Showing papers on "RLC circuit published in 2017"

Topolectrical circuits

Abstract: Invented by Alessandro Volta and F\'elix Savary in the early 19th century, circuits consisting of resistor, inductor and capacitor (RLC) components are omnipresent in modern technology The behavior of an RLC circuit is governed by its circuit Laplacian, which is analogous to the Hamiltonian describing the energetics of a physical system We show that topological semimetal band structures can be realized as admittance bands in a periodic RLC circuit, where we employ the grounding to adjust the spectral position of the bands similar to the chemical potential in a material Topological boundary resonances (TBRs) appear in the impedance read-out of a topolectrical circuit, providing a robust signal for the presence of topological admittance bands For experimental illustration, we build the Su-Schrieffer-Heeger circuit, where our impedance measurement detects a TBR related to the midgap state Due to the versatility of electronic circuits, our topological semimetal construction can be generalized to band structures with arbitrary lattice symmetry Topolectrical circuits establish a bridge between electrical engineering and topological states of matter, where the accessibility, scalability, and operability of electronics synergizes with the intricate boundary properties of topological phases

Quantitative SSR Analysis of Series-Compensated DFIG-Based Wind Farms Using Aggregated RLC Circuit Model

Abstract: A new type of subsynchronous resonance (SSR), namely, subsynchronous control interaction (SSCI), was recently observed in doubly-fed induction generators (DFIGs) interfaced with series-compensated power networks. In this paper, a more accurate method based on aggregated RLC circuit model is proposed to intuitively explain and quantitatively evaluate this type of SSR. For a practical power system containing multiple DFIGs and fixed series compensation, an improved impedance model (IM) is derived, which incorporates DFIG's full-scale control system. Around the series-resonant frequency, IM can be further represented with an aggregated RLC circuit model. Its equivalent parameters are worked out and then used for the quantitative assessment of potential SSR risk. The proposed method is applied for SSR analysis of a practical wind farm system in North China that experienced actual SSR incidents. The consistence between the obtained results and field measured data verifies its effectiveness very well. Further, its advantage in accuracy over existing impedance-based approaches is validated by both eigenvalue analysis and time-domain simulations. The method is also used to quantitatively investigate the impact on SSR stability from the various factors, including wind speed, number of online DFIGs and their control parameters.

A Pole-to-Pole Short-Circuit Fault Current Calculation Method for DC Grids

Abstract: This paper proposes a generic pole-to-pole short-circuit fault current calculation method for dc grids. The calculation procedure begins from the simplified RLC equivalent model of a single modular multilevel converter, and then the prefault matrices and faulted matrices are established and modified to calculate the dc fault currents of all the branches. The proposed approaches are validated by comparing with the electromagnetic transient (EMT) simulation results on PSCAD/EMTDC. Besides, two case studies showed that the calculation method can be easily used to evaluate the severity of a dc fault. Moreover, the calculation can be applied to select the parameters of a fault current limiter (to match the circuit breaker capacity. The main contributions of the proposed numerical calculation method are: 1) The proposed method is accurate and much more time efficient than the EMT simulations; 2) the proposed method can handle all kinds of dc grid networks including the ring, radial, and meshed topologies; and 3) the proposed method is applicable to dc grid with multiple dc voltage level areas connected with dc/dc converters.

Variable Frequency Controller for Inductive Power Transfer in Dynamic Conditions

Abstract: Inductive power transfer is a highly attractive option for powering unmanned aerial or underwater vehicles, in harsh environments and while in continuous motion. This study presents a variable frequency controller for series–series compensated contactless chargers operating in dynamic conditions. The controller tracks, in real time, the frequency for which the output voltage is load independent. The criterion for that is the zeroing of the phase difference between the secondary current and the primary-side inverter output voltage. Control is performed by a phase-locked loop with optical communication between the two sides. Experimental results on a 1-kW prototype, for power transfer while in motion, show fast frequency response, along with steady output voltage, despite load variations. Comparison is performed with two other fixed frequencies of operation; the natural frequency of the primary resonant circuit and the maximum output power frequency at nominal gap. The proposed control is proven superior in terms of output power level and stability, as well as safety to highly misaligned conditions.

