IMPROVING ELECTRIC VEHICLE ENERGY EFFICIENCY WITH TWO-SPEED GEARBOX

Electrical Engineering, Automobile Engineering,Mechanical Engineering

This research focuses on improving electric vehicle energy efficiency with two-speed gearbox. Traditionally, the electric motor of an electric vehicle is coupled to driving wheels with a single-speed gearbox. Electric motor as a traction motor enables such drivetrain but with a single-speed gearbox the electric motor must operate in wide speed range. The use of wide speed range forces the motor to work in non-optimal speeds which effects on its energy efficiency. The possible energy efficiency improvement of electric vehicle with multi-speed gearbox is examined in this research. The benefits of two-speed gearbox were evaluated based on the simulation results provided by a developed simulation model. Evaluations were done by comparing the energy consumptions of the reference model to the model that utilizes a two-speed gearbox. Simulations also included an optimization study for determining the optimal gear ratios in order to minimize energy consumption. The results reveal that it is possible to improve energy efficiency with two-speed gearbox but it is heavily dependent on the motor efficiency map which in turn depends on the electric motor type. The benefit of a two-speed gearbox was slightly better in higher speed driving cycles.

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