Research On Speed Sensorless Vector Control Based On Mras For Ship Induction Propulsion Motor

Power electronics and motion control technology are regarded as the second great technological innovation following computer technology, which have dramatically changed the sources and life of people. During the development of power drive system, AC motor and DC motor electrical drive coexist in various industrial fields. For the moment, AC speed regulating system is booming with the maturity and popularity of the new power electronic components, and has gradually replaced DC motor to be the unanimous choice of propulsion motor in the ship electric propulsion system due to its advantages in construction and reliability. The paper focuses on the speed sensorless vector control method, which has a certain practical significance to the theory study of the marine electric propulsion system in our country.The paper analyzes the state of the development of induction motor speed sensorless control system, summarizes the merits and demerits of all kinds of speed identification methods. Based on the study of the induction motor vector control principle and AC induction motor’s mathematical models in three coordinates, a induction vector control system simulation model based on current hysteresis PWM modulation strategy and direct rotor field orientation is created in MATLAB/Simulink. The simulation results are achieved by means of the parameters of a three phase squirrel-cage induction motor in the lab, at the same time, the analysis is practiced. The paper adopts model reference adaptive method as the speed identification method, selects motor rotor flux voltage equation as the reference model of model reference adaptive system and rotor flux current equation as the adjustable model. The adaptive rate is deduced by Popov over stable theory, and its corresponding speed identification model is built in MATLAB/Simulink, the simulation results validate the accuracy of the model identification method. The block diagram of vector control system based on SPWM induction motor without speed sensor is depicted after studying the speed sensorless vector control technology. A power-fed motor experiment platform simulation model which is composed by two squirrel-cage motors connected through a mechanical shaft is established. Both of the motors adopt speed sensorless vector control pattern. The simulation results prove that the model could operate stably under the situation that the propulsion motor sets the speed while the load motor sets the electrical torque.At last, power-fed motor experiment platform is designed and realized, which is constituted by two three-phase squirrel-cage motors, host computer WINCC, slave computer, SIEMENS S7-300PLC and SIEMENS S120high performance frequency conversion control system. When the platform operates, one of the motors runs as a motor to simulate the ship propulsion motor, the other practices as a load motor to imitate the ship propeller load characteristic, the latter usually runs as a generator. The devised simulation system is physically validated by plotting the curve of the signals of the current, speed and torque measured in the system.