Future practical developments in vector control principles

Proposes an industrial evolution of the well-known vector control principles towards an innovating alternative solution to direct torque control issues. Industrial control objectives are firstly defined in terms of dynamic performance robustness and harmonic criteria. The associated state-space model of an induction motor is here described in nonlinear form. Field oriented control is thus easily interpreted as an input-output linearization by state feedback in order to introduce concomitant direct torque and flux control. The main properties of direct torque control are also discussed according to industrial constraints showing some important drawbacks. The new principles of the proposed vector control are then explained through a geometric view of sliding modes/limit cycles concepts. An overview of the resulting discontinuous nonlinear state feedback is presented fully covering asynchronous, synchronous and square wave equivalent modulations of a voltage source inverter. Finally, experimental results are presented and discussed, demonstrating the high efficiency of the proposed method applied to an industrial test bench for induction motors