Resonant Energy Carrier Base Active Charge-Balancing Algorithm

Abstract

This paper presents a single LC tank base cell-to-cell active voltage balancing algorithm for Li-ion batteries in electric vehicle (EV) applications. EV batteries face challenges in accomplishing fast balancing and high balancing efficiency with low circuit and control complexity. It addresses that LC resonant tank uses an energy carrier to transfer the voltage from an excessive voltage cell to the lowest voltage cell. The method requires 2N - 4 bidirectional MOSFET switches and a single LC resonant circuit, where N is the number of cells in the battery strings. The balancing speed is improved by allowing a short balancing path for voltage transfer and guarantees a fast balancing speed between any two cells in the battery string, and power consumption is reduced by operating all switches in zero-current switching conditions. The circuit was tested for 4400 mAh Li-ion battery cells under static, cyclic, and dynamic charging/discharging conditions. Two battery cells at the voltage 3.93 V and 3.65 V were balanced after 76 min, and the balancing efficiency is 94.8%. The result of dynamic and cyclic charging/discharging conditions shows that the balancing circuit is applicable for the energy storage devices and Li-ion battery cells for EV.

A Comprehensive Review of Various Topologies and Control Techniques for DC-DC Converter-Based Lithium-Ion Battery Charge Equalization

“…Te ramp converter can work as follows: during the frst cycle, the excess energy can be transferred from the cell to the battery pack through a capacitor and transformer for equalisation. In the second cycle, the power will move from the battery pack to a cell under charge through a transformer and a capacitor [53]. Soft switching is used for all switching devices during turn ON and OFF operations to diminish switching losses and improve efciency.…”