Research On Speed Sensorless And Twelve Voltages Direct Torque Control System

Direct torque control (DTC) system for asynchronous machine has got wide attention with the advantages such as its new thoughts, simple control scheme and excellent performance. In this thesis the author made a study of asynchronous motor model and the basic principle of the DTC system, designed a simulation system of DTC and analyzed the characteristics of the DTC system and the existing problems detailed. This thesis made a development of the DTC system in using the twelve-voltage inverter solved the problem of the large torque ripple and current ripple at operation status efficiently. This thesis obtains the scheme of MRAS to estimate the asynchronous'speed, it can carry out the technique of the sensorless. The author designed a speed regulator based on sliding-mode control theory, which make the system has strong robustness. Simulation results show the method is effective.