Series Resonant Frequency Research Articles

Analysis of uncertainty in measurement of electron temperature in low-pressure inductively coupled plasmas using microwave cutoff probe

Abstract In this study, we performed electron temperature measurements by using a square cutoff probe. Further, the measurement uncertainty was comprehensively analysed. The square cutoff probe allows for the measurement of the electron temperature based on the measured electron series resonance frequency and that of the electron plasma frequency based on the transmission spectrum of the plasma. The electron temperatures were determined under varying gas pressures and input power conditions, and the results were compared with those obtained using a single Langmuir probe. Also, the impact of electron-neutral collision frequency on electron temperature measurement using square cutoff probe was analyzed based on a plasma equivalent circuit model. The square cutoff probe is expected to serve as a valuable diagnostic tool for the precise characterisation of electron temperature, offering localised, accurate, and easily interpretable features.

РОЗРАХУНОК РЕГУЛЮВАЛЬНИХ ХАРАКТЕРИСТИК РЕЗОНАНСНИХ ПЕРЕТВОРЮВАЧІВ МЕТОДОМ СУПЕРПОЗИЦІЇ

The work presents the calculations of the control characteristics of the full-bridge resonant converter with a series resonant LLC circuit and frequency control by two methods - the first harmonic method and the superposition method. The theoretical results were verified by the analytical-structural modeling method. The power circuit of the resonant converter for the analysis of electromagnetic processes is replaced by a linear T-shaped circuit with two series resonant RLC-circuits and equivalent generators of rectangular voltages, which simulate a transistor inverter and a diode rectifier in the quasi-continuous current mode. Analytical-structural modeling method consists in partly analytical and partly structural ways of building a numerical model of the resonant converter in the form of the simulation model in the MATLAB-Simulink environment. Linear structural links of the model are created on the basis of integral equations of circles. Non-linear links are created based on the non-linear functions and causal relationships. The structural model based on these links takes into account the nonlinearity of the elements of the power circuit of the resonant converter and is based on simpler mathematical expressions compared to the equivalent mathematical model of the resonant converter. The structural model corresponds to the idea of the resonant converter in the form of the resonant circuit with independent equivalent voltage generators and allows to adjust the magnetic coupling coefficient between the transformer windings and simulate processes with arbitrary control functions of equivalent generators. The peculiarity of the use of the superposition method for calculating the static characteristics of the resonant converter is the need to match the voltage phases of the equivalent generators of the equivalent circuit during the changes of the operating frequency or relative load voltage. The dependence of the input voltage of the rectifier, which is simulated by the second equivalent generator, on the processes of the power circuit of the real resonant converter, determines the conditions for matching (adjusting) the phases of the equivalent generators. References 30, figures 5.

Adjustable effective electromechanical coupling of Lamb wave resonator using AlN/Sc0.096Al0.904N composite films

With the rapid development of fifth-generation communication technology, there are more and more 5 G frequency bands and their bandwidths differ. Therefore, many researchers devote themselves to the study of resonators with adjustable electromechanical coupling coefficient. In this paper, we apply composite films to the Lamb wave resonator with a double-IDT configuration to achieve adjustable effective electromechanical coupling coefficient (Keff 2) of the first symmetric mode. The experimental results show that with the increase of the thickness ratio, the series resonant frequency ( fs ) of the resonator decreases from 2.567 GHz to 2.333 GHz; and the parallel resonant frequency ( fp ) of the resonator decreases from 2.608 GHz to 2.396 GHz. The Keff 2 is adjusted from 3.82% to 6.32% and the Δf ( fp−fs ) is adjusted from 41 to 63 MHz by using the AlN/Sc0.096Al0.904N composite films with different thickness ratios. This method may be an efficient way to adjust the bandwidth of the filter to meet the needs of different frequency bands.

