Research On Speed Sensorless DTC System Of Induction Motor Based On Full-order Flux Observer

Based on the research of the speed regulating characteristic of induction motor, this paperpresents a full-order flux observer principle. On the depth study of the observer principle, this paperuses direct torque control (DTC) technique in the control system and analyses speed sensorlessmethods of induction motor. Then, a DTC system based on full order flux observer is built and a lot ofexperiments are conducted.The basic principles of space voltage vector are elaborated in-depth, at the same time, twodifferent space voltage vector modulation modes are compared, and also focused on analysis of theSVPWM physical meaning. The SVPWM technique is combined with the DTC scheme to suppressthe voltage ripples effectively.The principles of DTC and its structure are discussed in detail, and also some problems existedare analyzed. On this basis, PI regulating concept is utilized in the DTC system, and its characteristicssuch as convenient system implementation, fast torque response and lower torque ripple arepresented.Design a full order observer with variables of stator current and rotor flux. At the same time, thefeedback gain matrix of this observer is presented in detail. The speed of motor and parameterestimation method gained from the full order observer theory can not only estimate the speed of themotor accurately, but also identified the stator resistance effectively.The speed sensorless DTC system with full order flux observer is built and correlativeexperimental researches are implemented on the system. The control strategies proposed in thisdissertation are validated by the experimental results.