Slot/pole Combinations Choice for Concentrated Multiphase Machines dedicated to Mild-Hybrid Applications

Version de l'éditeur à l'adresse suivante : http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6119910&isnumber=6119266This paper presents multiphase permanent magnet machines with concentrated non-overlapped winding as a good candidate for automotive low voltage mild-hybrid applications. These machines often require a trade-off between low speed performances such as high torque density and high speed performances like flux weakening capabilities. This paper describes how to choose a key design parameter to ease this compromise, the slots/poles combination, according to three parameters: winding factor including harmonics factor, rotor losses amount thanks to a comparison factor and radial forces balancing. The comparison criterion are based on both analytical formula and Finite Element Analysis.Projet MHYGALE/ ADEM

Analytical Optimal Currents for Multiphase PMSMs Under Fault Conditions and Saturation

An original analytical expression is presented in this paper to obtain optimal currents minimizing the copper losses of a multi-phase Permanent Magnet Synchronous Motor (PMSM) under fault conditions. Based on the existing solutions [i]opt1 (without zero sequence of current constraint) and [i]opt2 (with zero sequence constraint), this new expression of currents [i]opt3 is obtained by means of a geometrical representation and can be applied to open-circuit, defect of current regulation, current saturation and machine phase short-circuit fault. Simulation results are presented to validate the proposed approach

Enhanced Torque Control of a PMSM Supplied by a Four-Leg Voltage Source Inverter Using the Third Harmonic

This paper investigates an electrical drive composed of a four-leg voltage source inverter and a three-phase starconnected surface permanent magnet synchronous machine with concentrated windings. The inverter fourth leg is clamped to the neutral point of the machine. We find the current references leading to smooth torque and maximal torque per ampere operation in the presence of a third harmonic electromotive force component. We further analyze the advantages of the proposed topology in terms of torque increase and dc-link voltage requirements

High Order Sliding mode optimal current control of Five Phase Permanent magnet Motor under Open Circuited phase Fault Conditions

Electrical marine propulsion systems are characterized by very high level requirements in terms of compactness, acoustic behavior and reliability. In this particular context, the use of multiphase PM machines associated with VSI drives appears to be a very efficient solution. Presented work focus on the use of such a system in open circuited phase fault conditions. With this kind of system it is possible to determine optimal current references which maximize the torque density of the system when one or two phases are open circuited. Classical linear controllers (as PID for example) cannot provide a correct tracking of these optimal current references because they have a highly dynamical behavior. We propose in this paper to combine this optimal current reference generation with High Order Sliding Mode (HOSM) control. This kind of solution allows a good tracking of these unconventional current references with a fixed switching frequency for the VSI. This method is validated experimentally using a low power experimental set-up which associates a 5-phase PM machine with a DSP controlled IGBT 5-leg VSI drive

Commande avec prise en compte de défauts d’ouverture de phase d’une machine pentaphasée à aimants associée à un onduleur de tension MLI

Cet article est consacré à l’étude d’une méthode de commande d’une machine synchrone à aimant permanent à cinq phases associée à un onduleur de tension à MLI intersective. On s’intéresse au cas de la commande en mode normal et en mode dégradé. Les défauts étudiés sont liés à la déconnexion d’une phase ou de plusieurs phases. Dans ce cas la méthode étudiée, qui est basée sur une approche vectorielle, permet une détermination en ligne des courants de référence optimaux adaptés au défaut. De ce fait, cette méthode garantit un fonctionnement continu de la machine. L’approche de commande utilisée est basée sur le formalisme multimachine des machines polyphasées. Le contrôle des courants utilise des régulateurs PID qui seront comparés des régulateurs type hystérésis en mode normal et en mode de défaut. Les résultats de simulation effectués sur MATLAB / Simulink sont présentés et discutés afin de vérifier les performances de la stratégie et des régulateur étudiés. Ils montrent en particulier l'efficacité de la régulation de type PID en mode normal et de la régulation par hystérésis en mode de défau

