PWM output pin of the system MCU.

[0067] Pin 5: This pin is the input end of the lower MOSFET gate drive control, connected to the PWM output pin of the system MCU.

[0068] Pin 6: This pin is the communication pin for the integrated chip failure, connected to the system MCU I / O pin to provide system fault information.

[0069] Pin 7: This pin is grounded through a small-signal resistor to provide the drain current information of the lower MOSFET.

[0070] Pin 8: This pin is connected to the bypass capacitor of the lower MOSFET gate driver to provide the self-powered voltage for the operation of the lower MOSFET.

[0071] Pin 9: This pin configures unique ID information for each chip through different connection methods.

[0072] Pin 10: This pin is the connection point of the small-signal pin of the lower tube controller and the ground reference of the system MCU.

[0073] Pin 11: This pin is grounded through a resistor to set the hardware current limiting threshold of the lower MOSFET.

[0074] Pin 12: This pin is electrically connected to the source of the lower MOSFET integrated inside the chip.

[0075] Pin 13: This pin connects the source of the upper MOSFET and the drain of the lower MOSFET.

[0076] Pin 14: This pin is connected to the half-bridge output through a resistor to set the hardware current limiting threshold of the upper MOSFET.

[0077] During the starting process of the permanent magnet contactor, the flux closed-loop control system adopts constant flux closed-loop control to minimize the operating power and automatically weaken the magnetic field for energy conservation and suppression of contact bounce; during the breaking process, it adopts constant zero flux control to make the electromagnetic flux completely cancel the permanent magnetic flux at all times to improve the breaking speed, and thus improve the switching performance of the permanent magnet switch.

[0078] The working principle of the flux closed-loop control system is as follows:

[0079] Detect the coil current i of the permanent magnet contactor through the 7th pins of U1 and U2 coil , detect the coil voltage u through the voltage dividing resistors R8 and R9 coil , the coil current i coil and the coil voltage u coil Calculate the magnetic flux of the magnetic circuit according to the following formula:

[0080] ψ coil =∫(u coil -i coil R coil )dt

[0081] Where: ψ coil is the magnetic flux of the magnetic circuit, ucoil is the coil voltage, i coil is the coil current, R coil is the coil resistance.

[0082] As Figure 2 shown, the 4 MOSFET switches S1, S2, S3, and S4 inside the two chips U1 and U2 form a full-bridge control circuit. The MOSFET drive signals of the upper and lower bridge arms are strictly complementary and a dead zone is inserted to prevent shoot-through. Four circuit states are defined according to the voltage polarity applied across the coil and the direction of the coil current: When S1 and S4 are conducting simultaneously and S2 and S3 are complementarily turned off, the rectified and filtered positive voltage is applied across the coil, causing the coil to be quickly magnetized in the positive direction. Define the circuit state at this time as the +1 state; when S1 and S4 are turned off simultaneously and S2 and S3 are complementarily conducting, the negative capacitor voltage is applied across the coil, forcing the coil to quickly demagnetize or be magnetized in the negative direction. Define the circuit state at this time as the -1 state; when only S4 is conducting and the coil current passes through the freewheeling diode D2 of S2 and S4 for positive freewheeling, the voltage across the coil is close to 0V. Define the circuit state at this time as the 0+ state; when only S2 is conducting and the coil current passes through the freewheeling diode D4 of S4 and S2 for negative freewheeling, the voltage across the coil is also close to 0V. Define the circuit state at this time as the 0- state; in the two circuit states of 0+ state and 0- state, the coil current decreases slowly and the magnetic circuit demagnetizes slowly.

