This paper details MIRA's investigation into whether optimised phased regenerative brake systems are able to yield significant improvements in the recovery of braking energy, compared to non-phased systems. Unlike many other regenerative braking papers, this investigation provides actual comparative data for different regenerative braking conditions. This data was captured by comparing the relative energy recovery rates obtained using a prototype system fitted to a vehicle running on a transmission rig with full inertia simulation. These results were then used to assess whether a second larger project (using an optimised phased system) should be undertaken to develop two technology demonstrator vehicles which would be used for testing in the field.

This paper also addresses a number of technical issues associated with the design of phased and non-phased systems, and details the development of a practical actuation design to achieve improved vehicle control with respect to pedal travel and regeneration demand rates. It explains how pedal feel was tuned to suit the driver in a number of specific drive cycles. As well as defining actual energy recovery rates, work was done to explore the extent to which the net braking energy recovery rate depends upon:

• Differences between a standard emission drive cycle and actual real life driving cycles

• Deceleration, speed and driving styles

• Vehicle, E-machine and battery specification

The paper also provides comparative data for the energy savings achieved by the different regenerative brake control strategies and how an optimised system was able to achieve an increased energy saving of over 10%, compared to the original OEM's non-phased system.

Acknowledgement - This research was supported by the Dual-Use Program Cooperation Center in The Republic of Korea.

Curry, Eddie Curry, Andy Owen, H.S. Choi - MIRA, ADD (Agency for Defense Development)