Abstract: A motor/generator unit is disclosed which is arranged to be fitted in the drive train of a vehicle, such as a hybrid vehicle. The unit comprises an electrical machine (10, 12) and a housing arrangement (14, 16). The housing arrangement comprises an inner housing (14) arranged to accommodate the electrical machine, and an outer housing (16) arranged to fit around the inner housing. This can allow the electrical machine to be provided as a self-contained unit suitable for use in different applications.

Abstract: A rotor disc is disclosed for an axial flux permanent magnet rotating electrical machine. The rotor disc (12) comprises a plurality of laminations in a radial direction through the rotor disc, and a plurality of slots which pass radially through successive laminations for accommodating permanent magnets (14). The rotor disc may be formed from a spirally wound strip of material, or from groups of laminations.

Abstract: An axial flux rotating electrical machine is disclosed, which comprises a stator sandwiched between two rotors. The machine comprises retention means for retaining magnets on the rotor, the retention means comprising a back plate with a plurality of protrusions which define a plurality of pockets for accommodating the magnets. The retention means is arranged such that the magnets can be inserted into the pockets and held therein, and the retention means with inserted magnets can be fixed to a rotor so as to retain the magnets axially and tangentially. A cooling jacket for the stator, and techniques for securing the stator to the machine, are also disclosed.