ELIMINATION OF TORQUE PULSATIONS IN A DIRECT-DRIVE EV WHEEL MOTOR

Double sided axial field machines are attractive for direct wheel driv es in electric vehicles. This is due to the fact that stator/rotor mis alignments can be accommodated. In this case the stator of the machine is envisaged mounted on the chassis of the car whilst the rotor direc tly drives the road wheel. Since the wheel is perturbed by the road su rface the rotor will move vertically between the outside stator assemb lies and thus give rise to torque pulsations. A vector control scheme has been implemented whereby the torque pulsations are eliminated by ( i) calculation of the flux variation due to the rotor perturbation and (ii) using this signal for the modulation of the motor input current.