Modelagem e controle de um motor de indução multifásico com fases abertas

Abstract

The usage of multiphase machines has been investigated to improve the reliability of electric drives. Multiphase machines have various advantages when compared to the tree-phase counterparts and are attractive to many applications, such as those of high power and electric propulsion. Fault-tolerance is one of their main advantages, since the multiphase motors can operate with open phases. However, it is necessary an adequate control technique to guarantee the post-fault operation with minimum performance degradation. The objective of this work is to model and characterize the operation of a nine-phase induction machine under open phases faults and to propose control methods leading to fault-tolerant operation. Modeling of the machine with open phases in a synchronous reference frame is presented. In order to produce a balanced magnetomotive force and to eliminate the torque ripple, an adequate field-oriented control technique is developed for open phases operation. Additionally, it is proposed a control of the currents of the zero-sequence subspace, in such a way that the post-fault phase currents in the remaining phases will have the same magnitudes, assuming no neutral current connection. Furthermore, this control scheme allows the machine to operate with its nine phase currents unbalanced, while still producing a balanced magnetomotive force. This degree of freedom can be used to routing the power flow among the inverter’s phases, in order to balance the temperature of the inverter switches. As an overall result, the fault-tolerance of multiphase drives can be improved, achieving a controlled performance under normal and faulty conditions, which is of great interest for applications that require high availability. The developed control techniques are validated in online co-simulations in closed loop with the nine-phase induction motor modelled in finite elements software and in real time simulations via hardware-in-the loop.