Otimização da estrutura de acionamento para o controle de posição radial de um motor de indução trifásico sem mancais com enrolamento dividido

Abstract

In bearingless motors or self-bearing motors, the motor and bearing functions are combined, that is to say, in the stator of the machine circulate currents that produce on the rotor besides the torque, also radial forces that support the rotor in the center of the stator. Thus, these machines do not suffer from the common wear of mechanical bearings, do not require lubrication, operate without noise and are suitable for applications with high rotational speed. In spite of all the advantages of the self-bearing motors, their operation requires a drive structure equipped with many components such as: electronic power switches, sensors, electronic interfaces and digital signal processors that make their application more expensive. The purpose of this work is to optimize (decrease) the number of components necessary for the operation of the self-bearing motors, both for the control of the radial position of the rotor and for its drive, To achieve this, the following strategy was designed: instead of controlling the currents of the three phases, which requires the control of six currents, the currents of only two are controlled, the current of the third one is produced by the sum of the first ones. With this, the control structure would only use 4 electronic switches (IGBT), 4 drives (electronic interface for IGBTs), 4 current sensors and 4 current controllers, instead of 6 of these devices and 6 required current controllers for control with the three phases. This strategy was implemented in a prototype of 250- watt induction self-bearing motors that works in the upright position. The experimental tests showed similar results to those obtained with three-phase control techniques.