Search

Contribution: Two general rules for calculating, in the time domain, step discontinuities of voltages and currents in electric circuits, combining physical principles and basic mathematical treatment. The two general rules, resulting from a formal method of analysis, provide a straightforward way to update the states of a circuit, immediately after the occurrence of switching or impulsive excitation. Among its advantages, they can be used to simplify the numerical simulation of elaborate circuit topologies by avoiding approximate models of impulsive sources or switches. Background: In most engineering undergraduate textbooks, the effects of switching and impulsive sources on higher order electric circuits are usually studied for the particular case of linear time-invariant (LTI) circuits in the Laplace transform domain. This approach, however, can be time consuming and demands little reasoning on the physical principles of circuit operation. Moreover, it is not adequate for linear time-variant or nonlinear circuits. Intended Outcomes: Step discontinuities in electric circuits, caused by switching or impulsive sources, are identified and calculated through the method, allowing complete responses to be obtained afterward. Not only can the method be extended to linear time-variant and nonlinear circuits but it also has interesting consequences in numerical simulation of circuits. Application Design: An application exercise and a set of conceptual questions on the subject were proposed to electrical engineering students. Findings: The analysis of the educational experiment indicates that applying the method presented herein improves the students’ ability to obtain initial conditions of circuits, being a more straightforward and effective approach than using Laplace transform techniques. [ABSTRACT FROM AUTHOR]

In many technical applications at low frequency, wave propagation effects can be neglected, and Darwin models promise to accurately describe the electromagnetic fields because they include resistive, inductive, and capacitive terms. In a former work, we developed an efficient, frequency stable method to solve the full Maxwell model, i.e., without neglecting any effect. This method employs the electro-quasistatic gauge, which allows to cleanly separate the calculation of capacitive effects in a first step, from the calculation of inductive effects in a consecutive second step. The Darwin model in frequency domain and electro-quasistatic gauge can easily be derived from this method by neglecting just one term, namely the induced displacement current. Here, we compare this Darwin model with the full Maxwell model, e.g., for the example of an $RLC$ -series circuit. We found that this Darwin model cannot describe the interaction between $L$ and $C$ in the $RLC$ -circuit. [ABSTRACT FROM AUTHOR]

A second-order analytic extension of eigenvalue (AEE) method is presented and investigated for efficiently computing the Z- parameters of passive RF circuits over a wide frequency band with full-wave accuracy. The Z - parameters of an RF circuit are first extracted based on a full-wave simulation on sampling frequencies and then decomposed into eigenmodes, whose eigenvalues are analytically extended to all other frequencies within the frequency band of interest based on functional equations constructed from second-order series and parallel RLC circuits. An eigenvector-eigenvalue identity is adopted to compute the frequency-dependent eigenvectors from the eigenvalues of the submatrices, which are used in the expansion of the Z - parameters. A comparison with full-wave solutions is given for the second-order AEE where four frequencies are employed to accurately approximate the Z - parameters and predict the frequency response over the entire band of interest that goes to much higher frequencies than the first-order AEE. With this, the previously developed first-order AEE for a quasi-static analysis is successfully extended to much higher frequencies. Numerical examples are provided to validate the accuracy and demonstrate the capability of the second-order AEE. It is found that the second-order AEE is very accurate for modeling RF circuits with electrical sizes up to one wavelength that possibly contains resonances, as compared to the first-order AEE, which is applicable only to RF circuits with electrical sizes smaller than one-tenth to one-fifth of a wavelength that contains no resonance. [ABSTRACT FROM AUTHOR]

Practical superconducting quantum interference devices (SQUIDs) have been developed into multiloop hybrid electric circuits with Josephson junctions and normal elements such as resistor, inductor and capacitor. To find a common circuit analysis and simulation method for different types of SQUID hybrid circuits consist of both superconducting and normal components, we introduce a mesh-current method, which can derive both the general system model and uniform circuit equations directly from the equivalent circuit. The mesh-current method is demonstrated in the simulation of a SQUID additional positive feedback circuit. The numerical simulation results are presented and verified with the measurements. Compared with the conventional nodal analysis method, the mesh-current method is excellent in dealing with the relations including external flux, self and mutual inductances in multiloop hybrid circuit analysis; its final circuit equations directly exhibit the physical theorems; its general system model reveals the quantum interference mechanism inside SQUID circuits, and is applicable for further dynamics studies. [ABSTRACT FROM AUTHOR]

A novel numerical method has been developed that incorporates electrically conducting objects into particle-in-cell simulations of electrostatic plasma. The method allows multiple objects connected by voltage and current sources in an arbitrary circuit topology. Moreover, by means of an unstructured mesh, the objects can have arbitrary shapes. The electric potential of the objects is solved self-consistently by incorporating charge constraints into the finite element discretization of the Poisson equation. This method has been implemented in a new code, Particles-in-Unstructured-Cells (PUNC), suitable for rapid prototyping. The flexibility of this code has proven convenient to survey various methods, and an issue of reduced convergence rate of today’s unstructured plasma–object interaction codes is highlighted. The results for a conducting sphere immersed in the Maxwellian plasma are in good agreement with previous studies. [ABSTRACT FROM AUTHOR]

Contribution: A didactic methodology, based on analytical expressions and experimental validation, to describe the process of abrupt current interruption in a series RL circuit, that considers real passive components and uses a toggle switch as disconnecting device. Background: In undergraduate courses, circuits adopted in transient analysis usually assume electrical switches in their ideal form, disregarding electrical impedance and its variation over time. Texts and instructors rarely point out these simplifications, so students can become confused. There is thus a need for a suitable switch model that yields a behavior consistent with real devices, while permitting a mathematical formulation of the inductor current. Intended Outcomes: That students should understand electrical component modeling, and how models can represent the physical phenomena that occur in electrical circuits. Application Design: An experiment, designed to evaluate students’ perceptions of switch modeling, modeled a switch by using three different equivalent circuits of increasing complexity, to allow a more realistic simulation. Electrical switch modeling is described, with the models being based on measurements performed on a real circuit. Findings: Student performance was evaluated qualitatively through test scores, and quantitatively through a post-class questionnaire. The results indicate that 96.15% of the students were able to propose an accurate model of the electrical switch. [ABSTRACT FROM AUTHOR]

