Chattering-free High-order Terminal Sliding-mode Control For Sensorless Induction Motors

Induction motor (IM) has held an important position in the national productfield due to its simple structure, low cost, reliable working and adaptable. With thedevelopment of technology, the appearance of more and more high precisiontransmission occasions demand high performance of IM drives. Speed sensorlessvector control (SLVC) has become a research focus for scholars with the advantagesof high performance, no rotating mechanism sensor and high reliability. So furtherstudying SLVC, and improving its dynamic and static characteristics will have majorimplications for the use of IM drive in high precision occasions.For high performance SLVC system, combined with chattering-free high orderterminal control, control and observe algorithm is studied in this paper. The practicalresearch content is as follows:On the basis of the analysis of IM mathematical model, a double closed loopvector control algorithm is designed. The simulation results verify the correctness ofthe designed algorithm. Then the IM control system experimental platform is built,with DSP TMS320LF2812as control core. After finishing the plan of main circuitand program, preliminary experiments are conducted, and the experiments resultanalyses are carried out.Based on proposed chattering-free high order terminal sliding mode control,the speed and current controller are designed respectively under two-phasesynchronous rotating coordinate system. Lyapunov stability theorem is used toprove its stability strictly. The simulation results show the proposed method canimprove the control accuracy and robustness of IM dual closed-loop vector control.To realize the induction motor rotor flux observation, in two phase static frame,a rotor flux observation with chattering-free high order terminal sliding modecontrol method is proposed. The problem of unable to convergence within finitetime and chattering are eliminated with the proposed method. The simulation resultsshow that the accurate rotor flux is obtained with the design observation.To realize the SLVC algorithm, a stator current observer is devised, and thechattering-free high order terminal sliding mode control is used to make the currenterror converge in finite time without chattering. Then a flux and speed observer isplaned to observe the flux and speed, and the simulation results support the theory.