A control method and system of a roll-film motor and a storage medium

Abstract

The application provides a control method and system of a roll film motor and a storage medium, comprising: acquiring an excitation voltage value and an excitation current peak value, determining a motor electrical time constant according to the excitation voltage value and the excitation current peak value, and determining a target power upper limit according to the motor electrical time constant. In the starting stage, an exponential soft start PWM climbing curve is generated according to the motor electrical time constant, the motor power supply control circuit is controlled to be turned on according to the exponential soft start PWM climbing curve, the real-time current value output by the current monitoring circuit is collected, the real-time current value is compared with a preset current threshold to obtain a comparison result, the PWM duty cycle is adjusted according to the comparison result so that the real-time current value does not exceed the preset current threshold; in the stopping stage, the differential value of the real-time current value with respect to time is calculated, and when the differential value reaches a preset negative slope threshold, the PWM duty cycle is controlled to decrease to zero in an exponential decreasing manner, and the A phase and the B phase are short-circuited by controlling the motor driving commutation circuit. Low-impact and high-precision control in the whole operation cycle is realized.

Description

Technical Field

[0001] This application relates to the field of film winding motor control technology, and in particular to a control method, system and storage medium for a film winding motor. Background Technology

[0002] Roll-up film motors are widely used in agricultural greenhouses, shading systems, and other applications, requiring frequent starts and stops and withstanding significant load fluctuations. Currently, common control schemes for roll-up film motors often employ a combination of fixed-parameter PWM soft start and limit switch hard stop: during startup, the duty cycle is slowly increased at a preset slope, while during stop, the power supply is directly cut off by a mechanical limit switch. However, in practical applications, the winding parameters of different individual motors exhibit dispersion, and changes in ambient temperature can cause significant resistance shifts. Fixed-parameter soft start cannot match the actual electrical characteristics, easily generating large starting current surges that affect the lifespan of fuses and power devices. Simultaneously, the hard stop method relying on limit switches experiences severe impacts during high-speed motor operation, accelerating switch wear and causing stop position deviations due to the rebound effect, reducing the accuracy of film winding. Therefore, how to adaptively match motor characteristics during startup to suppress current surges and achieve smooth and accurate stop control during the stopping phase is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0003] To address the issues of high starting current surge and low stopping accuracy, this application employs adaptive electrical matching and dynamic current closed-loop regulation to achieve low-impact, high-precision control throughout the entire operating cycle. This application also provides a control method, system, and storage medium for a film-wound motor.

[0004] In a first aspect, a method for controlling a film winding motor is provided, the method comprising: The excitation voltage and peak excitation current of the motor power supply are obtained under the excitation of the probe pulse output by the MCU. The motor electrical time constant is determined based on the excitation voltage and peak excitation current. The target power limit for this operation is determined based on the motor electrical time constant. During the startup phase, an exponential soft-start PWM ramp-up curve is generated based on the motor electrical time constant. The motor power supply control circuit is turned on according to the exponential soft-start PWM ramp-up curve. The real-time current value output by the current monitoring circuit is collected in real time. The real-time current value is compared with a preset current threshold to obtain a comparison result. The PWM duty cycle is dynamically adjusted according to the comparison result to ensure that the real-time current value does not exceed the preset current threshold. During the stopping phase, the derivative of the real-time current value with respect to time is continuously calculated. When the derivative value reaches the preset negative slope threshold, the PWM duty cycle is controlled to decrease to zero in an exponential manner, and the motor drive commutation circuit is controlled to short-circuit phases A and B of the film winding motor.

[0005] In some embodiments, determining the motor electrical time constant based on the excitation voltage value and the peak excitation current includes: The ratio of the excitation voltage value to the peak value of the excitation current is used as the DC resistance value of the motor winding; The product of the rate of change of current during the duration of the probe pulse excitation and the DC resistance of the motor winding is used as the inductance estimate. The ratio of the estimated inductance value to the DC resistance value of the motor winding is used as the electrical time constant of the motor.

[0006] In some embodiments, generating the exponential soft-start PWM ramp-up curve based on the motor electrical time constant includes: The time constant factor of the exponentially rising function is used as the electrical time constant of the motor, and the soft start duration of the exponential soft start PWM ramp-up curve is determined according to a preset multiple of the time constant factor. Using the duration of the soft start as a time window, a time series consisting of multiple discrete time points is established within the time window, wherein the time interval between adjacent discrete time points of the time series is equal to the PWM control cycle of the MCU. For each discrete time point in the time series, the time value of the discrete time point is substituted into an exponentially increasing function with the motor electrical time constant as the time constant factor to calculate the target duty cycle corresponding to that discrete time point. The function value of the exponentially increasing function starts from zero and increases monotonically with the increase of the time value and gradually approaches the preset maximum duty cycle threshold. The discrete time points in the time series are associated with their respective target duty cycles and stored to generate an exponential soft-start PWM ramp-up curve containing the target duty cycle data for each PWM control cycle within the soft-start duration.

[0007] In some embodiments, dynamically adjusting the PWM duty cycle based on the comparison result to ensure that the real-time current value does not exceed the preset current threshold includes: The first real-time current value output by the current monitoring circuit in each PWM control cycle of the exponential soft-start PWM ramp-up curve is obtained, and the first real-time current value is subtracted from the preset current threshold to obtain the first current deviation value of the current cycle. The first current deviation value of the current cycle is used as the input of the PID closed-loop controller. After the PID closed-loop controller performs proportional, integral and derivative operations, it outputs the first duty cycle adjustment increment of the current cycle. The first duty cycle adjustment increment of the current cycle is superimposed with the first target duty cycle corresponding to the current PWM control cycle in the exponential soft-start PWM ramp-up curve to obtain the first dynamic correction duty cycle of the current cycle; The first dynamic correction duty cycle of the current cycle is used as the first actual control signal of the motor power supply control circuit in the current PWM control cycle to drive the motor power supply control circuit to conduct according to the first dynamic correction duty cycle, so as to adjust the first effective voltage output by the motor power supply to the motor drive commutation circuit. In the next PWM control cycle, the second real-time current value output by the current monitoring circuit is reacquired and the second current deviation value is recalculated to update the duty cycle adjustment increment. Based on the updated duty cycle adjustment increment, the target duty cycle corresponding to the next PWM control cycle in the exponential soft-start PWM ramp-up curve is corrected. This process is repeated until the real-time current value is not greater than the preset current threshold or the exponential soft-start PWM ramp-up curve is completed.

[0008] In some embodiments, controlling the PWM duty cycle to decrease to zero in an exponentially decreasing manner includes: The initial decreasing duty cycle is determined based on the difference between the preset negative slope threshold and the differential value. The motor electrical time constant is used as the time constant factor of the exponential decay function. The PWM duty cycle is controlled to decrease from the initial decreasing duty cycle to zero according to the exponential decay function.

[0009] In a second aspect, a control system for a film winding motor is provided, which executes the control method for a film winding motor described in the first aspect, the system comprising: The motor power supply and system power supply are isolated from each other, wherein the motor power supply is used to provide drive power for the film winding motor, and the system power supply is used to provide power to other component modules in the control system independently of the motor power supply; The voltage monitoring circuit has its input terminal connected across the back end of the fuse in the output circuit of the motor power supply and ground, and its output terminal connected to the MCU. It is used to collect the voltage signal at the back end of the fuse under the detection pulse output by the MCU, and transmit the voltage signal to the MCU so that the MCU can determine the excitation voltage value based on the voltage signal. The current monitoring circuit has its input terminal connected across the sampling resistor in the output circuit of the motor power supply, and its output terminal connected to the MCU. It is used to acquire the voltage difference signal across the sampling resistor under the excitation of the detection pulse output by the MCU, and transmit the voltage difference signal to the MCU so that the MCU can determine the peak value of the excitation current based on the voltage difference signal, and calculate the motor electrical time constant based on the excitation voltage value and the excitation current value. A motor power supply control circuit is connected in series between the rear end of the fuse and the motor drive commutation circuit. Its control terminal is connected to the MCU and is used to turn on or off according to the PWM drive signal output by the MCU during the startup phase. The duty cycle of the PWM drive signal changes periodically according to the exponential soft-start PWM ramp-up curve generated based on the motor electrical time constant. The MCU corrects the duty cycle of the current cycle according to the comparison result between the real-time current value fed back by the current monitoring circuit and the preset current threshold, so that the real-time current value does not exceed the preset current threshold. The motor drive steering circuit is connected between the output terminal of the motor power supply control circuit and the film winding motor, and includes a relay for switching the power supply polarity of phase A and phase B of the film winding motor according to the control signal of the MCU. The MCU is also used to calculate the derivative of the real-time current value with respect to time based on the real-time current value fed back by the current monitoring circuit during the stop phase. When the derivative value reaches the preset negative slope threshold, the PWM duty cycle is controlled to decrease to zero in an exponential manner, and the motor drive commutation circuit is controlled to short-circuit the A and B phases of the film winding motor.

