Hybrid automata of an integrated motor-transmission powertrain for automatic gear shift

This paper presents a scheme of hybrid modeling of an integrated motor-transmission powertrain, which is increasingly applied to electric vehicles. The shift process of this system is special due to the absence of clutch, and the mode switch of the propulsion motor increases hybrid characteristics. After the introduction of a definition of hybrid automaton and the analysis of shift process, a motor automaton and a gearbox automaton are developed. Properties under different states and switch conditions are presented in detail. Then a completed integrated powertrain automaton is proposed to describe all possible shift actions. Simulation models are developed to verify the effectiveness of the proposed modeling scheme. The results show that all the continuous states and discrete states as well as transients are fully presented, and thus the shift process is clearly reproduced, which is very useful for the design of controllers to achieve a better vehicle performance.