Bond Graph Analysis and Optimal Control of the Hybrid Dual Clutch Transmission Shift Process

In order to meet ever demanding requirements on powertrain efficiency and performance improvement, new concepts of automatic transmissions (ATs) have been introduced recently, including electrified conventional transmissions. A representative example of electrified transmission system is a hybrid dual clutch transmission (HDCT). The paper presents an optimisation-based comparative analysis of gear shift processes of different HDCT configurations and the conventional DCT. The paper first outlines a control-oriented mathematical model of a DCT/HDCT-based powertrain and describes the basic DCT gear shift characteristics. The emphasis is then on HDCT systems, including overview of most common HDCT configurations, bond graph modelling and analysis, and control trajectory optimisation. The bond graph analysis illustrates the possibilities of improving the transmission shift performance by utilising the incorporated electric motor. The analysis findings are then quantitatively illustrated by optimisation results, which point out that a proper electric motor action results in significant improvement of shift quality.