Series Resonant Frequency Research Articles

A Contribution to the Frequency Analysis and Transient Response of Power Transformer Windings

—This article proposes a new approach to study the frequency response and the transient analysis of power transformer windings. For improved accuracy, the suggested model includes, among other equivalent circuit elements, the mutual magnetic couplings between any winding turn and all others. This implies that the equivalent inductance of any considered turn will be a location-dependent parameter. Accordingly, the winding will be analyzed as a non-uniform transmission line. Through the application of a recursive circuit reduction technique, a closed-form Laplace s-domain analytical expression for the winding's input impedance can be obtained for any neutral treatment. The resulting expression can be used to determine the winding's series and parallel resonance frequencies. The s-domain expression for the input impedance, in connection with the numerical inverse Laplace transform, will be utilized for determination of the winding's time-domain transient response for any input voltage or current time waveform. Accuracy increases with the assumed number of winding sections, which can be even increased to the actual number of turns, limited only by the available computation resources. The results of case studies are in good agreement with those available in the literature using the time-domain solution of the simultaneous differential equations in the state variables.

Quartz force sensor and facing spiral coils for noncontact detection

A noncontact detectable force sensor is a promising technique for monitoring the defects of a structural object, such as buildings and bridges, and medical surgery devices. In this study, the noncontact detectable force sensor with an AT-cut quartz crystal resonator and a pair of spiral coils is proposed. The thickness-shear mode is excited with energy trapping excitation. The resonant frequency of this vibration mode is a function of the applied external force because of the nonlinear elastic module. Then, from the resonant frequency change of the quartz crystal, the input force can be measured. Admittance characteristics of this sensor contained series and parallel resonance. We confirmed that noncontact detection of the resonant frequency change is possible by using two facing spiral coils. The coil gap effect could be eliminated by calculating the difference between the series and parallel resonant frequencies.

Effect of growth conditions on microstructure of BiFeO3-0.33BaTiO3 films and performance of bulk acoustic wave resonators

The effect of growth conditions on the microstructure of BiFeO3-0.33BaTiO3 (BF-BT) films and the performance of bulk acoustic wave (BAW) resonators is analyzed using test structures with the BF-BT films grown at different positions relative to the plume axis in the pulsed laser deposition system. The BF-BT film grain size and surface roughness reveal a strong asymmetric surface distribution and decrease significantly in the film region facing the laser beam-plume interaction area. The (100) BF-BT texturing is enhanced in this film region. The variations in the BF-BT film microstructure result in corresponding variations of the BAW resonator performance. Their correlations are established using the model of the roughness induced attenuation of the reflected acoustic waves and theory of the dc field induced piezoelectric effect. The BAW resonators with the highest parameters are obtained in the BF-BT film region facing the laser beam-plume interaction area. The BAW resonators located in this film region reveal a mechanical Q-factor of 200 at 4.2 GHz, an effective electromechanical coupling coefficient of 10% and a tunability of the series resonance frequency of 4.5%.

Analysis and implementation of a zero‐voltage switching pulse‐width modulation resonant converter

This study presents an interleaved pulse-width modulation (PWM) converter to achieve the functions of zero-voltage switching (ZVS) for all power switches and zero-current switching (ZCS) for rectifier diodes at the secondary side. A three-level hybrid DC converter is adopted to reduce the voltage stress of power switched at one-half of the DC bus voltage and automatically balance the two input capacitor voltages. Therefore MOSFETs with 600 V voltage stress can be used at the second stage DC/DC converter after the three-phase power factor correction circuit. The fixed frequency PWM is used in three-level PWM resonant converter to regulate output voltage. Since the selected switching frequency is less than the series resonant frequency, MOSFETs can be turned on at ZVS and rectifier diodes can be turned off at ZCS. Thus, the switching losses of power switches are reduced and the reverse recovery losses of rectifier diodes are eliminated. Interleaved PWM scheme is adopted to share load current and further cancel current ripple at output capacitor side. Thus, output capacitance can be reduced. Finally, experiments are provided to verify the effectiveness of the proposed converter.

