Stepping motor control method and device based on pre-tightening and medium

Abstract

The invention discloses a stepping motor control method and device based on pre-tightening, and a medium, and relates to the technical field of stepping motors, and the method comprises the steps: controlling two-phase current to input equal-difference increasing drive current from zero current, so as to enable a rotor to slowly rotate between the two current phases; when the preset force storage time is reached, the driving current rises to a two-phase current intersection point value, and the rotor is positioned at the middle position of the two phases under the mutual exclusion effect of two-phase electromagnetic force; two adjacent phases drive a rotor to rotate in a stepping mode under the mutual exclusion acting force caused by sine / cosine fluctuation current driving, and after a motor power-off signal is received, a driving current is controlled to be adjusted to a two-phase current intersection point value according to the current sine / cosine fluctuation current change trend; and after the rotor is positioned in the middle of the two phases under the action of two-phase electromagnetic mutual exclusion, the driving current is controlled to be reduced to zero current in an equal-difference decreasing trend. Gear collision and current noise during starting are effectively reduced, and starting noise is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of stepper motors, and in particular to a stepper motor control method, device and medium based on pre-tightening. Background Art

[0002] At present, most of the motor drives of automotive air-conditioning outlets on the market are realized by software-controlled PWM (pulse width modulation) waves. This control method can flexibly adjust the speed and position of the motor and is suitable for a variety of different application scenarios. However, the existing PWM control technology has a significant disadvantage: there is no definite position detection mechanism when the motor starts, resulting in the motor being in a free state before each start.

[0003] When the motor starts quickly from a free state, the high-frequency current suddenly applied will cause the motor to accelerate quickly to the target speed, which will generate significant vibration and noise. The specific manifestations are as follows: (1) Noise caused by gear clearance: Since there is a certain clearance between the gears inside the motor (about 0-2 degrees), when the motor starts quickly, the rapid contact between the driving gear and the driven gear will cause a knocking sound. (2) Abnormal noise caused by current: In addition to the collision between mechanical parts, the rapid change of current will also produce a unique current sound.

[0004] These problems not only affect the user's auditory experience, but in the long run may also cause increased wear of the motor's internal components and shorten the motor's service life. Summary of the invention

[0005] In order to make the automobile air-conditioning outlet motor smoother during the startup process and reduce the abnormal noise caused by high-speed gear collision and rapid current change, the present invention proposes a stepper motor control method based on pre-tightening. The operation process of the stepper motor consists of three stages: pre-tightening stage, operation stage, and stop stage. The control method specifically includes the following steps:

[0006] S1: Receive the power-on signal to enter the pre-tightening stage, control the two-phase current to input the driving current with equidistant increment from zero current to make the rotor rotate slowly between the two phases at present;

[0007] S2: When the preset charging time is reached, the driving current rises to the intersection value of the two-phase current, and the rotor is positioned at the middle position between the two phases under the mutual repulsion of the two-phase electromagnetic force;

[0008] S3: Entering the operation stage, the intersection value of the two-phase current is used as the starting current, and the rotor is driven to rotate step by step under the mutual repulsive force caused by the sine / cosine ripple current drive of the adjacent two phases, and enters the S4 step after receiving the motor power-off signal;

[0009] S4: Entering the stop phase, the drive current is controlled to be adjusted to the intersection value of the two-phase current according to the current sine / cosine ripple current change trend, and the rotor is positioned at the middle position between the two phases under the electromagnetic mutual repulsion of the two phases;

[0010] S5: Control and drive the two-phase current to decrease to zero current in an equidistant decreasing trend.

[0011] Furthermore, in the steps S1 and S5, the driving current is controlled to increase or decrease in an arithmetic increment by adjusting the duty cycle of the PWM signal.

[0012] Furthermore, in the steps S1 and S5, the arithmetic increase / decrease of the driving current is expressed by the following formula:

[0013] iHalfPWM=k*T

[0014] Wherein, k is the slope obtained by debugging, T is time, and iHalfPWM is the driving current that changes arithmetic differences with time T.

