In case of a gear change in one subtransmission the driving motor of the other STM is still propelling the vehicle. The synchronization of speeds is executed by active speed control of the electric motors. The entire control software was commissioned, tested and optimized in the demo vehicle. The following diagram shows the measurement results of a seamless electric power upshift.
Subjective assessment as well as objective evaluation criteria for shift comfort show a high level of shifting comfort for both pure electric and hybrid gear changes. The subjective assessment of the comfort for partial and for high load electric gear shifts of 23 powertrain experts is shown in the following. In particular, the gear shifts in electric partial load operation are assessed as not perceptible.