How does the stepper motor work?

Stepper motor is a kind of control motor that converts electrical pulse signal into mechanical angular displacement. The so-called electrical pulse is similar to a pulse,and when the pulse is felt,it is similar to the high level of the pulse, and when it is not jumped, it is low, which is the electrical pulse signal. Angular displacement is measured in radians.

Stepper motor can be divided into reactive, permanent magnet, hybrid. Each has its own advantages, according to the actual demand selection, reaction step Angle is small, high precision; The torque of the permanent magnet is large. The hybrid type has the characteristics of high precision and large torque, but the cost is high. The following takes the reactive type as an example to explain the structure and working principle of the stepper motor. 

Stepper motor is mainly composed of two parts:
Stator and rotor. Stator and rotor are familiar after learning DC motors. However, the stepper motor takes the three-phase as an example, and its stator and rotor have six and four magnetic poles respectively. In the figure above, A and A form a phase; B is in phase with B; C is in phase with C. Therefore, this stepper motor is a three-phase stepper motor.

When the stepper motor receives an electrical pulse signal, it will rotate a fixed Angle accordingly, and this fixed Angle is an important parameter of the stepper motor, the step Angle. In detail, when the stepper motor receives an electrical pulse signal, A is connected to electricity, and the magnetic flux in the direction of A forms a closed loop through the rotor. If the axis direction of the rotor and the magnetic field is originally a certain Angle, the rotor is magnetized under the action of the magnetic field, attracting the rotor, so that the teeth of the rotor and the stator are aligned to stop rotating. That is, A is connected to make the rotor 1, 3 teeth and AA' align; In the next pulse signal, B is electrically connected to align the rotor teeth 2 and 4 with BB; After the third pulse signal comes, C communicates electricity to align the rotor teeth 3 and 1 with CC'. This driving mode is a three-phase three-beat driving mode.

Therefore, the stepper motor is rotated by the number of pulses, and how many turns are needed to give the corresponding number of pulses. Therefore, the stepper motor can achieve the purpose of accurate positioning; At the same time, the speed and acceleration of the motor rotation can be controlled by controlling the pulse frequency, that is, how long to control a pulse, so as to achieve the purpose of speed regulation. With each input electrical pulse, the motor rotates at an Angle further ahead. The angular displacement of its output is proportional to the number of input pulses, and the speed is proportional to the pulse frequency. Change the order of winding power, control the motor positive and negative rotation. That is, if the power order of phase A, B, and C is positive, then the motor will be reversed in the order of phase C, B, and A. Therefore, the number of pulses, frequency and the electrification sequence of each phase winding of the motor can be controlled to control the rotation of the stepper motor.

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