Apparatus based on stepper motor driving and its brake control method and system

Abstract

This invention discloses a braking control method based on a stepper motor drive, comprising: controlling the stepper motor's braking device to be in a closed state during the initial power-on phase; smoothly and gradually increasing the motor current curve to a first holding current, and opening the braking device after reaching this current; waiting for a first preset time, then reducing the current to a second holding current, and waiting for a second preset time, then increasing it back to the first holding current for gear calibration; after gear calibration, waiting for a third preset time, clearing the encoder and starting counting; waiting for a fourth preset time, then controlling the stepper motor to perform micro-oscillation calibration; after calibration, smoothly and gradually reducing the motor current curve to a rated value, and determining whether a stable state has been reached; after reaching a stable state, adjusting the motor's operating position and speed according to instructions. This invention effectively solves the problem of shaft drop under heavy load power-on through reasonable timing and current coordination, ensuring initial zero-position accuracy and smooth start-up, and improving the reliability of braking control.

Description

Technical Field

[0001] This invention belongs to the technical field of equipment braking control methods, specifically relating to a device based on stepper motor drive and its braking control method and system. Background Technology

[0002] With the continuous advancement of industrial automation technology, stepper closed-loop motors, due to their high positioning accuracy and fast response speed, are widely used in heavy-load drive and braking control scenarios, including automated equipment, material handling equipment, and CNC machine tools. Heavy equipment places extremely stringent requirements on the braking control logic of stepper closed-loop motors. The system not only needs to ensure the positional stability of the motor during start-up, shutdown, and operation, but also must effectively overcome the adverse effects of load gravity to prevent safety accidents such as shaft detachment.

[0003] Currently, stepper closed-loop drive systems with braking devices generally employ a basic control logic of locking the brake upon power-on and releasing it directly upon enabling. This primarily relies on hardware circuitry to achieve simple linkage between the braking device and the motor drive. However, this traditional control method has many limitations in practical applications: First, the adaptability to heavy loads is poor during the power-on phase. When powered on under heavy load conditions, the motor has not yet established a stable driving force sufficient to overcome the gravitational torque. If the brake is released directly or the current is applied improperly at this time, the encoder is very likely to produce a large initial deviation due to the load gravity, causing the motor to experience shaft slippage, vertical movement, or high-frequency vibration. It is unable to quickly establish a stable initial state, which seriously threatens the safety and stability of the equipment during startup.

[0004] Secondly, there is a lack of effective protection against sudden abnormal situations. During equipment operation, if a sudden power outage or abnormal power failure occurs, traditional braking control mechanisms often have a response lag, and the braking device cannot close instantly. At this time, the motor loses its braking constraint, and the load's gravity acts directly on the motor shaft, which can easily lead to a shaft drop accident, causing damage to the equipment's mechanical structure or scrapping the products it carries.

[0005] Secondly, the coordination between the motor and encoder is insufficient. Existing technologies typically lack a precise calibration mechanism for the motor rotor zero position and the encoder counting start point during the startup phase, resulting in a significant zero-position correspondence deviation between the two in the initial state. This deviation persists into subsequent operation, causing positioning errors and making it difficult to meet the requirements of high-precision operations.

[0006] Finally, traditional improvement solutions are costly and suffer from latency. To address the aforementioned braking and positioning issues, existing technologies often compensate by adding extra hardware detection modules or optimizing the mechanical structure. This approach not only significantly increases the manufacturing cost of a single device, but also inevitably introduces latency in signal transmission and processing at the hardware level, making it difficult to achieve highly responsive brake and motor coordinated control. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of unstable power-on of stepper closed-loop motor, sudden abnormal shaft drop and poor initial positioning accuracy in braking scenarios of heavy-load equipment in the prior art, so as to provide a braking control method for equipment based on stepper motor drive.