[0015] Furthermore, the two-phase current alternating point value is the current value corresponding to the sine-cosine intersection point when two adjacent phases of the stator are driven by sine / cosine ripple current.

[0016] Furthermore, in the step S2, the preset charging time is an artificially set time that does not exceed the motor start delay parameter.

[0017] Furthermore, the operation process of the stepper motor also includes a standby stage. In the step S3, after receiving the motor standby signal, the step S3 further includes the following steps:

[0018] S41: Enter the standby stage, control the drive current to adjust to the two-phase current intersection value according to the current sine / cosine ripple current change trend, position the rotor at the middle position between the two phases under the electromagnetic mutual repulsion of the two phases, and after receiving the power-on signal, return to step S3.

[0019] Furthermore, in the step S1, when the rotor does not rotate, abnormal data is reported and the operation is terminated.

[0020] Furthermore, during the execution of step S5, the rotor is maintained at a middle position between the two phases due to the electromagnetic mutual repulsion between the two phases.

[0021] The present invention also includes a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the stepper motor control method based on pre-tightening are implemented.

[0022] Also included is a device for processing data, comprising:

[0023] a memory having a computer program stored thereon;

[0024] A processor is used to execute the computer program in the memory to implement the steps of the stepper motor control method based on pre-tensioning.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] (1) The method, device and medium for controlling a stepper motor based on pre-tightening described in the present invention control the PWM wave through software to give the motor a slowly increasing current before the motor starts, so that the motor gradually accumulates power and is positioned to the middle position between the two phases. This process effectively reduces the gear collision and current noise during startup, and significantly reduces the startup noise;

[0027] (2) Through the preset charging time and current curve, the motor is already in a relatively stable state before formal acceleration, making the starting process smoother and reducing the impact at the moment of starting;

[0028] (3) Smooth start-up during the start-up phase reduces the wear of the motor's internal components and improves the reliability and stability of the system. A similar current control method is used during the stop phase to ensure that the motor can also transition smoothly when it stops, further reducing the wear of mechanical components.

[0029] (4) The smooth start and stop of the motor can be achieved through software control without adding additional hardware costs, thus effectively controlling costs while maintaining high performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A step diagram of a stepping motor control method based on pre-tightening;

[0031] Figure 2 This is the current waveform diagram of the U phase running process of the stepper motor;

[0032] Figure 3 It is a schematic diagram of the stepper motor structure;

[0033] Figure 4 Comparison chart of noise changes before and after improvement. DETAILED DESCRIPTION

[0034] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0035] A stepper motor is an electromechanical device that converts electrical pulse signals into angular or linear displacement. Its working principle is based on the attraction and repulsion characteristics of electromagnets, and the rotation of the rotor is achieved by controlling the power-on sequence of multiple stator windings (i.e. phases) inside the motor.

[0036] During the operation of a traditional stepper motor, after receiving a power-on signal, it will apply a sine / cosine oscillating current to the two stator windings in the current phase interval of the rotor, thereby pushing the rotor to rotate between phases under the action of electromagnetic attraction and repulsion. It is not difficult to see that in this current change process, the current directly fluctuates from zero current according to the trend of the sine / cosine wave. Combined with the understanding of the sine / cosine waveform, its initial current change trend is undoubtedly very large compared to the entire waveform, which leads to current noise at startup. Coupled with the uncertainty of the rotor starting position, when the rotor is suddenly tightened from a free state under the action of electromagnetic force, air friction and possible gear collisions will occur, further exacerbating the abnormal noise at startup. Therefore, if the rotor can be pre-tightened before formal startup, and at the same time, the initial fluctuation amplitude of the current is reduced, the noise caused by this can be reduced. Under this idea, in order to reduce the noise during the motor startup process, such as Figure 1 As shown, the present invention proposes a stepper motor control method based on pre-tightening. In the present invention, the operation process of the stepper motor is mainly divided into three stages: pre-tightening stage, operation stage and stop stage. In these three stages, the starting noise is eliminated by different current waveform changes. The specific steps are as follows:

