Optimal torque management strategies for all-wheel-drive electric motorcycles

The need for more sustainable mobility is fostering the electrification of all types of road vehicles. Electrification has also led to increased interest in multi-motor solutions for all-wheel-drive powertrains, to the benefit of handling and stability, and offering the possibility of reducing energy usage thanks to the optimisation of multi-motor torque management. This paper investigates whether the energy efficiency of a dual-motor, all-wheel-drive electric motorcycle is greater than the efficiency of a standard single-motor, rear-wheel-drive one. A mathematical model for the estimation of the driving losses is presented first. The model is then used to develop an optimal torque management strategy that minimises powertrain losses under propulsion as well as a strategy that maximises energy recovery under braking. A case study is used to quantitatively assess the proposed strategies, which are also compared to the performance of standard rear-wheel-drive motorcycles both in terms of energy efficiency and riding safety. Simulation results highlight that the all-wheel-drive electric motorcycle outperforms the rear-wheel-drive both in terms of energy efficiency and tyre-road friction usage. Overall, the maximisation of energy efficiency or safety - depending on specific driving conditions - is achievable with a feed-forward torque management system.