Piezoelectric Circuit Research Articles

Research and Application of the Piezoelectric Ceramic Ultrasonic Transducer

Ultrasonic transducer is produced by piezoelectric materials, and it can detect some characteristics of a target media by transmitting a certain frequency of ultrasonic signals and receiving the signal containing information of the media. The special properties of piezoelectric ceramic determine that the ultrasonic transducer will have a widely used. This paper mainly studies the characteristics of the piezoelectric ceramic, the parameters and equivalent circuit of the transducer performance, and the liquid concentration detection with the transducer.

Hydroelastic response and energy harvesting potential of flexible piezoelectric beams in viscous flow

Electroactive polymers such as piezoelectric elements are able to generate electric potential differences from induced mechanical deformations. They can be used to build devices to harvest ambient energy from natural flow-induced deformations, e.g., as flapping flags subject to flowing wind or artificial seaweed subject to waves or underwater currents. The objectives of this study are to (1) investigate the transient hydroelastic response and energy harvesting potential of flexible piezoelectric beams fluttering in incompressible, viscous flow, and (2) identify critical non-dimensional parameters that govern the response of piezoelectric beams fluttering in viscous flow. The fluid-structure interaction response is simulated using an immersed boundary approach coupled with a finite volume solver for incompressible, viscous flow. The effects of large beam deformation, membrane tension, and coupled electromechanical responses are all considered. Validation studies are shown for the motion of a flexible filament in uniform flow, and for a piezoelectric beam subject to base vibration. The predicted flutter velocities and frequencies also compared well with published experimental and numerical data over a range of Reynolds numbers for varying fluid and solid combinations. The results showed that for a heavy beam in a light fluid (i.e., high βρ regime), flutter incepts at a lower critical speed with a lower reduced frequency than for a light beam in a heavy fluid (i.e., low βρ regime). In the high βρ regime, flutter develops at the second mode and is only realized when the fluid inertial forces are in balance with the solid elastic restoring forces, which leads to large amplitude oscillations and complex wake patterns; the flutter speed is practically independent of the Reynolds number (Re) and solid to fluid mass ratio (βρ), because the response is dominated by the solid inertial forces. In the low βρ regime, fluid inertial forces dominate, flutter develops at higher modes and is only realized when the solid inertial forces are proportioned to the solid elastic restoring forces; the flutter speed depends on both Re and βρ, and viscous force and beam tension effects tend to delay flutter and reduce vibration amplitudes, leading to thinner, more simplified wake patterns. The results demonstrate that energy extraction via fluttering piezoelectric beams is possible. The overall efficiency was observed to be influenced by the piezoelectric circuit resistance, which is known to be directly related to the square of the piezoelectric coupling factor. The results show that the maximum strain limit of piezoelectrics may be exceeded, and hence careful optimization of the material and geometry is recommended to maximize the energy capture for a given range of expected flow conditions while satisfying safety and reliability requirements.

Sound random incidence absorption characteristics of a thin plate with PZT shunted with passive electrical circuits

Sound absorption of a thin plate with PZT shunted with passive electrical circuits in diffuse field Sound absorbing properties of a plate with piezoelectric shunted circuit in diffuse field is investigated in this paper. A theoretical model of a thin plate with piezoelectric patch and electrical circuit under random sound incidence is proposed and numerically analyzed. Measurement is also carried out in a reverberation room and found to be in good agreements with the theoretical model. Theoretical and measured results confirmed that this technology has a potential to improve sound absorption at low frequency

A Flush-Mounted Resonant Ice Detection Sensor with High Sensitivity

An ice detection system consisting of a resonant piezoelectric sensing-element and closed-loop circuit has been developed to automatically and distinctly sense ice films up to 1.3 mm thick. Accretion of ice and/or water on the sensor surface modifies the effective mass and/or stiffness of the vibrating transducer; these variations are sensed by measuring the changes in transducer resonant frequency. In case of ice films, resonant frequency of the transducer increases steadily from 60.9 kHz with no ice to 131.5 kHz when the ice film is 1.3mm thick. The time and temperature stability experiments revealed frequency variety no more than 1 kHz. The resolution of this sensor is better than 0.06mm.

