Study On Control Strategy Of Permanent Magnet Submersible Motor With Position Sensorless

Oil is an indispensable energy in the development of society. The world’s demand for oil is increasing day by day, and the technology of oil exploitation is also increasing. Due to the current exploitation of oil field, the machine used mostly is the traditional induction motor,and there are many problems such as high energy consumption, and other poor performances.However, if the permanent magnet type of submersible motor is used, it will have an important effect on reducing the cost of oil production and improving the system efficiency. Therefore,in the background of advocating national energy-saving emission reduction, the use of permanent magnet submersible motor for oil recovery technology is worthy of popularization and application. It is necessary to study the vector control of the position sensorless for the special working condition of submersible motor.This thesis is based on the need of the practical application of the permanent magnet submersible motor, and the problem of the rotor position and speed for sensorless is analyzed.The advantages and disadvantages of the sensorless control algorithm are compared, a simple and robust of sliding mode observer method is used to detect the rotor position, and the performance requirements of vector control for permanent magnet submersible motor are realized.Firstly, the structure and characteristics of the permanent magnet submersible motor are briefly introduced and analyzed. The relevant physical model and its mathematical models are all built, and the control method of vector control is determined. The compensation algorithm for vector control of permanent magnet submersible motor on the condition of the long cable is also studied. The principle and implementation of space vector pulse width modulation technology are briefly described, and the simulation is carried out.Secondly, according to the control theory of sliding mode variable structure, the estimation method of the rotor position and speed of the traditional sliding mode observer is analyzed. Then, based on the problem of chattering and accuracy in the estimation of the rotor position of the traditional sliding mode observer, an improved sliding mode observer scheme is proposed. Kalman filter for the two time filtering is used, saturation function instead of switching function, and finally the use of phase locked loop technology for position and speedestimation. For the high temperature environment of oil well may cause the change of motor resistance parameter, the parameter identification of stator resistance is added to improve the estimation accuracy. And the starting of the motor is analyzed.Finally, the simulation model of vector control system based on sliding mode observer is built, simulation and analysis are carried out on the traditional sliding mode observer and the improved sliding mode observer. In view of the various working conditions in the oil recovery system, the estimation scheme of rotor position and speed of improved schemes is also simulated, and the simulation results show the feasibility and effectiveness of the proposed improved schemes.