Methodical approach for designing electric propulsion systems containing two motors

To reduce the environmental impact of the petroleum-based transport, new safe, cost and energy optimized electric vehicle propulsion concepts are mandatory. Besides the activities for improving the battery and power electronics technologies, highly integrated units and new functional component operation strategies are of special interest. In this paper, a methodical approach for deriving electric motor design values for electric propulsion systems, especially usable for urban vehicles, including two electric machines, is shown. Considering the overall results a new highly integrated electric drive containing two different sized electric motors, two clutches and a compressor in one single unit is used as an example. The design led to a variety of functional motor modes presented in the paper. On upscaled measurement results, the efficiency tables for 50 kW and 10 kW PSM- and ASM-motors are used for a combined working strategy. Using the 10 kW motor on low torque and speed requests the traction energy demand of a urban vehicle could be reduced in the range up to 5% on several drive cycles.