[0010] In some embodiments, the system further includes: The communication module connected to the MCU is used to receive external control commands and send the status information of the MCU.

[0011] In some embodiments, the system further includes: A surge protection circuit is connected between the output terminal of the current monitoring circuit and the film winding motor to suppress surges in the film winding motor. An isolation relay is connected in series between the output terminal of the surge protection circuit and the film winding motor, and its control terminal is connected to the MCU to turn on or off the current loop of the film winding motor according to the control signal of the MCU. An isolation voltage reversal detection circuit is provided, with its input terminals connected to the output terminal of the motor drive steering circuit and the input terminal of the film winding motor, respectively, and its output terminal connected to the MCU. The circuit is used to transmit the comparison result between the output polarity of the motor drive steering circuit and the input polarity of the film winding motor to the MCU.

[0012] In some embodiments, the motor-driven steering circuit includes: A relay, wherein the relay includes a first coil, a first normally open contact, a first normally closed contact, a first common terminal, a second normally open contact, a second normally closed contact, and a second common terminal; The first end of the first coil is connected to the first control signal output terminal of the MCU, and the second end of the first coil is grounded. The first common terminal is connected to the output terminal of the motor power supply control circuit, the first normally open contact is connected to the A-phase power supply input terminal of the film winding motor, and the first normally closed contact is connected to the B-phase power supply input terminal of the film winding motor. The second common terminal is connected to the output terminal of the motor power supply control circuit, the second normally open contact is connected to the B-phase power supply input terminal of the film winding motor, and the second normally closed contact is connected to the A-phase power supply input terminal of the film winding motor. The MCU controls the relay to engage via a positive control signal output from the first control signal output terminal, so that the output terminal of the motor power supply control circuit simultaneously forms a first polarity connection with both the A-phase power supply input terminal and the B-phase power supply input terminal. The MCU controls the relay to reset through the reverse control signal output from the first control signal output terminal, so that the output terminal of the motor power supply control circuit simultaneously forms a second polarity connection with the A-phase power supply input terminal and the B-phase power supply input terminal.

[0013] Thirdly, a computer-readable storage medium is provided having a computer program stored thereon that can run on a processor, wherein when executed by the processor, the computer program implements a control method for a film winding motor as described in the first aspect.

[0014] The present invention has at least the following beneficial effects: Firstly, by detecting the electrical time constant of the motor in real time through the detection pulse, an exponential soft-start curve matching the dynamic characteristics of the motor is generated. Then, a cycle-by-cycle current closed-loop correction is introduced during the startup process to precisely clamp the actual current within the safety threshold, effectively suppressing startup shock and extending the life of fuses and power devices.

[0015] Secondly, during the stopping phase, the trend of reaching the stop position is identified in advance based on the negative slope threshold of the current derivative, triggering exponentially decreasing soft stop and winding short-circuit damping braking, so that the motor completes the main deceleration before contacting the limit switch, reducing rigid impact, reducing mechanical wear and improving the repeatability accuracy of the stopping position.

[0016] Third, the motor power supply and the system power supply are isolated from each other, ensuring that the MCU and monitoring circuit can still work stably and reliably complete fault detection and protection actions when the motor circuit fails. Combined with multiple protections such as voltage and current monitoring and polarity detection, the system's safety redundancy and long-term operational reliability under complex working conditions are improved. Attached Figure Description

[0017] Figure 1 This is a block diagram of a control system for a film winding motor provided in Embodiment 1 of this application.

[0018] Figure 2This is a schematic diagram of the voltage monitoring circuit provided in Embodiment 1 of this application.

[0019] Figure 3 This is a schematic diagram of the motor power supply control circuit provided in Embodiment 1 of this application.

[0020] Figure 4 This is a schematic diagram of the current monitoring circuit provided in Embodiment 1 of this application.

[0021] Figure 5 This is a schematic diagram of the motor drive commutation circuit provided in Embodiment 1 of this application.

[0022] Figure 6 This is a block diagram of a control method for a film winding motor provided in this application. Detailed Implementation

[0023] To better understand the purpose, technical solutions, and advantages of this application, it has been described and illustrated below with reference to the accompanying drawings and embodiments. However, those skilled in the art should understand that this application can be implemented without these details. It will be apparent to those skilled in the art that various modifications can be made to the embodiments disclosed in this application, and the general principles defined in this application can be applied to other embodiments and application scenarios without departing from the principles and scope of this application. Therefore, this application is not limited to the illustrated embodiments, but is consistent with the broadest scope claimed in this application.

[0024] Example 1: Figure 1 This is a block diagram of a control system for a film winding motor provided in this application. Figure 1As shown, a control system for a film-winding motor includes isolated motor power supplies and system power supplies, a voltage monitoring circuit, a motor power supply control circuit, a current monitoring circuit, a motor drive and steering circuit, and an MCU. The motor power supply provides drive power to the film-winding motor, while the system power supply provides power to other modules in the control system independently of the motor power supply. The input of the voltage monitoring circuit is connected between the back end of a fuse connected in series in the output circuit of the motor power supply and ground. The output of the voltage monitoring circuit is connected to the MCU. It acquires the voltage signal at the back end of the fuse under the detection pulse output by the MCU and transmits the voltage signal to the MCU so that the MCU can determine the excitation voltage value. The input of the current monitoring circuit is connected across a sampling resistor in the output circuit of the motor power supply. The output of the current monitoring circuit is connected to the MCU. It acquires the voltage difference signal across the sampling resistor under the excitation pulse output by the MCU and transmits the voltage difference signal to the MCU so that the MCU can determine the peak value of the excitation current and calculate the motor electrical time constant based on the excitation voltage and excitation current values. The motor power supply control circuit is connected in series between the fuse and the motor drive commutation circuit. The control terminal of the motor power supply control circuit is connected to the MCU, used to turn the PWM drive signal on or off during the startup phase based on the MCU output. The duty cycle of the PWM drive signal changes periodically according to an exponential soft-start PWM ramp-up curve generated based on the motor's electrical time constant. The MCU adjusts the duty cycle of the current cycle based on the comparison between the real-time current value fed back by the current monitoring circuit and a preset current threshold, ensuring that the real-time current value does not exceed the preset current threshold. The motor drive steering circuit is connected between the output terminal of the motor power supply control circuit and the winding motor, including a relay used to switch the power supply polarity of phases A and B of the winding motor according to the MCU's control signal. During the stopping phase, the MCU also calculates the derivative of the real-time current value with respect to time based on the real-time current value fed back by the current monitoring circuit. When the derivative reaches a preset negative slope threshold, the PWM duty cycle is controlled to decrease exponentially to zero, and the motor drive commutation circuit is controlled to short-circuit phases A and B of the winding motor.

[0025] The motor power supply provides drive power to the film winding motor, while the system power supply provides independent power to other components in the control system, such as the MCU. The two are isolated from each other, which can be achieved by using two independent DC power supply modules or by using an isolated DC-DC converter. This isolation design ensures that when the motor power supply circuit experiences faults such as blown fuses, short circuits, or voltage drops, the system power supply can still maintain a stable output, allowing the MCU and other monitoring circuits to continue operating reliably for fault detection and reporting.

