Prediction of the electromagnetic torque in synchronous machines through Maxwell stress harmonic filter (HFT) method

For the calculationof torque in synchronousmotors a local method is analysed, based on the Maxwell stress theory and the filtered contributions due to the harmonics of the magnetic vector potential in the motor air-gap. By considering the space fundamental field only, the method can efficiently estimate the average synchronous torque for a variety ormotor topologies, including concentratedwinding designs. This approach employs an analytical filter for the Maxwell stress tensor and ‘frozen permeability’ technique. The proposed method is validated by comparison with FE results for several synchronous motor types: interior permanent magnet motors, wound field motor, synchronous reluctance motor.