Optimal Control of Adaptive Mode Transition for Series-Parallel Hybrid Power System

Abstract:

In order to improve the switching quality of the dual-motor electric mode to parallel hybrid mode transition process of a new series-parallel hybrid power system， and ensure the adaptability of the mode switching strategy in different vehicle driving states and driver input， two mode switching control strategies of smooth starting and dynamic starting were proposed. First， the dynamic model of the series-parallel hybrid system was established， and the mode switching process from electric mode to parallel hybrid mode was analyzed to determine the control objectives and control strategies in different stages of mode switching. Then， taking the vehicle driving comfort and engine starting time as the optimization indexes， the optimal engine cranking speed curve was solved through dynamic programming， and an engine starting model predictive optimization control strategy was proposed to calculate the clutch friction torque online. The engine tracked the target optimal speed curve， and the torque fluctuation at the output was compensated by the motor. The results of the simulation and hardware in loop bench test show that the two mode switching control strategies can meet different driving requirements and have good a driving comfort.

Key words:series-parallel hybrid power system;mode transition;model predictive control;engine start