Showing papers on "RLC circuit published in 2021"

Response regimes of nonlinear energy harvesters with a resistor-inductor resonant circuit by complexification-averaging method

Abstract: In this paper, the steady-state response regimes of nonlinear energy harvesters with a resistor-inductor resonant circuit are theoretically investigated. The complexification averaging (CA) method is used to theoretically analyze the energy harvesting performance and reduce the motion equations into a set of first-order differential equations. The amplitudes and phases of both the response displacement and the output voltage are derived, and the corresponding stability conditions are determined. The response regimes are studied with the variation of nonlinear stiffness coefficients and coupling parameters, which are verified by the time domain analysis. The frequency island phenomenon is found and analyzed. Additionally, the backbone curve for deducing the extreme vibration frequency and amplitude is derived. Simultaneously, the analytical expressions of the switching points (critical amplitude and frequency) to identify the hardening and softening properties are established. Accordingly, a criterion is given to determine the occurrence of the jump phenomenon, and its effectiveness is verified. Overall, this paper presents an in-depth theoretical analysis of nonlinear energy harvesters with a resistor-inductor resonant circuit. It presents the theoretical framework and guidance for more extensive evaluations and understanding the theoretical analysis of nonlinear energy harvesters with external circuits.

An Ultraefficient DC Hybrid Circuit Breaker Architecture Based on Transient Commutation Current Injection

Abstract: Protection against circuit faults represents a major technical challenge in the emerging dc transmission and distribution power networks. A popular prior-art dc hybrid circuit breaker (HCB) using a series load commutation switch (LCS) offers an excellent solution with arcless operation but suffers from a high conduction power loss associated with the LCS. This article proposes a new HCB architecture that relies on a switching-mode transient commutation current injector (TCCI) circuit instead of the LCS. The TCCI in the electronic path remains in a standby mode with near-zero power loss under normal conditions, but can rapidly generate a pulse current matching the fault current, and therefore facilitate current commutation from the mechanical to the electronic path. It completely eliminates the conduction power loss associated with the LCS, and delivers ultrahigh transmission efficiency. The TCCI circuit provides a near-zero voltage and a small high-frequency ac ripple current condition for the mechanical contacts to separate arclessly. A 600-V/20-A HCB prototype based on a two-phase current source buck converter topology and a high-voltage vacuum relay has experimentally validated the HCB concept, and demonstrated a mechanical to electronic commutation time of $7.2~\mu \text{s}$ , a total active response time of $310~\mu \text{s}$ , and a peak interrupted fault current of 89 A at a dc bus voltage of 400 V. The new HCB architecture can be applicable in medium voltage direct current (MVDC) (>5 kV) and high voltage direct current (HVDC) (>100 kV) applications as well.

Differentiation and Passivity for Control of Brayton–Moser Systems

Abstract: This article deals with a class of resistive–inductive–capacitive (RLC) circuits and switched RLC (s–RLC) circuits modeled in the Brayton–Moser framework. For this class of systems, new passivity properties using a Krasovskii-type Lyapunov function as storage function are presented, where the supply rate is function of the system states, inputs, and their first time derivatives. Moreover, after showing the integrability property of the port-variables, two simple control methodologies called output shaping and input shaping are proposed for regulating the voltage in RLC and s–RLC circuits. Global asymptotic stability is theoretically proved for both the proposed control methodologies. Moreover, robustness with respect to load uncertainty is ensured by the input shaping methodology. The applicability of the proposed methodologies is illustrated by designing voltage controllers for dc–dc converters and dc networks.

Efficient Estimation and Characteristic Analysis of Short-Circuit Currents for MMC-MTDC Grids

Abstract: Short-circuit current calculation and its characteristic analysis are the foundation of selecting circuit breakers and designing protection systems. First, a companion circuit-based method is presented to fast calculate the short-circuit current of asymmetric bipolar modular multilevel converter-based multiterminal direct current (MMC-MTDC) grids. With the reduction of the whole MTDC grid into an equivalent RLC circuit, the short-circuit current of the grid is efficiently and accurately solved by companion circuit method instead of the numerical integration. In addition to the efficiency, the proposed method can readily adapt to various types of MTDC grids and all kinds of dc faults. Second, unique short-circuit current characteristics of a bipolar MTDC grid following different types of dc faults are theoretically analyzed. A fault type discrimination method is then proposed for bipolar MMC-MTDC grids with dedicated metallic return. Finally, intensive numerical results of two MTDC grids validate the accuracy, adaptability, and efficiency of the presented dc grid short-circuit current calculation method as well as the correctness of the short-circuit current characteristic analyses.

