Investigation into regeneration regimes for converted electric vehicle in road tests

As fossil energy deposits are exhausted, internal combustion engine vehicles tend to be replaced by electric ones. Electric vehicles have several advantages over internal combustion ones: no exhaust emissions at the site of exploitation, emissions from energy production could be located in less populated areas, emissions are much lower, quieter operation and a two-fold higher efficiency factor of the motor. One of the most significant advantages of operating an electric vehicle in a city is the possibility of energy recovery, which allows the energy regenerated during braking to be charged into the batteries, thus increasing the range. An original research methodology for road testing has been developed and tested. Since regenerative braking usually occurs in parallel with braking by applying the service or friction brakes, it is difficult to determine the maximum amount of energy regenerated, as part of the kinetic energy is also transformed into thermal energy when braking. Therefore, a braking experiment with a converted electric vehicle Renault Clio Electro was performed by braking at different speeds only by means of regenerative braking, using no friction brakes. The experiment was performed in two of the most commonly used gears – second and third. The experiment recorded both the energy consumed to reach a certain speed and the energy returned to the battery during the braking cycle. The highest regenerative braking efficiency was achieved in second gear at a 100% regenerative braking setting, on average 35.1%, yet this regenerative braking setting was difficult to use in real driving conditions due to excessive braking and difficulty in controlling the braking torque and the deceleration of the electric vehicle. Therefore, a regenerative braking setting of no more than 80% is recommended for the experimental prototype in road traffic, reaching a regenerative braking efficiency of 32.5%.