Powertrain control and evaluation of Hybrid Powersplit Systems

This paper focuses on a method to control an hybrid power-split transmission. The main issue is the multivariable aspect of these systems. From a practical point of view, the control needs to track simultaneously a wheel torque, an engine speed and an electric power target. The approach proposed here is based on a two level control strategy. The first one is a so-called energy management which aims at calculating an optimal set of targets minimizing fuel consumption and deciding to stop or start the engine with a sub-optimal but reasonable method. Given these targets, the second control level aims at controlling the transmission, taking into account inertia in a multivariable way in order to achieve some good tracking and decoupling objectives. Each driving mode has to be considered and corresponds to a specific control requirement. To give more realism to previous papers on this topic, we focus here on the fuel cut-off and start modes which are described in details. To this purpose, an observer based state feedback in described. In the last section, we present simulations results for two power-split transmissions on two different driving cycles. The achieved fuel consumption and the control behavior are presented.