[0008] A braking control method based on stepper motor drive includes the following steps: Step S1: During the initial power-on phase, the braking device controlling the stepper motor is in the off state; Step S2: Smoothly and gradually increase the motor current curve to the first holding current, and open the brake device after reaching the first holding current; Step S3: After opening the brake device, wait for a first preset time, reduce the motor current to a second holding current; after reaching the second holding current, wait for a second preset time, increase the motor current to the first holding current, and perform gear calibration; Step S4: After calibrating the teeth, wait for the third preset time, clear the current encoder count value and related position variables to zero, and start encoder counting; Step S5: After starting the encoder counting, wait for the fourth preset time, and control the stepper motor to perform a small oscillation calibration; Step S6: After the micro-oscillation calibration is completed, the motor current curve is smoothly and gradually reduced to the rated value, and it is determined whether the stepper motor has reached a stable state. Step S7: After the stepper motor reaches a stable state, it enters normal operation and adjusts the position and speed of the motor according to the instructions.

[0009] The first holding current is greater than the second holding current, and the second holding current is greater than the rated current of the stepper motor; the first preset time, the second preset time, the third preset time, and the fourth preset time are preset fixed times.

[0010] Furthermore, the micro-oscillation calibration includes: The motor is controlled to swing forward and backward at a preset swing angle and preset speed; During the oscillation process, the actual rotation angle signal of the motor is acquired in real time through the encoder; The deviation value is calculated by comparing the actual rotation angle signal with the preset number of pulses corresponding to the preset swing angle. If the actual angle value is less than the preset value, the number of output pulses is increased; if the actual angle value is greater than the preset value, the number of output pulses is decreased. After the oscillation cycle ends, the motor is controlled to return to its initial zero position.

[0011] Furthermore, the specific method for determining whether the stepper motor has reached a stable state is as follows: Real-time monitoring of motor winding current fluctuations and motor shaft angle changes; If, within a continuously preset monitoring period after the given rated current, the winding current fluctuation value is within the range of rated current value ± preset current deviation, and the change in motor shaft rotation angle detected by the encoder is within the range of preset pulse deviation, then the motor is determined to have reached a stable state. Otherwise, the latest encoder count value is used as the initial count value, and the stable state is re-evaluated.

[0012] Furthermore, after the stepper motor reaches a stable state, the normal operating state includes routine handling: The motor current is at its rated value, and the brake device is in the open state; When communication is not possible or the device is not enabled, the motor current remains at the rated value and the brake device remains in the open state.

[0013] Furthermore, after the stepper motor reaches a stable state, the normal operating state includes general alarm handling: When the detected deviation value is greater than the first preset pulse threshold, the device is in the enabled state and the actual speed feedback is 0, and the stall duration exceeds the first preset duration, a stall alarm is triggered. When the actual position of the motor deviates from the target position by more than a preset number of revolutions, an over-tolerance alarm is triggered. When a general alarm is triggered, the brake device is closed first, and then the motor drive current is cut off. Upon receiving a program reset operation, the motor drive current is first returned to its rated value before the brake device is activated.

[0014] Furthermore, after the stepper motor reaches a stable state, the normal operating state includes critical alarm handling: When the motor phase current is detected to be less than the second preset current threshold, it is determined to be a motor phase loss alarm; When the motor current is detected to be greater than the third preset current threshold and continues for more than the second preset time, it is determined to be a motor overcurrent alarm; When the power supply voltage is detected to be less than the first preset voltage threshold or greater than the second preset voltage threshold, it is determined to be an undervoltage or overvoltage alarm. When a serious alarm is triggered, the brake device is first closed and then the motor drive current is cut off. It cannot be reset by the program and a power outage inspection is required.

[0015] Furthermore, after the stepper motor reaches a stable state, the normal operating state includes handling sudden power outages: Real-time monitoring of power supply voltage; When the voltage drops sharply from the rated value to below the preset power-off voltage threshold and the duration reaches the third preset duration, it is determined to be a power-off abnormality. When a power outage is detected, a brake closing signal is first sent to control the brake device to close, and then the motor drive current is cut off.

[0016] Furthermore, the first holding current is a first current ratio of the motor's rated current, the second holding current is a second current ratio of the motor's rated current, and the first current ratio is greater than the second current ratio.

