Development of a Compound Power-split Hybrid Power System for Commercial Vehicles

A novel compound power-split hybrid power system based on two planetary gear sets for commercial vehicles is developed. The equivalent lever diagram is used to investigate the components speed and torque characteristics of the system, and then the system dynamic torque control and transmission efficiency are described in equations. Six types of operating modes which are divided into two pure electric modes and four hybrid modes are analyzed by the simplified combined lever diagrams, and their torque decoupling in form of formula is derived. The hybrid transmission (HT) external characteristic is analyzed simultaneously. A control strategy which implements the rule-based (RB) method for the system is depicted. To evaluate the performance of a hybrid vehicle equipped with this hybrid system, the vehicle control and physical models are developed. Then power performance and economic performance simulations are performed. Meanwhile, corresponding tests are carried out to validate simulations. Simulation and test results indicate that, the fuel consumption for C-WTVC of the vehicle equipped with the proposed hybrid system is about 11 L/100 km and it declines by 21% compared with 14 L/100 km of the traditional vehicle.