Resonant Capacitor Research Articles

Design of a hybrid frequency selective rasorber with wide band absorption performance for C, X, and K bands

AbstractHybrid frequency selective rasorber (FSRs) composed of hybrid lossy layers and bandpass frequency selective surfaces (FSSs) are proposed in this study, which works as an absorber with absorption bands of 3.34–11.95 GHz and 17.44–24.29 GHz providing the fractional bandwidths of 112% and 33% while reserving a transparent window from 13.75 to 15.32 GHz. The proposed FSR is designed by stacking a hybrid lossy layer and band‐pass FSS. One of the lossy layers is composed of a λ/4 transmission line resonator in the middle of the lumped resistors' loaded bent dipole, which realizes an absorption‐transmission (A–T) frequency response, and the other is constructed by four stripe‐type parallel inductor and capacitor resonators connected to a lumped resistors' loaded circular ring, which realizes T–A frequency response. The bandpass FSS is a three‐tier structure in which the top and the bottom layers are composed of periodical circle patches and the middle layer is composed of circle slots. To explicate the working mechanism of the hybrid FSR, an equivalent circuit model is established, meanwhile, the surface current loss is analyzed. A fabricated prototype of the proposed FSR is assembled and measured to test the simulated frequency response.

Electrostatic nonlinear dispersive parametric mode interaction

Understanding and controlling the nonlinear coupling in micro/nanomechanical resonators are of great importance to the exploitation of advanced devices. The recently observed electrostatic nonlinear parametric coupling is a very interesting topic. However, the theoretical model of the electrostatic parametric coupling remains unclear. This paper explicitly derives the model and the electrostatically induced dispersive parametric coupling which reveals the ability to tune the bifurcation topology of capacitive resonators is analyzed based on the multiple-time-scale method. A novel displacement-to-frequency transduction scheme based on this electrostatic dispersive parametric coupling effect is proposed. The transduction sensitivity is theoretically given, which indicates that this electrostatic dispersive transduction scheme can provide even more design freedoms than the existing displacement-to-frequency transduction scheme based on tension modulation. In addition, a bifurcation reversal effect is predicted in the strong actuated states of the dispersive parametric coupled system, which reveals the ability to tune the bifurcation topology of capacitive resonators.

Inductive Power Transfer Battery Charger with IR-Based Closed-Loop Control

A wireless battery charger with inductive power transfer (IPT) was proposed in this paper. The commonly used constant-current constant-voltage (CC-CV) charging method is accomplished by a closed-loop controlled IPT with a hybrid resonant circuit on the secondary side. A smooth transition between the CC stage and the CV stage can be made simply by swapping exactly the associated switches on resonant capacitors. The required charging voltage and current are regulated by controlling the phase-shifted angle of the high-frequency inverter on the primary side. To stabilize the charging current and voltage, a closed-loop digital controller was introduced with infrared (IR) transmission feedback. Precise regulation of the resonant inverter on a relative small ranged phase-shifted angle can be realized by two 16-bit microcontroller units (MCUs) with compact encoding and decoding techniques. A hybrid resonant inverter was designed for a 600 W prototype of the proposed IPT battery charger. Experimental results from exemplar cases have demonstrated that the battery charger can provide a stable charging current at the CC stage and then transit smoothly into the CV stage.

Minimizing Leakage Magnetic Field of Wireless Power Transfer Systems Using Phase Difference Control

In this paper, we propose a method to reduce the leakage magnetic field from wireless power transfer (WPT) systems with series–series compensation topology by adjusting the phase difference between the transmitter (TX) coil current and the receiver (RX) coil current without additional shielding coils or materials. A WPT system employing the proposed method adjusts the phase difference between the TX coil current and RX coil current by tuning a resonant capacitor of the RX coil. The conditions for minimizing the leakage magnetic field are derived, and the range of the resonant capacitor of RX, considering power transfer efficiency and the leakage magnetic field, is proposed. Through simulations and experiments, it is verified that the proposed method can reduce the leakage magnetic field level without any additional materials. For that reason, the proposed method can be suitable for size-limited, weight-limited or cost-limited WPT systems.

