Active vibration control for a free piston stirling engine generator using a voice coil actuator.

This work presents the study of active vibration control for a FPSE/LA engine to ensure a reliable engine operation within a broader range of operation frequencies [50 ± 3 Hz] complying with new regulations. An ATMD is discussed as a potential solution for increasing the operational envelope from original frequency requirements of [50 ± 0.5 Hz] to the new range while maintaining vibration amplitudes below 20 μm. A suitable vibration model of the engine setup is discussed and experimentally validated. The active vibration control for the vibration model is achieved by integrating the model of a current controlled Voice coil Motor (VCM). Zero-placement with relative acceleration/position and optimal linear quadratic control with a state observer were studied and compared in the time and frequency domains. The analysis shows that the active control accomplishes damping of vibration even at higher frequencies that coincide with the resonance of the entire system. A set of specifications were obtained based on actuator parameters such as power consumption, actuator strokes and force. The effect of time delays on the stability with each control strategy was investigated based on the proposed vibration model. Delays were found to affect stability depending on both the control methodology and excitation frequency.