[0017] A brake control system based on stepper motor drive, used to execute the above method, includes: A closed-loop stepper motor module with brake, comprising a stepper motor, an electromagnetic brake device, and an incremental encoder; The driver module includes a data processing module, a communication module, a voltage detection module, a brake signal output interface, a motor current output interface, and an encoder signal input interface; The power supply module is connected to the driver module; The host computer module is connected to the driver module through the communication module; The voltage detection module is connected in parallel to the power supply circuit and is connected to the data processing module; the brake signal output interface is connected to the electromagnetic brake device; the motor current output interface is connected to the stepper motor; and the encoder signal input interface is connected to the incremental encoder.

[0018] A stepper motor driven device includes a device body, a motion execution component, and the aforementioned stepper motor driven brake control system. The motion execution component is mounted on the device body, and the stepper motor module with brake closed loop is mounted on the device body or the motion execution component. The output shaft of the stepper motor is connected to the motion execution component for driving the device body to run. The electromagnetic brake device is fixed coaxially with the output shaft of the stepper motor, and the incremental encoder is installed at the tail of the stepper motor. The driver module and the power module are fixed inside the device body and are electrically connected to the stepper motor module with brake closed loop. The host computer module is deployed in the control area of ​​the device body and is used to receive braking or control commands from the operator and send them to the data processing module through the communication module.

[0019] Beneficial Effects: This invention discloses a braking control method based on a stepper motor drive. The braking device is closed at the initial power-on stage, mechanically constraining the motor shaft. The brake is only released after the motor current curve smoothly and gradually increases to the first holding current, ensuring that the motor establishes sufficient holding torque to overcome the load before releasing the mechanical brake. This control logic avoids the risks of shaft slippage, vibration, or surging during power-on under heavy load scenarios, greatly improving the safety of equipment startup. Furthermore, the smooth and gradual current increase avoids the impact of sudden current changes on the motor windings.

[0020] After the brake is released, the present invention controls the motor current to switch between the first holding current and the second holding current to perform tooth calibration. The change in magnetic force is used to make the motor rotor reach a stable balance position. Then, at a specific time, the current count value of the encoder and related position variables are cleared to zero and the counting is started, so that the zero position of the encoder is accurately unified with the mechanical stable balance position of the motor, eliminating the initial zero position deviation and fundamentally improving the positioning accuracy of subsequent operation.

[0021] This invention introduces a micro-oscillation calibration after zeroing the encoder, and then smoothly and gradually reduces the motor current curve to the rated value after calibration. Simultaneously, it rigorously checks whether the motor has reached a stable state, only entering normal operation after confirmation of stability. This process ensures that the motor is in a highly stable state before entering formal operation, avoiding sudden position changes due to state switching, and achieving a smooth and reliable start-up transition. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart of the main method steps of the present invention. Detailed Implementation

[0024] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0025] In the description of this application, it should be understood 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 at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] Example 1: Reference Figure 1 As shown, this embodiment provides a braking control method based on stepper motor drive. This method achieves smooth start-stop and safe braking through optimized software collaborative logic, and specifically includes the following steps.

[0028] Step S1: During the initial power-on phase, the braking device controlling the stepper motor is in the off state. During this phase, the brake pads of the electromagnetic brake device are in close contact with the motor output shaft, providing a braking torque greater than or equal to 3 N·m. This prevents the shaft from falling off under heavy loads such as 10 kg, ensuring equipment safety during the initial startup phase.

[0029] Step S2: Smoothly and gradually increase the motor current curve to the first holding current, and open the brake device after reaching the first holding current.

[0030] Specifically, in this embodiment, the drive module outputs the motor current according to a preset function model. Taking a motor rated current of 6A as an example, the preset function model yields y=ln(x / 200+0.005)+6, with the curve changes within 1000ms as follows: 0.70A at 0ms, 6.01A at 200ms, 6.70A at 400ms, 7.10A at 600ms, 7.39A at 800ms, 7.5A at 895ms, and 7.61A at 1000ms. The maximum current change does not exceed the first holding current, and the motor current no longer increases after reaching the first holding current at 895ms. The drive module starts timing when the motor winding current reaches the first holding current in real time, and after 100ms, it releases the brake. At this time, the static torque of the motor itself provides a torque constraint of greater than or equal to 8 N·m on the motor shaft. Using a smooth, gradual current boost curve can avoid overheating or severe vibration of the windings caused by instantaneous high current surges, allowing the motor torque to increase steadily and gradually overcome the load torque.