[0026] Figure 2 This is a schematic diagram of the voltage monitoring circuit provided in Embodiment 1 of this application. Figure 2As shown, a fuse F1 is connected in series at the positive output terminal of the motor power supply. A voltage divider circuit consisting of resistors R1 and R2 is connected between the rear end of fuse F1 (the end not directly connected to the positive terminal of the motor power supply) and ground. One end of resistor R1 is connected to the rear end of fuse F1, and the other end of resistor R1 is connected to one end of resistor R2 and the analog-to-digital converter (ADC) pin of the MCU. The other end of resistor R2 is grounded. The MCU's ADC pin can obtain the voltage value at the rear end of fuse F1 in real time by acquiring the voltage divider signal at the connection point of resistors R1 and R2. Specifically, the drive voltage output from the motor power supply is applied to the series branch composed of resistors R1 and R2 after passing through fuse F1. The voltage across resistor R2 is the voltage divider signal acquired by the MCU's ADC pin. Since the resistance ratio of resistors R1 and R2 is fixed, the MCU can obtain the actual voltage value at the rear end of fuse F1 based on the acquired voltage divider signal value and this voltage divider ratio, thus determining that there is a power supply abnormality in the motor power supply circuit. If the voltage value is lower than the preset voltage threshold, it is determined that there is a power supply abnormality in the motor power supply circuit, such as the fuse F1 has blown or the upstream power supply is missing.

[0027] Figure 3 This is a schematic diagram of the motor power supply control circuit provided in Embodiment 1 of this application. Figure 3 As shown, the motor power supply control circuit includes a switching circuit composed of resistors R3 and R4, and MOSFETs Q1 and Q2. The positive terminal of the motor power supply is connected to the source of MOSFET Q1, and the drain of MOSFET Q1 serves as the positive output terminal for the motor drive power supply, connected to the subsequent motor drive steering circuit. Resistor R3 connects the source and gate of MOSFET Q1. The gate of MOSFET Q1 is connected to the drain of MOSFET Q2, the source of MOSFET Q2 is grounded, and the gate of MOSFET Q2 is connected to the first control signal output terminal of the MCU via resistor R4. Specifically, when the MCU receives the film winding start command, the first control signal output terminal outputs a high level. After current limiting by resistor R4, it drives MOSFET Q2 to conduct, pulling the gate potential of MOSFET Q1 to a low level. At this time, the bias voltage difference required for conduction is formed between the source and gate of MOSFET Q1, causing MOSFET Q1 to saturate and conduct. The power supply voltage of the motor is stably output to the subsequent circuit through MOSFET Q1, providing drive power for the film winding motor. When the MCU receives a stop command, or detects a fault condition through the voltage monitoring circuit and current monitoring circuit, the first control signal output switches to a low level, MOSFET Q2 is turned off, and the gate bias of MOSFET Q1 disappears, thus turning off as well. This immediately cuts off the motor power supply output path, stopping the film winding motor. Thanks to the mutual isolation design between the motor power supply and the system power supply, even if there is a short circuit or fuse blown in the motor power supply circuit, the system power supply can still provide a stable power supply to the MCU, ensuring that the MCU can reliably output the shutdown control signal and preventing the fault from spreading.

[0028] During the operation of the motor power supply circuit, the operating current of the circuit is collected in real time through the current monitoring circuit to provide data basis for overcurrent fault protection. Figure 4 This is a schematic diagram of the current monitoring circuit provided in Embodiment 1 of this application. Figure 4 As shown, the current monitoring circuit includes operational amplifier U1, resistors R5, R6, and R7. Resistor R5 is connected across the output terminal of operational amplifier U1 and its inverting input terminal. One end of resistor R6 is connected to the inverting input terminal of operational amplifier U1, and the other end is grounded. Resistors R5 and R6 together form the negative feedback network of operational amplifier U1, used to set the amplification factor of the differential signal, which is (R5+R6) / R6. Resistor R7 is connected in series between the output terminal of operational amplifier U1 and the analog-to-digital converter (ADC) pin of the MCU, serving as a current limiting and signal transmission resistor to prevent damage to the MCU's ADC input pin due to overvoltage or overcurrent. It also forms a filter network with the input impedance of the MCU's internal ADC sample-and-hold circuit to reduce high-frequency noise. Specifically, after being conditioned by operational amplifier U1 to a preset amplification factor to adapt to the MCU's sampling voltage range, the signal is transmitted to the MCU's analog-to-digital converter pin via resistor R7. After performing analog-to-digital conversion on the analog voltage signal, the MCU calculates the real-time current value of the current motor power supply circuit by combining the resistance value of the sampling resistor and the amplification factor of the operational amplifier. When the real-time current value exceeds the preset overcurrent threshold, the MCU determines that a stalled rotor or short-circuit fault has occurred in the circuit, immediately cuts off the motor power supply, and reports the fault information to the upper layer through the communication module, thereby achieving rapid circuit protection.

[0029] Based on the on / off control of the motor power supply path and real-time monitoring of the operating current, the system completes the switching of the forward and reverse rotation direction of the film winding motor through the motor drive commutation circuit. The circuit adopts a simplified architecture with a single relay and a transistor drive, which reduces hardware costs while ensuring the stability and reliability of the commutation action. Figure 5 This is a schematic diagram of the motor drive steering circuit provided in Embodiment 1 of this application. Figure 5As shown, the motor drive steering circuit includes a relay, wherein the relay includes a first coil, a first normally open contact, a first normally closed contact, a first common terminal, a second normally open contact, a second normally closed contact, and a second common terminal. The first end of the first coil is connected to the first control signal output terminal of the MCU, and the second end of the first coil is grounded. The first common terminal is connected to the output terminal of the motor power supply control circuit, the first normally open contact is connected to the A-phase power supply input terminal of the film winding motor, and the first normally closed contact is connected to the B-phase power supply input terminal of the film winding motor. The second common terminal is connected to the output terminal of the motor power supply control circuit, the second normally open contact is connected to the B-phase power supply input terminal of the film winding motor, and the second normally closed contact is connected to the A-phase power supply input terminal of the film winding motor. The MCU controls the relay to engage via a positive control signal output from the first control signal output terminal, causing the output terminal of the motor power supply control circuit to simultaneously form a first polarity connection with both the A-phase and B-phase power supply input terminals. The MCU controls the relay to reset via a reverse control signal output from the first control signal output terminal, causing the output terminal of the motor power supply control circuit to simultaneously form a second polarity connection with both the A-phase and B-phase power supply input terminals.

[0030] The motor drive steering circuit also includes transistor Q3, resistor R8, and diode D1. The base of transistor Q3 is connected to the second control signal output terminal of the MCU. The collector of transistor Q3 is connected to one end of resistor R8 and the anode of diode D1, and the emitter of transistor Q3 is grounded. The other end of resistor R8 and the cathode of diode D1 are connected to one end of the relay coil, and the other end of the relay coil is grounded. The relay includes two sets of linked contact components: the first common terminal is connected to the positive terminal of the motor drive power supply, the first normally open contact is connected to the A-phase power supply input terminal of the winding motor, and the first normally closed contact is connected to the B-phase power supply input terminal of the winding motor; the second common terminal is connected to the negative terminal of the motor drive power supply, the second normally open contact is connected to the B-phase power supply input terminal of the winding motor, and the second normally closed contact is connected to the A-phase power supply input terminal of the winding motor.

[0031] Specifically, when the MCU outputs a positive control signal, the first control signal output terminal outputs a high level and applies it to the base of transistor Q3, causing transistor Q3 to saturate and conduct. The relay coil forms a complete current loop and is energized and energized. The two sets of linked normally open contacts close synchronously, and the normally closed contacts open synchronously. At this time, the positive terminal of the motor drive power supply is connected to the A-phase power supply input terminal of the winding motor, and the negative terminal of the motor drive power supply is connected to the B-phase power supply input terminal of the winding motor. The winding motor rotates in the forward direction. When the MCU outputs a reverse control signal, the first control signal output terminal switches to a low level. The base bias of transistor Q3 disappears and enters the cutoff state. The relay coil is de-energized and begins to reset. At this time, the reverse induced electromotive force generated by the sudden current change in the coil can form a freewheeling discharge circuit through diode D1, preventing the peak voltage from breaking down transistor Q3 or interfering with the preceding control circuit. After the relay resets, both sets of normally closed contacts close synchronously, and the normally open contacts open synchronously. The positive terminal of the motor drive power supply is connected to the B-phase power input terminal of the film winding motor, and the negative terminal of the motor drive power supply is connected to the A-phase power input terminal of the film winding motor. The polarities of the two phase power supplies of the film winding motor are completely interchanged, and it rotates in opposite directions. The complete switching of the polarities of the two phase power supplies of the motor can be achieved with only a single double-pole double-throw relay. Combined with the transistor drive circuit, the load capacity of the MCU control signal is improved. While realizing bidirectional film winding control, the hardware topology is simplified, potential failure points are reduced, and it is compatible with the dual power supply isolation architecture, further improving the reliability of system operation.

