Additional short circuited dem windings to compensate unbalanced magnetic pull (UMP) effects

摘要

An electromagnetic rotary machine comprising; a rotor and a stator 1, the rotor and stator being mounted in co-axial alignment with respect to each other and arranged such that one is rotatable relative to the other about their common axis and an air gap provided between the rotor and stator; at least one set of primary coils carried by one or both of the rotor and stator such that the net magnetomotive force (MMF) acting to drive magnetic flux across the air gap can be changed by changing the currents flowing in these coils with the result that torque can be produced tending to rotate one of the rotor or stator relative to the other is characterised by a second set of coils 2a, 2b carried by or positioned in close relation to one or both of the rotor and stator 2, the second set of coils comprising individual closed circuits configured such that a net loop electromotive force (EMF) is induced in the circuit by the occurrence of any imbalance in the flux on diametrically opposite sides of the rotary machine.