Parallel Resonance Research Articles

Two-Phase Stator Vibration Amplitude Compensation of Traveling-Wave Ultrasonic Motor

The consistency of the two-phase mode responses is essential to ensure the mechanical performance and stability of traveling-wave ultrasonic motors. Due to the asymmetry of the stator, inevitable manufacturing errors, or imbalance of the excitation voltages, the amplitudes of the two-phase standing waves cannot be exactly the same, resulting in unstable operating of USM. To improve the stability of the motor and decrease the velocity fluctuation, a closed-loop velocity control scheme considering two-phase consistency compensation based on the vibration amplitude of the stator is proposed. This scheme is implemented under the framework of the stator vibration amplitude-based velocity control and parallel resonance frequency tracking (VCBVF). Based on the relationship between the velocity and stator vibration amplitude (SVA), two-phase excitation signals are adjusted individually and simultaneously. Compared with the single-phase feedback VCBVF control scheme, experimental results show that the proposed scheme can reduce the overshoot from 17.50% to 6.90% and velocity fluctuations from 7.69 rpm to 2.40 rpm, under different load torques. The proposed scheme can compensate for the two-phase electrical inconsistency and improve the velocity stability and output power of motor operation under various conditions.

A new adaptive parallel resonance system based on cascaded feedback model of vibrational resonance and stochastic resonance and its application in fault detection of rolling bearings

Accurate extraction of weak feature information in strong background noise is a key to detect and identify rolling bearing faults. Stochastic resonance (SR) and vibrational resonance (VR) have received extensive attention and research in weak signal detection by reason of their advantages of utilizing additional inputs (i.e. noise or high frequency harmonic signals) to enhance weak signals. Considering the advantages and disadvantages of SR and VR in weak signal detection, this paper combines the two to construct a cascaded feedback model of VR and SR, and utilize it to form a parallel resonance system, which improves the detection performance of weak signals through the ensemble average effect. Furthermore, a multi-parameter optimization strategy based on the improved whale optimization algorithm (WOA) is proposed for the parameter selection of the parallel resonance system. It uses the constructed measurement index independent of the prior knowledge as the fitness function to realize automatic adjustment of multi-parameter, and obtains the final output by weighted summation of the optimal results obtained by multiple iterations. Finally, the suggested method is analyzed by numerical simulation signal and experimental data of rolling bearings, and the effectiveness and superiority of the proposed method in the detection of weak fault features are verified.

Optimal allocation of power quality monitors considering short-duration voltage variations and parallel harmonic resonance conditions in power distribution systems

The proposed allocation methodology of Power Quality Monitors (PQMs) allows optimal monitoring of short-duration voltage variations and potential harmonic resonance conditions by defining strategic nodes in a Power Distribution System (PDS). The allocation methodology combines the Fault Position Method (FPM) and Harmonic Resonance Modal Analysis (HRMA) to obtain a binary covering matrix. The optimization process lately uses this matrix to determine the best installation nodes of the minimum number of PQMs that observe the considered power quality disturbances. From FPM, the remaining nodal voltages are studied for different short-circuits, which cause voltage sags and or swells. HRMA is used to calculate the modal impedances related to the critical modes and identify the respective harmonic frequencies of the PDS. The allocation problem is set as integer linear programming performed using a Branch and Bound algorithm. The proposed methodology was tested for 15 nodes PDS based on a CIGRÉ network and 24 nodes PDS derived from the IEEE 34 nodes test system. Results show that 2 to 4 PQMs are required for the 15 nodes PDS and 2 to 9 PQMs for the 34 nodes PDS to thoroughly observe the considered power quality disturbances.

Passive Current Sharing of a Multiphase Inverter Based on Parallel Resonance

To balance the phase output currents of a multiphase inverter, negatively coupled inductors (NCIs) can be used to achieve a larger differential mode (DM) loop impedance than the common mode (CM) loop impedance. For a good current sharing effect, the inductances of the NCIs should be large, leading to bulky size and cost ineffectiveness, which should be avoided in high-power applications. This article proposes a novel current balancing method based on parallel resonance. A parallel resonant network (PRN) is inserted between any two phases. With <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta $</tex-math></inline-formula> -Y transform, the inductor common point and the capacitor common point are generated, either of which can be used as the CM output node. For a series–series compensated wireless power transfer system, part of the existing compensating capacitance can be employed to form PRNs with the added parallel inductors. The DM currents are suppressed by the large impedance of the PRNs. Compared with the existing method, the inductances of the NCIs can be greatly reduced to achieve better current balancing performance. The added parallel inductors are of small current ratings, which are only visible to DM currents. A prototype is implemented to validate the proposed method.

