In order to solve the problems of wear, lubrication and complex structure of digital oil-free scroll compressor, an oil-free scroll compressor driven by magnetic force is proposed in this paper. The new scroll compressor is driven by electromagnetic force, without anti-rotation mechanism and motor, which reduces mechanical contact, so as to achieve the goal of low wear and oil-free. Back pressure device provides variable axial magnetic force to reduce the vibration of the compressor and ensure that the compressor works under the optimum force. The mathematical model of back pressure device and driving force is established and verified by finite element method. The results are in good agreement. The closed-loop step response of the new compressor is simulated. The gas force is decomposed and analyzed. The analysis, calculation and simulation results show that the back pressure device and the driving device meet the requirements of the compressor.

Traditional scroll compressors are difficult to achieve oil-free operation due to the presence of a high-friction anti-rotation mechanism. This paper proposes a magnetic drive oil-free scroll compressor to solve this problem. Firstly, the structure and principle of this scroll compressor are introduced. Then the finite element analysis of the electromagnetic system was conducted; the dynamics model of the magnetic scroll compressor operating in the uncompressed state was established. Finally, the PID control of the system is performed, and simulations and experiments are carried out. Experimental results: under the 0.05 mm step signal in the X direction, the position response time of the system is 0.1 s, and the angle response time of 0.001 rad is 0.2 s. The results show that the oil-free scroll compressor has good position control response characteristics.

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The conventional scroll compressor cannot run oil-free because of wear and tear and lubrication problems during operation due to some parts, such as anti-rotation devices. The magnetic drive oil-free scroll compressor (MDOFSC) uses a contactless drive method to avoid this drawback. In order to solve the swing problem of the orbiting scroll during the operation of the MDOFSC, decentralized control and centralized control are used to study the trajectory tracking characteristics. Firstly, the structure and working principle of the MDOFSC are introduced, and the system’s magnetic circuit and differential control principle are analyzed. Then, the dynamic model of the MDOFSC under the condition of non-compressed gas is established, and the coordinate matrix decoupling method is used to analyze the relationship between the degree of freedom of the system and the measurement distance of the displacement sensor. Finally, the system is simulated and experimentally studied under centralized PID control, and the experimental comparison study between decentralized control and centralized control is conducted. The results show that centralized control dramatically improves the trajectory control ability of the system.

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