[0083] The magnetic flux closed-loop control system is adjusted by using the hysteresis control method. As Figure 3 shown, the specific principle of the magnetic flux closed-loop control is as follows: By comparing and calculating the magnetic flux value ψ c o il and the reference magnetic flux value ψ ref to obtain the magnetic flux error Δψ, that is: Δψ = ψ coil - ψ ref , according to the magnetic flux error Δψ and the hysteresis width ε, automatically select the appropriate circuit state and convert it into the drive state of the corresponding switch tube according to the switch table. The specific conversion is as follows:

[0084] When Δψ < 0, turn on the switch tubes S1 and S4, turn off the switch tubes S2 and S3, and select the +1 state circuit to quickly magnetize the coil in the positive direction, so that the magnetic flux ψ coil of the magnetic circuit quickly reaches the set reference magnetic flux ψ refWhen \(0\leq\Delta\psi\leq\varepsilon\), two circuit states, \(0+\) and \(0-\), are automatically selected according to the coil current direction. When the coil has a positive current flowing through it, switch tube S4 is turned on, and switch tubes S1, S2, and S3 are turned off, enabling the coil current to flow in a positive freewheeling manner. When the coil has a negative current flowing through it, switch tube S2 is turned on, and switch tubes S1, S3, and S4 are turned off, enabling the coil current to flow in a negative freewheeling manner. Through the two circuit states of \(0+\) and \(0-\), the positive or negative coil current decreases slowly, thereby causing the coil magnetic circuit to demagnetize slowly. When \(\Delta\psi>\varepsilon\), switch tubes S2 and S3 are turned on, and switch tubes S1 and S4 are turned off, selecting the -1 state circuit to quickly demagnetize the coil or negatively magnetize it.

[0085] In another embodiment of the present invention, both the integrated chips U1 and U2 are BRD1267C integrated half-bridge chips, which include the following pins:

[0086] Pin 1 is the HD pin, which is electrically connected to the drain of the upper MOSFET integrated inside the chip. At the same time, it is the input terminal of the self-powered circuit of the internal upper and lower MOSFETs and is connected to the HV+ terminal of the rectified and filtered DC input voltage.

[0087] Pin 2 is the BPH pin, which is connected to the bypass capacitors C2 and C4 of the gate drivers of the upper MOSFETs of U1 and U2, providing a self-powered voltage for the upper MOSFETs to operate.

[0088] Pin 3 is the SM pin, which is the self-configuring system monitoring input terminal. If this pin is connected to the system input voltage bus through a resistor, the system overvoltage and undervoltage faults will be detected automatically. If it is connected to the system ground through a thermistor, the system overtemperature fault will be detected automatically.

[0089] Pin 4 is the INH pin, which is the input terminal for controlling the gate drive of the upper MOSFET and is connected to the output pins of the system MCU PWM2 (U1) and PWM3 (U2).

[0090] Pin 5 is the INL pin, which is the input terminal for controlling the gate drive of the lower MOSFET and is connected to the output pins of the system MCU PWM1 (U1) and PWM4 (U2).

[0091] Pin 6 is the FAULT pin, which is the fault communication pin of the integrated chip and is connected to the system MCU I / O pin to provide system fault information.

[0092] Pin 7 is the IPH pin, which is grounded through small-signal resistors R2 and R7 to provide the drain current information \(i_{d1}\) and \(i_{d2}\) of the lower MOSFETs of U1 and U2 respectively; - 、i + ;

[0093] The 8-pin is the BPL pin, which is connected to the bypass capacitors C3 and C5 of the lower MOSFET gate drivers of U1 and U2, providing a self-powered voltage for the operation of the lower MOSFETs.

[0094] The 9-pin is the ID pin, which configures unique ID information for each chip through different connection methods.

[0095] The 10-pin is the SG pin, which is the connection point for the small-signal pin of the lower MOSFET controller and the ground reference of the system MCU.

[0096] The 11-pin is the XL pin, which is grounded through resistors R4 and R6, and is used to set the hardware current-limiting threshold of the lower MOSFETs of U1 and U2.

[0097] The 12-pin is the LS pin, which is electrically connected to the source of the lower MOSFET integrated inside the chip.

[0098] The 13-pin is the HB pin, which is connected to the source of the upper MOSFET and the drain of the lower MOSFET, and is connected to both ends of the contactor coil Coil1.

[0099] The 14-pin is the XH pin, which is connected to the half-bridge output through resistors R3 and R5, and is used to set the hardware current-limiting threshold of the upper MOSFETs of U1 and U2.