[0037] S1: Receive the power-on signal to enter the pre-tightening stage, control the two-phase current to start from zero current and input the driving current with equidistant increment to make the rotor rotate slowly between the two phases at present;

[0038] S2: When the preset charging time is reached, the driving current rises to the intersection value of the two-phase current, and the rotor is positioned at the middle position between the two phases under the mutual repulsion of the two-phase electromagnetic force;

[0039] S3: Entering the operation stage, the intersection value of the two-phase current is used as the starting current, and the rotor is driven to rotate step by step under the mutual repulsive force caused by the sine / cosine ripple current drive of the adjacent two phases, and enters the S4 step after receiving the motor power-off signal;

[0040] S4: Entering the stop phase, the drive current is controlled to be adjusted to the intersection value of the two-phase current according to the current sine / cosine ripple current change trend, and the rotor is positioned at the middle position between the two phases under the electromagnetic mutual repulsion of the two phases;

[0041] S5: Control and drive the two-phase current to decrease to zero current in an equidistant decreasing trend.

[0042] In the present invention, in order to solve the noise caused by current mutation, after receiving the motor power-on signal, the driving current does not directly change with the change trend of the sine / cosine wave, but starts from zero current and gradually increases the driving current in an arithmetic increment manner.

[0043] Specifically, after receiving the motor power-on signal, the drive current is not immediately adjusted in the form of a sine wave or cosine wave, but a smoother transition method is adopted: starting from zero current, the drive current is gradually increased in an arithmetic increment. This strategy effectively avoids electromagnetic noise caused by current mutations, making the motor startup process smoother and quieter.

[0044] In addition, this method also introduces a clever design during implementation: applying drive currents of the same magnitude and direction to the two phases where the rotor is currently located. The purpose of this is to use the mutual repulsion between the two phases to cause the rotor to slowly rotate to the middle position between the two phases and achieve "tightening" at this position. The so-called "tightening" means that under the action of this electromagnetic mutual repulsion, the rotor is stably maintained in the middle position, reducing any unnecessary vibration or deviation that may be caused by current fluctuations. In this way, not only the stability of the motor operation is improved, but also the service life of the motor is extended.

[0045] In order to avoid the rotor swing caused by the left and right fluctuations of electromagnetic force after the rotor is officially started, the cut-off current of the drive current is set according to the current value at the intersection of the sine / cosine oscillating current used during operation. In this process, the current change trend can be expressed by the following formula:

[0046] iHalfPWM=k*T

[0047] In the formula, k is the slope obtained through debugging, T is time, and iHalfPWM is the driving current that changes arithmetic with time T. It should be noted that in order not to affect the normal operation of the stepper motor, the artificially set preset charging time cannot exceed the motor start delay parameter.

[0048] In this way, by setting the incremental cut-off current at these intersections, the continuity of the current change rate can be ensured, making the change of the electromagnetic force smoother, thereby effectively avoiding the swing of the rotor after startup. At the same time, since the current value at the intersection is usually the key point of the waveform change, using these points as a reference can make the drive current more accurately match the actual working requirements and improve the overall performance of the motor. This is adopted in this way, which can not only reduce unnecessary mechanical stress and wear, but also significantly improve the stability and reliability of motor operation, especially in application scenarios that require high-precision positioning.

[0049] Furthermore, if Figure 2 As shown in Figure 1, the start-up and operation of stepper motors involve complex current control mechanisms. Considering the existence of the stepper motor's operating current, the drive current must reach a certain threshold value before the motor actually starts to rotate. If the drive current is lower than this operating current value, the stepper motor will not start even if a drive signal is applied.

[0050] Therefore, in order to ensure that the motor can start smoothly and enter a stable running state, after receiving the start signal, the drive current must first be quickly increased to the operating current value required by the stepper motor. This process is achieved by quickly increasing the drive current to ensure that the motor can obtain enough power in the shortest time to overcome static friction and start rotating. This method not only improves the response speed of the motor, but also effectively reduces the startup delay, allowing the motor to enter the working state at the first time.

[0051] Once the drive current reaches the operating current value and the motor starts to rotate, the pre-tensioning phase begins. In this phase, the drive current is no longer constant, but increases gradually from the current operating current value in an arithmetic increment.

