Research On High Performance Induction Motor Speed Sensorless Vector Control System

The induction motor(IM)have occupied a dominant position in the electrical power drive field based on its compact design and technology.Various high performance AC speed control technologies are widely researched and applied.The IM vector control(VC)system based on the rotor field oriented control technology has brought perfect dynamic performance to match DC driving system.Speed sensorless control of IM promotes the simplicity and robustness further.However,there are several problems must be solved in the present research,which include the speed estimation,rotor flux observation and controller parameters optimizing.Extended State Observer(ESO),extending the state to observe the rotor flux by constructing motor state equation,realizes the simultaneous speed identification and flux observation for induction motor by combining with the Model Reference Adaptive System(MRAS)technology.Active disturbances rejection controller(ADRC)is a kind of new nonlinear controller,which is characterized by its compensation total disturbance of system and largely model independent.Speed-sensorless VC strategies of IM as the application background,deep and systematical research is made,covering the content of rotor flux observer design,rotor resistance identification,stator resistance identification,speed estimation,robust controller design and optimizing its parameters.ESO is an effective state estimation algorithm of IM,the rotor flux based on the ESO has a strong robustness when rotor resistance changes within a large range.But it has two major defects:(1)bad robustness to the variation of stator resistance;(2)lack of compensation ability to the output deviation of rotor flux observer.To overcome these disadvantages,the closed loop ESO is introduced to estimate the rotor flux,which can improve the estimation performance of compensation total disturbance and the output deviation of observer.Furthermore,the stator resistance adaption and reconstructed errors of MARS were also qualitatively discussed,which overcomes problems such as pure integration and voltage drop caused by the stator resistance at low speed.Incidentally,the reconstructed errors above consist of rotor flux differential signal and stator current estimation.Simulation and experiment results illustrate that it has satisfactory estimation performance and IM parameters variation robustness.The rotor constant of IM are supposed as constant in IM indirect field oriented control system,nevertheless,rotor constant is a time varying parameter caused by the uncertain rotor resistance.A novel rotor resistance identification method based on reactive-power reference model is proposed.The proposed identification strategy has simple structure,less tuned parameters,high precision and robustness,the validity and practicability is verified by simulation results.Speed estimation strategy is the key technology of sensorless vector controlled IM,however,the traditional speed observer do not take into account its parameters time varying and need to improve.Therefore,an interactive MRAS speed identification strategy based on the MRAS theory is presented.This interactive MRAS method of speed identification using ESO flux model as reference model and motor current mode as an adjustable model constructing MRAS speed observer,and exchanges adjustable model reference model in real-time to estimate the stator resistance.The proposed method robust to large-scale rotor resistance,stator resistance variations and rated torque at low speed,and better dynamic performances of speed identification and torque response ability were obtained.Simulations and experimental results prove the validity and practicability of the algorithm.Researching on adaptive robust controller is an important content of VC system,which can avoid the disadvantages of PI controller.The traditional PI controller sensitive to IM parameters and achieves poor adaptive ability in the speed adjustment process.A novel controller based on ADRC is proposed in the system,and special parameter optimization method based on ECARLA is employed for the ADRC.ECARLA is a kind of high efficient reinforcement learning strategy and can absolutely getting the global optimum solution.The ADRC can achieve strong robustness to large scale time-varying parameters and torque disturbance in VC system,its the dynamic control performance and speed adaptive ability are superior to the traditional PI controller,Simulation result has verified the rationality and validity of the scheme.The proposed state and parameters estimation methods in this paper are experimented using the experiment platform with AC drive system.A nonlinear regulator is proposed based on ADRC,which can increase the precision of the rotor speed and load torque of IM efficiently.The IM parameters identification methods also have high precision,which can satisfy the request of high performance speed sensorless control of IM.