Impedance Circle Modeling and Dynamic Characteristics Analysis of Contactless Energy Transfer System Under Load Variations in Rotary Ultrasonic Machining

In rotary ultrasonic machining, contactless energy transfer (CET) is developed to transmit energy to the transducer at the series resonant frequency or resonant frequency of the transducer. Specifically, during energy transmission, variations in working conditions such as variable axial forces will change the load of the transducer and introduce undesired dynamic effects into the contactless energy transfer system (CETS). In order to explore the connections between these variations and the working performance more directly and theoretically, a new theoretical model—CETS impedance circle is proposed in this paper to reflect the CETS dynamic characteristics, including the CETS frequency characteristics and the relationships between CETS transfer performances at different frequencies under load variations. With the developed theoretical model, the effect of load variations on the trends of CETS impedance circle is investigated. Moreover, based on the impedance circle and its trends, the CETS frequency characteristics, the effect of primary series compensation, and a comparison of the transfer performances at the two working frequencies are theoretically studied. Finally, the CETS impedance circle theories are experimentally verified, and the experimental results are consistent with the analysis of the theoretical model.

Impacts of Electrode Resistance on Resonance Characteristics of Film Bulk Acoustic Resonators

In the actual manufacturing process of film bulk acoustic resonators (FBAR), metal leads are necessary to complete the electrical topological connection. However, the electrode resistance will significantly influence the characteristics of the resonator. In this paper, the influence of electrode resistance on resonance characteristics of FBAR is analyzed. To be specific, how different electrode resistances affect the quality factor, impedance value, and electromechanical coupling factor of the FBAR series-parallel resonance frequencies is studied by incorporating the electrode resistances into an overall equivalent electromechanical model (i.e., the Mason model) and the COMSOL finite element simulation method. The results show that the increase of electrode resistance will result in the decrease of the series resonant frequency, the impedance value increases significantly and the quality factor decreases significantly at series resonant, while the parallel resonant frequency does not change, the impedance value slightly increases and the quality factor slightly decreases at parallel resonant, and their electromechanical coupling factor slightly increases.

Design, Fabrication and Performance Analysis of a Portable, Antenna Analyzer Based, Quartz Crystal Microbalance Measuring System with Energy Dissipation

Impedance measurements play a critical role in analyzing the electrical behavior of piezoelectric biosensors in general. Antenna analyzers are engineered to measure the specific case of input impedance for antenna systems. In this study small form factor antenna analyzer is repurposed to work as driving circuit for a Quartz Crystal Microbalance (QCM) biosensor in combination with a single board computer as an indication of how small and portable an impedance measuring system can be made, while allowing monitoring of important parameters of series and parallel resonance frequencies together with dissipation factor. A QCM crystal with a 10 MHz fundamental resonance frequency is employed to determine the limit of detection of the system in Bovine Serum Albumin (BSA) and glycerol solutions. Dissipation factor and phase angle were monitored during the experiments. Limit of detection is 20 µg/ml BSA in phosphate buffer saline (PBS) and 250 µl of glycerol in 100 ml of deionized water.

Influence of the Gain–Bandwidth of the Front-End Amplifier on the Performance of a QEPAS Sensor

The quartz tuning fork used as an acoustic sensor in quartz-enhanced photo-acoustic spectroscopy gas detection systems is usually read out by means of a transimpedance preamplifier based on a low-noise operational amplifier closed in a feedback loop. The gain–bandwidth product of the operational amplifier used in the circuit is a key parameter which must be properly chosen to guarantee that the circuit works as expected. Here, we demonstrate that if the value of this parameter is not sufficiently large, the response of the preamplifier exhibits a peak at a frequency which does not coincide with the series resonant frequency of the quartz tuning fork. If this peak frequency is selected for modulating the laser bias current and is also used as the reference frequency of the lock-in amplifier, a penalty results in terms of signal-to-noise ratio at the output of the QEPAS sensor. This worsens the performance of the gas sensing system in terms of ultimate detection limits. We show that this happens when the front-end preamplifier of the quartz tuning fork is based on some amplifier models that are typically used for such application, both when the integration time of the lock-in amplifier filter is long, to boost noise rejection, and when it is short, in order to comply with a relevant measurement rate.

