Electro-mechanical differentials for reduction of self-generated wind-up torques in DBW AWD propulsion mechatronic control systems

Abstract

This paper deals with the concept of 'passive' and 'active' electromechanical (E-M) differentials in automotive mechatronics, in particular, for reduction of 'self-generated wind-up torques' in drive-by-wire (DBW) all-wheel-drive (AWD) propulsion mechatronic control systems. Self-generated wind-up torques are created by differing dynamic wheel-tire diameters, kinetic slip between front-wheel-drive (FWD) and rear-wheel-drive (RWD) units during cornering and kinetic slip between the driven wheels or steered, motorized and/or generatorized wheels (SM&GW) of one FWD or RWD unit. However, dissimilar transmission ratios for FWD and RWD units of a rigid DBW AWD propulsion mechatronic control systems, which also could create high self-generated wind-up torques, are usually not selected. The selfgenerated wind-up torques emerging in the DBW AWD propulsion mechatronic control system can only be reduced by power that linearly increases with the wheel angular speed. This power loss, in fact, cannot be utilized as tractive power for the all-terrain (on/off-road) all-electric vehicles (AEV), that is, battery electric vehicles (BEV) and fuel cell electric vehicles (FCEV) as well as hybrid-electric vehicles (HEV). The generated power loss increases the electrical energy economy and/or specific fuel consumption (SFC), the wear and tear (W&T) of all DBW AWD propulsion mechatronic control system components, and the wheel-tire wear. Under extreme circumstances, over heating and overload can significantly moderate the fatigue life and lead to an early failure of all DBW AWD propulsion mechatronic control system components.