Charging and Discharging Characteristics Analysis of a Battery for a Hybrid Electric Propulsion System

This paper describes a hybrid electric propulsion system consisted of an engine-driven system and an electrically driven system. Generally, small special purpose ships such as coast guard patrol ships and environmental patrol ships are propelled by water-jets driven. If these vessels adopt a hybrid electric propulsion system, they are only propelled by the electric propulsion system using the electric energy stored in the battery in the low-speed operation mode. Therefore these ships can achieve high efficiency, zero emission, and silent navigation in the low speed operation mode. As the electrically driven system is consisted of a rechargeable battery charging pack system and a motor-driven propulsion system, charging and discharging characteristics of rechargeable battery are very important. Hence, we analyzed the charging and discharging characteristics of the battery in detail using the generator system and motor driven system. Especially, the charging efficiency of the proposed rechargeable battery is compared with conventional commercial charging system to reveal feasibility of the proposed system.