Parameterization of Three-Phase Electric Machine Models for EMI Simulation

A systematic and practical method to parameterize three-phase electric machine models for electromagnetic interference (EMI) simulation is presented. The proposed behavioral model consists of multiple sections of linear RLC circuits and is intended for time-domain simulation with inverters and other power electronic circuits found in typical motor drive systems. The proposed parameterization method uses a differential-mode (DM) and a common-mode (CM) impedance measurement of the machine and takes advantage of the separation among different parallel and series resonant frequencies of each impedance to determine the parameters of each stage in a noniterative manner. The proposed method can also be applied to model three-phase cables and transformers.

Application of a C-Type Filter Based LCFL Output Filter to Shunt Active Power Filters

This paper proposes and designs a new output filter called an LCFL filter for application to three phase three wire shunt active power filters (SAPF). This LCFL filter is derived from a traditional LCL filter by replacing its capacitor with a C-type filter, and then constructing an L-C-type Filter-L (LCFL) topology. The LCFL filter can provide better switching ripple attenuation capability than traditional passive damped LCL filters. The LC branch series resonant frequency of the LCFL filter is set at the switching frequency, which can bypass most of the switching harmonic current generated by a SAPF converter. As a result, the power losses in the damping resistor of the LCFL filter can be reduced when compared to traditional passive damped LCL filters. The principle and parameter design of the LCFL filter are presented in this paper, as well as a comparison to traditional passive damped LCL filters. Simulation and experimental results are presented to validate the theoretical analyses and effectiveness of the LCFL filter.

Capacitive-Coupling-Based Information Transmission System for Implantable Devices: Investigation of Transmission Mechanism

Many medical electronic devices that can be implanted deep inside the body have been developed recently. These devices are designed to transmit the information that is collected inside the body to receiving antennas outside the body. In this work, we examine a method that uses a high-frequency current in the transmitting electrodes of the implanted device for the transmission of information to receiving electrodes attached to the body surface. To investigate the transmission mechanism and the factors that determines the optimum frequency, the output voltage V2 and the input and output impedance ( Zin and Zout) were analyzed by conducting a finite-difference time-domain electromagnetic simulation. The results clearly show that the receiving part (electrodes and wire), including biological tissue, acts as a loop antenna. The maximum V2 value was obtained at the first parallel resonance frequency of Zout at 370 MHz under a load resistance of 1 MΩ. In contrast, the output current of the source increased at the series resonance frequency of Zin. The series resonance frequency could be adjusted to move a target frequency by adding an inductance between the source and the transmitting electrodes.

Intrinsically Switchable Ferroelectric Contour Mode Resonators

This paper presents the design and measurement results of intrinsically switchable interdigitated contour mode resonators based on barium titanate (BTO) thin films. The resonators have lithographically defined interdigitated electrodes that determine their resonance frequencies. The BTO thin film exhibits electrostriction, which allows the resonances to be switched on and off. The highest frequency device exhibits series and parallel resonance frequencies of 1.67 and 1.68 GHz and quality factors of 178 and 152, respectively, with the application of a 10-V dc bias. Resonances are turned off by removing the dc bias. This is the first demonstration of an intrinsically switchable interdigitated ferroelectric contour mode resonator.

Ultrahigh-Resolution MEMS Humidity Sensing Elements Based on Film Bulk Acoustic Wave Resonators

A high-resolution humidity sensor based on MEMS FBAR with spin-coated PVA thin film is reported. The sensors exhibit very high sensitivity to water vapor and are able to detect down to 0.08 % change in relative humidity by monitoring the shift in series resonant frequency of the FBARs. The integration of these devices with CMOS oscillating circuits and RF front-end chips will create great potential of FBAR based mass sensors in a wide variety of applications in chemical and biological sensing.

