Traction energy saving potentials for electric cars with gear shift

The efficiency of electrical traction drive chains is quite good (i.e. above 80%) in a wide operation range, while for low speed or small torque operation, efficiency falls significantly. In realistic load cycles, electric drives often have to work with efficiency levels below 60%. This is elucidated in Fig. 1 for the experimental vehicle shown in Fig. 2. In this contribution, the motor characteristics with efficiency mapping are given for the complete drive chain (battery – current converter – motor – gearboxes – wheel).