An online energy management strategy based on Lagrange multiplier method was proposed in order to generate the optimal energy management for torque coupling based hydraulic hybrid excavator (HHE) system. The system cost function and terminal constraints were formulated, and the load data collected from actual excavator was used as system input. Then the optimization problem was solved using Lagrange multiplier (LM) method to generate the optimal equivalent weight and optimal offline energy management strategy. For real time implementation, an LM based interval sampling moving window method for equivalent weight estimation, as well as an accumulator state of charge (SOC) based modification function, were applied to generate the online adaptive energy management strategy. Results show that the proposed energy management strategy can be used in real time, and is adaptive to the working conditions and accumulator SOC. The online strategy can achieve the same level of fuel economy (18.1%) as deterministic offline optimization．
XIAO Yang, GUAN Cheng, WANG Fei. Energy management strategy for torque coupling based hydraulic hybrid excavator. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2016, 50(1): 70-77.
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