Electrical matching of low power piezoelectric ultrasonic transducers for microelectronic bonding

The electrical matching of low power piezoelectric ultrasonic transducers for microelectronic bonding is studied in this paper. The admittance characteristics of the transducers are described through admittance circle diagrams and the electrical matching analysis for the transducers is presented. The frequency ratio function has been introduced and analyzed. The result shows that the frequency ratio function increases with the static capacitance, dynamic capacitance and dynamic resistance, and decreases with the dynamic inductance. When the static capacitance, dynamic capacitance, dynamic resistance and dynamic inductance are small, there are little differences between the resonance frequency and the series resonance frequency, and it is not necessary to operate electrical matching when the frequency ratio function is less than 0.001. A typical low power piezoelectric transducer used in microelectronic bonding has been adopted to verify the results of electrical matching analysis. The analysis and experimental results show that the transducer can work well at its vibration frequency without electrical matching.

Enhanced tunable performance of high Q-factor BaxSr1−xTiO3 film bulk acoustic wave resonators

Emerging intrinsically tunable film bulk acoustic wave(BAW) resonators allow the development of new generation reconfigurable and agile microwave circuits. In this paper, we demonstrate the enhancement of tunable performance of the high Q-factor BaxSr1−xTiO3 BAW – solidly mounted resonators (BAW–SMR) by varying Ba concentration. The Ba0.5Sr0.5TiO3 BAW–SMR reveal tunability of series resonance frequency up to 2.4%, electromechanical coupling coefficient up to 7.5% and rather high Q-factor, up to 250 at 5.3 GHz. Correlations between the measured electroacoustic parameters are analyzed using the theory of dc field-induced piezoelectric effect in paraelectric phase ferroelectrics. Higher coupling coefficient and tunability of resonance frequency of the Ba0.5Sr0.5TiO3 BAW–SMR are associated with higher tunability of permittivity. Strong anisotropy in field-induced piezoelectric effect is predicted with highest coupling coefficient in (001) direction of the BaxSr1−xTiO3 films. It is also shown that the tunability of series resonance frequency of Ba0.5Sr0.5TiO3 BAW–SMR is limited by relatively high and negative nonlinear electrostriction coefficient which is found to be m ≈ −4·1010 m/F. The BAW–SMR Q-factor is limited significantly by extrinsic acoustic loss associated with wave scattering at reflection from relatively rough top interface. The results of analysis show possible ways of further improvement of the performance of tunable BAW–SMR.

Comparison between piezoelectric material properties obtained by using low-voltage magnitude frequency sweeping and high-level short impulse signals

Determination of electromechanical piezoceramic material parameters is usually done by fitting the measured input electrical impedance of the piezoceramic sample to the theoretical modelling equation for the input electrical impedance of the unloaded free piezoceramic resonator. The input electrical impedance of the sample is usually measured by using low voltage or current magnitude frequency sweeping signals. In this work, the complex material parameters of piezoceramic samples are determined in the real operating conditions by using the high voltage short impulse excitation signals.The input electrical impedance determined in the impulse mode around thickness extensional vibration mode (TE) and calculated piezoceramic parameters (clamped dielectric permittivity, electromechanical coupling factor, elastic stiffness and piezoelectric constant) are compared to the results obtained by using the low voltage magnitude frequency sweeping signals. When impulse excitation is used, the series resonance frequency is decreased and the input electrical impedance magnitude at series resonance is increased, which means that overall losses included in the piezoceramic parameters are increased.The complex material parameters obtained from the input electrical impedances determined by using the low voltage magnitude sweeping signal and high level short impulse signals are included in the KLM theoretical model describing the piezoceramic sample behaviour around TE mode. Better agreement between measured and theoretically determined current magnitude response around TE mode has been obtained, in the KLM model, when piezoceramic parameters determined by using the impulse signal excitations are included in the modelling.The physical reason for increase of the losses in piezoceramic material could lie in the fact that the ferroelectric domains in the piezoceramic respond harder on very short impulse excitation signals than on continuous frequency sweeping signals which are usually used in determination of piezoelectric material parameters.