A Self-Powered and Optimal SSHI Circuit Integrated With an Active Rectifier for Piezoelectric Energy Harvesting

Abstract: This paper presents a piezoelectric energy harvesting circuit, which integrates a Synchronized Switch Harvesting on Inductor (SSHI) circuit and an active rectifier. The major design challenge of the SSHI method is flipping the capacitor voltage at optimal times. The proposed SSHI circuit inserts an active diode on each resonant loop, which ensures flipping of the capacitor voltage at optimal times and eliminates the need to tune the switching time. The diodes of the SSHI circuit are also used as a rectifier to further simplify the controller. The key advantage of the proposed circuit is a simple controller, which leads to low power dissipation of the proposed circuit to result in high efficiency. The proposed circuit is self-powered and capable of starting even when the battery is completely drained. The circuit was fabricated in BiCMOS $0.25~\mu \text {m}$ technology with a die size of $0.98 \times 0.76$ mm2. Measured results indicate that the proposed circuit increases the amount of power harvested from a piezoelectric cantilever by 2.1 times when compared with a full bridge (FB) rectifier and achieves a power conversion efficiency of 85%. The proposed circuit dissipates about $24~\mu \text {W}$ while the controller alone only $1.5~\mu \text {W}$ .

An Inductorless Bias-Flip Rectifier for Piezoelectric Energy Harvesting

Abstract: Piezoelectric vibration energy harvesters have drawn much interest for powering self-sustained electronic devices. Furthermore, the continuous push toward miniaturization and higher levels of integration continues to form key drivers for autonomous sensor systems being developed as parts of the emerging Internet of Things (IoT) paradigm. The synchronized switch harvesting (SSH) on inductor and synchronous electrical charge extraction are two of the most efficient interface circuits for piezoelectric energy harvesters; however, inductors are indispensable components in these interfaces. The required inductor values can be up to 10 mH to achieve high efficiencies, which significantly increase overall system volume, counter to the requirement for miniaturized self-power systems for IoT. An inductorless bias-flip rectifier is proposed in this paper to perform residual charge inversion using capacitors instead of inductors. The voltage flip efficiency goes up to 80% while eight switched capacitors are employed. The proposed SSH on capacitors circuit is designed and fabricated in a 0.35- $\mu \text{m}$ CMOS process. The performance is experimentally measured and it shows a 9.7 $\times $ performance improvement compared with a full-bridge rectifier for the case of a 2.5-V open-circuit zero-peak voltage amplitude generated by the piezoelectric harvester. This performance improvement is higher than most of the reported state-of-the-art inductor-based interface circuits, while the proposed circuit has a significantly smaller overall volume enabling system miniaturization.

Single-switch high step-up converter based on coupled inductor and switched capacitor techniques with quasi-resonant operation

Abstract: This study presents a novel single-switch high step-up dc-dc converter employing a quasi-resonant operation with high efficiency and low ripple continuous input current characteristics. In order to achieve a high voltage gain, a combination of coupled inductor and switched capacitor techniques is used in the proposed dc-dc converter. Moreover, utilising a series resonance capacitor with the leakage inductance of the coupled inductor leads to a resonant circuit. Subsequently, by employing a quasi-resonant operation, the switching loss of the proposed dc-dc converter has been reduced significantly. Operational analysis, mathematical derivation, component voltage and current ratings are well demonstrated in this study. Finally, the performance of the proposed circuit is evaluated through a 200 W laboratory prototype with 25 V input voltage and 400 V output voltage. The maximum efficiency achieved at full load is 96.4%.

Implementation of a 3.3-kW DC–DC Converter for EV On-Board Charger Employing the Series-Resonant Converter With Reduced-Frequency-Range Control

Abstract: A control method that improves performance of series-resonant converters that operate with a wide input voltage and/or output voltage range by substantially reducing their switching frequency range is introduced. The switching-frequency-range reduction is achieved by controlling the output voltage with a combination of variable-frequency and delay-time control. Variable-frequency control is employed to control the primary switches, while delay-time control is used to control secondary-side rectifier switches provided in place of diode rectifiers. A series-resonant converter with the proposed control method is employed as the output stage of the on-board charger module that operates with a wide battery-voltage range. By substantially reducing the switching frequency range, the overall operating frequency is increased to reduce the sizes of the passive components, and hence, increase power density. The performance evaluation of the proposed series-resonant converter with delay-time control was done on a 3.3-kW prototype delivering energy from 400-V bus, which is the output of the power factor correction front end, to a battery operating with voltage range between 180 and 430 V. Two implementations of the prototype circuit, one employing gallium nitride (GaN) and the other employing silicon (Si) switches, were evaluated and compared. The prototype with Si switches that at full load over the entire output voltage range operates with a switching frequency variation from approximately 150 to 190 kHz exhibits the maximum full-load efficiency of 98.1%, whereas the corresponding frequency range and efficiency of the prototype with GaN devices are 145–190 kHz and 97.4%, respectively.

