Electromagnetic Energy Harvester Based on Self-Starting Stirling Engine for Waste Heat Recovery

In this paper, we propose an electromagnetic energy harvester (EMEH) based on a self-starting Stirling engine to recover mid-high temperature waste heat (over 200 °C). The harvester utilizes a gamma-type Stirling engine with a crank-slider structure as the power unit, converting thermal energy into rotational mechanical energy. The electrical energy conversion component consists of a rotating magnet array and a stationary coil array. Furthermore, we design an STM32-based self-starting system capable of monitoring the hot cylinder temperature and the Stirling engine speed, initiating the engine once the target temperature is reached. A prototype using mineral oil combustion as the heat source is fabricated, which can self-start at a hot cylinder temperature of 110 °C and achieve a maximum speed of 750 rpm under stable conditions. The maximum open-circuit voltage is 10.34 V. At a load resistance of 600 Ω, the output power can reach up to 55.87 mW. This study demonstrates the practical feasibility of the EMEH based on a self-starting Stirling engine, providing theoretical and experimental support for advancing next-generation technologies in waste heat recovery.