Design and Simulation of Film Bulk Acoustic Wave Resonator in Ku-Band

This paper presents the design of a Film Bulk Acoustic Wave Resonators (FBARs) operating in Ku-band. The one-dimensional (1-D) numerical and the three-dimension (3-D) Finite Element Method (FEM) simulation results are analysed and compared. The results show that coupling coefficient (k2eff) up to 6.5% can be obtained with optimised thickness ratio of electrode/piezoelectric layers of operating frequencies greater than 15GHz. The FBARs have areas of 1.69x10-4µm2and 7.84x10-4µm2for series resonance frequency of 14.7GHz and 15.9GHz respectively and achieves quality (Q) factor of 300. The designed FBAR filter operating in Ku-band has the centre frequency of 15.5 GHz, the insertion loss of 3.5dB, out-of-band rejection of 13dB and fractional bandwidth of 6.6%.

Micromachined One-Port Aluminum Nitride Lamb Wave Resonators Utilizing the Lowest-Order Symmetric Mode

The characteristics of one-port aluminum nitride (AlN) Lamb wave resonators utilizing the lowest-order symmetric mode with electrically open, grounded, and floating bottom electrode configurations are theoretically and experimentally investigated in this paper. Finite element analysis is performed to take an insight into the static capacitance characteristics of the AlN Lamb wave resonators with various bottom surface conditions. Without sacrificing the transduction efficiency, the floating bottom electrode is capable of reducing the static capacitance in the AlN thin plate and then promotes an efficient improvement in the effective coupling coefficient (k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ). In addition, in comparison with the grounded bottom electrode, the employment of the floating bottom electrode offers simple fabrication processes for the micromachined Lamb wave resonators. Experimentally, the AlN Lamb wave resonators without the bottom electrode exhibit an average loaded quality factor (Q) as high as 2676 at the series resonance frequency, but a low average k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> of 0.19%. On the contrary, the Lamb wave resonators with the electrically floating bottom electrode show the largest average k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> up to 1.13% among the three topologies but a low average loaded Q of 800 at the series resonance frequency. In contrast to the floating bottom electrode, the Lamb wave resonators with the electrically grounded bottom electrode show a smaller average k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> of 0.78% and a similar average loaded Q of 758 at the series resonance frequency.

Tunable Ba0.5Sr0.5TiO3 film bulk acoustic resonators using SiO2/Mo Bragg reflectors

Tunable and switchable Ba0.5Sr0.5TiO3 film bulk acoustic resonators (FBARs) based on SiO2/Mo Bragg reflectors are explored, which can withstand high temperature for the deposition of BaxSr1−xTiO3 (BST) films at 800 °C. The dc bias-dependent resonance may be attributed to the piezoelectricity of the BST film induced by an electrostrictive effect. The series resonant frequency is strongly dc bias-dependent and shifts downwards with dc bias increasing, while the parallel resonant frequency is only weakly dc bias-dependent and slightly shifts upwards at low dc bias (< 45 V) while downwards at higher dc bias. The calculated relative tunability of shifts at series resonance frequency is around −2.3% and the electromechanical coupling coefficient is up to approximately 8.09% at 60-V dc bias, which can be comparable to AlN FBARs. This suggests that a high-quality tunable BST FBAR device can be achieved through the use of molybdenum (Mo) as the high acoustic impedance layer in a Bragg reflector, which not only provides excellent acoustic isolation from the substrate, but also improves the crystallinity of BST films withstanding higher deposition temperature.

