Thermal Duty Cycle Requirement Development and Enforcement in an Electric Power Steering System

Thermal duty cycle requirements in an electric power steering (EPS) system are a major cost driver. In order to develop these requirements, a technique has been developed to analyze load and time data from a vehicle level schedule and condense the load and time data into a compact specification for thermal duty cycle. This allows the duty cycle requirement to be determined at the vehicle level by the end customer and flowed down appropriately to the steering system and its components. In addition, a method which mimics the requirement process is used by the EPS algorithm to provide duty cycle enforcement and hence thermal protection, reducing the need for temperature measurement sensors.