High power density by combining of a double stator and an opposite-magnets linear generator in a dual-type free-piston engine generator

Article type: Research Article

Authors: Sato, Mitsuhide^a; | Nirei, Masami^b | Yamanaka, Yuichiro^a | Bu, Yinggang^a | Mizuno, Tsutomu^a

Affiliations: [a] Faculty of Engineering, Shinshu University, Wakasato, Nagano-city, Nagano, Japan | [b] National Institute of Technology, Nagano College, Tokuma, Nagano-city, Nagano, Japan

Correspondence: [*] Corresponding author: Mitsuhide Sato, Faculty of Engineering, Shinshu University, 4-17-1, Wakasato, Nagano-city, Nagano 380-8553, Japan. Tel.: +81 26 269 5211; Fax: +81 26 269 5215; E-mail: mitsuhide@shinshu-u.ac.jp

Abstract: A linear generator system based on a free-piston engine is expected to be a highly efficient power-generation engine for series hybrid vehicles. However, the engine generator must produce in a limited installation space the very high power required to drive a car. Consequently, considering the car-mounting situation, higher power density is required by means of reduced generator size and higher efficiency. In this paper, a cylindrical double-stator linear synchronous generator with opposing permanent magnets is used for free-piston engine. The double stator realizes smaller size, and using opposing magnets achieves a larger thrust constant than that with a single stator. In a finite-element analysis, the high-efficiency area is expanded compared to a surface-magnet type of the same size. Furthermore, this paper clarifies the effectiveness for improved power density with maximum-generation control in a simulation of a dual-sided engine model.

Keywords: Finite-element analysis, internal combustion engine, permanent magnet machine, power generation control

DOI: 10.3233/JAE-190158

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 2, pp. 355-370, 2021