Robust Speed Controller of a Bearingless AC Motor Type Divided Winding, Based on a Conventional Squirrel Cage Induction Motor

This paper shows a new approach to control the speed of rotor field oriented for a bearingless AC Motor type divided winding for a conventional squirrel cage Induction Motor of 3.75 kW, 380V, 4-poles, 60Hz, 1.04 Nm. To implement the control strategies, was chosen the rotor flux referential (R-FOC). This referential is based on decomposition of the stator current into two components done in a decoupled manner: flux controlled by stator direct-axis current and torque controlled by quadrature-axis current. To implement the control algorithm, was chosen the rotor flux referential, which is being estimated through the stator winding currents and the rotor speed. The vectorial speed controller operates in synchronism with the radial positioning controller, but these controllers should work with low mutual influence.