Implementing a Piezoelectric Transformer for a Ferroelectric Phase Shifter Circuit

This paper describes the successful development of a piezoelectric transformer-based driver circuit used to bias a ferroelectric phase shifter. The proof-of-concept circuit achieves voltages in excess of 400 VDC and accomplishes 0 to 180 degrees of phase shift at Ka-band. The ferroelectric phase shifter is the fundamental component in a new type of scanning phased array, the ferroelectric reflectarray. The coplanar ferroelectric phase shifter requires only one control signal, currently generated by magnetic circuit components. However magnetic devices suffer from resistive and magnetic losses, and dimensional and economic costs. New phased array architecture, not reliant on magnetics, can be realized because the piezoelectric transformer allows a low level signal to be routed to each phase shifter and converted to the proper bias voltage levels at each phase shifter. This research explores the use of a piezoelectric transformer (PT) as the alternative enabling component in the voltage supply for a ferroelectric phase shifter utilizing piezoelectrics in an AC-DC converter.

Implementation of a Single Supply Pre-biasing Circuit for Piezoelectric Energy Harvesters

Abstract Increased output power can be obtained from piezoelectric energy harvesters by using switching circuits that modify the charge on the material at the extremes of cantilever travel. Here we present an implementation of the most efficient of these charge modification techniques, single-supply piezoelectric pre-biasing. We describe practical results from this scheme and circuit details, including power processing components and control circuits. The power circuit current paths are synchronously commutated with MOSFETs, removing inefficient diode voltage drops. The control circuit is implemented using low power discretes. A useful output power of 2.6 mW was achieved after a 400 μW reduction required for the control circuitry. This is a factor of 4.3 greater than when the harvester was connected to a passive diode bridge and is greater than can be achieved by other piezoelectric interface circuits using an inductor with the same Q-factor.

Structural multi-modal damping by optimizing shunted piezoelectric transducers

The capacity of different auto-supplied devices using shunted piezoelectric circuits are studied here to improve structural damping by avoiding implementation of complex and heavy control devices. The presented technique uses a dedicated numerical piezo-mechanical model combining both mechanical and electrical coupling parameters. An original methodology are also introduced for optimizing the parameters of electrical shunt circuits connected to piezoelectric elements and also structural locations of these integrated transducers. The results, experimentally validated (on beams and a plate), demonstrate that vibrations can be significantly reduced when shunted piezoelectric devices are mounted on a real structure. Finally, the proposed methodology is used for optimizing shape and location of the shunted piezoelectric patches to damp several modes of a plate.

Quantization of Mesoscopic Quartz Piezoelectric Crystal Equivalent Circuit

By using the advanced quantum theory of mesoscopic circuits, a mesoscopic quartz piezoelectric crystal equivalent circuit is quantized. The energy spectrum and wave functions of the system are obtained with perturbative method and the current quantum fluctuation are calculated as an application. The detail characters of energy spectrum and wave functions in the system would be helpful to the design of integrate circuit.

Harvesting Ambient Kinetic Energy With Switched-Inductor Converters

The potential application space for miniaturized systems like wireless microsensors is expansive, from reconnaissance mission work and remote sensors to biomedical implants and disposable consumer products. Conforming to microscale dimensions, however, constrains energy and power to such an extent that sustaining critical power-hungry functions like wireless communication is problematical. Harvesting ambient kinetic energy offers an appealing alternative, except the act of transferring energy requires power that could easily exceed what the harvester generates in the first place. This paper reviews piezoelectric and electrostatic harvester circuits, describes how to design low-power switched-inductor converters capable of producing net energy gains when supplied from piezoelectric and electrostatic transducers, and presents experimental results from prototype embodiments. In the electrostatic case shown, the controller dissipated 0.91 nJ per cycle and the switched-inductor precharger achieved 90.3% efficiency to allow the harvester to net a gain of 2.47 nJ per cycle from a capacitor that oscillated between 157 and 991 pF. The piezoelectric counterpart harnessed 1.6 to 29.6 μW from weak periodic vibrations with 0.05-0.16- m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> accelerations and 65.3 μJ from (impact-produced) nonperiodic motion.

