For achieving high speed and large thrust, Langevin-type ultrasonic motors (LTUM) are generally operated under high voltage. However, high voltage causes the current harmonics of piezoelectric material nonlinear phenomena, which will decrease the efficiency, the output force, and the accuracy of LTUMs. In this study, the nonlinearity of current harmonics of LTUM are described and analyzed by a novel nonlinear equivalent circuit model using Lagrange equations. Thereafter, based on a nonlinear tuning method, a specific driver circuit is suggested to suppress the current harmonics. Experimental results validate that the time response of the current is consistent with that of the model and furtherly demonstrate that the total harmonic current distortion decreases by 68% utilizing the proposed nonlinear tuning method under 500 Vpp.

为了实现高速和大推力，兰格文型超声马达（LTUM）通常在高压下运行。但是，高电压会引起压电材料非线性现象的电流谐波，这会降低效率，输出力和LTUM的精度。在这项研究中，通过使用Lagrange方程的新型非线性等效电路模型描述和分析了LTUM电流谐波的非线性。此后，基于非线性调谐方法，建议使用特定的驱动器电路来抑制电流谐波。实验结果验证了电流的时间响应与模型的时间响应一致，并进一步证明了在500 Vpp下使用所提出的非线性调谐方法，总谐波电流失真降低了68％。