Grass mowing motor starting jitter optimization method, system and equipment and storage medium

Abstract

The invention relates to the field of motor control, and discloses a grass mowing motor starting jitter optimization method, system and device and a storage medium. The method comprises the steps that after an MCU is powered on, the MCU outputs a reverse PWM signal to a motor modulator until a rotor is pushed to a preset initial position; the MCU outputs a low-duty-ratio PWM signal to the motor modulator to control the rotor to start rotating from a preset initial position until the counter electromotive force reaches a preset rotating speed threshold value, the duty ratio of the low-duty-ratio PWM signal is smaller than or equal to 20%, and the preset rotating speed threshold value corresponds to the lowest rotating speed when the brushless motor can recognize the zero crossing point of the counter electromotive force; and the MCU outputs an adjusting duty ratio PWM signal to the motor modulator according to the difference value between the real-time rotating speed of the rotor and the target rotating speed so as to dynamically adjust the real-time rotating speed of the rotor. The rotating speed stability in the operation stage is guaranteed, and the practical application value is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of motor control, and particularly relates to a grass-beating motor start-up jitter optimization method, system, device and storage medium. BACKGROUND

[0002] In the prior art, a grass-beating motor adopts a sensorless design, and its rotation speed detection is realized by detecting the zero-crossing time of back electromotive force.

[0003] However, this mechanism has obvious limitations: when the grass-beating motor is in a stationary state or a very low speed running state, the back electromotive force generated by the motor is almost negligible, which causes the MCU (Microcontroller Unit) to be unable to effectively detect the motor rotation speed. If a closed-loop rotation speed control mode is directly used in this case, the MCU will first set a target rotation speed, which will cause the initial PWM (Pulse-Width Modulation) duty cycle to be too large; the large PWM duty cycle will cause the stator magnetic field switching frequency to be too fast, and at this time the motor rotor has not yet established a stable physical position, ultimately causing the grass-beating motor to appear jitter, reverse rotation, or even start-up failure. SUMMARY

[0004] Therefore, the present application aims to overcome the deficiencies in the prior art and provide a grass-beating motor start-up jitter optimization method, system, device and storage medium.

[0005] The present application provides the following technical solutions: In a first aspect, the present application provides a grass-beating motor start-up jitter optimization method, which is applied to a grass-beating motor start-up jitter optimization system, the grass-beating motor start-up jitter optimization system comprising an MCU, a motor modulator and a brushless motor, the brushless motor comprising a rotor, and the method comprising: After the MCU is powered on, the MCU outputs a reverse PWM signal to the motor modulator until the rotor is pushed to a preset initial position; The MCU outputs a low-duty-cycle PWM signal to the motor modulator to control the rotor to start rotating from the preset initial position until the back electromotive force reaches a preset rotation speed threshold, the duty cycle of the low-duty-cycle PWM signal being ≤20%, and the preset rotation speed threshold corresponding to the lowest rotation speed at which the brushless motor can identify the zero-crossing time of the back electromotive force; The MCU outputs an adjusted-duty-cycle PWM signal to the motor modulator to dynamically adjust the real-time rotation speed of the rotor according to the difference between the real-time rotation speed of the rotor and a target rotation speed.

[0006] In an optional implementation, the step of the MCU outputting a reverse PWM signal to the motor modulator until the rotor is pushed to a preset initial position includes: After the MCU is powered on, it outputs the reverse PWM signal to the motor modulator and monitors the phase current change rate. When the phase current change rate is detected to be less than a preset change rate threshold, it is determined that the rotor has reached the preset initial position, and the output of the reverse PWM signal to the motor modulator is stopped.

[0007] In an optional implementation, the step of the MCU outputting a low duty cycle PWM signal to the motor modulator to control the rotor to rotate from the preset initial position until the back electromotive force reaches a preset speed threshold includes: The MCU outputs the low duty cycle PWM signal to the motor modulator, and the motor modulator drives the stator windings of the brushless motor to commutate in a predetermined order according to the low duty cycle PWM signal, so that the rotor gradually accelerates its rotation from the preset initial position. The MCU monitors the back electromotive force in real time. When the peak value of the back electromotive force reaches 10% to 15% of the bus voltage, or the effective amplitude of a single end exceeds 0.2 to 0.3V, it is determined that the back electromotive force has reached the preset speed threshold.