QUANTIZATION OF MESOSCOPIC QUARTZ PIEZOELECTRIC CRYSTAL EQUIVALENT CIRCUIT

In the framework of an advanced quantum theory for mesoscopic electric circuits in accord with the discreteness of electric charges, a mesoscopic quartz piezoelectric crystal equivalent circuit is quantized. To resolve the finite difference Schrödinger equation, an improved parameter perturbative method is proposed when WKB and perturbative method are inapplicable. With this method, the energy spectrum and wavefunctions of the system are obtained and used to calculate current quantum fluctuation as an application. The new method would be helpful to the application of the mesoscopic circuits quantum theory. Besides, the detail characters of energy spectrum and wavefunctions in the system would be helpful to the design of integrate circuit.

Structural multi-modal damping by optimizing shunted piezoelectric transducers

The capacity of different auto-supplied devices using shunted piezoelectric circuits are studied here to improve structural damping by avoiding implementation of complex and heavy control devices. The presented technique uses a dedicated numerical piezo-mechanical model combining both mechanical and electrical coupling parameters. An original methodology are also introduced for optimizing the parameters of electrical shunt circuits connected to piezoelectric elements and also structural locations of these integrated transducers. The results, experimentally validated (on beams and a plate), demonstrate that vibrations can be significantly reduced when shunted piezoelectric devices are mounted on a real structure. Finally, the proposed methodology is used for optimizing shape and location of the shunted piezoelectric patches to damp several modes of a plate.

An electromechanical low frequency panel sound absorber

The sound absorbing properties of a thin micro-perforated plate (MPP) coated with piezoelectric material with shunt damping technology is investigated. First a theoretical model is presented to predict the sound absorption coefficients of a thin plate attached with a piezoelectric patch and electrical circuits. Then the model is extended to analyze the sound absorption for a thin plate with micro perforations and piezoelectric material. Measurements are also carried out in an impedance tube and found to be in good agreements with the theoretical model. The sound absorption of the constructions can be much improved by tuning the electrical circuits.

Finite Element Based Design of Piezoelectric Vibration Damper

Vibration control using combination of piezoelectric material and electrical circuits can remove the vibration energy from the host structure. The need for passive damping techniques arises to avoid the complexities and energy requirements associated with other vibration control techniques. Passive damping technique for reduction of vibration of structures by introduction of shunted piezoelectric patch is presented in this study. Finite element analysis is performed for a cantilever beam with shunted piezoelectric patch on it. The prediction of the model is validated against experimental published results. The obtained results demonstrate the feasibility of using piezoelectric patches with passive shunting as effective means for damping out the vibrations. The aim of this research work is the advancement of the coupled field analysis for structural vibration control with advanced methodology and to promote the design and analysis activities in the field of passive vibration control techniques using smart structures. Results obtained showed up to 86% reduction in the amplitude of the host structure which shows good agreement with published experimental results.

Development of Mathematical Model of a Mechatronic System

This paper is a continuation of earlier publications of the authors related to the analysis of mechatronic systems including piezoelectric materials used as sensors or actuators for stabilization and damping of mechanical vibration. It was demonstrated that only very accurate mathematical model of the system with the piezoelectric transducers and external electric circuit attached to a mechanical system like a beam or a shaft by a glue layer allows the engineers to design the system with required dynamic parameters. Geometrical and material parameters of all the components have to be taken into account because neglecting the influence of one of them results in erroneous analysis results [1-4]. The paper presents the improved mathematical model of the considered mechatronic system. The assumption of pure shear of the connection layer is rejected during modeling and deformation of the layer is taken into consideration. The purpose of the reported enhancement of the mathematical model of the considered mechatronic system is to improve accuracy of computational results.

