A Double-Sided Flat Permanent Magnet Linear Motor with Dual Halbach for Free-Piston Linear Generator

Free-piston linear generator (FPLG) is regarded as a promising power generator system for hybrid electric vehicle. The core component of FPLG, linear motor, requires careful design to match the system performances. In this paper, for required performance, a novel double-sided flat permanent magnet linear motor with dual Halbach is proposed. This motor is composed of four modular unit stators on both sides of the mover. Fractional-slot (7-poles/6-slot) and concentrated windings are adopted to each unit for high power, low thrust ripple. The relationship between the linear motor performance and structure parameters is developed and applied to design the size of linear motor. To verify the design of this motor, the two-dimensional finite-element model is established. The feature of output power in motoring and generating model are analyzed. In addition, a prototype is developed and tested in an experimental platform, which consists of rotating electrical machine and crankshaft connecting rod system. In terms of system output power, the experimental data is in well agreement with the finite-element results.