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A new axial-field synchronous machine designed for a flywheel accumulator is presented herein. The armature and field windings, fixed in the air gap, are made with double-face printed circuits. A specific armature layout provides a sine-distributed magnetomotive force and solves the problem of crossing the ends of the winding. A two-dimensional semi-analytical model at the mean radius, using surfacic permeances, is then developed. Then, inductances, torque, and eddy-current losses are calculated using this model and compared with experimental results. Index Terms--Axial-field synchronous machine, double-face printed winding, flywheel accumulator, surfacic permeance.

In this paper, a new multi-rod linear actuator is presented. This actuator has been developed for high thrust density and wide mechanical bandpass applications. The multi-air-gap concept will first be illustrated and explained. Its advantages will be highlighted thanks to finite-element method optimizations. Next, the multi-rod prototype technology will be discussed. Lastly, experimental measurements for prototype forces will be provided. Index Terms--High mechanical bandpass, linear permanent-magnet motor.

A sensitivity analysis is carried out on the parameters of a photovoltaic water pumping system (PVWPS) for domestic water supply in rural areas. The results show that the photovoltaic modules peak power, the motor-pump efficiency, and the water tank volume strongly influence the system performance. This highlights that these parameters constitute judicious optimization variables. Besides, the cost of the motor-pump, the cost of the water tank, and the lifetime of the PVWPS have the largest impact on the system cost. These six parameters are therefore of primary importance for the technoeconomic optimal sizing of the system. Finally, it is shown that the hydraulic losses play a minor role and that it is not necessary to consider the evolution of the ambient temperature when modeling PVWPS for domestic water supply. This study can be useful to nongovernmental organizations, companies, and governments which install PVWPS for domestic water access. It can help them to determine the accuracy at which a given parameter has to be known to correctly model or size these systems. Besides, it can allow them to evaluate the robustness of PVWPS sizing to parameters variation with time and may guide their choice of components. [ABSTRACT FROM AUTHOR]

This paper focuses on a two-dimensional (2-D) analytical model for a fast computation of magnetic losses due to eddy currents in the permanent magnets as well as iron losses in the ferromagnetic parts within coaxial magnetic gears. The magnetic field distribution is computed in yokes and permanent magnets by solving both Maxwell's equations, whereas for pole pieces, the magnetic field is computed by coupling the previous analytical model with a reluctance network model. Both the eddy current losses and iron losses are determined from this hybrid analytical model. The iron loss model takes into account the temporal and spatial variations of flux density. The eddy current loss model takes into account the magnet splitting. Results of this magnetostatic eddy current loss model are then compared to the results obtained with a 2-D magnetodynamic finite element model. A verification of validity limits is also proposed. The final function of this analytical model is to ensure integration into a set of models in the aim of a global mechatronic optimization of magnetic gears, for their insertion into multimegawatt wind turbines. A preliminary bi-objective, mass-efficiency optimization protocol is subsequently proposed along with an analysis of the computation time reduction via the presented models. [ABSTRACT FROM AUTHOR]

A solar-powered switch reluctance motor drive using photovoltaic transistors (PVTs) is presented. The expression “PVT” is used to designate a conventional photovoltaic (PV) cell used as a light-controlled power transistor. To obtain a motor drive, a set of PVTs controls the current fed from an external dc power source to the motor phases. The control is achieved by modulating the sunlight hitting the PVTs using a shutter driven by the motor rotor. If the external dc source is a solar panel, the resulting system is able to convert light energy into mechanical energy, without the need of any brushes or other power electronics components. This system could be more affordable and reliable than conventional ones, and therefore, is well suited for off-grid applications like water pumping. This paper first discusses the operation of a PVT through the proposition and the validation of a model. Then, the operating principle of a PVT inverter is clarified. Finally, experimental and numerical results on the first PVT inverter-fed switched reluctance motor are reported. A prototype was built using a switched reluctance motor 6/4 and 12 PVTs. It was here connected to an external 12 V dc power source as a step before using a solar PV source. Results that the PVT inverter-fed switched reluctance motor was operating as expected and provided useful power. [ABSTRACT FROM AUTHOR]

This paper focuses on the computation time and precision of a linear 2-D magnetic gear analytical model. Two main models of magnetic gears are studied: 1) the first with an infinite relative permeability of yokes and 2) the second with a finite relative permeability of yokes. These models are based on the subdomain resolution of Laplace and Poisson equations. To accurately compute the magnetic field distribution, it is necessary to take into account certain harmonics of the various rings and other system harmonics due to modulation. Global system harmonics, which increase the value of computation time, must also be taken into account. If the magnetic gear has a high pole number, then computation time increases even more and no longer allows for system optimization. This paper proposes to compute magnetic field distribution using different harmonic selection methods in order to significantly reduce the computation time for the magnetic torque without any loss of accuracy. [ABSTRACT FROM AUTHOR]

