Real-time application of Pontryagin’s Minimum Principle to fuel cell hybrid buses based on driving characteristics of buses

Abstract

The Pontryagin’s Minimum Principle (PMP)-based energy management strategy is regarded as one of the most promising strategies for hybrid vehicles, given that it instantaneously provides optimal power distribution solutions between power sources. The real-time application of the PMP, however, is still difficult due to the heavy computational burden and the uncertainty of the future vehicle driving cycle. The driving characteristics of city buses, including the bus dwell time at bus stops and comparatively specified driving routes, are very helpful when realizing the PMP to hybrid powertrains. An energy management approach of fuel cell hybrid buses for real-time applications is proposed in this research based on the driving characteristics of buses, in which a reference driving cycle (RDC) is defined for a bus driving route and the bus dwell time is sufficiently used to calculate the PMP-based power distribution solutions. In order to reflect the deviation of the real bus driving route from the RDC, the control parameter of the PMP is updated at every bus stop before calculating the solutions. Simulation results show that the power distribution result of the proposed energy management approach reaches that of the offline PMP application and the discrepancy is within 2.65% for the driving cycles studied.