Capacitive Power Transfer System With a Mixed-Resonant Topology for Constant-Current Multiple-Pickup Applications

Abstract: Capacitive power transfer (CPT) systems based on high-frequency electric field coupling have attracted much attention recently due to their simplicity and low eddy-current losses. This paper proposes a mixed-resonant topology consisted of a Π- CLC resonant circuit on the primary side and a T- CLC circuit on the secondary side for multiple pickups constant current output applications. The voltage gain, current gain, and zero phase angle frequency at different operating modes of Π- CLC and T- CLC circuits are analyzed by fundamental frequency approximation, and the conditions leading to a constant output current independent of loads are determined. Based on the analysis, a design method to determine the resonant network parameters is proposed according to the required output current of each pickup. A prototype with three pickups has been designed and built, and both simulation and experimental results have demonstrated that the proposed multiple-pickup CPT system can output a constant current at each operating power pickup against the load variations of itself and others.

A Wireless Passive Pressure and Temperature Sensor via a Dual LC Resonant Circuit in Harsh Environments

Abstract: This paper presents a passive wireless sensor for simultaneously and remotely measuring pressure and temperature under harsh environments. The sensor consists of a dual $LC$ (inductor and capacitor) resonant circuit, one without a cavity and the other with a cavity capacitor for temperature and pressure sensing, respectively. The low-temperature co-fired ceramic technology is used to fabricate the sensor, making it suitable for high-temperature harsh environment operations. Experimental results show the prototype sensor has temperature sensitivity of 8.15 kHz/°C and pressure sensitivity of 1.96 MHz/Bar up to 400°C. [2016-0157]

Non-Autonomous Second-Order Memristive Chaotic Circuit

Abstract: A non-autonomous second-order memristive chaotic circuit is considered in this paper, which is comparatively simple, only consisting of a memristor, a capacitor, a resistor, and a sinusoidal voltage source. Based on the descriptive equation of the memristive circuit, the dynamical behaviors are investigated by theoretical analyses and numerical simulations. It is noted that the number of AC equilibrium points changes with the evolution of the time and the circuit exhibits striking dynamical features, including period, chaos, forward period-doubling, reverse period-doubling, tangent bifurcation, and crisis scenarios. Furthermore, a hardware circuit is set up by off-the-shelf discrete components, where hardware experiments are performed to verify the numerical results. The most significant feature of the proposed memristive circuit is the inductor-free realization with simplified topology, which makes the circuit much simpler and more intuitive in physical realization.

Passive Realization of Fractional-Order Impedances by a Fractional Element and RLC Components: Conditions and Procedure

Abstract: In this paper, conditions for checking the realizability of fractional-order impedance functions by passive networks composed of a fractional element (either a fractional capacitor or a fractional inductor) and some RLC components are derived To this end, at first the newly obtained conditions for realizability of fractional-order impedance functions by a passive network composed of a fractional capacitor and some RLC components are extended to include the case that the polynomials involving in the impedance function can have roots on the imaginary axis Then, the necessary and sufficient conditions are found on a fractional-order impedance function to be realized by a passive network composed of a fractional element and some RLC components Furthermore, a procedure for finding the realization in the realizable cases is proposed Finally, the realizability conditions for a special class of fractional-order impedance functions are simplified

Properties and physical interpretation of the dynamic interactions between voltage source converters and grid: electrical oscillation and its stability control

