Permanent magnet switch driving control method and system based on equivalent constant current technology

Abstract

The application belongs to the technical field of power electronics and switching appliance control, and particularly relates to a permanent magnet switch driving control method and system based on equivalent constant current technology, which comprises a wide voltage input power supply module, a main control module adopting STM8S003F, a current detection module, a driving control module, a power driving module and a closing and opening interlocking module; the method replaces capacitor direct discharge with PWM closed loop control, the driving control module dynamically adjusts the PWM duty cycle according to the real-time collected coil current, and equivalent constant current output is realized; the driving control module and the power driving module are separately arranged, and the strong and weak electric isolation is sufficient; the closing and opening interlocking module is arranged between the power driving module and the coil, and the power stage hardware interlocking is used to ensure that the closing and opening power paths are not simultaneously conducted. The permanent magnet switch driving control method and system based on equivalent constant current technology provided by the application can reduce the peak current, reduce power consumption, support wide range input, and prolong the service life of the permanent magnet.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of power electronics technology and switching appliance control, specifically a permanent magnet switch drive control method and system based on equivalent constant current technology. Background Technology Permanent magnet switches, as a new type of switching device, combine the characteristics of permanent magnets with electromagnetic operating mechanisms. They are used in pole-mounted circuit breakers, 10kV reactive power compensation switching switches, reclosers, and other related products in power distribution networks, and have been widely applied in the medium-voltage power distribution field. Permanent magnet switches utilize the magnetic force generated by permanent magnets to hold vacuum circuit breakers in the closed or open position, eliminating the need for traditional mechanical tripping or locking devices. They offer advantages such as simple structure, fewer parts, and high reliability. The drive control of permanent magnet switches mainly relies on the energization control of internal coils, achieving rapid opening and closing operations by changing the polarity of the magnetic field inside the permanent magnet drive mechanism.

[0002] Traditional permanent magnet switch drive control methods primarily employ capacitor energy storage and direct discharge. By pre-charging the energy storage capacitor to a set voltage, when a switching operation is required, the capacitor is connected to the internal coil of the switch mechanism, instantaneously releasing a large current to drive the permanent magnet mechanism. In practical applications, conventional control methods typically only control the conduction time of the permanent magnet, lacking precise adjustment mechanisms for the drive current itself, and mainly relying on the instantaneous discharge of the large-capacity capacitor to obtain sufficient drive energy.

[0003] However, existing technologies have the following obvious shortcomings: 1. Conventional control methods only control the conduction time of the permanent magnet and use direct capacitor discharge. Traditional direct capacitor discharge can lead to excessively high instantaneous current peaks in the coil, resulting in severe current surges. Excessive current surges accelerate the aging of the permanent magnet and coil, shortening the equipment's lifespan. Current surges can also cause excessively fast contact collision speeds, leading to mechanical deformation and bouncing, further affecting the lifespan of the permanent magnet operating mechanism and the reliability of the circuit breaker.

[0004] 2. To meet the instantaneous high current demand, traditional solutions require large-capacity power supplies and energy storage capacitors. Some permanent magnet switches use 220V voltage and 22000μF capacitors for energy storage and discharge, which not only occupies a large volume but also has high system energy consumption. In addition, conventional energy storage capacitor charging uses a constant voltage method without protection, resulting in current spikes at the beginning of charging. Furthermore, as the energy storage capacitor voltage rises, the charging current decreases rapidly, increasing the charging time and further reducing energy utilization efficiency.

[0005] 3. Existing drive power supplies have a narrow voltage range and can usually only operate in a single voltage mode of AC 220V or DC 110V, which cannot be compatible with a wide range of voltage input scenarios. When the grid voltage fluctuates greatly, it may cause the permanent magnet switch to operate unreliably, or even fail to close properly.

[0006] 4. In existing permanent magnet switch drive schemes, the interlocking of opening and closing control mostly relies on software logic. When system reset, chip malfunction, or program crash occurs, software interlocking alone cannot guarantee that the opening and closing signals do not overlap. Once the opening and closing signals are output simultaneously, it will cause the upper and lower bridge arms of the H-bridge circuit to be directly connected, resulting in a serious short circuit fault.

