Abstract
This work is focused on the design optimization of electrical machines that are used in small-scale direct-drive aerogenerators. A ducted wind turbine, equipped with a diffuser, is considered due to its enhanced power capability with respect to bare turbines. An annular type Permanent Magnet brushless generator is integrated in the turbine structure: the stator coils are placed in the internal part of the diffuser, whereas the permanent magnets are on an external ring connected to the turbine blade tips. Moreover, as regards the stator windings, the Printed Circuit Board (PCB) technology is investigated in order to exploit its advantages with respect to conventional wire coils, such as the increased current density capacity, the reduction of costs, and the enhanced precision and repeatability of the PCBs. An original design procedure is presented together with some scalability rules. An automated tool has been developed in order to aid the electrical machine designer in the first design stages: the tool performs multi-objective optimizations (using the Matlab Genetic Algorithm Toolbox), coupled to fast Finite Element analysis (through the open-source software FEMM) for the evaluation of the electromagnetic torque and field distribution. The proposed procedure is applied to the design of an annular PM generator directly coupled to a small-scale turbine for an urban application.
Highlights
The development of renewable power generation systems is getting even more important in the last decades due to the increasing demand of electrical power and the increased attention towards the reduction of CO emissions [1]
The tool allows the design of annular type Permanent Magnet (PM) machines with inner rotor and concentrated windings on the stator core made by Printed Circuit Boards (PCB); the authors are currently working towards its extension to different machines topologies and PM arrangements
An automated tool that is based on genetic algorithms and fast finite direct-drive ducted wind turbines
Summary
The development of renewable power generation systems is getting even more important in the last decades due to the increasing demand of electrical power and the increased attention towards the reduction of CO emissions [1]. Different one-dimensional (1D) theoretical models have been proposed in the literature in to consider ducted wind turbines, a reformulation of the conventional element orderIntoorder predict the power production of wind turbines, with particular reference toblade shrouded or momentum theory was proposed in [28] In this case, CFD simulations have been carried out diffuser-augmented ones [4,24,25,26,27]. The turbine effect on the flow field has been accounted for, the disc reduces the wind speed from va upstream to vp at the rotor and to vO by means of source terms forthe thepressure momentum solved section inside the domain byhas thearotor; downstream; risesequations at the upstream of the rotor,swept it drop this allows forand avoiding meshdownstream refinement [27].
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