## 5 Conclusions  
In this study, we propose a D-MPC approach to enhance the performance of the inverters used in electric propulsion ships. The proposed method maintains the power quality improvements of the multi-vector MPC while minimizing the switching losses via discontinuous modulation and optimized zero-voltage vector selection. The simulation and experimental results demonstrate the superior performance of the D-MPC method when compared with the conventional MPC and multi-vector MPC approaches.  
The proposed method employs discontinuous switching in high-current regions to reduce the switching losses, and it selects the optimal zero-voltage vector based on the offset voltage polarity to suppress unnecessary switching operations. Using this approach, the proposed method achieves an improved THD performance of up to 30%. The current error is also reduced by 30-45% based on the sampling frequency, with significant improvements observed under lower sampling frequency conditions (5-10 kHz).  
While maintaining a current quality similar to that of the multi-vector MPC, the proposed method achieves substantial loss reductions of approximately 15% when compared with the conventional MPC and 24% when compared with that of the multi-vector MPC. A consistent pattern of lower switching losses and higher inverter efficiency was observed under various switching frequency conditions.  
Furthermore, the D-MPC approach reduces the computational overhead by limiting the number of switching state options via discontinuous interval settings. The DSP execution time of the proposed method decreases by approximately 20% when compared with that of conventional MPC, while maintaining a performance level similar to that of the multi-vector MPC, thereby ensuring the ease of real-time implementation. This ensures the feasibility of real-time implementation.  
The findings of this study present considerable technical advantages for power conversion devices operating in environments with limited cooling systems, such as small- to medium-sized vessels. By simultaneously enhancing the inverter efficiency, control performance, and implementation simplicity, the proposed D-MPC contributes to the advancement of inverter control technology for electric propulsion ships. Furthermore, it presents considerable potential for applications in various industrial fields where power conversion is critical.  
Future plans include long-term performance verification through maritime demonstration on actual small- and medium-sized electric propulsion vessels and the optimization of overall electric propulsion system efficiency through integration with energy storage systems.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Conventional MPC** & **Multi-Vector MPC** & **Proposed MPC** \\ \hline Losses [W] & 307.5 & 344 & 260 \\ Efficiency [\%] & 93.85 & 93.12 & 94.8 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of the losses and efficiency between conventional MPC, multi-vector MPC, and the proposed discontinuous MPC (5 kW).  
**Author Contributions:** Methodology, C.R.; software, E.-c.S.; investigation, H.-g.C.; data curation, E.-c.S.; writing--original draft, C.R. and H.-g.C.; writing--review and editing, C.R.; supervision, C.R.; project administration, C.R. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the Ministry of Trade, Industry and Energy (MOTIE) and the Korea Evaluation Institute of Industrial Technology (KEIT), grant numbers RS-2024-00437087 and RS-2024-00432064.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
**Conflicts of Interest:** The authors declare no conflicts of interest.