Research Of A New-type Hybrid Power Split Unit Based On Two Planetary Gear Sets

As the environmental pollution and energy crisis are becoming moreand more severe, in order to improve the economical efficiency and reduceemission of the fuel, Hybrid electric vehicle (HEV) techniques aredeveloping rapidly worldwide. In the States, Europe, and Japan, greatprogress has been achieved in the research of HEV since the90s of the20thcentury, especially the technique of powertrain system using planetary gearsets as the power split power coupling mechanism. For example, theToyota Hybrid System (THS) and the GM2-Mode power system. However,for both power split power schemes, there are deficiencies: THS has onlyone power split mode, which requires high motor speed; GM2-Mode needsthree rows of planetary gear sets, which occupy large space and generallyare only fit for SUV.In this paper, we designed a two-row planetary gear sets powercoupling scheme (GFE power scheme), which combines speed coupling andtorque coupling. The power-coupling scheme includes two rows ofplanetary gear sets, four clutches, one engine and two motor generators(MGA and MGB). Under hybrid drive, there are two power split modes:input split and compound split. In this paper, the lever method is applied fora dynamics analysis of the clutch engaging in the two-row planetary gearsets power coupling mechanism. Based on the analysis, we divided the workmodes of the GFE power scheme. Then, according to the power demand ofthe designed scheme, we perform the parameter matching for the GFEhybrid vehicle parameters and each power element parameter, using aprototype vehicle as reference.Based on the analysis of the GFE power scheme, we created arule-based logic threshold value energy management and control strategy. The strategy includes the calculation of torque requirement, the selection ofwork mode and the allocation of torque under different word modes. Thesimulation model is established for the control strategy inMATLAB\SIMULINK\STATEFLOW.Finally, in order to evaluate the feasibility of the proposed GFE powerscheme and its control strategy, we modeled the vehicle using AVL CRUISEsimulation software, imported the previously established control strategymodel in the form of a.dll file, and performed a simulation analysis of thepower performance and the fuel economical efficiency of the vehicle.