High Voltage Direct Drive Generators with Multiphase Single Layer Fractional Slot Concentrated Windings

Paper in proceeding, 2020

This paper presents design considerations for a high voltage direct drive generator for an high voltage DC offshore wind park application. The paper investigates 3-phase and 6-phase fractional slot concentrated windings for high voltage surface mounted permanent magnet machines. The paper focuses on q=2 /5, 50 pole-pairs and q=4 /11, 55 pole-pairs machines in the single layer configuration with different number of phases. The analysis has been executed by both analytical and finite element analysis methods. The paper reports the results of the comparison in terms of torque performance, power factor and losses, aiming to demonstrate the advantages and limitations of the use of fractional slot concentrated windings single layer multiphase generators for high voltage wind turbines. It is found that single layer multiphase configurations can improve the performance of the generator in terms of torque density, torque ripple and efficiency, but the low power factor can be a limiting factor for the exploitation of this technology for high voltage high power generators for wind turbine applications. In this paper, a solution to improve the PF without sacrificing the efficiency is proposed.