Engine automatic start–stop dynamic analysis and vibration reduction for a two-mode hybrid vehicle

Abstract

Hybrid electric vehicles are an effective solution for reducing pollution and improving the fuel economy. Their control strategy often makes the vehicle control unit shut down and restart the internal-combustion engine for better fuel consumption. Starting and stopping the engine can cause driveline vibration, which is easily passed to the driver through the vehicle structure, causing ride discomfort. This research simulates the neutral start and stop of a two-mode hybrid system and correlates this with hardware tests. It investigates a pulse cancellation algorithm to cancel undesired vibration and to smooth ripples in the engine speed during automatic start–stop transitions. Electric motors provide torque to cancel unwanted torque impulses from uneven automatic starts or stops. This study also investigates the damper-bypass clutch. The results show that using pulse cancellation and the damper-bypass clutch can significantly reduce the reaction torque acting on the engine block and vibration of the seat track during automatic start–stop transitions.