Search results for "Electrical machine"
showing 10 items of 11 documents
An Experimental Comparison between an Ironless and a Traditional Permanent Magnet Linear Generator for Wave Energy Conversion
2022
Permanent Magnet Linear Generators (PMLGs) are currently being studied for sea wave energy harvesting. Typically, a PMLG consists of an iron-made armature and a moving translator. The permanent magnets adoption produces parasitic effects, such as cogging force, and the machine weight increment. A solution could be the adoption of an ironless configuration, accepting a power density reduction. This paper investigates the use of ironless PMLGs in sea wave energy conversion systems by an experimental comparative analysis between an iron PMLG prototype and an ironless PMLG prototype, which share the same geometry. The main electrical and mechanical parameters (resistance, mass, and magnetic fie…
Fast procedure for the calculation of maximum slot filling factors in electrical machines
2017
This paper presents an algorithm for the calculation of maximum slot filling factor in electrical machines. The determination of whole wire cross section that occupy the area of a stator slot is very important in order to estimate the copper losses: The greater is the filling factor the lower are copper losses. The main goal of this paper is to define a simple algorithm for the determination of slot filling factors suitable for all type of slot profiles. The algorithm can be considered as an additional useful tool for the fast design of electrical machine windings.
Reduction of cogging force in linear generators for wave energy harvesting
2022
Due to huge energy potential of sea waves, many technologies have been proposed in the last few years. Some concepts have been developed and sometimes also tested in the open sea. Some prototypes use linear generators to directly convert the vertical motion of buoys into electrical energy. This solution minimizes the numbers of energy conversion steps, increasing the energy efficiency. At the same time, the limited numbers of components could also increase the reliability of the wave energy converter. For this reason, the development of linear generators is considered with great interest. This paper investigated the cogging force, a magnetic force due to the interaction between the magnets …
Differential Leakage Factor in Electrical Machines Equipped with Asymmetrical Multiphase Windings: a General Investigation
2019
This paper presents an investigation in terms of degree of unbalance and leakage factor of electrical machines equipped with multiphase windings. The analysis has been carried out through 4800 combinations between slots/poles/phases/layers, analyzing the variability of the leakage factor for each condition and determining the optimal region for its minimization. The obtained results demonstrate that the leakage factor could be considerably reduced with the adoption of slightly asymmetrical windings, which represent a favorable option during the early design stage of electrical machines.
A new solution for the sea wave exploitation. A linear ironless generator
2019
The exploitation of sea wave represents an important frontier for the energy sustainability in the next future. Despite the proposal of several techniques and solutions, commercial devices are not available. In this context, the Department of Engineering is investigating an innovative solution based on linear energy generators. This machine can be adopted as the main component in a wave energy converter, that is the device for the energy extraction of sea wave. Starting from an existing prototype, the paper examines the replacement of the iron stator with a non-magnetic material, in order to solve several common problems of linear generators, such as the cogging force. Results are reported,…
Design and Experimental Test of a Thermomagnetic Motor
2012
Abstract This paper presents a Thermomagnetic Motor. The design of the motor is based on a thermal-magnetic coupled dynamic model, which is obtained by assuming the use of a ferromagnetic material working at temperatures near the curie point. The motor is modeled in terms of both its magnetic as well thermal properties (magnetic permeability and thermal conductivity) and the thermal processes are supposed to be influenced by the thermal conductivity, the convection and the advection. An analytical expression of the generated torque, which links this quantity to the magnetic, thermal and geometrical parameters of the generated torque is given. A design of a machine, based on this theory is p…
A general procedure for the construction of Gorges polygons for multi-phase windings of electrical machines
2018
This paper presents a simple and effective procedure for the determination of the Gorges polygon, suitable for all possible winding configurations in electrical machines. This methodology takes into account the determination of a Winding Distribution Table (WDT), in which all the information about the distribution of the currents along the stator periphery is computed and from which the Görges polygon are easily derived. The proposed method can be applied to both symmetrical and asymmetrical multi-phase windings, including concentrated, fractional, reduced and dead-coil ones. The examples provided in this paper demonstrate the versatility of the proposed method.
A General Mathematical Formulation for Winding Layout Arrangement of Electrical Machines
2018
Winding design methods have been a subject of research for many years of the past century. Many methods have been developed, each one characterized by some advantages and drawbacks. Nowadays, the star of slots is the most widespread design tool for electrical machine windings. In this context, this paper presents a simple and effective procedure to determine the distribution of the slot EMFs over the phases and of the winding configuration in all possible typologies of electrical machines equipped with symmetrical windings. The result of this procedure gives a Winding Distribution Table (WDT), which can be used to define coils and coil groups connections and also to simply implement winding…
A General Investigation on the Differential Leakage Factor for Symmetrical and Asymmetrical Multiphase Winding Design
2020
This work provides an investigation based on a fast estimation of the degree of unbalance (D.U.%) and the differential leakage factor (&sigma
Design Considerations of Transverse Flux Generator to Sea Wave Energy
2014
In this paper we study the possibility to use a transverse flux linear generator (TFG) because transverse flux technology presents the highest force density per volume index among the iron based electrical machines. This paper is organized as follows an introduction to describe "state of the art" of WEC's and TFG, in the Section II we find a summary description of the marine condition of the chosen site; in the Section III there is an the analytical procedure for geometric and magnetic design of device (chosen material, length, etc) and in the Section IV the simulation of generator. Further defined the design of the generator, the machine was designed and analyzed through the use of a 3D FE…