Research And Implementation Of Sensorless Vector Control System Based On MRAS

Permanent magnet synchronous motor(PMSM) vector control system requires accurate rotor position signal to implement the magnetic field orientation. Usually, it adopts the mechanical position sensors such as optical encoder and hall sensors to detect the speed and position of the rotor. But these mechanical sensors increase increase the volume and inertia of the motor, the cost of the system and reduce the reliability of the system. Therefore, the research of sensorless vector control has become a hot topic in the study of PMSM control system.The research is based on PMSM. This article uses TMS320F2812as the core chip and design the sensorless vector control system based on Model Reference Adaptive System(MRAS).The article describes the basic principle of MRAS algorithm which is put into the sensorless vector control system of PMSM. The system uses MRAS algorithm to identify the speed and rotor position. This article makes the following two improvements:Firstly, this article proposes a mixed MRAS algorithm. An simplified MRAS model is built under the vector control strategy of id=0. Mix the simplified MRAS with the traditional MRAS through smooth handoff algorithm to form the mixed MRAS algorithm.The mixed MRAS algorithm has better dynamic performance and higher steady-state identification accuracy.Secondly, this article proposes a MRAS algorithm with the stator resistance identification. Actually, the stator resistance will vary with the changes of the temperature and the stator current. However, the stator resistance makes great impact on the MRAS algorithm which identifies the speed of the rotor. If the value of stator resistance set in the system doesn’t match its actual value, the estimated speed will oscillate, and then the system won’t work properly. The MRAS algorithm with the stator resistance identification can identify both the rotor speed and the stator resistance, which greatly improves the robustness of the system.Build the hardware platform with TMS320F2812. The hardware circuits include a control board and a power board. Complete the software design under CCS3.3and the entire system can work properly.