I. INTRODUCTION
Stepper motor, as a special type of motor, occupies an important position in modern industrial control system. Its unique control method and wide range of applications make stepper motor a key component in the field of automation control. In this paper, we will start from the control principle of stepper motor, in-depth discussion of its working principle, characteristics and application examples in different fields, in order to provide readers with a comprehensive and in-depth understanding.
II. The control principle of stepper motor
Stepper motor is a kind of electrical pulse signal is converted into an angular displacement or line displacement of the motor. Its control principle mainly includes the input of pulse signals and the control of the drive current in two aspects.
Pulse signal input
The rotation of the stepper motor is driven by inputting pulse signals. The pulse signals can be generated by a switching circuit or issued by a computer or other control system. The frequency of the pulse signal determines the speed at which the stepper motor rotates, while the number of pulse signals determines the angle at which the stepper motor rotates. When a pulse signal is input to one of the stator coils of a stepper motor, the coil generates a magnetic field. According to the law of electromagnetic induction, this magnetic field will produce a torque on the rotor, causing it to rotate by a certain angle. When the pulse signal is no longer input, the magnetic field also disappears and the rotor stops rotating. If the pulse signal is continuously input, then the stepper motor will keep rotating.
Control of drive current
The coil of a stepper motor is usually wrapped in an insulating material to prevent current loss. The drive current is controlled by applying a suitable voltage to the stator coil of the stepper motor. According to Ohm's law, the ratio of current to voltage is equal to the resistance of the coil. By varying the voltage, the current in the coil can be controlled, which in turn controls the rotation speed and torque of the stepper motor. In practice, a driver is often used to control the drive current of a stepper motor. The driver receives an external pulse signal and transmits the current signal to the stator coil via a current amplifier. In addition, by changing the direction of the current in the stator coil, the direction of rotation of the stepper motor can be changed.
III. Characteristics of Stepper Motors
Stepper motor has the following significant features:
Precise control: Stepping motor can realize precise angular displacement or line displacement control by controlling the frequency and number of pulse signals.
High-speed response: stepper motor responds quickly to the pulse signal and can complete the action quickly.
Good stability: stepper motor is stable during operation and is not easily affected by external interference.
High reliability: the structure of stepper motor is simple, fewer parts, so it has high reliability.
IV. Application examples of stepper motor
Stepping motor is widely used in various fields because of its unique control method and excellent performance characteristics. The following are several typical application examples:
Soft disk drive
In the soft disk memory, the stepper motor is used to drive the spindle to rotate the disk in the disk sleeve. At the same time, the stepper motor drives the magnetic head carriage through the transmission mechanism, which transforms the step angle into the displacement of the magnetic head to read and write the disk data. For each step of the stepper motor, the magnetic head moves one track.
Needle Printer Drive
In a pinprinter, a stepper motor is used to drive the print head in a lateral motion. The stepping speed of the print head is determined by the number of drive pulses in a unit of time, and changing the stepping speed changes the print pitch. This application takes full advantage of the precise control and high speed response of the stepper motor.
Computerized Embroidery Machine Driver
Computerized embroidery machines are developed on the basis of computerized sewing machines. In computerized embroidery machines, stepper motors are used to drive the table for planar motion, while monitoring the rotation of the spindle motor that drives the embroidery needle for upward and downward motion. By controlling the trajectory and speed of the stepper motor, various complex embroidery patterns can be realized.
Computerized Plotter
Stepping motors are widely used in computerized plotters because they can accurately convert pulses into angular or linear displacements. By controlling the trajectory and speed of the stepper motor, the plotter can draw the desired trajectory curves on a flat surface within the precise allowable range.
Machining equipment
Stepper motors are also widely used in machining equipment as actuators to drive mechanical moving parts. When open-loop control is used, the system structure is simple and has a certain degree of motion control accuracy.
V. Conclusion
In summary, stepper motor plays an important role in modern industrial control system with its precise control, high speed response, good stability and high reliability. Through the in-depth understanding of the stepper motor control principle and the analysis of application examples, we can better master the use of stepper motors and application scenarios, and make a greater contribution to the development of industrial automation control field.