Power boost unit for automotive Electric Power Steering systems

In recent years the use of Electric Power Steering (EPS) in small and medium-sized cars has increased as it offers significant benefits such as reduction of fuel consumption as well as increased controllability. To enable the use of EPS systems in larger vehicles, the output power has to be increased without increasing the maximum current drawn from the battery. This can be achieved by using a Power Boost Unit (PBU) local to the EPS that incorporates a supercapacitor. The PBU provides a short burst of high current to meet transient load demands by exploiting the energy storage capability of supercapacitors. In this way, systems which operate at high power for a short term can be utilised without exceeding automotive battery current restrictions. This paper describes the design and operation of a 2kW prototype Power Boost Unit. Experimental results confirm the functionality of the unit.