In this paper, a new step-up dc–dc converter module that consists of three resonant submodules interconnecting with 1:1 turns ratio three-phase transformer and coupled current-fed voltage doubler modules is presented for medium voltage dc converter design in wind energy application. By utilizing step-up resonant circuits with three-phase transformer and combining it with a “multistring” inverter, the proposed circuit structure completely utilizes all the switching circuits to transfer power to the output. In addition, the proposed topology is able to achieve high voltage gain without using large turns ratio high frequency step-up transformers. Zero voltage switching turn-on and near zero current switching (ZCS) turn-off are maintained for all the switches. A modular 1.5 MW, 1 kV (dc-link), 20 kV (output) converter system is presented to validate the performance of the proposed circuit. Experimental results on a laboratory-scale 2.8 kW, 0.3 kV (dc-link), 6 kV (output), prototype are provided to highlight the merits of this work. Silicon Carbide (SiC) MOSFETs and SiC Schottky diodes are utilized in both designs. Results confirm that a peak efficiency of 97.6% is achieved in the prototype. [ABSTRACT FROM AUTHOR]

This paper proposed a method of synthesizing absorptive common-mode filters (A-CMFs) analytically with high absorption efficiency and two designable absorption bands. The proposed method is carried out by a novel circuit architecture and its analysis procedure. In differential mode, the integrity of the differential signals is maintained, and in common mode (CM), two absorption frequency bands can be obtained theoretically. These bands are designable with the analytical equations derived in this paper, so a dual-band or broadband A-CMF design can be easily synthesized by our proposed method. The authors also show that this method can make any one of R-CMFs “upgrade” to an A-CMF by simply adding an additional circuit, and this might be a revolutionary progress for the currently used CM-suppression techniques. To make the proposed concept more understandable, an example is used to demonstrate how the synthesizing methodology works, where a broadband A-CMF with its absorption bands located at 2.4 and 3.6 GHz is designed and implemented. Furthermore, a test sample of this A-CMF is fabricated on a four-layer printed circuit board. It is measured on a probing station, and the measured results are very similar to the simulated results. Finally, a comparison table of all the related works is given, showing that this proposed method really makes a significant improvement for A-CMF techniques. It is worth noting that this circuit design can provide a broadest 95%-absorption band to our best knowledge. [ABSTRACT FROM AUTHOR]

Dense smoke from wildfires within a 500-kV line corridor led to several line protection trips over a three-day period. A switchable line-connected reactor, provided to control Ferranti voltages, tripped and locked out twice by its protection shortly after the line was de-energized. Lockout operation prevented quick reactor reinsertion and impeded operational flexibility until visual inspections of the reactor were conducted on both occasions. Forensic investigation of the event concluded that the smoke increased the line capacitances. This created a near 60-Hz zero sequence resonant circuit when the line tripped and became de-energized along with the reactor. The resonant circuit amplified the capacitively coupled zero sequence 60-Hz voltage induced from circuits which run adjacent to the line for a short distance. The voltage amplification drove enough current through the reactor to trip the sensitive ground overcurrent protection. A holistic mitigation is designed to avoid reoccurrence of the incident and improve overall line reliability. The intent of this paper is to share lessons learned from the event investigation with peer utilities because this problem of unexpected operation of line shunt reactor protection has not previously been reported. [ABSTRACT FROM AUTHOR]

Power converters in the system-level real-time simulation are usually emulated by L/C-based associated discrete circuit (L/C-ADC). However, the L/C-ADC approaches may suffer from two issues: How to mitigate the unacceptable virtual power loss especially in high-frequency applications, and how to tune LC parameters setting which is affected by the external circuit. This paper proposes a novel generalized associated discrete circuit (G-ADC) model with parameterized history current sources. By utilizing the stability region of the feasible parameter space, the optimized G-ADC models with the best damping characteristic are developed for both two-level and three-level converters. The analytical results also guarantee that the parameters of the optimized G-ADC model are independent of the external circuit for most power grid applications. Furthermore, an field programmable gate array (FPGA)-based real-time simulation platform is built to verify the feasibility of the proposed scheme. Extensive simulation and hardware-in-loop experiment results demonstrate the effectiveness and superiority of best-damped models as well as the modeling flexibility corresponding to insensitivity to operating conditions and external system parameters. [ABSTRACT FROM AUTHOR]

The aim of the present paper is to develop methods that would be able to predict transient voltage distribution along the insulated-multiconductor windings of electric equipment fed by frequency converters. Several electromagnetic (EM) challenges are presented with this desire. First, the resistance (R) and self-/mutual inductances (L,M) frequency-dependent parameters are accurately computed using the enforced electric total current process based on the finite-element (FE) formulation of the strongly coupled time-harmonic magnetic field and total current density equations model including skin and proximity effects. Second, the coupling capacitances (C) are computed from the FE electrostatic analysis using the floating electric scalar potential process. Finally, a realistic high-frequency electric circuit of the distributed (R, L, M, C) EM parameter matrices is formed in order to predict the turn-to-ground and turn-to-turn voltage transients. The numerical results obtained from the proposed models implemented under the MATLAB code are successfully verified by the corresponding laboratory test measurements. [ABSTRACT FROM AUTHOR]

