Ngac Ky Nguyen

A Self-Learning Solution for Torque Ripple Reduction for Nonsinusoidal Permanent-Magnet Motor Drives Based on Artificial Neural Networks

This paper presents an original method, based on artificial neural networks, to reduce the torque ripple in a permanent-magnet nonsinusoidal synchronous motor. Solutions for calculating optimal currents are deduced from geometrical considerations and without a calculation step, which is generally based on the Lagrange optimization. These optimal currents are obtained from two hyperplanes. This paper takes into account the presence of harmonics in the back-EMF and the cogging torque. New control schemes are thus proposed to derive the optimal stator currents giving exactly the desired electromagnetic torque (or speed) and minimizing the ohmic losses. The torque and the speed control scheme both integrate two neural blocks, one dedicated for optimal-current calculation and the other to ensure the generation of these currents via a voltage source inverter. Simulation and experimental results from a laboratory prototype are shown to confirm the validity of the proposed neural approach.

Fault-Tolerant Operation of an Open-End Winding Five-Phase PMSM Drive With Short-Circuit Inverter Fault

Multiphase machines are well known for their fault-tolerant capability. Star-connected multiphase machines have fault tolerance in an open circuit. For an inverter switch short-circuit fault, it is possible to keep a smooth torque of a permanent magnet synchronous machine if the currents of the faulty phases are determined and their values are acceptable. This paper investigates fault-tolerant operations of an open-end five-phase drive, i.e., a multiphase machine fed with a dual-inverter supply. Inverter switch short-circuit fault is considered and handled with a simple solution. Original theoretical developments are presented. Simulation and experimental results validate the proposed strategy.

Real-Time Switches Fault Diagnosis Based on Typical Operating Characteristics of Five-Phase Permanent-Magnetic Synchronous Machines

A novel centroid-based diagnostic method of the power switches in five-leg voltage source inverter is proposed in this paper. Using a vectorial multimachine description, a five-phase drive presenting an opened switch or an opened phase faults has typical operating characteristics in comparison to classical three-phase drives. Based on such characteristics, this paper aims to provide a simple and robust diagnostic process for switches fault regardless of the shape of the back electromotive forces (harmonic components) and the transient states due to the load variation. Original theoretical developments are presented. Experimental results are shown to validate the proposed strategy.

Different virtual stator winding configurations of open-end winding five-phase PM machines for wide speed range without flux weakening operation

This paper presents a specific control strategy of double-ended inverter system for wide-speed range of open-end winding five phase PM machines. Different virtual winding configurations (star, pentagon, pentacle and bipolar) can be obtained by choosing the appropriated switching sequences of two inverters. The motors speed range is thus increased.

A comparative study of two fault-tolerant dual-motor drive topologies under short-circuit inverter switch fault

This paper analyzes two dual-motor fault-tolerant topologies for aerospace thruster application. The first structure supplies independently both machines while the second one connects them in series for reducing the number of transistors and offering a capability of energy management between the sources. Inverter short-circuit fault is considered. Based on the peak-currents obtained in simulation in degraded mode without reconfiguration and with two different reconfiguration strategies, the two proposed topologies can be compared in economic and technical aspects.

Fault-Tolerant Optimal-Current Torque-Controlled Five-Phase PMSMs with Open-Circuited Phases: Position Self-Sensing Operation

All-electric vehicles should be made more reliable in such way one can continue driving even after the event of one or more faults in the electrical drive. For this, the use of multiphase (more than 3 phases) electrical machines is considered here due to its redundant feature. An additional technique to increase reliability is to replace sensors by observers. This paper studies the feasibility to control the torque in multi-phase permanent magnet synchronous drives without a position sensor, with the lowest Joule losses, and this for a healthy as well as for a faulty operation with one or more phases open-circuited.

Experimental Investigation of Inverter Open-Circuit Fault Diagnosis for Biharmonic Five-Phase Permanent Magnet Drive

This paper proposes a procedure that is suitable for experimental investigation of real-time open-switch and open-phase faults diagnosis of a five-leg voltage source inverter feeding a five-phase biharmonic permanent magnet synchronous machine (PMSM). The algorithm is based on the specific characteristics of multiphase machines, which allows inverter fault detection with sufficient robustness of the algorithm in the presence of fundamental and third harmonic components. First, the inverter fault effects analysis is achieved in the characteristic subspaces of the five-phase PMSM. Specificities that are interesting for the elaboration of a real-time fault detection and identification (FDI) process are highlighted. Original and particular algorithms are used for an accurate 2-D normalized fault vector extraction in a defined fault reference frame. This frame is dedicated only for FDI. To ensure the high immunity of the FDI process against transient states, a particular normalization procedure is applied. The normalized diagnostic signals are formulated from the defined frame and other variables derived from the reference and measured currents. Simulation and experimental results of open-switch and open-phase faults are provided to validate the proposed algorithm.

Fault tolerant dual-motor drives: Sizing of power electronic

This paper analyzes two dual-motor fault-tolerant topologies. The first one supplies independently both machines while the second one connects them in series for reducing the number of transistors. For a given DC-link voltage, the converter component sizing is based on the peak current obtained in the normal and degraded modes.

Optimal efficiency control of synchronous reluctance motors-based ANN considering cross magnetic saturation and iron losses

This paper presents a new method by using the Artificial Neural Networks (ANNs) for estimating the parameters of the machine which achieving the optimal efficiency of the Synchronous Reluctance Motor (SynRM). This model take into consideration the magnetic saturation, cross-coupling and iron losses. With Finite Element Analysis (FEA), the characteristics of the SynRM including inductances and iron loss resistance are determined. Because of the non-linear characteristics, an ANN is trained to obtain the d-q inductances and the iron loss resistance from Id, Iq currents and rotor speed. After learning process, an analytical expression of the optimal currents is given thanks to Lagrange optimization. Therefore, the optimal currents will be obtained online in real time. This method can be achieved with maximum efficiency and high-precision torque control. Simulation and experimental results are presented to confirm the validity of the proposed method.

Dual-Multiphase Motor Drives for Fault-Tolerant Applications: Power Electronic Structures and Control Strategies

This paper analyzes two fault-tolerant dual-multiphase motor drives, a series-connected topology, and a standard H-bridge topology. Previous studies have shown that the series connected topology is appropriate to an aerospace application and has lower peak current in degraded mode in comparison with the H-bridge topology, which may consequently diminish the systems weight and cost. This paper extends the study to compare different control strategies of these structures under two fault conditions: short-circuit of an inverters switch and an open-phase of the machine. The control strategies analyzed in this paper do not impact the fundamental current or the torque generation, but the amplitudes of some harmonics in degraded mode are expected to be narrowed down in order to reduce the inverters size. Some analyses of maximum voltage and peak current in degraded mode have been used for inverter dimensioning. Experimental results are shown and compared to the simulated ones to confirm the validity of this study.