Series Resonance Research Articles

Determination of Electrical and Mechanical Properties of Liquids Using a Resonator with a Longitudinal Electric Field

The possibility of determining the elastic modules, viscosity coefficients, dielectric constant and electrical conductivity of a viscous conducting liquid using a piezoelectric resonator with a longitudinal electric field is shown. For the research, we chose a piezoelectric resonator made on an AT-cut quartz plate with round electrodes, operating with a shear acoustic mode at a frequency of about 4.4 MHz. The resonator was fixed to the bottom of a 30 mL liquid container. The samples of a mixture of glycerol and water with different viscosity and conductivity were used as test liquids. First, the frequency dependences of the real and imaginary parts of the electrical impedance of a free resonator were measured and, using the Mason electromechanical circuit, the elastic module, viscosity coefficient, piezoelectric constant and dielectric constant of the resonator material (quartz) were determined. Then, the container was filled with the test sample of a liquid mixture so that the resonator was completely covered with liquid, and the measurement of the frequency dependences of the real and imaginary parts of the electrical impedance of the loaded resonator was repeated. The dependences of the frequency of parallel and series resonances, as well as the maximum values of the electrical impedance and admittance on the conductivity of liquids for various viscosity values, were plotted. It was shown that these dependences can be used to unambiguously determine the viscosity and conductivity of the test liquid. Next, by fitting the theoretical frequency dependences of the real and imaginary parts of the electrical impedance of the resonator loaded with the liquid under study to the experimental dependences, the elastic module of the liquid and its dielectric constant were determined.

Investigation of the doubly excited [formula omitted] resonance series in C[formula omitted] ion

We investigate in the present paper the doubly excited 1Po states in the C4+ ion. We report highly accurate results of their energy positions in the energy spectrum, their lifetimes and the x-ray photon energies required to populate them and observe their autoionization. The results were obtained by using our B-spline based spectral approach combined with the complex rotation method that has proven its effectiveness in the detection of the doubly excited states in the O6+[1] and Li+[2] ions. We also report in the paper the first results on the characterization and identification of the states that share similar angular correlation pattern, which allows their classification into distinct resonance series.

Maze-Based Scalable Wireless Power Transmission Experimental Arena for Freely Moving Small Animals Applications.

This paper presents an innovative T/Y-maze-based wireless power transmission (WPT) system designed to monitor spatial reference memory and learning behavior in freely moving rats. The system facilitates uninterrupted optical/electrical stimulation and neural recording experiments through the integration of wireless headstages or implants in T/Y maze setups. Utilizing an array of resonators covering the entire underneath of the mazes, the wireless platform ensures scalability with various configurations. The array is designed to ensure a natural localization mechanism to localize the Tx power toward the location of the Rx coil. The system is analyzed and modeled using ANSYS HFSS software to optimize design. The primary goal was to achieve uniform wireless power delivery throughout the mazes through a comparative study of different transmitter (Tx) array configurations, such as float, series, and parallel resonators. The calculated Specific Absorption Rate (SAR) in rat tissue model equals 1.7 W/kg at the power carrier frequency of 13.56 MHz. A prototype of the proposed maze-based WPT design, featuring 8 Tx resonators, a Tx coil and power amplifier, and a headstage power harvesting unit, is successfully implemented and its performance characterized for all three resonator configurations. The implemented T maze-based WPT system has a total length of 128 cm. In the overlapping Tx resonators configuration, a homogeneity of 94% is achieved for the measured power transfer efficiency at over 30%, while continuously delivering over 60 mW for series configuration.

Dual-frequency transmitter configuration for shallow surface electromagnetic detection

In shallow surface electromagnetic detection, the square wave scheme is generally used in conventional transmission systems. Based on frequency-domain electromagnetic sounding theory, high-frequency measurement helps to improve vertical resolution. However, long grounded cable inductance produces severe reactive power suppression at high frequency transmission frequencies, which will reduce detection. To further improve detection accuracy and efficiency, a dual-frequency transmitter configuration is proposed in this article for shallow surface detection. The transmitter simultaneously powers two LC series resonant circuits for the detection of shallow and deep area. Dual-frequency control strategy is adopted, with both bridge arms being provided with constant switching frequency operation. According to the equivalent model of the transmission system, the control of the load branches is independent of each other. The LC series resonant circuit guarantees a wide passband to match long cable inductance that cannot be accurately estimated in advance. Simulations and experimental tests were carried out using this transmitter configuration and control technique. The simulation and experimental results are in general agreement, verifying the feasibility and effectiveness of the proposed dual-band transmitter configuration.

