Patent ID: 6919711

Claim:
An AC electrical machine including a rotor, a stator and two sets of windings on the stator in which an emf is induced by rotation of the rotor, one of the two sets of windings on the stator being connected to a chargeable source of electrical potential, said AC electrical machine further including control means operable to effect operation of the AC electrical machine in one of two modes, the AC electrical machine being operable in one of the two modes to rectify an electrical potential generated by induction of an emf in said one set of windings and to conduct the rectified electrical potential to charge the chargeable source, wherein said one set of windings is connected to said chargeable source of electrical potential through bi-directional AC/DC conversion means and said control means are operable to effect operation of said bi-directional AC/DC conversion means in a respective one of two modes for each of said two modes of operation of the AC electrical machine, the bi-directional AC/DC conversion means being operable in said one mode of operation of the AC electrical machine to effect said rectification of the electrical potential to charge the chargeable source, and in the other mode to invert the electrical potential of the chargeable source into an AC potential and to apply that AC potential to said one set of windings whereby to produce a rotating magnetic field around the rotor and thereby to apply a driving torque to the rotor, to accelerate the rotor in response to an increase in load demand on the AC electrical machine, the emf induced in the other set of windings being available to meet a load demand on the AC electrical machine during both modes of operation of the AC electrical machine and during said other mode of operation of the AC electrical machine, to do so in combination with the emf induced in said one set of windings.