1, structure:

the motor rotor is evenly distributed with many small teeth, the stator teeth have three excitation winding resistance, the geometric axis in turn respectively staggered with the rotor tooth axis. 0, 1/3て, 2/3て, (the distance between the axes of the two adjacent rotor teeth for the tooth distance to て), that is, A and tooth 1 flush, B and tooth 2 to the right staggered 1/3て, C and tooth 3 to the right staggered 2/3て, A 'and tooth 5 flush, (A 'is A, tooth 5 is tooth 1)

2, rotation:

such as A phase energized, B, C phase is not energized, due to the magnetic field, tooth 1 and A alignment, (rotor is not subject to any force below are the same). If the B phase is energized, A, C phase is not energized, tooth 2 should be aligned with B. At this time, the rotor is shifted to the right by 1/3て, then tooth 3 and C offset by 1/3て, tooth 4 and A offset (て-1/3て) = 2/3て. If phase C is energized and phase A and B are not energized, tooth 3 should be aligned with C. At this time, the rotor is shifted to the right by 1/3て, and tooth 4 is aligned with A with an offset of 1/3て. If phase A is energized, phase B, C is not energized, tooth 4 is aligned with A, and the rotor is shifted over 1/3て to the right This way after A, B, C, A are energized state, tooth 4 (i.e. tooth 1 before a tooth) is shifted to phase A, and the motor rotor is shifted over a tooth pitch to the right, if it is constantly energized by A, B, C, A......, the motor is energized every step (every pulse) 1/3て,rotate to the right.If you press A, C, B, A ...... to energize, the motor reverses. It can be seen that the position and speed of the motor are in one-to-one correspondence by the number of conductivity (number of pulses) and frequency. And the direction is determined by the conductive sequence. However, for considerations of torque, smoothness, noise and angle reduction. The conductive state of A-AB-B-BC-C-CA-A is often used, so that the original 1/3 て per step is changed to 1/6 て. Even through the two-phase current different combinations, so that its 1/3 て into 1/12 て, 1/24 て, which is the basic theoretical basis of the motor subdivision drive. It is not difficult to introduce: the motor stator has m-phase excitation winding, whose axes are offset from the rotor tooth axis by 1/m,2/m ......(m-1)/m,1. And conductive according to a certain phase sequence motor can be controlled forward and reverse - this is the physical condition of rotation. As long as this condition is met we can theoretically manufacture any phase of the stepper motor, for cost and other considerations, the market is generally two, three, four, five-phase for more.

3, torque:

once the motor is energized, the magnetic field will be generated between the stator and rotor (magnetic flux Ф) when the rotor and stator staggered at an angle to generate force F and (dФ / dθ) proportional to S its magnetic flux Ф = Br * S Br is the magnetic density, S is the permeable area F and L * D * Br proportional to L is the effective length of the core, D is the diameter of the rotor Br = N-I / R N-I is the number of turns of excitation winding amp (current times the number of turns) R is the magnetoresistance. Torque = Force * Radius Torque is proportional to effective motor volume * number of turns * magnetic density (only linear state is considered) Therefore, the larger the effective motor volume, the larger the number of turns of excitation, the smaller the air gap between stator and rotor, the larger the motor torque, and vice versa.