Birefringent optical responses of single-chirality carbon nanotube membranes

Membranes composed of single-walled carbon nanotubes (SWCNTs) with a specific chiral structure (chirality) possess unique optical properties dominated by thermally robust quasi-one-dimensional excitons. Therefore they have emerged as promising materials for photonic and/or thermo-optic applications. As SWCNTs in the membranes are usually aligned two-dimensionally in a plane, and the optical responses of individual SWCNTs are highly anisotropic, the macroscopic responses of membranes are expected to depend on the light-propagation direction. However, the complex refractive-index spectra of some membrane axes are unknown, hindering the optical design of SWCNT-based devices that respond to arbitrarily propagating light. Here, we report the anisotropic complex refractive index spectra of a single-chirality SWCNT membrane fabricated via vacuum filtration. The polarization- and angle-resolved reflection spectra were obtained in the near-infrared-to-visible region. All spectral features in different polarizations and incident angle configurations were consistent with a uniaxial birefringent membrane, reflecting the random in-plane orientations of the SWCNTs. The ordinary (in-plane) refractive index spectra presented a series of sharp resonances of parallel-polarized excitons. The extraordinary (out-of-plane) refractive index in the 0.8–2.4 eV range was determined as ∼1.9. The extraordinary spectra included small but indispensable contributions from the cross-polarized exciton resonance, which are necessary for properly predicting the angle-dependent optical responses of the membrane. By completely unveiling the birefringent optical responses of single-chirality SWCNT membranes, this work paves the way for integrating SWNCT membranes into precise and diverse photonic and/or thermo-optic devices.

Compact RF transmission unit for nuclear quadrupole resonance spectroscopy

Nuclear quadrupole resonance (NQR) spectroscopy is a non-destructive measurement technique that enables to detect materials of interest very accurately. This technique works by sending high power electromagnetic waves with radio frequency (RF) very specific to the molecular structure to excite the sample and detecting the respond signal with the same frequency. Portable NQR detectors can be potentially developed to detect explosives with non-metallic containers in the fields. However, commercial RF high power amplifiers are large and heavy, so they are not practical for field usage. In this work, we demonstrate a compact NQR transmission part which composed of an active input signal conditioner, a class-D amplifier, and an NQR coil. The active input signal conditioner circuit will convert a single rf pulse with low amplitude (<0.5Vp) to two pulses (with 180° phase difference) and they are subsequently amplified to TTL level. In the class-D amplifier, the pre-amplified pulses are further amplified by a high voltage gate driver IC to 24V amplitude. These high voltage pulses are converted to a single 24V pulse by MOSFETs connected in a half bridge configuration. Finally, the amplified pulse is fed to the NQR coil, i.e., a low impedance LC series resonance circuit. The voltage across the coil at resonance frequency is about 1kVpp.

Similarity laws for two-dimensional simulations of low-pressure capacitively coupled radio-frequency discharges

Similarity laws (SLs) for low-pressure capacitive radio-frequency plasmas are generalized from one- to two-dimensional (2D) frameworks based on kinetic particle-in-cell simulations. Fundamental discharge parameters, such as the 2D distributions of electron densities and electric fields, are examined to assess the applicability of SLs to such discharges. The discharge characteristics are found to remain invariant when external control parameters are changed according to SLs. Even under conditions where nonlinear electron resonance heating caused by the self-excitation of the plasma series resonance due to the geometric reactor asymmetry plays an important role, the electron kinetics are shown to be invariant. Moreover, the validity of SLs for the ion dynamics is demonstrated. The results advance the applicability of SLs to a 2D cylindrical reactor geometry with azimuthal symmetry, indicating broad application prospects in practice.