Domestic Induction Heating System With Standard Primary Inductor for Reduced-Size and High Distance Cookware

In this article, a hybrid wireless power transfer system, which combines induction heating (IH) and inductive power transfer functionalities, is proposed to improve the performance of a domestic IH application with small loads weakly coupled to distant inductors. Considering the basic single-inductor domestic IH application, the proposed system adds a secondary inductor with a series compensation capacitor directly attached to the small ferromagnetic cookware. The extended distance can be used to implement the glassless induction concept, where the ceramic glass of typical cooktops is substituted by the kitchen surface itself. The design of the secondary coil is carried out by means of a combination of finite-element and electrical simulations. A design process, including the housing of the resonant capacitors and the selection of the secondary winding number of turns and cabling, is presented. As a result, a prototype is implemented and tested under working conditions up to 1500 W at several distances. Experimental results validate the electrical modeling and simulation. Moreover, thermal results confirm the feasibility of the proposal and validate the adopted strategies for the capacitor housing.

Design of a novel compact highly selective wideband bandstop RF filter using dual path lossy resonator for next generation applications.

This article presents the design of a wideband bandstop RF filter intending to improve selectivity and compactness. Conventional bandstop filter topology with finite unloaded quality factor produces degraded bandstop filter performance due to dissipation loss. In the proposed filter design, a novel dual path Capacitive Coupled Step Impedance Resonator (CCSIR) structure is used to obtain an infinite stopband attenuation. A uniform impedance resonator is used in Path 1, whereas Path 2 contains a resonator that is twice coupled to the transmission lines. The electrical length of both paths is chosen to be out of phase, resulting in a high rejection level at higher frequencies. It has been analyzed that the selectivity can be improved by increasing the order of the dual coupled step impedance resonator. The proposed design produces a wideband BSF centered at 5.25 GHz with a high rejection level of 104.3 dB and fractional bandwidth of 58.5%. The results have demonstrated that the resonant frequencies are regulated by varying the electrical length of CCSIR. Moreover, it has been realized that out of phase signal cancellation due to the dual path is involved in producing the finite frequency transmission poles, which further enhances the filter selectivity. However, the same electrical performance can only be achieved from coaxial cavities and waveguides due to the high-quality factor. The proposed topology is fabricated and measured on a high-frequency microstrip substrate having a low-quality factor with a compact output and better electrical performance compared to coaxial cavities or waveguides. Due to its high electrical performance and small size, the proposed BSF is appropriate for 4G and 5G (FR1) applications. The measurement shows good concurrence with the full-wave EM simulated results. The fabricated prototype of third order BSF has a compact size of (0.7 × 0.77)λg at 5.25 GHz.

Application of Convolutional and Feedforward Neural Networks for Fault Detection in Particle Accelerator Power Systems

High voltage converter modulators (HVCM) provide power to the accelerating cavities of the Spallation Neutron Source (SNS) facility. HVCMs experience catastrophic failures, which increase the downtime of the SNS and reduce beam time. The faults may occur due to different reasons including failures of the resonant capacitor, core saturation due to the magnetic flux, insulated-gate bipolar transistor (IGBT) failures, and others. We recently have setup a HVCM test stand to develop and test machine learning models for anomaly detection and fault prognostics. In this work, we propose binary classifiers and autoencoder architectures based on convolutional (CNN) and feedforward neural networks (FNN) to facilitate distinguishing normal from faulty waveforms coming from the HVCM during operation. The results indicate that the CNN binary classifier is the best model among the four showing very stable performance in the training and testing sets with impressive precision and recall metrics, reaching up to 99% with a very small uncertainty. The FNN classifier shows the least performance with a large uncertainty in its metrics. The performances of the two autoencoders based on CNN and FNN were in between, showing very good performance nonetheless.

