Mechanical flux weakening for a surface permanent magnet machine with split rotor

This paper presents a mechanical flux-weakening solution for Surface Permanent Magnet machines. In particular, a split rotor configuration (two independent rotor sections that can be phase-shifted) is discussed, in which the rotors shifting is achieved through a torque component generated inside the machine, without the need for any external actuation. The analysis demonstrates that the theoretical constant power speed range is infinite. The reliability of the active actuation through the shifting torque promises for a very wide achievable constant power speed range in practice.