Sliding Mode Control Strategies for Induction Motors

Abstract

The control issues of an induction motor (IM) widely use current regulator, because, it is a basic block in high performance drive system based on sliding mode (SM) approach. Chattering usually is caused due to unmodelled dynamics in the system, e.g. the lag or transport delay in the inverter or the sensors. This control problem is eliminated with the help of an observer based solution. Hence, we introduce a concept of speed and and#64258;ux observers in the inherited qualities of the sliding mode control (SMC) based on current control. The report presents SM observers for rotor and#64258;ux and speed of an IM. The observer design is based on the stationary reference frame model of the IM. The novelty is the design method: and#64257;rst, a sensored SM and#64258;ux observer is developed from stator currents and rotor speed, which is made sensorless by replacing the speed with a speed estimate. Second, sensorless SM speed observer based on stator currents and rotor and#64258;ux. The convergence of both observers can be guaranteed and analyzed by using Lyapunov function. The effectiveness and robustness of both observers are evaluated under the inand#64258;uence of parameter variations and disturbances. The theoretical control design is veriand#64257;ed through simulation results and experimental tests. This report also investigates speed and and#64258;ux tracking control method based on quasi continuous SMC for IM. Speed and and#64258;ux tracking has been carried out by using quasi continuous second order SMC (QC2SMC) and quasi continuous third order SMC (QC3SMC) with robust differentiators. These controllers exhibit higher accuracy in realization, fast tracking response and completely eliminates chattering effect, usually caused due to an unmodelled dynamics in the system. To overcome the problem of conventional SMC, QC2SMC is and#64257;rst designed. QC2SMC produces continuous control and less chattering. Chattering exists during the control action of QC2SMC when the system remains on the sliding manifold. However, It is difand#64257;cult to select SM controller gain that minimizes the reaching time on sliding