Study on the interaction of vehicle-to-grid and its impact on power quality of electric grid

With the continuous increase in the number of electric vehicles (EVs) in the market, both EVs and charging stations are rapidly developing. This paper provides an overview of the negative impacts of EV charging on the distribution grid at the current stage. It summarizes specific solutions proposed by scholars both domestically and internationally to address the effects on voltage, harmonics, and power quality. These solutions mainly involve the addition of filters to the distribution grid, the use of 12-pulse rectifiers, and series resonance. Furthermore, the paper analyzes how Vehicle-to-Grid (V2G) technology can balance the grid and regulate power quality issues caused by EV charging, ensuring stable system operation. V2G technology also enables EVs to function as mobile energy storage devices and allows for rational energy distribution using bidirectional charging stations. The integration of charging stations with the grid, forming a connected vehicle network, is considered the future direction of EV development.

Design Procedure for a High-Efficiency Class-E/F3 Power Amplifier

The switch voltage stress in a Class-E power amplifier (PA) is larger than that in any other switching PAs. A series resonant filter is added across the switch to filter out the third harmonic of the switch voltage and reduce the switch voltage stress. The new circuit is usually called a Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA. The output power, the efficiency, and the component values of a Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA can be <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sensiti</b> ve to the design of the harmonic filter. In this article, we perform a sensitivity analysis on Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA and provide guideline to design a Class-E/F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PA which is robust against variations in the harmonic filter components. We also provide new design equations to calculate the component values. To validate the proposed design guidelines and equations, a prototype circuit was designed and implemented. At <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> = 4.5 V, the measured output power, the efficiency, and the switching frequency of the prototype PA were 0.96 W, 94.2%, and 800 kHz, respectively.

High-resolution nanoscale NMR for arbitrary magnetic fields

Nitrogen vacancy (NV) centers are a major platform for the detection of nuclear magnetic resonance (NMR) signals at the nanoscale. To overcome the intrinsic electron spin lifetime limit in spectral resolution, a heterodyne detection approach is widely used. However, application of this technique at high magnetic fields is yet an unsolved problem. Here, we introduce a heterodyne detection method utilizing a series of phase coherent electron nuclear double resonance sensing blocks, thus eliminating the numerous Rabi microwave pulses required in the detection. Our detection protocol can be extended to high magnetic fields, allowing chemical shift resolution in NMR experiments. We demonstrate this principle on a weakly coupled 13C nuclear spin in the bath surrounding single NV centers, and compare the results to existing heterodyne protocols. Additionally, we identify the combination of NV-spin-initialization infidelity and strong sensor-target-coupling as linewidth-limiting decoherence source, paving the way towards high-field heterodyne NMR protocols with chemical resolution.

An Innovative Design Approach for Resonant DC/AC Converters, Based on Symmetry in Their Operating Modes

The manuscript presents an innovative approach for the engineering design of resonant DC/AC converters used as sources of high-frequency electricity for a variety of needs: industrial and domestic applications, wireless power transmission, high-performance lighting, and more. The methodology is based on the generalized consideration of electromagnetic processes in a series resonant RLC circuit fed by a square-wave voltage source. Due to the symmetry in the form of the current in the AC circuit of the DC/AC converter, it is possible to generalize all their possible operating modes. This was realized by applying the quasi-boundary method to the analysis of resonant DC/AC converters with and without reverse diodes operating in soft and hard switching modes. On this basis, the transfer functions of the devices, which give the relationship between their output and input voltages, are defined and analytically determined. Additionally considered are cases of resonant DC/AC converters with complex output circuits, which are applied to match the load needs and the capabilities of the power electronic device. In this sense, the basic dependencies for designing the main types of resonant DC/AC converters using series and parallel load compensation are given. The effectiveness of the proposed methods is demonstrated through several examples, and their verification and validation is achieved with simulations and prototypes. The proposed innovative design approach is applicable not only in power electronics education, but also in the design and prototyping of a whole class of power electronic devices. The unification of design methodologies formalizes and algorithmizes the design process, which is an important step for its automation and for applying various optimization procedures to achieve certain goals.

Design of multi-frequency point, high-isolation switches for micro-channel plate data acquisition.

