# COTS Battery Charge Equalizer for Small Satellite Applications
## 2 Study of the Existing Battery Cell Balancing Methods
For instance, in the classical SCE (CSCE), where equalization occurs between adjacent cells, a failure in an equalizing branch renders the process incorrect and can lead \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Balancing Topology Name**} & \multicolumn{2}{c}{**Balancing Method**} & \multicolumn{2}{c}{**Balancing Mode**} & \multicolumn{5}{c}{**Number of Components**} \\ \cline{4-10}  & & & **SWs** & **Rs** & **Ls** & **Cs** & **Ds** & **Ts** \\ \hline FRE & Fixed Resistors & RE & C2R & 0 & \(n\) & 0 & 0 & 0 & 0 \\ \hline SRE & Switched Resistors & RE & C2R & \(n\) & \(n\) & 0 & 0 & 0 & 0 \\ \hline CSCE & Classical SCE [16] & SCE & AC2C & \(2n\) & * & 0 & \(n-1\) & 0 & 0 \\ \hline CSSCE & Chain-Structured SCE [17] & SCE & AC2C & \(2n+4\) & * & 0 & \(n\) & 0 & 0 \\ \hline DTSCE & Double-Tiered SCE [18] & SCE & AC2C & \(2n\) & * & 0 & \(n\) & 0 & 0 \\ \hline DSSCE & Delta-Structured SCE [19] & SCE & AC2C & \(2n\) & * & 0 & \(\
icefrac{\
u_{2}}{\
u}(n^{2}-n)\) & 0 & 0 \\ \hline MSSCE & Mesh-Structured SCE [20] & SCE & AC2C & \(2n\) & * & 0 & \(2n\) & 0 & 0 \\ \hline SPSSCE & Series–Parallel-Structured SCE [21] & SCE & AC2 AC & \(4n\) & * & 0 & \(n\) & 0 & 0 \\ \hline PSSCE & Parallel-Structured SCE [22] & SCE & AC2 AC & \(2n\) & * & 0 & \(n\) & 0 & 0 \\ \hline SSSCE & Star-Structured SCE [23] & SCE & AC2 AC & \(2n\) & * & 0 & \(n-1\) & 0 & 0 \\ \hline SMSCE & Switch-Matrix SCE [24] & SCE & AC2 AC & \(2n\) & * & 0 & 1 & 0 & 0 \\ \hline RSCE & Resonant SCE [25] & RSCE & AC2C & \(2n\) & * & \(n-1\) & \(n-1\) & 0 & 0 \\ \hline SPSRSCE Series–Parallel-Structured RSCE [26] & RSCE & AC2 AC & \(4n\) & * & \(n\) & \(n\) & 0 & 0 \\ \hline PSRSCE & Parallel-Structured RSCE [27] & RSCE & AC2 AC & \(2n\) & * & \(n\) & \(n\) & 0 & 0 \\ \hline SSRSCE & Star-Structured RSCE & RSCE & AC2 AC & \(2n\) & * & \(n-1\) & \(n-1\) & 0 & 0 \\ \hline MFCDE & Multiwinding Flyback CBE [28] & CBE & P2C & 1 & 0 & 0 & \(n\) & \(n\) & 1 \\ \hline SFCBE & Single Flyback CBE [15] & CBE & P2C & \(n\) & 0 & 0 & \(n\) & \(n\) & \(n\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Balancing methods compilation. For the number of components: switches (SW), resistors (R), inductors (L), capacitors (C), diodes (D), and transformers (T). to cell unbalancing. The same issue applies to the chain-structured SCE (CSSCE), the series-parallel-structured SCE (SPSSCE), and the switch-matrix SCE (SMSCE). A similar, though less severe, phenomenon can be observed in the star-structured SCE (SSSCE), the parallel-structured SCE (PSSCE), and the double-tiered SCE (DTSCE), where some failures can be tolerated. However, if an equalization branch breaks into an open circuit, other topologies could continue the equalization process, as seen with the delta-structured SCE (DSSCE) and the mesh-structured SCE (MSSCE). For these reasons, this work focused on two equalizer circuits that were easier to implement from an SPFF perspective: the DSSCE and the SFCBE. The following section details the implementation of these two topologies for further study.