Numerical study on influences of parallel sonic wave damping, precession, and bounce resonances on resistive wall modes in CFETR

Adopting an 11 MA steady-state reversed magnetic shear equilibrium of the China Fusion Engineering Test Reactor, the influence of parallel sonic wave damping, precession, and bounce resonances on the resistive wall mode (RWM) at different plasma pressures and plasma toroidal rotations is numerically investigated using the MARS-K code. We find that the parallel sonic wave damping, precession, and bounce resonances have damping effects on the RWM. The RWM is stabilized by the parallel sonic wave damping at low plasma pressure. At the two q = 3 rational surfaces, the RWM is the most unstable, but the precession resonance mainly occurs at one of the q = 3 rational surfaces, so the RWM cannot be stabilized. In addition, the precession resonance and bounce resonance occur simultaneously, and there are two roots. One is the precession resonance root, and another is the bounce resonance root. The bounce resonance has a stabilizing effect on the RWM.

Parasitic Effect Suppression With Resonance Cancelation for Broadband Absorber/Reflector

This letter exhibits a switchable double-sided absorber/reflector that realizes broadband performance. This structure effectively breaks the limitation of the absorption bandwidth due to the parasitic capacitance of the p-i-n diode through resonance cancelation. First, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> parallel resonance is adapted to inhibit the interference of the parasitic capacitance by connecting the inductance in parallel with the p-i-n diode. Then, a gap capacitance is introduced to increase the resonance frequency and further expand the bandwidth. The double-sided design is applied to avoid the short-circuit phenomenon caused by the parallel connection of the inductor and the p-i-n in the single-sided design. To control the inductance value more precisely, the meander inductor is employed. Finally, the reflectivity of the proposed structure covers broadband of 3.91–9.77 GHz from reflection to below −10 dB under normal incidence by changing the working states. Furthermore, a sample of the proposed structure was manufactured and measured. The measurements are consistent with simulations.

A tailor-made 3-dimensional directional Haar semi-tight framelet for pMRI reconstruction

In this paper, we propose a model for parallel magnetic resonance imaging (pMRI) reconstruction, regularized by a carefully designed tight framelet system, that can lead to reconstructed images with much less artifacts in comparison to those from existing models. Our model is motivated from the observations that each receiver coil in a pMRI system is more sensitive to the specific object nearest to the coil, and all coil images are correlated. To exploit these observations, we first stack all coil images together as a 3-dimensional (3D) data matrix, and then design a 3D directional Haar tight framelet (3DHTF) to represent it. After analyzing sparse information of the coil images provided by the high-pass filters of the 3DHTF, we separate the high-pass filters into effective ones and ineffective ones, and we then devise a 3D directional Haar semi-tight framelet (3DHSTF) from the 3DHTF by replacing its ineffective filters with only one filter. This 3DHSTF is tailor-made for coil images, meanwhile, giving a significant saving in computation comparing to the 3DHTF. With the 3DHSTF, we propose an ℓ 1 -3DHSTF model for pMRI reconstruction. Numerical experiments for MRI phantom and in-vivo data sets are provided to demonstrate the superiority of our ℓ 1 -3DHSTF model in terms of the efficiency of reducing aliasing artifacts in the reconstructed images.

Sample-centred shimming enables independent parallel NMR detection

Two major technical challenges facing parallel nuclear magnetic resonance (NMR) spectroscopy, at the onset, include the need to achieve exceptional B_0 homogeneity, and good inter-detector radiofrequency signal decoupling, and have remained as technical obstacles that limit high throughput compound screening via NMR. In this contribution, we consider a compact detector system, consisting of two NMR ‘unit cell’ resonators that implement parallel B_0 shimming with parallel radiofrequency detection, as a prototype NMR environment, pointing the way towards achieving accelerated NMR analysis. The utility of our approach is established by achieving local field correction within the bore of a 1.05T permanent magnet MRI. Our forerunner platform suppresses signal cross-coupling in the range of -21 dB to -30 dB, under a geometrically decoupled scheme, leading to a halving of the necessary inter-coil separation. In this permanent magnet environment, two decoupled parallel NMR detector sites simultaneously achieve narrow spectral linewidth, overcoming the spatial inhomogeneity of the magnet from 400 to 28 Hz.

