Comparison of decomposition levels for wavelet transform based energy management in a plug-in hybrid electric vehicle

A wavelet transform (WT)-based energy management strategy (EMS) is developed to reduce the damages caused by transient and peak power demands on batteries in plug-in hybrid electric vehicles. A hybrid energy storage system (HESS) consisting of a battery pack, an ultracapacitor pack and two DC/DC converters is established based on MATLAB/Simulink. The WT-based EMS with different decomposition levels is evaluated by using simulation under the New European Driving Cycle (NEDC). Comparison results show that the 3-decomposition-level based EMS is the optimal selection. The developed EMS is further evaluated by using simulation under three typical driving cycles including HWFET, WVUBUS and MANHATTAN. To validate the feasibility of the developed EMS, a hardware-in-the loop (HIL) test bench is constructed to simulate the EMS. The results indicate that the developed WT-based EMS with 3 decomposition levels achieves better accuracy performances.