[0100] As Figure 4 shown, the flux-closed-loop control system constructs a voltage calculation module through Equation (1), converting the voltage u across the filter capacitor C1 into the voltage u across the contactor coil C1 : coil :

[0101]

[0102] where: u coil is the voltage across the contactor coil, A represents the polarity of the voltage across the coil, R8 and R9 are the resistance values of the voltage-dividing resistors, ΔT is the PWM period, and T on is the switch-on time.

[0103] When the contactor coil carries a positive current, the i output from the IPH pin of U2 + is positive; the i output from the IPH pin of U1 - is 0; when carrying a negative current, the i output from the IPH pin of U1 - is positive, and the i output from the IPH pin of U2 + is 0; compare i + and i - according to Equation (2) to determine the value of b, that is, to judge the direction of the coil current;

[0104]

[0105] After determining the value of b, construct a current calculation module according to Equation (3), and convert the currents i - , i + output from the IPH pins of U1 and U2 into the contactor coil current:

[0106] i coil = b * i b * g (3)

[0107] Where: i coil is the contactor coil current value, b represents the coil current direction, and i b is the output current of the selected IPH pin; g is the gain coefficient, which is related to the resistance values of R2 and R7.

[0108] Then, construct a magnetic flux calculation module according to Equation (4), and convert the coil voltage, current, and resistance into the magnetic flux of the magnetic circuit:

[0109] ψ coil = ∫(u coil - i coil R coil )dt (4)

[0110] Where: ψ coil is the magnetic flux of the magnetic circuit, u coil is the coil voltage, i coil is the coil current, and R coil is the coil resistance.

[0111] As Figure 5 shown, the four MOSFET switches S1, S2, S3, and S4 inside the two integrated chips U1 and U2 form a full-bridge control circuit. The MOSFET drive signals of the upper and lower bridge arms are strictly complementary, and a dead zone is inserted to prevent shoot-through; six circuit states are defined according to the voltage polarity applied across the coil and the coil current direction: ( Figure 5 The arrows and + signs in + indicate the positive directions of the coil current and voltage): When S1 and S4 are turned on simultaneously and S2 and S3 are turned off complementarily, a positive voltage is applied across the coil, causing the positive coil current to rise rapidly. Define this circuit state as +1 + state; when S1, S2, S3, and S4 are all turned off, and the positive coil current continues to flow through diodes D2 and D3, a negative coil voltage is applied across the coil, causing the positive current to drop rapidly. Define this circuit state as -1 + state; when only S4 is turned on and the positive coil current continues to flow through D2 and S4, the voltage across the coil is close to 0V, which can cause the positive coil current to drop slowly. Define the circuit state at this time as 0

[0112] When S1, S2, S3, and S4 are all turned off simultaneously and the negative coil current freewheels through D1 and D4, the positive coil voltage is applied across the coil ends, causing the absolute value of the negative current to decrease rapidly. This circuit state is defined as the +1 - state; when S2 and S3 are turned on simultaneously and S1 and S4 are complementarily turned off, the negative voltage is applied across the coil ends, causing the absolute value of the negative coil current to increase rapidly. This circuit state is defined as the -1 - state; when only S2 is turned on and the negative coil current freewheels through D4 and S2, the coil terminal voltage approaches 0V, causing the absolute value of the negative current to decrease slowly. This circuit state is defined as 0 - state.

[0113] In summary, the six circuit states are uniformly written in the form of A b , where A represents the polarity of the coil voltage and b represents the direction of the coil current. Since the direction and change trend of the contactor coil current are always consistent with those of the electromagnetic chain, Table 1 can be obtained. It can be seen from the table that by selecting the corresponding circuit state A b , the change direction and speed of the coil current or electromagnetic chain are controlled, laying a foundation for the flexible control of the excitation state of the permanent magnet contactor.