[0007] Existing patents, such as CN115497774A, disclose a control method for a single-coil permanent magnet switch driver. This method uses an independent capacitor as the energy storage capacitor for opening and closing, decoupling the opening and closing controls and improving the reliability of the opening action under fault conditions. However, this method still does not solve the problems of large current surges and narrow power supply adaptability. CN215496458U proposes a permanent magnet switch driver module with self-testing and dual-circuit automatic switching. This improves system reliability through a main / backup dual-circuit design, but it also does not optimize the current control method. Summary of the Invention

[0008] To address the technical problems existing in the background art, the present invention provides a permanent magnet switch drive control method and system based on equivalent constant current technology, which reduces peak current, reduces power consumption, supports wide range input, and extends the life of permanent magnets.

[0009] The technical solution adopted by this invention is: A permanent magnet switch drive control method based on equivalent constant current technology includes: S1: The system is powered on, and the main control module (2) performs initial parameter configuration to complete the initialization of the drive time and constant current target value; S2: Enable the drive control module (4). The drive control module (4) automatically adjusts the duty cycle through PWM closed-loop control based on the coil current collected in real time by the current detection module (3) so that the drive current is maintained within the set constant current threshold range. S3: While enabling the drive control module (4), the main control module (2) starts the internal timer, records the drive duration, and synchronously detects the working status of the drive coil. It then uses the hardware interlock circuit to determine whether the opening and closing signals overlap. S4: When the timer inside the main control module (2) reaches the preset drive time threshold, the drive control module (4) is turned off and the power output is stopped.

[0010] Furthermore, the PWM closed-loop control adopts a segmented PWM strategy: During the startup phase, a first duty cycle is used to quickly build up the current, and during the steady-state phase, a second duty cycle is used to maintain constant current output, wherein the first duty cycle is greater than the second duty cycle.

[0011] Furthermore, the preset drive time threshold is 100ms, and the constant current target value is preset according to the parameters of the permanent magnet switch coil block (6).

[0012] Furthermore, in step S3: If no action signal is detected in the corresponding drive coil after enabling, the fault type is determined based on whether the hardware interlock protection is effective: If the interlock protection is active, it is determined that the interlock has started; if the interlock protection is not active, it is determined that there is a hardware failure, and the driving result is indicated by the indicator light.

[0013] Furthermore, it also includes a status feedback step: The system determines whether the opening and closing action has been completed by checking the returned remote signaling points for the opening and closing status. If the action has not been completed, an alarm signal is issued.

[0014] A permanent magnet switch drive control system based on equivalent constant current technology includes: Power supply module (1) is used to convert a wide range of input voltages into a stable DC drive power supply; The main control module (2) is used to monitor the working status of each module, perform communication transmission and reception, execute control commands, and set constant current thresholds; The current detection module (3) is used to collect the current of the drive coil in real time and feed it back to the drive control module (4). The drive control module (4) is used to generate PWM signals to control the on / off state of the power devices and achieve equivalent constant current output through closed-loop regulation; The opening and closing interlock module (5) is used to ensure that the opening signal and the closing signal are not output simultaneously through a hardware interlock circuit.

[0015] Furthermore, the power supply module (1) adopts a wide voltage input design, including: AC / DC conversion circuits and DC / DC conversion circuits automatically identify the input voltage type and amplitude, supporting a wide input range of 100-260V AC and 80-300V DC.

[0016] Furthermore, the drive control module (4) adopts PWM constant current control mode, and changes the PWM duty cycle by monitoring the magnitude of the drive current in real time to achieve equivalent constant power output; The PWM control frequency is 20kHz-100kHz.

[0017] Furthermore, the split-combination interlock module (5) includes: a hardware interlock circuit and a software interlock logic; The hardware interlock circuit is implemented through logic gate circuits. When the opening signal and the closing signal are both valid, the hardware interlock circuit blocks the two drive outputs.

[0018] Furthermore, the main control module (2) has a built-in drive start recording unit and drive time counting unit, which automatically shuts off the drive output when the drive duration reaches a preset threshold. The main control module (2) is also provided with a communication interface for communicating with the host computer, which is used to upload working status and receive control commands.

[0019] The beneficial effects of the permanent magnet switch drive control method and system based on equivalent constant current technology of the present invention are as follows: 1. By replacing direct capacitor discharge with PWM closed-loop constant current control, smooth current control is achieved, peak current is reduced, and the electrical stress impact on permanent magnets and coils is reduced, thereby extending the equipment life.

