Speed Estimation And Parameter Identification Of Three Phase Induction Motor

Induction motor can operate very fast, and its capacity is very large, so it has been used widely in various industry. During the existing AC speed control methods, speed closed-loop can effectively improve the control accuracy compared with speed open-loop. This needs the installation of speed sensor to detect speed and feedback speed signal to control system. But speed sensor seriously affects the system's simplicity and reliability. Maintenance is also not convenient. Even to the extent that not all motors are able to meet the installation conditions restricted by the motor structure and operation environment. Therefore, through the collection of physical quantities, such as stator voltage and current, to estimate the speed is a practical and feasible scheme. In addition, regardless of speed estimation or other model of speed control system, the performance of the merits heavily dependents on the motor's own parameters, including the stator resistance, rotor resistance and leakage inductance, mutual inductance, etc.). So to obtain accurate motor parameters becomes the key of all the work. On the basis of understanding and analyzing the motor dynamic mathematical model, this paper focuses on the realization of the two aspects, speed estimation and parameter identification.Firstly, through analyzing the existing speed estimation methods, the model reference adaptive system(MRAS) is selected to estimate the speed. Based on rotor flux linkage MRAS and based on state observer MRAS are used as the two major branches, this paper has carried out a more in-depth theoretical analysis, while the traditional method has been improved.MATLAB simulation experiments compare the control precision and dynamic performance of the above methods, and choosing improved MRAS based on rotor flux to be elaborated. From the simulation results, we can see the superiority of the improved method clearly.Secondly, in view of the parameter identification problem, this paper adopts two methods,one is the off-line identification method, the other is the on-line identification method.Off-line identification method is relatively simple and can provide reliable initial value of basic physical parameters, which has a very good practical value for many no conditions to predict motor parameters used in the occasion. In order to avoid the influence of the temperature and other environmental factors on the motor parameters, the stator resistance and rotor time constant are identified on-line in the paper. The simulation results show that the online identification has better tracking performance.Finally, this paper takes the motor control special chip TMS320F28335 as the control core, building the system hardware platform, using C language to complete the speed estimation and parameter identification software programming. The experimental results are consistent with the simulation results, and verify the rationality of the design method.The design method of speed estimation and parameter identification mentioned in this paper has wide applicability, and has more practical significance to the speed sensorless detection system and AC speed regulation system.