[0114] Table 1: Circuit State Selection Table

[0115]

[0116] In the table: 1 represents that the switch tube is turned on, 0 represents that it is turned off, ↑↑ represents a rapid increase in the absolute value, ↓↓ represents a rapid decrease in the absolute value, ↑ represents a slow increase in the absolute value, and ↓ represents a slow decrease in the absolute value

[0117] Construct a flux linkage hysteresis controller as shown in Figure 6 , where f s is the hysteresis frequency. By comparing ψ coil with ψ ref , Δψ is obtained, and the current direction is judged according to the input b value, and then it works according to the following logical relationship:

[0118] When i coil >0, select the upper half of the hysteresis control: when Δψ < 0, select the (80% +1 + , 20% 0 + ) circuit to make the flux linkage rise rapidly; when 0 < Δψ < ε, select the (80% 0 + , 20% 0 + ) circuit to make the flux linkage decrease slowly; when Δψ > ε, select the (80% -1 + , 20% 0 + ) circuit to make the flux linkage decrease rapidly.

[0119] When i coilWhen ≤ 0, select the lower half of the hysteresis control: when Δψ < -ε, select (80% + 1 - , 20% 0 - ) circuit to rapidly increase the magnetic flux linkage; when -ε < Δψ < 0, select (80% 0 - , 20% 0 - ) circuit to slowly increase the magnetic flux linkage; when Δψ > 0, select (80% - 1 - , 20% 0 - ) circuit to rapidly decrease the magnetic flux linkage.

[0120] Then, according to Table 1, the circuit state can be converted into drive signals S1 to S4; 20% 0 + or 0 - state is inserted in each hysteresis control period to balance the chip's dynamic self - power supply and current detection functions; the value of A is obtained according to the selected circuit state and returned to the voltage calculation module to calculate the coil voltage.

[0121] Under the action of the above magnetic flux hysteresis, optimize the control of the operation process of the monostable permanent - magnet contactor: during the starting process, set the magnetic flux reference value to a constant value. As the air gap between the moving and static iron cores decreases, automatically adjust the magnitude and direction of the exciting current so that the total magnetic flux composed of the electromagnetic magnetic flux and the permanent - magnet magnetic flux is dynamically stabilized at the reference value, and the contactor starts with a constant magnetic flux; during the stable holding process, turn off the four internal switch tubes, and the contactor is stably held in the attracted state by the permanent - magnet force; during the breaking process, set the magnetic flux reference value to 0. As the air gap between the moving and static iron cores increases, automatically adjust the magnitude of the demagnetizing current so that the total magnetic flux composed of the electromagnetic magnetic flux and the permanent - magnet magnetic flux is always 0, and the contactor completes the breaking at the fastest speed, thus realizing the magnetic - flux closed - loop control during the starting and breaking processes of the monostable permanent - magnet contactor.

[0122] During the constant - magnetic - flux starting and breaking processes of the monostable permanent - magnet contactor, when the coil current exceeds the current - limiting thresholds set by resistors R3, R4 and R5, R6, the integrated chip can perform hardware self - locking current - limiting on the switch tubes, thereby protecting the drive circuit from damage and serving as the final hardware over - current protection. However, during the magnetic - flux closed - loop control process of the permanent - magnet contactor, it is necessary to perform per - cycle current - limiting on the coil current. Therefore, on the basis of the constant - magnetic - flux starting and breaking of the permanent - magnet contactor, further perform per - cycle current - limiting control on the coil current. The specific control method is as follows: output the current - limiting threshold i max through the programmable DAC. The coil current i coil and the current - limiting threshold i max are connected to the internal PWM module of the MCU through the internal comparator of the MCU. When the coil current i coil is greater than the set current - limiting threshold i max , a complementary turn - off signal is output to the PWM module through the comparator, causing the switch tube to be turned off for one PWM cycle until the coil current icoil Less than the current limiting threshold i max When the PWM cycle is reopened, the switch tube performs flux closed-loop control according to the above hysteresis control method, and performs software-programmable cycle-by-cycle current limiting on the basis of flux closed-loop control to control the maximum value of the coil current, so as to achieve reliable operation of the permanent magnet contactor during the flux closed-loop control process.