Power electronic transformer (PET) composed of modular dual active bridge (DAB) blocks has a promising future in ac–dc hybrid distribution network because of its energy routing ability. The key element that restrains the development of PET is the vulnerability of power electronic devices during faults, especially dc faults. DC faults (mostly line faults) have very short transient process and no obvious fundamental frequency, which means fault location is difficult to be realized for dc lines in distribution network. Considering that fault location plays an important role in realizing fast fault clearance and recovery, this paper analyzed fault characteristics of dc line faults with respect to the basic structure of modular DAB block and proposed a two-terminal fault location method based on transient voltages measured in dc line boundaries. To evaluate the validity of proposed method, numerical simulations with different fault conditions were implemented in PSCAD/EMTDC. The simulation results indicate that the proposed fault location method located the faulted point quickly and correctly. [ABSTRACT FROM AUTHOR]

Today's implantable mechanical circulatory support devices, such as left ventricular assist devices, still rely on a percutaneous driveline, which is a frequent cause of severe infections and which reduces the quality of life for the patients. Inductive power transfer (IPT) is therefore a promising technology to replace the driveline and, hence, reducing the likelihood of an infection. This paper focuses on the series–series compensated IPT system and provides an in-depth comparison of two operating modes, i.e., the operation at resonance and the operation above resonance, and highlights the advantages and disadvantages with respect to the requirements set by the application at hand. In addition, the paper presents the design and the realization of a fully functional transcutaneous energy transfer (TET) implant hardware prototype, which includes the IPT front-end, the control circuit, the backup battery and its charging converter, as well as the communication electronics in a boxed volume of only 10.3 cl. The experimental verification shows that overall dc–dc efficiencies of up to 90% can be achieved for both operating modes when transmitting 25–30 W from the external battery to the implant backup battery, each having a nominal voltage of 14.8 V, using TET coils with 70 mm diameter and 10 mm coil separation distance. [ABSTRACT FROM AUTHOR]

The power conditioning interface circuit plays a crucial role in the energy harvesting (EH) capability enhancement in piezoelectric EH (PEH) systems. The principle of most existing synchronized switch circuits for PEH enhancement was summarized under the recently introduced synchronized multiple bias-flip (SMBF) model. The optimal bias-flip strategy derived from SMBF provides valuable insights for future circuit development. Based on such theoretical foundation, this paper implements a new interface circuit called theparallel synchronized triple bias-flip(P-S3BF) for further boosting the harvesting capability beyond the state-of-the-art solutions. By sophisticatedly allocating more bias-flip actions, it makes the best compromise between higher extracted power and lower dissipated power for power conditioning, toward maximum net harvested power. Moreover, the bias voltage reference in P-S3BF is self-contained and self-adaptive. Compared to the other existing solutions involving active voltage manipulations, these two conveniences brought in by P-S3BF are the most significant and necessary features, which facilitate the practical stand-alone implementation of P-S3BF under different periodic vibrations. Experimental result shows that, with the piezoelectric cantilever in use, which vibrates at a constant deflection magnitude, the P-S3BF circuit harvests 24.5% more power than its single bias-flip counterpart, the extensively studied parallel synchronized switch harvesting on inductor; and 287.6% more power than its null bias-flip counterpart, the standard EH bridge rectifier. [ABSTRACT FROM AUTHOR]

Piezoelectric vibration energy harvesting has drawn much research interest over the last decade toward the goal of enabling self-sustained wireless sensor nodes. In order to make use of the harvested energy, interface circuits are needed to rectify and manage the energy. Among all active interface circuits, synchronized switch harvesting on inductor (SSHI) and synchronous electric charge extraction are widely employed due to their high energy efficiencies. However, the cold-startup issue still remains, since an interface circuit needs a stable dc supply and the whole system is completely out of charge at the beginning of implementations or after a certain period of time without input vibration excitation. In this paper, a new cold-startup SSHI interface circuit is presented, which dynamically increases the open-circuit voltage generated from the piezoelectric transducer in the cold state to start the system under much lower excitation levels. The proposed circuit is designed and fabricated in a 0.18- $\mu$ m CMOS process and experimentally validated together with a custom microelectromechanical system harvester, which is designed with split electrodes to work with the proposed power extraction circuit. The experiments were performed to start the system from the cold state under variable excitation levels. The results show that the proposed system lowers the required excitation level by at least 50% in order to perform a cold startup. This aids restarting of the energy harvesting system under low excitation levels each time it enters the cold state. [ABSTRACT FROM AUTHOR]

In this paper, a metal object detection (MOD) system, a kind of foreign object detection (FOD), which is based on mistuned resonant circuits and utilizes the variation of self-inductance of a sensing pattern, is newly proposed for wireless electric vehicle (EV) chargers. The sensing pattern that consists of multiple loop coil sets is mounted on the transmitting (Tx) pad of an EV charger, where a loop coil set has two coils connected in series with the opposite polarity to cancel out the induced voltage generated by the Tx coil. Variation of self-inductance of the loop coil set is detected by a parallel-resonant circuit, driven by a current source and operating at near 1 MHz, in order to enhance the resolution of the proposed MOD system. To increase the detection sensitivity of the proposed MOD system, instead of an exact resonant frequency, a mistuned operating frequency near the –3 dB point is utilized for the parallel-resonant circuit. In this way, the proposed MOD system can detect very small metal objects regardless of their position and orientation on the Tx coil without any blind zone. Through simulations and experiments, it is found that the proposed MOD system detects not only horizontal but also standing upright metal objects. A prototype MOD system, operating at 85 kHz to satisfy the standard J2954, was fabricated to verify its feasibility. The results showed that output voltage change of the proposed MOD system becomes 22.7% for a piece of the aluminum foil of 3 × 3 cm2and 40.9% for 100 Korean Won coin. [ABSTRACT FROM AUTHOR]

In this letter, a pulse current injection (PCI) setup involving a pulse generator with adjustable parameters is designed and modeled in SPICE. In order to allow causal and accurate time-domain simulation, the circuit model makes use of an augmented network to approximate the non-rational frequency response of the injection probe. The obtained SPICE model is preliminary validated by measurement for different sets of values of the pulse-generator parameters. Afterward, an explicative example of radiated test setup is considered. The stress waveform induced at the points of entry of the equipment under test by radiation (evaluated either by theoretical prediction or by measurement in a low-level radiation environment) is taken as reference to prove the effectiveness of the proposed PCI-setup model in identifying the values of the generator parameters required to reproduce the same disturbance by PCI. [ABSTRACT FROM AUTHOR]

