Efficiency improvement in DC and AC motor powered electric vehicles

Electric vehicles seem to be a solution against the greenhouse gasses emission problem. The major problem of these vehicles is low autonomy, due to the low energy density of the batteries, compared to gasoline. A way of dealing with this problem is to increase the vehicle´s efficiency, by minimizing the power losses. In this paper, ways of minimizing the power losses for DC and AC motor powered vehicles via adjusting the gear ratio and the motor´s magnetic flux are studied. To do so, the losses of all parts of the electromechanic system are calculated as a function of the gear ratio λ, and the motor´s magnetic flux CΦ, with the vehicle´s speed and resultant force as parameters. It can be proved that for each pair of parameters there is an optimum set (CΦ, λ) that minimizes the vehicle´s losses. Finally, the theoretical analysis is verified by experimental results.