Abstract: Voltage source converters (VSCs) play an important role in the power conversion of renewable power generation (RPG) systems. Conventional power systems are considerably affected by power electronic devices in systems with a high percentage of RPG. Various abnormal interactions in the form of oscillations between VSCs and grid have been reported, whereas the mechanism at the core is still lacking understanding. In this study, the properties of interactions between the VSC and grid are investigated, and through an analytical model the mechanisms of electrical oscillations are revealed. First, a simple resistance-inductance-capacitance (RLC) equivalent to the small-signal model of VSC-grid system was derived based on the knowledge of virtual passive element effects of VSC. Then, an intrinsic oscillatory point in the RLC circuit was identified, the damping characteristics of the current controller and phase-locked-loop (PLL) at this point were analysed. Subsequently, a critical stability criterion for the determination of PLL bandwidth that may trigger oscillations was established. For the improvement of the overall damping, a VSC stabiliser was proposed. Finally, the mechanism analysis and analytical criteria were verified by time-domain simulations in PSCAD/EMTDC.

High step-up DC–DC converter with switched-capacitor and its zero-voltage switching realisation

Abstract: As generally acknowledged, the high step-up DC–DC converter is widely used in the sustainable energy system as the front-end stage of the DC–AC converter. Therefore, a novel high step-up DC–DC converter is proposed in this study. The proposed converter with network of switched-inductor and switched-capacitor can achieve high voltage gain under low duty cycle. Meanwhile, the active switches and diodes suffer from low voltage stress. More importantly, an auxiliary resonant circuit with lower losses and cost is employed to realise zero-voltage switching (ZVS) turned-on and ZVS turned-off for the active switches, resulting in high conversion efficiency. Firstly, the operation principle and steady-state performance are discussed in detail. Then, prototype with power rating of 200 W is built to verify the performance of the proposed converter. The maximum efficiency of the prototype can be up to 96%, and the experimental results agree with the theoretical analysis and the simulation results well.

A Step-Up Transformerless, ZV–ZCS High-Gain DC/DC Converter With Output Voltage Regulation Using Modular Step-Up Resonant Cells for DC Grid in Wind Systems

Abstract: The use of medium voltage dc (MVDC) grid in offshore wind farms has been presented as an alternative solution to eliminate the conventional bulky low frequency step-up transformers used in the medium voltage ac grid. In order to reduce the transmission losses, the trend is to increase the wind turbine output voltage to at least thousands of volts. In this paper, a variable frequency controlled MVDC converter with modular approach of combining multiple step-up resonant circuits and multistring of switches configuration is proposed for MVDC grid. The proposed converter has the following features: 1) the multistring arrangement of the switches allows much lower voltage stress across each transistor; 2) the modular step-up resonant circuits are able to achieve high voltage gain so that transformer with large turns ratio is not required; 3) zero voltage switching turn-on and zero current switching turn-off are achieved in all the switches; 4) the output MVDC level is controlled by variable frequency control of the step-up converter; and 5) circulating energy in all the resonant circuit modules is minimized through close-to-resonant operation for different load conditions. Simulation results are provided on a 4 kVac/50 kV, 2 MW converter for a wide range of load conditions. Experimental results are provided on a laboratory-scale 200 V/1.6 kV proof-of-concept prototype to highlight the merits of this paper.

Windowed SHE-PWM of Interleaved Four-Quadrant Converters for Resonance Suppression in Traction Power Supply Systems

Abstract: AC electric locomotives that use a number of interleaved four-quadrant converters generate high-frequency switching harmonics which may stimulate certain resonances in traction power supply systems (TPSSs). A windowed selective harmonic elimination pulse-width modulation (SHE-PWM) method is proposed to suppress such resonances. Owing to the windowed design and the precalculated solutions, the proposed method covers the wide potential resonant frequency range and addresses the resonant frequency variation while keeping the low switching frequency of the traction converters. The proposed windowed SHE-PWM is fully tested with a closed-loop controller in a simulation model with the TPSS and the ac electric locomotive. Comparative simulation results show that the windowed SHE-PWM is an effective alternative that overcomes the resonance suppression limitations of the conventional phase-shifted PWM (PS-PWM). The performance of proposed windowed SHE-PWM on an experimental equivalent resonant circuit is further evaluated and compared with PS-PWM. Both simulation and experimental results verify the effectiveness and feasibility of the proposed method.

