Continuous adaptation of the mechanical resonance frequency of power ultrasonic transducers by switching electrical circuits

通过开关电路连续调整功率超声换能器的机械共振频率

• 批准号: 461995951
• 负责人: Dr.-Ing. Jens Twiefel
• 金额: --
• 依托单位: Institut für Dynamik und Schwingungen (IDS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/461995951?language=en
• 关键词: Continuous; adaptation; mechanical; resonance; frequency

One of the biggest challenges in the production of power ultrasonic transducers is to ensure that the resonant frequency is within a sufficiently small tolerance range. In order to achieve a large vibration amplitude, ultrasonic systems are operated close to or even in resonance. The natural frequency depends on many influencing factors, which can only be controlled permanently to a limited extent. These include ambient conditions, relaxation behavior, degradation of the piezoelectric properties and the process. The typical answer to this problem is to adjust the operating frequency to the changed resonance frequency, which is often a sufficient solution. It becomes a problem, however, if several ultrasonic transducers are mechanically coupled, then an exact tuning is necessary to avoid beating. The solution to operate only one of the transducers resonantly and to "drag along" the others has limitations in power utilization, so the system has to be oversized. With this research project a completely new way will be taken. The piezoelectric coupling shall be used to adjust the resonance, i.e. the frequency at which the highest amplitude per excitation is reached. Thus, the system shall be adapted to the "desired frequency" and not the frequency to the system. Our preliminary work shows that the appropriate electrical circuitry offers this potential. However, so far only the basic feasibility has been shown and the topic has not yet been investigated systematically. In particular, there is no consideration of the interaction with the load of the ultrasonic oscillators. Three methods are to be investigated to change the resonance frequency. (1) Impedance resonance Tuning on Tuning Piezos (ITTP): In addition to the piezo elements used for excitation, "tuning" piezo elements are integrated into the system which are wired with a synthetic impedance. With this impedance, negative capacitances can be realized and thus a large potential useful frequency range can be achieved. (2) Switched resonance Tuning on Driving Piezos (STDP): Since power ultrasound systems are typically operated with switching amplifiers, there are switching pauses in which the terminals of the piezo elements can be short-circuited or isolated. Due to the piezoelectric coupling, the piezo elements exhibit significantly (20%) different stiffnesses in both states. With the ratio the average stiffness can be adjusted. (3) Switched Impedance resonance Tuning on Driving Piezos (SITDP): In the switching pauses, a synthetic impedance is connected to the terminals, thus significantly increasing the insertion range of the STDP method.As a result, it is possible to actively and continuously adjust the system characteristics instead of tracking the excitation to the system.

功率超声传感器生产中最大的挑战之一是确保共振频率在足够小的公差范围内。为了达到较大的振动幅度，超声系统在靠近甚至共鸣中运行。固有频率取决于许多影响因素，这些因素只能在有限的程度上永久控制。这些包括环境条件，放松行为，压电特性的降解和过程。该问题的典型答案是将工作频率调整为更改的共振频率，这通常是一个足够的解决方案。但是，如果将几个超声传感器机械耦合，则成为一个问题，那么需要进行精确调整以避免打击。仅互环共声操作和“拖动”的解决方案的解决方案具有限制，因此系统必须过大。通过该研究项目，将采取一种全新的方法。压电耦合应用于调节共振，即达到每次激发最高振幅的频率。因此，系统应适用于“所需频率”，而不是系统的频率。我们的初步工作表明，适当的电路具有这种潜力。但是，到目前为止，仅显示了基本的可行性，并且该主题尚未进行系统的研究。特别是，没有考虑与超声振荡器的负载相互作用。要研究三种方法以改变共振频率。 （1）在调谐压电（ITTP）上进行阻抗共振调谐：除了用于激发的压电元素外，“调谐”压电元件还集成到系统中，这些元素与合成阻抗有线。通过这种阻抗，可以实现负电容，因此可以实现较大的潜在有用频率范围。 （2）在驾驶压电（STDP）上进行切换共振调节：由于电源超声系统通常使用开关放大器进行操作，因此可以短路或隔离压电元件的端子，在某些停顿中。由于压电耦合，两种状态的压电元件在两种状态的刚度都显着（20％）。随着比率，平均刚度可以调整。 （3）在驾驶压电（SITDP）上进行切换阻抗共振调节：在开关停顿中，合成阻抗与终端相连，从而显着增加了STDP方法的插入范围。结果，结果可以主动，不断地调节系统特征，而不是对系统进行启动。