Ultra-Wideband Rectenna Using Complementary Resonant Structure for Microwave Power Transmission and Energy Harvesting

Abstract: An ultra-wideband (UWB) rectenna (fractional bandwidth >100%) using a novel wideband complementary matching stub is proposed for microwave power transmission and energy harvesting A simple resonant structure, ie, LC series–parallel resonant circuit, is embedded to the L-shaped complementary matching stub Due to the unique frequency response of the LC resonant circuit, the proposed matching stub can exhibit “open” and “short” circuits as a function of frequency, thereby acting as a complementary matching circuit covering a relatively wide frequency range Having utilized the proposed matching stub, the nonlinear input impedance of the rectifier can be tuned to conjugately match the antenna impedance throughout the frequency band of interest Simulated and measured results show that the proposed rectenna has good matching performance ( $S_{11} dB) and high RF-dc conversion efficiency (>50%) over a relatively wide frequency range from 09 to 3 GHz (for GSM, Wi-Fi, and WLAN bands) The maximum conversion efficiency of 734% is realized at 3-dBm input power It is evident that the proposed resonant structure-based matching scheme is a promising and effective solution to facilitate the UWB rectenna design with stably high efficiency over a very wide frequency band

Zero-Voltage-Switching Current Source Inverter Fed PMSM Drives With Reduced EMI

Abstract: The silicon carbide (SiC) devices have attracted more and more attention due to the capability of withstanding higher blocking voltage, higher switching frequency, and higher temperature However, challenges for SiC devices applied in voltage-source-inverter fed motor drives such as electromagnetic interference (EMI) issues and limited over-current capability still limit the further application of SiC devices In this article, a novel SiC devices based zero-voltage-switching (ZVS) current-source-inverter (CSI) is proposed for permanent-magnet synchronous motor (PMSM) drive The key is to propose an auxiliary resonant circuit, which achieves ZVS conditions for all switches in power circuits and reduces the dv/dt of high speed SiC devices The resonant capacitor in the auxiliary circuit can clamp overvoltage caused by possible open-circuit faults To further reduce the EMI, the random switching frequency pulsewidth modulation is designed for the proposed CSI motor drive The system configuration, working principle, circuit design, and control schemes are described in detail Both simulations and experiments are presented to verify the effectiveness of the proposed ZVS-CSI fed PMSM drive system

Bidirectional DC–DC Wireless Power Transfer Based on LCC-C Resonant Compensation

Abstract: A bidirectional dc–dc wireless power transfer (WPT) based on LCC-C resonance compensation is proposed in this article. For the power flowing from the primary side to the secondary side (P2S), the voltage source is converted to a current source (V–C) on the primary side and the current source is converted to a voltage source (C–V) on the secondary side. For the power flowing from the secondary side to the primary side (S2P), the V–C conversion occurs on the secondary side and the C–V conversion occurs on the primary side. The proposed bidirectional dc–dc WPT using LCC-C resonance compensation exhibits several advantages: 1) it operates in bidirectional power flow; 2) it prevents burn out of the coil when there is an open circuit on the load side or the coils are misaligned; and 3) it outputs a constant current (CC) or a constant voltage (CV). A hardware prototype is designed using the specification SAE-J2954, the operating frequency is 85 kHz, the maximum output power is 3.7 kW and the vertical distance for the coil gap is 15 cm. The experimental results verify that the proposed bidirectional dc–dc WPT performs as expected.

An Optimized Digital Synchronous Rectification Scheme Based on Time-Domain Model of Resonant CLLC Circuit

Abstract: Uncontrolled rectification on the secondary side of the resonant CLLC circuit causes a large amount of conduction loss. Accurate synchronous rectification (SR) can reduce conduction loss by replacing rectifier diodes with mosfets’ channels exactly. The accuracy of the SR signals depends on the determination of the zero-crossing points of the secondary side resonant current. In this article, an accurate time-domain model is introduced for the resonant CLLC circuit to obtain these zero-crossing points. This modeling method is more accurate than first harmonic approximation and requires less computational effort than extended harmonics approximation. Compared with previous time-domain modeling methods, the proposed time-domain model gives detailed circuit state expressions and covers the entire circuit operating states. Relying on the accurate circuit model, the SR scheme proposed in this article can adaptively generate SR signals in different frequency ranges and has the ability to switch modes smoothly. And this method can be used for the later efficiency optimization of CLLC converters that do not originally have SR function, only through the control program update. Moreover, the robustness of the proposed SR method is analyzed, and the proposed concept is verified through a 3-kW resonant CLLC prototype.

