Experimental research and performance analysis of a free piston expander–linear generator coupled with a driving motor

Abstract This paper establishes a test bench for a free piston expander–linear generator (FPE–LG) system coupled with the drive motor (DM) to promote the application of FPE–LG on vehicle. Firstly, it discusses the operating characteristics and output performance of the FPE–LG under the simulated operation conditions of vehicle. Meanwhile, it investigates the operating characteristics of FPE–LG under different torques and expansion times. Finally, this paper analyzes the influence of different torques and expansion times on the operating frequency of FPE–LG. The experimental results show that the operating frequency of FPE–LG is related to the expansion time and torque. The power output of the DM decreases as the torque increases, the power output of the DM increases first and then decreases as the expansion time increases. Therefore, the selection of suitable expansion time under different intake pressure plays an important role in improving the power output of the DM. The maximum of the peak power output of DM is about 25.8 W, when the intake pressure is 4 bar, the expansion time is 30 ms and the torque is 0.00571 N m.