A Unified Common Inductor and Common Capacitor Current Sharing Method for Multiphase LLC Converter

The common inductor and common capacitor current sharing technologies with excellent current sharing capabilities and low-cost have attracted a lot of attention in recent years. However, these methods have certain limitations. To solve this problem, this paper proposes a unified common inductor common capacitor scheme. Firstly, the existing common inductor and common capacitor methods are reviewed. Based on the first harmonic approximation (FHA) analysis method, the limitations of these schemes are analyzed, and we find that the current sharing performance is not well when the multi-resonant parameters are mismatched, which will cause the one-phase to bear more power, even over-powered and damaged. To realize a better current sharing of multi-phase LLC modules, a unified common inductor common capacitor method is proposed in this article, where the series resonant inductors and resonant capacitors in each LLC converter are connected in parallel. The current sharing performance of the proposed method is analyzed by the FHA analysis method, and the proof-of-concept prototype with a 480W 24V two-phase LLC converter was built to verify the effectiveness of the proposed method. Simulation and experimental results show that the current sharing error of the proposed method is 2.1% under half load and 0.9% under full load.

Parameter Identification Method With Dynamic Impedance Modulation for the DWPT System

A novel parameter identification method with dynamic impedance regulation is proposed to maintain constant output voltage of dynamic wireless power transfer (DWPT) system under varied loads and mutual inductance conditions. The resonant capacitor in the receiver side is replaced with a switched-controlled capacitor (SCC) structure, which enables the system to work under two operation modes. And then a comprehensive mathematical model is established according to these two modes to achieve the parameter identification. To avoid the deterioration of identification accuracy caused by the capacitors’ parameter drift, a dynamic impedance regulation method is introduced. The SCC is under dynamic closed-loop modulation to realize precious control of the equivalent capacitance of resonant capacitor in the receiver side. An experimental prototype is built in the laboratory, and the experimental results clearly demonstrate the accuracy of the proposed parameter identification.

Improved Dynamic Behavior for the Series-Resonant Converter Using Bidirectional Charge Control

A new control method for the bidirectional series-resonant converter is presented that optimizes dynamic behaviour. The series-resonant converter is a frequently used converter type due to its inherent zero-voltage switching property for switching frequencies above the resonance frequency. However, a method to control the series-resonant converter dynamically while facilitating bidirectional power flow and zero-voltage switching of all switches is not yet presented. This paper presents bidirectional charge control, a control method that realizes dynamic, bidirectional operation of the series-resonant converter. It targets a net amount of charge displacement through the controlled port between two consecutive zero-current crossings, by describing all switching events as a function of the charge difference across the resonant capacitor. As a result, bidirectional charge control facilitates ZVS operation of all switches, regardless of the operating conditions, while minimizing the \textcolor{blue}{reactive currents through the connected voltage sources}. This paper describes both the theoretical analysis regarding bidirectional charge control as well as an experimental verification including non-idealities and the corresponding implementation to guarantee the desired control of the series-resonant converter. Bidirectional charge control realizes dynamic, bidirectional operation of the series-resonant converter while guaranteeing zero-voltage switching of all switches.

Wireless and Battery-Free Biosensor Based on Parallel Resonators for Monitoring a Wide Range of Biosignals

This paper proposes a novel wireless, battery-free, and label-free biosensor for minimally invasive and non-invasive permittivity sensing for applications such as detecting glucose levels in the interstitial dermal fluid. The miniaturized, fully passive sensor is based on two symmetric parallel 0.8 mm$^3$ LC (inductor-capacitor) resonators. Each inductor is integrated with a conductive plate at one of its terminals. The passive sensor's main field is dominant outside the resonators, creating an effective capacitance outside the sensor, unlike reported in previous studies where the effective capacitance was limited to between the resonator lines. The proposed sensor was further analyzed under two different scenarios to change the region of effective capacitance and test its suitability for pressure monitoring, such as wound monitoring; first, by repositioning one of the two resonators, and second, by replacing one of the resonators with a conductive plate. The experimental results confirmed the proposed passive sensor's performance in detecting the glucose concentration in an aqueous solution with a sensitivity of 500 and 46 kHz/(mg/dL) for minimal invasive and non-invasive monitoring, respectively, within the glucose range of 0-500 mg/dL with volume sample requirements as low as 60 $\mu$L. Further, by repositioning one of the resonators, the effective capacitance lies inside the passive sensor, making it suitable for wound monitoring. The results indicated that the resonance shift can be made fairly linear with respect to the variation in the separation between the resonators with a sensitivity of 2.5$\times 10^3$ MHz/mm within the separation range of 0.2-0.5 mm, considering separation as the main factor to sense the pressure or healing of the wound.

