Patent ID: 6864662

Claim:
An electric power steering assist system for an automotive vehicle comprising vehicle wheels and a steering column rotatable by an operator to turn said vehicle wheels, said system comprising: a brushless electric motor comprising a stator for generating an electromagnetic field and a rotor disposed within said electromagnetic field and operatively coupled to said vehicle wheels, said rotor being rotatable at a motor speed and having a maximum design motor speed; and space vector modulation control module for determining electric current to said stator to rotate said electromagnetic field and thereby rotate the rotor, said space vector modulation control module comprising means for determining a desired quadrature axis current component responsive to rotation of said steering column, and means for determining a desired direct axis current component based upon motor speed such that said desired direct axis current component is zero when said motor speed is less than or equal to the maximum design motor speed and said desired direct axis current component is negative when said motor speed exceeds said maximum design motor speed.