In order to replace the phosphor screen of a proximity-gated x-ray framing camera with a readout circuit using a time-interleaved structure, this paper carries out the design of a high-isolation RF switch. In this paper, a Metal-Oxide-Semiconductor Field Effect Tube (MOSFET) switching circuit is designed to achieve high isolation and low insertion loss at 0.5-3GHz. This solves the problem that the switching circuit cannot be turned off properly due to the parasitic capacitance of MOSFETs in the process of RF signal transmission, resulting in signal feedthrough. It also ensures that the input signal can be transmitted to the output intact when the switching circuit is turned on. High isolation is achieved by using parallel resonance to increase the voltage division and series resonance to leak the current. The switch achieves 76 dB isolation and 0.07 dB insertion loss at 1GHz frequency. Isolation is increased by adding parallel branches near the 2 and 3GHz frequency points, achieving greater than 33 dB isolation from 0.5 to 3GHz.

Implementation and Control of Multiport Grid Integrated Hybrid Energy Interface for EV Charging Application

EV charging combined with distributed energy storage (ES) devices could be utilized to send power to the grid during peak hours, mitigating the effects of load shedding. In order to achieve these goals, a hybrid multi-port charging system is developed in this study to properly manage power flows and balance energy. It is made up of a PFC bridge rectifier that is linked to an isolated three-port dc-dc converter that includes a series resonant (SRC) and a DAB converter for fast and slow charging applications, respectively. To maximize efficiency and power density, the ports share a 400 V common DC link. Grid-to-vehicle (G2V) mode is used to charge EV and ES vehicles from the utility grid; PV-to-grid (PV2G) mode is used to deliver PV energy to the grid; renewable-to-vehicle (R2V) mode is used to charge EV and ES batteries; and vehicle-to-grid (V2G) mode is used by EV and ES to deliver stored energy to the grid. The charging system’s performance and operation are validated in real time using MATLAB/Simulink under various operating situations. The system’s total harmonic distortion (THD) for the supply current is 2.07%. The suggested system is also compared against a state-of-the-art multiport charging system to assess its performance.

A New Class of Nonlinear Resonance Networks Modeled by Levinson–Smith and Liénard Equations

We propose a new class of nonlinear resonance networks which are modeled by standard second-order nonlinear differential equations of the Levinson-Smith type or its subset, the Liénard type. In particular, we modify series and parallel RLC resonance networks such that the passive resistor in these networks is composed of a fixed part and a variable voltage-or current-controlled part. The variable resistor is then made controllable by one of the circuit’s state-space variables leading to an embedded self feedback control mechanism. A possible discrete component circuit realizing the proposed concept is presented along with its simulations and experimental verification. The filter response behavior of one of the modified series resonance circuits is also experimentally verified using a Field Programmable Analog Array.

Soft-Switching Resonant DC Transformer for Class-D Switching Amplifier With Symmetric Bipolar Outputs

In this letter, soft-switching resonant DC transformer (DCX) for the class-D switching amplifier with the symmetric bipolar outputs is proposed. The proposed DCX consists of a single transformer primary inverter circuit and two transformer secondary dual series resonant half-bridge rectifier circuits, which reduces the voltage stress of the rectifier diodes. In the proposed DCX, the duty cycle of the primary inverter circuit is 0.5, and the symmetric bipolar output voltage gains only depend on the transformer. By dual series resonance between the leakage inductance and the output resonant capacitors, ZVS turn-on of switches and ZCS turn-off of the diodes can be achieved, which improves the overall efficiency. The characteristic of the DCX is elaborated and analyzed in this letter. Finally, a 60 W prototype is established and the experimental verified the theoretical analysis of the proposed DCX.

Compact high-efficiency energy harvesting positive and negative DC supplies voltage for battery-less CMOS receiver

