Concentrated Windings in Compact Permanent Magnet Synchronous Generators: Managing Efficiency

Olivier Barré,Bellemain Napame

doi:10.3390/machines4010002

Abstract

In electric power generation, customers want generators with high efficiency. Nowadays, modern turbo-generators have efficiencies greater than 98%. Although this amount should not be obtained for all kind of machines, efficiency will remain one of the main parameters for customer choice. Efficiency is also linked to the life of the machine: the higher the efficiency is, the longer the machine’s lifetime. During the past decade, new forms of energy production have appeared and generators have been developed to fit well into this market. For example, wind generators evolved towards permanent magnet generators having high polarity and running at low speed. Nevertheless, their structure is not fixed. An industrial company has built a prototype of such a generator which uses fractional-slot concentrated-windings (FSCW). This kind of winding is not the structure used by default in such electrical machines. Another field of interest is in autonomous generators which can be used on boats. Even if everyone has in mind large merchant ships, we must not forget smaller ships, such as fishing boats and short-range cruise ships, which spend the most of their time near the coast. This kind of ship does nothave large areas for installing the electric generation or the electric propulsion. It is the reason why, in this article, we focus on the efficiency of machines using fractional-slot concentrated-windings. In many publications which compare performances between distributed and concentrated windings, the result is almost the same. The efficiency of FSCW is not as high as the efficiency associated to the machines which are using distributed windings. Design methods have to be redrawn to integrate, as soon as possible, the loss mitigation in order to provide the best efficiency in power conversion. The following discussion, step by step, introduces the loss mitigation in every part of a machine using FSCW. To close the discussion, a design is produced and it appears that efficiency can be enhanced with suitable design methods.

Highlights

IntroductionPermanent magnet generators are suitable generators where standalone operations are required
Permanent magnet generators are suitable generators where standalone operations are required.their high efficiencies are generally considered as the main advantage
The results deviate from the results presented by I

Summary

Introduction

Permanent magnet generators are suitable generators where standalone operations are required. Their high efficiencies are generally considered as the main advantage. A large number of manufactured machines is using a conventional winding structure: distributed windings. This structure fits well with high-power machines, such as multi-megawatt generators. The distributed winding has its drawbacks, especially in the length of the end windings, which are outside the active part. Fractional-slot concentrated-windings do not have this drawback. The small volume of their end windings allows a short axial length [1]. Fuji Electric, Machines 2016, 4, 2; doi:10.3390/machines4010002 www.mdpi.com/journal/machines

Methods

Results

Conclusion