A Fast Charging Balancing Circuit for LiFePO4 Battery

Abstract

In this paper, a fast charging balancing circuit for LiFePO4 battery is proposed to address the voltage imbalanced problem of a lithium battery string. During the lithium battery string charging process, the occurrence of voltage imbalance will activate the fast balancing mechanism. The proposed balancing circuit is composed of a bi-directional converter and the switch network. The purpose of bi-directional is that the energy can be delivered to the lowest voltage cell for charging mode. On the other hand, the energy stored in the magnetizing inductors of the transformer can be charged back to the higher voltage cell in recycling mode. This novel scheme includes the following features: (1) The odd-numbered and even-numbered cells in the string with the maximum differential voltage will be chosen for balancing process directly. In this topology, there is no need to store and deliver the energy through any intermediate or the extra storing components. That is, the energy loss can be saved to improve the efficiency, and the fast balancing technique can be achieved. (2) There is only one converter to complete the energy transfer for voltage balancing process. The concept makes the circuit structure much simpler. (3) The structure has bi-directional power flow and good electrical isolation features. (4) A single chip controller is applied to measure the voltage of each cell to achieve the fast balancing process effectively. At the end of the paper, the practical test of the proposed balancing method on LiFePO4 battery pack (28.8 V/2.5 Ah) is verified and implemented by the experimental results.

Power Converters in Power Electronics: Current Research Trends

“…Various power converter topologies for different applications, such as wireless power transfer [25,26], battery charging [27,28], static synchronous compensator (STATCOM) [29], and gate driver [30] are presented in this issue. In Reference [24], an inductive power transfer (IPT) system with three-bridge switching compensation topology is proposed, to achieve the load-independent constant current (CC) and load-independent constant voltage (CV) outputs.…”

“…A fast-charging balancing circuit for LiFePO4 battery is proposed in [26], to address the voltage imbalanced problem of a lithium battery string. In Reference [27], an add-on type pulse charger is introduced, to shorten the charging time of a lithium ion battery. In Reference [28], an individual phase full-power testing method for high-power STATCOM is presented with reconfiguration the port connection of three-phase STATCOM.…”

Designing High-Voltage and Large-Capacity Battery Packs for Fuel-Cell Hybrid Railroad Propulsion System

“…The operation characteristic of having no rest time of the battery packs adversely affects the lifetime of the batteries [12]. Under these conditions, applying the appropriate cell-balancing technology becomes more important to enhance the safety of the battery pack and to secure the life expectancy of the battery pack [13,14].…”

A Non-Dissipative Equalizer with Fast Energy Transfer Based on Adaptive Balancing Current Control

“…Cell equalization is an effective way of compensating for weak cells and providing safer pack solutions to extend battery run time and lifespan as well. In the last decade, considerable balancing architectures with various balancing strategies have been proposed in the literature [15][16][17][18][19][20][21] to solve the problem of cell imbalance. Based on the energy transfer manner, the equalizer is divided into passive and active types [22][23][24].…”

“…In addition, based on the energy transfer mode, the realizable ways for active equalizers include capacitive, inductive, and transformer-isolated types [25,26]. Namely, it can be subdivided into switched-capacitor (SC)-based [27,28], converter-based [16][17][18][19], and transformeror inductor-based [20,21,29,30] solutions. Active balancers reach cell equilibrium by transferring energy from higher voltage cell(s) to the lower one(s), which can obtain fast and efficient balance compared with passive counterparts at the expense of bulky size as well as high control complexity and cost.…”