Design and evaluation of a 1.2 kVA single phase rotary transformer

The doubly fed induction generator (DFIG) is the most popular choice for wind energy generation systems. The cost and difficulty incurred in the maintenance of the slip rings has led to the development of the brushless DFIG. Amongst other design options, the brushless DFIG can be realized through the use of rotary transformers (RTs). Due to the low operating frequency of the rotor currents, a RT used in place of slip rings in a conventional DFIG configuration, can be bulky. However, by utilizing a rotor tied to the grid DFIG system configuration, the RT's operating frequency can be increased to the grid's frequency. In this paper a single phase 1.2 kVA RT is designed, using a previously proposed optimal design method, and developed. Three of these RTs can be used in place of the slip rings in DFIGs. Remarkable measurement results as well as simulation results are also presented.