Electric-propulsion systems for ships, also known as electric propulsion devices, represent the current direction of development for maritime power. Issues concerning the environment and fuel economy have compelled the maritime transport sector to seek solutions that reduce emissions and improve fuel efficiency. In this process, power electronics technology plays a significant role in the propulsion systems of ships. Selecting an efficient battery system is of great importance for enhancing the cruising range of yachts and minimizing environmental impact. The battery model is crucial for revealing the working principles of batteries, and it is extremely critical for the application and development of battery technology. The Battery Management System (BMS) serves a crucial regulatory function, optimizing both the safety and performance of battery cells. Central to its operation is the precise estimation of the battery's State of Charge (SOC), a process dependent on an exacting battery model. This system not only enhances longevity and reliability but also ensures that energy storage solutions meet high standards of efficacy. This study focused on testing the impedance characteristics of lithium-sulfur batteries (LSB) at various SOC points and establishing first- and second-order RC equivalent circuit models. The model parameters were identified through experimental data. Subsequently, a simulation platform was constructed using MATLAB/Simulink to simulate the behavior of LSB under a constant current discharge condition. The simulation results showed that the second-order RC model had significantly lower errors than the first-order model, demonstrating higher accuracy. These achievements can provide technical support for the research of energy storage systems in the green aviation and maritime industries.

To study the impedance characteristics of a fluorescent OLED according to the device structure, we fabricated Device 1 using ITO / NPB / Alq3 / Liq / Al, Device 2 using ITO / 2-TNATA / NPB / Alq3 / Liq / Al, and Device 3 using ITO / 2-TNATA / NPB / SH-1:BD / Alq3 / Liq / Al. The current density and luminance decreased with an increasing number of layers of the organic thin films in the order of Device 1, 2, 3, whereas the current efficiency increased. From the Cole-Cole plot at a driving voltage of 6 V, the maximum impedance values of Devices 1, 2, and 3 were respectively 51, 108, and 160 Ω just after device fabrication. An increase in the impedance maximum value is a phenomenon caused by the charge mobility and the resistance between interfaces. With the elapse of time after the device fabrication, the shape of the Cole-Cole plot changed to a form similar to 0 or a lower voltage due to the degradation of the device. As a result, we were able to see that an impedance change in an OLED reflects the characteristics of the degradation and the layer.

In the present study, impedance characteristics for AgO-Zn cell at various State-of-Charge (SoC) has been studied. The impedance measurements of AgO-Zn cell at various SoC were made over the frequency range from 100kHz to 10mHz with an amplitude 5mV. The impedance parameters have been evaluated by the analysis of the data using an equivalent circuit and a Non-linear least squares (NLLS) fitting method. The total resistances reflects the SoC of the cell. This indicates that the total resistance is important parameter for predicting SoC of AgO-Zn cell.