Experimental Investigation of Series and Parallel Drive Characteristics in an Opposed-Piston Linear Compressor for Attitude-Following Heat Pumps

Linear compressors eliminate the slider-crank mechanism and facilitate oil-free operations. Self-lubricating opposed-piston linear compressors are suitable for integration into attitude-following heat-pump systems while significantly enhancing the system flow rate. In this study， a dual-motor self-lubricating opposed-piston linear compressor prototype was developed， and a comprehensive test bench was established. Using the R1234yf refrigerant， variable-capacity experiments were conducted to analyze the dynamic responses under series and parallel power supply modes. The results indicate that parallel drive requires a lower voltage than series mode， reducing the voltage differential required to achieve synchronized piston strokes in opposing configurations. During 62 Hz operation， when the supply voltage increased from 120 to 160 V， the series mode maintained， on average， a 0.17 higher power factor and 8.1% greater motor efficiency compared with the parallel mode. Thus， the driving mode selection should consider the specific application requirements.