Resonance Effect Reduction With Bandpass Negative Group Delay Fully Passive Function

Abstract: This brief introduces an original reduction method of resonance effect dispersion by using bandpass negative group delay (NGD) function. The dispersion transfer function (TF) is model by lumped RLC circuit. The canonical parameters of NGD passive cell are innovatively formulated as a function of the resonance dispersion specifications. The developed method feasibility is validated with commercial tool frequency domain simulations. Proofs-of-concept constituted by passive RLC-resonant and NGD fully passive circuits are considered. The results confirm an obvious peak reduction of resonance magnitudes and GDs from (15-dB, 20-ns) to better than (11.5-dB, 8.6-ns) are realized in the NGD bandwidth of about 20 MHz. The NGD method robustness is also investigated with simultaneous and individual relative variations of the dispersion parameters.

Optimized Resonators for Piezoelectric Power Conversion

Abstract: The performance of inductors at high frequencies and small sizes is one of the largest limiting factors in the continued miniaturization of dc-dc converters. Piezoelectric resonators can have a very high quality factor and provide an inductive impedance between their series and parallel resonant frequencies, making them a promising technology for further miniaturizing dc-dc converters. In this paper we analyze the impact of resonator parameters on the performance of the piezoelectric resonator based dc-dc converter, derive the optimal load impedance and efficiency limits, and analyze the impacts of varying conversion ratio and load impedance. This work is accompanied by a prototype dc-dc converter using a piezoelectric resonator fabricated from lithium niobate. The piezoelectric resonator has a quality factor of 4178 and a coupling coefficient, $k_t^2$ , of 29%. The converter is able to achieve high efficiency zero voltage switching and a continuously variable conversion ratio without the use of any discrete inductors. It achieves a maximum power output of 30.9 W at an efficiency of 95.2% with a power density of 6.76 $\frac{\text {W}}{\text {cm}^3}$ .

A Hybrid Class-E Topology With Constant Current and Constant Voltage Output for Light EVs Wireless Charging Application

Abstract: Traditional Class-E circuit features fewer components, high reliability, and soft switching. However, due to the unidirectional excitation, the application of such a topology circuit is limited, i.e., usually used in low-power applications. To relieve this issue, this article proposes a switched-capacitor-based Class-E circuit, to extend the operating power range of the Class-E circuit. With the proposed new circuit, both constant current (CC) and constant voltage (CV) output modes can be achieved by switching the branch once without changing the switching frequency or compensation network. Compared with the existing CC and CV charging strategies, the proposed circuit has the advantages of fewer components, simpler implementation, and higher reliability. Moreover, the studied compensation network can also be extended to other inverter topologies. The working principle of the proposed circuit is described in detail, and the variable zero-voltage switching (ZVS) margin is introduced to make an accurate design of parameters. Subsequently, the influence of high-order harmonic components on the circuit and the sensitivity of parameters are analyzed. Finally, the proposed circuit is simulated and experimented on a 180–450-W prototype with CC and CV characteristics to verify the feasibility of the circuit and the accuracy of theoretical analysis.

Flux-pumped impedance-engineered broadband Josephson parametric amplifier

Abstract: Broadband quantum-limited amplifiers play a critical role in the single-shot readout of superconducting qubits, but a popular implementation, the traveling wave parametric amplifier, involves a complex design and fabrication process. Here, we present a simple design for a Josephson parametric amplifier, using a lumped element resonator comprising a superconducting quantum interference device whose useful bandwidth is enhanced with an on-chip impedance-matching circuit. We demonstrate a flux-coupling geometry that maximizes the coupling to the Josephson loop and minimizes spurious excitation of the amplifier resonant circuit. The amplifier, which operates in a flux-pumped mode, is demonstrated with a power gain of more than 20 dB over a bandwidth of about 300 MHz, where approximate noise measurements indicate quantum-limited performance. A procedure is given for optimizing the bandwidth for this kind of amplifier, using a linearized circuit simulation while minimizing non-linearities.

