The Research On Microstepping Drive For Hybrid Step Motor

At 70s the subdivision control of stepping motors was proposed to solve the problems such as resonance, output torque reducing and low accuracy when the stepping motor is running at open-loop. This thesis mainly analyzes the theory of subdivision and realizes the subdivision of the three phase hybrid stepping motors with digital control.Firstly, this thesis study the characteristic the magnetic filed and stator current of stepper between the PMSM and stepping motors, which indicates that they are similar. From the structure and operation principle and in a certain assumption, the stepping motor can consider as a PMSM running at low speed. When subdivision is adopted, the current in the stator is sinusoidal. Reference on the AC variable speed theory, the sinusoidal current in the stator can transform into direct current through rotational coordinate transform. The modulation policy is SVPWM which is widely adopted in AC motors control to reduce current harmonics and noise. Secondly, with the simulation software Matlab/Simulink, the model of the stepping motor is established base on the d-q coordinate. When the different frequency and step angle are set, the responses curves of current in the stator and the position of the rotor are analyzed. The simulation shows that the method is effective. Finally, with the TI DSP TMS320LF2407A as the controller, the subdivision of the stepping motor is realized. Some suggestions are made to make improvements.