A Sensitivity-Improved PFM LLC Resonant Full-Bridge DC–DC Converter With LC Antiresonant Circuitry

Abstract: An LLC resonant circuit-based full-bridge dc–dc converter with an LC antiresonant tank for improving the performance of pulse frequency modulation (PFM) is proposed in this paper. The proposed resonant dc–dc converter, named as LLC-LC converter, can extend a voltage regulation area below the unity gain with a smaller frequency variation of PFM by the effect of the antiresonant tank. This advantageous property contributes for protecting overcurrent in the case of the short-circuit load condition as well as the start-up interval in the designed band of switching frequency. The circuit topology and operating principle of the proposed converter is described, after which the design procedure of the operating frequency and circuit parameters is presented. The performances on the soft switching and the steady-state PFM characteristics of the LLC-LC converter are evaluated under the open-loop control in experiment of a 2.5-kW prototype, and its actual efficiency is compared with an LLC converter prototype. For revealing the effectiveness of the LLC-LC resonant circuitry, voltages and currents of the series and antiresonant tanks are analyzed, respectively, with state-plane trajectories based on calculation and experiment, whereby the power and energy of each resonant tank are demonstrated. Finally, the feasibility of the proposed converter is evaluated from the practical point of view.

New Resonant Gate Driver Circuit for High-Frequency Application of Silicon Carbide MOSFETs

Abstract: Silicon carbide (SiC) and gallium nitride metal–oxide–semiconductor field-effect transistors (MOSFETs) are capable of processing high power at high switching frequencies with less switching losses and conduction losses. The gate driver circuit power consumption is directly proportional to the switching frequency. The power taken from the gate supply is dissipated in the gate resistance of the conventional gate driver (CGD) circuit. Instead of dissipating all the gate driver energy, some energy can be recovered or recycled by utilizing the principle of resonance. This reduces the net power being taken from the gate supply. This paper presents a new resonant gate driver (RGD) circuit which consumes less power compared to the CGD circuit at high switching frequencies. The proposed gate driver is designed for SiC MOSFETs. It can be modified appropriately to suit for insulated-gate bipolar transistors and other MOSFETs also. The performance of the proposed circuit is simulated in LTSpice environment, and an experimental prototype of the proposed circuit is developed to validate its performance. The proposed RGD circuit has achieved nearly 50% reduction in gate driver power consumption compared to the CGD circuit.

Medium frequency transformer leakage inductance modeling and experimental verification

Abstract: This paper provides detailed analytical modeling and finite elements method (FEM) analysis of the medium frequency transformer (MFT) leakage inductance, as one of the key design factors governing the operation of galvanically isolated power electronics converters. Precise leakage inductance modeling in design stage is especially important for converter topologies based on resonant conversion where MFT is a part of a resonant circuit. A comprehensive analytical model that takes into account both the geometric and frequency effects on the given MFT leakage inductance is generated based on the transformer physical structure, thus allowing for optimization of the MFT design with targeted equivalent circuit leakage inductance reference. The derived models are benchmarked to the measurement results on the developed MFT prototype.

Comparative evaluation of IPT resonant circuit topologies for wireless power supplies of implantable mechanical circulatory support systems

Abstract: Today's implantable blood pumps, such as Left Ventricular Assist Devices (LVAD) are powered by means of a percutaneous driveline, which constitutes a severe risk of infection to the patient Inductive Power Transfer (IPT) technology offers a solution to replace the driveline by a wireless energy link In this paper, three commonly used IPT resonant circuit topologies are compared regarding power transfer efficiency and heating of the tissue In the course of the analysis, the main advantages and disadvantages of each topology are identified and as a result it was found that regarding the heating of the tissue, the series-series compensated topology is the most promising solution for Transcutaneous Energy Transfer (TET) systems capable to provide a peak power transmission of up to 30 W Operated at the resonant frequency using an efficiency optimal control, the series-series compensation topology achieves the highest DC-to-DC power conversion efficiency in the coil coupling and output power range, but requires a higher complexity of the control system, and more important, it shows an increasing secondary side coil power loss with decreasing coil coupling factor In contrast, the operation near the frequency for load independent voltage gain using a load impedance control technique achieves similar power conversion efficiencies at high coil coupling factors, but offers a lower complexity of the overall TET system The peak DC-to-DC efficiency measured with a hardware prototype is 97 % at a coil separation distance of 10 mm, a primary and secondary coil diameter of 70 mm and ideal coil alignment Even at a coil separation distance of 20 mm and an output power of 5W, the efficiency is 905 %

