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This paper proposes a strategy using new transformation matrices to calculate new current references when a non-sinusoidal seven-phase permanent magnet synchronous machine (PMSM) has an open-circuited phase. The new current references allow to obtain a smooth torque with similar copper losses in the remaining healthy phases even when the back electromotive force (back-EMF) is non-sinusoidal. A real-time current learning process using an adaptive linear neural network (Adaline) is applied to extract from measured currents useful harmonic components in torque generation. It improves torque quality, especially at high speed, even when standard proportional-integral (PI) controllers are applied. In addition, similar copper losses in the remaining phases with the new current references can avoid overheating of windings. The effectiveness of the proposed control strategy is validated by numerical results. We would like to thank the CE2I project sponsored by European Regional Development Fund, French State, and French Region of Hauts-de-France for the financial support.

International audience; Automotive industry is evolving towards more fault-tolerant actuators to fulfill future autonomous vehicles requirements. Critical applications such as steering or braking have to resist to fault occurrences while being low cost due to mass production market. Considering these two criteria, multiphase electric drives offer a good tradeoff between increasing the degrees of freedom and limiting system oversizing. This paper proposes to compare three multiphase electric drives for electro-hydraulic power steering for trucks: a five-phase machine and a six-phase machine both fed by a full bridge inverter (FBI), and a seven-phase machine fed by a standard half-bridge inverter (HBI). Several comparison criteria are considered in the meantime: motor, electronics, control and manufacturing parameters. Some of criteria are obtained from finite-element analysis (FEA), while others are derived from analytic formula or dynamic simulations . Criteria are evaluated for each drive and then results are discussed. In the given low-voltage high-current application, H-bridge inverter topology seems to be a promising solution. Both five-phase and six-phase present similar results. However, six-phase drive could be more interesting, as it could be brought close to standard three-phase solutions and adapted to dual-lane supply.

International audience; Automotive safety applications will be soon a standard based on market evolution trends. Actuators performing safety operations, such as steering or braking, need to be more reliable with a low manufacturing cost. Multiphase drives seem to be a good alternative to actuators redundancy, as it offers greater degrees of freedom with at a limited extra cost. These drives have been studied for a while, especially in other industries such as ship propulsion or aeronautic actuator. However, comparison between multiphase drives for a given application is rare. In this paper, a methodology is proposed to evaluate several drives for a safety automotive application. Some manufacturing assumptions have been made in order to narrow the study to five, six and seven phase permanent magnet synchronous motors (PMSM). Machines have been modeled using 2-D finite elements analysis (FEA) software in order to extract their parameters which will be used in dynamic simulations. Based on the obtained results, each drive is evaluated according to defined criteria and best solutions are highlighted. Considering a low voltage high current application, full bridge inverter topologies feeding a six-phase motor seem to be a promising solution.