Low-Capacitance CHB-Based SST Based on Resonant Push–Pull Decoupling Channel

Cascaded H-bridge based solid state transformer (CHB-SST) has been the typical scheme in medium and low voltage AC/DC conversion applications, and large-size capacitance caused by 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> -order ripple of submodules (SMs) is the inherent problem of CHB-based systems. This paper proposes a novel low-capacitance CHB-SST (ZCHB-SST) based on zero-impedance resonant push-pull (ZRPP) decoupling channel for ripple power. ZRPP presents zero-impedance characteristic at its switching frequency equaling to series resonant frequency, which makes the equivalent parallel of CHB AC-link capacitors, and provides a decoupling channel for ripple-power. Therefore, the horizontal SMs ripple-power can achieve mutual cancellation based on their own three-phase symmetry, which significantly reduces the size of AC-link capacitance. In addition, the elimination of SMs ripple-voltage achieves the elimination of grid zero-sequence harmonics from root cause, and the mutual clamping of parallel AC-link capacitors also achieves the voltages self-balancing, which reduces the complex of system control. The CHB-SST configuration, operating principle, ripple-power decoupling, SMs voltage self-balancing, system design, and evaluation are discussed in this paper. Finally, the effectiveness of the proposed CHB-SST is verified by simulation and experiment.

Parameters identification of an ultrasonic transducer based on right-semicircle fitting of admittance circle

We propose an accurate parameter identification method for Butterworth-Van Dyke (BVD) model via Fast Identification of BVD model based on Right-semicircle Fitting of Admittance (FIRFA), which is composed of the fast search algorithm for series resonant frequency (FSSRF) and the identification of BVD model based on Right-semicircle Fitting of Admittance (IRFA). In order to verify the algorithm, we establish an Ultrasonic Transducer Identification System (UTIS) to measure the BVD model of the 62 kHz and the 140 kHz ultrasonic transducer. The accuracy and the time consumption of the FSSRF algorithm are investigated. Besides, the nonlinear phenomenons of the BVD model parameters varying with the driving voltage are qualitatively analyzed. The results show that R1 and L1 will increase, C1 will decrease when the driving voltage increases.

Design and Characterization of Ultrasonic Langevin Transducer 20 kHz Using a Stepped Horn Front-Mass

Ultrasonication is a method that is widely used in various fields. One of its applications is to accelerate the process of homogenization, emulsification, and extraction. In the ultrasonicator system, the transducer is an extremely important device. The resonant frequency, longitudinal vibration amplitude, and electromechanical coupling are the targets in designing an ultrasonic transducer. In this investigation, the main contribution was the development of a simple and effective method for mechanically tuning the resonant frequency of the transducer by adding mass to the front end of the mass or stepped horn. This study also aimed to obtain optimal results by examining the effects of geometric dimensions, bolt prestress, stress distribution, resonant frequency, amplitude, and electrical impedance. The ultrasonic transducer model was designed with a resonant frequency of 20 kHz and simulated using the finite element analysis. The steps involved included calculating the dimensions and geometric structure of the transducer, modeling using the finite-element method, and experimental validation. The simulation results and measurements showed that the series resonant frequency, electrical impedance, and effective electromechanical coupling of the Model-4 transducer 16∙13 mm radiator configuration were 20.15 kHz, 100 Ω, and 0.2229 from the simulation results, and 20.17 kHz, 24.91 Ω, and 0.2033 from the measurement results. A percentage difference, or relative error, of 0.1% was obtained between the simulation and the experimental results for this Model-4 with bolt prestressing at 15 kN.

