A charging scenario for parallel buck-boost battery power modules with full power utilization and charge equalization

Abstract

This paper proposes a charging scenario of a battery power bank constructed by a number of buck-boost type battery power modules (BPMs) in parallel. With associated power electronic converters, the BPMs in the power bank can be individually controlled. The charging scenario is programmed to fully utilize the available power from the dc source, and at the same time to perform charge equalization during the charging process. To share the available dc power cooperatively, the battery voltages are dynamically monitored to calculate the instantaneous charging power. Accordingly, the battery currents can be scheduled in accordance with their ongoing state-ofcharges (SOCs), which are accumulated by the coulomb counting method. A battery power bank with four parallel buck-boost type BPMs is built. Experiments are conducted to demonstrate the functions of the charging scenario.

Optimal algorithms for the charge equalisation controller of series connected lithium‐ion battery cells in electric vehicle applications

“…Here, I in is the equaliser input current, I out is the equaliser output current, and C is the rated capacity of the 15.5 Ah lithium-ion battery. By solving the above equations, the relationship between the equalisation time T eq and equalisation current I eq can be determined as in (15), which is used to estimate the equalisation time with the nominal current so that the fly-back converter operates at the nominal current with tolerable stresses. The relationship can be simplified for a pack with a large number of lithium-ion battery cells with (16) and 17, where I eq is approximately equal to the equaliser output current I out and T eq is directly related to the SOC and I eq (see (15))…”

“…Comparison of equalisation controllers Type → property↓ SR [11] SC [12] MSC [11] SI [8] MWT [13] MpWT [8] CC [14] BBC [15] RC [8] ReC [16] Proposed equalisation type P A A A A A A A A A A equalisation time S S G H…”

A Battery Power Bank with Series-Connected Buck–Boost-Type Battery Power Modules

“…A battery power bank can be formed by a number of BPMs connected in series or parallel for aggregating higher voltage, power, and energy. With a bidirectional converter, charge equalization can be made during either charging or discharging phases [11][12][13]. A charging scenario based on a constant-current/constant-voltage (CC-CV) scheme has been proposed for the parallel buck-boost BPMs to fully utilize the available power provided by the dc source, which means that the entire charging process can be more efficient [12].…”

“…With a bidirectional converter, charge equalization can be made during either charging or discharging phases [11][12][13]. A charging scenario based on a constant-current/constant-voltage (CC-CV) scheme has been proposed for the parallel buck-boost BPMs to fully utilize the available power provided by the dc source, which means that the entire charging process can be more efficient [12]. During the charging process, the battery charging currents are regulated in accordance with their ongoing SOCs accumulated by the coulomb counting method for alleviating the charge imbalance among batteries.…”

“…This paper focuses on the discharging operation of a battery power bank with bidirectional buck-boost-type BPMs connected in series. A buck-boost converter was able to isolate the exhausted or abnormal battery from the BPM by simply removing the gate signal to the corresponding active power switch without the need for additional devices [12]. A laboratory battery power bank is set up with a proposed discharging scenario to demonstrate the performances of charge equalization, load voltage regulation, and fault tolerance with experimental results.…”