Optimization on Thin Film Bulk Acoustic Resonator (FBAR) by Transmitting Line Method

In this paper, the transmitting line method is applied to analyze the properties of FBAR, and the input impedance equation is obtained, and the series resonance frequency fs and the parallel resonance frequency fp are calculated by this method. Moreover, the elastic effects of the electrode on the effective electromechanical coupling factor, k2eff , and the resonance factor, Qs&gt; , of FBAR are investigated by the transmitting line method. Results indicate that the acoustic impedance ratio of the electrode to the piezo-film dominantly determines the behaviors of the k2eff , the variation of Qs versus the thickness of the electrode crucially depends on the acoustic impedance ratio of electrode to piezoelectric films. The results will be applied in the theoretical optimization of FBAR, which are available to optimize the fabrications of FBARs and similar devices.

Autoswitching LED Driver

A novel autoswitching Class D converter is proposed as a means to power an LED light engine. The control system regulates the LED current by adjusting the series resonant frequency. The control transformer provides intrinsic isolation between the power converter and the 0-10 V dimming interface. An innovative thermal fold-back method limits the maximum temperature of the driver and the LED array. The autoswitching methodology and the control methodology are presented in detail. The experimental model achieves an efficiency of greater than 93% at 277 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AC</sub> while producing 100 W of output power. The light engine is dimmable to less than 10% of the rated output current. A new miswiring protection circuit does not use a thermistor and provides excellent linearity in the 0-10 V dimming interface.

Interleaved ZVS Resonant Converter with a Parallel-Series Connection

This paper presents an interleaved resonant converter with a parallel-series transformer connection in order to achieve ripple current reduction at the output capacitor, zero voltage turn-on for the active switches, zero current turn-off for the rectifier diodes, less voltage stress on the rectifier diodes, and less current stress on the transformer primary windings. The primary windings of the two transformers are connected in parallel in order to share the input current and to reduce the root-mean-square (rms) current on the primary windings. The secondary windings of the two transformers are connected in series in order to ensure that the transformer primary currents are balanced. A full-wave diode rectifier is used at the output side to clamp the voltage stress of the rectifier diode at the output voltage. Two circuit modules are operated with the interleaved PWM scheme so that the input and output ripple currents are reduced. Based on the resonant behavior, all of the active switches are turned on under zero voltage switching (ZVS), and the rectifier diodes are turned off under zero current switching (ZCS) if the operating switching frequency is less than the series resonant frequency. Finally, experiments with a 1kW prototype are described to verify the effectiveness of the proposed converter.

The temperature effect on the resonant spectra of thin piezoelectric ceramic disk

This study examines the influence of the temperature on the low-frequency resonant spectrum of piezoelectric ceramics based on lead zirconate titanate solid solution Pb(Zr,Ti)O3-based piezoelectric ceramics with heat variations ranging from 25 to 150°C, concluding that temperature increases cause the resonant spectrum to shift to higher frequencies. Furthermore, the variation in fundamental series resonant frequency fs (with temperature variation) is larger than the variation of fundamental parallel resonant frequency fp (with temperature variation). Another result of increased temperature is the decrease in effective electromechanical coupling factor keff. Finally, the effect of temperature on the overtone mode is more obvious than that of the fundamental mode.

Dynamic properties of the polyethylene glycol molecules on the oscillating solid–liquid interface

The dynamic properties of polyethylene glycol (PEG) molecules on the solid–liquid interface oscillating at MHz were investigated using the quartz crystal microbalance (QCM). The number-average molecular weights (Mn) of the PEG molecules were systematically varied over 4 orders of magnitude. This study makes it clear that the series-resonant frequency shift, ΔF, of the QCM against the square root of the density–viscosity product of the PEG solution is linear and has the intercept. Moreover, systematical analysis reveals that the ΔF slope rapidly decreases with Mn and that the ΔF intercept becomes constant above 4.0×103gmol−1. As a result, those reveal that the resonant length of the PEG molecule moving with the oscillating plate of 9MHz is 54.2Å. We also find that the behaviors of ΔF due to Mn are mainly caused by the length of the PEG molecule.