Rapid Optimization of Multiple-Planetary-Gear Power-Split Hybrid Powertrains

In recent years, clutches have been used to create multi-mode power-split hybrid electric vehicles (HEVs). Designing an HEV for optimal performance is computationally intensive because of the enormous design space. For single planetary gear (PG) or a double-PG hybrid powertrains, the design with the best fuel economy and launching performance can be identified through exhaustive search. Exhaustive search for a hybrid powertrain with 3PGs is computationally expensive, because of the astronomical number of design candidates. To address the design problem with extremely large design space, a rapid structure optimization method is proposed, which is based on combining different operating modes. A case study compares several different schemes against the results of the exhaustive search. The results show that the proposed mode combination method can identify almost 90% of the best designs. The proposed method shows great potential when applied to hybrid systems with three or more PGs.