Tsai Yu-Ting, Pawar S J, Wang Chi-Chang, Huang Jin H
Bachelor Program in Precision System Design, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan.
Department of Applied Mechanics, Motilal Nehru National Institute of Technology Allahabad, Teliyarganj, Allahabad (UP) 211004, India.
J Acoust Soc Am. 2017 Mar;141(3):1615. doi: 10.1121/1.4976146.
The rapid development of consumer electronics and the extensive use of mobile devices require the ample use of miniature-loudspeakers for audio applications. The demand for better sound pushes manufacturers to design digital signal processing (DSP) chips (smart amplifiers), which in turn could cause unpleasant sound due to distortion and parameter nonlinearity or transducer damage caused by large diaphragm excursion or voice-coil (VC) burn. This article presents a methodology for nonlinear parameter estimation using an inverse method and displacement limiter for large VC displacement-dependent transducer damage prevention. A set of transduction equations is employed to inversely determine parameters using a polynomial expression. The appropriate selection of an objective function incorporating the unknown vector of nonlinear parameters leads to the adjoint problem that requires a gradient solution. A numerical solver is provided to obtain the VC displacement, current, and derivatives using a robust hybrid spline differential method. The dynamic limiter is proposed to control the peak values of the VC velocity so as to limit an excessive displacement which prevents impulsive damage to the receiver and further application of the DSP board. Numerical and experimental results indicate that the proposed method has high efficiency and can be widely used in transducer applications.
消费电子产品的快速发展和移动设备的广泛使用，要求在音频应用中大量使用微型扬声器。对更好音质的需求促使制造商设计数字信号处理（DSP）芯片（智能放大器），而这反过来又可能由于失真、参数非线性或大音膜偏移或音圈（VC）烧毁导致的换能器损坏而产生令人不悦的声音。本文提出了一种使用逆方法和位移限制器进行非线性参数估计的方法，用于防止与大VC位移相关的换能器损坏。采用一组换能方程，利用多项式表达式反向确定参数。结合非线性参数未知向量的目标函数的适当选择会导致需要梯度解的伴随问题。提供了一个数值求解器，使用稳健的混合样条微分方法来获得VC位移、电流和导数。提出了动态限制器来控制VC速度的峰值，以限制过大的位移，从而防止对接收器造成脉冲损坏，并进一步应用DSP板。数值和实验结果表明，该方法具有高效率，可广泛应用于换能器应用中。
