Piezoelectric micro-electro-mechanical-system (MEMS) loudspeakers are attracting growing research interest in the last years due to the increasing interest towards miniaturization required by new wireless audio devices. Finite Element Models (FEM) and Lumped Element Models (LEM) able to accurately simulate their linear response have been recently proposed in the literature. However, a nonlinear model suitable to predict the Total Harmonic Distortion (THD) of these devices is to date still missing. In this work, we present a FEM-assisted lumped-parameters equivalent circuit for THD estimation which accounts for geometric nonlinearities and piezoelectric hysteresis. The loudspeaker nonlinear electro-mechanical domain is simulated through a Reduced Order Model (ROM) which considers as basis function the pre-stressed undamped actuated mode of the device computed via FEM, to account for loudspeaker diaphragms of arbitrarily complex geometry. Parameters of the acoustical circuit are computed through analytical formulas. The good matching between numerical predictions and experimental results, carried out on a piezoelectric MEMS loudspeaker prototype for in-ear condition, demonstrates the accuracy of the proposed tool.

中文翻译：

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通过有限元辅助降阶模型估计压电微机电系统扬声器的总谐波失真


由于新型无线音频设备对小型化的需求日益浓厚，压电微机电系统 (MEMS) 扬声器近年来吸引了越来越多的研究兴趣。最近文献中提出了能够准确模拟其线性响应的有限元模型 (FEM) 和集总元模型 (LEM)。然而，迄今为止仍然缺乏适合预测这些设备的总谐波失真（THD）的非线性模型。在这项工作中，我们提出了一种用于 THD 估计的 FEM 辅助集总参数等效电路，该电路考虑了几何非线性和压电磁滞。扬声器非线性机电域通过降阶模型 (ROM) 进行模拟，该模型将通过 FEM 计算的设备的预应力无阻尼驱动模式视为基函数，以考虑任意复杂几何形状的扬声器振膜。声学电路的参数通过解析公式计算。在耳内条件下的压电 MEMS 扬声器原型上进行的数值预测与实验结果之间的良好匹配证明了所提出工具的准确性。