Low speed test in two-axis actively positioned bearingless machines with non-collocated structure for wind power applications

This paper presents low speed test in two-axis actively positioned bearingless machines with non-collocated structure for wind power applications. Bearingless machines have been required in wind power applications to eliminate bearing failures. In the two-axis actively positioned bearingless machine, radial directions are actively positioned. Normally, tilting and axial motions are passively stabilized so that serious vibration sometimes occurs when disturbance is applied. In particular, the tilting vibration occurs in non-collocated structure because of interference with the radial force. In this paper, a disk-shaped multi-pole bearingless machine with a fan blade is presented. Four rotors with non-collocated structure are compared in rotation tests. An appropriate integral gain for stable magnetic suspension is calculated by proposed mathematical equation. In low speed rotation tests, radial and tilting vibrations are evaluated.