Dispersive Resonance Modulation Based on the Mode-Coupling Effect in a Capacitive Micromechanical Resonator

This paper presents a theoretical and experimental investigation into the electrostatic coupling mechanism between different nonlinear modes inside a single resonator. Nonlinear intermodal coupling allows an arbitrary mode to be used as a modulator for the resonance of the coupled mode, presenting an efficient method to tune the frequency of a specific vibration mode. Here, a capacitive micromechanical resonator is developed, in which different modes exhibit different nonlinear characteristics. Inside this resonator, interactions between different nonlinear modes induced by electrostatic fields are observed and accurately modeled. It demonstrates that resonance modulation control can be achieved by activating the coupled modes based on the dispersive parametric coupling effect. Meanwhile, the resonance modulation is jointly determined by coupled modes, providing a theoretical basis and approach for modal manipulation technology. The dispersive coupling between intrinsic modes enables the probe resonance to be tuned by nearly 100 times its bandwidth, and its range and polarity can also be controlled by selecting the resonance of the pump mode. It is proven that resonance modulation control induced by the modal coupling effect can efficiently tune the resonator's resonance frequency over a wide range, which presents a promising voltage-frequency transduction scheme with high sensitivity and low noise for the precision instrument. Its pull range exhibits a great potential of more than 20% as a voltage-controlled oscillator and can be customized to satisfy different requirements, paving the way toward advanced mechanics.

Averaged large-signal model of a DC-DC isolated forward resonant reset converter for a solar cell battery charger using internet of things: implementation

In this study, an analysis and modeling circuit for controlling battery charge solar cells based on data management through internet of things (IoT) is presented. For this proposed, a DC-DC forward resonant reset converter is employed and can be charged at a constant current and constant voltage. Data management of various parameters using IoT technology is provided, via which notifications can be sent to an external application. The proposed converter can give an output voltage of 14.4 VDC for a voltage range including between 9 and 18 VDC, using an isolated transformer and a halfwave rectifier circuit. The main switch of the forward resonant reset converter can operate under a zero-turn-on condition. This approach has the benefit of utilizing a leaking inductance. Llkp and resonant capacitor Cr to reset the remaining flux saturation on the high-frequency transformer. A simulation model prototype was created and tested at a set switching frequency of 50 kHz, 14.4 VDC constant output voltage, and output power of approximately 29 W. An efficiency of 96% at maximum full load can be reached. The proposed analysis techniques and mathematical model were verified via simulation and experimental results, and the obtained results are in agreement with the theoretical analysis.

A Real-Time Calibrated Adaptive-ZVS Class-D Power Amplifier for 6.78 MHz Wireless Power Transfer System

This brief presents a class-D power amplifier (PA) with an adaptive zero-voltage switching (A-ZVS) technique for 6.78 MHz resonant wireless power transfer (R-WPT) system. In R-WPT operation, the loading impedance of a PA can be varied by the process tolerance of the LC resonant components or WPT environments, such as the resonant topology, coupling coefficient, and loading condition of the receiver. In particular, the commonly used series-parallel resonant topology suffers from resonant point deviation of primary LC tank, resulting in hard switching of the PA. Consequently, efficiency degradation and electromagnetic interference can occur under multi-MHz operation. The proposed A-ZVS feedback loop calibrates the equivalent resonant capacitance in real-time to achieve ZVS by adjusting the loading impedance to be slightly inductive. The proposed PA was fully integrated except for one switched capacitor used as the tuning element and fabricated in a TSMC 0.18 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> BCD process. The measurement results demonstrated robust ZVS operation with a peak system efficiency of 52.7 % and an enhanced maximum transmitting power of 107 %.

