An inverter-based sensorless controller for free-piston Stirling engines

An inverter based sensorless controller is proposed to regulate the amplitude of a free-piston Stirling engine (Daboussi, Z). By actively limiting the alternator electromotive force to given amplitude, piston over stroke and any undesirable growth in the piston amplitude are prevented. The proposed approach eliminates the need for any tuning capacitors and provides a greater flexibility for controlling the piston amplitude. The proposed approach has been successfully demonstrated using a 350 Watts free-piston Stirling engine.