[0052] This two-stage drive current control method combines the advantages of fast startup with the requirements of smooth operation, ensuring that the motor can start quickly while ensuring its stability and accuracy in subsequent operation.

[0053] When the rotor is positioned in the middle of the two phases within the preset charging time, the stepper motor officially enters the operation stage. At this time, the preset starting current is used as the starting current, and the adjacent two-phase stator windings generate electromagnetic fields under the action of sine wave or cosine wave driving current. These fluctuating currents not only provide the necessary driving force, but also achieve precise control of the rotor position by precisely controlling the changes in the magnetic field.

[0054] Specifically, the electromagnetic fields generated by each stator winding interact with each other to form a repulsive force. This repulsive force causes the rotor to gradually move to the next position under the action of the stator magnetic field, thereby achieving step-by-step rotation. In this way, the stepper motor can accurately rotate a fixed angle (step angle) under the action of each pulse signal, which enables the motor to provide high-precision position control in various application scenarios.

[0055] After receiving the motor power-off signal and entering the stop phase, the control system first analyzes the current driving current's sine wave or cosine wave change trend, and continues to adjust the driving current change according to this trend. Specifically, the system will adjust the driving current according to the existing current waveform, so that it gradually changes to the intersection value of the two-phase current. This intersection value is the position where the current waveforms of two adjacent stator windings intersect, representing the state of electromagnetic force balance.

[0056] In this way, the rotor can gradually move to the middle position between the two phases under the action of electromagnetic mutual repulsion. This design not only avoids mechanical shock and vibration caused by current mutation, but also ensures that the rotor is directly positioned in the ideal position after shutdown, thereby improving the stability and accuracy of the system.

[0057] Once the rotor is precisely positioned in the middle of the two phases, the next step is to gradually reduce the drive current so that it decreases smoothly from the current value to zero current. Specifically, similar to the pre-tightening stage, starting from the intersection value of the two-phase current, the drive current gradually decreases according to a fixed decreasing step. When the drive current drops to zero, while ensuring that the rotor always remains stably in the middle of the two phases, the system will completely cut off the power supply, complete the shutdown process, and achieve noise reduction during the stop phase.

[0058] By keeping the rotor at the middle position between the two phases after stopping, the motor only needs to be supplied with a very small holding current to allow the motor to accumulate power after stopping, without the need to perform positioning operations.

[0059] In the whole motor control process, taking two-phase five-pole pairs (step angle 18°) as an example, the rotor rotates toward the middle position between the two phases, and at most travels half a step angle of 9° between the two phases (such as Figure 3 As shown in the figure, the transmission ratio (three-pole linkage meshing gear) is reduced to only 0.05625 / 2° on the output shaft, while the meshing clearance of the two gears in the free state is about 2°. It can be seen that during the positioning process, there is a high probability that the gears will not collide. Even if there is a collision, the current is small and the speed is low during the positioning stage, and the collision is also the sound of normal gear meshing at a low speed, which can be weakened by the housing.

[0060] According to actual use requirements, in addition to the three stages of pre-tightening stage, running stage and stopping stage, a standby stage may also be included. In step S3, after receiving the motor standby signal, the following steps are also included:

[0061] S41: Enter the standby stage, control the drive current to adjust to the two-phase current intersection value according to the current sine / cosine ripple current change trend, position the rotor at the middle position between the two phases under the electromagnetic mutual repulsion of the two phases, and after receiving the power-on signal, return to step S3.

[0062] If the rotor cannot rotate normally in step S1, it is determined that the stepper motor is operating abnormally, the abnormal data is uploaded and the operation is terminated.

[0063] In a specific embodiment, the stepper motor control method proposed in the present invention is used for drive control. When the same actuator is started under the same environment with the same acceleration and the same target speed, the following is obtained: Figure 4 The noise curve comparison chart shown (the horizontal axis is time (unit s), the vertical axis is noise (unit dB)), where the green line is the noise change curve before improvement, and the red line is the noise change curve after improvement. It can be seen that the startup noise has been significantly improved after improvement.

