| 摘要 |
<p>An electric motor comprising a stator having a plurality of coils, a rotor having a plurality of permanent magnets and a controller that is arranged to provide a voltage to the plurality of coils to generate a current through the coils A, B, C that is defined by a stator current vector Is. The controller is arranged to freeze the angle of the stator current vector unless the angle between the stator current vector and a rotor magnetic flux vectorΨRassociated with the rotor magnets exceeds a predetermined value. If the predetermined value is exceeded the controller is arranged to synchronise the movement of the stator current vector to the movement of the rotor magnetic flux vector. The arrangement allows a progressive braking torque to be applied to an electric motor, where the braking torque varies based upon the relative movement of the electric motor's stator and rotor, and minimises the risk of the electric motor oscillating when a zero speed condition is approached. The arrangement is particularly suitable for regenerative braking an electric vehicle.</p> |
