System reconfiguration under open-switch faults in a doubly fed induction machine

The aim of this study is to present system reconfiguration for a doubly fed induction machine (DFIM) after an open-switch fault is detected in its back-to-back converters. The open-switch fault and its detection for the scheme are discussed first. System reconfiguration is applied to operate the DFIM after the fault is detected. A four-switch converter topology with dc-link midpoint connection is selected to reconfigure the system. An existing pulse-width modulation method is investigated and applied to reconfigure the system, but uncontrollable capacitor voltage drift occurs. This study proposes a technique to solve the drift problem and also improve the quality of the dc-link voltage. Its effectiveness is substantiated by both simulation and experiment.