Showing papers on "RLC circuit published in 2015"
TL;DR: A new active cellbalancing method for Li-ion batteries that uses an LC series resonant circuit as an energy carrier, which transfers the balancing energy directly from the highest charged cell to the lowest charged cell.
Abstract: This paper proposes a new active cell-balancing method for Li-ion batteries. It uses an $LC$ series resonant circuit as an energy carrier, which transfers the balancing energy directly from the highest charged cell to the lowest charged cell. The method requires $N+5$ bilateral switches and one $LC$ resonant circuit, where $N$ is the number of cells in the string of batteries. The balancing speed is improved by allowing energy transfer between any two cells in the battery string, and power consumption for balancing is reduced by operating all switches in the circuit at a zero-current switching condition. An experimental cell-balancing circuit for a 12-cell Li-ion battery string shows that fast and transformerless balancing is possible using the proposed method. Measured power transfer efficiencies were 93.2% and 78.9% at balancing powers of 0.56 and 1.94 W, respectively.
146 citations
TL;DR: In this article, a current-fed LLC resonant converter that is able to achieve high efficiency over a wide input voltage range is derived by integrating a two-phase interleaved boost circuit and a full-bridge LLC circuit together by virtue of sharing the same fullbridge switching unit.
Abstract: This paper proposes a current-fed LLC resonant converter that is able to achieve high efficiency over a wide input voltage range. It is derived by integrating a two-phase interleaved boost circuit and a full-bridge LLC circuit together by virtue of sharing the same full-bridge switching unit. Compared with conventional full-bridge LLC converter, the gain characteristic is improved in terms of both gain range and optimal operation area, fixed-frequency pulsewidth-modulated (PWM) control is employed to achieve output voltage regulation, and the input current ripple is minimized as well. The voltage across the turned-off primary-side switch can be always clamped by the bus voltage, reducing the switch voltage stress. Besides, its other distinct features, such as single-stage configuration, and soft switching for all switches also contribute to high power conversion efficiency. The operation principles are presented, and then the main characteristics regarding gain, input current ripple, and zero-voltage switching (ZVS) considering the nonlinear output capacitance of MOSFET are investigated and compared with conventional solutions. Also, the design procedure for some key parameters is presented, and two kinds of interleaved boost integrated resonant converter topologies are generalized. Finally, experimental results of a converter prototype with 120–240 V input and 24 V/25 A output verify all considerations.
140 citations
TL;DR: In this paper, an equivalent circuit model of an ultra-thin metamaterial absorber comprising a square-ring-shaped frequency selective surface (FSS) is presented, and the effects of substrate thickness and dielectric permittivity variation on the lumped parameters and full width at half-maximum (FWHM) bandwidth are investigated.
Abstract: An equivalent circuit model of an ultra-thin metamaterial absorber comprising a square-ring-shaped frequency selective surface (FSS) is presented. The model can be considered as series $RLC$ resonators connected in parallel with coupling capacitance and short-circuited transmission line. The even- and odd-mode couplings have been incorporated to accurately determine the lumped parameters as well as the absorption frequency of the absorber structure. The effects of substrate thickness and dielectric permittivity variation on the lumped parameters and full width at half-maximum (FWHM) bandwidth are investigated based on the proposed model. The absorber has been fabricated, and close matching among the calculated, simulated, and measured results has been observed.
139 citations
TL;DR: Because the input voltage of the LED driver is divided by two capacitors, the bus voltage is considerably reduced to almost the input peak voltage, rendering the novel single-stage LED driver to work suitably under high-input-voltage conditions.
Abstract: In this paper, a single-stage LED driver is proposed for a street lighting system. Two boost circuits that share a single inductor are formed by integrating the switches of a half-bridge $LLC$ resonant converter. Both boost circuits operate in the boundary conduction mode, which realizes a power-factor correction function. Because the input voltage of the LED driver is divided by two capacitors, the bus voltage is considerably reduced to almost the input peak voltage, rendering the novel single-stage LED driver to work suitably under high-input-voltage conditions. The soft-switching characteristics of the half-bridge $LLC$ resonant circuit are not affected by the integration of the switches; thus, the converter has a low cost and a high efficiency. A 100-W prototype was developed, and the efficiency was determined to be as high as 91.1% in a full-load state under a 220-V ac input.
118 citations
TL;DR: Screen-printed inductors, capacitors, resistors and an RLC circuit on flexible plastic substrates are presented and the design process for minimization of inductor series resistance that enables their use in power electronics is reported on.