[0032] Example 2: Based on the disclosure in Embodiment 1, a control system for a film winding motor further includes a communication module connected to an MCU, used to receive external control commands and send status information from the MCU. This facilitates the MCU reporting relevant fault information to the upper-level system at any time via the communication module.

[0033] Example 3: Preferably, based on the disclosure in Embodiment 1, a control system for a roll-up motor further includes a surge protection circuit, an isolation relay, and an isolation voltage reversal detection circuit. The surge protection circuit is connected between the output of the current monitoring circuit and the roll-up motor to suppress surges in the roll-up motor. The isolation relay is connected in series between the output of the surge protection circuit and the roll-up motor, and its control terminal is connected to the MCU to turn the current loop of the roll-up motor on or off according to the control signal from the MCU. The input of the isolation voltage reversal detection circuit is connected to the output of the motor drive steering circuit and the input of the roll-up motor, respectively, and its output is connected to the MCU to transmit the comparison result between the output polarity of the motor drive steering circuit and the input polarity of the roll-up motor to the MCU. By adding a surge protection circuit between the current monitoring circuit and the roll-up motor, surge impacts caused by motor start-up and shutdown, as well as external lightning strikes, are effectively suppressed, reducing damage to the control system due to high-voltage spikes. Simultaneously, the series-connected isolation relay physically disconnects the motor current loop after the commutation circuit stops outputting, forming electrical isolation from external cables, further blocking the surge current intrusion path and improving survivability in harsh outdoor environments. Furthermore, an isolation voltage reversal detection circuit is introduced to compare the output polarity of the commutation circuit with the actual input polarity of the motor in real time. If the directions are inconsistent, the system will stop immediately and report the fault, reducing malfunctions caused by relay contact sticking or abnormal control signals. Thus, based on the dual power supply isolation and fault monitoring in Example 1, the system's anti-interference capability, safety redundancy, and fault self-diagnosis capability are enhanced, improving the long-term operational reliability and protection level of the film winding control system in complex application scenarios.

[0034] Example 4: Preferably, based on the disclosure in Embodiment 1, a control system for a film-winding motor further includes a communication module connected to an MCU, a surge protection circuit, an isolation relay, and an isolation voltage reversal detection circuit. The communication module receives external control commands and sends status information to the MCU. The surge protection circuit is connected between the output of the current monitoring circuit and the film-winding motor to suppress surges in the film-winding motor. The isolation relay is connected in series between the output of the surge protection circuit and the film-winding motor, and its control terminal is connected to the MCU to turn the current loop of the film-winding motor on or off according to the control signal from the MCU. The input of the isolation voltage reversal detection circuit is connected to the output of the motor drive steering circuit and the input of the film-winding motor, respectively, and its output is connected to the MCU to transmit the comparison result between the output polarity of the motor drive steering circuit and the input polarity of the film-winding motor to the MCU.

[0035] Example 5: Figure 6 This is a block diagram of a control method for a film-winding motor provided in this application. The control method for a film-winding motor is applied to the control system of a film-winding motor in any one of Embodiments 1 to 4. Figure 6 As shown, a control method for a film winding motor includes the following steps: Step S100: Obtain the excitation voltage and peak excitation current of the motor power supply under the excitation of the probe pulse output by the MCU, determine the motor electrical time constant based on the excitation voltage and peak excitation current, and determine the target power limit for this operation based on the motor electrical time constant.

[0036] Before each start-up of the film winding motor, a load characteristic pre-identification operation is automatically performed. Specifically, after receiving the film winding start command, the MCU does not immediately turn on the motor power supply control circuit. Instead, it outputs a probe pulse with a fixed duty cycle and fixed duration through its PWM output port. This probe pulse is amplified by the MOSFET Q1 in the motor power supply control circuit and applied to the winding terminals of the film winding motor. During the probe pulse output, the voltage monitoring circuit continuously collects the voltage signal at the back end of the fuse and transmits it to the MCU's analog-to-digital conversion pin. The MCU performs analog-to-digital conversion on the collected voltage signal, reads the transient voltage value, and records this transient voltage value as the excitation voltage value of the motor power supply under the excitation pulse. Simultaneously, the current monitoring circuit collects the current signal flowing through the sampling resistor in real time. This current signal is amplified by the operational amplifier U1 and transmitted to the MCU's analog-to-digital conversion pin. During the probe pulse duration, the MCU reads the current sampling value multiple times at a sampling rate higher than the PWM frequency and extracts the peak value from the multiple current sampling values ​​as the excitation current peak value. Preferably, the duty cycle of the probe pulse is set to 5%, and the duration is set to 100 μs. This setting allows the probe pulse to apply sufficient electrical excitation to the motor windings to obtain effective electrical response parameters without causing substantial mechanical rotation in the film-winding motor. After obtaining the excitation voltage and peak excitation current values, these two values ​​are used as the basic input data for subsequent calculations of the motor's electrical time constant. Before the motor starts, a non-operating probe pulse is given to obtain the motor's rated parameters, i.e., the motor model, as the basic value, enabling the control system to dynamically match different motors.

[0037] Before actual startup, in order to quantitatively obtain the electrical response characteristics of the motor windings, the collected excitation voltage and peak excitation current values ​​need to be further processed to determine the motor's electrical time constant. This time constant is the basis for subsequently generating the exponential soft-start PWM ramp-up curve and achieving low-impact startup. Determining the motor's electrical time constant based on the excitation voltage and peak excitation current includes the following steps: Step S101: The ratio of the excitation voltage value to the peak value of the excitation current is used as the DC resistance value of the motor winding.

[0038] Step S102: The product of the rate of change of current during the duration of the probe pulse excitation and the DC resistance of the motor winding is used as the inductance estimate.

[0039] Step S103: The ratio of the estimated inductance value to the DC resistance value of the motor winding is used as the electrical time constant of the motor.

[0040] Specifically, due to the extremely short duration of the probe pulse, the motor rotor has not yet undergone substantial rotation. At this time, the back electromotive force of the motor winding is approximately zero. Therefore, the relationship between the voltage applied to the motor winding terminals and the current flowing through the winding can be equivalent to a purely resistive load. The MCU divides the acquired excitation voltage value by the peak excitation current value, i.e., the DC resistance value of the motor winding = excitation voltage value / peak excitation current value. This DC resistance value of the motor winding reflects the internal resistance state of the motor winding at the current temperature, providing a basic parameter for subsequent electrical time constant calculation. Preferably, during the calculation process, to improve the estimation accuracy, the MCU can perform median filtering on the voltage and current acquired by the analog-to-digital conversion pin before using them.

[0041] During the entire duration of the probe pulse, from its rising edge to its falling edge, the current signal output by the current monitoring circuit is continuously sampled at a sampling rate higher than the PWM frequency, recording a discrete data sequence of current value changes over time. Then, the least squares method is used to linearly fit this data sequence, obtaining the slope value of the current change over time, which is the rate of change of current. Considering the approximately linear increase of current during the probe pulse duration, the calculated rate of change of current is multiplied by the determined DC resistance value of the motor winding to obtain the inductance estimate, i.e., inductance estimate = motor winding DC resistance value * rate of change of current * probe pulse duration. This product reflects the inductive impedance effect of the motor winding due to the establishment of magnetic flux at the moment of energization, and can accurately estimate the equivalent inductance value of the winding.

