Exterior rotor permanent magnet generator in variable speed applications

This thesis explores approaches for converting rotational 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 for variable speed power generation. The overall objective was to design a permanent magnet machine with concentrated winding that could be used in variable speed application. Specifically, the aim is to extract the maximum power density and torque by utilizing high pole numbers and minimizing magnetic material content. The concept of variable speed is discussed and suitable electrical machines are reviewed. A radial flux Permanent magnet machine is researched and possible integration methodologies explored within the flywheel housing of the diesel engine. A machine design model is developed based upon a combination of analytical and finite element analysis tools and explore an insight into the design of such machines and optimisation of the overall performances, leading to smaller size, less maintenance, smaller carbon foot print and higher speed. To take into account the thermal aspects of the design, a basic thermal model was developed to understand the influence of the temperature on the overall performance of the design along with the temperature of the windings and magnets. A number of scientific contributions were generated from the analysis of the above objectives, they are as follows; The concept of the variable speed application and its benefits over fixed speed generation Design and analysis of a suitable configuration of the PM machine for a variable speed application Integration methodology of PM machine into the flywheel of a diesel engine Identified power conditioning system topologies which could be applied in variable speed application Briefly, explored the selection methodology for engines for fuel reduction which in turn reduces the overall size of the generating set