Torque Architecture For The Propulsion Supervisory Controller Of An Independent Axle All-Wheel Drive Electric Vehicle

This study describes the development of the Propulsion Supervisory Controller for an independent axle All-Wheel Drive Electric Vehicle, using a model-based approach. The vehicle has a main rear motor and a smaller front motor. Features like power moding, transmission range selection and torque architecture are discussed. For the torque architecture, different torque distribution strategies are explored in detail. Initially, a comparison of torque distribution strategies considering positive torques only, is used to assess the impact on the vehicle's energy consumption. Firstly, an optimal strategy with and without power-rate penalties is explored, which distributes the torque request to minimize the losses in both drive-units. Secondly, a fixed-ratio strategy is considered where both axles contribute with a predetermined torque ratio to meet the total torque demand. Thirdly, a torque-assist approach is examined, wherein only the rear motor contributes to the torque demand till it is operating at instantaneous maximum torque, after which the front motor starts contributing. Similar evaluations are then performed including regenerative braking or negative torque domain. Additionally, the performance of the penalized optimal strategy (PO) for positive torques is evaluated when combined with the torque assist regenerative braking strategy, where the front motor is primarily used for regenerative braking. The performance of PO combined with the ideal regenerative braking strategy is also assessed. This study aims to provide an overview of the controller development approach and an insight of the feasibility of deploying sophisticated computational algorithms for enhanced efficiency on it.