BEV Powertrain Component Sizing With Respect to Performance, Energy Consumption and Driving Patterns

In this thesis, various drive cycles, legislative, official real-world and measured withinthe frame of the project, have been studied and characterized in terms of speed and accelerationcycle parameters, as well as acceleration and speed distribution. The objective was toassess typical vehicle usage on different road types, but also to study the implication on vehicleenergy consumption due to the drive cycle’s characteristics. For this evaluation, threereference vehicles were designed after different set performance requirements, with data onexisting BEVs as a frame of reference. An available traction motor, power electronic moduleand battery cell were utilized, where the motor was scaled by active length. Finally, theconsequence of downsizing the electric drive system in terms of energy consumption andperformance was also studied.Through comparison between legislative together with official real-world cycles andmeasured drive cycles, it was found that even though the measured cycles reach higherpeak acceleration levels for a certain speed level, they still spend only slightly more time athigher levels of acceleration compared to the official cycles, at least on average over a groupof similar cycles. During the powertrain sizing regarding torque and power, it turned out thatthe acceleration requirementwas dominating over other requirements such as top speed, andgrade levels. The analysis shows that for two cycles with similar speed parameters such asmaximum and average speed and time share at low speed, but where the speed time tracesare very different with many more speed fluctuations in one cycle compared to the other,in combination with generally higher acceleration levels, the increase in net battery energyconsumption per distancemay be as high as 28% for the cycle with more speed fluctuations.By down-scaling the electric drive system of the City car by 40%, the net battery energy perdriven distance for low speed cycles increased by about 3−6%, while three of the cyclescould not be fulfilled due to limited acceleration capability