基于分时驱动方法压电堆响应速度的研究

发布时间：2018-03-02 06:32

本文关键词： 压电驱动器响应速度分时驱动应力波 COMSOL Multiphysics　出处：《中国科学技术大学》2016年硕士论文　论文类型：学位论文

【摘要】：快速响应是压电驱动器最主要的优点之一,目前关于压电驱动器的研究都是基于同时驱动结构即同时激励压电堆中所有的压电层。这种驱动结构是将压电堆看作一个整体,忽略了在高频驱动时压电堆内部应力波传播对压电堆输出的影响。针对这一问题,本文创新性的提出了一种分时驱动方法,它通过考虑压电堆中应力波传播规律,分时依次地激励压电堆中各压电层,使各层产生的应力波同时传播到压电堆顶端实现线性叠加,从而大幅度提高压电堆的响应速度。本文对压电堆中应力波波动方程、传播规律等进行了理论推导和分析,并利用有限元仿真软件COMSOL Multiphysics构造压电堆模型、分时激励脉冲序列,对分时驱动思想进行验证。首先分别仿真了将压电堆底面直接刚性固定时,其在同时驱动和分时驱动方法下的动态响应输出,仿真结果显示此时分时驱动下压电堆的响应速度并未得到很好的改善；通过对分时驱动下压电堆的响应曲线进行分析得出：由于压电堆产生的下行波未经过线性叠加,它们经过底面反射后会重新传播到压电堆顶端,从而影响分时驱动的效果,延长压电堆的响应时间。为了验证这一结论,我们在压电堆底面增加一无限长的压电杆基座,用它来吸收压电堆的下行波,仿真结果证明此时分时驱动下压电堆的响应速度是同时驱动方法下的2.75倍,分时驱动思想得到了验证。另外我们对基座也做了进一步的选择与优化,设计了更符合要求的基座材料和尺寸。为了通过实验验证分时驱动思想,本文利用压电陶瓷圆环构造了可以被分时驱动的压电堆结构,并利用低压控制高压的思想设计了能产生一系列相邻脉冲间具有可调延时的脉冲序列,它们都具有非常短暂的上升沿,然后利用PVDF压电薄膜对压电堆的动态响应进行测量。实验结果证明,分时驱动方法下压电堆的响应速度是同时驱动下的2.67倍,且分时驱动方法实现了压电堆中各压电层产生应力的线性叠加。因此,分时驱动方法下压电堆的响应速度不随压电堆中被激励压电层数量的变化而改变,也不受激励电压幅值的影响。通过本文所提出的分时驱动方法,可以使压电堆在输出足够大位移的同时还具有非常快的响应速度,对提高压电堆的性能和其在高速驱动下的应用都将发挥重要的作用。
[Abstract]:Fast response is one of the most important advantages of piezoelectric actuators. At present, the research of piezoelectric actuators is based on simultaneous actuating structures, that is, simultaneously exciting all piezoelectric layers in piezoelectric stacks. The effect of stress wave propagation on the output of piezoelectric reactor is neglected when the piezoelectric reactor is driven at high frequency. In this paper, a time-sharing driving method is proposed, which considers the propagation law of stress wave in piezoelectric reactor. In this paper, the stress wave generated by each layer of the piezoelectric reactor is excited in turn, and the stress wave propagates to the top of the piezoelectric reactor to achieve a linear superposition at the same time, thus greatly increasing the response speed of the piezoelectric reactor. In this paper, the wave equation of the stress wave in the piezoelectric reactor is studied. The propagation law is theoretically deduced and analyzed, and the piezoelectric reactor model is constructed by using the finite element simulation software COMSOL Multiphysics, and the time-sharing excitation pulse sequence is obtained. The idea of time-sharing drive is verified. Firstly, the dynamic response output of piezoelectric reactor is simulated under the condition of simultaneous driving and time-sharing drive, respectively, when the bottom surface of piezoelectric reactor is directly rigidly fixed. The simulation results show that the response speed of piezoelectric reactor driven by time-sharing has not been improved very well, and by analyzing the response curve of piezoelectric reactor driven by time-sharing, it is concluded that the downlink wave generated by piezoelectric reactor has not passed through linear superposition. They repropagate to the top of the piezoelectric reactor after reflection from the bottom, which affects the time-sharing driving effect and prolongs the response time of the piezoelectric reactor. To verify this conclusion, we add an infinite piezoelectric pole base to the bottom of the piezoelectric reactor. It is used to absorb the downlink wave of the piezoelectric reactor. The simulation results show that the response speed of the piezoelectric reactor driven by the time-sharing method is 2.75 times that of the simultaneous driving method. The idea of time-sharing drive has been verified. In addition, we have also made further selection and optimization of the base, designed more suitable materials and dimensions of the base. In order to verify the time-sharing drive idea through the experiment, In this paper, a piezoelectric stack structure which can be actuated by time sharing is constructed by using a piezoelectric ceramic ring, and a series of pulse sequences with adjustable delay between adjacent pulses are designed by using the idea of low voltage control high voltage. They all have very short rise edges, and then measure the dynamic response of piezoelectric stacks by using PVDF piezoelectric films. The experimental results show that the response speed of piezoelectric stacks driven by time-sharing method is 2.67 times faster than that under simultaneous actuation. The time-sharing driving method can achieve the linear superposition of the stress of each piezoelectric layer in the piezoelectric stack. Therefore, the response speed of the piezoelectric stack does not change with the number of excited piezoelectric layers in the piezoelectric stack. The time-sharing driving method proposed in this paper can make the piezoelectric pile with large enough displacement and very fast response speed. It will play an important role in improving the performance of piezoelectric reactor and its application in high speed drive.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH703

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