Enhanced Battery Power Constraint Handling in MPC-based HEV Energy Management: a Two-phase Dual-model Approach

This paper presents a novel two-phase dual-model approach to more appropriately handle battery power constraint in MPC-based HEV energy management. The approach fuses two typical battery models with different fidelities in two consecutive phases of MPC’s prediction horizon, where more accurate 1st order resistor-capacitor (RC) model is adopted in the near phase while a purely ohmic impedance model is used in the more distant phase. More importantly, it is mathematically rigorously proven that the 1st order RC model can be reformulated as an equivalent single-state model while preserving accurate voltage calculation provided the length of phase one is properly determined. Finally, the formulated optimal energy management problem is solved using a forward dynamic programming algorithm. Both numerical examination and MiL test using an experimentally validated forward-facing simulator demonstrate that compared with traditional approach, the proposed approach can achieve better optimality in the condition of very sparse state discretization which is imperative for real-time implementation.