Wheel & Axle Disconnect Controls on Hybrid Electric Powertrains

With the proliferation of electric vehicles in the market, it has become important for Automotive OEMs (Original Equipment Manufacturers) to focus on delivering a higher driving range while also maximizing performance. One approach OEMs are actively considering in meeting this goal is to include a secondary drive axle disconnect into the powertrain which has the potential to improve the overall driving range by about 6-8.3% [4]. This paper outlines the need for a novel controls architecture to make the Powertrain controls software modular and to reduce the development time needed to provide robust powertrain control software. To do this, the electrified powertrain torque controls at STELLANTIS NV takes a decentralized controls architecture approach, by separating the axle disconnect controls subsystem (ADCS) from the primary path of torque controls. The ADCS takes in information such as the desired axle state and controls the axle disconnect actuators to achieve that state. It then communicates back the current status to the primary torque path, like an external “secondary” controller. ADCS also interacts with the primary torque path by providing finalized target motor speeds for synchronization, axle disconnect torque estimates, and axle disconnect torque limits within which the electric machines must remain. This approach enables us to have a common primary path across the powertrain architectures, thereby improving development time, and carrying forward lessons learned from previous powertrain programs.