[0008] In an optional implementation, the step of the MCU outputting a low duty cycle PWM signal to the motor modulator to control the rotor to rotate from the preset initial position until the back electromotive force reaches a preset speed threshold further includes: The MCU outputs the low duty cycle PWM signal to the motor modulator to control the rotor to start rotating from the preset initial position; The MCU increases the low duty cycle PWM signal according to a linear or exponential curve, and monitors the back electromotive force of the brushless motor in real time; When the preset conditions are met, it is determined that the back electromotive force reaches the preset speed threshold. The preset conditions include: in multiple consecutive commutation cycles, the period error of the back electromotive force waveform is less than the preset error threshold, which is 3% to 8%.

[0009] In an optional implementation, the preset condition further includes: the back electromotive force is greater than or equal to a preset dynamic threshold.

[0010] in, The preset dynamic threshold, This indicates the proportion of the back electromotive force to the bus voltage under the current bus voltage; This refers to the bus voltage measured in real time. This is a temperature compensation function used to correct the effect of magnetic flux decay on the amplitude of the back electromotive force.

[0011] In an optional implementation, while real-time monitoring of the back electromotive force of the three phases of the brushless motor, the method further includes: The MCU uses a moving average filter or a band-stop filter to remove PWM noise.

[0012] In an optional implementation, the method further includes: If, starting from the time when the low duty cycle PWM signal is output from the MCU to the motor modulator, the back electromotive force still has not reached the preset speed threshold after the Nth time exceeding the preset time, the commutation sequence is automatically switched once, and the reverse PWM signal is output from the MCU to the motor modulator until the rotor is pushed to the preset initial position, where N≤2; If the timing starts from the output of the low duty cycle PWM signal from the MCU to the motor modulator and two consecutive startup failures occur, the low duty cycle PWM signal is reduced, and the MCU returns to outputting the reverse PWM signal to the motor modulator until the rotor is pushed to the preset initial position.

[0013] Secondly, the present invention provides a grass-trimming motor start-up vibration optimization system, including an MCU, a motor modulator and a brushless motor, wherein the brushless motor includes a rotor; The MCU is used to output a reverse PWM signal, a low duty cycle PWM signal, and an adjustable duty cycle PWM signal to the motor modulator after power-on. The motor modulator is used to push the rotor to a preset initial position according to the reverse PWM signal, control the rotor to start rotating from the preset initial position according to the low duty cycle PWM signal, and dynamically adjust the real-time speed of the rotor according to the adjusted duty cycle PWM signal.

[0014] Thirdly, this disclosure provides a computer device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the grass-beating motor start-up vibration optimization method described in the first aspect.

[0015] Fourthly, this disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the grass-trimming motor start-up vibration optimization method described in the first aspect.

[0016] The beneficial effects of this application are: The grass trimmer motor start-up vibration optimization method provided in this application addresses the problems of "start-up vibration, reverse rotation, and start-up failure" in existing sensorless BLDC grass trimmer motors. Through a four-stage logic of "initial positioning → throttle start → delay waiting → closed-loop control", it avoids the problems of start-up vibration, reverse rotation, and start-up failure, while ensuring the speed stability during operation. Moreover, it does not require additional sensors, thus balancing control reliability and cost advantages.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the various drawings, similar components are numbered similarly.

[0019] Figure 1 The flowchart of a grass-trimming motor start-up vibration optimization method provided in an embodiment of this application is shown; Figure 2 This paper shows a schematic diagram of a grass-trimming motor start-up vibration optimization system provided in an embodiment of this application; Figure 3 A schematic diagram of the structure of a computer device provided in an embodiment of this application is shown. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the template description is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] Example 1 like Figure 1 The diagram shown is a flowchart of a grass-trimming motor start-up vibration optimization method according to an embodiment of this application. The grass-trimming motor start-up vibration optimization method provided in this embodiment of the application is applied to a grass-trimming motor start-up vibration optimization system, which includes an MCU, a motor modulator, and a brushless motor. The optimization method for grass mower motor start-up vibration includes the following steps: In step S110, after powering on the MCU, the MCU outputs a reverse PWM signal to the motor modulator until the rotor is pushed to the preset initial position.