[0020] 2. Equivalent constant current control enables the drive energy to be output on demand, avoiding ineffective current spike consumption, reducing drive power consumption, and reducing the requirements for power supply capacity.

[0021] 3. The power supply module supports a wide range of inputs and automatically identifies voltage type and amplitude, greatly improving its adaptability to power grid fluctuations.

[0022] 4. The dual interlocking mechanism of hardware and software ensures that the opening and closing signals do not overlap, preventing the opening and closing coils from operating simultaneously; the time-limited control of the drive time prevents the coil from being damaged by prolonged energization.

[0023] 5. As the peak current and power capacity requirements are reduced, the size of the power module and energy storage element can be reduced accordingly, which is conducive to the deep integration of secondary control and primary switching. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall architecture of an example of the present invention; Figure 2 This is a schematic diagram of PWM closed-loop regulation in an example of the present invention; Figure 3 This is a schematic diagram of the constant current drive circuit in an example of the present invention; Figure 4 This is a schematic diagram of the interlock protection circuit for separation and reconnection in an embodiment of the present invention; Figure 5 This is a schematic diagram of the main control module circuit in an example of the present invention.

[0025] In the picture: 1. Power supply module; 2. Main control module; 3. Current detection module; 4. Drive control module; 5. Interlocking module for opening and closing; 6. Permanent magnet switch coil; 7. Tripping coil; 8. Closing coil; 9. Power drive module. Detailed Implementation

[0026] To more clearly and explicitly illustrate the specific objectives and implementation methods of this invention, a complete description of the technical solution of this invention will be provided below. The described embodiments are only a part of the embodiments of this invention, not all of them. Without creative effort, all other embodiments based on the embodiments described in this invention are within the protection scope of this invention.

[0027] This invention discloses a permanent magnet switch drive control system based on equivalent constant current technology, such as... Figure 1 As shown, it includes: Power supply module 1, main control module 2, current detection module 3, drive control module 4, opening and closing interlock module 5, permanent magnet switch coil 6, power drive module 9.

[0028] The output of power supply module 1 is connected to the power input of main control module 2, drive control module 4, and power drive module 9 respectively, providing working power to each module; the control signal output of main control module 2 is connected to the control input of drive control module 4 and the signal input of switch-close interlock module 5 respectively; current detection module 3 is connected in series in the drive coil circuit, and its signal output is connected to the current feedback input of drive control module 4; the PWM control signal output of drive control module 4 is connected to the control input of power drive module 9; the power output of power drive module 9 is connected to the permanent magnet switch coil 6 of permanent magnet switch via switch-close interlock module 5; permanent magnet switch coil 6 is composed of opening coil 7 and closing coil 8, and current detection module 3, drive control module 4, and power drive module 9 are respectively set in the circuit of opening coil 7 and the circuit of closing coil 8; switch-close interlock module 5 is set between drive control module 4 and power drive module 9 in the circuit of opening coil 7 and the circuit of closing coil 8 to ensure that the path from power output stage to coil is controlled by interlock logic at the hardware level.

[0029] The drive control module 4 generates a PWM control signal, which serves as the input control signal for the power drive module 9. This signal controls the switching of the power devices within the power drive module 9. The power drive module 9 performs actual power conversion and current amplification, chopping the DC bus voltage provided by the power supply module 1 into a high-frequency pulse voltage and applying it across the permanent magnet switch coil 6. The current detection module 3 is connected in series in the output circuit of the power drive module 9, detecting the actual current flowing through the coil and feeding it back to the drive control module 4, thus forming a current closed-loop control circuit.

[0030] Based on the overall architecture of a permanent magnet switch drive control system based on equivalent constant current technology in the above embodiments, the specific implementation methods of each component are further described below: In this embodiment, the power supply module 1 adopts a wide voltage input design, such as... Figure 3 As shown, it supports a wide input range of 100-260V AC and 80-300V DC; the power supply module 1 internally consists of an AC / DC conversion circuit, a DC / DC conversion circuit, and an input voltage type automatic identification circuit, wherein: The AC / DC conversion circuit adopts a wide voltage input switching power supply topology. The front stage is equipped with an EMI filter circuit and a surge suppression circuit to suppress electromagnetic interference in the power grid and the inrush current at the moment of power-on. The rectification section adopts a bridge rectifier. After rectification, the power factor is improved by a PFC power factor correction circuit, and then a high-efficiency isolated conversion is achieved through an LLC resonant converter to output a stable DC bus voltage.

