Compact electrical generators for diesel driven generating sets

Abstract

This thesis explores two approaches for converting rotating mechanical power from diesel engines into electrical power of fixed frequency and voltage. Advances in high energy permanent magnets and power electronics are enabling technologies that provide opportunities for electrical machines with increased efficiency and compact size. Two approaches are explored, Variable Speed and Fixed Speed power generation. For variable speed, the concept of Variable Speed Integrated Generating Sets (VSIGs) are discussed and suitable electrical machine types reviewed. Axial and Radial permanent magnet machines are compared in detail. An axial flux machine often referred to as the TORUS is researched, and a 50 kW unit designed to integrate within the flywheel housing of a diesel engine. Manufacturing aspects are considered, and two prototype machines are built and tested, the second machine demonstrates a rating of 60kW at 3000rpm. A machine model based upon a combination of Finite Element Analysis and polynomial curve fitting is developed to provide an insight into the design of such machines. During the course of this research a new form of axial electrical machine known as the Haydock Brown Machine was invented. The fundamental problem of regulating the output voltage for permanent machines has been over come by the addition of an excitation coil. Saturation, significant leakage fields and three excitation sources make the electromagnetic design process for the Haydock Brown Machine complex. The intuitive application of an equivalent circuit model provides satisfactory results and a 10kW prototype machine operating at fixed speed is built and tested. Using the model new observations are made and a new improved version is proposed called the Haydock Brown Hybrid Machine.