Control System to Improve Online Running Time of Canned Motor for Vacuum Pump

In this paper, the factors and influence mechanism that affect the online running time of canned motor for vacuum pump are studied, and the control system to improve online running time of canned motor is designed. First, the disadvantage of the conventional control system of canned motor was revealed, and the power correction module and restarting module were designed based on the equivalent circuit. Secondly, the methods of determining the angle deviation between ideal axis and actual axis and restarting with speed were proposed. Finally, the influences of angle of axis deviation on the space current vector, steady current and speed were analyzed, and the system designed in this paper can eliminate those influences. The research showed that the distortion of space current vector, steady current and speed ripple increases with the increase of the angle of axis deviation. The experimental platform was established and the test data were in good agreement with the theoretical data, which improved the control accuracy, restrained the speed ripple, reduced the steady current and loss of the motor, reduced the average current by 50% at restarting stage, and verified the robustness of the control system. The research could provide some useful conclusions for the research of the canned motor for vacuum pump.