Online controller modifying of a six-phase induction generator in phase opening occurrences

This study presents field oriented control of a squirrel cage six-phase induction generator (SC6PIG) when a phase fault is detected in order to minimize output power oscillations during phase opening. An unbalanced structure of squirrel cage six-phase induction machine (SC6PIM) has been modeled to analyze healthy and faulty conditions of the machine. According to the unbalanced structure of the machine, a suitable controller is defined in phase missing condition to minimize power oscillations. After fault detection by using a dedicated system, the controller used in healthy condition is switched to a new one regarding to the fault situation. For each controller, appropriate initial conditions are chosen to minimize the transient behavior of switching process between healthy and faulty controllers. The whole proposed system has been implemented on an experimental set up including of a six-phase induction generator coupled with a permanent magnet direct current (dc) motor. Experimental results prove the feasibility and show the improvement of power quality when the controller is modified in phase missing conditions. The experimental results are presented for one phase missing and they can also be obtained for two or three phases missing conditions.

I. Introduction

In industrial applications where high reliability is required, the traditional three-phase machines are more and more replaced by multi-phase machines which have more than three phases on their stator side [1] – [3]. Indeed, in faulted mode, a multiphase machine is still working so long as three phases are remaining. Among all the types of multi-phase machines, squirrel cage six-phase induction machines (SC6PIMs) are really popular due to the brushless and simple structure of their rotor.