[0031] In a preferred embodiment, the preset function model is a logarithmic function with time as the independent variable, the output motor current as the dependent variable, the motor's rated current as , and the motor's own rated current in amperes as the base value. Specifically, it is set as y = ln(x / 200 + 0.005) + b, where x is the time in milliseconds, b is the motor's own rated current in amperes, and y is the output motor current in amperes that varies with time x.

[0032] Step S3: After opening the brake device, wait for the first preset time, reduce the motor current to the second holding current; after reaching the second holding current, wait for the second preset time, increase the motor current to the first holding current, and perform gear calibration.

[0033] Specifically, in this embodiment, 100ms after the brake is engaged, the output current of the drive module immediately decreases to the second holding current. When the drive module detects that the motor winding current has reached the second holding current, it starts timing, waits 200ms, and then increases the motor current to the first holding current. Since the magnetic field strength is proportional to the winding current, the decrease in motor current from the first holding current to the second holding current and then back to the first holding current causes the magnetic force on the rotor to weaken and then strengthen. This causes the stepper motor to rotate an angle under the influence of the magnetic field, aligning its tooth axis with the tooth axis of the stator magnetic poles, achieving a stable equilibrium position, thereby improving the positioning accuracy during subsequent operation.

[0034] Step S4: After calibrating the teeth, wait for the third preset time, clear the current encoder count value and related position variables to zero, and start the encoder counting.

[0035] Specifically, in this embodiment, after the motor current increases to the first holding current and 100ms have elapsed, the drive module sends a zeroing command to clear the current encoder count value and related position variables such as cumulative rotation angle and deviation value to ensure that the encoder counting start point 0 position is consistent with the motor tooth alignment position. Then the encoder counting function is started. At this time, the motor shaft position and the encoder count value are both initialized to 0, eliminating the initial zero position deviation.

[0036] Step S5: After starting the encoder counting, wait for the fourth preset time, and control the stepper motor to perform a small oscillation calibration.

[0037] In this embodiment, the first holding current is greater than the second holding current, and the second holding current is greater than the rated current of the stepper motor; the first preset time, the second preset time, the third preset time, and the fourth preset time are preset fixed times.

[0038] Specifically, in this embodiment, after the encoder-related variables are cleared to zero, the drive module outputs a pulse signal after 100ms to control the motor to swing forward and backward at a preset swing angle and preset speed. For example, it swings at a swing angle of ±3.6 degrees and a speed of 1r / min, that is, swings forward for 0.6s and swings backward for 0.6s. During the swinging process, the motor output current is controlled by the first holding current.

[0039] During the oscillation process, the encoder collects the actual rotation angle signal of the motor in real time and transmits it to the drive module. The drive module compares the actual rotation angle signal with the preset number of pulses corresponding to the preset oscillation angle to calculate the deviation value. For example, when the encoder resolution is 1000 lines, ±3.6 degrees corresponds to ±40 pulses.

[0040] If the actual rotation angle is less than the preset value, the drive module increases the number of output pulses; if the actual rotation angle is greater than the preset value, the number of output pulses decreases. Each adjustment step is 1 pulse, ensuring that the deviation between the motor rotation angle and the encoder count value during the oscillation is less than or equal to 1 pulse. After the oscillation cycle ends, the motor is controlled to return to the initial zero position, achieving high-precision correspondence through precise pulse adjustment.

[0041] Step S6: After the micro-oscillation calibration is completed, the motor current curve is smoothly and gradually reduced to the rated value, and it is determined whether the stepper motor has reached a stable state.

[0042] Specifically, in this embodiment, the drive module outputs the motor current according to a preset function model y=-ln(x / 200+0.005)+b. Taking the rated motor current of 6A as an example, applying the formula, we get y=-ln(x / 200+0.005)+6. The curve changes within 1000ms as follows: 11.30A at 0ms, 7.50A at 43ms, 6.00A at 200ms, 5.30A at 400ms, 4.90A at 600ms, 4.61A at 800ms, and 4.39A at 1000ms. The maximum current change does not exceed the first holding current of 7.5A, and the minimum does not fall below the rated value of 6A. That is, within the time period from 43ms to 200ms, the current smoothly and gradually decreases from the first holding current curve to the rated value. This gradual decrease allows for a smooth transition of motor torque and reduces the possibility of sudden position changes.

