On real-time optimal control of a series Hybrid Electric Vehicle with an ultra-capacitor

To design a supervisory plan for a Hybrid Electric Vehicle (HEV), different methods are presented in the literature. In many of these controllers, there are a few parameters that must be tuned according to future driving conditions. To address this issue, a novel feedback controller is introduced in this paper that serves as the supervisory plan of a series HEV, and does not require the exact knowledge of the drive cycle. To find this controller, first a mathematical model of the hybrid drivetrain is developed, then Pontryagin´s Minimum Principle is applied assuming that the drive cycle is known in advance. Based on the mechanism of the optimal control, a set of mathematical rules is extracted, and an optimal feedback controller is designed. It is also shown that a priori knowledge of the future drive cycle is not required; it is possible to tune the controller parameters, knowing only the cruise time and the available negative energy during braking.