Piezoelectric ultrasonic motors usually are operated in the vicinity of a resonance of the mechanical oscillations of the stator. The stator is exited by ultrasonic, high-voltage signals provided by the power supply. In order to achieve a good power flow into the motor, the electrical system has to be tuned to the mechanical system. Often the electrical power supply is designed as a two-phase inverter using a series inductor in each branch, such that a resonant converter topology is achieved. If additionally the inductance is matched to the capacitance of the piezoceramics an optimal electro-mechanical coupling results. Mathematical models of the stator, which were obtained by the finite-element method and models of the power supply have been implemented using the multilevel simulator SABER and were used to optimize the overall system behavior.
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