[0123] The integrated flux closed-loop control system of the monostable permanent magnet contactor provided by the present invention cleverly applies the switching power supply chip to the control of the monostable permanent magnet contactor, and the device has high integration, reliable circuit, small size and low cost; the upper and lower tube drivers both work in a self-biased power supply mode, which overcomes the defect that the traditional permanent magnet contactor driving solution requires an auxiliary working power supply, and further reduces the size and cost; the chip provides accurate and real-time current output information, and no external current detection circuit is required, which further simplifies the hardware control solution; a hardware-adjustable current limiting threshold is provided externally, and once the current limiting value is exceeded, a self-locking PWM output is performed, and safety can be guaranteed even in the case of a short-circuit fault; in conjunction with the on-chip operational amplifier and programmable DAC peripheral of the single-chip microcomputer, flexible software cycle-by-cycle current limiting can be achieved, and under the single closed-loop control of the flux, it has a flexible forward and reverse current maximum value limiting capability, improves the reliability of the closed-loop control, and reduces the permanent demagnetization risk of the permanent magnet.

[0124] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. An integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor, characterized in that, It includes an integrated drive circuit and a flux closed-loop control system. The integrated drive circuit includes a rectifier bridge B1, a filter capacitor C1, integrated chips U1 and U2, a driving permanent magnet contactor coil Coil1, capacitors C2, C3, C4, C5, and resistors R1, R2, R3, R4, R5, R6, R7, R8, R9. The rectifier bridge B1 and the filter capacitor C1 rectify the AC input voltage into a stable DC voltage. The chips U1 and U2 form a full-bridge circuit. C2, C3 and C4, C5 are the self-bias capacitors of the internal integrated switching tubes of U1 and U2 respectively, providing dynamic self-power supply voltages for the internal upper and lower tubes. R3, R4 and R5, R6 are the current-limiting resistors of the upper and lower tubes of U1 and U2 respectively, providing a hardware-adjustable self-locking current-limiting threshold for the chips. R2 and R7 are current detection resistors, used to detect the currents flowing through the drain electrodes of the lower tubes of U1 and U2 respectively. R8 and R9 form a resistor voltage-dividing circuit, which is used to reflect the voltage across the coil Coil1 through corresponding conversion. R1 is the system bus input voltage detection resistor. The 3-pin of the U1 chip is connected to the input voltage bus through R1 to monitor the over-voltage and under-voltage of the system in real time. In addition, fault information including over-voltage, under-voltage, over-current, and over-temperature is sent to the system MCU through the 6-pin of the chip. The unique ID information is set for each chip through different connection methods of the 9-pin, which is used to quickly locate the faulty chip and the type of fault. The flux closed-loop control system adopts constant flux closed-loop control during the starting process of the permanent magnet contactor; and adopts constant zero flux control during the breaking process to make the electromagnetic flux completely cancel the permanent magnet flux at all times. During the constant magnetic flux starting and breaking processes of the monostable permanent magnet contactor, when the coil current exceeds the current limiting thresholds set by resistors R3, R4 and R5, R6, the integrated chip can perform hardware self-locking current limiting on the switching tubes, thus protecting the drive circuit from damage and serving as the ultimate hardware overcurrent protection; based on the constant magnetic flux starting and breaking of the permanent magnet contactor, the coil current is controlled with per-cycle current limiting, and the control method is as follows: the current limiting threshold i max is output through the programmable DAC, and the coil current i coil and the current limiting threshold i max are connected to the internal PWM module of the MCU through the internal comparator of the MCU. When the coil current i coil is greater than the set current limiting threshold i max , a complementary turn-off signal is output to the PWM module through the comparator, causing the switching tube to turn off for one PWM cycle until the coil current i coil is less than the current limiting threshold i max , at which time the PWM cycle will be reopened, and the switching tube performs magnetic flux closed-loop control in a hysteresis control manner. Based on the magnetic flux closed-loop control, per-cycle current limiting that can be software-programmed is carried out to control the maximum value of the coil current.

