Research On Speed Sensorless Field Control Of Induction Motor

With Extended Kalman filter (EKF) theory as the basis and the induction motor as a control object, this article focuses on the induction motor with speed sensorless at the wide range of speed control system.First of all, this article introduces the mathematical model of the induction motor,and the motor by voltage and current limits.To improve motor in dynamic characteristics of field-weakening control of regional objectives, current and voltage limiting field weakening control of area, come up with field weakening control methods. By restriction analysis of motor in a state of field-weakening conditions, changes of voltage, current and torque. Focus on several key issues, such as d-axis current generation and control, q-axis current base speed area, field-weakening control of interval and interval two,three specific limiting of regional policy, and voltage limiting size and decoupling method, q-axis current-limiting effects of change and brake on the motor. On the field-weakening control method for simulation, results showed that the field-weakening control method is effective.In addition, using the motor in two phase mathematical model of stationary coordinate system, design and build of the extended Kalman filter for speed estimates and it combined with current for calculation of rotor Magnetic chain and position angle, priority in the process of establishing EKF estimated speed in low-speed effects during the moment of inertia of the EKF. in the process of establishing EKF estimated speed is priority consider effecting during the moment of inertia of the EKF in the low-speed. To test the EKF estimation of dynamic characteristics to meet the requirement, in the EKF estimated speed in the system, consider to change of motor parameters of stator and rotor speed estimation for tracking results and effect of convergence. In internal of EKF setting different of noise covariance parameters to study the impact of speed estimation of the variance. With field-weakening control methods, establishing flux-weakening control system without speed sensor simulation, proved in the motor field-weakening operation process, the EKF algorithm is available.