Multiphase permanent magnet synchronous machines (PMSMs) have started to be used more and more in the electrification of transportation systems. These systems have several specific requirements such as: high efficiency, high power density, high functional reliability, robustness, and compactness (easier for integration). Basically, to perform the vector control of multiphase PMSM drives, the essential information of the rotor position and speed is obtained by a position sensor mounted at the end of the rotor shaft. In the context of high functional reliability and compactness, the replacement of the position sensor by a “soft” position sensor, using only electrical sensors (currents) is interesting. This replacement helps to avoid the sensitivity of the position sensor to the environment and the necessity of an available rotor shaft end. Therefore, the purpose of this doctoral thesis is to perform accurate sensorless control algorithms for multiphase PMSM drives with the aim of enhancing their reliability and compactness. In this thesis, an algorithm based on the sliding mode observer is proposed to estimate the rotor position and speed by using the estimated back-electromotive forces of all fictitious machines of multiphase PMSM. To solve the problem of PMSM observability at standstill and low speed ranges, an algorithm based on the high-frequency signal injection and specificities of multiphase machines is developed. These algorithms guarantee the precise sensorless control of multiphase PMSM drives in all speed ranges. Experimental results of a non-sinusoidal seven-phase PMSM are given to verify the effectiveness of the proposed sensorless control algorithms in healthy and degraded mode.; L’électrification des systèmes de transport nécessite l’émergence d’entrainements électriques qui répondent à certaines exigences en termes de : rendement et densité de puissance élevés, fiabilité fonctionnelle, robustesse et compacité (facilité d’intégration). Dans ce contexte, les machines synchrones à aimants permanents (MSAP) polyphasées (nombre de phases > 3 ) sont devenues de plus en plus étudiées en raison de leurs densités énergétiques volumique et massique élevées, et leurs tolérances aux défaillances. Pour assurer un contrôle vectoriel performant de ces machines, un capteur de position mécanique est monté sur l’arbre de la machine pour fournir l’information de la position et de la vitesse du rotor. Cependant, dans un contexte de fiabilité fonctionnelle et de robustesse des machines MSAP polyphasées, un défaut sur ce capteur de position ou sur l’une de ses connexions entraine directement une défaillance du système de contrôle. Par ailleurs, dans un contexte de compacité, la nécessité d’un bout d’arbre pour monter ce capteur, qui lui aussi occupe du volume, entraine une augmentation du volume global des entrainements polyphasés. L’objectif de la thèse est de développer des algorithmes spécifiques à la commande sans capteur de machines MSAP polyphasées à force électromotrices non-sinusoïdales dans le but d’augmenter leurs fiabilités fonctionnelles et leurs compacités. Pour cela, des algorithmes basés sur le principe de l’observateur à mode glissant sont développés pour estimer la position et la vitesse du rotor à partir de l’estimation des forces électromotrices des différentes machines fictives équivalentes. Pour résoudre le problème d’observabilité des machines MSAP à zéro et faible vitesse, des algorithmes de commande sans capteur basés sur l’injection d’une tension sinusoïdale à haute fréquence dans la machine fictive qui contribue faiblement à la production du couple sont développés. L’obtention de la position sur toute la plage de vitesse des machines MSAP polyphasées en mode normal et dégradé peut ainsi être obtenue. Les différents algorithmes proposés dans ces travaux de thèse sont validés expérimentalement sur une machine MSAP à 7 phases à forces électromotrices non-sinusoïdales.

This two-part study proposes a new sensorless control strategy for non-sinusoidal multiphase permanent magnet synchronous machines (PMSMs), especially integrated motor drives (IMDs). Based on the Sliding Mode Observer (SMO), the proposed sensorless control strategy uses the signals (currents and voltages) of all fictitious machines of the multiphase PMSMs. It can estimate the high-accuracy rotor positions that are required in vector control. This proposed strategy is compared to the conventional sensorless control strategy that applies only current and voltage signals of the main fictitious machine, including the fundamental component of back electromotive force (back EMF) of non-sinusoidal multiphase PMSMs. Therefore, in order to choose an appropriate sensorless control strategy for the non-sinusoidal multiphase PMSMs, these two sensorless control strategies will be highlighted in terms of precision with respect to rotor position and speed estimation. Simulations and the experimental results obtained with a non-sinusoidal seven-phase PMSM will be shown to verify and compare the two sensorless control strategies. In this part of the study (part I), only sensorless control in the medium and high-speed range is considered. Sensorless control at the zero and low-speed range will be treated in the second part of this study (part II). Financement par le Projet C2EI - Hauts de France

This study investigates a real-time fault diagnostic of a transportation system which needs two drives with fault-tolerance capabilities. Owing to the constraints on the mass of the system and on the cost of the voltage source inverter, a drive with two six-phase permanent magnet synchronous machines in series-connection supplied by two six-leg inverters is chosen. Despite the serial connection, independent control of the two machines and fault-tolerance to open-switch fault is ensured. Nevertheless, a fault detection identification (FDI) process is required for analysis and/or control reconfiguration. The proposed FDI is based on the combination of different criteria obtained from the two zero-sequence currents and from the normalised currents mapped into two frames defined by the concordia transformation. Results obtained from simulation and experimental tests show the effectiveness of the proposal.