Accurate Steady-State Modeling and Design Based on State Trajectory Analysis for LCC Resonant Converter With Voltage Doubler Rectifier

The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> series–parallel resonant converter with a voltage doubler rectifier, widely used in X-ray machines, is required to meet an extremely wide output range. However, state-of-the-art models are based on fundamental harmonic approximation and cannot maintain good accuracy over the entire output range. The state trajectory method has the potential to achieve a full range of high accuracy without high complexity, but it only applies to simple topologies, like <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> with a full-bridge rectifier. For <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> with a voltage multiplier, the capacitors in the multiplier are involved in the resonance, which can be modeled as a five-element resonant circuit. Moreover, the conduction sequence of components in the minor mode is different from that in the major mode, which is usually ignored in the steady-state model. The influence of the output capacitance of power transistors on the state trajectory is so unclear that the model accuracy decreases considerably at high frequencies. In this article, the equivalent parallel resonant capacitance is derived through the current distribution. The steady-state model of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> converter with a voltage doubler rectifier is developed for both major mode and minor mode. The deviation of the state trajectory and modeling accuracy induced by the output capacitor is investigated. Based on the proposed model and device stress analysis, the design procedure for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> under a wide operation range is presented. The simulations and experiments verify the accuracy of the model and the validity of the design method. The simulation mismatches are less than 2.3% over the entire output range. The maximum experimental mismatch is 15%.

Research on auxiliary resonant commutated pole inverter for driving brushless DC motor

The brushless DC motor is generally used in small satellite flywheel systems due to its good control performance and structure robustness. However, its driving inverter still suffers from hard-switching that leads to higher loss and larger heatsink requirement. The resulting low power density and EMI problems have been a great challenge for the space satellite applications. This paper describes a novel auxiliary resonant commutated pole inverter (ARCPI) for driving the brushless DC motor. An inserted inductor is controlled to resonant with the buffer capacitor of the inverter’s lower arm switches; a resonant capacitor is paralleled with the inductor branch as well. Zero-current switching and zero-voltage switching conditions are therefore realized for the switches of the entire circuit. The reverse recovery problem of diodes are also avoided by zero current turning-off. The working states of the proposed novel ARCPI inverter are analyzed and the mathematical model for every state is established. Furthermore, the parameter design is discussed to provide soft-switching conditions. Finally, the proposed ARCPI inverter is applied for driving a brushless DC motor. A voltage/current double closed control loop is designed for the motor controller and the system simulation setup is built. The simulation results prove that soft-switching operation is realized for all of the switches; the proposed inverter is effective for driving brushless DC motors. Besides, the motor current fluctuation decreases by 45.7%. The motor torque and the motor speed present with good control performance as well.

Fully integrated topological electronics

Topological insulators (TIs) have attracted significant attention in photonics and acoustics due to their unique physical properties and promising applications. Electronics has recently emerged as an exciting arena to study various topological phenomena because of its advantages in building complex topological structures. Here, we explore TIs on an integrated circuit (IC) platform with a standard complementary metal-oxide-semiconductor technology. Based on the Su–Schrieffer–Heeger model, we design a fully integrated topological circuit chain using multiple capacitively-coupled inductor–capacitor resonators. We perform comprehensive post-layout simulations on its physical layout to observe and evaluate the salient topological features. Our results demonstrate the existence of the topological edge state and the remarkable robustness of the edge state against various defects. Our work shows the feasibility and promise of studying TIs with IC technology, paving the way for future explorations of large-scale topological electronics on the scalable IC platform.

Piezoelectric Lateral-Extensional Mode Resonators With Reconfigurable Electrode and Resonance Mode-Switching Behavior Enabled by a VO₂ Thin-Film.

