Mohamed Trabelsi

ACAlternating CurrentBATBattery SystemCIICarbon Intensity IndicatorDCDirect CurrentDGDiesel GeneratorECAEmission Control AreaEFEmission FactorEMSEnergy Management SystemETSEmissions Trading SystemE...

This paper presents a robust fault-tolerant control (FTC) strategy for a multiphase PMSM-based propulsion system. The proposed approach combines an innovative super-twisting sliding mode controller (IST SMC) with a fault-tolerant model of the machine when an open-circuit fault occurs. The electrical propulsion system mainly has a two-line structure with a single DC source, a five-leg inverter and a Five-Phase Permanent Magnet Synchronous Motors (5-Φ PMSM), suitable for marine propulsion applications. Two main scenarios are investigated in this work. Firstly, if an open-phase fault occurs in one of the two 5-Φ PMSMs, a reconfiguration step of the machine control is applied in order to improve the performance of the propulsion system and to ensure the continuity of operation. Then, if the fault occurs in one of the two inverters, the faulty one is removed and the electrical series connection is made between the two machines, where they are powered by a single five-arm inverter, thus ensuring the continuity of operation of the system. Considering these two scenarios, a comparative analysis is made between the IST SMC and the classical PI controllers in terms of robustness to uncertainties, external disturbances and tracking accuracy for healthy and faulty operation modes, and during transient states.

This paper deals with the control of two five-phase permanent magnet synchronous motors (PMSMs), which are connected in series and operating at different speeds and torques. The topology under study is intended for use in an electrical naval propulsion system. The backstepping control strategy, which uses the Lyapunov stability concept, is employed to control the speed of the two machines considering the series connection of the PMSM stator windings. A comparative study, with respect to classical Vector Control (VC) using PI regulators, is provided to demonstrate the robustness of the proposed control strategies in both healthy and faulty conditions. Typically, dual PMSMs in series cannot operate in the degraded mode in the event of faults. This study optimizes their operation by adapting to such modes, including faults caused by symmetrical parameter changes or by an asymmetrical High Resistance Connection (HRC) in the stator windings, thereby ensuring continuity of service. The HRC is investigated and verified in one stator phase, in two adjacent stator phases and in two non-adjacent stator phases, as well as in a symmetrical HRC fault across all phases. Matlab-based simulation results validate the control design to achieve the desired performance and prove the effectiveness and the asymptotic stability of backstepping control for two series-connected 5-Փ PMSMs, thereby providing redundancy for the naval electric propulsion system.

This paper aims to improve the effectiveness of an isolated water pumping system (IWPS) based on parallel wind turbine powertrains by using a nonlinear Integral Backstepping Controller (IBSC). The powertrain system with parallel Permanent Magnet Synchronous Generators (PMSGs) is used to ensure the continuity of the operation and to optimise the efficiency of generators. The effective wind speed of a wind turbine is estimated using an Extended Kalman Filter (EKF) instead of using anemometers. Moreover, the Tip Speed Ratio (TSR) method based on an Adaptive Fuzzy Logic Controller (AFLC) is performed to apply the MPPT algorithm. To evaluate the efficiency of the EKF estimator, the covariance and correlation coefficient between the estimated and measured wind speeds are computed for Ts = 1 s, while the AFLC and nonlinear IBSC controllers are evaluated in comparison to basic PI controllers. For the wind speed estimation, the covariance and correlation coefficient results demonstrate that the EKF estimator has high accuracy with a 98% similarity between the estimated and measured wind speeds. For the power extraction, the TSR based on the adaptive FLC controller can extract slightly more wind energy than the PI controller. For tank level control, the nonlinear IBSC controller improves the efficiency of the wind turbine water pumping system by reducing the DC voltage surge and the overshoot of water level observed with the PI controller.

This paper presents a diagnostic method of inverter open‐switch and open‐phase faults in multiphase permanent magnet synchronous motor (PMSM) drives. First defined are adequate variables called virtual current vectors. The projection of the zero‐sequence current component on these variables was used to define two simple fault indices. High sensitivity to fault is thus induced but with a good robustness to transient states and variation of machine parameters. The mathematical development of the proposed method is provided and supported by experimental tests conducted on two prototypes of multiphase machines in the laboratory: sinusoidal and bi‐harmonic PMSMs. The experimental results confirm the effectiveness and the robustness of the proposed method and its capability to detect the single and multiple open‐switches and open‐phase faults in the electric drive.

In normal operation mode, sensorless speed‐controlled motor drives should be more reliable, less expensive and less bulky than their counterparts with a speed sensor. The sensorless drive structure allows avoiding the electromagnetic and vibratory sensitivity of the mechanical sensor, the additional connecting circuits, additional space for the sensor, its price and maintenance requirements. However, in postfault operation mode, the robustness of speed sensorless control strategies has been poorly addressed in the study. Accordingly, this study deals with an experimental study of the robustness and the availability of speed‐controlled induction motor (IM) drives without speed sensor in the presence of inverter open‐switches faults. For that purpose, a super twisting algorithm‐based observer for motor speed estimation is proposed for experimental investigation. Experimental results are performed upon 3‐kW IM drive by using dSPACE digital signal processing controller board. Experimental investigations evaluate the performances of the method used for the control without speed sensor in prefault, postfault and regeneration operation modes.

This study deals with a mixed model‐based and signal‐based approach for sensorless speed‐controlled induction motor drive (IM) and insulated‐gate bipolar transistors open‐switch fault diagnosis. In comparison to the classical sensored drive systems, this structure presents particular characteristics in post‐fault operation mode which can be taken into account for fault detection and identification process designing. Firstly, the fault effects analysis is achieved in the abc frame of the IM. Based on such analysis, a diagnostic algorithm, using the measured and estimated currents, is used to define the fault indices, which allow the detection of single open‐switch, multiple open‐switch and open‐phase faults. The sensorless control algorithm used for rotor speed estimation, as well as the fault diagnostic algorithm, are all based on a first‐order sliding mode observer. In addition to the simplicity and the fast fault detection, there are no‐additional sensors or extra‐hardware used by the proposed method. Experimental results, based on a dSPACE DS1104 controller board and a 3‐kW induction machine, are shown to validate the proposed strategy.

Even if intrinsically a five-phase machine can work with one opened phase, thermal constraints (temperatures in windings and Permanent Magnets) impose to decrease the mean torque in faulty operation mode. In order to elaborate optimum control which ensures safety and maximum torque, it is necessary to estimate in real-time the temperatures induced by the currents imposed in the remaining healthy windings of the machine. For a five-phase prototype, a multi-nodal thermal modelling which can take into account irregular losses and flow distribution has been developed. It is based on Electromagnetic FEM results for the losses and CFD calculation analysis. Results are presented in normal and faulty operation modes.