Stability of Markov jump systems with quadratic terms and its application to RLC circuits

Abstract: The paper presents results for the second moment stability of continuous-time Markov jump systems with quadratic terms, aiming for engineering applications. Quadratic terms stem from physical constraints in applications, as in electronic circuits based on resistor (R), inductor (L), and capacitor (C). In the paper, an RLC circuit supplied a load driven by jumps produced by a Markov chain—the RLC circuit used sensors that measured the quadratic of electrical currents and voltages. Our result was then used to design a stabilizing controller for the RLC circuit with measurements based on that quadratic terms. The experimental data confirm the usefulness of our approach.

Analytical Models of High-Speed RLC Interconnect Delay for Complex and Real Poles

Abstract: Continuous shrinking of the size of CMOS technology leads to extremely fast devices, but the resulting interconnect structures impose so many parasitic effects that the advantage of extremely scaled and ultrahigh-speed transistors would be completely overshadowed if appropriate remedial steps are not taken. This requires an accurate and efficient estimation of interconnect parasitics and analysis of their impact on integrated circuit performance. This paper proposes a new delay model for RLC interconnect networks in CMOS technology based on a second order approximate transfer function. The proposed modeling approach includes all possible scenarios (complex poles, real poles, and double poles) in the interconnect model. Simulation results show that the proposed delay model is almost independent of the ratio of ${V}_{\mathrm { {out}}} / V_{\mathrm { {in}}}$ , and the driver resistance has significant impact on the delay. The simulation results also show that the real pole model provides better accuracy and is much faster than the complex pole model. This observation would help to optimize the values of interconnect parasitics for faster operation.

Coilgun Velocity Optimization With Current Switch Circuit

Abstract: 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.

Minimum passive components based lossy and lossless inductor simulators employing a new active block

Abstract: In this paper a new active element namely Dual X current conveyor differential input transconductance amplifier (DXCCDITA) is proposed. The DXCCDITA is utilized in designing eight topologies of lossy and lossless grounded inductor simulators and two topologies of floating inductor simulators. All the designed grounded simulators require only two passive elements and a single active block. The two floating inductor simulators require a single active block and one or three grounded passive elements. In addition, all the designs make use of only grounded capacitors for implementation which is advantageous for fabrication. All the proposed active inductors, except two, did not require any component matching conditions for realization and all the inductor simulators are perfectly tunable. The effect of non-idealities on the proposed grounded simulator structures is also studied. To demonstrate the workability of the inductor simulators they are used in design of second order low pass filter, parallel RLC resonance circuit, third order Butterworth high pass filter, parallel RLC current mode multifunction filter and a voltage mode band pass filter. The DXCCDITA is implemented in 0.35 μm TSMC CMOS technology parameters and tested in Tanner EDA. Sufficient number of simulations are provided to establish the functionality of the active inductor structures.

Analysis and Optimization of Switched Capacitor Power Conversion Circuits With Parasitic Resistances and Inductances

Abstract: For a switched-capacitor converter (SCC) built by discrete components, its performance is inevitably influenced by parasitic resistances and stray inductances. A basic SCC unit including parasitic resistances and stray inductances behaves as an RLC series circuit operated in charging and discharging states alternatively. Hard-switching SCC with small Q factor, due to the small stray inductance, is analyzed based on overdamping RLC circuit theory. And the underdamping RLC series network is used to analyze soft-switching SCC whose Q factor is greater than 0.5. New mathematical equations are derived to evaluate the impact of parasitic resistances and inductances on the performance of SCCs. Following that, the corresponding design methodologies are proposed for both hard- and soft-switching SCCs. The effectiveness of the proposed analysis and design methods are experimentally demonstrated by a 300-W double-mode SCC prototype.

A fractional-order multifunctional n -step honeycomb RLC circuit network

Abstract: We investigate a multifunctional n-step honeycomb network which has not been studied before. By adjusting the circuit parameters, such a network can be transformed into several different networks with a variety of functions, such as a regular ladder network and a triangular network. We derive two new formulae for equivalent resistance in the resistor network and equivalent impedance in the LC network, which are in the fractional-order domain. First, we simplify the complex network into a simple equivalent model. Second, using Kirchhoff’s laws, we establish a fractional difference equation. Third, we construct an equivalent transformation method to obtain a general solution for the nonlinear differential equation. In practical applications, several interesting special results are obtained. In particular, an n-step impedance LC network is discussed and many new characteristics of complex impedance have been found.