[0024] Understandably, after the MCU powers on, it completes the initialization of the peripheral circuits to ensure the normal operation of subsequent signal outputs and control logic. At this time, the brushless motor is stationary, and the position of the rotor's magnetic poles is unknown. In this embodiment, the peripheral circuits include PWM modules, timers, and other circuits related to motor control.

[0025] Next, the MCU outputs a reverse PWM signal to the motor modulator. The duty cycle of the reverse PWM signal can be 10% to 20% (the specific value depends on the motor power: 10% to 15% for low-power motors (≤300W) and 15% to 20% for high-power motors (300W to 1000W)). Since the brushless motor contains stator windings, after receiving the reverse PWM signal, the motor modulator will turn on the corresponding MOSFET or IGBT power device, causing current to flow through the stator windings and forming a directional magnetic field around them. The rotor has its own permanent magnets. When the direction of this directional magnetic field is opposite to the direction of the rotor's currently unknown magnetic poles, an electromagnetic repulsion force will be generated between them. This repulsion force will push the rotor to a predictable preset initial position. This preset initial position can match the initial requirements of the brushless motor's subsequent drive according to a predetermined commutation sequence (such as 120° electrical angle commutation), laying the foundation for stable rotor startup.

[0026] After the MCU outputs the reverse PWM signal to the motor modulator, it monitors the phase current through the sampling resistor connected in series in the stator winding. The MCU converts the analog current signal into a digital signal and calculates the current difference between two adjacent sampling periods (such as a 1ms interval), i.e., the phase current change rate.

[0027] Understandably, when the rotor has not reached the preset initial position, the magnetic reluctance between its permanent magnet and the stator's directional magnetic field is relatively high, resulting in a high rate of change of phase current. When the rotor moves to the preset initial position, the magnetic reluctance reaches its minimum value, the phase current tends to stabilize, and the rate of change decreases significantly. Therefore, when the detected rate of change of phase current is less than the preset rate of change threshold (usually set to 0.5A / ms~1A / ms, adjusted according to the motor's magnetic reluctance characteristics), it is determined that the rotor has reached the preset initial position. Once the positioning determination condition is met, the MCU immediately stops outputting the reverse PWM signal to prevent the rotor from continuing to move due to inertia. Optionally, if the phase current rate of change is not detected to meet the standard within the timeout protection time (500ms), positioning is determined to have failed, triggering an alarm (such as LED flashing) and indicating a circuit fault (such as an open sampling resistor or a damaged power device).

[0028] The above steps, through reverse PWM signal output and phase current change rate monitoring, achieve rotor preset initial position positioning. First, it solves the core problem of unknown rotor magnetic pole position before brushless motor start-up. The electromagnetic repulsion force generated by the directional magnetic field can accurately push the rotor to the initial position matching the subsequent commutation sequence, fundamentally avoiding start-up reversal caused by commutation disorder. Second, real-time monitoring of phase current change rate ensures positioning accuracy and avoids rotor overshoot or positioning deviation. At the same time, the timeout protection and alarm mechanism can promptly identify faults such as open circuit of sampling resistor and damage to power devices, improving system reliability. Moreover, the entire positioning process does not require additional Hall sensors or other hardware, relying only on the existing MCU and sampling circuit, reducing hardware costs and installation complexity while ensuring positioning effect.

[0029] In step S120, the MCU outputs a low duty cycle PWM signal to the motor modulator to control the rotor to start rotating from the preset initial position until the back EMF reaches a preset speed threshold. The duty cycle of the low duty cycle PWM signal is ≤20%, and the preset speed threshold corresponds to the lowest speed at which the brushless motor can identify the zero point of the back EMF.

[0030] Specifically, after entering the startup phase, the MCU switches to throttle control mode (i.e., open-loop control mode), no longer relying on speed feedback for adjustment, but instead outputs a fixed low duty cycle PWM signal (≤20%) to the motor modulator.

