Study Of AC Motor FOC Based On DSP

Vector control (VC) is based on motor unification principle, energy conversion and vector coordinate transformation theory. By transforming coordinate,the stator current is decomposing two DC parts which orientated as the rotator magnetic field and controlled respectively. So magnetic flux and torque are decoupled. It controls the asynchronous motor as a synchronous way. This paper does some research works of the vector control technology based on rotator field oriented and then designs the whole system with DSP.The vector control theory and its decoupling are introduced on the foundation of the mathematical model of asynchronous motor. The variables in 3-phase static coordinates are converted into the variables in rotating coordinates and the components between torque and magnetic field of stator winding current are decoupled which uses the rotor-field-oriented technology. Thus, the speed regulating performance of the asynchronous motor is improved highly. The structure diagram of vector control system which combines the current model of motor is given and provides the theoretical basis for the design of vector control system platform.The speed PI regulator and the current PI regulator are designed and the PI controller parameter tuning method is analyzed. a novel method for tuning PID parameters is given. The tuning problem is solved by maximizing the phase margin of the Nyquist curve of the open loop transfer function.AC variable frequency speed-adjusting system of asynchronous motor with speed-current double closed-loop is researched and software and hardware systems are designed in this paper. This system adopts SVPWM (Space Voltage Pulse Width Modulation) control technology and FOC (Field Oriented Control) control algorithm based on TMS320LF240DSP which is special chip of TI for motor control. The modularization design is adopted in software so that it can be amended and replanted easily. The SVPWM vector control strategy is carried out. At last, the hardware and software is debugged in this paper.