This paper describes the modeling of dual hybrid electric vehicle drivetrain and proposes a hybrid control system for controlling the drivetrains.
In dual hybrid electric drivetrains, the energy from the engine passes through the planetary gear set and is split into generator and motor paths. A complete dual hybrid electric drivetrain system model is developed. The modeling process is discussed for each of the major components of dual hybrid electric drivetrain, such as planetary gear transmission, gasoline engine, motor, generator and vehicle dynamics. Integrated nonlinear model and effects of parameter variations are also studied.
Hybrid control system, which is a discrete-event system interacting with continuous-state system, is suitable for modeling and control of the systems that have state jumps and dynamics changes. In this paper, on/off state of engine is treated as a discrete state of HEV system and, velocities and torques as continuous states. The proposed hybrid control system consists of continuous-state plant to be controlled, continuous-state controller, interface, and discrete-state controller. Continuous-state controllers for each discrete modes of continuous-state plant are designed. Optimal torque map for engine-off mode and a robust linear controller which can stabilize the parametric uncertain system for engine-on mode are proposed. A reference management technique is developed to avoid the saturation of control input since the saturation due to the characteristics of motor and generator can cause instability of the system. A sensitivity analysis is carried out for the discrete-state controller. Simulation results are also presented comparing the performance of the proposed hybrid control system with that of the conventional HEV controller.