[0043] The specific method for determining whether a stepper motor has reached a stable state is as follows: real-time monitoring of the fluctuation value of the motor winding current and the change in motor shaft angle. The winding current I is measured by ADC to obtain the voltage drop V when the winding current I flows through the sampling resistor R, and is calculated by I=V / R. The change in motor shaft angle is obtained by the MCU timer through hardware decoding to convert the A-phase and B-phase pulses generated by the encoder into count values.

[0044] Within a continuously preset monitoring period after the given rated current, i.e., within 500 ms, the real-time winding current is checked every 65.2 µs. If the winding current fluctuation is within the range of ±0.1A (rated current ± preset current deviation), and the encoder count is checked every 62.5 µs, with the encoder detecting a change in motor shaft angle within a preset pulse deviation range (less than or equal to ±1 pulse), then the motor is considered to have reached a stable state. If the above conditions are not met, the latest encoder count is used as the initial count, and the stability state is re-evaluated to ensure that the motor is in a highly stable state before entering normal operation.

[0045] Step S7: After the stepper motor reaches a stable state, it enters normal operation and adjusts the motor's position and speed according to the instructions.

[0046] Specifically, in this embodiment, normal operation includes handling under normal conditions. After the stepper motor reaches a stable state, the motor current is at its rated value, and the brake device is in the open state. When communication is not possible or the brake device is not enabled, the motor current remains at its rated value and the brake device remains in the open state to avoid potential positional deviations caused by unnecessary braking and closing under heavy load conditions.

[0047] Normal operation also includes general alarm handling. When the detected deviation value is greater than the first preset pulse threshold, the motor is in the enabled state and the actual speed feedback is 0, or the stall duration exceeds the first preset duration, a stall alarm is triggered, for example, when the deviation value is greater than 30 pulses and the stall lasts for more than 3 seconds; when the actual position of the motor deviates from the target position by more than a preset number of revolutions, an over-tolerance alarm is triggered, for example, when the deviation exceeds 1 revolution.

[0048] When a general alarm is triggered, the brake device is closed first, and then the motor drive current is cut off. The time for the current to drop from the operating value to 0 should not exceed 5ms to prevent shaft drop. After receiving a program reset operation, the motor drive current is first returned to the rated value, and then the brake device is opened to resume normal operation and prepare to receive control commands.

[0049] Normal operation also includes critical alarm handling. When the detected motor phase current is less than the second preset current threshold, it is judged as a motor phase loss alarm, for example, when the phase current is less than 0.1A; when the detected motor current is greater than the third preset current threshold and lasts for more than the second preset duration, it is judged as a motor overcurrent alarm, for example, when the current is greater than 20A and lasts for more than 1ms; when the detected supply voltage is less than the first preset voltage threshold or greater than the second preset voltage threshold, it is judged as an undervoltage or overvoltage alarm, for example, when the voltage is less than 18V or greater than 100V.

[0050] When a serious alarm is triggered, the brake device will be closed first, and then the motor drive current will be cut off. The time for the current to drop from the operating value to 0 will not exceed 5ms, and it cannot be reset by the program. Power must be turned off for inspection. Power can only be turned on after there is no abnormality, to ensure that the equipment is not seriously damaged.

[0051] Normal operation also includes handling sudden power outages. The power supply voltage is monitored in real time; when the voltage drops sharply from the rated value to below the preset power outage voltage threshold and the duration reaches the third preset duration, it is determined to be a power outage anomaly, for example, when the voltage drops sharply from 70VAC to below 60VAC and lasts for 1ms.

[0052] When a power outage is detected, a brake closing signal is first sent to control the brake device to close, and then the motor drive current is cut off. The time for the current to drop from the operating value to 0 does not exceed 5ms. After the brake is closed, the braking torque is greater than or equal to 3N·m, thereby effectively avoiding shaft drop accidents caused by sudden power outages.

