Research Of Fuzzy Adaptative Vector Control Of Asynchronous Motor Based On MRAS

Vector control system of induction motor is based on vector coordinate transformation theory and energy conversion. The basic idea of vector control is as follows: Taking producing the same revolving magnetomotive force for criterion, transform the stator AC currents of asynchronous motor in static three-phase coordinate to DC currents in the synchronous revolving coordinate using equivalent coordinate conversion, and control DC currents separately by which we can realize decoupling control of the flux and the torque and therefore, achieve the effect of DC motor control.The paper presents a dual closed-loop vector control system based on DSP for asynchronous motor which is a multi-variables, nonlinear, strong coupling and time-varying system and is difficult to determine precise mathematical model because of changes in motor parameters and load fluctuations in factors. Speed controller uses a parameters self-adjusting fuzzy controller and flux observer uses an improved combining methods of voltage model and current model. According to the theory of speed sensor-less vector control system, it proposes a novel scheme of identifying the rotor speed based on MRAS(Model Reference Adaptive System), which could achieve a large range of speed identification, while ensuring the fast dynamic response of system.Finally, it's briefly designed the hardware and software of system, with TMS320LF2417 DSP of TI Company as the core, the hardware includes the main circuit, control circuit and auxiliary circuit. Simulation results illustrate that the system obtains satisfactory results in the dynamic response, anti-interference ability and robustness.