Study On Speed Sensor-less Variable Frequency Speed Regulation System

The application of speed sensor-less variable frequency speed regulation thecnique in electric drive system can reduce cost , enhance systemic reliability, benefit to the development toward high-speed and miniaturization trend of AC motor, furthermore, save plenty of electric energy and bring immence economy benefit.The core issue of speed sensor-less technique is accurate identification of rotor speed guaranteeing stability of the system. Compared to other methods of rotor speed identification, model reference adaptive control has advantages such as simple structure, easy realization and precise identification, as a result, present methods based on MRAC are often adopted in rotor speed identification link of speed sensor-less variable frequency speed regulation system.Firstly, proceeding from dynamic model of asynchronous motor here, basic theory and coordinate transformation of vector control is introduced, state equations of asynchronous motor in two-phase static coordinate are deduced, and vector control system of induction motor based on rotor flux orientation is built. Secondly, theory and methods of voltage SVPWM control technique is analyzed and its realization algorithm is deduced in detail. Then MRAC identification strategy of rotor speed based on rotor flux linkage is introduced after analysing basic idea of MRAC parameter identification. Thirdly, based on the adoption of vector control and voltage-type space vector pulse width modulation control, speed sensor-less variable frequency speed regulation system is built using MRAC strategy to identify rotor speed of asynchronous motor on line. Besides, system model is built and simulation is carried out in MATLAB7.1/Simulink environment. Through analysis of the simulation waves, the validity and feasibility of the system model is verified. Finally, the software and hardware of the system is designed and speed sensor-less variable frequency speed regulation system with MRAC identification strategy of rotor speed based on rotor flux linkage is realized in experiment.