Smooth Shutdown Control Strategy of Hybrid Engines for Commercial Vehicle Hotel Mode

Long-haul commercial vehicles provide the hotel mode with a desirable comfort cabin for drivers to have rest. During this mode, sustainable power requirement on the on-board battery asks for occasional engine-on/off to maintain the battery SOC level, neither deeply charged nor overcharged. With the conventional engine-only-driven powertrains, there is a great challenge to deliver smooth engine on/off processes during the hotel mode in order to maintain the cabin as quiet and vibrationless as possible. But for the electric hybrid powertrain system, such a challenge can be addressed with the involvement of the hybrid motor/generator (M/G) to achieve smooth engine crank and shutdown. Apparently it is feasible to control M/G to mitigate discomfortable vibrations inside the cabin caused by periodic engine shutdowns for recharging the battery. In this paper, a pole placement control (PPC) with application of the hybrid M/G is developed to dampen out this kind of adverse vibrations which are transmitted from engine/gearbox to the cabin through the chassis structure and cabin mounts. More specifically, the PPC uses the motor speed as a feedback control signal to create a desirable motor torque command so that the vibration transmission could be abated. In the end of this paper, field testing data from a prototype hybrid truck will be presented to demonstrate the effectiveness of this innovative PPC strategy.