2. The integrated magnetic flux closed-loop control system of a monostable permanent magnet contactor according to claim 1, wherein The magnetic flux closed-loop control system detects the coil current i of the permanent magnet contactor through the 7th pins of U1 and U2 coil , and detects the coil voltage u through the voltage-dividing resistors R8 and R9 coil , the coil current i coil and the coil voltage u coil calculate the magnetic flux of the magnetic circuit according to the following formula: ψ coil = ∫(u coil - i coil R coil ) dt Where: ψ coil is the magnetic flux linkage of the magnetic circuit, u coil is the coil voltage, i coil is the coil current, R coil is the coil resistance; Four MOSFET switches S1, S2, S3, and S4 inside two chips U1 and U2 form a full-bridge control circuit. The MOSFET drive signals of the upper and lower bridge arms are strictly complementary and a dead zone is inserted to prevent shoot-through. Four circuit states are defined according to the voltage polarity across the coil and the coil current direction: When S1 and S4 are conducting simultaneously and S2 and S3 are complementarily turned off, the rectified and filtered positive voltage is applied across the coil, causing the coil to be quickly magnetized in the positive direction. This circuit state is defined as the +1 state at this time; when S1 and S4 are turned off simultaneously and S2 and S3 are complementarily conducting, the negative capacitor voltage is applied across the coil, forcing the coil to quickly demagnetize or be magnetized in the negative direction. This circuit state is defined as the -1 state at this time; when only S4 is conducting and the coil current is flowing forward through the freewheeling diode D2 of S2 and S4, the voltage across the coil is close to 0V. This circuit state is defined as the 0 + state; when only S2 is conducting and the coil current is flowing backward through the freewheeling diode D4 of S4 and S2, the voltage across the coil is also close to 0V. This circuit state is defined as the 0 - state; the 0 + state and the 0 - state in these two circuit states, the coil current decreases slowly and the magnetic circuit demagnetizes slowly.

3. The integrated magnetic flux closed-loop control system of a monostable permanent magnet contactor according to claim 2, characterized in that, The flux closed-loop control system adopts a hysteresis control method for regulation and realizes flux closed-loop control according to the following method: By comparing and calculating the flux value ψ coil with the reference flux value ψ ref to obtain the flux error Δψ, that is: Δψ = ψ coil - ψ ref , according to the flux error Δψ and the hysteresis width ε, automatically select the appropriate circuit state and convert it into the driving state of the corresponding switching tube according to the switching table. The specific conversion is as follows: When Δψ < 0, turn on the switch tubes S1 and S4, turn off the switch tubes S2 and S3, and select the +1 state circuit to rapidly and positively excite the coil, so that the magnetic flux linkage ψ of the magnetic circuit coil rapidly reaches the set reference magnetic flux ψ ref ; when 0 ≤ Δψ ≤ ε, automatically select 0 according to the coil current direction + and 0 - for the two circuit states. When the coil has a positive current flowing through it, turn on the switch tube S4, turn off the switch tubes S1, S2, and S3, and make the coil current flow positively for continuous current. When the coil has a negative current flowing through it, turn on the switch tube S2, turn off the switch tubes S1, S3, and S4, and make the coil current flow negatively for continuous current. Through 0 + and 0 - for the two circuit states, make the positive or negative coil current slowly decrease, so that the coil magnetic circuit slowly demagnetizes; when Δψ > ε, turn on the switch tubes S2 and S3, turn off the switch tubes S1 and S4, and select the -1 state circuit to rapidly demagnetize the coil or negatively excite it.

4. The integrated magnetic flux closed-loop control system of a monostable permanent magnet contactor according to claim 3, characterized in that, Under the action of the flux hysteresis loop, the optimization control of the action process of the monostable permanent magnet contactor is carried out: during the starting process, the flux reference value is set to a constant value. As the air gap between the moving and static iron cores decreases, the magnitude and direction of the exciting current are automatically adjusted to make the total flux composed of the electromagnetic flux and the permanent magnet flux dynamically stable at the reference value, and the contactor starts with constant flux. During the stable holding process, the four internal switching tubes are turned off, and the contactor is stably held in the attracted state by the permanent magnet force. During the breaking process, the flux reference value is set to 0. As the air gap between the moving and static iron cores increases, the magnitude of the demagnetizing current is automatically adjusted to make the total flux composed of the electromagnetic flux and the permanent magnet flux always 0, and the contactor completes the breaking at the fastest speed, thus realizing the flux closed-loop control during the starting and breaking processes of the monostable permanent magnet contactor.