[0031] After receiving a low duty cycle PWM signal, the motor modulator drives the stator windings of the brushless motor to commutate sequentially according to a preset commutation sequence (e.g., a 120° electrical angle commutation sequence adapted to the brushless motor). Because the PWM signal has a low duty cycle, the magnetic field strength formed by the stator windings is weak (i.e., a weak magnetic field). This weak magnetic field generates a stable driving force on the rotor, causing it to gradually accelerate from the preset initial position determined in step S110, avoiding vibration or reverse rotation during startup due to an excessively strong magnetic field. Simultaneously, the rotor gradually establishes its initial speed during rotation. As the speed increases, the stator windings of the brushless motor induce a back electromotive force (EMF) signal. When the back EMF meets any of the following conditions, a preset speed threshold is reached (i.e., the motor speed is high enough that the zero-crossing point of the back EMF can be accurately detected): (1) Amplitude threshold determination (applicable to voltage stability scenarios) If the peak value of the back electromotive force (EMF) reaches 10%~15% of the bus voltage (e.g., peak value ≥1.2V~1.8V when the bus voltage is 12V), or the single-ended effective amplitude (effective value) of the back EMF exceeds 0.2V~0.3V, then the back EMF is determined to have reached the preset speed threshold. Parameter basis: 10%~15% of the bus voltage is the minimum effective amplitude for zero-crossing detection of the back EMF. Below 10%, the signal amplitude is close to noise level, and the detection error is >10%; above 15%, although the detection accuracy is higher, it will prolong the startup time and affect the user experience. (2) Periodic error + dynamic threshold determination (applicable to temperature / voltage fluctuation scenarios) When the ambient temperature changes (e.g., high temperature in summer, low temperature in winter) or the bus voltage fluctuates (e.g., voltage drop when powered by battery), the back EMF amplitude will be affected by magnetic flux attenuation (temperature rise leads to a decrease in permanent magnet magnetic flux) and voltage drop. At this time, it is necessary to combine the period error and dynamic threshold for judgment: (a) Period error judgment: continuously collect the back EMF waveform for 3 to 5 commutation cycles, calculate the time difference of each cycle, and the error must be less than the preset error threshold. The preset error threshold is 3% to 8%. The design basis of this threshold is the indicator of stable speed. When the error is >8%, the speed fluctuation is too large, and the closed-loop control is prone to overshoot; when the error is <3%, the speed is too stable, but it will prolong the start-up time; (b) Dynamic threshold judgment: the back EMF must be greater than or equal to the preset dynamic threshold, and its calculation formula is:

[0032] in, The preset dynamic threshold, This indicates the proportion of the back electromotive force to the bus voltage under the current bus voltage; This refers to the bus voltage measured in real time. The temperature compensation function is used to correct the effect of magnetic flux attenuation on the back electromotive force amplitude. It should be noted that while monitoring the back electromotive force of the three phases of the brushless motor in real time, the high-frequency switching of the PWM signal will cause noise to be mixed into the back electromotive force sampling signal (the frequency is consistent with the PWM carrier frequency of 20kHz~50kHz). If it is not processed, it will lead to false triggering of the threshold judgment. Therefore, the MCU needs to adopt the following filtering methods: (1) Moving average filtering: take the back electromotive force value of 5~10 consecutive sampling periods to calculate the average, smooth the high-frequency noise. The advantage is that the amount of calculation is small and the real-time performance is high (the number of sampling periods of moving average filtering can be adjusted according to the noise intensity. When the noise is large, take 10 periods and when the noise is small, take 5 periods); (2) Band-stop filter: design a band-stop filter with a center frequency of 20kHz~50kHz for the PWM carrier frequency to directly filter out noise of specific frequencies. It is suitable for scenarios with severe noise interference (such as outdoor dust and high humidity environments).

[0033] The above steps are based on low duty cycle PWM (≤20%) open-loop control. The rotor is driven by a weak magnetic field to start smoothly from the preset initial position, completely avoiding the start-up jitter caused by the rotor's inability to follow the magnetic field switching too quickly during traditional high duty cycle start-ups. Secondly, the dual mechanism of back EMF amplitude threshold determination and period error + dynamic threshold determination not only adapts to rapid detection in stable voltage scenarios, but also addresses the magnetic flux attenuation problem caused by high temperature, low temperature or voltage fluctuations through temperature compensation function and real-time bus voltage correction, ensuring the accuracy of back EMF detection. In addition, the application of moving average filtering or band-stop filtering eliminates the interference of PWM high-frequency noise on back EMF detection, further improving the threshold determination accuracy. The fault-tolerant mechanism of commutation sequence switching + duty cycle reduction can effectively handle start-up failures caused by commutation conflicts and load overloads, greatly improving the start-up success rate and avoiding the problem of being unable to restart due to a single failure, ensuring the stability and adaptability of the start-up phase.