[0042] Finally, the estimated inductance value is divided by the DC resistance of the motor winding to obtain the motor electrical time constant. This motor electrical time constant reflects the response speed of the motor winding current rising from zero to a stable value, and can characterize the motor's electrical dynamic characteristics. Since this motor electrical time constant is obtained in real time through a single probe pulse, it can effectively reflect the actual electrical state of the motor winding under the current operating conditions, including resistance shifts caused by temperature changes and inductance changes caused by winding aging, and has adaptive properties. The calculated motor electrical time constant is temporarily stored in an internal register, providing a basis for all subsequent power control within this operating cycle. The entire process can quickly complete the quantitative identification of the motor electrical time constant with a single probe pulse, without additional hardware, and is unaffected by the motor load state. It can adaptively extract electrical parameters for different individual motor differences and different environmental conditions, providing a reliable quantitative basis for the accurate generation of subsequent exponential soft-start PWM ramp-up curves and constant power control, thereby effectively reducing start-up impact and improving control accuracy and adaptability.

[0043] After quantitatively identifying the motor's electrical time constant, the load level for the current operating condition is determined based on this parameter characterizing the motor's electrical dynamics. Furthermore, the target power upper limit for this operation is determined, providing a quantitative benchmark for power constraint control throughout the subsequent operating cycle. The MCU pre-stores a mapping relationship between the motor's electrical time constant and the load level, established through calibration tests on the same model of motor. This mapping relationship divides the range of the motor's electrical time constant into three continuous intervals: light load, medium load, and heavy load. Each interval corresponds to a set of preset benchmark power upper limits. The motor's electrical time constant obtained in this real-time identification is substituted into the preset mapping relationship for interval matching to determine the load level of the current motor and load, and the corresponding benchmark power upper limit value is retrieved. Based on this, the reference power upper limit is corrected in real time by combining the excitation voltage value collected under the current detection pulse excitation. Specifically, the ratio of the excitation voltage value to the motor's rated voltage is used as the voltage correction coefficient. The reference power upper limit is multiplied by this voltage correction coefficient to obtain the target power upper limit adapted to the current real-time power supply status of the motor. This target power upper limit is written into a dedicated register inside the MCU as the upper limit constraint parameter for power closed-loop regulation within this operating cycle. By dynamically matching and correcting the target power upper limit based on the real-time identified motor electrical time constant, it can adapt to the individual differences of different motors and load conditions, effectively reducing the starting shock or insufficient load adaptation problems caused by fixed power parameters, and improving the accuracy of operating condition adaptation and operational stability.

[0044] In step S200, during the startup phase, an exponential soft-start PWM ramp-up curve is generated based on the motor electrical time constant. The motor power supply control circuit is turned on according to the exponential soft-start PWM ramp-up curve, and the real-time current value output by the current monitoring circuit is collected in real time. The real-time current value is compared with a preset current threshold to obtain a comparison result. The PWM duty cycle is dynamically adjusted according to the comparison result to ensure that the real-time current value does not exceed the preset current threshold.

[0045] After quantitatively identifying the motor's electrical time constant and locking the target power limit for this operation, the system enters the startup phase. To reduce the current surge caused by traditional hard starts, the motor is not driven directly at full duty cycle during startup. Instead, an exponential soft-start PWM ramp-up curve is quantitatively generated based on the motor's electrical time constant, providing a precise duty cycle control reference for subsequent low-impact startup. Generating the exponential soft-start PWM ramp-up curve based on the motor's electrical time constant includes the following steps: Step S201: Using the motor electrical time constant as the time constant factor of the exponentially rising function, the soft-start duration of the exponential soft-start PWM ramp-up curve is determined according to the preset multiple of the time constant factor.

[0046] Step S202: Using the duration of soft start as a time window, establish a time series consisting of multiple discrete time points within the time window, wherein the time interval between adjacent discrete time points in the time series is equal to the PWM control cycle of the MCU.

[0047] Step S203: For each discrete time point in the time series, substitute the time value of the discrete time point into an exponentially increasing function with the motor electrical time constant as the time constant factor to calculate the target duty cycle corresponding to that discrete time point. The function value of the exponentially increasing function starts from zero and increases monotonically with the increase of the time value and gradually approaches the preset maximum duty cycle threshold.

[0048] Step S204: Associate and store each discrete time point in the time series with its corresponding target duty cycle to generate an exponential soft-start PWM ramp-up curve containing the target duty cycle data corresponding to each PWM control cycle within the soft-start duration.

[0049] Specifically, the preset multiplier within the MCU is derived from motor control theory and experimental calibration, typically ranging from 3 to 5 times. Multiplying the obtained motor electrical time constant by the preset multiplier yields the soft-start duration for this startup. This soft-start duration characterizes the time window required from the application of excitation to the motor current reaching a steady-state value. Using this duration as the soft-start duration ensures that the startup process matches the motor's own electrical dynamic characteristics, mitigating the problems of reduced efficiency due to excessively long startup times or insufficient shock suppression due to excessively short startup times.

[0050] Since the MCU's control over the on / off state of MOSFET Q1 in the motor power supply control circuit is based on discrete PWM cycles, the continuous exponential rise curve needs to be discretized. The MCU determines a fixed PWM control period TPWM based on its internal PWM timer configuration; for example, if the PWM frequency is 20kHz, then TPWM = 50μs. Then, using TPWM as the step size, a sequence containing n+1 discrete time points is generated within a time window from 0 to Tsoft, where n = Tsoft / TPWM. This discretization process ensures that the generated rise curve can be precisely executed by the MCU cycle-by-cycle, allowing a unique target duty cycle instruction to be retrieved from the curve for each PWM cycle.

[0051] The exponentially rising function is the target duty cycle = The preset maximum duty cycle threshold is typically set to a fixed value less than or equal to 100% to retain a certain voltage regulation margin and avoid duty cycle saturation. Substituting the identified motor electrical time constant into the exponential function ensures that the duty cycle ramp-up rate precisely matches the electrical time constant of the motor windings. This means the initial duty cycle increment is large to achieve rapid flux establishment, while the increment gradually decreases and smoothly transitions to the maximum duty cycle threshold as the soft-start duration approaches. This matching relationship quantitatively ensures that, within each PWM cycle, the current rise trend generated by the average voltage applied to the motor windings is coordinated with the windings' inductive reactance characteristics, fundamentally mitigating current spikes caused by excessively rapid duty cycle increases or start-up delays caused by excessively slow increases.

[0052] Finally, all the calculated discrete time points and their corresponding target duty cycles are stored in the internal non-volatile memory or random access memory in the form of a data table. The index of this data table is the count value of the PWM cycle, and the table content is the target duty cycle value that should be output in that cycle, thus obtaining a complete and quantified exponential soft-start PWM ramp-up curve for subsequent startup control processes. This curve is not an empirically determined fixed-slope ramp-up, but rather dynamically formulated based on the real-time identified motor electrical time constant. It can precisely match the real-time inductance and resistance of the current motor windings, ensuring that the motor flux build-up follows the optimal electrical transient process during speed increase. This minimizes the starting current surge from the control source, achieving adaptive low-impact startup.

