Suppression of Vibration in PMSM Caused by Time-Varying Load for Reciprocating Compressor

This paper deals with the vibration characteristics of permanent magnet synchronous motors (PMSMs) when there is time-varying load generated in the reciprocating compressor. As the reciprocating mechanism is necessary for compressing the refrigerant, the time-varying load torque is inevitable in compressor. However, this load torque affects to the system dynamics such as the speed fluctuation. These speed ripple cause unexpected vibration characteristics because they induce sideband components in the time harmonics of the electromagnetic force of PMSM. Therefore, we analyzed the vibration characteristics of PMSM according to time harmonics variation and conduct a study to suppress sideband vibration by adopting harmonic current injection method.