Circuit models of horizontal and vertical grounding electrodes are traditionally used in high-frequency (HF) analysis, although underlying approximations limit their accuracy in some low-frequency ranges. Recently, a number of new circuit models have been introduced, but the improvement of the accuracy at HF has not been systematically evaluated. In this paper, we show that new circuit models can be directly derived from method of moments solutions of the integral forms of Maxwell equations by introducing different assumptions. This approach helps to categorize different models into only a few categories based on underlying approximations. To determine the applicable range, we analyze the error for impedance to ground computed by different circuit models in comparison to that calculated by a rigorous full-wave model over wide ranges of parameters, such as electrode length, soil resistivity, and frequency. This paper: 1) provides a parametric analysis that enables the estimation of the applicability of the particular circuit model for application to a practical case based on its accuracy; 2) presents a unified systematic approach to derive circuit models with different capabilities; and 3) reveals that the modeling of the mutual coupling between different parts of the grounding electrode is the key factor for radically improving the accuracy of circuit models at HF. [ABSTRACT FROM AUTHOR]

This paper describes the design and implementation of novel trigger circuit (23 kV, $1.7~\mu \text{s}$ , and 0.66 J/pulse) for xenon flash lamp driver. The design is based on a modified flyback circuit in the discontinuous conduction mode to take advantage of both generating the high voltage from the resonance with output capacitor and connecting the series with main pulse circuit using the flyback transformer which can carry the full current of several kiloampere at high-voltage side. This design eliminates the requirement for additional high-voltage protection devices in a xenon flash lamp driver. In addition, the unique high-voltage flyback transformer is designed with high turn ratio and low leakage inductance. The detailed design procedure for the resonant circuit at the output side of the flyback circuit with the permissible range of the parasitic component of the transformer is described on the basis of simplified analysis of resonant circuit. To verify the proposed design, computer simulation based on PSpice software and experiments for the proposed triggering circuit with a main pulse circuit was performed. For the experiment, the trigger circuit is developed with the specification of maximum 23-kV, 0.66-J/pulse output and tested with a xenon flash lamp (Heraeus P4101) driver consisting of a 1.5-kV, 36-kJ/s main pulse circuit and a 2.5-kW (500 V, 5 A) simmer circuit. The experiment is performed in both triggering without the simmer mode and combining the simmer mode. From the simulation and experimental results, it is verified that the triggering circuit can be used effectively, as it exhibits reliable ignition. [ABSTRACT FROM AUTHOR]

In the magnetic resonant wireless power transfer (WPT) technology, system topology is the main factor that determines the WPT characteristics of the system, and recently, various system topologies based on various composite resonant circuits are being applied in WPT applications. This paper groups the composite resonant circuit-based WPT systems into one family and conducts a comprehensive investigation on their topologies and characteristics. First, characteristics of the composite resonant circuits, which are the fundamental circuits of transmitter and receiver of these systems, are investigated; in the process, a calculation method of resonant frequency, current ratio, and quality factor of these circuits are presented and the characteristics of these parameters are clarified. Second, based on that, the composite resonant circuit-based WPT systems are investigated. Possible topologies of these systems are explored and an equivalent system model of these systems is proposed. Based on that, characteristics evaluation expressions of these systems are derived and the optimal design guide of these systems is discussed. Finally, experimental prototypes are constructed and the proposed theory is verified by experiment results. [ABSTRACT FROM PUBLISHER]

A fractional-order capacitor (FOC) plays a vital role in fractional-order circuits. However, the FOC with order $1< \alpha < 2$ based on existing manufacturing schemes can be only operated in milliwatt power level. Thus, the applications of an FOC in power conversion are limited. To solve the problem, this paper proposes a novel method for realizing a high-power FOC with order $1< \alpha < 2$, in which a power converter is applied to emulate the current–voltage characteristic of an ideal FOC, so the rated power of the FOC can be increased greatly and depended on the power converter. The corresponding topology and its control strategy are provided. The available experiments verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper presents a double pile-up resonance energy harvesting circuit that efficiently and simultaneously extracts energy from a piezoelectric transducer (PZT) and a thermoelectric generator. The proposed harvester operates in a double pile-up mode (DPM) to efficiently extract energy from PZT with the enhanced damping force, resulting in a 1452% improvement in power extraction, which is the best performance among the state-of-the-art works. The harvester also operates in a boost converter mode (BCM) without an additional power switch, achieving 75% conversion efficiency at 450- \mu \textW output power. With a single-shared inductor, a simple control scheme enables the harvester to operate in both DPM and BCM by time-multiplexing method, consuming a low quiescent current of 240 nA. The prototype chip fabricated in a 0.18- \mu \textm BCD occupies an area of 1.5 mm $\times $ 1 mm, and it was tested with a 20-nF PZT product (PPA-1001) vibrated by a shaker (Type 4810). [ABSTRACT FROM AUTHOR]

A starting and voltage spike suppression scheme is proposed and investigated in a three-phase isolated full-bridge boost power factor correction (PFC) converter with the passive flyback auxiliary circuit. In steady state, the auxiliary circuit in the PFC converter is operating as a passive clamp circuit, by which the voltage spike across primary side of the power transformer is suppressed, and the absorbed energy can be transferred to the load during one charging period by the resonance of the inductors and capacitors in the auxiliary circuit. In starting state, the output filter capacitor is charged by the flyback inductor in the auxiliary circuit, and the PFC converter can achieve normal starting-up. The operational processes of the PFC converter are analyzed in both steady and starting states. Furthermore, the design considerations of the key parameters are discussed. Finally, experimental study has been done on a laboratory-made three-phase PFC prototype, and the feasibility of the proposed scheme and the validity of the theoretical analysis are verified by the experimental results. [ABSTRACT FROM AUTHOR]