[0053] After generating the exponential soft-start PWM ramp-up curve based on the motor's electrical time constant, the system enters the quantitative low-impact start-up stage. In this stage, the motor is not driven directly with a full duty cycle. Instead, the MOSFET Q1 in the motor power supply control circuit is controlled cycle-by-cycle according to the generated exponential soft-start PWM ramp-up curve, thereby quantitatively applying an increased average voltage to the power supply circuit of the winding motor. Specifically, within each PWM control cycle of the soft-start duration, the target duty cycle corresponding to the current cycle is read from the internally stored exponential soft-start PWM ramp-up curve data table, and this target duty cycle is converted into a PWM drive signal with the corresponding pulse width and output to the control terminal of the motor power supply control circuit. This PWM drive signal controls the switching action of the MOSFET Q1 at a fixed PWM frequency, causing the effective voltage output from the motor power supply to the motor drive commutation circuit via the MOSFET Q1 to gradually increase according to an exponentially rising function, rather than a step-like abrupt change. Meanwhile, during each PWM control cycle of the soft-start process, the MCU repeatedly reads the voltage signal output by the current monitoring circuit through its analog-to-digital converter pin at a sampling rate higher than the PWM frequency. This voltage signal is the amplified value of the voltage difference across the sampling resistor after conditioning by operational amplifier U1. After the MCU performs arithmetic averaging or median filtering on the multiple sampled values, it combines the sampling resistor value with the amplification factor of operational amplifier U1 to calculate the real-time current value of the motor power supply circuit in the current PWM control cycle. After obtaining this real-time current value, the MCU compares it with a preset current threshold to obtain a comparison result. The preset current threshold is set to 110% of the rated current value of the winding motor. This comparison result is used to characterize the deviation of the actual current in the current cycle from the safe upper limit. In this way, during the execution of the exponential soft-start PWM ramp-up curve, the system accurately grasps the dynamic changes of the current through cycle-by-cycle closed-loop monitoring. By implementing cycle-by-cycle conduction control based on the exponential soft-start PWM ramp-up curve, along with real-time current value acquisition and threshold comparison, the motor flux establishment and speed increase process follows the motor's own electrical transient process law. This achieves controlled establishment of the starting current from the control source, effectively mitigating the current spike impact caused by the sudden change in duty cycle during hard start, protecting the motor windings, fuses, and semiconductor devices in the power supply circuit, and improving electrical safety and operational stability during the start-up phase.

[0054] In the process of gradually increasing the effective voltage of the motor power supply by turning on the MOSFET Q1 cycle by cycle through the exponential soft-start PWM ramp-up curve, a dynamic correction mechanism based on real-time current closed-loop is introduced throughout the soft-start process to mitigate the deviation of the actual current from the expected curve caused by factors such as differences in individual motor parameters, load fluctuations, or power supply voltage disturbances. Specifically, within each PWM control cycle included in the soft-start duration, the system does not mechanically execute the preset target duty cycle in the curve, but dynamically adjusts the duty cycle of the current cycle cycle by cycle based on the real-time feedback current deviation, thereby strictly keeping the actual current within a safe limit. The dynamic adjustment of the PWM duty cycle based on the comparison results to ensure that the real-time current value does not exceed the preset current threshold includes the following steps: Step S205: Obtain the first real-time current value output by the current monitoring circuit in each PWM control cycle of the exponential soft-start PWM ramp-up curve, and obtain the first current deviation value of the current cycle by subtracting the first real-time current value from the preset current threshold.

[0055] Step S206: The first current deviation value of the current cycle is used as the input of the PID closed-loop controller. After the PID closed-loop controller performs proportional, integral and derivative operations, it outputs the first duty cycle adjustment increment of the current cycle.

[0056] Step S207: The first duty cycle adjustment increment of the current cycle is superimposed with the first target duty cycle corresponding to the current PWM control cycle in the exponential soft-start PWM ramp-up curve to obtain the first dynamic correction duty cycle of the current cycle.

[0057] Step S208: The first dynamic correction duty cycle of the current cycle is used as the first actual control signal of the motor power supply control circuit in the current PWM control cycle to drive the motor power supply control circuit to conduct according to the first dynamic correction duty cycle, so as to adjust the first effective voltage output by the motor power supply to the motor drive commutation circuit.

[0058] Step S209: In the next PWM control cycle, the second real-time current value output by the current monitoring circuit is reacquired and the second current deviation value is recalculated to update the duty cycle adjustment increment. Based on the updated duty cycle adjustment increment, the target duty cycle corresponding to the next PWM control cycle in the exponential soft-start PWM climbing curve is corrected. This process is repeated until the real-time current value is not greater than the preset current threshold or the exponential soft-start PWM climbing curve is completed.

[0059] Specifically, within each PWM control cycle, the MCU repeatedly reads the voltage signal output by operational amplifier U1 in the current monitoring circuit through its analog-to-digital converter pin at a sampling rate higher than the PWM frequency. This voltage signal is the amplified value of the voltage across the sampling resistor. The MCU performs an arithmetic average filter on the multiple voltage samples collected in the current cycle to suppress transient noise interference. Then, it combines the resistance value of the sampling resistor and the amplification factor of operational amplifier U1 to calculate the real-time current value of the motor power supply circuit in the current PWM control cycle, and records this real-time current value as the first real-time current value. The MCU reads a preset current threshold from its internal register, preferably 110% of the rated current value of the winding motor, and calculates the difference between the first real-time current value and the preset current threshold to obtain the first current deviation value for the current cycle. When the first real-time current value is less than the preset current threshold, the first current deviation value is negative, indicating that the current current is still within the safe range, and the system can continue to increase the duty cycle according to the original curve; when the first real-time current value is greater than the preset current threshold, the first current deviation value is positive, indicating that the current current has exceeded the safe limit, and the duty cycle needs to be adjusted downward immediately.

[0060] The MCU integrates a digital PID closed-loop controller, whose input is the first current deviation value. The PID closed-loop controller performs proportional, integral, and derivative operations on the input first current deviation value. The proportional operation provides an immediate response to the current deviation, the integral operation eliminates historical accumulated deviations to improve steady-state accuracy, and the derivative operation predicts the deviation change trend to enhance system stability. The results of the proportional, integral, and derivative operations are weighted and summed according to preset weighting coefficients to obtain the first duty cycle adjustment increment for the current cycle. This first duty cycle adjustment increment is a signed value; its positive or negative sign indicates the direction of duty cycle adjustment, and its absolute value indicates the adjustment magnitude. The proportional coefficient, integral time constant, and derivative time constant of the PID controller are preferably predetermined using engineering tuning methods and stored in the MCU's non-volatile memory to ensure stable closed-loop regulation performance under different operating conditions. By introducing a PID closed-loop controller, the precise duty cycle correction can be quantitatively calculated based on the current deviation value, enabling the current regulation process to achieve both rapid response and stable control.

[0061] The MCU reads the original target duty cycle corresponding to the current PWM control cycle from the internally stored exponential soft-start PWM ramp-up curve data table, and records this original target duty cycle as the first target duty cycle. Then, the first duty cycle adjustment increment is algebraically superimposed with the first target duty cycle to obtain the first dynamic correction duty cycle for the current cycle. When the first current deviation is positive, the first duty cycle adjustment increment is negative, and the superimposed first dynamic correction duty cycle is less than the original first target duty cycle, thus reducing the actual effective output voltage for this cycle and achieving current reduction. When the first current deviation is negative, the first duty cycle adjustment increment is positive, and the superimposed first dynamic correction duty cycle is greater than the original first target duty cycle, moderately increasing the actual effective output voltage and accelerating the response speed of the current approaching the preset threshold. This superposition correction operation is executed independently in each PWM control cycle, ensuring that the duty cycle correction is based on dynamic adjustment of the real-time current feedback of the current cycle, rather than simply relying on the correction result of the previous cycle, thereby guaranteeing the timeliness and accuracy of closed-loop regulation.

[0062] The MCU writes the first dynamically corrected duty cycle into the comparison matching register of its PWM waveform generator. Based on the value of this register, the PWM waveform generator outputs a PWM drive signal with the corresponding pulse width within the current PWM control cycle. This PWM drive signal is applied to the gate of MOSFET Q2 after being current-limited by resistor R4 in the motor power supply control circuit. Within each PWM cycle, when the PWM drive signal is high, MOSFET Q2 is turned on, pulling the gate potential of MOSFET Q1 low, causing MOSFET Q1 to saturate and conduct. The positive voltage of the motor power supply is output to the motor drive commutation circuit through MOSFET Q1, supplying power to the film-winding motor. When the PWM drive signal is low, MOSFET Q2 is turned off, and MOSFET Q1 is also turned off, cutting off the motor power supply output. Therefore, the first dynamically corrected duty cycle determines the ratio of the conduction time of MOSFET Q1 within the current PWM cycle to the entire PWM cycle. This ratio directly determines the average voltage value output by the motor power supply to the motor drive commutation circuit, i.e., the first effective voltage. By using the first dynamically corrected duty cycle as the actual control signal for the current cycle, the average voltage applied to the winding motor is no longer the fixed value preset by the curve, but an optimized value after dynamic correction by current closed-loop feedback. This ensures that even if there are power supply voltage fluctuations or motor parameter deviations during the soft start process, the actual current can still be accurately controlled within a safe range.

