محمد جناتی

Current sensors are required in Field-Oriented Control (FOC) strategies of Three-Phase Induction Motor (TPIM) drives. Nevertheless, the current sensors are subject to different electrical/mechanical faults which reduce the safety and dependability of the drive system. Single phase current sensor Fault-Tolerant Control (FTC) for sensorless TPIM drives using flux observer and Extended Kalman Filter (EKF) is proposed in this research. In the suggested FTC scheme, current sensor fault detection is based on axes transformation, a logic circuit is served as the fault isolation and reconstruction of faulted currents are achieved through flux observer and EKF. The presented FTC system is capable of detecting and localizing the current sensor fault and switching the drive system to tolerant FOC mode without the rotor speed measurement. The effectiveness of the suggested FTC system is confirmed by experiments on a 0.75kW TPIM drive platform.

Reliability for electric motor drive systems is very vital in some industries. Selecting an appropriate control strategy for driving an electric motor during fault conditions is one of the most important issues mainly for safety-critical applications. Recently, vector control (VC) strategies have been extensively developed for star-connected three-phase induction motor drives during single-phase cut-off fault (COF) based on two different transformation matrices (TMs). Despite the effectiveness of these methods during the fault, these control systems are very complex due to their extensive on-line computation. This paper presents two simple methods based on indirect VC (IVC) and direct VC (DVC) methods for controlling a star-connected three-phase induction motor during the fault condition. The fault in this paper is limited to single-phase COF which can occur in motor stator coils. In this paper, it is shown that using a suitable TM and some changes in the control parameters, it is possible to control the faulted drive system. Performance of the proposed control methods is verified using MATLAB software and DSP/TMS320F28335 controller board for a 0.75kW star-connected three-phase induction motor drive system. The achieved results show the good performance of the introduced control systems in different operating conditions. In addition, the results demonstrate the performance of the proposed VC strategies and that of the previous works are almost the same. However, the proposed VC methods in this paper need less modification in the structure of the standard VC strategy than the previous works.

The Vector Control (VC) of Y-Connected Induction Motor (YCIM) drives is entirely demanding task. Furthermore, YCIM under an Open-Circuit Fault in the Stator Coils (OCFSC) leads to deterioration of the VC. Consequently, the VC of YCIMs under an OCFSC requires a suitable design. This research focuses on an accurate and modified Field-Oriented Control (FOC) strategy for 3-phase YCIM drives under an OCFSC. Most of the recent papers studying VC of YCIMs under an OCFSC ignore the leakage inductance in the VC equations. This paper presents an alternative VC technique, considering the leakage inductance in the VC equations of YCIMs under an OCFSC. In the presented VC system, two asymmetrical Rotating Transformations (RTs) for the stator current and voltage quantities are proposed and employed. In the proposed scheme, the genetic algorithm is used to regulate the parameters of the Proportional-Integral (PI) controllers. The developed VC system provides an accurate control against an OCFSC and can be employed for different industries that need Fault-Tolerant Control (FTC) systems. The effectiveness of the proposed approach is validated through experimentation in the laboratory. The proposed control scheme gives good responses during both steady state and transient sate. In addition, the proposed VC system gives better performances during the post-fault operation compared to previous works in terms of speed and torque ripples.