Research On Stable Operation Technology Of Induction Motor Sensorless Vector Control System

Induction motor sensorless vector control system uses adaptive algorithm to observe the speed in real time,instead of encoder that is expensive,large volume and low reliability,it has been widely used because of its simple structure,low cost,high reliability advantages.Full-order adaptive observer control algorithm is researched.Feedback matrix is designed based on the principle of multiple poles,the feedback matrix and the traditional speed adaptive theory constitute the full-order adaptive observer algorithm,through the experiment proved that motor has relatively stable and good dynamic performance at high speed,but there are still some problems,the speed estimation error is bigger in the low speed,especially in extremely low speed region.To solve the above problem,a improved full-order adaptive observer is designed.The full-order adaptive observer consists of the feedback matrix and the speed adaptive theory.Through the establishment of considering nonlinear inverter voltage error state observer error equation and the analysis of influence of nonlinear voltage error of inverter on estimated speed,a feedback matrix is designed to reduce the influence of nonlinear voltage error of inverter on estimated speed,at the same time,the traditional adaptive theory is improved,and the compensation amount equivalent to the flux error caused by the nonlinear voltage error of the inverter and the voltage drop of the stator resistance is added on the basis of the traditional adaptive theory,and the amount of this compensation has a certain degree of adaptability,so that the speed estimation has high accuracy at low speed.The design of the full-order adaptive observer is based on the accuracy of the motor parameters.In actual working conditions,the motor parameters will change under the influence of the environment,among which the variation of the rotor time constant will lead to torque fluctuation and affect the system performance.In order to improve the performance of the system,a model reference adaptive system based on reactive power model is used to update the rotor time constant online.