Linear compressors can be used for refrigeration systems due to higher efficiency, oil-freeoperation and compactness. One major challenge for linear compressor is the sensing of pistonposition. This paper presented a novel method to detect the piston position at resonance withouta piston position sensor. Inductive coil was wounded around the middle core and the end core.The peak-to-peak flux linkage at two zero crossing points of measured current was calculated forvarious strokes for resonance operation. The results show that both the peak-to-peak flux linkageof end core and middle core vary linearly with the stroke. A linear function was fitted for peak-topeakflux linkage at various strokes. The maximum error between calculated peak-to-peak fluxlinkage with measured current and linear fitting result is about 6%. When linear compressor isoperated off resonance, the flux linkage difference is smaller than that at resonance. It can beconcluded that inductive coil can be used to detect the compressor stroke thus to modulate thecooling capacity of the refrigeration system.
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