Design Optimisation and Comparison of Large-Scale Non-Overlap Wound-Field Machines

As a departure from the more expensive PM machines, the design optimisation of non-conventional, non-overlap wound-field machines for large-scale wind power generation is demonstrated between wound-field flux switching machines (WF-FSMs) and wound-rotor synchronous machines (WRSMs), in this paper. Consequently, the three-phase, 10/12 WF-FSM and 16/18 WRSM are nominated and designed for geared medium-speed variable-speed wind generator drives. A multi-objective objective optimisation comprising active mass and torque ripple minimisation is instituted on both machines, based on finite element analyses. Despite the double salient feature of the WF -FSM, the same fidelity for torque ripple minimisation is reported as observed in the WRSM, but at the expense of 50 % reduction in the torque/mass ratio of the former. The pros and cons of the final machines are also discussed, after which an experimental approach, implemented in sub-scaled 10 kW prototypes, is presented.