A Battery Equalizing Scheme Using Flyback Converter and PhotoMOS Switch

Abstract

This article presents the concept of a series battery balance circuit using flyback converter to implement multiple filling valley balance. The optoelectronic switches are used as the control components for increased safety. Each battery cell has a Photo Metal-Oxide-Semiconductor Field-Effect Transistor (PhotoMOS) switch. The switch is used to determine the time at which the battery cell should be charged. The equalization current can reach 2A, hence the equalization speed is faster. The simulation and experimental results verify the operating characteristics of this proposed topology and method, and show that the circuit is straightforward and has been a low cost implementation.

Battery Equalization by Fly-Back Transformers with Inductance, Capacitance and Diode Absorbing Circuits

“…It also achieves the efficiency around 89% which is higher than the 80% efficiency in [19] and 80.4% in [20]. Furthermore, it can be observed from Figures 15 and 16 that this topology can achieve zero voltage turn off and zero current turn on, thus switching losses will be reduced against those [22][23][24][25][26] where soft switching cannot be achieved.…”

“…C bat,i (SOC e,i − SOC s,i ) (23) where C bat,i is the capacity of cell i. It can be observed that the balancing is finished at about 20 min, so we can take the data at 20 min as the balanced results.…”

“…Though topologies based on transformers have the advantages of high balancing current and efficiency, voltage/current spikes still exist, which will lead to switching losses. For example, [22] proposed a novel inductor-based layered bidirectional equalizer, and [23] used a fly-back converter to implement multiple filling valley balancing. Their equalization speeds were all fast but with high switching losses, thus they have a high requirement for switches.…”