[0034] In step S130, the MCU outputs a PWM signal to the motor modulator to adjust the duty cycle based on the difference between the real-time speed of the rotor and the target speed, so as to dynamically adjust the real-time speed of the rotor.

[0035] Once the back EMF reaches the target, the MCU switches to closed-loop speed control mode. First, it calculates the real-time rotor speed by detecting the zero-crossing time of the brushless motor's back EMF. Then, it compares the real-time speed with the target speed set by the user and calculates the speed deviation between the two (a negative deviation occurs when the real-time speed is lower than the target speed, and a positive deviation occurs when it is higher than the target speed).

[0036] The MCU processes the speed deviation using a closed-loop speed control algorithm (such as a PI control algorithm): it performs proportional calculations on the speed deviation to quickly respond to the current speed offset, and simultaneously performs integral calculations on the speed deviation to eliminate long-term steady-state deviations, ultimately obtaining the deviation processing result. Based on this result, the PWM duty cycle signal is adjusted. If the real-time speed is lower than the target speed, the PWM duty cycle is increased according to the deviation processing result; if the real-time speed is higher than the target speed, the PWM duty cycle is decreased according to the deviation processing result, and the adjusted PWM signal with the adjusted duty cycle is output to the motor modulator.

[0037] After receiving the PWM signal that adjusts the duty cycle, the motor modulator dynamically adjusts the input power of the brushless motor according to the change in the signal duty cycle (input power increases when the duty cycle increases and decreases when the duty cycle decreases). Through the adjustment of the input power, the output torque of the brushless motor will change synchronously, thereby adjusting the real-time speed of the rotor in real time, so that the rotor speed is stabilized within the preset range of the target speed (such as ±5% of the target speed fluctuation range). Even if there are load changes (such as the increase or decrease of grass resistance during grass cutting), the speed can be maintained through closed-loop regulation.

[0038] The above steps, through closed-loop speed control, calculate the real-time speed based on back EMF zero-crossing detection and dynamically adjust the PWM duty cycle using a PI algorithm. This firstly achieves precise and stable rotor speed during operation. Secondly, by dynamically adjusting the input power of the brushless motor, it can respond in real time to load changes such as increased / decreased grass resistance during cutting, maintaining stable speed without manual intervention. This ensures consistent cutting results and avoids motor overload caused by sudden load changes. Furthermore, this step does not rely on an additional speed sensor, achieving closed-loop control solely through back EMF feedback. This ensures speed control accuracy while further extending the system's low-cost advantage, balancing operational stability, load adaptability, and economy.

[0039] In an optional implementation, during the startup process in step S120, the back electromotive force may fail to meet the standard due to a conflict between the commutation sequence and the rotor magnetic pole direction, or excessive load. In this case, a fault-tolerant mechanism is needed to restore startup and avoid the problem of "unable to restart after startup failure". (1) Handling single startup failures (N≤2) The timer starts from the output of the low duty cycle PWM signal and a preset time is set (based on the motor power: 300ms~500ms for low power motors, 500ms~800ms for high power motors). If the back EMF target is not met after the Nth timeout (N=1 or 2, N≤2), it is determined as a single start failure. At this time, the commutation sequence is automatically switched (e.g., the original sequence U→V→W is switched to U→W→V). The reason is that the original sequence may conflict with the actual magnetic pole direction of the rotor (e.g., the rotor overshoots during positioning, and the magnetic pole direction is reversed). After switching, the new magnetic pole direction can be matched. After switching the commutation sequence, return to step S110, re-output the reverse PWM signal to push the rotor to the preset initial position, and try to start again (to avoid repeated failures caused by direct restart). (2) Handling two consecutive startup failures If two consecutive startups fail (i.e., timeout occurs after two switching of the commutation sequence), it is determined that the initial duty cycle is too high, causing the load to be overloaded. At this time, the initial value of the low duty cycle PWM signal is reduced; and the process returns to step S110 to perform positioning and startup operations. If the startup still fails after the reduction, an alarm is triggered, prompting the user to check the load (such as clearing weeds tangled in the blades).

