Dsp-based Frequency Control System

Field Oriented Control (FOC) is based on motor unification principle, energy conversion and vector coordinate transformation theory. It has many advantages such as novelty, practicability and advancement. 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.Using digital signal processor(DSP), TMS320F240, which is special for motor control ,we develop one frequency conversion adjustable-speed system witch based on FOC principle. The mam circuit of the inverter, the detect circuit of current and motor speed ,intelligent power module(IPM) and DSP are all presented particularly hi this paper. At the same time, new Pulse Width Modulation(PWM) named Space Vector Pulse Width Modulation (SVPWM) method is used to control the asynchronous motor.At the end of the paper, some new control methods and improvement are discussed.