| Vector controlled induction motor (IM) drives normally incorporates position sensor, phase current sensors, dc-link voltage sensor and dc-link current sensor. In this research, a sensor fault-diagnosis and fault-tolerance scheme for IM drives is presented that will allow IM drive system to operate properly in the event of sensor failures. The scheme will automatically diagnosis system sensors in the event of sensor fault or sensor recovery, and will automatically reconfigure the controller, adopt the best method to get the best performance out of the remaining sensors.; Specifically, a novel current regulation method, Digital Delta-Hysteresis Regulation (DDHR) scheme, was presented wherein all the phase currents can be fairly accurately reconstructed and controlled with only the dc-link current sensor. Thus, phase current sensors fault-tolerance was accomplished. In addition, MRAS position sensorless control was adopted to provide position sensor fault-tolerance. Moreover, a combination of DDHR and MRAS will provide fault-tolerance of both phase current sensors and position sensor, and the drive system will maintain vector control even when all the phase current sensors and the position sensor are lost. Simulation and experimental results are provided to show the effectiveness of the proposed scheme. |