[0040] The above steps provide targeted recovery strategies for abnormal scenarios that may occur during the startup phase, such as commutation sequence conflicts and load overloads. In the event of a single startup failure (N≤2), the commutation sequence is automatically switched and repositioning is performed, avoiding continuous failures caused by conflicts between the fixed commutation sequence and the actual magnetic pole direction of the rotor, and quickly correcting the startup logic. In the event of two consecutive failures, the initial value of the low-duty-cycle PWM is lowered, reducing the initial thrust of the stator windings, adapting to the startup requirements of heavy-load scenarios, and preventing excessive initial thrust from exacerbating load overload problems. This mechanism significantly improves the startup success rate of the grass-trimming motor under complex operating conditions, avoiding the defect of traditional startup methods where a single failure prevents restarting, enhancing the system's adaptability and robustness to abnormal situations, ensuring the continuity and reliability of the startup process, and reducing manual intervention costs.

[0041] In one optional implementation, the brushless motor start-up vibration optimization system further includes an ADC sampling circuit. During the operation of the brushless motor, the ADC sampling circuit continuously collects the real-time operating current of the brushless motor to monitor the load status of the brushless motor in real time. The MCU compares the real-time operating current collected by the ADC sampling circuit with a preset safety threshold. If the real-time operating current is higher than the preset safety threshold (the preset safety threshold is set based on the rated current of the brushless motor and overload protection requirements), it is determined to be an abnormal current (usually caused by overload, such as when encountering extremely dense weeds that cause a sudden increase in motor resistance).

[0042] When an abnormal real-time operating current is detected, the MCU triggers a protection mechanism. This mechanism includes controlling the brushless motor to brake and decelerate (gradually reducing the PWM duty cycle to decrease input power) or directly stopping the motor (cutting off the motor power supply) to prevent the brushless motor from overheating due to prolonged overload or damaging the power devices. If the brushless motor needs to be restarted subsequently (e.g., manually restarting after stopping, or automatically restarting after the overload is relieved), the process returns to step S110 and repeats the entire process to ensure that jitter issues are avoided on each startup.

[0043] The aforementioned ADC sampling circuit collects motor current in real time, which can accurately identify load overload and avoid the lag of relying on manual monitoring. The "abnormal current → braking deceleration / stop" protection mechanism can effectively prevent the brushless motor from overheating of the windings and damage to power devices due to long-term overload, thus extending the service life of the motor. When restarting, it returns to step S110 to re-execute the complete process, ensuring that the "positioning-smooth start-stable operation" logic is repeated every time it restarts, avoiding secondary jitter caused by changes in rotor position during restart.

[0044] The grass trimmer motor start-up vibration optimization method provided in this application addresses the problems of "start-up vibration, reverse rotation, and start-up failure" in existing sensorless BLDC (Brushless Direct Current) grass trimmer motors. Through a four-stage logic of "initial positioning → throttle start → delay waiting → closed-loop control", it avoids the problems of start-up vibration, reverse rotation, and start-up failure, while ensuring the speed stability during operation. Moreover, it does not require additional sensors, thus balancing control reliability and cost advantages.

[0045] Example 2 like Figure 2 The diagram shown is a structural schematic of a grass-trimming motor start-up vibration optimization system 200 in an embodiment of this application. The system includes an MCU 210, a motor modulator 220, and a brushless motor 230. The brushless motor 230 includes a rotor 231. The MCU210 is used to output a reverse PWM signal, a low duty cycle PWM signal, and an adjustable duty cycle PWM signal to the motor modulator 220 after power-on. The motor modulator 220 is used to push the rotor 231 to a preset initial position according to the reverse PWM signal, control the rotor 231 to start rotating from the preset initial position according to the low duty cycle PWM signal, and dynamically adjust the real-time speed of the rotor 231 according to the adjusted duty cycle PWM signal.