For non-sinusoidal electromotive force (NS-EMF) multiphase machines, this paper proposes a new strategy and control scheme to guarantee smooth torque under an open-phase fault. Notably, the conventional proportional-integral (PI) controllers implemented for vector control in healthy mode can be used in the faulty mode. The strategy is based on reduced-order transformations while the control scheme applies a simple artificial intelligence algorithm using a specific online-trained Adaptive Linear Neuron (ADALINE). Indeed, the inputs of ADALINE require the knowledge of rotor position and NS-EMF harmonic rank to optimize the learning time. The proposed strategy and control scheme are tested on a seven-phase machine with a strong Total Harmonic Distortion (THD) of NS-EMFs, containing numerous harmonics Hk (THD=38% with 100% H1, 32.3% H3, 9.4% H7, 12.5% H9, 10.3% H11). Numerical and experimental results are presented in this paper. This paper is accompanied by a video demonstrating the experimental results. This research was funded by CE2I project. CE2I is co-financed by European Union with 573 the financial support of European Regional Development Fund (ERDF), French State and the French 574 Region of Hauts-de-France.

International audience; This paper proposes a sensorless control strategy based on Sliding Mode Observer (SMO) for a Five-phase Interior Permanent Magnet Synchronous Machine (FIPMSM), with a consideration of the third harmonic component. Compared to conventional three-phase machines, the third harmonic of back electromotive force (back-EMF) contains more information. Thus, in this paper, the first and third harmonic components of the five-phase machine are considered to estimate the rotor position which is necessary for the vector control. Simulation results are shown to verify the feasibility and the robustness of the proposedsensorless control strategy.

This paper is to propose a control scheme, a combination of the classical field-oriented control (FOC) technique and artificial intelligence (AI), to obtain constant torques in multiphase non-sinusoidal permanent magnet synchronous machine (PMSM) drives. Higher torque density, easier fabrication, and lower costs are several advantages of non-sinusoidal back electromotive force (back-EMF) machines over sinusoidal ones. However, multi-harmonics existing in back-EMFs possibly generate torque ripples, reducing torque quality of the drive. Therefore, in this paper, an adaptive linear neuron (ADALINE), a simple type of AI, is combined with the classical FOC technique to eliminate these torque ripples. The proposed control scheme is validated by numerical results with a seven-phase PMSM. In addition, these results are compared with an existing strategy to prove its effectiveness. This work has been achieved within the framework of CE2I project. CE2I is co-financed by European Union with the financial support of European Regional Development Fund (ERDF), French State and the French Region of Hautsde- France.

In the context of future Permanent Magnet Synchronous Machines (PMSMs) with a high number of phases (>7) in integrated drives, this paper proposes several control strategies when multiphase PMSMs with non-sinusoidal back electromotive forces (back-EMFs) operate in healthy and open-circuit faults. In all operation modes, the considered constraint on current is related to the maximum root mean square (RMS) current allowable in one phase of the machine. The constraint on voltage limits the maximum peak value of the phase voltage determined by the DC-bus voltage of the converter. When one or two phases are open-circuited, to maximize torque and respect the constraints, new current references obtained by several proposed methods in rotating and natural frames are imposed to the machine. Due to the non-sinusoidal waveform of back-EMFs and the considered constraints, numerical computations based on analytical formulations are required to obtain maximal torque-speed characteristics, including the flux-weakening operation. The usefulness of the proposed strategies is verified by numerical and experimental results. This work has been achieved within the framework of CE2I project. CE2I is co-financed by European Union with the financial support of European Regional Development Fund (ERDF), FrenchState and the French Region of Hauts-de- France