Abstract
In this study, an active inductive equalizer with fast energy transfer based on adaptive balancing current control is proposed to rapidly equilibrate lithium-ion battery packs. A multiphase structure of equalizer formed by many specific parallel converter legs (PCLs) with bidirectional energy conversion serves as the power transfer stage to make the charge shuttle back and forth between the cell and sub-pack or sub-pack and sub-pack more flexible and efficient. This article focuses on dealing with the problem of slow balancing rate, which inherently arises from the reduction of balancing current as the voltage difference between the cells or sub-packs decreases, especially in the later period of equalization. An adaptive varied-duty-cycle (AVDC) algorithm is put forward here to accelerate the balance process. The devised method has taken the battery nonlinear behavior and the nonideality of circuit component into consideration and can adaptively modulate the duty cycle with the change of voltage differences to maintain balancing current nearly constant in the whole equilibrating procedure. Test results derived from simulations and experiments are provided to demonstrate the validity and effectiveness of the equalizer prototype constructed. Comparing with the conventional fixed duty cycle (FDC) method, the improvements of 68.3% and 8.3% in terms of balance time and efficiency have been achieved.
Highlights
Groups of battery cells arranged in connection of series and/or parallel to constitute a battery energy storage system (BESS) have been widely used in many emerging industrial applications, such as all kinds of renewable energy generation systems and various types of electric vehicles (EVs), in which there is a need to fill the requirements for high power and/or high voltage [1,2,3,4]
The strict battery screening process [9] is usually done by manufacturers to sort cells with similar state of charge (SOC) by the test of open circuit voltage (OCV) when making multi-cell packs
The studied multiphase of equalizer formed by many specific parallel converter legs (PCLs) with bidirectional energy conversion serves as the power transfer stage to make the charge shuttle back and forth between the cell and sub-pack or sub-pack and sub-pack more flexible and efficient
Summary
Groups of battery cells arranged in connection of series and/or parallel to constitute a battery energy storage system (BESS) have been widely used in many emerging industrial applications, such as all kinds of renewable energy generation systems and various types of electric vehicles (EVs), in which there is a need to fill the requirements for high power and/or high voltage [1,2,3,4]. A modern BESS must be equipped with a reliable and effective battery management system (BMS) to ensure that the BESS itself and its powered loads can work normally and safely [5,6]. The strict battery screening process [9] is usually done by manufacturers to sort cells with similar SOCs by the test of open circuit voltage (OCV) when making multi-cell packs. Battery inconsistencies usually reveal a mismatch in internal resistance, voltage, or capacity imbalances after charging and discharging cycles [12,13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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
