A Modular Active Balancing Circuit for Redox Flow Battery Applied in Energy Storage System

Abstract

To improve the operation performance and energy conversion efficiency of the redox flow battery (RFB), a modular active balancing circuit for redox flow battery applied in the energy storage system is proposed in this paper. Detailed topology description, parameter design, characteristic analysis, operation principle and control strategy of the proposed circuit are presented and discussed in the paper. Different from the conventional battery balancing circuit, the key point of the proposed balancing circuit is that it integrates the circulating pump driving circuit and the state-of-charge (SOC) equalization circuit of the redox flow battery. It uses the energy consumption of the pump driving to balance the SOCs of different battery stacks, which provides a new SOC balancing mechanism for RFB. Based on the proposed circuit, an active balancing control strategy using the time-sharing energy transmission method is proposed, in which the sub-modules of the circuit are alternatively configured in charge-state and discharge-state for absorbing energy or releasing energy to achieve the SOC balancing control for RFB. Compared with the conventional balancing solution or circuit, the proposed modular active balancing circuit simplifies the complexity of the battery management system for RFB, which has the advantages of high efficiency, high reliability, and good scalability. Simulations on Matlab/Simulink and experiments on a downscaled prototype were carried out to verify the feasibility and effectiveness of the proposed circuit and control strategy.INDEX TERMS Redox flow battery (RFB), active balancing circuit, battery management system (BMS), state-of-charge (SOC) balance, capacitive energy transfer.

A Comparative Review of Lead-Acid, Lithium-Ion and Ultra-Capacitor Technologies and Their Degradation Mechanisms

“…LI has lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NMC), lithium polymer (LiPo) and lithium titanate (LTO) [37]; LA has flooded, deep cycle, absorbent glass mat (AGM) and gel [38]; nickel based has nickel metal hydride (NiMH) and nickel cadmium (NiCd) [39]; alkaline has rechargeable and non-rechargeable [40]-these are the more commonly known variations. Zinc-oxide (Zn-O 2 /Zn-air) [41], sodium sulphur (NaS/salt) [42] and redox flow batteries (RFB) [29] form part of the lesser-known battery technology category. Table 1 compares the majority of these battery technologies and is used to create the bar graph shown in Figure 2 This figure compares each individual value from the table with the highest value in that category to provide a clear indication of the frontrunners.…”

Electrical Model of a Membraneless Micro Redox Flow Battery—Fluid Dynamics Influence

“…Several works have addressed the electric characterization of conventional redox flow batteries by proposing different equivalent electrical circuits that match the RFB responses to electrochemical impedance spectrometry [17], [18], [19], [20], [21]. These equivalent circuits consist of a source and a combination of impedances of different types and in different configurations.…”