Analysis of nonlinear dynamics in a linear compressor

Abstract

In linear electrodynamic oscillating compressors, gas force has nonlinear characteristics depending on the stroke of piston. Static and dynamic components of the force are coupled to each other. Furthermore, mechanical part is coupled with electromagnetic part. Hence, dynamics analysis of the whole system is very complicated. In this paper, the gas force is represented in terms of equivalent stiffness and equivalent damping by employing the describing function approach so that analysis of steady state response characteristics and jump phenomenon can be done in a way simpler than by the full nonlinear model. In order to illustrate accuracy of the equivalent model, the frequency response characteristics of the proposed model are compared with those of the full nonlinear model. Jump phenomena depending on the amplitude of supply voltage is also investigated by using the equivalent model and the necessary conditions for jump to occur are derived.