stepper motor Stator winding
Stepping motor subdivision control is essentially through the stepper motor stator winding current control, so that the stepper motor within the synthetic magnetic field changes according to a certain requirements, in order to achieve stepper motor step angle subdivision The In general, the amplitude of the synthetic magnetic field vector determines the magnitude of the motor rotation torque, and the angle between the adjacent two synthetic magnetic field vectors determines the magnitude of the step angle. In the motor to produce close to the uniform circular rotating magnetic field, the phase of the composite magnetic field vector, which requires the phase in the phase through the sinusoidal current.
Hybrid stepper motor is the combination of permanent magnet and the advantages of the reaction. Three-phase hybrid stepper motor works very much like an AC permanent magnet synchronous stepper motor. The permanent magnet magnet used in the rotor is also a rare earth permanent magnet material with high magnetic density, so the effect of the induced current on the rotor on the rotor magnetic field is negligible. In the structure, it is equivalent to a multi-pole logarithmic alternating current permanent magnet synchronous motor. Since the input is a three-phase sinusoidal current, the resulting magnetic field is circularly distributed, and the torque characteristics of the three-phase hybrid stepping motor can be analyzed by the structural model of the permanent magnet synchronous motor.
A. Motor stator three-phase winding completely symmetrical;
B. Magnetic saturation, eddy current and core loss are ignored;
C. Excitation current without dynamic response process;
The above analysis shows that for a three-phase permanent magnet synchronous motor, when the three-phase winding input phase difference of 120 ° sinusoidal current, due to the internal circular rotating magnetic field, the motor output torque is constant. Therefore, the AC stepping control principle is applied to the three-phase hybrid stepping motor drive system, the input 220V AC, after rectification into DC, and then through the pulse width modulation technology into a three-step ladder-type sine wave current, they According to the fixed timing, respectively, through the three-way winding, by changing the driver output sine current frequency to change the motor speed, the output of the ladder to determine the angle of each step, when the angle is smaller, the more the number of steps. Of course, when the stepper motor rotates, the inductance of each phase winding of the motor will form a reverse electromotive force, the higher the frequency, the greater the reverse electromotive force. In its role, the motor with the frequency (or speed) increases and phase current decreases, resulting in decreased torque.