Principles of vector control in cage motors: an easy quantitative approach via space-phasors

The paper presents a study of a current controlled cage induction machine, with focus on the spatial distribution of quantities, and their angular relationship. It shows that the relative position of torque producing quantities is determined by the slip frequency and rotor time constant only. It also shows that vector control techniques do not improve the steady state operation, as the machine naturally adjusts itself for optimum conditions of torque production. The changes required in the stator MMF space phasor to yield step changes in torque are established analytically and quantitatively. The findings are supported by both digital simulation and experimental evidence