Wideband Matching of Full-Wavelength Dipole With Reflector for Base Station

Abstract: This communication introduces a wideband hybrid feeding method for full-wavelength dipole antennas with a reflector. A full-wavelength dipole is designed to cover the band from 698 to 960 MHz for cellular base station applications. Its matching circuit consists of a triple-tuned circuit and a quasi-quarter-wavelength impedance transformer. The proposed matching circuit can provide balanced feeding as a balun and has a compact size. The working mechanism and a complete design scheme of the proposed matching circuit are elaborated. The matching circuit is designed and optimized using a circuit theory model and then physically realized using microstrip lines based on full-wave simulation. The measured reflection coefficient $|S_{11}|$ is lesser than −14 dB across the entire band from 698 to 960 MHz, exhibiting a bandwidth of 32%. This is the first time that a wideband center-fed full-wavelength dipole is proposed.

A single-wire capacitive power transfer system with large coupling alignment tolerance

Abstract: This paper introduces a new Wireless Power Transfer (WPT) system based on single pair of electric field coupling without a current return path. Such a single-contact Capacitive Power Transfer (CPT) system helps to enhance the coupling tolerance between the coupled plates. A class E converter is designed to drive an LCLC resonant circuit to boost the voltage at the primary side of the coupling plate, while a CLCL resonant circuit is used to boost the output current to the load. A practical prototype is built, and it has demonstrated that 3.8 W of power can be transferred across a single pair of copper coupling plates (100mm ×100mm) at full alignment. And it has found that the single-wire CPT system has a large coupling tolerance against both lateral and angular misalignments between the coupled plates.

Time domain analysis of LLC resonant converters in the boost mode for battery charger applications

Abstract: In order to support different types of rechargeable batteries (e.g. Li-Ion, Lead-Acid, NiMh), the design of universal battery chargers must focus on wide output voltage regulation, rather than on constant voltage regulation. The universal battery charger is expected to provide a demanding output voltage range between nominal and 1.5 times nominal, while sustaining the maximum power delivery and maintaining high efficiency. The softly switched LLC resonant converter is one of the best topologies for designing battery chargers due to its ability to produce variable voltage gains in different operating frequencies, while providing soft switching for all semiconductor devices. The objective of this paper is to solve the Time Domain set equations of the LLC resonant converter in boost mode, and extract closed form answer for the voltage gain as a function of converter variables (e.g. input voltage, switching frequency, resonant elements, output load). The closed form answer can precisely predict the behavior of the LLC resonant converter and can be employed in order to design and optimize the LLC resonant converter in the boost mode. In this paper, the Time Domain (TD) analysis of the LLC resonant converter in the operating mode below the resonant frequency will be presented, and a closed form answer for the converter voltage gain will be extracted. The experimental results, extracted from a 1200W platform, shows that using the obtained voltage gain equation for the LLC resonant converter results in a far higher degree of accuracy than does using First Harmonic Approximation method.

High Accuracy Knee Voltage Detection for Primary-Side Control in Flyback Battery Charger

Abstract: In a primary-side control flyback charger, the accuracy of a conventional knee voltage detection (KVD) approach to obtain the output voltage is influenced by the inclusion of a snubber circuit. Although the snubber circuit dampens the ringing voltages due to switching, it also affect the resonance frequency which would reduce the timing of the sampling circuit, resulting in the inaccurate sampling of output voltage. By analyzing the snubber circuit and its resonance on the primary side, this paper implements a proposed accuracy knee voltage detection (AKVD) technique to compensate for the induced resonance frequency. Furthermore, the proposed constant current (CC) regulator ensures the accuracy of CC mode by compensating the sensing current error caused by the switching delay of the power transistor. A prototype consisting of a test chip fabricated with a $0.5\mu \text {m}$ BCD process demonstrates a voltage accuracy exceeding 99.63%. This is achieved by mitigating abnormal detections and thus ensuring correct control of charging current throughout the charging period.