Pole Arcs Optimization of Vernier Reluctance Motors Supplied with Square Wave Current

International audienceTo maximize their performances, it is profitable to supply vernier reluctance motors (VRMs or Switched Reluctance Motors) with square wave current, but the converter has to switch this current successively into each inductive phase. This raises problems at high speeds. To obtain a high bas speed, therefore a high power, we propose to optimize pole arcs witch have a highly significant importance on the permeance wave of VRMs. The variation range of the angles is restricted by certain conditions, but within these limits optimization is possible. All dimensional parameters were taken into account and used to calculate average torque in linear as well as in saturated mode. We neglected the influence of mutual coupling between phases and this hypothesis was justified by results obtained through measurements. Though we used a model with linearized segments to minimize the number of parameters, the same method can be applied to other more accurate models. A VRM with 6-4 structure was designed and realized; it allowed validation of our theoritical model

Current Feeding of Switched Reluctance Motor. Optimization of the Current Waveform to Minimize the Torque Ripple

International audienceThe torque ripple remains one of the main problem linked to the use of switched reluctance motor. In order to use these drives in low speed application, we have imagined a current control, with optimized waveforms allowing torque ripple minimization. We have take account motor parameters and converter voltage limitations. We applied this control method to a 4kW drive

Torque Ripple Minimisation in Switched Reluctance Motors by Optimisation of Current Wave-Forms and of Teeth Shape with Copper Losses and V.A. Silicon Constraints

International audienceThe main aim of this paper is the minimisation of torque riplle in a 6/4 switched reluctance motor by current waveforms and pole arc optimisation and with realistic constraints. This research is base on a magnetic structure with several sizes which remain constant: outer diameter (250 mm), stack length (150 mm), shaft diameter (42 mm) and airgap length (0.8 mm). Electromagnetic characteristics of 5 machines are computed by element finite method. Before these computations were computed, the main sizes of each machine were optimised by a quick analytical method to minimise copper losses at low speed and with an ideal square wave current supply. Then we determined, for each machine, the optimal current waveforms to minimise ripple torque taking account limit DC voltage

Comparison of Measurement Methods to Determine the Electromagnetic Characteristics of Switched Reluctance Motors

International audienceThree different experimental methods for the electromagnetic characterization of a switched reluctance motor (SRM) are presented in this paper. Two methods rely on static measurements. The first one permits the static torque measurement when one phase of the machine is fed by a direct current. The second one determines the flux characteristic when one phase of the machine is fed at standstill by an alternative current. The third is a flux dynamic characterization method, the SRM is driven at a constant speed and fed by a direct current. Because of the emf of the motor, the feeding current is never perfectly constant especially in the case of medium and high power SRM. A numerical method is then presented which permits to compensate the effects of this current ripple. Finally, the accuracy and the feasibility of the implementation of these methods are compared

Possibilités du moteur à réluctance variable à double saillance pour la motorisation de véhicules électriques. Bilan des essais d'un prototype de 27 kW

National audienceLe moteur à réluctance variable à double saillance (MRVDS) à commutation électronique possède des qualités indéniables en termes d'économie et de robustesse. Ses performances sont comparables à celles des autres moteurs sans balais. Aussi, il a semblé intéressant d'étudier et de réaliser un tel moteur selon le cahier des charges d'un entraînement de véhicule urbain sans boite de vitesses. Dans cette communication, nous rappelons d'abord les grands principes du MRVDS et ses modes d'alimentation puis nous présentons quelques résultats de l'expérimentation d'un moteur capable de délivrer un couple de 110 N.m de 0 à 2500 tr/mn et une puissance maximale de 27 kW de 2500 à 10 000 tr/mn. Une commande en courant optimisé a permis d'atteindre un taux d'ondulation du couple, relativement faible, dans la plage à couple maximal constant. Cependant, le couple reste intrinsèquement très pulsatoire dans la plage des hautes vitesses ce qui peut conduire à une fatigue du réducteur mécanique

Photovoltaic Fault Detection and Diagnosis: Which Level of Granularity for PV Modeling?

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Relationships between HIV disease history and blood HIV-1 DNA load in perinatally infected adolescents and young adults: The ANRS-EP38-IMMIP Study

International audienceBackground: Our aim was to study the impact of lifelong HIV disease history on the current immune and virological status of perinatally infected patients reaching adulthood. We evaluated blood cell-associated HIV DNA load, as an indicator of cell-associated HIV reservoirs and an independent predictor of disease progression.Methods: The ANRS-EP38-IMMIP Study included 93 patients between the ages of 15 and 24 years, who were infected with HIV during the perinatal period. HIV DNA load was quantified by real-time PCR. Results: Eighty-five percent of patients were on HAART, and HIV RNA was undetectable in the plasma of 75% of these patients. The median HIV DNA load was 2.84 (IQR: 2.51-3.16) log10 copies/106 PBMCs. In patients with viral suppression, HIV DNA load was independently associated with cumulative HIV RNA viremia over the last five years. HIV DNA load was negatively correlated with CD4 cell count in patients with active replication but not in those with undetectable HIV RNA. Conclusions: In perinatally infected youths who are successfully treated, sustained viral suppression is associated with low HIV DNA load. The absence of association between current HIV DNA load and CD4 cell counts suggests that the unique physiological characteristics of pediatric infection persist after adolescence