A phase delay analysis is proposed against pursuing a flat group delay response for the design of wideband circuits. While it is believed that a large group delay variation introduces a large data-dependent jitter, this brief reconsiders the effectiveness of the group delay analysis in the evaluation of wideband circuits. Because of its own differentiating nature, the group delay provides a good insight on the delay variation at a vicinity of a certain frequency. However, for certain kind of wideband circuits, the group delay analysis cannot provide a sufficient insight since much of useful information is lost or distorted during the differentiating operation. In this brief, the effectiveness of the phase delay analysis is investigated and comparison with a traditional group delay analysis is presented with a theoretical approach and through a few circuit examples. [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) is a painless, non-invasive brain nerve stimulation technique, which has been a common diagnosis and treatment method for psychiatry and neurology in recent years. Compared with traditional single-channel magnetic stimulation coil, multi-channel coil array can achieve multi-point synchronous stimulation, scanning stimulation, and flexible switching of various stimulation patterns. Therefore, it has a great development prospect. However, the multi-channel TMS device is still in experimental stage due to the complexity of the drive circuit and the electromagnetic coupling between the coils. Aiming at these two difficulties, this paper developed a novel multi-channel TMS device. By using two closely linked coils with opposite rounded direction to replace one coil, the complexity of the drive circuit can be greatly reduced. Then, the experiment was taken to study the effect of electromagnetic coupling on pulse current in different stimulation patterns. The results show that the coupling coefficient between the adjacent coils limits the minimum amplitude ratio of the auxiliary current to main current. Therefore, the measure of reducing the coupling coefficient was studied in detail. Adding a 6.5 cm-high and 1 mm-thick copper plate in the middle of the adjacent coils was proven to be effective by simulation and experiment. [ABSTRACT FROM AUTHOR]

The model order reduction techniques based on the multipoint projection Krylov methods have become the methods of choice to generate large macromodels of multiport RLC circuits. A well-known difficulty with such methods lies in the need for clever point selection to attain model compactness and accuracy. In this paper, we present an automatic methodology for optimizing sample point selection. This method is general, suitable for circuits obtained by the partial element equivalent circuit method coupled with an adaptive multilevel fast multipole method. Our algorithm has been validated on an industrial example to demonstrate the accuracy and robustness of the approach. [ABSTRACT FROM PUBLISHER]

The major strengths of inductors in energy density and power density make an inductive pulsed power supply (IPPS) a promising option for pulsed power supplies in an electromagnetic launch system. Among the circuits for an IPPS, the capacitor-aided meat grinder circuits constitute an important branch. An analytical method for the working processes of these circuits is proposed in this paper. The core of this method is the decoupling of a high-order circuit into the superposition of a resistor–inductor first-order equivalent subcircuit and a resistor–inductor–capacitor second-order equivalent subcircuit. The validity and accuracy of this method have been verified through comparison with a numerical simulation. The results show that this method possesses both satisfactory accuracy and excellent computational speed. With the same circuit parameters and time step, the time cost of this method is three orders of magnitudes lower than the time cost of a numerical simulation. Moreover, this method contributes to more intuitive understanding and more essential insight into the working principles of the capacitor-aided meat grinder circuits. [ABSTRACT FROM PUBLISHER]

An inductive coil gun is a solenoid surrounding a cylindrical metallic armature (the projectile), both electromagnetically coupled. One or more capacitors discharge a stored voltage quickly through the coil, configuring a kind of RLC circuit, with the pulse-shaped current generating a magnetic field inside the coil that accelerates the projectile. Once the projectile crosses an equilibrium point inside the coil, the existing magnetic field pulls the armature back, therefore reducing the final muzzle velocity and decreasing the efficiency—defined as the ratio between the available capacitor electrostatic versus the slug kinetic energies. This paper describes a system that monitors the armature position inside the coil, with a laser beam, and automatically cuts the current when the projectile reaches the equilibrium point. The system, named current switch circuit, enables higher velocities using the same set of coilgun and projectiles, providing a higher efficiency. [ABSTRACT FROM PUBLISHER]

The partial element equivalent circuit (PEEC) method is a well-established technique for obtaining a circuit equivalent for an electromagnetic problem. The time domain solution of such models is usually performed using nodal voltages and branch currents, or sometimes charge and currents. The present paper describes a possible alternative approach, which can be obtained expressing and solving the problem in the waves domain. The digital wave theory is used to find an equivalent representation of the PEEC circuit in the wave domain. Through a pertinent continuous to discrete time transformation, the constitutive relations for partial inductances, capacitances, and resistances are translated in an explicit form. The combination of such equations with Kirchhoff laws allows to achieve a semiexplicit resolution scheme. Three different physical configurations are analyzed and their extracted digital wave PEEC models are simulated at growing sizes using the general-purpose digital wave simulator. The results are compared to those obtained by using standard SPICE simulators in both linear and nonlinear cases. When the size of the model is manageable by SPICE, an excellent accuracy and a speed-up factor of up to three orders of magnitude are observed with much lower memory requirements. A comparative analysis of results including the effect of parameters like the simulation time step choice is also presented. [ABSTRACT FROM AUTHOR]

