This paper proposes a model-based lithium-ion battery control strategy designed to prevent excessive battery charging and discharging using the estimated lithiumion concentration profiles. The battery lithium-ion concentration profiles are estimated from the electrochemical model-driven EKF and used in the control design. The EKF is designed using the electrode-averaged electrochemistry model with uneven discretization of the radius of the solid electrode particle for fast and accurate prediction of the lithium intercalation dynamics. The allowable battery power limits are then adjusted through the PI feedback of the weighted average difference between the estimated lithium-ion concentration profile and the bulk lithium-ion concentration. The proposed control strategy is implemented in the simulation of the hybridized heavy-duty series HEV. The simulation framework includes a finely discretized electrode-averaged lithium-ion battery model to capture the terminal voltage of the battery accurately. Although the electrode-averaged model tends to overestimate the lithium-ion diffusion dynamics under high current discharging and charging conditions, the overestimation will be beneficial for control design since it acts as an additional control margin. The proposed strategy successfully prevents over-charging and over-discharging under aggressive driving. Further battery size reduction is obtainable at the expense of the fuel economy. The conscious power management strategy of the lithiumion diffusion dynamics provides more flexibility in determining the battery size with consideration of the fuel economy and the battery cost of series HEVs.
Nonlinear lithium-ion diffusion dynamics conscious power management strategy in hybrid electric vehicles for battery downsizing
2012
12 Seiten, 14 Bilder, 2 Tabellen, 16 Quellen
Article (Journal)
English
Automotive engineering | 2012
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