Equivalent Circuit Modeling for V-Shape Linear Ultrasonic Motor

Abstract

This work presented an improved equivalent circuit model (ECM) for a typical V-shape linear ultrasonic motor considering the real contact-based operating condition. A four terminal ECM is used to model the energy conversion of the stator under contact-based operating condition, where a nonlinear RC branch with an adjustable capacitance is included in mechanical branch for capturing the variable contact stiffness under different preloads. The friction drive mechanism is modeled by a thyristor rectifier with RL load to characterize the intermittent contact characteristics in standing-wave ultrasonic motors. The output terminal voltage of the rectifier is used as the input to a RL type ECM of the mover. Finally, the dynamics of the motor including the electrical admittance characteristics of the stator under contact-based boundary, the dead-zone behavior and the transient velocity response were validated and discussed by the proposed ECM.