This paper compares the sizing of distributed energy storage systems (ESS) with two control types in order to smooth a direct wave energy converter farm production, namely a centralized one that deals with the point of common coupling (PCC) power with aggregated information and a decentralized one that deals with each unit with only local information. The main objective is to compare the two controls on the basis of their life cycle cost. The ESS is necessary for grid integration in the case considered here due to the flicker constraint. The co-optimization strategies for both the sizing and the management of an ESS are based on a rule-based energy management and a sequential approach to deal with the power quality constraint. This management strategy has been optimized for each size in order to reduce aging speed while respecting the flicker criterion. The final design is expected to minimize total system cost. The centralized control clearly allowed smaller capacity. However, it may lead to an increase in cables losses compared with the decentralized case, although it is expected to be negligible under the conditions considered in this paper. The confirmation of this hypothesis will be the objective of future work. [ABSTRACT FROM PUBLISHER]

We usually find applications of rotary induction generator, direct-drive tubular linear permanent-magnet generator, etc. for the mechanoelectrical conversion process within Stirling microcogenerator systems. This paper presents the design optimization investigation for a direct-drive tubular linear induction generator for a dual free-piston Stirling microcogenerator system. On the one hand, a high oscillating frequency and a relatively long piston's travel bring about a very high acceleration of the generator's moving part, up to 1018 m/s 2. On the other hand, the tubular linear induction generator offers many interesting assets in this application: low weight mover, appearance of levitation force, no mechanical spring, low mechanical losses, no cogging force, easy manufacture, very low investment and maintenance cost, and so on. However, the tubular linear induction generator is sparsely used, because of its a priori relatively low energetic efficiency. This paper presents a sizing optimization approach for maximizing the performance and demonstrates that, with an astute arrangement of electrical devices, the tubular linear induction generator can constitute a well adapted solution for free-piston Stirling microcogenerator systems. [ABSTRACT FROM PUBLISHER]

This paper proposes an original model for supercapacitors that takes into account both calendar aging and cycling aging. A state variable is used to quantify the state of aging. This model is based on a series of recent experiments conducted in various research laboratories on the same technology (Maxwell Technology) and serves to represent the degradation of equivalent series resistance and capacitance. This model is particularly useful in an aging-aware life-cycle cost analysis. We show that an accurate aging model is critical to the design of an energy storage system that optimizes the economic life-cycle cost. Such an optimization is particularly applicable for smoothing in offshore systems such as direct wave energy converters, which require both cost reduction and high reliability. The influence of an aging model in the sizing process is investigated toward the end of this paper. [ABSTRACT FROM AUTHOR]

ABSTRACT The availability of day-ahead production forecast is an important step toward better dispatchability of wind power production. However, the stochastic nature of forecast errors prevents a wind farm operator from holding a firm production commitment. In order to mitigate the deviation from the commitment, an energy storage system connected to the wind farm is considered. One statistical characteristic of day-ahead forecast errors has a major impact on storage performance: errors are significantly correlated along several hours. We thus use a data-fitted autoregressive model that captures this correlation to quantify the impact of correlation on storage sizing. With a Monte Carlo approach, we study the behavior and the performance of an energy storage system using the autoregressive model as an input. The ability of the storage system to meet a production commitment is statistically assessed for a range of capacities, using a mean absolute deviation criterion. By parametrically varying the correlation level, we show that disregarding correlation can lead to an underestimation of a storage capacity by an order of magnitude. Finally, we compare the results obtained from the model and from field data to validate the model. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper sets forth a sizing optimization methodology of a surface permanent magnet machine-converter system over a torque-speed operating profile. The two optimization objectives are to minimize the cost of the machine-converter system and to minimize (or maximize) electrical energy consumption (or generation). The optimization parameters serve to describe both the machine geometry and the electrical ratings of the electronic power converter. Each operating point of the profile is treated independently, and current control is optimized at every operating point to not only minimize machine drive losses but also satisfy several constraints and then implicitly considering flux-weakening possibility. This optimization methodology is generic and is applied to a particular case: a direct-drive conversion chain for a wave energy converter (WEC). We show that taking into account both the sizing parameters of the converter and the flux-weakening control, in addition to the classical sizing parameters of the machine, has a strong impact on the machine-converter system optimal results. Moreover, the strong coupling with the WEC through damping parameters plays also a crucial role on the sizing results. [ABSTRACT FROM PUBLISHER]

This paper will begin by presenting two power takeoff (PTO) technologies for the SEAREV wave energy converter (WEC) followed by the design methodology applied to electromagnetic generator cycles for the all-electric solution. The operating principle associated with the SEAREV WEC will be described before discussing the two conversion technologies intended to transform wave energy into electricity. The types of systems are twofold: hydroelectric and all-electric. The strong coupling between the hydrodynamic, mechanical, and electrical phenomena heavily influences the behavior of the recovery (PTO) system and leads to a complex system design that requires a full-scale modeling description. A unique design methodology for the all-electric conversion chain has been developed around several distinct control modes, including one featuring power leveling. [ABSTRACT FROM AUTHOR]