Series Synchronized Triple Bias-Flip Circuit: Maximizing the Usage of a Single Storage Capacitor for Piezoelectric Energy Harvesting Enhancement

Abstract: The synchronized multiple bias-flip (SMBF) interface circuits enhance the piezoelectric energy harvesting (PEH) capability by maximizing the extracted energy from the piezoelectric source and simultaneously minimizing the dissipated energy in the power conditioning circuit. They provide the most energy-economic solution for the piezoelectric energy harvesting enhancement. However, the growing scale of the switches network and the increasing number of bias voltages have added much complexity to the circuit design and control. In this article, we reduce the number of passive components to the biggest extent by maximizing the usage of a single capacitor, which simultaneously acts as an energy storage and provides two nonzero bias voltages. Together with the free zero-volt bias, triple bias-flip actions (S3BF) are realized in the new design. Compared with other single-capacitor designs, it makes the best energy harvesting capability so far. Moreover, the proposed series S3BF circuit can automatically shift among single, double, and triple bias-flip operations under heavy-, medium-, and light-load conditions, respectively, which is unprecedented in the previous designs. Theoretical and experimental results show that the harvested power can always follow the maximum power envelope of the single, double, or triple bias-flip operations.

Voltage-Mode Elliptic Band-Pass Filter Based on Multiple-Input Transconductor

Abstract: This paper presents a new voltage-mode elliptic band-pass filter based on a multiple-input transconductor (MI-OTA). The MI-OTA’s structure employs the multiple-input MOS transistor technique that simply enables to increase the number of OTA’s inputs without increasing the number of current branches or the differential pairs. The MI-OTA features high linearity over a wide input range with a compact and simple CMOS structure. From the advantage of multiple inputs, it enables to construct the arbitrarily summing and subtracting under the proposed voltage-mode filter design procedure. The filter is designed and simulated in Cadence environment using $0.18~\mu \text{m}$ TSMC CMOS technology. The filter offers 72.9 dB dynamic range for 2 % total harmonic distortion (THD) for sine input signal of 0.5 Vpp @ 1kHz with voltage supply ± 0.9V. The simulation results of the filter are in agreement with the RLC prototype. The experimental results using commercially available IC are also included to confirm the proposed filter that are in good agreement with the simulation results.

A memristive RLC oscillator dynamics applied to image encryption

Abstract: One of the major challenges in chaos dynamics is the design of simple and realisable electronic circuits capable of complex dynamic behaviours. Our contribution studies the dynamics and implementation of a simple chaotic memristive RLC oscillator circuit of jerky type as well as its application in designing image cryptosystem. The proposed circuit consists of an operational amplifier and an RLC network, comprising a resistor, an inductor, and two capacitors. Considering the crucial role of symmetry in physical, chemical, biological, and mechanical systems, a voltage control memristor emulator is employed to induce symmetry in the proposed circuit. For the dynamic analysis, fourth-order differential equation with exponential nonlinearities is used. Furthermore, standard analysis tools such as Lyapunov spectrum, bifurcation analysis, and phase space trajectories are employed. The phase space is magnetized using four symmetric attractors coexisting for the same set of parameters and different initial conditions indicate the symmetricity of the proposed system. Meanwhile, asymmetric attractor is capable of merging into one symmetric attractor through an attractor-merging bifurcation. Extensive experimental validations of these properties via PSPICE simulations and by using real electronic components are reported. Finally, the chaotic sequences emanating from the proposed oscillator are exploited to design an encryption algorithm that is subsequently validated via simulations and standard image security analysis with prominent outcomes in terms of very low encryption time (0.0746s for 128 × 128 colour image), mean entropy of 7.999 and mean NPCR of 99.62% just to name a few.

Multimode Constant Power Control Strategy for LCC Resonant Capacitor Charging Power Supply Based on State Plane Analysis

Abstract: A novel constant power charging strategy is proposed for LCC resonant capacitor charging power supply (CCPS) in this article, which combines the advantages of discontinuous current mode (DCM) and continuous current mode (CCM) to increase the charging speed of capacitor and the utilization of input grid capacity. In order to implement the multimode constant power control (CPC) strategy, a steady-state model of LCC series-parallel resonant converter is built by state plane analysis, and the analytical expressions for output voltage, average output current, and switching frequency are derived. By the analytical expressions, this control strategy directly determines the relationship of the output voltage and the switch frequency, so the frequency control curve of the pulse frequency modulation could be realized easily. Accordingly, the converter operating along the control curve can take advantage of high average and low peak current of CCM, small switching loss of DCM. Finally, the accuracy of LCC state plane model and the effectiveness of multimode CPC are verified by the simulation and a 2-kW CCPS experiment.

