Integrated optimal control of transmission ratio and power split ratio for a CVT-based plug-in hybrid electric vehicle

• Published in: Mechanism and machine theory Vol. 136; pp. 52 - 71
• Main Authors: Yao, Mingyao, Qin, Datong, Zhou, Xingyu, Zhan, Sen, Zeng, Yuping
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2019
• Subjects: Convex optimization; Energy management; Gearshift; Hybrid electric vehicle; Power split; Real-time optimal control; Gearshift; Real-time optimal control; Hybrid electric vehicle; Convex optimization; Energy management; Power split
• ISSN: 0094-114X; 1873-3999
• DOI: 10.1016/j.mechmachtheory.2019.02.014

This study proposes a modeling method for optimal real-time control of a continuously variable transmission (CVT)-based plug-in hybrid electric vehicle (PHEV), which is designed to solve a highly coupled nonlinear optimization problem namely the control of the transmission ratio (TR) and the power split ratio (PSR). Power transmission and power consumption models were first established by carefully introducing convex approximations and relaxations of the powertrain components. Then, the minimum equivalent fuel consumption problem was formulated and converted to a standard convex quadratic programming (QP) problem. Based on the QP modeling method, the equivalent consumption minimization strategy (ECMS) was proposed and verified by hardware-in-the-loop tests, computational efficiency simulations, and performance simulations. The results obtained indicated that the computational efficiency and effectiveness of the QP-based modeling method are high enough to be applied to real-world vehicle controllers, and the fuel economy can be improved significantly as compared to an ECMS without integrated optimization. It was concluded that the QP-based modeling method has high practical value and broad prospects for application to real-time optimal control.