A Turn-Ratio-Changing Half-Bridge CLLC DC–DC Bidirectional Battery Charger Using a GaN HEMT

This paper presents a 250 kHz bidirectional battery charger circuit using a GaN HEMT. The charger is subjected to a high-/low-side constant voltage at 200 V/20 V. The charger circuit is a hybrid of the LLC and flyback circuit topologies. Both the power output analysis and efficiency control of this circuit are simplified when the magnetization current is minimized using the low-resistance GaN HEMT. The switching frequency is controlled to match the series resonance in a way that is analogous to conventional LLC circuit controls, while the duty ratio that determines the power output and the dead time, which determines the zero voltage switching, is controlled in an analogous manner to the flyback circuit control. The charging and discharging modes were altered by applying a double-throw relay that changes the transformer turn ratio, which is different from conventional LLC designs using the switching frequency adjustment. A nominal turn ratio with Np = 35 and Ns = 3.5 for a 200 V/20 V converter can only produce an internal series resonance with no current flowing in any charging direction. The proposed circuit using a transformer with multiple windings (Np = 35, Ns,F = 4, and Ns,R = 3) was fabricated to deliver 125 W output power from the power grid battery to the vehicle battery in the forward (charging) mode and 90 W in the reverse (discharging) mode. The conversion efficiency was calculated to be as high as 97% in the forward mode and 95% in the reverse mode. The high conversion efficiency is due to the characteristics of the GaN HEMT, including low resistive and switching losses. The equations derived in this paper associate these losses with the series resonant frequency and power conversion rate, which highlight the advantages of using a GaN HEMT in this CLLC design.

Investigation on anchor and base design for aluminum nitride flexural mode resonators

This paper investigates the impact of base and anchor on the quality factor (Q) of piezoelectric microelectromechanical system (MEMS) tuning fork resonators vibrating in in-plane flexural mode, and proposes a new strategy to improve Q significantly. Finite element method simulation and measured results reveal that base and anchor geometries have a significant impact on the thermoelastic damping (TED) which dominates the overall resonator quality factor. For the first time, we accurately extract Q value related to TED of piezoelectric tuning fork resonators by cryogenic temperature experiment, which is consistent with FEM simulation results. According to the analysis, a wider anchor or a longer base should promote overall Q by restraining the thermal conduction induced by TED. On the other hand, increase of width or length of anchor will force the out-of-plane flexural modes closer to the target mode, reducing the overall Q by multimode effect. With a wide anchor and a pillar structure under the base to suppress multimode effect, the resonator Q could be improved by 65% to more than 11 000 and impedance at series resonant frequency (f s) could be reduced by 78% to 6.5 kΩ. To our knowledge, the proposed resonator exhibits the highest f× Q and lowest motional impedance among the reported in-plane mode piezoelectric MEMS tuning fork resonators.

Electrode design for multimode suppression of aluminum nitride tuning fork resonators

This paper is focused on electrode design for piezoelectric tuning fork resonators. The relationship between the performance and electrode pattern of aluminum nitride piezoelectric tuning fork resonators vibrating in the in-plane flexural mode is investigated based on a set of resonators with different electrode lengths, widths, and ratios. Experimental and simulation results show that the electrode design impacts greatly the multimode effect induced from torsional modes but has little influence on other loss mechanisms. Optimizing the electrode design suppresses the torsional mode successfully, thereby increasing the ratio of impedance at parallel and series resonant frequencies (Rp/Rs) by more than 80% and achieving a quality factor (Q) of 7753, an effective electromechanical coupling coefficient (kteff2) of 0.066%, and an impedance at series resonant frequency (Rm) of 23.6 kΩ. The proposed approach shows great potential for high-performance piezoelectric resonators, which are likely to be fundamental building blocks for sensors with high sensitivity and low noise and power consumption.

