Abstract: Hybrid vehicles have two or more sources of on-board power. A power control strategy, referred to as the “energy management strategy”, is needed to coordinate all the components of powertrain so that they can work together in an optimal manner (optimal vehicle operating mode and optimal power distribution) to achieve multiple design objectives, such as high fuel economy and low emissions. An innovative four-step design method is presented and an optimal energy management strategy for a power split powertrain hybrid vehicle is designed. In the first step, a hybrid dynamical system theory is introduced to formulate the hybrid vehicle control system that incorporates both continuous and discrete dynamics. In the second step, the sequential quadratic programming (SQP) method is applied to optimize power distribution. The dynamic programming method is employed to solve the complex vehicle operating mode transition problem. In the third step, a rule-based system and a fuzzy rule system are developed based on the statistical numerical solutions derived from the second step. In the fourth step, a genetic algorithm is applied to the simultaneous optimization of parameters of membership functions, weights of the rules and rule sets for fuzzy rule system and parameters of the rule-based system.

Key words: Dynamic programming, Energy management strategy, Genetic algorithm, Hybrid dynamical system, Hybrid vehicles