Closed-Loop Haar Wavelet Power Splitting Method for Vehicle-Mounted Hybrid Energy Storage System

Hybrid energy storage systems are widely used in electric vehicles and other fields. Focused on the problem of lithium-ion battery life attenuation caused by high-frequency components in load power requirements, a closed-loop Haar wavelet power splitting method is proposed. First, the circuit structure of the hybrid energy storage system is introduced. Then, based on the analysis of the Haar wavelet transform, the Haar wavelet power splitting method, and closed-loop control algorithm are proposed. On one hand, the Haar wavelet power splitting method is responsible for allocate the high-frequency and low-frequency components of the power demand to ultra-capacitor and lithium-ion battery, respectively; on the other hand, a closed-loop controller is proposed to regulate the output current of the lithium-ion battery dynamically to maintain the stability of the DC bus voltage. Finally, experiments were conducted under CLTC-P driving cycle. The experimental results show that the proposed closed-loop Haar wavelet power splitting method can control the maximum deviation of DC bus voltage within 1.28%, while effectively avoiding the impact of high-frequency components on the life of lithium-ion batteries. (c) 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Automated summary

In this paper, a closed-loop Haar wavelet power splitting method is proposed to address the issue of lithium-ion battery life attenuation caused by high-frequency components in load power requirements. By allocating the high-frequency and low-frequency components of the power demand to the ultra-capacitor and lithium-ion battery respectively, and dynamically regulating the output current of the lithium-ion battery through a closed-loop controller, the proposed method can effectively control the stability of the DC bus voltage.