Vibration Suppression of a Quadrilateral Plate Using Hybrid Piezoelectric Circuits

A practical method for suppressing random vibrations of a quadrilateral plate using the active/ passive hybrid piezoelectric circuits is developed. Firstly, the finite element model of the plate bonded with piezoelectric actuators is established by using the commercial software packages ANSYS®. Afterwards, matrices in these electromechanically coupled equations are directly imported into MATLAB® platform for later use. Time histories of the random excitations are obtained from the output of a band-pass FIR filter driven by white noise. Hybrid piezoelectric shunt circuits that combine the passive circuits with active voltage sources are used to suppress random vibrations of plate under the designed loads. Simulation results demonstrate that with appropriate circuit parameters, the hybrid control is more effective than passive or purely active control.

3C11 Control of Structural Sound Radiation and Vibration Using Shunt Piezoelectric Materials

In this paper, structural sound and vibration control using passive and semi-active shunt piezoelectric damping circuits is presented. A piezoelectric patch with an electrical shunt circuit is bonded to a base structure. When the structure vibrates, the piezoelectric patch strains and transforms the mechanical energy of the structure into electrical energy, which can be effectively dissipated by the shunt circuit. Hence, the shunt circuit acts as a means of extracting mechanical energy from the base structure. Different types of shunt circuits (such as an RL series circuit, an RL parallel circuit and an RL-C circuit) employed in the passive damping arrangement, are analyzed and compared. Using the impedance method, the general modelling of different shunt piezoelectric damping techniques is presented. The piezoelectric shunt circuit can be seen as an additional frequency-dependence damping of the system. One of the primary concerns in shunt damping is to choose the optimal parameters for shunt circuits. In past efforts most of the proposed tuning methods were based on modal properties of the structure. These methods are used to minimize the response of a particular structural mode whilst neglecting the contribution of the other modes. In this study, a design method based on minimization of the sound power of the structure is proposed. The optimal parameters for shunt circuits are obtained using linear quadratic optimal control theory. Numerical simulations are performed for each of these shunts techniques focusing on minimizing radiated sound power from a clamped plate. It is found that the RL series, RL parallel and pulse-switching circuits have basically the same control performance. The RL-C parallel circuit allows us to reduce the value of the inductance L due to the insertion of an external capacitance C. However, the control performance will be reduced simultaneously. The pulse-switching circuit is more stable than an RL series circuit with regard to structural stiffness variations. Finally, experimental results are presented using an RL series/parallel shunt circuit, RL-C parallel shunt circuit and pulse-switching circuit. The experimental results have shown that the vibration and noise radiation of a structure can be reduced significantly by using shunt circuits. The theoretical and experimental techniques presented in this study provide a valuable tool for effective shunt piezoelectric damping applied for control of vibration damping and radiated sound.

Influences of different types of piezoelectric shunting circuits on band gaps of phononic beam

Piezoelectric patches connected with shunting circuits are periodically placed along a base beam, forming a one-dimensional phononic crystal. Different types of shunting circuits will determine the band structure of the beam. Resistive shunting circuits can restrain the beam’s modal vibrations to some extent and the band gaps of the beam can be changed by weakening the piezoelectric effect. LC shunting circuits can produce locally resonant gaps induced by LC circuits’ electromagnetic oscillations excited by piezoelectric patches. When resistors are added to the LC circuits, the LC circuits’ oscillation will be weakened and the attenuation amplitude in the band gaps will be lowered, but the scope of band gaps are widened.

Outer hair cell electromechanical properties in a nonlinear piezoelectric model

A nonlinear piezoelectric circuit is proposed to model electromechanical properties of the outer hair cell (OHC) in mammalian cochleae. The circuit model predicts (a) that the nonlinear capacitance decreases as the stiffness of the load increases, and (b) that the axial compliance of the cell reaches a maximum at the same membrane potential for peak capacitance. The model was also designed to be integrated into macro-mechanical models to simulate cochlear wave propagation. Analytic expressions of the cochlear-partition shunt admittance and the wave propagation function are derived in terms of OHC electro-mechanical parameters. Small-signal analyses indicate that, to achieve cochlear amplification, (1) nonlinear capacitance must be sufficiently high and (2) the OHC receptor current must be sensitive to the velocity of the reticular lamina.