A Driving Power Supply for Piezoelectric Transducers Based on an Improved LC Matching Network

In the ultrasonic welding system, the ultrasonic power supply drives the piezoelectric transducer to work in the resonant state to realize the conversion of electrical energy into mechanical energy. In order to obtain stable ultrasonic energy and ensure welding quality, this paper designs a driving power supply based on an improved LC matching network with two functions, frequency tracking and power regulation. First, in order to analyze the dynamic branch of the piezoelectric transducer, we propose an improved LC matching network, in which three voltage RMS values are used to analyze the dynamic branch and discriminate the series resonant frequency. Further, the driving power system is designed using the three RMS voltage values as feedback. A fuzzy control method is used for frequency tracking. The double closed-loop control method of the power outer loop and the current inner loop is used for power regulation. Through MATLAB software simulation and experimental testing, it is verified that the power supply can effectively track the series resonant frequency and control the power while being continuously adjustable. This study has promising applications in ultrasonic welding technology with complex loads.

An equivalent circuit for magnetoelectric composites operating in a longitudinal mode resonance: BAW-actuated mechanical antenna

It brings new design perspectives to study mechanical antenna in the view of circuit rather than the electromagnetic field. In this paper, an equivalent circuit of bulk acoustic wave (BAW) antenna is constructed by using constitutive relation of magnetoelectric composites and Newton’s governing equation. Based on this circuit, series and parallel resonant frequencies of two phases for BAW antenna are simulated in advanced design system (ADS) and magnetoelectric coupling coefficient is calculated. The results show that the electromechanical coupling coefficient is about 6%, the magnetomechanical coupling coefficient is about 86%, and the magnetoelectric coupling coefficient is about 5.2% under the existing material system (AlN and FeGaB). The magnetoelectric voltage gain is derived based on Kirchhoff’s Current Law, which contributes to studying the influence of the two phases thickness ratio on the performance of BAW antenna. The results show that BAW antenna has the optimal energy coupling and conversion when the thickness ratio of the two phases is 1:1. The input and the output impedances of BAW antenna are calculated by T-parameter matrix, which are perfectly matched with the results in ADS simulation. Relevant experiments have been carried out by preparing the magnetoelectric antenna based on PZT and Terfenol-D materials to verify the universality of the model.

Signal-to-Noise Ratio Analysis for the Voltage-Mode Read-Out of Quartz Tuning Forks in QEPAS Applications

Quartz tuning forks (QTFs) are employed as sensitive elements for gas sensing applications implementing quartz-enhanced photoacoustic spectroscopy. Therefore, proper design of the QTF read-out electronics is required to optimize the signal-to-noise ratio (SNR), and in turn, the minimum detection limit of the gas concentration. In this work, we present a theoretical study of the SNR trend in a voltage-mode read-out of QTFs, mainly focusing on the effects of (i) the noise contributions of both the QTF-equivalent resistor and the input bias resistor RL of the preamplifier, (ii) the operating frequency, and (iii) the bandwidth (BW) of the lock-in amplifier low-pass filter. A MATLAB model for the main noise contributions was retrieved and then validated by means of SPICE simulations. When the bandwidth of the lock-in filter is sufficiently narrow (BW = 0.5 Hz), the SNR values do not strongly depend on both the operating frequency and RL values. On the other hand, when a wider low-pass filter bandwidth is employed (BW = 5 Hz), a sharp SNR peak close to the QTF parallel-resonant frequency is found for large values of RL (RL > 2 MΩ), whereas for small values of RL (RL < 2 MΩ), the SNR exhibits a peak around the QTF series-resonant frequency.

