To develop theoretical instructions for designing the dive of ultrasonic motor(USM),an equivalent electrical model for the USM was studied. Firstly,the vibration equation of the piezoelectric laminated piezoelectric beams excited by electricity was given, which resulted to a six-side equivalent circuit model for the beam's vibration. Then, taking into account the polarization configuration of the stator of the USM, a distributed parameter circuit network mode was derived for the free stator. Focusing on the stator's vibration in the frequency range near the motor's working modal frequency, with addtions, by modeling the dielectric loss and mechanical loss of the stator, a two-side equivalent circuit model was proposed for the stator. Finally, by taking into account the motor's pre-pressure, load and temperature which greatly influenced the characteristic of the

USM, a complete electrical equivalent model was established for the USM. Experiments

 were made to validate the models. The results show that the experimental values agree

the simulations from the models well, which indicates that the models are available.

首先建立了压电层合梁的压电振动方程，并引入六端等效电路对振动进行描述。再根据电机定子与压电梁的结构对应关系，推导出定子的导纳频响方程，并给出理想定子的等效电路;针对定子在其工作频区的导纳特性，构建出定子的二端等效电路;在对耗损、预压力、负载、温度等因素建模基础上，构建出电机完整的等效电学模型。最后，通过电机扫频试验验证了所建立模型的有效性。

超声电机, 模态振动, 导纳频响特性, 等效电路