On-line switched control of a six-phase induction generator in faulted mode

Abstract

The operation of multiphase machines in open-phase fault conditions is always associated with undesirable ripples in torque and power, even in steady state conditions. In the literature, several methods have been proposed to reduce these oscillations considering a fixed-fault situation without taking into account the transient behavior during the modification. In this way, this paper deals with the design and implementation of a multi-control system for all possible open-phase situations of a symmetrical squirrel cage six-phase induction generator (SC6PIG) up to three opened phases in such a way to extract a qualified electrical power. For this, a general model of the SC6PIG in healthy and open-phase fault situations is employed to design the multi-control system. The control systems are re-arranged regarding the situation of the generator in different open-phase fault conditions to provide the output power as close as in healthy mode. A simple detection system is associated to define the state of the generator (number and type of opened phases in faulty operation) and to switch to the appropriate control system. Furthermore, in order to minimize the transient problems during the switching process between the different control systems, an on-line initial condition setting is imposed to the control systems during the motion. An experimental set up including a SC6PIG driven by a permanent magnet dc motor has been built to prove the capacities of the proposed on-line switched control system in different cases such as healthy, one opened phase and two opened phases situations with smooth switching.