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Stepper Motor

Definition - What does Stepper Motor mean?

A stepper motor is a type of DC motor that works in discrete steps. It is a synchronous brushless motor where a full rotation is divided into a number of steps. The two main components of a stepper motor are the rotor and the stator. The rotor is the rotating shaft and the stator consists of electromagnets that form the stationary part of the motor. When a discrete DC voltage is applied, the stepper motor rotates in a particular angle called the step angle; thus a stepper motor is manufactured with steps per revolution of 12, 24, 72, 144, 180 and 200, with a corresponding step angle of 30,15, 5, 2.5, 2 and 1.8. It can be operated with or without a feedback control.

Techopedia explains Stepper Motor

A stepper motor is a particular type of DC motor that does not rotate continuously. Instead, a full rotation is divided into a number of equal steps. A stepper motor consists of phases, which are multiple coils that are organized into groups. By applying the energy from the input voltage to each phase in a sequence, the stepper motor rotates by taking one step at a time. Thus a stepper motor converts electrical energy or an input digital pulse into mechanical shaft rotation.

A stepper motor works under the principle of electromagnetism. A permanent magnet or soft iron is used as the rotor and is surrounded by electromagnetic stators. The poles of the rotor and stator may be teethed. When voltage is applied at the terminals, the rotor aligns itself with the stator or moves to have a minimum gap with the stator due to the magnetic effect. The stators are energized in a sequence and the rotor moves accordingly, giving a full rotation that is divided into a discrete number of steps with a particular step angle.

The four major types of stepper motor are as follows:

  • Permanent magnet stepper
  • Hybrid synchronous stepper
  • Variable reluctance stepper
  • Lavet-type stepping motor

A stepper motor is used in devices that need precise positioning and speed control. Because it moves in precise repeatable steps, the stepper motor is used in devices like 3D printers, camera platforms, plotters, scanners, etc. And because it has maximum torque at low speeds, the stepper motor is also used in devices that require a low speed.

A stepper motor has low efficiency as its current consumption is independent of the load, and it consumes more energy than other DC motors. Its torque is also reduced when used in high-speed applications. Although a stepper motor can operate in open-loop control systems, it lacks an integrated feedback system for positioning and control.

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