Disturbance Estimation Approach for minimizing Control Windup in Target Engine Speed Profile on Electrified Powertrains with a Low Voltage Belt Starter Generator and a Disconnect Clutch

<div class="section abstract"><div class="htmlview paragraph">In cost- effective P2 hybrid vehicles with low voltage electric machines connected to the engine, an interesting control problem arises during the transition to a locked driveline state. This occurs when the engine connects to the wheels via a separation clutch. The two primary torque sources, the engine and the clutch, are traditionally imperfect estimators of applied and transferred torques. The Hybrid Supervisor’s feedforward constraints model relies on these imperfect inputs to determine torque and acceleration limits for the engine’s desired acceleration profiles and to specify engine feedforward commands, aiming for synchronization speed. Due to the inaccuracies in the torque estimates of the engine and clutch, the Hybrid Supervisor is susceptible to control windup, increased jerk to the driveline during synchronization, and inaccurate computation of its target acceleration profile, speed, and torque targets for the engine to achieve synchronization speed. This paper presents a disturbance estimation strategy to minimize control windup in the development of the Hybrid Supervisor’s speed trajectory, engine feedforward torque commands, and acceleration commands for transitioning a low voltage P2 Hybrid from EV Mode to Hybrid Mode. Simulation and vehicle results indicating the profiled engine speed remains within +- 5 to 8% of its target with minimal overshoot till we get to synch speed, are provided to demonstrate the strategy’s effectiveness.</div></div>