[0031] The DC / DC conversion circuit and the AC / DC conversion circuit share the DC bus at the output terminal. When the input is DC, the automatic input voltage type identification circuit detects that the input is DC and automatically bypasses the front-stage rectification section of the AC / DC conversion circuit, so that the DC power directly enters the subsequent conversion circuit. When the input is AC, the automatic input voltage type identification circuit detects that the input is AC and automatically switches to the AC / DC conversion path.

[0032] The automatic input voltage type identification circuit is a voltage zero-crossing detection comparator; when a zero-crossing point is detected in the input voltage and the zero-crossing point frequency matches the grid frequency, the input is determined to be AC; when the zero-crossing point disappears and the polarity of the input voltage remains constant, the input is determined to be DC; the identification result is sent to the main control module 2 after being isolated by an optocoupler.

[0033] In this embodiment, the power supply module 1 provides a stable DC power supply to the main control module 2, the drive control module 4, and the power drive module 9.

[0034] In this embodiment, as Figure 5As shown, the main control module 2 uses an STM8S003F microcontroller as its core processor, with a maximum operating frequency of 16MHz. It integrates 8KB Flash program memory, 1KB RAM data memory, and 640 bytes of EEPROM data memory. It has a general-purpose input / output interface, an ADC converter, multiple timers, and a UART communication interface to meet the real-time requirements of permanent magnet switch drive control. In this embodiment, a 3.3V power supply is used.

[0035] The hardware circuit of main control module 2 includes: an STM8S003F microcontroller chip, a power supply circuit, a reset circuit, a signal input circuit, and a signal output circuit, wherein: The power supply circuit uses a 3.3V low dropout linear regulator to filter the 3.3V voltage provided by power supply module 1 and send it to the power supply pin of the microcontroller. A 0.1μF and a 10μF capacitor are connected in parallel at the power supply pin for decoupling.

[0036] The reset circuit adopts an RC reset circuit, which generates a 200ms low-level reset pulse when powered on to ensure reliable reset of the microcontroller; the VCAP pin of the microcontroller is connected to an external 1μF capacitor for filtering the internal 1.8V core voltage.

[0037] The communication interface of the main control module 2 adopts UART asynchronous serial communication, which is converted into RS-485 bus signals by an isolated RS-485 transceiver. The communication protocol adopts Modbus-RTU protocol, which enables network monitoring of multiple permanent magnet switch drive controllers, facilitating the integrated management of the power distribution network automation system.

[0038] The main control module 2 internally uses the 16-bit general-purpose timer TIM2 of STM8S003F to implement the drive time counting unit. When the drive enable signal is valid, the timer starts counting, and the timing accuracy can reach 1μs, ensuring precise control of the drive time. When the drive duration reaches the preset drive time threshold, the timer overflow interrupt service routine automatically shuts down the drive output. Even if the main program encounters an exception, the timer interrupt can still reliably perform the shutdown operation to ensure that the drive time does not exceed the limit.

[0039] The main control module 2 utilizes its internal EEPROM to implement a driver startup recording unit, recording the startup time and operation type of each driver operation to form an operation log, facilitating fault tracing and maintenance management. Each operation record occupies 8 bytes of storage space, and the EEPROM's 100,000 erase / write cycles can meet the recording needs throughout the device's entire lifecycle.

[0040] The main control module 2 determines whether the opening and closing action is completed by checking the returned remote signaling points for the opening and closing status. The remote signaling points are acquired using a non-contact Hall effect sensor to detect the position of the moving iron core of the permanent magnet switch. When the moving iron core moves to the closed position, the PD4 pin is low, and the closing remote signaling point is closed. When the moving iron core moves to the open position, the PD3 pin is low, and the opening remote signaling point is closed. If the corresponding remote signaling point does not return an action completion signal within the set time after the drive enable ends, the main control module 2 determines that the action has failed, issues an alarm signal, and indicates this via an indicator light; in this embodiment, this is set to 120ms.

