Coupled Modeling and Design Principles of Limited-Angle Vibration Motors for High-Frequency Reciprocating Rotation

In this article, a new type of electric machine called limited-angle vibration motor (LAVM) for the motion of high-frequency reciprocating rotation is proposed. The corresponding coupled model, resonance principle, and design guidelines are established. Contrary to the conventional limited-angle motors, the LAVM mainly utilizes cogging torque within a limited angle and, thus, can be restored as an electromagnetic spring. By proposing the linear torque models, an analytical model coupling the output torque with the mechanical load is derived, which explains the resonance phenomenon occurring in LAVMs, finding that the maximum vibration amplitude and efficiency can be achieved at resonance frequency, and being verified by the field-circuit-coupled finite-element simulation. Guided by analytical results from resonance principles, a design method, supporting matching the motor with target reciprocating frequency and amplitude by designing the key geometry parameters referring to restoring coefficient and electromagnetic torque coefficient aided by finite-element analysis results, is proposed. Furthermore, an improved concurrent design method is presented focusing on the application of LAVMs in the flapping-wing microair vehicle (FWMAV). Finally, validations are conducted through experiments on three prototypes fabricated according to the design principles, and the application feasibility in FWMAV is also provided.