Traction energy saving potentials for electric cars with gear shift

Authors

Oliver Zirn, Fabian Schmiel, Esslingen University;
Matthias Dellermann, Daimler AG

Year

2019

Summary

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%. In this contribution, the motor characteristics with efficiency mapping are given for the complete drive chain (battery – current converter – motor – gearboxes – wheel).
With the actual electrical motor types asynchronous machine (ASM) and permanent magnet synchronous machine (PMSM) it is not possible to reach both, high velocity as well as high gradability together with high efficiency at low speed and small motor torque.

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