An Efficiency Optimized Gear-Shift Map to Maximise the Performance of a Modular E-Axle

This paper summarizes the development of an efficiency optimized gear-shift map to maximize the performance of a 9-tonne modular e-axle for all-terrain heavy-duty vehicles. Raw power loss data for an inverter and motor system is analyzed and processed, resulting in component power loss and efficiency maps for each component along with combined inverter and motor system. The e-axle efficiency maps for each gear were calculated and mapped to a common set of lookup vectors before the most efficient gear for each operating point was selected. The usefulness of the e-axle power loss maps for sizing vehicle cooling packs was demonstrated through a simulation of the California Air Research Board (CARB) Heavy Heavy-Duty Diesel Truck (HHDDT) Composite Cycle.