Multi-objective Optimization of Hybrid Electric Vehicle Equipped with Power-split Continuously Variable Transmission

This paper aims to find the efficient state of hybrid electric vehicle (HEV) by simultaneousoptimization of the control strategy and the power train. The power transmission employed in thisvehicle is a power-split continuously variable transmission (CVT) which uses several fixed ratiomechanisms. After describing this transmission, the rules of electric assist control strategy areintroduced. A modification on this strategy is proposed to decrease the start/stop frequency of theengine and electric motor. Afterwards, an optimization on the HEV’s power train size, power-splitCVT and the control strategy is accomplished with the aim of minimizing the vehicle fuel consumptionand emissions. The optimization results are some Pareto-optimal points which are tradeoff solutionsbetween fuel consumption and emissions. Finally, in order to intuitively demonstrate the optimality ofthe optimization results, the Pareto points for the case of considering two objectives are shown.