Intelligent control system applied to stepping motor driving

Abstract

The invention relates to the field of motor control, in particular to an intelligent control system applied to stepping motor driving, which does not depend on a sensor, can automatically adjust current or rotating speed in real time according to the change of an external load, and avoids overload, stalling and the like, and comprises a current loop adjusting module, a current loop control module and a current loop control module, according to the error between the measured output current of the motor and the target current, the voltage duty ratio is adjusted after feedback, and the current of the motor is controlled; the load torque calculation module is used for calculating the load torque according to the duty ratio and the current output by the current loop adjustment module; the hysteresis regulation module is used for carrying out current self-adaption or speed self-adaption regulation and outputting a corresponding current instruction or a corresponding speed instruction to the current loop regulation module; and the driving circuit generates a corresponding PWM driving signal to drive the H bridge and acts on the motor to generate current.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to an intelligent control system applied to stepper motor drive. Background Art

[0002] Stepper motors offer advantages such as simple structure and high control precision. Essentially, they convert electrical pulse signals into corresponding angular or linear displacements, hence the name pulse motor. They are widely used in various power control systems, particularly in industrial automation, household consumption, healthcare, and other fields requiring position control. Due to the wide variety of applications, the demand for various feedback systems for stepper motors is extensive. During use, stepper motors are prone to stalling and have low static torque. Control systems often require feedback units to detect stall conditions to ensure accuracy and reliability. Furthermore, overloading a stepper motor can lead to overheating, degrading winding insulation, shortening the motor's lifespan, and, in severe cases, burning out. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides an intelligent control system for stepper motor drive, which does not rely on sensors and can automatically adjust the current or speed in real time according to changes in external load to avoid overload, stall and other situations.

[0004] The technical solution is as follows: an intelligent control system for stepper motor drive, characterized in that it includes:

[0005] The current loop regulation module adjusts the voltage duty cycle based on the error between the measured motor output current and the target current, thereby controlling the motor current.

[0006] The load torque calculation module calculates the load torque according to the duty cycle and current output by the current loop regulation module;

[0007] The hysteresis loop regulation module performs current adaptive or speed adaptive regulation and outputs the corresponding current command or speed command to the current loop regulation module;

[0008] The driving circuit generates a corresponding PWM driving signal to drive the H-bridge, and acts on the motor to generate current.

[0009] It is further characterized in that the load torque calculation formula is Where K1 is a constant under given working conditions, τ is the load torque, ω is the motor speed, IAMP is the current amplitude, Q T is the load torque applied to the stepper motor;

[0010] Current adaptive regulation: Adjust the motor current to adjust Q T Limited to QT _UL and Q T Within the hysteresis range defined by the _LL parameter, Q T _UL and Q T _LL are the preset upper and lower thresholds respectively;

[0011] Speed adaptive adjustment: Adjust the motor speed to adjust Q T Limited to Q T _UL and Q T Within the hysteresis range defined by the _LL parameter, Q T _UL and Q T _LL are the preset upper and lower thresholds respectively.

[0012] After adopting the present invention, there is no need to design position or speed sensors, etc., which is low-cost and simpler. By utilizing load detection and adaptive control, the load size and stall situation can be detected in time, and the torque or speed can be adjusted in real time according to the load size, avoiding loss of step and reducing energy loss at the same time, so that the motor has the advantages of significant energy saving, high efficiency and long life. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the system of the present invention;

[0014] Figure 2 Schematic diagram of current adaptive regulation;

[0015] Figure 3 Schematic diagram of speed adaptive adjustment. DETAILED DESCRIPTION

[0016] In a stepper motor system, the total power provided by the power supply is used to meet the torque requirements of the load, resulting in constant losses caused by the motor winding resistance and the driver on-resistance. When the load torque increases, the power provided by the power supply also increases. The system obtains information about the load torque by monitoring the power provided by the power supply. The constant loss is given by Q R The parameter indicates that for any given motor, Q R Proportional to the coil current, i.e. Q R =K0·I, where K0 is a constant and I is the current amplitude. R The linear relationship between the current and the motor current is that the system can give any two currents at any load. By monitoring the power provided by the power supply, Q can be learned. R value, and then use this relationship to interpolate the corresponding constant loss at any other current. R Value Q T The parameter represents the power component supporting the load torque, i.e. Where K1 is a constant under given working conditions, τ is the load torque, ω is the motor speed, I AMPis the current amplitude. Q T Can be used to represent the load torque applied to a stepper motor.