Active Power Decoupling Control for Single-Phase Current Source Rectifier Based on Emulating LC Resonator

Abstract: The ripple power with double grid frequency inherently exists in a single-phase current source rectifier. To achieve the constant dc-link current, an alternative way is to use an LC resonator tuned at 100 Hz to block the ripple power. However, this method requires large passive components, which will degrade the power density and even the reliability. What is worse, the decoupling performance will be deteriorated when the parameter drifts happen. In this letter, a control strategy based on emulating the output voltage characteristic of the LC resonator is proposed. Then, the decoupling function as the same with using a real LC resonator is achieved. At the same time, no bulky passive components are needed and the issue caused by parameter drifts is also avoided. In addition, the modular design of the LC emulator can be achieved. A prototype was built to verify the effectiveness of the proposed method.

Tractable Resonant Circuit With Two Nonuniform Beams for a High-Power 0.22-THz Extended Interaction Oscillator

Abstract: In vacuum electronics, the influence of the uniformity of electron beams on the performance of two- or multi-beam devices is a key scientific problem in the development of compact, high power millimeter-wave and terahertz (THz) sources. In this letter, we focus on this problem in extended interaction oscillators (EIOs) and propose a tractable extended resonant circuit that has no requirement for the uniformity of beams. The circuit design builds up a TM13 mode mechanism to support two nonuniform beams, based on maintaining the same electromagnetic characteristics of conventional resonant circuits used in single-beam EIOs. To verify this idea, we designed and simulated a 0.22-THz EIO with the proposed circuit. As the current of one beam is I1 and that of another beam is increased from 0 to 4I1, the EIO has shown the behavior of linearly increasing the output power and then becoming saturated through particle-in-cell (PIC) simulations. The ideal case is the currents of the two beams are the same at the same voltage to drive the EIO. This case can reduce the high current density required for start oscillation in single-beam EIOs and obtain high power. Simulation results show that the power of 0.22-THz wave over 1.32 kW is obtained using double beams at 22.2 kV and each current of 0.25 A.

Extensible Multi-Input Synchronous Electronic Charge Extraction Circuit Based on Triple Stack Resonance for Piezoelectric and Thermoelectric Energy Harvesting

Abstract: At present, research on interface circuits for environmental energy harvesting is mainly carried out around a single transducer However, rich ambient energy sources can be harvested with multiple transducers Hence, in this article, extensible multi-input synchronous electronic charge extraction (EMI-SECE) interface circuit based on triple-stack LC resonance for piezoelectric and thermoelectric energy harvesting is proposed proposed EMI-SECE interface circuit can simultaneously extract energy from multiple piezoelectric transducers (PZTs) and thermoelectric generators when the peak open-circuit voltage of the PZTs is detected by the passive peak detectors Theoretical analysis and experiments verify the effectiveness of the circuit The experimental results show that the proposed EMI-SECE circuit can harvest energy from two PZTs with any phase difference (0−2 π ) based on single inductor In addition, the circuit can harvest thermoelectric energy at an open-circuit voltage as low as 20 mV, and the maximum harvesting efficiency can be reached 857% at $V_{{\rm{oc}}}$ = 200 mV

Performance investigations of nonlinear piezoelectric energy harvesters with a resonant circuit under white Gaussian noises

Abstract: Vibration-based piezoelectric energy harvesting for powering low-energy consuming electronic equipment has received a great deal of attention in the last decade. Most researches applying deterministic approaches or theory of random vibrations have been concentrated on examining the performance of the piezoelectric energy harvesters with a purely resistive circuit under harmonic or random excitations. Here, the ambient excitations are assumed to be white Gaussian noises, we investigate a nonlinear piezoelectric energy harvester which utilizes a harvesting circuit with both a resistive load and an inductor, based on the fact that previous research has demonstrated that the intentional introduction of an inductor substantially improves the performance of energy harvesting device. Two scenarios, namely the purely inductive circuit and the resistive–inductive circuit, are examined. Exact stationary solution of the output voltage and closed-form expression of the mean square voltage are acquired for the purely inductive circuit. By combining the equivalent linearization method and the moment method of random process theory, analytical solutions of mean square voltage and averaged power output involving dimensionless parameters of the electromechanical system are derived for the resistive–inductive circuit. The energy conversion efficiency is analyzed by means of energy balance equation. Monte Carlo numerical simulations are implemented to validate the theoretical predictions. Results reveal unique characteristics of the nonlinear vibration systems with a resonant circuit, showing its superiority over the energy harvesters with a purely resistive circuit. The present study provides a paradigm in a simple but effective way to resolve strong electromechanical coupling systems under random excitations.

