A Hybrid-Electric Power Transmitting Unit for 4x4 Vehicle Applications: Modeling and Simulation

In this paper, a technical concept is described for a hybrid-electric power transmitting unit (HE-PTU) to control the split of power between the drive axles of a 4×4 hybrid-electric vehicle. This new power transmitting unit is a mechatronic systems by its design and uses a planetary gear set and eddy current brake to provide a continuously variable (dynamic) gear ratio that can be integrated into the vehicle driveline between the transfer case and front axle. The paper details the electrical and mechanical characteristics of the device, including its various operation modes, its mathematical model built from the equations of the planetary gear set and eddy current brake, an optimization condition by which the device will be controlled to improve vehicle energy efficiency, as well as its torque and electrical current usage. Computer simulations are performed on a mathematical model of a 4×4 military truck using the power transmitting unit in conjunction with a series hybrid-electric configuration transmission.