In this paper, a hybrid model-based nonlinear optimal control method is used to compute the optimal power distribution and power management in parallel hybrid electric vehicles. In the power management strategy, for optimal power distribution between the internal combustion engine, electrical system and the other subsystems, nonlinear predictive control is applied. In achieving this goal, a hierarchical control structure is utilized. This type of control structure consists of three levels of monitoring, coordinating and local level. Nonlinear modeling and performance index in the proposed problem, shall be formulated at the regulatory level of the controller. Discrete dynamic mode of operation (motor-generator) in hybrid electric vehicle, requires us to use a dual-mode switch model and to define an alternative expression of performance index for the optimal control problem. In the performance index, tracking error penalty, fuel consumption, friction losses and the maintenance of the battery charge has been included. Optimization of performance index is performed by the theory of nonlinear model predictive control using numerical methods.
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