Development of Tracked Combat Hybrid-Electric Vehicle Hidetaka Taira, Takeshi Yoshikawa, Koki Jumonji Mobility Research Division, Ground Systems Research Center Acquisition, Technology and Logistics Agency, Ministry of Defense of Japan (ATLA-MOD) Sagamihara-shi, Kanagawa, Japan Abstract—Electric power needs are significantly increasing and the vehicular power management system becomes more and more important for combat vehicles. Hybrid electric vehicle technologies are advancing in civilian sectors and military ground vehicles obtain following advantages by implementing hybrid electric drive systems: improvement of acceleration and fuel economy, silent mobility and silent watch capabilities and enhancement of on-board electric power generation. However, to the best of authors’ knowledge, there has been no deployed hybrid military vehicles so far and the availability of hardware related papers is limited in spite of these advantages. This paper shows a system design and details of mobility testing of a Tracked Combat Hybrid Electric Vehicle (T-HEV) for the first time. Basic mobility performances for ground combat vehicles such as acceleration, top speed, gradeability and pivot turn capabilities are evaluated and advantages of a hybrid electric system are discussed. Finally, it was revealed that a series hybrid electrical drive system was applicable to combat type vehicles. Keywords—Hybrid Electric Vehicle, Tracked Combat Vehicle, Acceleration, Top speed, Gradeability, Pivot turn I. INTRODUCTION Electric power needs are significantly increasing and the vehicular power management system becomes more and more important for combat vehicles. Although hybrid electric vehicle technologies are advancing in civilian sectors, the idea of combat vehicles with electric drive systems has also a long history. For example, the Saint-Chamond tank was built in between 1916 and 1918 in France and deployed in the First World War. Germany built and deployed Ferdinand (Elephant) tank in the Second World War [1]. The U.S. also developed T- 23 tank with an electric drive in 1943 and evaluated its performance [2]. However, these pioneering vehicles were driven by DC motors and no traction batteries were employed due to the immaturity of relevant technologies and these programs were eventually abandoned [1,2]. Around 2000s, with the progress in HEV technologies in civilian sectors, the research and development of military HEVs became active again and several countries began HEV development programs such as Future Combat Systems (FCS) and Joint Light Tactical Vehicle (JLTV) in the U.S., Future Rapid Effects System (FRES) in the U.K., and Spliterskyddad EnhetsPlatform (SEP) in Sweden [3-5]. In these programs, both hybrid electric wheeled and tracked vehicles were studied and it was revealed that military ground vehicles obtain following advantages by implementing hybrid electric drive systems: improvement of mobility and fuel economy, silent mobility and silent watch capabilities and enhancement of on-board electric power generation [3,4,6]. However, to the best of authors’ knowledge, there has been no deployed hybrid military vehicles so far and the availability of hardware related papers is limited in spite of these advantages [7-10]. In addition, the evaluation of basic mobility requirements for ground combat vehicles such as acceleration, top speed, gradeability and pivot turn capabilities were overlooked even in these hardware related papers. This paper presents a system design and details of mobility testing of a Tracked Combat Hybrid Electric Vehicle (T-HEV) recently developed by Acquisition, Technology, and Logistics Agency, Ministry of Defense of Japan (ATLA-MOD) for the first time. Mobility performances concerning acceleration, top speed, gradeability and pivot turn capabilities are evaluated on concrete roads and advantages of the hybrid electric system for combat ve