Abstract: Twin-screw pump and extrusion load parallel drive mechanical equipment was generally driven by “asynchronous motor +synchronous gear”. At the same time, the distance between the screws was very small, the system resonance could easily cause the screws to collide or even be damaged. Aiming at this problem, a method of directly driving twin-screw pump by parallel direct-driven conjoined permanent magnet synchronous motor (PDC-PMSM) was proposed, and its stiffness and modal were studied. The basic structure and design method of PDC-PMSM was put forward, and the twin-screw pump system with PDC-PMSM was studied. Then the rigidity was analytical calculated and the total shape variable was obtained respectively. The screw and the twin-screw pump system driven by the connected permanent magnet motor were analyzed, the natural frequency and the corresponding critical speed were calculated, and the screw stiffness and critical speed were analyzed to meet the requirements of the twin-screw pump system. Finally, a prototype was manufactured and the system stability test was developed. The results indicate that the correctness of rigid analytical calculation is verified by finite element method (FEM). Comparing with the original drive mode, the direct drive of PDC-PMSM can effectively improve the efficiency of the system. In the design, the resonance of the screw can be effectively prevented by keeping the motor frequency away from the natural frequency and provide a reference to select speed for PDC-PMSM.
Key words:  twin-screw pump;modal analysis;rigidity analysis;parallel direct-driven conjoined permanent magnet synchronous motor(PDC-PMSM)

DAI Si-rui, LI Wei, FENG Gui-hong, et al. Rigidity and modal analysis of twin-screw pump system based on PDC-PMSM［J］.Journal of Mechanical & Electrical Engineering, 2022,39(2):141-149,165.