A Wideband Frequency-Selective Rasorber With Rectangular Spiral Resonators

This letter presents a frequency selective absorber (FSR) with a passband and two wide absorption bands. The structure is composed of a resistive layer and a bandpass frequency selective surface (FSS) layer. The resistive layer is a combination of metal lines with loaded resistors and rectangular spiral resonators, which generate parallel resonances. Square slots are designed in the bandpass FSS to produce parallel resonance inside the passband and perform as a metal plane outside the passband. A nearly transparent window can be obtained by adjusting the parallel resonant frequencies of two layers to be consistent. The simulation results show that the 3 dB transmission band ranges from 6.5 to 7.76 GHz, and the minimum insertion loss is 0.05 dB at 7.09 GHz. The dual-polarized FSR presents stable operating characteristics and realizes two absorption bands on both sides of the passband, and the fractional bandwidth of the reflection coefficient lower than −10 dB is up to 127%, which ranges from 2.69 to 12.04 GHz. In addition, the FSR is manufactured and measured, and the measurement results are consistent with the simulation results.

Design and Analysis of Multiband Energy Selective Surface Based on Semiconductors

This article presents how to design multiband energy selective surface (ESS), which has a nonlinear transmission response to the power of incidence in multiple frequency band. It is demonstrated that ESSs with an arbitrary number of operating bands could be obtained with both parallel and serial LC resonance circuits and each single operating band could be modulated from a passband with low insertion loss (IL) to a stopband with high shielding effectiveness (SE). Furthermore, a dual-band ESS is designed to verify the proposed methods, in which two rectangular resonance rings mounted with Sckotty diodes are used. A 0.5 IL and 30 dB SE are observed at the central frequency of both operating bands with ECM and full-wave simulations. Prototypes are fabricated and measured with a waveguide set-up. There is a good agreement between the simulations and measurements under low-power incidence. However, some differences are observed under high-power incidence. The reason behind is discussed in detail and some measures for improvement are also proposed. The proposed approach provides general guidelines for multiband ESS design and is supposed to obtain wide use in adaptive shielding for high power microwave (HPM).

A Dual-Resonant Topology-Reconfigurable Inverter for All-Metal Induction Heating

Traditionally, domestic induction heating (IH) is designed to heat the ferromagnetic (FM) pan. However, it is incompetent to heat the non-FM (NFM) pan since the small equivalent resistance of the pan will easily result in overcurrent on the inverter. Inspired by the compensation network in the wireless power transfer (WPT), the series–parallel resonance (SPR) network with a relay switch is newly integrated into the IH technology to develop a dual-resonant topology-reconfigurable inverter for all-metal IH. The proposed system can be purposely configured to a half-bridge series resonant inverter with the pulse width modulation (PWM) to heat the FM pan, or a full-bridge SPR-based inverter with the phase shift control (PSC) to heat the NFM pan, respectively. Moreover, the output–input current gain of the SPR network equals the heating-coil quality factor, thereby readily eliminating the overcurrent issue of the inverter. For exemplification, a 1-kW prototype has been built with system efficiencies of 94.32% and 91.05% for heating FM and NFM pans, respectively. Finally, the proposed system can be evolved to achieve automatic load detection and impedance matching to ensure uninterrupted resonance. Both the calculated and measured results are given to validate the flexibility and feasibility of the proposed system.

