Working principle of stepper motor

When current flows through the stator winding, the stator winding generates a vector magnetic field. The magnetic field will drive the rotor to rotate by an angle, so that the pair of magnetic field directions of the rotor are consistent with the magnetic field directions of the stator. When the vector magnetic field of the stator rotates by an angle. The rotor also rotates an angle with the magnetic field. Each time an electric pulse is input, the motor rotates one angle to move forward. The angular displacement that it outputs is proportional to the number of input pulses, and the speed is proportional to the pulse frequency. Change the sequence of energizing the windings and the motor will reverse. Therefore, the number of pulses, frequency and the energization sequence of each phase winding of the motor can be used to control the rotation of the stepper motor.

All types of motors that are usually seen have iron cores and winding coils inside. Windings have resistance, energization will produce losses. The loss is proportional to the square of the resistance and the current. This is what we often call copper loss. If the current is not a standard DC or sine wave, harmonic losses will also occur; iron cores have hysteresis The eddy current effect also produces loss in an alternating magnetic field, and its magnitude is related to the material, current, frequency, and voltage, which is called iron loss.

Copper loss and iron loss will show up in the form of heat, which affects the efficiency of the motor. Stepper motors generally pursue positioning accuracy and torque output, with relatively low efficiency, relatively large currents, and high harmonic components. The frequency of current alternation also changes with the speed. Therefore, stepping motors generally have heat generation, and the situation is more common. The AC motor is serious.