[0053] Furthermore, the aforementioned first holding current is a first current ratio of the motor's rated current, and the second holding current is a second current ratio of the motor's rated current, with the first current ratio being greater than the second current ratio. For example, the first current ratio is 125%, and the second current ratio is 110%, thereby achieving effective changes in the magnetic field force through a reasonable current step setting.

[0054] Example 2: This embodiment provides a brake control system based on stepper motor drive for executing the above method. The system includes a stepper motor module with brake closed-loop, a driver module, a power supply module, and a host computer module.

[0055] The stepper motor module with brake closed loop includes a stepper motor, an electromagnetic brake device, and an incremental encoder.

[0056] The driver module includes a data processing module, a communication module, a voltage detection module, a brake signal output interface, a motor current output interface, and an encoder signal input interface.

[0057] The power supply module connects to the driver module to supply power to the entire system, with a supply voltage of, for example, 70VAC. The host computer module connects to the driver module via a communication module, for example, an EtherCAT controller, to achieve real-time data interaction.

[0058] The connections between the components are as follows: the voltage detection module is connected in parallel to the power supply circuit and to the data processing module to acquire and transmit the power supply voltage signal in real time; the brake signal output interface is connected to the electromagnetic brake device to control the opening and closing of the brake; the motor current output interface is connected to the stepper motor to provide drive current for the motor; and the encoder signal input interface is connected to the incremental encoder to receive the position signal fed back from the encoder. Through the close cooperation of these modules, the system achieves high-response brake and motor coordinated control without the need for additional hardware.

[0059] Example 3: This embodiment provides an industrial automation device based on stepper motor drive, including a device body, motion execution components, and the aforementioned brake control system for the stepper motor driven device.

[0060] The motion execution component is mounted on the device body, and the stepper motor module with brake closed loop is mounted on the device body or the motion execution component. The output shaft of the stepper motor is connected to the motion execution component for driving the device body to run. The electromagnetic brake device is fixed coaxially with the output shaft of the stepper motor, and the incremental encoder is installed at the tail of the stepper motor. The driver module and the power module are fixed inside the device body and are electrically connected to the stepper motor module with brake closed loop. The host computer module is deployed in the control area of ​​the device body and is used to receive braking or control commands from the operator and send them to the data processing module through the communication module.

[0061] In other embodiments of the present invention, the braking control system of the stepper motor driven device can also be applied to heavy-duty vehicles, wherein the stepper motor drives the vehicle and the braking control of the vehicle is achieved in the manner described above.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A braking control method based on stepper motor drive, characterized in that, Includes the following steps: During the initial power-on phase, the brake device controlling the stepper motor is in the off state; the motor current curve is smoothly and gradually increased to the first holding current, and the brake device is opened after reaching the first holding current; after the brake device is opened, wait for a first preset time, and then reduce the motor current to the second holding current; after reaching the second holding current, wait for a second preset time, and then increase the motor current to the first holding current for tooth calibration; after tooth calibration, wait for a third preset time, clear the current encoder count value and related position variables to zero, and start encoder counting; after starting encoder counting, wait for a fourth preset time, and control the stepper motor to perform micro-oscillation calibration; after the micro-oscillation calibration is completed, the motor current curve is smoothly and gradually reduced to the rated value, and it is determined whether the stepper motor has reached a stable state; After the stepper motor reaches a stable state, the position and speed of the motor are adjusted according to the instructions. The first holding current is greater than the second holding current, and the second holding current is greater than the rated current of the stepper motor; the first preset time, the second preset time, the third preset time, and the fourth preset time are preset fixed times.

2. The braking control method based on stepper motor drive according to claim 1, characterized in that, The micro-oscillation calibration includes: controlling the motor to oscillate forward and backward at a preset oscillation angle and preset speed; during the oscillation process, the actual rotation angle signal of the motor is collected in real time by an encoder; the actual rotation angle signal is compared with the preset number of pulses corresponding to the preset oscillation angle to calculate the deviation value; if the actual rotation angle value is less than the preset value, the number of output pulses is increased; if the actual rotation angle value is greater than the preset value, the number of output pulses is decreased; after the oscillation cycle ends, the motor is controlled to return to the initial zero position.

