What is the working principle of a stepper motor?

Stepper motor, an executive element, is one of the key products of mechatronics and is widely used in a variety of automated control systems. As microelectronics and computer technology develop rapidly, there’s an increasing demand for stepper motors in various fields. Everyone in the electricity industry should manage to have a more in-depth understanding of its structure, working principles and applications. Here high quality stepper motor factory Leili Motor introduces a stepper motor in a comprehensive manner in terms of three aspects.

What is a stepper motor?

A stepper motor, also known as step motor or stepping motor, is a kind of electromechanical device that directly converts electrical pulses into mechanical movement. The controlling of the sequence, frequency and number of electrical pulses applied to the motor coils can help control its steering, speed and rotation angle. A best step motor and its accompanying driver constitute a simply controlled and low-cost open-loop control system, which can achieve accurate position and speed control, requiring no closed-loop feedback control system with position sensing. A stepper motor mainly consists of front end cover, bearing, center shaft, rotor core, magnet, winding insulation, stator core, curved washer, rear end cover, and screw.

What is the working principle of a stepper motor?

The stepper motor driver controls the winding to be energized in certain timing sequence in forward or reverse direction according to external control pulses and direction signals through its internal logic circuit, making the motor rotate forward/reverse or lock.

For a 1.8 degree two-phase stepper motor, when the windings of twp phases are energized and excited, the motor output shaft will be stationary and locked in position. The maximum torque that keeps the motor locked at the rated current is the holding torque. If the current of the winding in one of the phases changes its direction, the motor will rotate by one-quarter pitch (1.8°) in a given direction, according to study from step motor suppliers; if the current of the winding in another phase is redirected, the motor will rotate by one-quarter pitch (1.8°) in the opposite direction. When the currents passing through the coil winding are sequentially redirected to excitation, the motor will continuously rotate accurately in the given direction.

Two-phase best step motors are available in two basic winding types: bipolar and unipolar. A bipolar motor has a single winding coil per phase, and rotates continuously with the current in the same coil to be excited in sequence, so the high quality stepper motor factory should design the drive circuit with eight electronic switches for sequential switching. Unipolar motors have two winding coils of opposite polarity on each phase, and rotate continuously by alternately energizing the two winding coils on the same phase. Only four electronic switches are needed for the design of the drive circuit. The output torque of the motor is increased by about 40% in the bipolar drive mode compared to the unipolar drive mode because the winding coils of each phase are 100% excited.

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