Research On Control Technology Of Speed Sensorless Permanent Magnet Synchronous Motor Based On MRAS

Permanent magnet synchronous motor (PMSM) is widely used in various fields of society for so many advantages, such as small size, low noise, high efficiency, high power density and soon. With the rapid development of power electronic technology and modern control theory, the AC motor speed control technology is becoming more and more mature, and especially the direct torque control (DTC) technology has been paid more attention due to the characteristics of simple structure, fast dynamic response, less dependence on motor parameters. However, in the process of speed control, the speed sensor is easy to be influenced by the surrounding environment, which reduces the system reliability and increases the cost of the system. Therefore, the research on speed control of speed sensorless is a hot research in recent years.In this paper, the permanent magnet synchronous motor is used as the controlled object firstly, and the mathematical model of the permanent magnet synchronous motor is analyzed. In view of the fact that the traditional direct torque control flux and torque ripple, and the switching frequency is not constant, the space voltage vector modulation (SVM) technology is applied to the direct torque control. The simulation of the system model is built in Matlab-Simulink environment.Then, the model reference adaptive system (MRAS) is used to estimate the speed of the motor. Taking the permanent magnet synchronous motor mathematical model as the reference model, the reference model is built with the adjustable parameters of the motor rotational speed, and the suitable adaptive rate is constructed to meet the Popov’s theorem. Applying it in the system and the speed identification model is built and simulated in Matlab-Simulink environment.Finally, using TMS320F28335 as the main control chip to build control circuit, driving circuit, sampling circuit, filter circuit, isolation circuit, and establishing an experiment platform of the system. A permanent magnet synchronous motor with a rated power of 1.8kW is selected as the controlled device. Software program is written under the environment of CCS3.3, to achieve the control scheme of speed sensorless permanent magnet synchronous motor based on MRAS.