[0017] When implementing stall detection, first give the current and speed required by the application, and then manually increase the load from no load. T It will also increase until the motor stalls and record the minimum Q T_MIN and Q when out of step T_MAX value, and as Q T_MAX As the stall threshold; in subsequent normal operation, as long as it reaches or approaches the threshold, it is considered that the motor is about to stall. At this time, feedback can be given to the host computer or control system to perform corresponding operations or shut down the motor drive, which can protect the motor and avoid the occurrence of phenomena such as loss of step, mechanical wear, noise and mechanical failure.

[0018] See Figure 1 As shown, an intelligent control system for stepper motor drive includes:

[0019] The current loop adjustment module 303 adjusts the voltage duty cycle based on the error between the measured motor output current and the target current and controls the motor current.

[0020] The load torque calculation module 301 calculates the load torque according to the duty cycle and current output by the current loop regulation module;

[0021] The hysteresis loop adjustment module 302 performs current adaptive or speed adaptive adjustment and outputs the corresponding current command or speed command to the current loop adjustment module;

[0022] The driving circuit 304 generates sine and cosine voltage modulation waves with a phase difference of 90 degrees. The two-phase modulation waves are compared with the triangular carrier respectively to generate corresponding PWM driving signals to drive the H bridge and act on the motor M to generate current.

[0023] When current adaptation is implemented, the motor current can be adjusted by T limited by the user-programmable Q T _UL and Q T _LL parameter defines the hysteresis range, such as Figure 2 If the external load increases (from T1 to T2), Q T Will exceed Q T _UL threshold, in order to limit the Q T , the system will increase the current (I3 to I4) to Q T When the load torque demand decreases (from T2 to T1) and Q T Lower than Q T _LL, the system will reduce this current (I4 to I3), making Q TIt returns to the hysteresis range again.

[0024] When speed adaptation is implemented, the motor speed can be adjusted by T limited by the user-programmable Q T _UL and Q T _LL parameter defines the hysteresis range, such as Figure 3 If the external load increases (from T1 to T2), Q T Will exceed Q T _UL threshold, in order to limit the Q T , the system will reduce the speed (ω3 to ω4) to make Q T When the load torque demand decreases (from T2 to T1) and Q T Lower than Q T _LL, the system will increase the speed (ω4 to ω3), so that Q T Back to the hysteresis range again.

[0025] The system of the present invention is composed of a current inner loop control and a power adaptive outer loop. The internal operation logic is carried out as described above. With the change of external load, the torque and speed output are intelligently controlled. The bandwidth of the control loop depends on the bandwidth of the current loop. As can be seen from the above, Q T Higher _UL values save more power at peak loads, but the motor may stall in the event of fast load transients. Lower Q T A higher _LL value will reduce energy savings at peak loads, but will also reduce the likelihood of the motor stalling and losing steps.

Claims

1. An intelligent control system for stepper motor drive, characterized in that: It includes: The current loop regulation module adjusts the voltage duty cycle based on the error between the measured motor output current and the target current, thereby controlling the motor current. The load torque calculation module calculates the load torque according to the duty cycle and current output by the current loop regulation module; The hysteresis loop regulation module performs current adaptive or speed adaptive regulation and outputs the corresponding current command or speed command to the current loop regulation module; The driving circuit generates a corresponding PWM driving signal to drive the H-bridge, and acts on the motor to generate current. It is further characterized in that the load torque calculation formula is Where K1 is a constant under given working conditions, τ is the load torque, ω is the motor speed, IAMP is the current amplitude, Q T is the load torque applied to the stepper motor; Current adaptive regulation: Adjust the motor current to adjust Q T Limited to Q T _UL and Q T Within the hysteresis range defined by the _LL parameter, Q T _UL and Q T _LL are the preset upper and lower thresholds respectively; Speed adaptive adjustment: Adjust the motor speed to adjust Q T Limited to Q T _UL and Q T Within the hysteresis range defined by the _LL parameter, Q T _UL and Q T _LL are the preset upper and lower thresholds respectively.

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