[0046] The grass-trimming motor start-up vibration optimization system provided in this application embodiment can realize each process of the grass-trimming motor start-up vibration optimization method corresponding to Embodiment 1, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0047] Example 3 This application also provides a computer device. Please refer to the following for details. Figure 3 , Figure 3 This is a basic structural block diagram of the computer device in this embodiment.

[0048] The computer device 3 includes a memory 31, a processor 32, and a network interface 33 that are interconnected via a system bus. It should be noted that only a computer device 3 with a memory 31, a processor 32, and a network interface 33 is shown in the figure; however, it should be understood that it is not required to implement all the components shown, and more or fewer components can be implemented alternatively. Those skilled in the art will understand that the computer device described here is a device capable of automatically performing numerical calculations and / or information processing according to pre-set or stored instructions, and its hardware includes, but is not limited to, microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), embedded devices, etc.

[0049] The computer device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The computer device can interact with the user via a keyboard, mouse, remote control, touchpad, or voice control.

[0050] The memory 31 includes at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or D slot compatibility test memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, etc. In some embodiments, the memory 31 may be an internal storage unit of the computer device 3, such as the hard disk or memory of the computer device 3. In other embodiments, the memory 31 may also be an external storage device of the computer device 3, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., equipped on the computer device 3. Of course, the memory 31 may also include both the internal storage unit and its external storage device of the computer device 3. In this embodiment, the memory 31 is typically used to store the operating system and various application software installed on the computer device 3, such as computer-readable instructions for slot compatibility testing methods. In addition, the memory 31 can also be used to temporarily store various types of data that have been output or will be output.

[0051] In some embodiments, the processor 32 may be a central processing unit (CPU), controller, microcontroller, microprocessor, or other mower motor start-up jitter optimization chip. The processor 32 is typically used to control the overall operation of the computer device 3. In this embodiment, the processor 32 is used to execute computer-readable instructions stored in the memory 31 or to process data, such as executing computer-readable instructions for the slot compatibility testing method.

[0052] The network interface 33 may include a wireless network interface or a wired network interface, which is typically used to establish communication connections between the computer device 3 and other electronic devices.

[0053] The computer device provided in this embodiment can execute the above-described method for optimizing the start-up vibration of the mower motor. This method can be any of the mower motor start-up vibration optimization methods described in the various embodiments above.

[0054] Example 4 This embodiment also provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements the steps of the grass-trimming motor start-up vibration optimization method in this embodiment.

[0055] In this embodiment, the computer-readable storage medium includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the computer-readable storage medium can be an internal storage unit of a computer device, such as the hard disk or memory of the computer device. In other embodiments, the computer-readable storage medium can also be an external storage device of the computer device, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the computer device. Of course, the computer-readable storage medium can also include both the internal storage unit and the external storage device of the computer device. In this embodiment, the computer-readable storage medium is typically used to store the operating system and various application software installed on the computer device. In addition, the computer-readable storage medium can also be used to temporarily store various types of data that have been output or will be output.

[0056] In the several embodiments provided in this application, it should be understood that the disclosed systems and methods can also be implemented in other ways. The system embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that, as an alternative implementation, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0057] In addition, the functional modules or units in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0058] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a smartphone, personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium can be a non-volatile storage medium or a volatile storage medium. For example, the storage medium can be a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, or any other medium capable of storing program code.

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for optimizing the starting vibration of a grass-trimming motor, characterized in that, An optimization system for the starting vibration of a mower motor is provided. The system includes an MCU, a motor modulator, and a brushless motor. The brushless motor includes a rotor. The method includes: After the MCU is powered on, the MCU outputs a reverse PWM signal to the motor modulator until the rotor is pushed to the preset initial position; The MCU outputs a low duty cycle PWM signal to the motor modulator to control the rotor to start rotating from the preset initial position until the back electromotive force reaches a preset speed threshold. The duty cycle of the low duty cycle PWM signal is ≤20%, and the preset speed threshold corresponds to the lowest speed at which the brushless motor can identify the zero point of the back electromotive force. The MCU outputs a PWM signal to the motor modulator to adjust the duty cycle based on the difference between the real-time speed of the rotor and the target speed, so as to dynamically adjust the real-time speed of the rotor.