[0063] After the current PWM control cycle ends, the PWM timer generates a cycle overflow interrupt, triggering the start of the next PWM control cycle. In the next PWM control cycle, the MCU again follows step S205, acquiring the real-time current value output by the current monitoring circuit through the analog-to-digital converter pin. This real-time current value is recorded as the second real-time current value, and the difference between this value and a preset current threshold is used to obtain the second current deviation value. Steps S206 to S208 are then repeated: the second current deviation value is input into the PID closed-loop controller to obtain the updated duty cycle adjustment increment. This updated duty cycle adjustment increment is then superimposed with the target duty cycle corresponding to the next PWM control cycle in the exponential soft-start PWM ramp-up curve to obtain the second dynamically corrected duty cycle for the current cycle. This second dynamically corrected duty cycle is used as the actual control signal for the next PWM control cycle to drive the motor power supply control circuit. This process is repeated in each PWM control cycle, forming a cycle-by-cycle closed-loop iterative adjustment mechanism. This cycle continues until either of the following exit conditions is met: First, the real-time current value of the current cycle, after closed-loop adjustment, no longer exceeds the preset current threshold, indicating that the current has been successfully clamped within the safety limit, and the system resumes subsequent control according to the exponential soft-start PWM ramp-up curve; Second, all discrete time points of the exponential soft-start PWM ramp-up curve have been executed, the soft-start phase ends normally, and the system smoothly transitions to the constant power operation phase. Through this cycle-by-cycle closed-loop iterative adjustment mechanism, precise monitoring and dynamic adjustment of the current can be maintained throughout the entire soft-start process, ensuring that the current during the start-up phase never exceeds the safety boundary. By superimposing real-time dynamic adjustment capability on the feedforward control benchmark of the exponential soft-start PWM ramp-up curve, the system can adaptively correct the duty cycle according to factors such as individual motor differences, load fluctuations, and power supply voltage disturbances, precisely clamping the peak starting current below the preset current threshold. This fundamentally alleviates the risk of current surges caused by parameter matching deviations in hard starts or simple open-loop soft starts, significantly improving the electrical safety and load adaptability of the start-up process.

[0064] In step S300, during the stop phase, the differential value of the real-time current value with respect to time is continuously calculated. When the differential value reaches the preset negative slope threshold, the PWM duty cycle is controlled to decrease to zero in an exponential manner, and the motor drive commutation circuit is controlled to short-circuit phases A and B of the film winding motor.

[0065] Based on the current closed-loop control during the startup and operation phases, the system synchronously activates stop prediction monitoring based on current differential after the film winding motor enters stable operation, replacing the traditional stop method that relies on passive triggering by limit switches. Specifically, within each PWM control cycle of the film winding motor's continuous operation, the MCU repeatedly acquires the voltage signal output by the current monitoring circuit through its analog-to-digital conversion pin at a sampling rate higher than the PWM frequency. This voltage signal is the amplified value of the voltage difference across the sampling resistor after conditioning by operational amplifier U1. After the MCU performs arithmetic average filtering on the multiple voltage sample values ​​acquired in each PWM control cycle, it combines the resistance value of the sampling resistor with the amplification factor of operational amplifier U1 to calculate the real-time current value I(t) of the motor power supply circuit in the current PWM control cycle. Based on this, the MCU calculates the differential value dI / dt of the real-time current value I(t) with respect to time t in a fixed time window, that is, within each PWM control cycle, the difference between the real-time current value of the current cycle and the real-time current value of the previous cycle is divided by the interval between two adjacent cycles to obtain the real-time current change rate of the current cycle. The MCU internal register has a preset negative slope threshold γ. This preset negative slope threshold γ is determined by multiplying the ratio of the rated current value of the film winding motor to the current sampling period of the MCU by a preset coefficient. The specific expression is: preset negative slope threshold = -0.8 * (rated current value / current sampling period). The preset coefficient -0.8 is obtained through multiple calibration tests on the current drop slope of the same model of film winding motor when it approaches the limit switch, so as to quantitatively characterize the critical rate of change of the current of the film winding motor that drops sharply when it is about to touch the limit switch.

[0066] When the real-time differential value is less than or equal to the preset negative slope threshold, that is, when the rate of decrease of the real-time current value reaches or exceeds the calibrated critical rate of change, it indicates that the film winding motor has moved close to the limit switch position. The load increases sharply, causing the current to drop rapidly. At this time, the MCU determines that the film winding motor is about to reach its destination and immediately generates a pre-destination flag signal. Through the above-mentioned stop prediction mechanism based on cycle-by-cycle real-time differential calculation and comparison with the negative slope threshold, the system can accurately identify the arrival trend before the mechanical limit switch actually moves. This allows sufficient control response time for the subsequent deceleration and stopping procedure, fundamentally alleviating the rigid collision between the high-speed film winding motor and the limit switch, improving the electrical life of the limit switch, and eliminating the positioning deviation caused by mechanical rebound after the collision, thus improving the accuracy of the film winding stop position.

[0067] Subsequently, the PWM duty cycle is controlled to decrease exponentially to zero. This process involves: determining an initial decreasing duty cycle based on the difference between a preset negative slope threshold and the derivative value; using the motor's electrical time constant as the time constant factor of the exponential decay function; and controlling the PWM duty cycle to decrease periodically to zero from the initial decreasing duty cycle according to the exponential decay function.

[0068] Specifically, the initial decreasing duty cycle is determined based on the difference between the preset negative slope threshold and the differential value, i.e., initial decreasing duty cycle = preset proportional coefficient * (negative slope threshold - differential value). A larger difference in the preset proportional coefficient indicates a more rapid trend towards reaching the desired position, and a higher initial decreasing duty cycle value is used to quickly reduce the driving force. The motor's electrical time constant is used as the time constant factor for the exponential decay function. Following this exponential decay function, the PWM duty cycle is controlled to decrease periodically from the initial decreasing duty cycle to zero, ensuring that the average voltage applied to the motor windings decreases smoothly at a rate matching the motor's own electrical dynamic characteristics, mitigating current surges and mechanical oscillations caused by sudden duty cycle drops. Simultaneously, the MCU outputs a short-circuit control signal to the relay in the motor drive commutation circuit through its second control signal output terminal. This controls the relay to short-circuit the A-phase and B-phase power input terminals of the winding motor. During inertial rotation, the winding motor generates a back EMF damping braking torque due to the closed loop formed by the A-phase and B-phase windings, achieving coordinated electrical braking and mechanical limit stop. By combining the above-mentioned exponentially decreasing soft stop triggered by the negative slope threshold of the current derivative with the short-circuit damping braking of the winding, the system completes the main deceleration process before the mechanical limit switch is activated. The limit switch only touches the stop at a very low speed, which fundamentally solves the mechanical wear and positioning deviation problems caused by the full-speed impact of the limit switch in the traditional hard stop method, extends the service life of the limit switch, and improves the repeatability of the film winding stop position.

[0069] This application also provides a computer storage medium storing a computer program that, when run on a computer, enables the computer to execute the steps in the control method for a film winding motor described above.

[0070] It should be understood that although the steps in the flowcharts in the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order requirement for the execution of these steps, and they can be performed in other orders.

[0071] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A control method for a film winding motor, characterized in that, The method includes: The excitation voltage and peak excitation current of the motor power supply are obtained under the excitation of the probe pulse output by the MCU. The motor electrical time constant is determined based on the excitation voltage and peak excitation current. The target power limit for this operation is determined based on the motor electrical time constant. During the startup phase, an exponential soft-start PWM ramp-up curve is generated based on the motor electrical time constant. The motor power supply control circuit is turned on according to the exponential soft-start PWM ramp-up curve. The real-time current value output by the current monitoring circuit is collected in real time. The real-time current value is compared with a preset current threshold to obtain a comparison result. The PWM duty cycle is dynamically adjusted according to the comparison result to ensure that the real-time current value does not exceed the preset current threshold. During the stopping phase, the derivative of the real-time current value with respect to time is continuously calculated. When the derivative value reaches the preset negative slope threshold, the PWM duty cycle is controlled to decrease to zero in an exponential manner, and the motor drive commutation circuit is controlled to short-circuit phases A and B of the film winding motor.

