Conceptual Design and Evaluation of a Hybrid Transmission with Power-Split, Series, and Two Parallel Configurations 2017-01-1172

A hybrid transmission may be in any combination of a power-split, series or parallel configuration. This study is aimed to develop a hybrid transmission with six possible configurations: power-split, series, two parallel configurations, and two EV configurations. The Function Power Graph (FPG) methodology was applied in this study. After creating and merging FPGs, a possible solution consisting of only one planetary gearset, one ICE, one MG1, one MG2, two rotating clutches, and one brake clutch was synthesized to satisfy all configuration requirements. This transmission was based on power-split configuration which can switch to other configurations. The parallel configuration I extracted more power from MG1 and ICE during lower speed driving in order to utilize the two sufficiently, and respond to the increased desire for horsepower in the market. Additionally, parallel configuration II was set up so that ICE can directly propel the vehicle during freeway cruising. Compared with power-split configuration, MG1 does not need to keep operating in parallel configuration II, which gives an additional opportunity to develop an energy management strategy. Moreover, both MG1 and MG2 could propel the vehicle in the two-motor EV configuration, thus costly electric machinery and power electronics were utilized more thoroughly. In conclusion, a design process of a multi-configuration hybrid transmission was proposed and the result was evaluated. This study provides some alternative hybrid concepts for further research.