A novel voltage-doubling circuit with parallel-resonant dc–dc converter is proposed. The converter consists of full-bridge inverter, resonant tank, high-frequency high-voltage transformer, and voltage-doubling circuit. In the high-voltage applications, low-output voltage ripple has been given much attention. The output voltage step-up ratio is increased by two parts. One is a high-frequency high-voltage transformer and the other is a voltage-doubling circuit. The novel voltage-doubling circuit can not only reach a higher output voltage but also reduce output ripple to a lower level than the conventional one. Therefore, while maintaining the same output voltage, the transformer's turn ratio can be reduced compared with the conventional voltage-doubling circuit. The output power can be adjusted by the phase-shift control technique. In addition, combining this technique with the parallel resonant tank can make all the switches achieve zero voltage turn on (ZVS). The operating principles, steady-state analysis, and the parameter designs are discussed in this paper. Finally, a prototype circuit with 400-V input voltage, 40-kV output voltage, and 300-W output power is developed in the laboratory to verify the performance of the proposed converter. [ABSTRACT FROM PUBLISHER]

Piezoelectric vibration energy harvesters have been widely researched and are increasingly employed for powering wireless sensor nodes. The synchronized switch harvesting on inductor (SSHI) circuit is one of the most efficient interfaces for piezoelectric vibration energy harvesters. However, the traditional incarnation of this circuit suffers from a significant start-up issue that limits operation in low and variable amplitude vibration environments. This paper addresses this start-up issue for the SSHI rectifier by proposing a new architecture with SSHI startup circuitry. The startup circuitry monitors if the SSHI circuit is operating correctly and re-starts the SSHI interface if required. The proposed circuit is comprehensively analyzed and experimentally validated through tests conducted by integrating a commercial piezoelectric vibration energy harvester with the new interface circuit designed in a 0.35- \mu \text m HV CMOS process. Compared to conventional SSHI rectifiers, the proposed circuit significantly decreases the required minimum input excitation amplitude before energy can be harvested, making it possible to extract energy over an increased excitation range. [ABSTRACT FROM PUBLISHER]

High-Voltage pulse generators are commonly used in biotechnology, medicine, industrial applications, food processing and drinking water purification. The dc-dc boost converter has been used before in pulsed applications for its ability to amplify a relatively low input dc voltage to a high-voltage output. A high-voltage solid-state chopping switch is then used to chop the generated high output voltage. In this work, a boost-converter based ringing circuit with high voltage gain is proposed for water treatment applications. The basic concept of the proposed approach depends on operating the boost converter under discontinuous current conduction. With the proposed approach, the chopping high-voltage switch at the output stage is eliminated, which positively affects the system cost and efficiency. A full-design of the circuit and passive components is presented to ensure that the desired pulse specifications are achieved. The proposed approach has been validated using simulation and experimental results. [ABSTRACT FROM AUTHOR]

High-performance buck converters are often required in modern power electronic applications. An augmented buck converter (a main buck converter with augmentation circuits) can achieve fast transient recovery and small output voltage deviation. Compared with other augmentation circuits, a resonant augmentation circuit offers potential electromagnetic interference reduction due to the relatively low $di/dt$ value and compacts the circuit through a reduced inductance for resonance. In this paper, the performance analysis of an augmented buck converter constructed with the resonant circuit are described in detail in terms of voltage-deviation band and power loss. A circuit design and control principle is also proposed for achieving the required voltage deviation for a given transient-detection delay. A 12-to-5-V converter prototype is built to verify the analysis and effectiveness of the proposed methodology. It is demonstrated that the voltage deviation is reduced from 360 to 200 mV using the proposed resonant augmentation circuits and control scheme. The efficiency study shows that the power loss varies from 0.02 to 0.72 W, when the repetition frequency of 5-to-10-A transients changes from 100 to 5 kHz. [ABSTRACT FROM AUTHOR]

Traditional LC resonance circuit can continuously and efficiently accumulate energy from the harvester at optimal impedance matching. Due to electric-field frequency (50 Hz, in China) and small equivalent capacitance (tens or hundreds of picofarads) of electric-field capacitive harvester, it is difficult to manufacture a huge transformer with a large inductance (>10 000 H) to optimally match the capacitive harvester. An upconversion oscillation circuit with a smaller size transformer around high-voltage power line is proposed to achieve efficient electric-field energy harvesting in this paper. The power-frequency output signal is transformed into higher frequency oscillation signal in the upconversion circuit consisting of the switch and the transformer. In this case, optimal impedance matching with the smaller size transformer is realized. Therefore, weak energy from harvester is fast accumulated into the storage capacitor by using the upconversion oscillation circuit. For a 10-kV power line, the upconversion maximum charging power reaches 663 μW in experiment. Due to optimal impedance matching in the upconversion oscillation circuit, the maximum harvesting efficiency is increased from 3% to 90.5%, compared with the traditional harvesting method. While the voltage across the storing capacitor is 3.26 V, the instantaneous discharge circuit can drive a wireless sensor node with an output power of 110 mW. [ABSTRACT FROM AUTHOR]

A convoluted frequency selective surface (FSS) is proposed to provide the unit cell dimension as small as 4.84% of the free space wavelength at resonant frequency. The FSS exhibits high resonant stability for various polarizations and incident angles. Its simple geometry is beneficial for not only easy design but also realizing the single and dual bandpass performances. By introducing an inductance in series connected with the traditional LC parallel resonant circuit, an improved equivalent circuit is established, which can describe the FSS frequency responses more accurately. Furthermore, a set of closed forms related to circuit and dimension parameters are developed. It can serve as the substitute of the full-wave solver to enhance the FSS design efficiency significantly. Finally, a dual bandpass FSS operating at 2.5 and 4.95 GHz was fabricated and measured. The measurement results exhibit satisfactory consistency with the full-wave simulation results. [ABSTRACT FROM AUTHOR]

This paper proposes a single-stage single-switch light-emitting diode (LED) driver that integrates a buck–boost circuit with a Class-E resonant converter by sharing single-switch device. The buck–boost circuit, working as a power-factor correction (PFC) stage, operates in the discontinuous conduction mode (DCM) to shape the input current. The Class-E converter steps down the voltage to drive the LED. For specific component parameters, the Class-E converter can achieve soft-switching on the power switch and two rectifier diodes, and reduce switch losses at high frequencies. Electrolytic capacitors are used in the proposed converter to achieve a lower cost, but the system reliability decreases. To overcome this disadvantage, film capacitors can be used, but the current ripple increases. Neglecting the cost, multilayered film capacitors are the best option, if higher reliability and lower current ripple are required. The proposed driver features high efficiency (90.8%), and a high power factor (PF) (0.995). In this paper, analytical results and design considerations at 100 kHz are presented, and a 100-W prototype with 110 \textV\text{AC} input was built to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

