Analysis of a Novel Stator Construction Employing Steel Wire in Place of Laminations

This paper examines a novel method of constructing large diameter generators using many layers of steel wire in place of laminations. The stator coreback is formed by winding thin steel wire around the outside of the armature coils and then encapsulating the structure in epoxy. This technique simplifies the manufacturing process by removing the requirement to build a large support structure to carry the laminations. The electromagnetic behavior of a wire coreback is very different from traditional laminations, however, and produces abrupt changes in flux density across its thickness. The material is difficult to model using conventional FEA techniques due to the large number of elements required to mesh the small diameter wire. This paper examines two alternative modeling approaches. Method 1 uses two-dimensional (2-D) FEA to model the steel wire as a lamination oriented in the “wrong” direction. Method 2 uses a quasi-analytic approach based on detailed 3-D FE analysis of a small section of the generator to capture the flux density profile in the airgap. The two models are benchmarked against a prototype generator tested in the laboratory, and it is shown that the quasi-analytical technique gives the most accurate prediction of performance.

[1]  J. R. Bumby,et al.  Axial-flux permanent-magnet air-cored generator for small-scale wind turbines , 2005 .

[2]  David G. Dorrell,et al.  Design and Operation of Very Slow Speed Generators for a Bristol Cylinder Sea Wave Generating Device , 2014 .

[3]  Guobiao Gu,et al.  Analysis of temperature distribution for the electric generator in rim-driven marine current power system , 2013, 2013 International Conference on Electrical Machines and Systems (ICEMS).

[4]  Mohamed Benbouzid,et al.  Comparison of direct-drive PM generators for tidal turbines , 2014, 2014 International Power Electronics and Application Conference and Exposition.

[5]  Mohamed Benbouzid,et al.  An up-to-date review of large marine tidal current turbine technologies , 2014, 2014 International Power Electronics and Application Conference and Exposition.

[6]  Franck Scuiller,et al.  Rough design of a Double-Stator Axial Flux Permanent Magnet generator for a rim-driven Marine Current Turbine , 2012, 2012 IEEE International Symposium on Industrial Electronics.

[7]  Yulia Alexandrova,et al.  Lightweight stator structure for a large diameter direct-drive permanent magnet synchronous generator intended for wind turbines , 2015 .

[8]  E. Spooner,et al.  Lightweight ironless-stator PM generators for direct-drive wind turbines. , 2005 .

[9]  R. Nilssen,et al.  Large-diameter ironless permanent magnet generator for offshore wind power application , 2012, 2012 XXth International Conference on Electrical Machines.

[10]  M. Molinas,et al.  Efficiency calculation and improvement of a large-diameter ironless permanent magnet generator , 2012, 2012 15th International Conference on Electrical Machines and Systems (ICEMS).

[11]  C. Cossar,et al.  Comparison of High Pole Number Ultra-Low Speed Generator Designs Using Slotted and Air-Gap Windings , 2012, IEEE Transactions on Magnetics.

[12]  Suleiman Abu Sharkh,et al.  Structurally Integrated Slotless PM Brushless Motor with Spiral Wound Laminations for Marine Thrusters , 1988 .

[13]  Ahmad Darabi,et al.  Design and Performance Analysis of Superconducting Rim-Driven Synchronous Motors for Marine Propulsion , 2014, IEEE Transactions on Applied Superconductivity.