5. The integrated magnetic flux closed-loop control system of a monostable permanent magnet contactor according to claim 1, characterized in that, The integrated chips U1 and U2 are both BRD1267C integrated half-bridge chips, and they include the following pins: The 1-pin is the HD pin, which is electrically connected to the drain of the upper MOSFET integrated inside the chip. At the same time, it is the input end of the self-power supply circuit of the internal upper and lower MOSFETs, and is connected to the HV+ end of the rectified and filtered DC input voltage. The 2-pin is the BPH pin, which is connected to the bypass capacitors C2 and C4 of the gate drivers of the upper MOSFETs of U1 and U2, providing a self-power supply voltage for the upper tube to work. Pin 3 is the SM pin, which is the self - configured system monitoring input terminal. If this pin is connected to the system input voltage bus through a resistor, it will self - detect system over - voltage and under - voltage faults. If it is connected to the system ground through a thermistor, it will self - detect system over - temperature faults. Pin 4 is the INH pin, which is the upper - MOSFET gate - drive control input terminal and is connected to the system MCU PWM2 (U1), PWM3 (U2) output pins. Pin 5 is the INL pin, which is the lower - MOSFET gate - drive control input terminal and is connected to the system MCU PWM1 (U1), PWM4 (U2) output pins. Pin 6 is the FAULT pin, which is the integrated - chip fault communication pin and is connected to the system MCU I / O pin to provide system fault information. Pin 7, namely the IPH pin, is grounded through small-signal resistors R2 and R7, providing the drain current information i of the lower MOSFETs of U1 and U2 respectively - , i + ; Pin 8 is the BPL pin, which is connected to the bypass capacitors C3, C5 of the lower - MOSFET gate drivers of U1 and U2 to provide self - supply voltage for the lower - tube operation. Pin 9 is the ID pin, which configures unique ID information for each chip through different connection methods. Pin 10 is the SG pin, which is the connection point between the small - signal pin of the lower - tube controller and the system MCU ground reference. Pin 11 is the XL pin, which is grounded through resistors R4, R6 and is used to set the hardware current - limiting threshold of the lower - MOSFETs of U1 and U2. Pin 12 is the LS pin, which is electrically connected to the source of the lower - MOSFET integrated inside the chip. Pin 13 is the HB pin, which is connected to the source of the upper - MOSFET and the drain of the lower - MOSFET and is connected to both ends of the contactor coil Coil1. Pin 14 is the XH pin, which is connected to the half - bridge output through resistors R3, R5 and is used to set the hardware current - limiting threshold of the upper - MOSFETs of U1 and U2.

6. The integrated magnetic flux closed-loop control system of a monostable permanent magnet contactor according to claim 5, characterized in that The magnetic flux closed-loop control system constructs a voltage calculation module through Equation (1) to convert the voltage u across the filter capacitor C1 into the voltage u across the contactor coil C1 : coil ​ Where: u coil is the voltage across the contactor coil, A represents the polarity of the voltage across the coil, R8 and R9 are the resistance values of the voltage dividing resistors, ΔT is the PWM period, T on is the switch conduction time; When a positive current flows through the contactor coil, the i output from the IPH pin of U2 + is positive; the i output from the IPH pin of U1 - is 0; when a reverse current flows, the i output from the IPH pin of U1 - is positive, and the i output from the IPH pin of U2 + is 0; compare i + and i - according to Equation (2) to determine the value of b, that is, to judge the direction of the coil current; After determining the b value, construct a current calculation module according to Equation (3), and convert the currents i - and i + output from the IPH pins of U1 and U2 into the contactor coil current: i coil = b * i b * g(3) Where: i coil is the contactor coil current value, b represents the coil current direction, i b is the output current of the selected IPH pin; g is the gain coefficient, which is related to the resistance values of R2 and R7; Then, construct the flux - linkage calculation module according to Equation (4) to convert the coil voltage, current, and resistance into the magnetic - circuit flux - linkage. ψ coil = ∫(u coil - i coil R coil )dt(4) Where: ψ coil is the magnetic flux linkage of the magnetic circuit, u coil is the coil voltage, i coil is the coil current, R coil is the coil resistance; Four MOSFET switches S1, S2, S3, and S4 inside two integrated chips U1 and U2 form a full-bridge control circuit. The MOSFET drive signals of the upper and lower bridge arms are strictly complementary and a dead zone is inserted to prevent shoot-through. Six circuit states are defined according to the voltage polarity across the coil and the direction of the coil current: When S1 and S4 are conducting simultaneously and S2 and S3 are complementarily off, a positive voltage is applied across the coil, causing the positive coil current to rise rapidly. This circuit state is defined as the +1 + state; When S1, S2, S3, and S4 are all off and the positive coil current freewheels through diodes D2 and D3, a negative coil voltage is applied across the coil, causing the positive current to drop rapidly. This circuit state is defined as the -1 + state; When only S4 is conducting and the positive coil current freewheels through D2 and S4, the voltage across the coil is close to 0V, which can cause the positive coil current to drop slowly. This circuit state is defined as 0 + state; When S1, S2, S3, and S4 are all turned off simultaneously, and the negative coil current continues to flow through D1 and D4, the positive coil voltage is applied across the coil ends, causing the absolute value of the negative current to rapidly decrease. This circuit state is defined as the +1 - state; when S2 and S3 are turned on simultaneously, and S1 and S4 are complementarily turned off, the negative voltage is applied across the coil ends, causing the absolute value of the negative coil current to rapidly increase. This circuit state is defined as the -1 - state; when only S2 is turned on, and the negative coil current continues to flow through D4 and S2, the coil terminal voltage approaches 0V, causing the absolute value of the negative current to slowly decrease. This circuit state is defined as 0 - state; The six circuit states are uniformly written in the form of A b , where A represents the coil voltage polarity and b represents the coil current direction. By selecting the corresponding circuit state A b , the change direction and change speed of the coil current or the magnetic flux linkage are controlled.

