Abstract
Balancing battery cells is a key task for battery management systems (BMS). Imbalances of cells decrease the capacity and lifetime of the battery pack. Many balancing topologies and strategies have been proposed to balance the electric charges among cells and most of the intelligent control strategies select cells (to shuttle charges) by comparing their terminal voltages. However, the nature of battery equalization is to balance the energy stored in individual cells. The measured terminal voltage is just an external characteristic and cannot accurately reflect the state of charge (SOC) of the cell, especially in a noisy environment. Additionally, when the consistencies of cells are very poor, balancing the cells with terminal voltages will lead to serious errors. In this paper, we introduced a novel battery balancing method, in which the charge-balancing criterion was not the cell voltage, but the shuttling capacities among cells. Data stream mining (DSM) technique was used to calculate the shuttling capacities. A single switched capacitor (SSC) based cell balancing topology was used to test the performance of the proposed method. With the obtained summary information, the cells, the sequence, and the quantity of the equalized charge can be decided automatically by the proposed algorithm. The simulation and experiment results have shown that the proposed method was effective and convenient.
Highlights
Nowadays, Lithium-based batteries are becoming the research focus in the area of electric vehicle design because of their high terminal voltage, large energy density and lack of memory effect [1,2,3].To meet the requirements of high voltage and power, they were commonly connected in a string [4].Due to the manufacturing variances, internal impedance variations, different self-discharge rate and thermal difference, cell imbalances are very usual in a pack
There are four kinds of configurations commonly used in this method [29,30]: basic switched capacitor (SC), double-tiered switched capacitor (DTSC), single switched capacitor (SSC), and modularized switched capacitor (MSC)
The shuttling capacity in DS* keeps on increasing and the shuttling capacity balanced by the voltage based strategy keeps on decreasing until an equilibrium point appeared, at which the shuttling capacity produced by the voltage based strategy is equal to the capacity-updating parameter Δ
Summary
Lithium-based batteries are becoming the research focus in the area of electric vehicle design because of their high terminal voltage, large energy density and lack of memory effect [1,2,3]. Battery selection methods are not suitable for dynamically equalizing the cells in charge or discharge processes. The control strategy of battery balancing system selects cells by their voltages or state of charge (SOC). The cell voltage and charge/discharge current were important measurement data, based on which, a complex analysis progress were carried out to estimate the state of charge (SOC) of cells. The measured terminal voltage is just an external characteristic of cell and it cannot accurately reflect its state of charge This is especially important for Lithium-ion batteries, which have flat Open Circuit Voltage (OCV)-state of charge (SOC) charging or discharging curves. We introduce a novel online battery balancing method, in which the charge-balancing criterion was not the cell voltage or state of charge (SOC), but the shuttling capacity. We conclude this paper by highlighting the key contributions of this work
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
