1 kW/60,000 min-1 bearingless PM motor with combined winding for torque and rotor suspension

Abstract

A comprehensive description of a bearingless permanent magnet synchronous machine is presented including simulation, design, control and measurement focusing on a 1 kW/60,000 min-1 machine. A combined six-phase winding is used for the excitation of the two-pole motor field wave and the four-pole levitation field wave by applying two parallel three-phase current systems. The decomposition into the individually controllable current systems for motor torque and lateral rotor position control and the calculation of the relevant control parameters is explained. Measurements give an insight on the controlled motor performance. Thus, it is shown that the combination of torque and lateral force production with a single six-phase winding, fed by two three-phase inverters, not only leads to advantages in winding manufacturing but can be operated with a conventional field-oriented control also at high speed.