Adaptive Piezoelectric Vibration Control With Synchronized Switching

An autonomous vibration controller that adapts to variations in a system’s mass, stiffness, and excitation, and that maximizes dissipation through synchronized switching is described. In the model and laboratory measurements, a cantilever beam is driven through base excitation and two piezoelectric elements are attached to the beam for vibration control purposes. The distributed-parameter model for the beam-element system is discretized by using Galerkin’s method, and time histories of the system’s response describe the controller’s attenuation characteristics. The system is piecewise linear, and a state-to-state modal analysis method is developed to simulate the coupled dynamics of the beam and piezoelectric circuit by mapping the generalized coordinates between the sets of modes for the open-switch and closed-switch configurations. In synchronized switching control, the elements are periodically switched to an external resonant shunt, and the instants of optimal switching are identified through a filtered velocity signal. The controller adaptively aligns the center frequency of a bandpass filter to the beam’s fundamental frequency through a fuzzy logic algorithm in order to maximize attenuation even with minimal a priori knowledge of the excitation or the system’s mass and stiffness parameters. In implementation, the controller is compact owing to its low inductance and computational requirement. The adaptive controller attenuates vibration over a range of excitation frequencies and is robust to variations in system parameters, thus outperforming traditional synchronized switching.

Reduction of Structural Sound Radiation and Vibration Using Shunt Piezoelectric Materials

In this paper, structural sound and vibration control using passive and semi-active shunt piezoelectric damping circuits is presented. A piezoelectric patch with an electrical shunt circuit is bonded to a base structure. When the structure vibrates, the piezoelectric patch strains and transforms the mechanical energy of the structure into electrical energy, which can be effectively dissipated by the shunt circuit. Hence, the shunt circuit acts as a means of extracting mechanical energy from the base structure. First, different types of shunt circuits (such as RL series circuit, RL parallel circuit and RL-C circuit), employed in the passive damping arrangement, are analyzed and compared. By using the impedance method, the general modelling of different shunt piezoelectric damping techniques is presented. The piezoelectric shunt circuit can be seen as additional frequency-dependence damping of the system. One of the primary concerns in shunt damping is to choose the optimal parameters for shunt circuits. In past efforts most of the proposed tuning methods were based on modal properties of the structure. These methods are used to minimize the response of a particular structural mode whilst neglecting the contribution of the other modes. In this study, a design method based on minimization of the sound power of the structure is proposed. The optimal parameters for shunt circuits are obtained using linear quadratic optimal control theory. In general, the passive shunt circuit techniques are an effective method of modal damping. However, the main drawback of the passive shunt circuit is that the shunt piezoelectric is very sensitive to tuning errors and variations in the excitation frequency. To overcome this problem, the pulse-switching shunt circuit, a semi-active continuous switching technique in which a RL shunt circuit is periodically connected to a bonded piezoelectric patch, is introduced as structural damping. The switch law for pulse-switching circuit is discussed based on the energy dissipation technique. Compared with a standard passive piezoelectric shunt circuit, the advantages of the pulse-switching shunt circuit is a small required shunt inductance, a lower sensitivity to environmental changes and easier tuning. Very low external power for the switch controller is required so it may be possible to extract this energy directly from the vibration of the structure itself. Numerical simulations are performed for each of these shunts techniques focusing on minimizing radiated sound power from a clamped plate. It is found that the RL series, RL parallel and pulse-switching circuits have basically the same control performance. The RL–C parallel circuit allows us to reduce the value of the inductance L due to the insertion of an external capacity C. However, the control performance will be reduced simultaneously. The pulse-switching circuit is more stable than RL series circuit with regard to structural stiffness variations. Finally, experimental results are presented using an RL series/parallel shunt circuit, RL-C parallel shunt circuit and pulse-switching circuit. The experimental results have shown that the vibration and noise radiation of a structure can be reduced significantly by using these shunt circuits. The theoretical and experimental techniques presented in this study provide a valuable tool for effective shunt piezoelectric damping.