Fault Tolerant 7-phase Hybrid Excitation Permanent Magnet Machine

This paper presents a novel 7-phase hybrid excitation permanent magnet (HEPM) machine with three rotors around one stator. Two rotors with PMs axially magnetized and the third rotor with PMs radially magnetized. Thanks to the addition of the third rotor, the inactive end-windings in the configuration with two rotors are then becoming active with a contribution to the torque with an increase of 30%. The impact of the third rotor on the torque density and on the pulsating torques is presented. The fault-tolerant characteristics of the proposed machine are also presented, which proves the interests of this machine for low speed applications

High Order Sliding mode optimal current control of Five Phase Permanent magnet Motor under Open Circuited phase Fault Conditions

Electrical marine propulsion systems are characterized by very high level requirements in terms of compactness, acoustic behavior and reliability. In this particular context, the use of multiphase PM machines associated with VSI drives appears to be a very efficient solution. Presented work focus on the use of such a system in open circuited phase fault conditions. With this kind of system it is possible to determine optimal current references which maximize the torque density of the system when one or two phases are open circuited. Classical linear controllers (as PID for example) cannot provide a correct tracking of these optimal current references because they have a highly dynamical behavior. We propose in this paper to combine this optimal current reference generation with High Order Sliding Mode (HOSM) control. This kind of solution allows a good tracking of these unconventional current references with a fixed switching frequency for the VSI. This method is validated experimentally using a low power experimental set-up which associates a 5-phase PM machine with a DSP controlled IGBT 5-leg VSI drive

A novel Sensorless Control Strategy Based on Sliding Mode Observer for Non-Sinusoidal Seven-phase PMSM

This paper proposes a new sensorless control strategy based on a Sliding Mode Observer (SMO) for a non-sinusoidal seven phase PMSMs. This strategy, based on all harmonics contained in the back-EMF, is compared to the classical sensorless control strategy using only the fundamental of back-EMF signal. As the novel sensorless control strategy estimate the rotor position by using different harmonics, it can lead to a good torque response compared to the classical strategy, specially in transient states. Therefore, in order to define the appropriate sensorless control strategy for the non-sinusoidal seven-phase PMSM, each sensorless control strategy will be highlighted in terms of robustness to the speed variation and torque ripple. Simulation results will be shown to verify the feasibility of the proposed methods.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 Hauts-de-France

Sensitivity of Torque Control for Seven-phase BLDC Machine with One Opened Phase under Constraints on Voltage and Current

This paper deals with control strategies when a sevenphase axial-flux brushless DC machine operates in one opencircuited phase fault by considering constraints on voltage and current. The constraints are related to the converter and machine design in terms of peak values of non-sinusoidal voltage and current. In addition, the sensitivity of the torque control on parameters of new imposed current references under the base speed and in the flux-weakening region is analyzed. The current references taking into account only first and third harmonics in healthy phases are proposed to ensure the torque optimization while phase currents and voltages are within their limits. The usefulness of the control strategies and the parameter analyses are verified by numerical results

Torque Optimization of a Seven-Phase Bi-harmonic PMSM in Healthy and Degraded Mode

Compared to sinusoidal machines, a bi-harmonic machine (with only two harmonics of similar value in the electromotive force spectrum) can develop torque of comparable values under three kinds of supply: with only first or both first and third sinusoidal currents. Therefore, more degrees of freedom for the control of the machine can be achieved. In this paper, the specificities of a 7-phase bi-harmonic permanent magnet synchronous machine (PMSM) are investigated under different control strategies, such as maximum torque per ampere (MTPA) at low speed and fluxweakening strategies at high speed, both in healthy and faulty operation modes. The fault with one open-circuited phase are taken into account. The current references are calculated in order to maximize the output torque under the constraint on both voltage and current. The performances of the considered machine is validated by numerical results