Classification of Transmission Modes through a Narrow Slot in a Thick Conducting Screen

This paper examines electromagnetic energy transmission through a narrow slot in a thick conducting plate when a plane wave is incident to the slot. The slot in the thick plate creates a waveguide structure. From the perspective of cutoff frequency, the transmission characteristics are classified into three modes. The transmission cavity resonance (TCR) mode in the range above the cutoff depends on the plate thickness, and peak transmission cross-sections (TCSs) appear periodically along the plate thickness, known as Fabry-Perot resonance. The near-cutoff resonance transmission (NCRT) mode depends on the slot length and plate thickness, and the maximum TCS appears only once as a slot length resonance (or transverse resonance). The peak TCS for the NCRT mode occurs with a thin plate thickness, which produces slot length resonance. The non-transmission cavity (NTC) mode is a non-transmission and non-resonance mode and is not propagated. All the maximum TCSs for the TCR and NCRT modes occur in parallel resonance. The analysis results show that the classification of the three transmission modes through the thick plate slot is effectively explained by the TCS and aperture impedance.

Enhancing Efficiency for Wideband Antennas by Controlling the Parasitic Resonance of the Feed Structure

Parallel resonance feed structures can be used to implement wideband impedance characteristics. However, at some frequencies, parasitic resonance is generated in the feed structure. Radiation efficiency nullification occurs at the frequency of the parasitic resonance. This frequency moves with the size of the feed structure. In this paper, two antennas with different parallel resonance feed structures are presented. By simply modifying the feed structure, the frequency of the parasitic resonance is shifted. The impedance bandwidth and the efficiencies of the two antennas confirm that antenna performance is significantly enhanced when a parasitic resonance is moved away from the antenna operating band. This research provides a simple and feasible method for the design of practical high-performance wideband antennas.

A Comprehensive Review: Topology, Modeling and Control Techniques of Resonant Converter for Electric Vehicle Applications

This paper proposes the comprehensive review on the different resonant converter topologies, different modelling techniques, and different control techniques are being used in electric vehicle application. This paper also discusses the merits and demerits of different modulation/control techniques. The performance of variable frequency control technique can be improvised using SSPM is discussed in this paper. Optimal projectory control method has a quick transient response than SSPSM followed by SSOC, then PSM, and finally by VF controller are reviewed in detail in this study. Cyclic averaging is an accurate alternative method for state variable, this approach is used for time domain analysis of resonant dc-dc converter has been emphasized in this paper. Reverberation would be beneficial when series and parallel resonance converters combined are explained in this paper. LLC topology would be best suitable for electric vehicle applications are discussed and structure of the resonant converters, power efficiency, compatibility and its suitable applications are presented in this paper. A detailed study of modelling techniques to address the increasing demand for electric vehicles are presented.

Empirical Bayesian Inference Using a Support Informed Prior

This paper develops a new empirical Bayesian inference algorithm for solving a linear inverse problem given multiple measurement vectors of noisy observable data. Specifically, by exploiting the joint sparsity across the multiple measurements in the sparse domain of the underlying signal or image, we construct a new support informed prior. Several applications can be modeled using this framework, including synthetic aperture radar observations using nearby azimuth angles and parallel magnetic resonance imaging. Our numerical experiments suggest that using the support informed prior usually improves accuracy of the recovery in the form of the sampled posterior mean and reduces its uncertainty when compared to posteriors constructed using some more standard priors.

A Comparative Study on Applicability of Parallel Resonance Type Fault Current Limiters in Power Systems

A Comparative Study on Applicability of Parallel Resonance Type Fault Current Limiters in Power Systems

Additively manufactured dual-functional metamaterials with customisable mechanical and sound-absorbing properties

ABSTRACT Acoustic metamaterials with broadband sound-absorbing capacity open up applications in aerospace, automotive, marine, defense, etc. For such applications, sound-absorbing materials that can withstand complex loading conditions are essential. Hence, to address acoustic and mechanical requirements simultaneously, we propose plate-reinforced dual-functional micro-lattice metamaterials (PDMMs) that exhibit elastic isotropy, dual crushing stages with a specific energy absorption up to 25.82 kJ/kg, and ultra-broadband sound absorption from 0.97 kHz to 6.30 kHz. The remarkable elastic isotropy lies in the topology-induced structural stiffness homogenising effect. The transition from single to dual plateau anti-compression stages is controlled by tailoring the structural local strength. On-demand broadband sound absorption is achieved by modulating the parallel coupling and cascade resonance effects, and the physical mechanism is revealed by examining impedance matching and system damping states. Overall, the presented novel metamaterials exhibit exceptional application potentials by overcoming the trade-offs usually found in traditional mechanical and acoustic metamaterials.