This article presents the first two-port lateral-extensional mode zinc oxide (ZnO) piezoelectric resonator with a reconfigurable bottom electrode that is enabled by embedding a vanadium dioxide (VO2) thin film. The insulator-to-metal phase transition of VO2 is triggered by substrate heating that translates to abrupt changes in electric field patterns and piezoelectrically transduced modal vibrations, thus allowing mode-switching of piezoelectric resonators at specific frequencies. Finite element method (FEM) analysis was used to model the broadband frequency response, while frequency characteristics of the corresponding two-port resonator were measured over a temperature range between 20 °C and 95 °C with a specific focus on two resonances at 88 and 148 MHz. By leveraging the hysteretic behavior of VO2 thin film during a heating/cooling cycle, a change in both the capacitive feedthrough and resonance signal levels was observed, due to the abrupt change in the conductivity of VO2 during its phase transition. The unique switch- ON behavior of the resonance at 88 MHz starts at 70 °C during the heating cycle, while the switch- OFF transition begins at 60 °C during the cooling cycle. On the other hand, when the temperature is increased from 20 °C to 60 °C, a decrease in the insertion loss and resonance frequency of 12 dB and 0.28 MHz, respectively, were observed for the resonance at 148 MHz. Meanwhile, a resonance frequency increase of 0.42 MHz was observed during a temperature increase from 60 °C to 95 °C, which can be ascribed to VO2 phase transition from monoclinic to rutile phase. The hysteresis loops for insertion loss and resonance frequency indicate a different critical temperature for phase transition from the monoclinic (insulator) phase and rutile (metallic) phase and vice versa. The substantial variation in the temperature coefficient of frequency can be largely ascribed to electrode reconfiguration enabled by VO2 phase transition.

Efficiency improvement of a three-coil WPT system with rectified load based on a selected compensation capacitor

ABSTRACT In the existing pieces of literature about the three-coil wireless power transfer (WPT) system, a three-coil structure is proposed to increase the efficiency compared to the two-coil WPT system. The cross-coupling among three coils, compensation capacitor of the repeating coil (RPC) and the rectified load are considered incompletely. The circuit model of a three-coil WPT system with rectified load is developed by taking the cross-coupling of all coils and the compensation capacitor of RPC into consideration in this paper. The relationship among system efficiency, compensation level, and rectifier load is deduced. The detailed mathematical analysis and compensation capacitor selection of RPC are investigated to improve the system efficiency. An experimental study demonstrates that the selected compensation capacitor of RPC achieves a higher efficiency than resonant compensation in a three-coil WPT system with different cross-coupling conditions and rectifier load conditions. System efficiency is promoted from 73.9% (resonant compensation capacitor for RPC) to 84.2% (selected compensation capacitor for RPC).

A Bidirectional DHC-LT Resonant DC-DC Converter with Research on Improved Fundamental Harmonic Analysis Considering Phase Angle of Load Impedance

This paper presents a novel 400 V–50 V bidirectional DHC-LT resonant DC-DC converter. By adding a resonant capacitor and an auxiliary transformer based on LLC, zero-voltage switching (ZVS) and zero-current switching (ZCS) are achieved, while the output voltage gain range is broadened in two directions. Operation principles and robustness are discussed with equations. Then, the error factor of fundamental harmonic analysis (FHA) in resonant converters is analyzed. Considering the phase difference between the output voltage and resonant tank current, an improved method is proposed to describe the behavior of the DHC-LT converter more precisely. A comparison is conducted to prove the effectiveness of the proposed FHA. Furthermore, in order to reduce the output voltage and provide a ripple-free charging current, a fixed-frequency phase-shift strategy is introduced in the DHC-LT converter. ZVS can be realized through the reasonable design of dead time and phase-shift angle. Finally, a 2.5 kW prototype of the DHC-LT resonant DC-DC converter with a digital signal processor (DSP) platform and a battery/PV DC test system is established in the lab to validate the theoretical analysis.