Cost Optimization of E-Drives for Traction Applications

摘要

E-drives are used in powertrain configurations that are subject to large cost pressure.Reduction of vehicle cost can be achieved by reducing the component cost. For batteryelectric vehicles reduction of the battery size is a big cost lever. This can be achievedby increasing the efficiency without reducing the range.Copper and magnets are expensive components in e-motors. The performance of ane-motor is limited by heat rejection. The size and material effort of an e-motor can bereduced with improved cooling while maintaining the same power output. The effectsof oil-cooling on both stator and rotor is investigated.In inverters, the DC link capacitor is one of the main cost driving components. Theminimum required capacitance is investigated. The DC link capacitor is driven by criticalhigh load operating points. In other operating points, the oversized DC link capacitorallows for variations of the switching strategy. The effect of switching frequencyreduction as well as flat top modulation is investigated. Both measures lead to an increaseof inverter efficiency. The inverter power losses are reduced by up to 1400 W.At peak efficiency, the efficiency is increased by 0,55 percentage points.The benefits of the optimized switching strategies are evaluated in a battery-electricSUV. The energy consumption is reduced by up to 4,9 % in the city part of the WLTC,and it is reduced by up to 2,4 % in the whole WLTC. All modulation measures combinedimprove the range of the vehicle by 12 km without changing any components.