Synthesis of an improved diagnosis method for open IGBT faults dedicated to FSTPI fed IM drives

Abstract

FSTPI is given an increasing interest especially in many industrial applications such as aeronautics, robotics, renewable energy conversion systems and automotive as far as cost-effectiveness is concerned. Nevertheless, This reduced structure inverter is sensitive to several faults. In order to perform diagnostic speed, and to avoid false alarms caused by speed and load fast variations, an improved method to diagnose open IGBT faults in FSTPI fed IM drives is proposed. This enhanced method is based on the information yielded from the current's slope combined with those yielded from the normalized currents. The proposed diagnostic method is simple and just requires the current's sensors avoiding the use of another hardware or extra sensors. This means that the implementation of this method and its integration into the control system become easier and consequently, the cost of the drive systems decreases. To rely better dynamic performance, the direct RFOC strategy is applied to control the speed of the IM fed by FSTPI. Simulation results, which are presented and commented, have proved the high performance, under distinct operating conditions, of the proposed diagnostic method in terms of fast fault detection associated with a high robustness against false alarms.