Design of Rotating Nonlinear Pendulum Vibration Absorbers for Electrified Machinery

Abstract Centrifugal pendulum vibration absorbers (CPVAs) are passive devices and a proven technology for reducing torsional vibrations in rotating systems, including helicopter rotors and crankshafts of internal combustion engines. CPVAs consist of pendulums mounted on a rotor, driven by system rotation, and tuned to counteract engine-order fluctuating torques acting on the rotor, thereby smoothing vibrations. In this study, a unifilar CPVA configuration is proposed to address torsional vibrations in electric machines (EMs). A principal challenge in this application is the high-orders of torsional vibration inherent in current EM operation. As order increases, the path radius of curvature that the absorber mass is required to follow (for proper tuning) diminishes, which presents machining challenges. A dynamic model for a unifilar CPVA is developed and then linearized to compute the tuning orders of the system. A quadratic formula is derived whose roots govern the two natural orders of the system and initial results show a desirable large separation between these orders in a prototype design. The developed model will facilitate future simulation studies of the system forced vibration response to characterize the stability and vibration control performance of this design.