Performance evaluation of regenerative braking systems

This research evaluates the energy gain from a regenerative braking system (RBS) in a commercial electric vehicle (EV), the OEM Mitsubishi i-MiEV. Measurements were conducted in a controlled environment on a commercial chassis dynamometer using international drive cycle standards. The energy recovery of the vehicle was modelled and the output of the model was compared with results from the chassis dynamometer driving. The experiments were original as they coupled changes in energy recovered and driving range due to the RBS settings with investigations into the time of use of the friction brake. Performance tests used two different drive cycle speed profiles and various RBS settings to compare energy recovery performance for a broad range of driving styles. The results show that due to reduced energy consumption, the RBS increased the driving range by 11-22% depending on RBS settings and the drive cycle settings on the dynamometer. The results further showed that driving an EV with a RBS uses the friction brakes more efficiently, which will reduce brake pad wear. This has the potential to improve air quality due to reduced brake pad dust and reduces the maintenance costs of the vehicle. The findings were significant since they showed that friction time of use, a parameter neglected in RBS testing, plays an important part in the efficient operation of an EV. The overall results from the vehicle energy recovery modelling showed good agreement with the data from drive cycle testing and the model has potential to be further developed to gain greater insight into vehicle RBS braking behaviour for EVs in general.