Integrated Design and Optimization of a Direct Drive Axial Flux Permanent Magnet Generator for a Tidal Turbine

Abstract

The C-GEN is a novel topology of direct drive

air-core permanent magnet generator being developed at

University of Edinburgh [1]. The topology has many benefits

such as; absence of cogging torque, reduced mass and ease of

manufacturing. A 20 kW prototype test rig and 15kW machine

for a wind turbine has been manufactured and tested previously.

Initial sizing studies for wind turbines indicate that the C-GEN

concept will be up to 50% lighter than conventional iron cored

PM direct drive generators [1]. In addition to the applications

wind turbines, C-GEN technology can also be implemented for

marine energy power take-off systems. To investigate that, a

feasibility study is being undertaken in collaboration with two

wave and two tidal energy companies.

In this paper, design and optimization method of an axial flux

permanent magnet generator for a tidal energy converter device

has been investigated. An analytical optimization tool is

designed that combines electromagnetic, structural and thermal

aspects of the machine design. A genetic algorithm optimization

method has been utilized based on the operation conditions of

generator and pre-defined constraints on dimensions and

material limitations. The output of the analytical design tool is

compared with the electromagnetic FEA simulations. The

results showed that proposed analytical calculation method is

consistent with FEA results