Stroke Estimation for Linear Compressor with Energy Method

Linear compressor employed linear motor driving the piston directly oscillating in cylinder, shows higher energy efficiency applied in refrigerator. And it also owns excellent variable cooling capacity with piston stroke adjustment. The stroke, or the peak to peak value of piston displacement, have a strong impact on the capacity of linear compressor as well as the efficiency. While collision may arise between piston and cylinder, if the operating condition changes without stroke control. Thus, the stroke is important parameter for linear compressor control. In this paper, an energy method for the stroke estimation is proposed, which omits the displacement sensor. And an experimental platform of the refrigerator stroke control system with PID algorithm is established employed energy method. The electrical parameters of linear motor are used for the stroke estimation. The estimated stroke results are verified with the measured stroke, and the errors would be achieved within ± 5% under different working condition. The method of stroke control for linear compressor startup process is investigated, and a segmentation stroke control could decrease the risk of collision between the cylinder and the piston when the linear compressor startup with pressure varying dramatically.