Inductive power transfer (IPT), which employs the principle of electromagnetic induction, is widely applied to wireless charging applications. The efficiency of an IPT system is highly dependent on the quality factor (Q) of the power resonant tank. In this paper, a novel design on the structure of the resonant coil is used in the resonant tank to achieve a significantly high Q above 1000 for the IPT system. Compensating capacitors are used in both primary and secondary circuits to align the resonant frequencies in order for the system resonant status to be maintained by a frequency tracking circuit. The experimental results show that with a primary coil Q of 1200, the proposed IPT system allows power to be transferred at a maximum air gap distance to coil diameter ratio of 1.46 for a highest efficiency of 87% at the resonant frequency of 106 kHz. [ABSTRACT FROM AUTHOR]

A method for designing $LC$ tank circuits to improve energy efficiency and reduce layout area is described. The approach uses a projected shield that is floating, overlaps the trace of the overlying inductor, and adds capacitance to the tank’s inductor. Capacitance is distributed along the spiral traces, and the layout area is thus decreased. In this paper, we investigate the properties of spiral inductors with and without projected shielding, and compare the method with similar circuits including those with floating shields shaped as patterned ground shields. In addition, a measurement methodology for $LC$ tank resonators is developed and presented. Test structures are implemented as microstrip spiral inductors and evaluated as $LC$ tank circuits that resonate between 100 and 500 MHz. The $Q$ values of shielded structures are up to 7% greater than those without shields, and area savings for $LC$ resonators—compared with side-by-side layouts of $L$ and $C$ —are up to 35%. [ABSTRACT FROM PUBLISHER]

This paper proposes an improved half-bridge inverter with wide-input-voltage capability for ozone-driven circuits. The study is motivated because the limited regulation of input voltage often affects the operation flexibility of ozone-driven circuits. Therefore, a modification of a half-bridge inverter along with a multiwinding coil design is proposed in this study, anticipating an increase in the range of input voltage and benefiting the industry applications. To confirm the practicality of this method, a hardware circuit was made with extensive validation. Experimental outcomes support the feasibility of this proposed method for ozone generators, exhibiting a potential of the method extending to other voltage-source applications. [ABSTRACT FROM PUBLISHER]

This paper presents a power converter and its control circuit for high-frequency-fed ac to dc conversion. Based on the resonant technique, the input current is shaped to be sinusoidal and is forced to follow the high-frequency sinusoidal input voltage so as to achieve unity power factor. With the proper selection of the characteristic impedance of the resonant tank, the converter is able to perform the function of a buck, boost, or buck-boost converter. The initial condition of the resonant tank is used to control the output voltage gain of the converter. Since all the switches are operated at the fundamental frequency of the input ac source, the switching loss of the converter is small. A control scheme is also proposed for the converter. A proof-of-concept prototype operating at 400 kHz is constructed and its performance is experimentally measured. Results show that the proposed converter operates as theoretically anticipated. [ABSTRACT FROM AUTHOR]

This paper presents inductive power transfer (IPT) systems for a piezoelectric transformer (PT) based ozone-driven circuit with flexible capacity operation and frequency-tracking mechanism. The proposed system consists of an IPT circuit as the front stage along with an ozone-driven circuit as the back stage. Considering that the ozone generator system was often used under high-humidity and particle-polluted environment, the study hence proposes a contactless power source such that the oxidization and rustiness can be better avoided. Next, by taking the system expansion into consideration, this paper proposes multiple modular parallel PTs in order to increase the output capacity of the designated circuit. This is further followed by a frequency-tracking control developed to promote power delivery efficiency. To confirm this proposed method, the developed system has been realized with hardware circuit validation. Experimental results demonstrate that the proposed system not only delivers the power effectively, but also ensures balanced output current of each PT, thereby facilitating the approach for the ozone-driven applications. [ABSTRACT FROM PUBLISHER]

This paper presents two inductive power transfer (IPT) pickups capable of individually delivering 1.2 kW. The first circuit is a parallel-tuned ac-ac pickup and the second a series-tuned ac-ac pickup. Both circuits regulate the output power by creating a high-frequency ac source in a form suited to various applications requiring a controlled ac output but particularly stage lighting. These circuit topologies build on previous work by significantly improving the loading capability, reducing output noise and harmonic generation, and lowering the required switch ratings. This is achieved through the addition of a second resonant section within each pickup and the relocation of the soft-controlled ac switch. The addition moves the harmonics away from the load path and pickup while still providing full control of the output power. It enables a sinusoidal output waveform with low total harmonic distortion to be created, while placing less stress on the ac switch, which is no longer required to carry the load current. The steady-state operation of both circuits is analyzed herein and circuit waveforms have been verified by experimental results. Both the parallel and series circuits are used to drive a 1.2-kW load with a maximum pickup efficiency of 95% and 94%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of a 40-kV, 20-kJ/s high-voltage capacitor charger based on a series/parallel resonant converter. The inclusion of the parallel resonant capacitor component in this circuit results in the production of a trapezoidal resonant current, which reduces conduction loss. This capacitor is practically realized as a part of the balancing network of the high-voltage rectifiers in the secondary side of the circuit. Particular attention in this paper is paid to the high-voltage transformer, which must be carefully designed to provide the required functionality without negative impact on the resonant circuit. A PSpice simulation has been used to prove that the proposed control method for the circuit is valid. This is supported with the experimental results, which verify that the operation of the circuit is as expected and that the converter is able to meet all the design criteria with an efficiency of up to 96%. [ABSTRACT FROM PUBLISHER]