[0041] In this embodiment, the current detection module 3 is connected in series in the output circuit of the power drive module 9, that is, in the circuit between the interlock module 5 and the permanent magnet switch coil 6, and is used to collect the actual current signal flowing through the permanent magnet switch drive coil in real time. The current detection module 3 has the characteristics of fast response speed, good linearity and high isolation voltage. The rated detection current range is ±30A and the bandwidth is 80kHz, which meets the requirements of real-time current detection under PWM control frequency.

[0042] The current sampling signal is sent to the comparator input of the drive control module 4 for PWM closed-loop control.

[0043] To improve the accuracy of current detection, the current detection module 3 also includes a second-order low-pass active filter with a cutoff frequency set to 200kHz. This filter removes high-frequency noise components introduced by the PWM switching frequency while retaining the effective DC sampling signal. The filtered current signal is buffered by a voltage follower and then output to the drive control module 4.

[0044] The current detection module 3 also includes an overcurrent protection comparator circuit. When the detected current exceeds the set overcurrent threshold (12A in this embodiment), the overcurrent protection comparator immediately flips, directly blocking the drive input signal of the power drive module 9 in hardware. The response time is less than 5μs, achieving hardware-level fast overcurrent protection. This overcurrent protection threshold is fixed in the circuit design using a resistor divider network and does not depend on software settings, ensuring that the overcurrent protection function can operate independently and reliably under any software abnormality.

[0045] In this embodiment, the drive control module 4 is the core calculation and signal generation unit of the equivalent constant current control. Its function is to perform closed-loop regulation calculation based on the drive enable signal issued by the main control module 2 and the actual coil current signal fed back by the current detection module 3, and generate a PWM control signal with a corresponding duty cycle. This PWM control signal serves as the input control signal of the power drive module 9, controlling the on / off state of the power devices in the power drive module 9 to achieve closed-loop constant current regulation of the coil current. The drive control module 4 is a signal-level control unit, and its output is a PWM pulse signal. It does not directly undertake the power output function. The power output is independently completed by the subsequent power drive module 9. By separating the control stage from the power stage, strong and weak current isolation and physical isolation between the heat source of the power device and the heat source of the control circuit are achieved, improving the reliability and anti-interference capability of the system.

[0046] The hardware circuit of drive control module 4 includes: a PWM signal generation circuit, a current loop PI adjustment circuit, a PWM duty cycle limiting circuit, a segmented gain switching circuit, a soft-start circuit, and a fault synthesis circuit, among which: The PWM signal generation circuit is implemented based on a pulse width modulation chip. The chip integrates a voltage reference source, oscillator, error amplifier, and PWM comparator, and can independently generate PWM signals without relying on the software generation of the main control module 2, thus improving the system reliability. The oscillator frequency is set by an external RC network, and in this embodiment, it is set to 50kHz. The error amplifier compares the current setpoint with the current feedback value and outputs an error amplification signal to the PWM comparator. After comparison with the sawtooth wave by the PWM comparator, a PWM signal with a controlled duty cycle is output. When the current feedback value is lower than the setpoint, the output of the error amplifier increases, and the PWM duty cycle increases; when the current feedback value is higher than the setpoint, the output of the error amplifier decreases, and the PWM duty cycle decreases.

[0047] The PWM duty cycle limiting circuit uses dual comparators to form upper and lower limit circuits, limiting the PWM duty cycle to the range of 5%-90%. The lower limit of 5% ensures that the power drive module 9 can still maintain normal operation under the minimum conduction time, avoiding abnormal increase in switching losses of power devices under extremely short pulses. The upper limit of 90% provides sufficient turn-off time for the power devices and magnetic components of the power drive module 9, preventing the core from saturating or the power devices from overheating due to excessively high duty cycle.

[0048] In this embodiment, the power drive module 9 is located between the drive control module 4 and the interlock module 5. Its input terminal receives the PWM control signal output by the drive control module 4, and its output terminal is connected to the permanent magnet switch coil 6 via the interlock module 5. The power drive module 9 independently undertakes the functions of power amplification and power conversion. It chops the DC bus voltage provided by the power supply module 1 into a high-frequency pulse voltage under the control of the PWM control signal and applies it to both ends of the permanent magnet switch coil 6, driving the coil current to change according to the set waveform. By separating the signal-level drive control module 4 and the power-level power drive module 9, the control circuit and the power circuit are electrically isolated, avoiding interference from high voltage and high current in the power circuit to the control signal.

