## 6 Conclusions  
This paper proposes a dual-mode control strategy for addressing the disadvantage of conventional SPS control applied to DAB converters. In dual-mode control, PWM and SPS techniques are combined and switched depending on the load. Under light load conditions, the DAB converter is controlled by the PWM control method. During medium-to-full load conditions, on the other hand, the DAB converter is controlled by the SPS method. The experimental results indicate that the converter can achieve the highest efficiency of 96.267% when operating in the forward power conversion mode (power flow from the high-voltage side to the low-voltage side), and 97.331% when operating in the backward power conversion mode (power flow from the low-voltage side to the high-voltage side). Furthermore, there is no oscillation when switching back and forth between operating modes.  
Conceptualization, J.-M.W. and T.N.T.T.; methodology, W.-Y.C. and J.-M.W.; software, T.N.T.T., W.-Y.C. and J.-M.W.; validation, T.N.T.T., W.-Y.C. and J.-M.W.; resources, J.-M.W.; writing--original draft preparation, J.-M.W. and T.N.T.T.; writing--review and editing, J.-M.W. and T.N.T.T. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Load Condition** & **Proposed** & **Ref. [10]** & **Ref. [12]** \\ \hline Light load (10\% of power rating) & 93.34\% & n/a & approx. 86\% \\ Medium load (50\% of power rating) & 93.04\% & approx. 88\% & approx. 92\% \\ Full load (100\% of power rating) & 92.59\% & approx. 90\% & 93.25\% \\ \hline \hline \end{tabular}
\end{table}
Table 4: Efficiency comparison of the DAB converter with different control strategies in forward power conversion.  
Figure 24: Comparison of the efficiency of the DAB converter using the proposed dual-mode control strategy and a DAB converter using the traditional SPS control strategy: (a) forward power conversion mode; (b) backward power conversion mode.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Item** & **Model No.** & **Parameter** & **Power Loss** \\ \hline Pri. (\(S_{1}\)\(\sim\)\(S_{4}\)) & SCT3080 ALGC11 & \(R_{DS(ON)}=80\) m\(\Omega\); \(C_{iss}=571\) pF; \(C_{ss}=19\) pF & 1.769 W \\ \hline Sec. (\(S_{5}\)\(\sim\)\(S_{8}\)) & IRFP4321 PBF & \(R_{DS(ON)}=12\) m\(\Omega\); \(C_{iss}=4460\) pF; \(C_{ss}=82\) pF & 2.385 W \\ \hline Transformer & PC95 PQ50/50Z-12 & \(P_{CV(T)}=39.810\) W/m\({}^{3}\); \(V_{(eT)}=37.2\times 10^{-6}\) m\({}^{3}\); & 1.499 W \\  & \(R_{Copper(Pi)}=3.35\)\(\Omega\); \(R_{Copper(So)}=0.0155\)\(\Omega\) & & \\ \hline \hline \end{tabular}
\end{table}
Table 5: Power loss calculations for the prototype converter at 100 W.  
**Funding:** This research was funded by the Ministry of Science and Technology, R.O.C., (grant numbers: MOST 110-2622-E-150-002 and MOST 111-2221-E-150-009).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors are grateful for the support of Power Electronics Research Laboratory members during the execution of this study. Further, we would like to express sincere gratitude to all anonymous reviewers for their time and expertise, which significantly improved our paper's academic and professional quality.  
**Conflicts of Interest:** The authors declare no conflict of interest.