A recent trend in advanced drives control has enabled an AC motor to behavior like a separately excited DC motor. This goal has been almost achieved since introducing the vector control principle. The main disadvantage of vector control methods is the presence of non-linearity in the mechanical part of the equation during the changing of rotor flux linkage.
Although good results from field-oriented control have been observed, attempts to obtain new control methods are being made. Non-linear control of induction motors was first presented in . It introduced a novel mathematical model for induction motors, which made it possible to avoid using sin/cos transformation of state variables. The model consists of two completely decoupled subsystems, mechanical and electromagnetic. It has been shown that in such a situation it is possible to have non-linear control and decoupling between electromagnetic torque and the rotor linkage flux. Decoupling between torque and the square of rotor flux has been obtained, after assuming some simplification [1,2,25,26]. Works that discuss non-linear control of dynamic systems include [1–28].
When a motor is fed by voltage source inverters, and when the rotor flux linkage magnitude is kept constant, the non-linear control system control is equivalent to the vector control method. In many other situations, this new idea gives simplicity of the structure and good response [2,25,26].
The main disadvantage of vector control methods is ...