This paper discusses a high frequency high power transformer to rotate an armature winding and the new motor drive system. The rotating transformer supplies the power from the movable part to the unmovable part by the wireless power transmission technique. The rotating transformer has an advantage of the maintenance-free as usual slip ring system has. Thus, we calculate its volume and weight from the control conditions and the theoretical formula. Moreover, we compare the weight and the size of the slip ring and the rotating transformer system. After that, we choose the best rotating transformer model and show the characteristics against to the variable load. Through the rotating transformer, single-phase power converts a three-phase power, the rectifier circuit independently drive the SR motor by a high frequency control.