This thesis further improves upon the original 10 MW design of the double claw pole
generator, by systematically addressing its shortcomings. The original design is a fully iron cored machine with a stationary superconducting field winding. Its structure allows it to be
highly modular, reliable and cost-effective. Its main disadvantages are, when compared to
other superconducting generator designs, its weight and efficiency.
The double claw pole generator is a large diameter iron-cored axial-flux machine, due to these
features a very stiff mechanical structure is required to main the air gap clearances, which
leads to a very heavy structural mass. A novel stator design is introduced, which partially
deviates the air gap closing forces into the radial direction, reducing the axial component of
forces. This enabled the structural mass to be reduced from 126 tonnes to 115 tonnes.
Secondly, the field core of the double claw pole machine was replaced by an inner stator. The
additional stator increases the electric loading of the machine while also further increasing its
modularity and improving the generator efficiency. With a target efficiency of 95 %, the power
output of the generator was increased from 10 MW to 11.5 MW, while maintaining the same
machine diameter and axial length.
To further increase the power density and modularity, the possibility of stacking machine
modules was explored. Stacking two standardised modules concentrically was found to result
in a smaller and lighter machine than the original design. Additionally, the standardised
modules, due to their smaller size, greatly simplify the transportation of the generator.
The addition of the inner stator was found to be a very promising design. It improves the
original concept of the machine in terms of power density, efficiency and modularity. It is
believed that this makes the design even more competitive in the high-temperature
superconducting generator market.
Finally, detailed electromagnetic modelling of superconductors was performed in the
electromagnetic environment relevant to electrical machines. Particular focus was put on the
dynamic loss mechanisms in superconducting field windings. Through the new knowledge
gained on the loss characteristics, the cooling requirements can be better understood,
potentially increasing the reliability of superconducting windings and their associated cooling
systems