基于PDC-PMSM的双螺杆泵系统刚度及模态分析

Rigidity and modal analysis of twin-screw pump system based on PDC-PMSM

双螺杆泵、挤压类负载并行对驱机械装备一般采用“异步电机+同步齿轮”驱动,同时螺杆间间距很小,由于系统共振极易造成螺杆碰撞,甚至损坏。针对这一问题,提出了一种并联直驱连体永磁电机直接驱动双螺杆泵的方法,并对其刚度与模态进行了研究。首先,提出了电机的运行机理和设计方法,并对连体电机双螺杆泵系统进行了研究;然后,对其进行了刚度解析计算,得出了总形变量;同时对螺杆和采用连体永磁电机驱动的双螺杆泵系统进行了模态分析,计算了固有频率及相应的临界转速,分析了螺杆的刚度与临界转速能否满足双螺杆泵系统使用要求;最后,制作了样机,并进行了系统稳定性测试。研究结果表明:通过有限元结果验证了刚性解析计算的正确性;同原有驱动方式相比,并联直驱连体永磁电机直驱可有效提升系统效率;设计时通过将电机频率远离固有频率,可以有效防止螺杆的共振,为并联直驱连体永磁电机的速度选择提供参考。

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.