Research On Subdivision Drive System Of Three Phase Hybrid Step Motor Based On DSP

Based on an overall review of related papers published at home andabroad about the step motor subdivision control theory and technology, thisdissertation designs a fully digital three-phase hybrid step motorsubdivision drive system, which based on the digital signal processorTMS320LF2407A, to avoid the vibration and noise of hybrid step motor atlow frequency.Firstly, this dissertation introduces the structure and the runningprinciple of the three-phase hybrid step motor, and establishes an idealmodel by ignoring some non-linear factors. Then it analyzes the operatingperformance of the hybrid step motor and the necessity of the subdivisioncontrol. Further more, this dissertation analyses how subdivision improvesthe performance of step motor, and illustrates that the sine-wavesubdivision method can make equal stepping angle and torque. Theanalysis above shows that the step motor and the synchronous motor have similar torque characteristics, on condition that the three-phase statorwindings are input sine-wave current being lack of 120 electric angle eachother, which make hybrid step motor rotates evenly.This drive system adopts sine-wave current subdivision and currenttracking PWM technology and the core processor is Texas Instrument'shigh performance DSP TMS320LF2407A. This dissertation introduces thehardware platform designing, software developing and performance testing.Sine-wave current subdivision technology not only overcomes the motor'svibration and noise at low frequency but also reduces the probability ofresonance. Current tracking PWM technology can maintain constant torquewithin wide speed range. This dissertation proposes a new method to keepconstant speed and improve starting performance when the value ofsubdivision is below 80. This method is named automaticdouble-subdivision with constant speed in this dissertation. The motor runstwo steps on receiving a pulse,Experiments indicate this subdivision driver system can reducevibration and noise of hybrid step motor, and can improve startingfrequency.