Electric power assist steering system and method of operation
US6864662B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 30, 2003 |
| Grant date | Mar 8, 2005 |
| Priority date | — |
| Expiry date | May 11, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P21/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electric power steering assist system for an automotive vehicle comprises a brushless electric motor and a control module for regulating the motor based upon space vector modulation. In response to a steering command, the control module determines a desired quadrature axis current component to provide torque assist in turning the wheels. Also, the control module determines a desired direct axis current component based upon the motor speed such that the desired direct axis current component is zero when the motor speed is less than or equal to the maximum design motor speed, and is negative when the motor speed exceeds the maximum design motor speed. By utilizing a negative direct axis current component, the control module implements a field weakening effect within the motor that allows the motor speed to be temporarily increased greater than the maximum design motor speed to react to rapid steer commands by the operator, such as encountered in evasive maneuvers and the like.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.