3. The braking control method based on stepper motor drive according to claim 1, characterized in that, The specific method for determining whether the stepper motor has reached a stable state is as follows: real-time monitoring of the motor winding current fluctuation value and the change in motor shaft angle; within a continuous preset monitoring period after the given rated current, if the winding current fluctuation value is within the range of rated current value ± preset current deviation, and the change in motor shaft angle detected by the encoder is within the range of preset pulse deviation, then the motor is determined to have reached a stable state; otherwise, the latest encoder count value is used as the initial count value, and the stable state determination is performed again.

4. The braking control method based on stepper motor drive according to claim 1, characterized in that, After the stepper motor reaches a stable state, the following routine handling is also included: after the stepper motor reaches a stable state, the motor current is at the rated value and the brake device is in the open state; when in a state of no communication or no enable, the motor current is kept at the rated value and the brake device is kept in the open state.

5. The braking control method based on stepper motor drive according to claim 1, characterized in that, After the stepper motor reaches a stable state, it also includes general alarm processing: when the detected deviation value is greater than the first preset pulse threshold, the motor is in the enabled state and the actual speed fed back is 0, or the stall duration exceeds the first preset duration, a stall alarm is triggered. When the actual position of the motor deviates from the target position by more than a preset number of revolutions, an over-tolerance alarm is triggered; when a general alarm is triggered, the brake device is first closed and then the motor drive current is cut off; after receiving a program reset operation, the motor drive current is first returned to the rated value and then the brake device is opened.

6. The braking control method based on stepper motor drive according to claim 1, characterized in that, After the stepper motor reaches a stable state, it also includes a critical alarm handling mechanism: when the motor phase current is detected to be less than the second preset current threshold, it is determined to be a motor phase loss alarm; when the motor current is detected to be greater than the third preset current threshold and continues for more than the second preset time, it is determined to be a motor overcurrent alarm; when the power supply voltage is detected to be less than the first preset voltage threshold or greater than the second preset voltage threshold, it is determined to be an undervoltage or overvoltage alarm; when a critical alarm is triggered, the brake device is first controlled to close and then the motor drive current is cut off, and it cannot be reset by the program, so power-off inspection is required.

7. The braking control method based on stepper motor drive according to claim 1, characterized in that, After the stepper motor reaches a stable state, the system also includes emergency power outage handling: real-time monitoring of the power supply voltage; when the voltage drops sharply from the rated value to below the preset power outage voltage threshold and the duration reaches the third preset duration, it is determined to be an abnormal power outage. When a power outage is detected, a brake closing signal is first sent to control the brake device to close, and then the motor drive current is cut off.

8. The braking control method based on stepper motor drive according to claim 1, characterized in that, The first holding current is a first current ratio of the motor's rated current, the second holding current is a second current ratio of the motor's rated current, and the first current ratio is greater than the second current ratio.

9. A brake control system based on stepper motor drive, characterized in that, For performing the method as described in any one of claims 1-8, comprising: A closed-loop stepper motor module with brake, comprising a stepper motor, an electromagnetic brake device, and an incremental encoder; The driver module includes a data processing module, a communication module, a voltage detection module, a brake signal output interface, a motor current output interface, and an encoder signal input interface; The power supply module is connected to the driver module; The host computer module is connected to the driver module through the communication module; The voltage detection module is connected in parallel to the power supply circuit and is connected to the data processing module; the brake signal output interface is connected to the electromagnetic brake device; the motor current output interface is connected to the stepper motor; and the encoder signal input interface is connected to the incremental encoder.

10. A device based on stepper motor drive, characterized in that, It includes the device body, motion execution components, and the brake control system based on stepper motor drive as described in claim 9; The motion execution component is mounted on the device body, and the stepper motor module with brake closed loop is mounted on the device body or the motion execution component. The output shaft of the stepper motor is connected to the motion execution component for driving the device body to run. The electromagnetic brake device is fixed coaxially with the output shaft of the stepper motor, and the incremental encoder is installed at the tail of the stepper motor. The driver module and the power module are fixed inside the device body and are electrically connected to the stepper motor module with brake closed loop. The host computer module is deployed in the control area of ​​the device body and is used to receive braking or control commands from the operator and send them to the data processing module through the communication module.

Images