This paper presents a new model of a finite-difference time-domain (FDTD) cell containing a thin dispersive layer. The model, derived on the basis of an equivalent-circuit approach, is applicable to both normal and tangential electric/magnetic field components. It is shown that such an inhomogeneous FDTD cell can be unequivocally transformed to the homogeneous one, provided that the thin layer is made of single-pole dispersive material. In the case of multi-pole dispersion, field components normal to the layer require approximate treatment, which can be performed with good accuracy if the poles are distant in the frequency domain. The advantage of the proposed method is in the lack of additional computational effort required to solve the scenario containing inhomogeneous electric and/or magnetic dispersive FDTD cells, when compared with their homogeneous counterparts. The solution is successfully validated against both analytical and numerical examples. [ABSTRACT FROM AUTHOR]

Purpose: Numerical study of microwave imaging and microwave-induced thermoacoustic imaging utilizes finite difference time domain (FDTD) analysis for simulation of microwave and acoustic interaction with biological tissues, which is time consuming due to complex grid-segmentation and numerous calculations, not straightforward due to no analytical solution and physical explanation, and incompatible with hardware development requiring circuit simulator such as SPICE. In this paper, instead of conventional FDTD numerical simulation, an equivalent electrical circuit model is proposed to model the microwave acoustic interaction with biological tissues for fast simulation and quantitative analysis in both one and two dimensions (2D). Methods: The equivalent circuit of ideal point-like tissue for microwave-acoustic interaction is proposed including transmission line, voltage-controlled current source, envelop detector, and resistorinductor- capacitor (RLC) network, to model the microwave scattering, thermal expansion, and acoustic generation. Based on which, two-port network of the point-like tissue is built and characterized using pseudo S-parameters and transducer gain. Two dimensional circuit network including acoustic scatterer and acoustic channel is also constructed to model the 2D spatial information and acoustic scattering effect in heterogeneous medium. Results: Both FDTD simulation, circuit simulation, and experimental measurement are performed to compare the results in terms of time domain, frequency domain, and pseudo S-parameters characterization. 2D circuit network simulation is also performed under different scenarios including different sizes of tumors and the effect of acoustic scatterer. Conclusions: The proposed circuit model of microwave acoustic interaction with biological tissue could give good agreement with FDTD simulated and experimental measured results. The pseudo S-parameters and characteristic gain could globally evaluate the performance of tumor detection. The 2D circuit network enables the potential to combine the quasi-numerical simulation and circuit simulation in a uniform simulator for codesign and simulation of a microwave acoustic imaging system, bridging bioeffect study and hardware development seamlessly. [ABSTRACT FROM AUTHOR]

By adding a complex isolation component between two 90^\circ transmission lines at an arbitrary phase angle from the input terminal, a small Wilkinson power divider provides physical separation and electrical isolation between two output ports. General design equations for the complex isolation component are derived from even- and odd-mode analysis. Parallel and series RLC circuits are chosen to realize complex isolation components, respectively. Considering the bandwidths of S22, S33, and S32, inductors in both parallel and series RLC components are omitted to get the widest bandwidths; mathematical proof and design examples are also presented in this paper. A coupled line section with a compensating capacitor is introduced to reduce the circuit size, where characteristic impedances between even and odd mode are different in the coupled line section, and their electrical lengths are also different in inhomogeneous medium. Mathematical equations and simulation examples prove that the compensating capacitor compensates the characteristic impedance difference in the homogeneous medium and the electrical length difference in the inhomogeneous medium. Finally, an experimental circuit shows good agreement with the theoretical simulation. [ABSTRACT FROM AUTHOR]

In order to eliminate the limitation of a narrow frequency range of conventional resonant clocking, intermittent resonant clocking (IRC) is proposed for near/sub-threshold logic circuits. In this paper, IRC is applied to 0.37 V 32-bit adder array with latches and adder array with flip-flops fabricated in a 40 nm CMOS process. Measurement results show that IRC reduces the clock power by 36% at 980 kHz and the clock leakage power by 81% compared with conventional non-resonant clocking when IRC is applied to the adder array with latches. The same power reduction is achieved when IRC is applied to the adder array with flip-flops. IRC can reduce the clock power at any clock frequency, which enables flexible selection of the clock frequency. [ABSTRACT FROM PUBLISHER]

A common-mode (CM) filter based on the LCL filter topology is proposed in this paper, which provides a parallel path for ground currents and which also restricts the magnitude of the EMI noise injected into the grid. The CM filter makes use of the components of a line to line LCL filter, which is modified to address the CM voltage with minimal additional components. This leads to a compact filtering solution. The CM voltage of an adjustable speed drive using a PWM rectifier is analyzed for this purpose. The filter design is based on the CM equivalent circuit of the drive system. The filter addresses the adverse effects of the PWM rectifier in an adjustable speed drive. Guidelines are provided on the selection of the filter components. Different variants of the filter topology are evaluated to establish the effectiveness of the proposed circuit. Experimental results based on EMI measurement on the grid side and the CM current measurement on the motor side are presented. These results validate the effectiveness of the filter. [ABSTRACT FROM AUTHOR]

While teaching network analysis to undergraduate students, the frequency response of electrical circuits consisting of passive elements such as resistors, capacitors and inductors are commonly analysed. Students are familiar with the sharp amplitude peak or trough normally occurring at resonance. This observation is not only intuitively pleasing, but also consistent with the concept of resonance in many physical systems. In the well-known series and parallel RLC circuits, the maximum and minimum currents, respectively, occur at resonance. Because of this, many students and even instructors (sometimes) may erroneously assume that the resonance in general RLC circuits implies maximum or minimum current. In this paper, it will be shown that this is generally untrue. The theoretical analyses and experimental validation of series, parallel and series-parallel RLC circuits are presented to address this common misconception. [ABSTRACT FROM AUTHOR]