In this paper, novel compact high-efficiency multi-band rectifiers that supply positive and negative output voltages are demonstrated for energy harvesting applications. The proposed voltage doubler circuits are used as real DC voltage supplies of radio frequency mm-wave CMOS receivers. Operating multi-band rectifiers have a complicated structure that required more resonance networks to force the rectifier to work in multi-band. Novel series and parallel resonance networks are implemented to force the rectifier to operate in dual-band at frequencies of 850 and 1400 MHz. The proposed resonance network eliminates the Schottky diode impedance variation as the input power or frequency changes and supports the impedance matching and minimizes the insertion loss. A novel high-quality sine-shape micro-strip inductor that obtains a quality factor above 65 over the frequency band from 200 to 1400 MHz and inductance equal to 14 ± 2 nH is designed to improve efficiency and enhance performance at low power levels. The first suggested RF voltage doubler rectifier with series resonance feedback between the input and cathode of the diode and parallel resonance operates at two frequency bands of 850 and 1400 MHz and obtains a peak conversion efficiency of 59%, a saturated output DC voltage is 2.5 V, and the conversion efficiency is 40% at RF-input-power of − 10 dBm. This voltage doubler achieves the required DC supply parameter (1.1 V and 450 uA) for biasing the mm-wave receiver at an RF input power of 0 dBm. Otherwise, the second suggested negative voltage rectifier has a maximum simulated conversion efficiency of 65%, saturated negative DC-voltage is − 3.5 V, and the conversion efficiency is 45% at an RF input power of − 10 dBm. The negative voltage rectifier obtains DC supply parameters (− 0.5 V and no current condition used for a gate bias) at − 10 dBm input power.

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.

Decoupled Mitigation Control of Series Resonance and Harmonic Load Current for HAPFs With a Modified Two-Step Virtual Impedance Shaping

Hybrid active power filter (HAPF) with large series capacitor can reduce the rating of power converter, but it is associated with the risk of low frequency <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance. The overlapping of series <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance frequencies and the dominated load harmonic current frequencies makes the conventional active damping approaches less effective. To overcome this challenge, a two-step harmonic virtual impedance control approach is developed to compensate the load harmonic current and reshape the closed-loop equivalent circuit of the HAPF for resonance damping. First, the shunt capacitor harmonic voltage is regulated according to a term that is associated with both the harmonic load current and the HAPF harmonic line current. Further investigation on the equivalent circuit transformations indicates that HAPF is equivalent to a controlled current source to compensate for load harmonic current and a virtual harmonic damping resistor between the series capacitor and grid impedance. Accordingly, the resonance damping and the nonlinear load low order harmonic current compensation can be well decoupled with minimal interference.

Series resonance effects of a variable inductor termination on the nonpowered electrode in capacitively coupled plasmas

The effect of LC series resonance on the voltage of a nonpowered electrode in a capacitively coupled plasma is investigated by connecting a variable inductor to the nonpowered electrode. Two distinct LC series resonances are observed while varying the reactance of the variable inductor. The first resonance occurs between an inductor and a vacuum variable capacitor, thereby resulting in the voltage of the nonpowered electrode approaching zero. The reactance between the inductor and the vacuum variable capacitor is minimized at this resonance, thereby enabling the nonpowered electrode voltage to remain close to 0 V even with increased applied RF power. The second resonance is a series resonance between the variable inductor and the nonpowered electrode sheath, leading to a maximization of the nonpowered electrode voltage. The reactance between the variable inductor and the nonpowered electrode sheath is minimized at this resonance. As the applied RF power increases under the second resonance condition, the voltage of the nonpowered electrode increases, thereby resulting in a significant increase in the maximum electron density by approximately 35%. This increase in the electron density at the second resonance can be attributed to enhanced stochastic heating due to the sharp increase in the sheath voltage.

A New Doherty Combiner with Wide Bandwidth for Magnitude and Phase Balance Compensation

This paper proposes a novel Doherty combiner that uses a series and parallel resonant circuit for wideband. Unlike conventional combiners, the aim of the proposed combiners is to extend bandwidth for not only the magnitude bandwidth, but also phase balance by employing series and parallel resonant circuits at the output impedance of the peaking amplifier. Considering the load impedance of the peaking amplifier, the Doherty combiners were analyzed in the theory of this study by deriving the series and parallel resonant circuit values. The output phase balances are determined for the targeted bandwidth to achieve uniform phase balance in the proposed combiner I using a series resonator. For better magnitude bandwidth, the slope of reflection coefficient (Γ) at port 3 in the combiner II using series resonator was derived using the derivative of Γ with respect to ω. Experimental results show that the proposed combiner I has 63.5% magnitude fractional bandwidth (FBW) and 118% FBW with the phase balance at ±2.5°. The proposed combiner II also has 85% magnitude FBW and 118% FBW with the phase balance at ±2.5°.