Soft-Switching Current-Source Rectifier Based Onboard Charging System for Electric Vehicles

Abstract: In this article, a novel soft-switching current-source rectifier (CSR) based bidirectional on-board charger (OBC) system is proposed for electric vehicles (EVs) comprising multiple battery sets. Besides the CSR's inherent advantages of higher-quality input voltage waveforms, enhanced short-circuit-current tolerant capability and long lifetime of dc choke, the cascaded configuration of dc choppers can implement the higher dc-link voltage with multiple low-voltage battery sets, and the low-voltage devices can be used. With the auxiliary resonant circuit in dc link, the soft-switching operation can be achieved for all power switches in the proposed power conversion circuits. Moreover, the high dv/dt caused by high-speed switching silicon carbide devices can be reduced with the capacitor in the auxiliary circuit. The collaborative operation strategy is proposed for the CSR and the dc choppers, which enables reduction of switching frequency of dc choppers and current ripple in dc link simultaneously. The experimental results are presented to verify the performance of the proposed the OBC system.

Research on a Novel High-Efficiency Three-Phase Resonant Pole Soft-Switching Inverter

Abstract: A high-efficiency three-phase resonant inverter is presented to optimize the performance of the inverter. When the auxiliary resonant circuit on each phase bridge arm works in the commutation process of the inverter, the voltage across resonant capacitors in parallel with main switches will form zero state periodically. In this case, main switches can achieve zero-voltage soft-switching. Meanwhile, auxiliary switches can achieve zero-current turn on and zero-voltage turn off during the operation of the auxiliary resonant circuit. Soft-switching can reduce switching loss and make the inverter work efficiently. The novelty of the inverter mainly reflects in the simple structure of the auxiliary circuit and the simple control method of auxiliary switches. This article analyzes the working mode of the circuit and the realization condition of soft-switching. Meanwhile, it discusses theoretical calculation of the power loss of the auxiliary circuit. The experimental results on the 3-kW prototype show that switching devices work in the soft-switching state. The efficiency of the prototype under the rated output power reaches 98.7%, which is higher than that of the same type of other soft-switching inverter. Therefore, the topology is valuable for the research and development of the high-performance three-phase inverter.

Behavioral Modeling and Analysis of Ground Current in Medium-Voltage Inductors

Abstract: This letter proposes a behavioral model for analyzing the ground current in medium-voltage (MV) inductors. The impedance between the terminals and the ground connection of inductors is measured by the impedance analyzer, which is capacitive at low frequency. In order to characterize this impedance, a multistage paralleled RLC circuit is proposed. An analytical method is further developed to calculate parameters of the proposed equivalent circuit, which enables to predict the time-domain response of the ground current in MV inductors. A digital twin of the double-pulse-test setup is developed in LTspice, where the simulated ground currents show good agreements with the experimental measurements.

Fault Characteristics and Riding-Through Methods of Dual Active Bridge Converter Under Short-Circuit of the Load

Abstract: The fault riding-through (FRT) capability is a key problem in the dc distribution network. In order to achieve the FRT, it is necessary to analyze the worst-case scenario (WCS) of the short-circuit transient process of distribution components. This article analyzes the whole fault characteristic in a dual active bridge (DAB) in the WCS when a short-circuit occurs on the load at different locations that has not been considered in the existing literature. The short-circuit in the WCS can cause various fault current in the whole circuit, introducing a risk of the overcurrent. In order to overcome this problem, FRT-based methods are proposed in this article. One of the methods is to block the power switches for a certain period and restart the circuit, and another is to add a series output inductor with a reasonable inductance. By these methods, the faulty branch can be cut off by the corresponding circuit breaker in time. The results are verified by the simulations on a 50-kW DAB by MATLAB/Simulink, and the experiments on a 3-kW prototype. The results presented in this article provide a theoretical reference for FRT of DABs.

