Fourier Series Analysis Applied in Linear Compressor Vibration Analysis

Linear compressor technology employed in refrigerator shows more energy-saving potentiality, for its compact design, high efficiency and excellent variable cooling capacity. The linear compressor is designed in resonance condition to reduce the input current required, so the dynamic parameters identification for linear compressor would make a positive contribution to a better performance prediction and efficiency operating. While the valves' motion coupled with the free piston structure in linear compressor, which make the gas force is nonlinear and harmonic distortion. It caused the dynamic parameters of linear compressor time varying and nonlinear. Hence the natural frequency estimation seems an impractical task in time domain due to the nonlinear gas force. As the linear oscillating motor has an ability of restricting high harmonics, the natural frequency estimation in frequency domain is practicable. In this paper, we generalize the Fourier Series Analysis applied for linear compressor vibration analysis, including the application for the gas force linearization, the signal processing and the natural frequency estimation. We established a test bench in a refrigerator control system with Fourier Series Analysis for the signal processing and the natural frequency estimation. The effective voltage, the effective current and the power measured by discrete Fourier transform (DFT) method agree well with the results measured by an electricity parameter meter, and the linear motor efficiency achieves a value of 95% in the refrigerator by tracking the nature frequency estimated in frequency domain.