Enhanced sensorless position measurement and control of linear oscillatory motors using novel fractional-order terminal sliding mode observers

Abstract This study introduces a novel sensorless position measurement and control scheme for linear oscillatory motors in linear compressors, leveraging a high-order generalized integrator (HOGI) integrated with a fractional-order terminal sliding mode observer (FOTSMO). Traditional position estimation methods have shown limitations in accuracy due to direct current (DC) offsets and residual harmonics, leading to inefficiencies in maintaining optimal operational states. The proposed HOGI addresses DC component rejection while enhancing signal smoothness, effectively minimizing amplitude and phase distortions. The FOTSMO employs a fractional-order sliding surface to process voltage and current signals, significantly reducing high-frequency noise from back electromotive force. This synergistic approach yields high-fidelity position estimations crucial for precise control and improved tracking of resonant frequencies, validated through dynamic experiments. Results demonstrate the superior performance of the HOGI-equipped FOTSMO, showing enhanced convergence, noise reduction, and robustness under varying stroke conditions. The findings underscore the method’s applicability to other precision-dependent systems, positioning it as an innovative solution within the fields of engineering and measurement technology.