Ringed-Pole Permanent-Magnet Synchronous Motor for Position Sensorless Drives

A new configuration of surface-mounted permanent-magnet motor in which a copper turn has been wound around each pole is investigated. The purpose is to modify the high frequency direct axis inductance, without affecting the quadrature axis one, creating a rotor high frequency anisotropy. Therefore, position sensorless control technique exploiting the anisotropic rotor features by injecting high frequency signals can be used. After describing the machine structure, the main equations dealing with the rotor dynamic anisotropy are identified. The sensorless control technique is then discussed and expected drive sensorless performance is validated by simulation and experimental results.