Robust Speed Synchronization Control for an Integrated Motor-Transmission Powertrain System with Feedback Delay 2019-01-1206
Motor speed synchronization is important in gear shifting of emerging clutchless automated manual transmissions for electric vehicles (EV) and other kinds of parallel shaft-based powertrains for hybrid electric vehicles (HEV). Difficulties of the motor speed synchronization problem mainly come from random delay induced by network communication and unknown load torques from air drag, oil drag, and friction torques, etc. To deal with these factors, this paper proposes a robust speed synchronization controller based on act-and-wait control and disturbance observer. The former is a kind of periodical controller specially for regulating problems with feedback delay while the latter is a technique for active disturbance rejection.
Firstly, the dynamic model of the motor shaft is formulated, and the system parameters are offline identified. The speed tracking problem is then transformed into a regulating one. The act-and-wait control law for the nominal model is proposed regarding the new model after transformation. Determination of the feedback gain and its relationship with the speed synchronizing process are discussed. After derivation of the nominal controller, a time-domain disturbance observer is integrated to enhance robustness.
Effects of different feedback gains and observer gains are studied through simulation. Experiments are carried out on an integrated motor-transmission powertrain system, which integrates a traction motor and a dual clutch transmission. Comparisons with the conventional PI controller are carried out regarding transient responses and robustness. Results show that the propose controller is able to achieve both a fast and smooth synchronization process, while the PI controller is faced with the dilemma between overshoot and settling time which cannot be simply solved through parameter adjusting. In conclusion, the proposed disturbance observer-based act-and-wait controller is more suitable for motor speed synchronization control in powertrains for EV and HEV.