Research on the dynamic power split characteristics and the electric power coordinated control for a hybrid transmission system

The power-split hybrid transmission system can enhance the fuel economy by adjusting the engine operating points, and take full advantage of high efficiency of the mechanical transmission. So it is a good solution for applying the hybrid electrical driving to the heavy vehicle. Based on the power-split scheme and the static characteristics, the power split characteristics can be achieved from the restriction relation and the system parameters. But in the actual driving condition the dynamic response and the nonlinear characteristics has remarkable affect to the power status. So in this paper the dynamic and nonlinear characteristics of the power components and transmission machine are introduced into the power analysis of the power-split hybrid transmission system. The analysis indicates that the delay of the engine torque would decrease the electric generation by the generator motor. Aiming at the precision of mechanical and electrical power distribution and the responding speed of electrical power supply, a closed-loop electric power coordinated control strategy was proposed to meet the demand of vehicle power performance and electricity. The simulation and bench test results indicate that the complex dynamic control problem of the precision of mechanical and electrical power distribution and the responding speed of electrical power supply can be solved well by the closed-loop electric power coordinated control strategy.