Reluctance torque evaluation for interior permanent magnet machines using frozen permeability

This paper proposes an accurate model which allows for separation of torque components based on frozen permeability concept for interior permanent magnet machines. An additional torque component due to the interaction of the rotor magnetic field with unequal d and q-axis reluctances in the stator iron is included. The proposed model can reproduce the instantaneous torque waveform at any load condition, and hence provides a more accurate means of reluctance torque evaluation compared with the conventional methods.