Optimal Design of Single-Mode Power-Split Hybrid Tracked Vehicles

Abstract

Hybrid tracked vehicles are common in construction, agriculture, and military applications. Most use a series hybrid powertrain with large motors and operate at a relatively low efficiency. Although some researchers have proposed power-split powertrains, most of these would require an additional mechanism to achieve skid steering. To solve this problem and enhance drivability, a single-mode power-split hybrid powertrain for tracked vehicles with two outputs connected to the left and right tracks is proposed. The powertrain with three planetary gears (PGs) would then be able to control the torque on the two tracks independently and achieve skid steering. This powertrain has three degrees-of-freedom (DOF), allowing for control of the output torques and the engine speed independently from the vehicle running speed. All design candidates with three PGs are exhaustively searched by analyzing the dynamic characteristics and control to obtain the optimal design. Efficient topology design selection with parameter sizing and component sizing is accomplished using the enhanced progressive iteration approach to achieve better fuel economy using downsized components.