[0049] In this embodiment, the opening and closing interlock module 5 is located between the power drive module 9 and the permanent magnet switch coil 6. That is, the power output terminal of the power drive module 9 first enters the opening and closing interlock module 5, and after being controlled by the hardware interlock logic, it is then connected to the opening coil 7 and the closing coil 8 respectively.

[0050] In this embodiment, the permanent magnet switch adopts a single-coil permanent magnet mechanism, that is, the opening and closing of the switch share the same coil. The opening or closing operation is achieved by changing the current direction in the coil. The opening coil 7 and the closing coil 8 are actually two current directions of the same coil. The H-bridge power conversion circuit of the power drive module 9 achieves opening and closing control by switching the current direction.

[0051] The coil parameters are as follows: coil resistance is 2.5Ω, coil inductance is 6.8mH, and number of turns is 380; the permanent magnet is made of neodymium iron boron material with coercivity ≥900kA / m; the rated drive current of the coil is 8A, and the maximum allowable current is 12A.

[0052] In the embodiments, such as Figure 2 As shown, the equivalent constant current control method is performed according to the following steps: Step S1: System Initialization and Parameter Configuration After the system is powered on, the main control module 2 performs initialization operations to complete the parameter configuration of the drive time threshold and constant current target value. After initialization, the main control module 2 is in standby mode, waiting for external closing instructions.

[0053] Step S2: Drive enable and PWM closed-loop control When the external closing command arrives, the main control module 2 confirms that the opening status is normal and the power drive module 9 is in normal status. Then, it outputs drive enable to the drive control module 4 and the power drive module 9 to start outputting the PWM signal.

[0054] After the drive control module 4 is enabled, the current detection module 3 is connected in series in the output circuit of the power drive module 9 to collect the current signal flowing through the permanent magnet switch coil 6 in real time, and send the current feedback value to the input terminal of the error amplifier of the drive control module 4. The error amplifier compares the current set value with the current feedback value, outputs the error amplification signal to the PWM comparator, and outputs a PWM signal with controlled duty cycle after comparison with the sawtooth wave.

[0055] The PWM control signal serves as the input control signal for the power drive module 9, controlling the switching of the power devices inside the power drive module 9. It chops the DC bus voltage provided by the power supply module 1 into a high-frequency pulse voltage and applies it to the permanent magnet switch coil 6. When the current feedback value is lower than the set value, the PWM duty cycle increases; when the current feedback value is higher than the set value, the PWM duty cycle decreases, thereby achieving closed-loop constant current regulation of the coil current.

[0056] Step S2-1: Start the driver timing synchronization When the drive control module 4 is enabled, the main control module 2 starts timing and records the drive duration; during the current establishment phase, the current of the permanent magnet switch coil 6 is quickly adjusted according to the PWM duty cycle; during the constant current drive phase, the drive control module 4 performs closed-loop regulation and continuously adjusts the current of the permanent magnet switch coil 6 according to the PWM duty cycle; during the holding phase, the current of the permanent magnet switch coil 6 is kept constant to ensure that the moving iron core is reliably held.

[0057] Step S2-2: Synchronous Detection of Working Status and Fault Diagnosis During the continuous drive enable period, the main control module 2 synchronously detects the working status of the permanent magnet switch coil 6 and determines whether the opening and closing signals overlap through the hardware logic circuit of the opening and closing interlock module 5, ensuring that the path from the power output stage to the coil is controlled by the interlock logic at the hardware level.

[0058] If no action signal is detected in the corresponding drive coil after enabling, the main control module 2 determines the fault type based on whether the interlock protection is effective: if the interlock protection is effective, it indicates that there is overlap between the opening and closing signals, the hardware interlock circuit has cut off the power path, and the interlock protection is indicated by the indicator light; if the interlock protection is not effective but the coil does not act, it is determined to be a hardware fault, and the fault alarm is indicated by the indicator light.

[0059] Step S3: Timed shutdown and driver termination When the main control module 2 reaches the preset drive time threshold, the overflow interrupt service routine automatically clears the drive enable signal. This interrupt has the highest priority and is not affected by the main program execution state, ensuring that the drive time will not exceed the limit. After the drive enable signal is cleared, the PWM output of the drive control module 4 stops, all power drive modules 9 are turned off, and the current of the permanent magnet switch coil 6 drops to zero, completing this drive operation.

