a three - phase / two - phase rotary transformer , includes a first single - phase rotary transformer and a second single - phase rotary transformer , the first transformer including a first body defining a first slot , a first coil in the first slot , a second body defining a second slot , and a second coil in the second slot , the second transformer including a third body defining a third slot , a third coil in the third slot , a fourth body defining a fourth slot , and a fourth coil in the fourth slot , wherein one terminal of the first coil is connected to the midpoint of the third coil , the first body , the first coil , the third body , and the third coil forming a three - phase portion of the transformer , the second body , the second coil , the fourth body , and said fourth coil forming a two - phase portion of the transformer .