Performance characteristics around the TDC of linear compressor based on whole-process simulation

A whole-process simulation platform is established for linear compressor to analyze the performance characteristics on different piston displacement conditions from small oscillation without pumping till to rushing out of the top dead center (TDC). The measuring methods of the related parameters in the model are presented and the values of these parameters are obtained from an actual test. The simulated results agreed well with the experimental results under the same working conditions. The errors of the effective voltage, the effective current, the compression efficiency and the phase angle between the current and the displacement were within ±6.9%, ±8.5%, ±6.2% and ±13.4%, respectively. Based on this simulation platform, the performance characteristic around the TDC of the linear compressor on different working conditions is analyzed. The performance comparison on 60 Hz shows that the compression efficiency near to the TDC on 0.7 MPa is higher than that on 0.5 MPa because the phase angle α under that condition is around 90°, but the operation reliability on 0.7 MPa is worse than that on 0.5 MPa because the jump phenomenon happens when the piston displacement goes near to the TDC. The jump phenomenon results in unstable operation as the piston displacement jumps from the position before the TDC to the position after the TDC. According to the simulation on different power frequency, two important performance characteristics are inferred. One is that there is an inflection point in the curve of the phase angle α versus the displacement at the TDC. This characteristic is a good choice for the TDC detection. The other is that the jump phenomenon is prone to happening when there exist different displacement responses on the same voltage value, becoming inconspicuous when the power frequency is decreased and disappearing when the power frequency is increased. Based on this characteristic, the jump phenomenon can be avoided through suitable system configuration and frequency adjustment.