[0060] Based on the specific steps of the permanent magnet switch drive control method based on equivalent constant current technology in the above embodiments, the system operating timing and protection mechanism will be further explained below: A: Normal working sequence Taking a complete closing action as an example, the system's operating timing is as follows: At t=0ms: An external closing command is sent. The main control module 2 confirms that the opening status is normal and the power drive module 9 is normal. It outputs the closing drive enable to the drive control module 4 and the power drive module 9, starts outputting the PWM signal and starts the timing.

[0061] t=0-2ms stage: soft start stage, the PWM duty cycle output by drive control module 4 increases by %, the power drive module 9 chopper outputs, and the current of permanent magnet switch coil 6 increases.

[0062] t=2-5ms stage: Current establishment stage, the PWM duty cycle is adjusted within the coarse adjustment range, so that the effective value of the output voltage of the power drive module 9 changes accordingly, and the moving iron core of the permanent magnet switch coil 6 begins to move.

[0063] t=5-50ms stage: constant current drive stage, drive control module 4 performs closed-loop regulation, PWM duty cycle is adjusted within the pull-in / adjustment range, so that power drive module 9 outputs the corresponding chopping voltage, and the moving iron core of permanent magnet switch coil 6 accelerates to the end position.

[0064] t=50-65ms stage: holding stage, the moving iron core has reached the closed position, the power drive module 9 continues to output, ensuring that the moving iron core of the permanent magnet switch coil 6 is reliably held.

[0065] During the t=65-100ms stage: To ensure reliable closing, constant current drive is maintained and the power drive module 9 continues to work, providing a margin to overcome possible mechanical resistance.

[0066] At t=100ms: the timer overflow interrupt is triggered, the main control module 2 clears the drive enable signal, the PWM output of the drive control module 4 stops, the power drive module 9 is completely turned off, and the current of the permanent magnet switch coil 6 drops to zero through the freewheeling diode.

[0067] t=100-120ms stage: Close remote signaling point confirmation stage, main control module 2 confirms successful closing action.

[0068] B: Protection Mechanism This system has multiple protection mechanisms in place, as detailed below: Overcurrent protection: When the current detection module 3 detects that the coil current exceeds the limit, the overcurrent protection comparator flips, and the overcurrent signal is simultaneously sent to the fault synthesis circuit of the drive control module 4 and the isolation drive circuit of the power drive module 9. The fault synthesis circuit of the drive control module 4 blocks the PWM signal output to the power drive module 9; at the same time, the isolation drive circuit of the power drive module 9 also receives the overcurrent signal. This dual shutdown path ensures the absolute reliability of the overcurrent protection.

[0069] Drive time limit protection: Implemented by the TIM2 hardware timer of the main control module 2. After the drive duration reaches the threshold, the drive enable signal is forcibly turned off, and the power drive module 9 is turned off at the same time. The timer interrupt has the highest priority and is not affected by the main program execution status.

[0070] Hardware interlock protection: The opening and closing interlock module 5 ensures that the opening and closing power paths cannot be simultaneously connected, thus physically eliminating the possibility of a short circuit path being formed at the output of the power drive module 9 through the external coil circuit.

[0071] Over-temperature protection for power devices: The power drive module 9 has a built-in temperature detection. When the power device is at a high temperature, the status feedback circuit sends an over-temperature signal to the main control module 2. The main control module 2 immediately shuts down the drive enable, and at the same time, the fault integration circuit hardware blocks the PWM output until the temperature drops to a safe range.

[0072] Undervoltage lockout protection: The drive power supply circuit of the power drive module 9 is equipped with an undervoltage lockout function. When the drive power supply voltage is lower than the undervoltage threshold, the isolation drive circuit automatically blocks the output to prevent the power device from overheating and being damaged due to increased on-resistance under undervoltage conditions.

[0073] Watchdog protection: The main control module 2 has a built-in independent watchdog IWDG. When the main program loop exceeds the set time and the watchdog is not fed, the main control module 2 will be automatically reset. During the reset process, all output pins of the main control module 2 are configured to a high impedance state by hardware. After the reset, the default is floating input mode. The drive control module 4 and the power drive module 9 will be automatically shut down due to the loss of a valid drive enable signal to prevent the program from running away and causing loss of control.