Electrical Circuits RC, LC, and RLC under Generalized Type Non-Local Singular Fractional Operator

Abstract: The current study is of interest when performing a useful extension of a crucial physical problem through a non-local singular fractional operator. We provide solutions that include three arbitrary parameters α, ρ, and γ for the Resistance-Capacitance (RC), Inductance-Capacitance (LC), and Resistance-Inductance-Capacitance (RLC) electric circuits utilizing a generalized type fractional operator in the sense of Caputo, called non-local M-derivative. Additionally, to keep the dimensionality of the physical parameter in the proposed model, we use an auxiliary parameter. Owing to the fact that all solutions depend on three parameters unlike the other solutions containing one or two parameters in the literature, the solutions obtained in this study have more general results. On the other hand, in order to observe the advantages of the non-local M-derivative, a comprehensive comparison is carried out in the light of experimental data. We make this comparison for the RC circuit between the non-local M-derivative and Caputo derivative. It is clearly shown on graphs that the fractional M-derivative behaves closer to the experimental data thanks to the added parameters α, ρ, and γ.

Online ESR Monitoring of DC-Link Capacitor in Voltage-Source-Converter Using Damping Characteristic of Switching Ringings

Abstract: Online monitoring of dc-link capacitor's equivalent series resistance (ESR) could provide valuable and timely information for power converter failure prognosis and predictive maintenance. The conventional ESR estimation methods are mainly based on pulsewidth modulation (PWM) voltage and current ripples (ESRaΔ u c/Δ i c), but the performance is affected by operating conditions (especially at light-load), quasi-resonance effect and sensor amplitude error. To overcome these difficulties, an online ESR monitoring method is proposed using the damping characteristic of dc capacitor switching ringings. The intrinsic high-frequency (HF) resonance incidents between the power device fast switching and converter parasitic parameters are utilized in this article. First, the mechanism of dc capacitor switching ringing is analyzed by the HF resonance equivalent circuit. The analytic relationship between the damping characteristic and the ESR is established. Then, the condition monitoring (CM) scheme, noncontact HF sensor, and half-power bandwidth algorithm for ESR estimation are presented. Finally, an experimental study is carried out to validate the feasibility and effectiveness. The damping of switching ringing is inherently sensitive to the ESR of dc capacitor under the condition of resonance. Both theoretical analysis and experimental results confirm that the proposed method can achieve mΩ-level accuracy and good robustness under different conditions.

Magnetic Sensor Based on Giant Magneto-Impedance in Commercial Inductors

Abstract: Magnetic sensors have various applications in navigation, power distribution, robotics, factory automation, and medical diagnosis. The development of highly sensitive magnetic sensors usually requires complicated and costly fabrication process. Herein, we report giant magneto-impedance of 41036% in the commercially available ferrite core inductors. A magnetic field detection limit of 10 nT at 1 Hz has been obtained by directly measuring the impedance of the as-obtained inductor without any optimization. With a 100 pF capacitor in series connection with the inductor where lower impedance facilitates the measurement process, a limit of detection of 625 pT at 1 Hz has been obtained in the series RLC resonator. These results can be understood in terms of the magnetic field-dependent self-resonance in the inductors which act as lumped RLC resonators. Compared with the traditional electromagnetic induction sensing mode, the magneto-impedance sensing mode shows 5000 folds improvement in the magnetic field detection capability.

Minimizing Current in Inductive Power Transfer Systems With an Asymmetrical Factor for Misalignment Tolerance and Wide Load Range

Abstract: In inductive power transfer (IPT) systems, misalignment and wide load range can lead to high current and control complexity. This can affect the performance of high-power systems. In this article, a method to minimize converter and primary resonant circuit currents based on an asymmetrical factor is proposed to improve IPT system performance over wide misalignment and load ranges. The proposed asymmetrical factor incorporates two design variables: an asymmetrical voltage factor and an asymmetrical compensation factor. These help to minimize current from two perspectives. First, they tend to redistribute zeroes and poles for power versus frequency characteristics. The power characteristic can be asymmetrical and monotonic over the working switching frequency range. Second, the input impedance angle can become insensitive to coupling factor and to load by adjusting the frequency that corresponds to the minimum input impedance angle. The current increases by only 15% over a 2:1 coupling coefficient variation range at rated load. Analysis and design guidelines are presented for the proposed method. A 2.1-kW prototype has been prepared to verify the approach.