[0064] The present invention also includes a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the stepper motor control method based on pre-tightening are implemented.

[0065] Also included is a device for processing data, comprising:

[0066] a memory having a computer program stored thereon;

[0067] A processor is used to execute the computer program in the memory to implement the steps of the stepper motor control method based on pre-tensioning.

[0068] In summary, the present invention proposes a pre-tightening-based stepper motor control method, device and medium. Before the motor starts, the software controls the PWM wave to give the motor a slowly increasing current, so that the motor gradually accumulates power and positions itself to the middle position between the two phases. This process effectively reduces the gear collision and current noise during startup, and significantly reduces the startup noise.

[0069] Through the preset charging time and current curve, the motor is already in a relatively stable state before formal acceleration, making the starting process smoother and reducing the impact at the moment of starting.

[0070] The smooth start-up during the starting phase reduces the wear of the motor's internal components and improves the reliability and stability of the system. A similar current control method is used during the stopping phase to ensure that the motor can also transition smoothly when stopping, further reducing the wear of mechanical parts.

[0071] The smooth start and stop of the motor can be achieved through software control without adding additional hardware costs, thus effectively controlling costs while maintaining high performance.

[0072] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0073] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0074] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0075] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A stepper motor control method based on pre-tightening, characterized in that: The operation process of the stepper motor consists of three stages: pre-tightening stage, operation stage, and stop stage. The control method specifically includes the following steps: S1: Receive the power-on signal to enter the pre-tightening stage, control the two-phase current to start from zero current and input the driving current with equidistant increment to make the rotor rotate slowly between the two phases at present; S2: When the preset charging time is reached, the driving current rises to the intersection value of the two-phase current, and the rotor is positioned at the middle position between the two phases under the mutual repulsion of the two-phase electromagnetic force; S3: Entering the operation stage, the intersection value of the two-phase current is used as the starting current, and the rotor is driven to rotate step by step under the mutual repulsive force caused by the sine / cosine ripple current drive of the adjacent two phases, and enters the S4 step after receiving the motor power-off signal; S4: Entering the stop phase, the drive current is controlled to be adjusted to the intersection value of the two-phase current according to the current sine / cosine ripple current change trend, and the rotor is positioned at the middle position between the two phases under the electromagnetic mutual repulsion of the two phases; S5: Control and drive the two-phase current to decrease to zero current in an equidistant decreasing trend.

2. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: In the steps S1 and S5, the driving current is controlled to increase or decrease in arithmetic increments by adjusting the duty cycle of the PWM signal.

3. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: In the steps S1 and S5, the arithmetic increase / decrease of the driving current is expressed by the following formula: iHalfPWM=k*T Wherein, k is the slope obtained by debugging, T is time, and iHalfPWM is the driving current that changes arithmetic differences with time T.

4. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: The two-phase current alternating point value is the current value corresponding to the sine-cosine intersection point when two adjacent phases of the stator are driven by sine / cosine ripple current.

5. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: In the step S2, the preset charging time is an artificially set time that does not exceed the motor start delay parameter.

6. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: The operation process of the stepper motor also includes a standby stage. In the step S3, after receiving the motor standby signal, the following steps are also included: S41: Enter the standby stage, control the drive current to adjust to the intersection value of the two-phase current according to the current sine / cosine ripple current change trend, position the rotor at the middle position of the two phases under the electromagnetic mutual repulsion of the two phases, and return to step S3 after receiving the power-on signal.

7. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: In the step S1, when the rotor does not rotate, abnormal data is reported and the operation is terminated.

8. A stepper motor control method based on pre-tightening as claimed in claim 1, characterized in that: During the execution of step S5, the rotor is kept at the middle position between the two phases due to the electromagnetic mutual repulsion between the two phases.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the control method described in any one of claims 1 to 8 are implemented.

10. A device for processing data, characterized in that: include: a memory having a computer program stored thereon; A processor, configured to execute the computer program in the memory to implement the steps of the control method according to any one of claims 1 to 8.

Images