Computer aided design of a compact doubly-fed induction generator for small wind power application

The doubly-fed induction generator (DFIG) has advantages in wind energy applications while considering for the economy, quality, and the controllability of the system at various speeds. So as to take advantage of these factors in an effective manner, the DFIG has to be designed with all the degrees of freedom available for the optimum design of the machine. This includes, stator to rotor turns ratio, integral and fractional slot winding and winding layers, apart from the conventional design variables such as magnetic loading, electric loading, stack length to bore diameter ratio, stator current density, rotor current density, stator slot opening to stator slot pitch ratio and rotor slot opening to rotor slot pitch ratio. This paper brings out a computer aided design approach for the design of an efficient and compact DFIG meant for small wind power generation to the tune of 2 kW. Comparison with the conventionally designed DFIG of the same rating reveals that the newly designed DFIG is better in term of lower volume and better efficiency. The new design logic has resulted in reduction in the active volume of the machine, lower airgap harmonics and higher variable speed efficiency.