Integrated performance improvement for a bimodal linear ultrasonic motor using a dual-frequency asymmetric excitation method

To improve the integrated performance of a representative bimodal linear ultrasonic motor under continuous operation, this paper proposes a novel dual-frequency asymmetric excitation method for such motors which can operate under traditional single-phase asymmetric or two-phase symmetric excitation modes. In particular, two optimal excitation frequencies from loss reduction aspect of the stator under actual contact-based operating conditions are determined by the corresponding equivalent circuit model. The effects of the proposed excitation mode on the motion trajectory of the driving tip and the motor performance are analyzed in detail. Both the simulation and experimental results show that the motor has better mechanical characteristics with the proposed excitation method comparing to traditional excitation methods. Furthermore, the experimental results indicate that the motor demonstrates acceptable temperature characteristics and operating stability under the proposed excitation method with calculated optimal frequencies.