2. The method according to claim 1, characterized in that, The step of determining the motor electrical time constant based on the excitation voltage value and the peak excitation current includes: The ratio of the excitation voltage value to the peak value of the excitation current is used as the DC resistance value of the motor winding; The product of the rate of change of current during the duration of the probe pulse excitation and the DC resistance of the motor winding is used as the inductance estimate. The ratio of the estimated inductance value to the DC resistance value of the motor winding is used as the electrical time constant of the motor.

3. The method according to claim 2, characterized in that, The step of generating the exponential soft-start PWM ramp-up curve based on the motor electrical time constant includes: The time constant factor of the exponentially rising function is used as the electrical time constant of the motor, and the soft start duration of the exponential soft start PWM ramp-up curve is determined according to a preset multiple of the time constant factor. Using the duration of the soft start as a time window, a time series consisting of multiple discrete time points is established within the time window, wherein the time interval between adjacent discrete time points of the time series is equal to the PWM control cycle of the MCU. For each discrete time point in the time series, the time value of the discrete time point is substituted into an exponentially increasing function with the motor electrical time constant as the time constant factor to calculate the target duty cycle corresponding to that discrete time point. The function value of the exponentially increasing function starts from zero and increases monotonically with the increase of the time value and gradually approaches the preset maximum duty cycle threshold. The discrete time points in the time series are associated with their respective target duty cycles and stored to generate an exponential soft-start PWM ramp-up curve containing the target duty cycle data for each PWM control cycle within the soft-start duration.

4. The method according to claim 3, characterized in that, The step of dynamically adjusting the PWM duty cycle based on the comparison result to ensure that the real-time current value does not exceed the preset current threshold includes: The first real-time current value output by the current monitoring circuit in each PWM control cycle of the exponential soft-start PWM ramp-up curve is obtained, and the first real-time current value is subtracted from the preset current threshold to obtain the first current deviation value of the current cycle. The first current deviation value of the current cycle is used as the input of the PID closed-loop controller. After the PID closed-loop controller performs proportional, integral and derivative operations, it outputs the first duty cycle adjustment increment of the current cycle. The first duty cycle adjustment increment of the current cycle is superimposed with the first target duty cycle corresponding to the current PWM control cycle in the exponential soft-start PWM ramp-up curve to obtain the first dynamic correction duty cycle of the current cycle; The first dynamic correction duty cycle of the current cycle is used as the first actual control signal of the motor power supply control circuit in the current PWM control cycle to drive the motor power supply control circuit to conduct according to the first dynamic correction duty cycle, so as to adjust the first effective voltage output by the motor power supply to the motor drive commutation circuit. In the next PWM control cycle, the second real-time current value output by the current monitoring circuit is reacquired and the second current deviation value is recalculated to update the duty cycle adjustment increment. Based on the updated duty cycle adjustment increment, the target duty cycle corresponding to the next PWM control cycle in the exponential soft-start PWM ramp-up curve is corrected. This process is repeated until the real-time current value is not greater than the preset current threshold or the exponential soft-start PWM ramp-up curve is completed.

5. The method according to claim 1, characterized in that, The control of the PWM duty cycle to decrease to zero in an exponentially decreasing manner includes: The initial decreasing duty cycle is determined based on the difference between the preset negative slope threshold and the differential value. The motor electrical time constant is used as the time constant factor of the exponential decay function, and the PWM duty cycle is controlled to decrease to zero cycle by cycle from the initial decreasing duty cycle according to the exponential decay function.

6. A control system for a film winding motor, characterized in that, The system executes a control method for a film winding motor as described in any one of claims 1 to 5, and the system includes: The motor power supply and system power supply are isolated from each other, wherein the motor power supply is used to provide drive power for the film winding motor, and the system power supply is used to provide power to other component modules in the control system independently of the motor power supply; The voltage monitoring circuit has its input terminal connected across the back end of the fuse in the output circuit of the motor power supply and ground, and its output terminal connected to the MCU. It is used to collect the voltage signal at the back end of the fuse under the detection pulse output by the MCU, and transmit the voltage signal to the MCU so that the MCU can determine the excitation voltage value based on the voltage signal. The current monitoring circuit has its input terminal connected across the sampling resistor in the output circuit of the motor power supply, and its output terminal connected to the MCU. It is used to acquire the voltage difference signal across the sampling resistor under the excitation of the detection pulse output by the MCU, and transmit the voltage difference signal to the MCU so that the MCU can determine the peak value of the excitation current based on the voltage difference signal, and calculate the motor electrical time constant based on the excitation voltage value and the excitation current value. A motor power supply control circuit is connected in series between the rear end of the fuse and the motor drive commutation circuit. Its control terminal is connected to the MCU and is used to turn on or off according to the PWM drive signal output by the MCU during the startup phase. The duty cycle of the PWM drive signal changes periodically according to the exponential soft-start PWM ramp-up curve generated based on the motor electrical time constant. The MCU corrects the duty cycle of the current cycle according to the comparison result between the real-time current value fed back by the current monitoring circuit and the preset current threshold, so that the real-time current value does not exceed the preset current threshold. A motor drive steering circuit is connected between the output terminal of the motor power supply control circuit and the film winding motor, and includes a relay for switching the power supply polarity of phase A and phase B of the film winding motor according to the control signal of the MCU. The MCU is also used to calculate the derivative of the real-time current value with respect to time based on the real-time current value fed back by the current monitoring circuit during the stop phase. When the derivative value reaches the preset negative slope threshold, the PWM duty cycle is controlled to decrease to zero in an exponential manner, and the motor drive commutation circuit is controlled to short-circuit the A and B phases of the film winding motor.

7. The system according to claim 6, characterized in that, The system also includes: The communication module connected to the MCU is used to receive external control commands and send the status information of the MCU.

8. The system according to claim 6, characterized in that, The system also includes: A surge protection circuit is connected between the output terminal of the current monitoring circuit and the film winding motor to suppress surges in the film winding motor. An isolation relay is connected in series between the output terminal of the surge protection circuit and the film winding motor, and its control terminal is connected to the MCU to turn on or off the current loop of the film winding motor according to the control signal of the MCU. An isolation voltage reversal detection circuit is provided, with its input terminals connected to the output terminal of the motor drive steering circuit and the input terminal of the film winding motor, respectively, and its output terminal connected to the MCU. The circuit is used to transmit the comparison result between the output polarity of the motor drive steering circuit and the input polarity of the film winding motor to the MCU.

9. The system according to claim 6, characterized in that, The motor-driven steering circuit includes: A relay, wherein the relay includes a first coil, a first normally open contact, a first normally closed contact, a first common terminal, a second normally open contact, a second normally closed contact, and a second common terminal; The first end of the first coil is connected to the first control signal output terminal of the MCU, and the second end of the first coil is grounded. The first common terminal is connected to the output terminal of the motor power supply control circuit, the first normally open contact is connected to the A-phase power supply input terminal of the film winding motor, and the first normally closed contact is connected to the B-phase power supply input terminal of the film winding motor. The second common terminal is connected to the output terminal of the motor power supply control circuit, the second normally open contact is connected to the B-phase power supply input terminal of the film winding motor, and the second normally closed contact is connected to the A-phase power supply input terminal of the film winding motor. The MCU controls the relay to engage via a positive control signal output from the first control signal output terminal, so that the output terminal of the motor power supply control circuit simultaneously forms a first polarity connection with both the A-phase power supply input terminal and the B-phase power supply input terminal. The MCU controls the relay to reset through the reverse control signal output from the first control signal output terminal, so that the output terminal of the motor power supply control circuit simultaneously forms a second polarity connection with the A-phase power supply input terminal and the B-phase power supply input terminal.

10. A computer-readable storage medium having a computer program stored thereon that can run on a processor, characterized in that, When the computer program is executed by the processor, it implements a control method for a film winding motor as described in any one of claims 1 to 5.

Images