Multiphase mixed-integer nonlinear optimal control of hybrid electric vehicles. (January 2021)

• Record Type: Journal Article
• Authors: Robuschi, Nicolò; Zeile, Clemens; Sager, Sebastian; Braghin, Francesco
• Is Part Of: Automatica. Volume 123(2021)
• Publication Date: 2021-01
• Subjects: Hybrid electric vehicles -- Hybrid powertrains -- Energy management -- Nonlinear programming -- Mixed-integer nonlinear optimal control -- Combinatorial integral approximation -- Combinatorial constraints; Automatic control -- Periodicals; Automation -- Periodicals; 629.805
• DOI: 10.1016/j.automatica.2020.109325
• Languages: English
• ISSNs: 0005-1098

Abstract

Abstract: This study considers the problem of computing a non-causal minimum-fuel energy management strategy for a hybrid electric vehicle on a given driving cycle. Specifically, we address the multiphase mixed-integer nonlinear optimal control problem that arises when the optimal gear choice, torque split and engine on/off controls are sought in off-line evaluations. We propose an efficient model by introducing vanishing constraints and a phase specific right-hand side function that accounts for the different powertrain operating modes. The gearbox and driveability requirements translate into combinatorial constraints. These constraints have not been included in previous research; however, they are part of the algorithmic framework for this investigation. We devise a tailored algorithm to solve this problem by extending the combinatorial integral approximation ( CIA ) technique that breaks down the original mixed-integer nonlinear program into a sequence of nonlinear programs and mixed-integer linear programs, followed by a discussion of its approximation error. Finally, numerical results illustrate the proposed algorithm in terms of solution quality and run time.