What is the structure, type, and working principle of stepper motor?

In the "Pengpeng Science and Art" ** "Reluctance Motor" column, there is an animation to demonstrate the working principle of the stepper motor, which is very intuitive and can be understood at a glance.

The stator and rotor cores of progressive motors are made of silicon steel sheets. There are six magnetic poles on the stator, and each of the two opposing poles is wound with the same phase winding, and the three-phase winding is connected into a star shape as the control winding. There are no windings on the rotor core, only four teeth, and the tooth width is equal to the width of the stator pole shoe.

Because of the wide application of stepper motors, the control of stepper motors is also more and more studied, if the stepper pulse changes too fast when starting or accelerating, the rotor cannot follow the change of the electrical signal due to inertia, resulting in stalled or out-of-step due to the same reason when stopping or decelerating. In order to prevent stalling, out-of-step and overstepping, and increase the working frequency, it is necessary to control the speed of the stepper motor.

The stator and rotor cores of the stepper motor are made of silicon steel sheets.

There are six magnetic poles on the stator, and each of the two opposing poles is wound with the same phase winding, and the three-phase winding is connected into a star shape as the control winding. There are no windings on the rotor core, only four teeth, and the tooth width is equal to the width of the stator pole shoe.

A stepper motor is an open-loop control element that converts an electrical pulse signal into angular or linear displacement.

Type of stepper motor.

There are three main types of structure-based stepper motors:

Variable reluctance stepper motors: they have an iron-core rotor that is attracted by the stator pole and provides motion through the minimum magnetoresistance between the stator and the rotor.

Permanent magnet stepper motors: They have permanent magnet rotors that are repelled or attracted to the stator depending on the applied pulse.

Hybrid synchronous stepper motors: They are a combination of variable reluctance and permanent magnet stepper motors.

In addition to this, stepper motors can also be classified into unipolar and bipolar depending on the type of stator winding.

Let's understand the structure and working principle of stepper motor.

Working principle: Usually the rotor of the motor is a permanent magnet, and when the current flows through the stator winding, the stator winding generates a vector magnetic field. This magnetic field causes the rotor to rotate by an angle so that the direction of the pair of magnetic fields of the rotor coincides with the direction of the magnetic field of the stator.

When the vector magnetic field of the stator rotates by an angle. The rotor also rotates at an angle with this magnetic field.

With each input electrical impulse, the motor rotates an angle to take a step forward. The angular displacement of its output is proportional to the number of pulses input, and the rotational speed is proportional to the pulse frequency. Change the order in which the windings are energized, and the motor will be reversed.

Therefore, the rotation of the stepper motor can be controlled by controlling the number of pulses, the frequency and the energizing sequence of each phase winding of the motor.

Most of the stepper motors used in computerized embroidery machines are three-phase hybrid. The stepper motor and the subdivision drive can greatly improve the stepping. The running quality of the feed motor reduces the torque fluctuation, suppresses the oscillation, reduces the noise, and improves the stepping resolution.

1. Stepper motors are mainly used in some fields with positioning requirements. Off, such as: line header drag, planting machine (wool hole positioning), packaging machine (fixed length), basically involves positioning.

You can use it for any occasion. It is widely used in ATM machines, inkjet printers and engraving machines. Procurement of products** machines, spraying equipment, medical instruments and equipment, computer peripherals and mass storage equipment, precision instruments, industrial control systems, office automation.

Chemical, robotics and other fields, especially suitable for stable operation and low noise occasions. The sound is loud, the response is fast, the life is long, and the output torque is large. 3. Stepper motors in computerized embroidery machines and other textile machinery and equipment.

With a wide range of applications, this stepper motor is characterized by keeping the torque constant. High, frequent start-up, fast response, low operating noise, stable operation, good control performance, and low overall cost. Precautions in stepper motor applications This machine is used in low-temperature occasions and the speed per minute does not exceed.

1. According to the external control pulse and direction signal, the stepper motor driver controls the winding of the stepper motor to be energized in a certain timing forward or reverse direction through its internal logic circuit, so that the motor is forward and reverse rotated, or locked.

2. Take the degree two-phase stepper motor as an example: when the two-phase windings are energized and excited, the output shaft of the motor will be stationary and lock the position. The maximum torque that keeps the motor locked at the rated current is the holding torque.

If the current in one of the windings of one of the phases changes direction, the motor will rotate one step (degree) in a given direction. Similarly, if the current of another winding changes direction, the motor will rotate one step (degrees) in the opposite direction to the former. When the current through the coil winding changes to excitation sequentially, the motor will realize continuous rotation and step along the given direction, and the running accuracy is very high.

For a two-phase stepper motor, it takes 200 steps to rotate one cycle.

3. There are two winding forms for two-phase stepper motors: bipolar and unipolar. There is only one winding coil on the bipolar motor on each punch phase, and the current should be changed to excitation in turn in the same coil when the motor rotates continuously, and eight electronic switches are required to switch sequentially in the design of the driving circuit.

4. There are two winding coils with opposite polarity on each phase of the unipolar motor, and when the motor rotates continuously, only the two winding coils on the same phase are energized and excited. Only four electronic switches are required for the drive circuit design. In bipolar drive mode, the output torque of the motor in bipolar drive mode is about 40% higher than in unipolar drive mode because the Naqi winding coil of each phase is 100% excited.