Dynamic Compensation Optimization and Frequency Characteristic Analysis for Contactless Energy Transfer Under Load Variations in Rotary Ultrasonic Machining

In rotary ultrasonic machining, contactless energy transfer (CET) converts power from an ultrasonic power supply to the ultrasonic transducers. Two-side compensation circuits improve the efficiency of this process, but the addition of secondary compensation causes problems such as dynamic imbalance. Load changes affect the performance of CET system (CETS) with compensation, and dynamic compensation is needed for good CETS performance, such as high transfer efficiency and output power. This article investigates the frequency characteristics of CETS without compensation under different loads. The effects of two-side compensation on CETS under load variations is studied for the dynamic compensation characteristic. The comparison of mathematical model and performance of CETS with dynamic compensation are investigated to propose the optimized dynamic compensation. The model of CETS with optimized dynamic compensation under load variations is developed. The CETS frequency characteristics with optimized dynamic compensation are studied. The experimental results basically agree with the calculated results. The CETS with optimized dynamic compensation at the series resonant frequency can produce high transfer efficiency, high output power, low input impedance range under load variations in the cutting process of RUM, and solves the problems caused by the secondary side compensation.

Pulse Frequency Modulated Interleaved Boost-Integrated LC Series Resonant Converter With Frequency-Free Designed Transformer

In this article, we propose a novel interleaved boost-integrated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> series resonant converter, in which the series resonant tank is located on the secondary side. Moreover, the input and output of the interleaved boost unit are in series directly, which is helpful to reduce the voltage stress of the output filter capacitor of boost unit. With the proposed pulse frequency modulation, except for that the output voltage can be controlled as constant under different input voltages, another feature is that the high-frequency transformer design is related to the series resonant frequency instead of the switching frequency. Hence, the proposed converter can operate under a very wide switching frequency range with a constant maximum magnetic flux density. The zero voltage switching and zero current switching can be achieved for all switches diodes. Finally, a 500-W prototype with a switching frequency range from 60 to 200 kHz is built to verify the operation principles of the proposed converter and modulation.

Exploring electromechanical utility of GaAs interdigitated transducers; using finite-element-method-based parametric analysis and experimental comparison

Analysis of interdigitated transducers often relies on phenomenological models to approximate device electrical performance. While these approaches prove essential for signal processing applications, phenomenological models provide limited information on the device’s mechanical response and physical characteristics of the generated acoustic field. Finite element method modeling, in comparison, offers a robust platform to study the effects of the full device geometry on critical performance parameters of interdigitated transducer devices. In this study, we fabricate a surface acoustic wave resonator on semi-insulating GaAs (100), which consists of an interdigitated transducer and acoustic mirror assembly. The device is subsequently modeled using fem software. A vector network analyzer is used to measure the experimental device scattering response, which compares well with the simulated results. The wave characteristics of the experimental device are measured by contact-mode atomic force microscopy, which validates the simulation’s mechanical response predictions. We further show that a computational parametric analysis can be used to optimize device designs for series resonance frequency, effective coupling coefficient, quality factor, and maximum acoustic surface displacement.

A phase‐shift modulated series resonant converter achieving zero‐voltage and zero‐current switching for wide output voltage range battery charging applications

In this article, a phase-shift modulated zero-voltage and zero-current switching (ZVZCS) series resonant converter (SRC) was proposed for constant current (CC) and constant voltage (CV) charging operating at the series resonant frequency. Wide output voltage range is achieved by adjusting the duty cycle of the primary inverter for CC charging and unity gain is for CV charging at full duty cycle. By tuning resonant tank parameters, discontinuous conduction mode (DCM) and boundary conduction mode (BCM) are obtained in CC charging and CV charging, respectively, which ensures zero-current switching (ZCS) of rectifier diodes and nearly ZCS of leading leg in whole charging profile. Meanwhile, a constant triangular current provided by a novel auxiliary circuit is used to implement zero-voltage switching (ZVS) for all primary MOSFETs with a reduced conduction loss. The auxiliary current is independent of duty cycle and load variation. Compared with the conventional ZVZCS phase-shift full-bridge converter with capacitive output filter, smaller conduction loss and turn-off loss can be obtained in battery charging profile. Detailed circuit operation principles and model analysis are presented. A 100 kHz/1 kW prototype is built to verify the performance.