2. The method for optimizing the starting vibration of a grass-trimming motor according to claim 1, characterized in that, The step of the MCU outputting a reverse PWM signal to the motor modulator until the rotor is pushed to a preset initial position includes: After the MCU is powered on, it outputs the reverse PWM signal to the motor modulator and monitors the phase current change rate. When the rate of change of the phase current is detected to be less than a preset rate of change threshold, it is determined that the rotor has reached the preset initial position, and the output of the reverse PWM signal to the motor modulator is stopped.

3. The method for optimizing the starting vibration of a grass-trimming motor according to claim 1 or 2, characterized in that, The step of the MCU outputting a low duty cycle PWM signal to the motor modulator to control the rotor to rotate from the preset initial position until the back electromotive force reaches a preset speed threshold includes: The MCU outputs the low duty cycle PWM signal to the motor modulator, and the motor modulator drives the stator windings of the brushless motor to commutate in a predetermined order according to the low duty cycle PWM signal, so that the rotor gradually accelerates its rotation from the preset initial position. The MCU monitors the back electromotive force in real time. When the peak value of the back electromotive force reaches 10% to 15% of the bus voltage, or the effective amplitude of a single end exceeds 0.2 to 0.3V, it is determined that the back electromotive force has reached the preset speed threshold.

4. The method for optimizing the starting vibration of a grass-trimming motor according to claim 1 or 2, characterized in that, The step of the MCU outputting a low duty cycle PWM signal to the motor modulator to control the rotor to rotate from the preset initial position until the back electromotive force reaches a preset speed threshold also includes: The MCU outputs the low duty cycle PWM signal to the motor modulator to control the rotor to start rotating from the preset initial position; The MCU increases the low duty cycle PWM signal according to a linear or exponential curve, and monitors the back electromotive force of the brushless motor in real time; When the preset conditions are met, it is determined that the back electromotive force reaches the preset speed threshold. The preset conditions include: in multiple consecutive commutation cycles, the period error of the back electromotive force waveform is less than the preset error threshold, which is 3% to 8%.

5. The method for optimizing the starting vibration of a grass-trimming motor according to claim 4, characterized in that, The preset condition also includes: the back electromotive force is greater than or equal to a preset dynamic threshold; in, The preset dynamic threshold, This indicates the proportion of the back electromotive force to the bus voltage under the current bus voltage; This refers to the bus voltage measured in real time. This is a temperature compensation function used to correct the effect of magnetic flux decay on the amplitude of the back electromotive force.

6. The method for optimizing the starting vibration of a mowing motor according to claim 4, characterized in that, While monitoring the back electromotive force of the three phases of the brushless motor in real time, the method also includes: The MCU uses a moving average filter or a band-stop filter to remove PWM noise.

7. The method for optimizing the starting vibration of a mowing motor according to claim 1, characterized in that, The method further includes: If, starting from the time when the low duty cycle PWM signal is output from the MCU to the motor modulator, the back electromotive force still has not reached the preset speed threshold after the Nth time exceeding the preset time, the commutation sequence is automatically switched once, and the reverse PWM signal is output from the MCU to the motor modulator until the rotor is pushed to the preset initial position, where N≤2; If the timing starts from the output of the low duty cycle PWM signal from the MCU to the motor modulator and two consecutive startup failures occur, the low duty cycle PWM signal is reduced, and the MCU returns to outputting the reverse PWM signal to the motor modulator until the rotor is pushed to the preset initial position.

8. A system for optimizing the starting vibration of a grass-trimming motor, characterized in that, Includes an MCU, a motor modulator, and a brushless motor, wherein the brushless motor includes a rotor; The MCU is used to output a reverse PWM signal, a low duty cycle PWM signal, and an adjustable duty cycle PWM signal to the motor modulator after power-on. The motor modulator is used to push the rotor to a preset initial position according to the reverse PWM signal, control the rotor to start rotating from the preset initial position according to the low duty cycle PWM signal, and dynamically adjust the real-time speed of the rotor according to the adjusted duty cycle PWM signal.

9. A computer device, characterized in that, The device includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the grass-trimming motor start-up vibration optimization method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the grass-trimming motor start-up vibration optimization method as described in any one of claims 1-7.

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