7. An integrated magnetic flux closed-loop control system for a monostable permanent magnet contactor according to claim 6, characterized in that, Construct a flux linkage hysteresis controller. By comparing ψ coil with ψ ref to obtain Δψ, and determine the current direction according to the input b value, and then work according to the following logical relationship: When i coil > 0, select the upper half of the hysteresis control: when Δψ < 0, select (80% + 1 + , 20% 0 + ) circuit to rapidly increase the flux linkage; when 0 < Δψ < ε, select (80% 0 + , 20% 0 + ) circuit to slowly decrease the flux linkage; when Δψ > ε, select (80% - 1 + , 20% 0 + ) circuit to rapidly decrease the flux linkage; When i coil ≤ 0, select the lower half of the hysteresis control: when Δψ < -ε, select the (80% + 1 - , 20% 0 - ) circuit to make the magnetic flux rise rapidly; when -ε < Δψ < 0, select the (80% 0 - , 20% 0 - ) circuit to make the magnetic flux rise slowly; when Δψ > 0, select the (80% - 1 - , 20% 0 - ) circuit to make the magnetic flux drop rapidly; Then convert the circuit state into drive signals S1 to S4; insert 20% 0 + or 0 - state in each hysteresis control cycle for taking into account the chip's dynamic self-power supply and current detection functions; obtain value A according to the selected circuit state and return A to the voltage calculation module to calculate the coil voltage.

8. An integrated magnetic flux closed-loop control system of a monostable permanent magnet contactor according to claim 7, characterized in that, Under the action of the flux - linkage hysteresis, optimize the control of the operation process of the single - stable permanent - magnet contactor: During the starting process, set the flux - linkage reference value as a constant value. As the air gap between the moving and static iron cores decreases, automatically adjust the magnitude and direction of the exciting current so that the total flux - linkage composed of the electromagnetic flux - linkage and the permanent - magnet flux - linkage is dynamically stable at the reference value, and the contactor starts with a constant flux - linkage. During the stable - holding process, turn off the four internal switching tubes, and the contactor is stably held in the attracted state by the permanent - magnet force. During the breaking process, set the flux - linkage reference value to 0. As the air gap between the moving and static iron cores increases, automatically adjust the magnitude of the demagnetizing current so that the total flux - linkage composed of the electromagnetic flux - linkage and the permanent - magnet flux - linkage is always 0, and the contactor completes the breaking at the fastest speed, thus realizing the flux - linkage closed - loop control of the starting and breaking processes of the single - stable permanent - magnet contactor.

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