Abstract
In this paper, we propose a novel charge-equalization circuit for series-connected batteries. The circuit is composed of an intermediate resonant energy tank, formed by an inductor and a capacitor, and selection switches connected to each battery. The advantage of the proposed circuit is that an exchange of unbalanced charge can be established between any two batteries via the intermediate energy tank. In addition, more than one adjacent battery can serve as a charge-transference party on either side through proper activation of the associated selection switches. Moreover, by virtue of the resonant tank, zero-current switching can be achieved to significantly reduce the transference losses. A laboratory circuit with a control unit was designed for eight 2.5 Ah lithium iron phosphate (LiFePO4) batteries in series. The test results demonstrate that the proposed charge-equalization circuit can realize charge balance effectively. With the charge-equalization circuit, the worst open-circuit voltage difference can be reduced to less than 20 mV under offline conditions, which helps the batteries operate more efficiently.
Highlights
Rechargeable batteries have become an integral part of our daily life with the advance of information technology [1]
Numerous battery cells are interconnected in series or parallel to comprise a battery pack, which leads to the charge imbalance issue that frequently accompanies interconnected battery packs
The balance circuit idles for 5 s to wait for the battery’s voltage to rebound in order to ensure accurate detection
Summary
Rechargeable batteries have become an integral part of our daily life with the advance of information technology [1]. From the perspective of energy flow between batteries, energy dissipation, energy control, and energy transfer are used to define the charge balance categories shown in Figure 1 [11,12]. The “energy control” scheme “energy dissipation” scheme consumes the excess battery energy in the resistors. The “energy distributes the charging or discharging currents of each battery through the converters according to the control” scheme distributes the charging or discharging currents of each battery through the SOC converters of each battery. The “energy transfer” scheme transfers energy between the unbalanced batteries according to the SOC of each battery. The “energy transfer” scheme transfers energy through the energy storage components to the achieve a storage balanced state. Between the unbalanced batteries through energy components to achieve a balanced state.
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