Harmonic Performance Analysis of Static Var Compensator Connected to the Power Transmission Network

The static var compensator (SVC) is a device which is designed to compensate reactive power, increase voltage stability and to reduce voltage fluctuations. Thyristor controlled reactors (TCRs) are composed of reactors in series with bidirectional pair of thyristors. Current through reactors can be continuously controlled by changing the firing angle of thyristor valves, thus&#x0D; the inductive power can be easily controlled. Typical applications of TCRs in AC systems are voltage stabilization and temporary overvoltage reduction, stability improvement, damping of power oscillations and load balancing. In this paper, harmonic performance analysis of SVC equipped with TCRs is presented. SVCs utilizing TCRs generate harmonic currents and therefore it is necessary to determine the effect of harmonics generated by the SVC on the power system and its elements. This includes interaction of the SVC with the system, the SVC performance under balanced and unbalanced operating conditions and finally, evaluation of countermeasures such as installation of harmonic filters. In order to carry out these analysis, it is necessary to determine harmonic characteristics of the network at the point of SVC connection, existing levels of harmonics, and to know appropriate standards regarding acceptable harmonic levels in the power system. Since harmonic distortions in the system are caused by the interaction between SVC and the system, all system contingencies which may affect system’s frequency response should be evaluated. Detailed power system model should be considered to make sure that parallel resonance points of system do not directly coincide with characteristic harmonics from the SVC. Harmonics generated by SVCs are largely dependent on the operating point within the SVC characteristic. A conservative approach is to use the maximum values of harmonics generated within the spectrum irrespective of the operating point. The results of harmonic performance analysis are important for appropriate design of SVC. Harmonic performance analysis related to SVC application which are presented in this paper include the determination of: frequency response of the transmission network impedance required for the specification and design of filters; the effects of SVC generated harmonics on the power system; the overall filter requirements and countermeasures to reduce harmonics to acceptable levels.

Enhanced plasma generation in capacitively coupled plasma using a parallel inductor

Plasma generation efficiency in a capacitively coupled plasma (CCP) at high densities or high conductivity tends to be lower due to low plasma resistance. An inductor is installed to a powered electrode in parallel to improve plasma generation efficiency at higher density in the CCP. To reduce the power loss in a system, a parallel resonance is used between the capacitance of the CCP and the inductance of the parallel inductor. When parallel resonance occurs, the impedance of the chamber, including the plasma, increases. Therefore, the current flowing in the system is expected to decrease. At the resonance, the current in the system significantly decreases, and the voltages and currents at the powered electrode significantly increase. This phenomenon indicates that the system power loss is decreased, and the power absorbed by the plasma is increased. As a result, the ion density and the voltage at the powered electrode are increased up to 66% and 25% at the parallel resonance condition, respectively. To understand these increases, a circuit model for the plasma and the parallel inductor is suggested which shows good agreement with the experimental results. This method can be applied to the CCP for improving plasma generation.

Dual-Band Bandstop Filtering Cable Design Using Defected Conductor Layer With Asymmetric Spiral Structure

In this article, we present a novel dual-band bandstop filtering cable by surrounding inner wire with asymmetric bridge-connected spiral-shaped defected structure on outer conductor. The simulation results demonstrate that the proposed dual-band bandstop filtering cable can be modeled by two parallel RLC resonance circuits in cascade and the performance can be easily adjusted by changing the structural parameters. The well-designed dual-band bandstop filtering cable can be fabricated by core wire surrounding with polytetrafluoroethylene (PTFE) dielectric layer and polyimide defected conductor layer with asymmetric bridge-connected spiral-shaped defected structures. The proposed filtering cable with ten asymmetric bridge-connected spiral-shaped defected resonators on defected conductor layer has a compact size of diameter 1.66 mm and length 200 mm, and its insertion loss in experimental results is greater than 20 dB at 0.88 and 1.3 GHz. Compared with the traditional microstrip bandstop filter, the proposed dual-band bandstop filtering cable can achieve better stopband and passband performance within more compact size. In essence, it is a cable replacement technology, which can improve electromagnetic compatibility (EMC) performance at system level and equipment level, and has the potential to be widely used in wireless system.