Assessing the performance of active balancing methods poses a significant challenge due to the time required to replicate the equalization of various balancing techniques under identical initial cell conditions. Conventional circuit simulation methods, designed for high-frequency switching behavior, impose a considerable computational burden when applied to the long-term equalization of battery cells. To address this challenge, this paper presents an efficient performance evaluation method employing an average equivalent model of the equalizers. By representing the charge transfer mechanism inherent to the equalization process, the proposed approach is compatible with the most widely used switched-energy-tank equalizers. The validity of this method is confirmed through simulation and experimental results. In the case of four series-connected battery cells, our proposed approach can assess the performance of a three-hour equalization process in just one minute of execution time. The use cases in the paper highlight the practical feasibility of the AM in facilitating performance comparisons of SET-Es under various initial conditions.

For the maintenance of electric vehicle batteries, a special apparatus achieving the state-of-charge (SOC) alignment of the whole cells inside a battery pack is highly promising. Specifically, when battery packs are discharged to a safe SOC level before shipping, according to battery logistic policy, and charged back to a nominal SOC level before being replaced in the swapping station, the SOC levels of all cells should be aligned to a specific target level. Conventionally, numerous cell-balancing hardware architectures and control strategies are studied; however, they only equalize the SOC between cells, and a whole pack SOC alignment feature has not been evaluated. In this article, a novel algorithm with a coordinated operation between a pack-charger and cell-equalizer is proposed as a viable SOC alignment algorithm. The full-duplex coordinated strategy, which utilizes a bidirectional pack-charger and cell-equalizer, is proposed for alignment purposes, which can minimize the operating time and the energy loss. The theoretical strategy is investigated to achieve the minimal operation time, and the performance of the proposed method is verified by a hardware prototype for a battery pack with 20-series cells. After the alignment process, the cell SOC levels are equalized within a voltage deviation of 30 mV or SOC deviation of 3%, when the pack SOC level is simultaneously adjusted to a preset level. In comparison with the half-duplex strategy, the proposed strategy has a twice faster processing time, while the energy loss during the process is 38%, 10.4%, and 26.1% lower than before. Otherwise, the proposed strategy achieves higher speed of 52% and 28.9% compared with the conventional strategies in balancing speed comparison.

Energy management systems incorporating battery energy storage systems (BESSs) are an effective way to deal with peak power demand in power systems, contributing to sustainability and energy management. In these systems, BESS interface converters encounter many challenges, such as achieving high efficiency, reliability, and scalability. A partial power processing (PPP) converter is one of the promising methods for reducing system energy losses and increasing reliability, thereby optimizing energy conversion between the BESS and the dc bus. However, implementing PPP in a BESS requires a high input-to-output voltage ratio and bidirectional operation over the battery voltage variation, which increases the design complexity. This paper proposes a half-bridge push–pull converter and provides guidance on its design for that purpose. A design procedure considering system efficiency and operating principles is comprehensively investigated and is applied to a PPP converter operating with a 15 kW BESS. The simulation and experimental results show that the efficiency of the system reaches up to 99% with a converter efficiency of 88%, which shows that the proposed structure achieves bidirectional operation and high efficiency based on the partial power processing concept.