[0074] In summary, the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Based on the above description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of the present invention is not limited to the contents of the specification; all equivalent variations and modifications of the shape, structure, features, and spirit described within the scope of the claims should be included within the scope of the claims.

Claims

1. A permanent magnet switch drive control method based on equivalent constant current technology, characterized in that, Includes the following steps: S1: The system is powered on, and the main control module (2) performs initial parameter configuration to complete the initialization of the drive time and constant current target value; S2: Enable the drive control module (4). The drive control module (4) automatically adjusts the duty cycle through PWM closed-loop control based on the coil current collected in real time by the current detection module (3) so that the drive current is maintained within the set constant current threshold range. S3: While enabling the drive control module (4), the main control module (2) starts the internal timer, records the drive duration, and synchronously detects the working status of the drive coil. It then uses the hardware interlock circuit to determine whether the opening and closing signals overlap. S4: When the timer inside the main control module (2) reaches the preset drive time threshold, the drive control module (4) is turned off and the power output is stopped.

2. The permanent magnet switch drive control method based on equivalent constant current technology according to claim 1, characterized in that: The PWM closed-loop control adopts a segmented PWM strategy: During the startup phase, a first duty cycle is used to quickly build up the current, and during the steady-state phase, a second duty cycle is used to maintain constant current output, wherein the first duty cycle is greater than the second duty cycle.

3. The permanent magnet switch drive control method based on equivalent constant current technology according to claim 1, characterized in that: The preset drive time threshold is 100ms, and the constant current target value is preset according to the parameters of the permanent magnet switch coil block (6).

4. The permanent magnet switch drive control method based on equivalent constant current technology according to claim 1, characterized in that: In step S3: If no action signal is detected in the corresponding drive coil after enabling, the fault type is determined based on whether the hardware interlock protection is effective: If the interlock protection is active, it is determined that the interlock has started; if the interlock protection is not active, it is determined that there is a hardware failure, and the driving result is indicated by the indicator light.

5. The permanent magnet switch drive control method based on equivalent constant current technology according to claim 1, characterized in that, It also includes a status feedback step: The system determines whether the opening and closing action has been completed by checking the returned remote signaling points for the opening and closing status. If the action has not been completed, an alarm signal is issued.

6. A permanent magnet switch drive control system based on equivalent constant current technology, characterized in that, include: Power supply module (1) is used to convert a wide range of input voltages into a stable DC drive power supply; The main control module (2) is used to monitor the working status of each module, perform communication transmission and reception, execute control commands, and set constant current thresholds; The current detection module (3) is used to collect the current of the drive coil in real time and feed it back to the drive control module (4). The drive control module (4) is used to generate PWM signals to control the on / off state of the power devices and achieve equivalent constant current output through closed-loop regulation; The opening and closing interlock module (5) is used to ensure that the opening signal and the closing signal are not output simultaneously through a hardware interlock circuit.

7. A permanent magnet switch drive control system based on equivalent constant current technology according to claim 6, characterized in that: The power supply module (1) adopts a wide voltage input design and includes: AC / DC conversion circuits and DC / DC conversion circuits automatically identify the input voltage type and amplitude, supporting a wide input range of 100-260V AC and 80-300V DC.

8. A permanent magnet switch drive control system based on equivalent constant current technology according to claim 6, characterized in that: The drive control module (4) adopts PWM constant current control mode, and changes the PWM duty cycle by monitoring the magnitude of the drive current in real time to achieve equivalent constant power output; The PWM control frequency is 20kHz-100kHz.

9. A permanent magnet switch drive control system based on equivalent constant current technology according to claim 6, characterized in that: The split-and-combination interlock module (5) includes: hardware interlock circuit and software interlock logic; The hardware interlock circuit is implemented through logic gate circuits. When the opening signal and the closing signal are both valid, the hardware interlock circuit blocks the two drive outputs.

10. A permanent magnet switch drive control system based on equivalent constant current technology according to claim 6, characterized in that: The main control module (2) has a built-in drive start recording unit and drive time counting unit. When the drive duration reaches a preset threshold, the drive output is automatically turned off. The main control module (2) is also provided with a communication interface for communicating with the host computer, which is used to upload working status and receive control commands.

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