Abstract: Additive and low-temperature printing processes enable the integration of diverse electronic devices, both power-supplying and power-consuming, on flexible substrates at low cost. Production of a complete electronic system from these devices, however, often requires power electronics to convert between the various operating voltages of the devices. Passive components-inductors, capacitors, and resistors-perform functions such as filtering, short-term energy storage, and voltage measurement, which are vital in power electronics and many other applications. In this paper, we present screen-printed inductors, capacitors, resistors and an RLC circuit on flexible plastic substrates, and report on the design process for minimization of inductor series resistance that enables their use in power electronics. Printed inductors and resistors are then incorporated into a step-up voltage regulator circuit. Organic light-emitting diodes and a flexible lithium ion battery are fabricated and the voltage regulator is used to power the diodes from the battery, demonstrating the potential of printed passive components to replace conventional surface-mount components in a DC-DC converter application.
104 citations
TL;DR: In this article, a single-stage LED driver based on an interleaved buck-boost circuit and an LLC resonant converter is proposed, which can decrease the system cost and improve the system efficiency.
Abstract: A single-stage LED driver based on an interleaved buck–boost circuit and an LLC resonant converter is proposed. The buck–boost circuit and the LLC resonant converter are integrated by sharing switches, which can decrease the system cost and improve the system efficiency. The input voltage of the buck–boost circuit is half of the rectified voltage, and two buck–boost circuits are formed with the two half-bridge switches and corresponding diodes. The two buck–boost circuits work in interleaved mode and the inductor current is in discontinuous conduction mode, both helping to achieve the power factor (PF) correction. A half-bridge LLC resonant converter is adopted here, and the soft switching characteristic of the LLC resonant converter is not changed by the switch integration. The primary-side switches still work in zero voltage switching (ZVS) mode, and the secondary diodes still work in ZCS mode, which both reduce the switching losses and improve the efficiency of the system. The design process is described in detail this paper, and a 100-W LED street lighting prototype is proposed, with a PF of 0.995, a total harmonic distortion of 5.7%, and an efficiency of 91.6% at full load.
76 citations
TL;DR: In this paper, the stored energy of an antenna is defined from the difference between the energy density and the far field energy for many but not all cases, and the results indicate that stored energy in the fields, currents, and circuit models agree well for small antennas.
Abstract: Although the stored energy of an antenna is instrumental in the evaluation of antenna Q and the associated physical bounds, it is difficult to strictly define stored energy. Classically, the stored energy is either determined from the input impedance of the antenna or the electromagnetic fields around the antenna. The new energy expressions proposed by Vandenbosch express the stored energy in the current densities in the antenna structure. These expressions are equal to the stored energy defined from the difference between the energy density and the far field energy for many but not all cases. Here, the different approaches to determine the stored energy are compared for dipole, loop, inverted L-antennas, and bow-tie antennas. We use Brune synthesized circuit models to determine the stored energy from the input impedance. We also compare the results with differentiation of the input impedance and the obtained bandwidth. The results indicate that the stored energy in the fields, currents, and circuit models agree well for small antennas. For higher frequencies, the stored energy expressed in the currents agrees with the stored energy determined from Brune synthesized circuit models whereas the stored energy approximated by differentiation of input impedance gives a lower value for some cases. The corresponding results for the bandwidth suggest that the inverse proportionality between the fractional bandwidth and Q-factor depends on the threshold level of the reflection coefficient.
76 citations
TL;DR: In this article, the authors proposed a current-source-output LED driver based on LCLC resonant circuit to provide a constant output current regardless of variations in LED parameters, where the number of additional capacitors is scalable with number of LED strings for current balancing.
Abstract: Passive or active current balancing circuits are usually used to mitigate current imbalance in driving multiple light-emitting-diode (LED) strings. Passive current balancing schemes adopting capacitors with high reliability, small size and low cost are very popular in many applications. However, the high reactive power of the capacitive balancing scheme with variable frequency control will bring high power stress on the VA rating of the main switches which drive this passive current balancing circuit and decrease the overall efficiency. Fixed frequency control does not permit zero-voltage switching (ZVS) under load variations. Hence, this paper proposes a current-source-output LED driver based on LCLC resonant circuit to provide a constant output current regardless of variations in LED parameters. In the LCLC circuit, the number of additional capacitors is scalable with the number of LED strings for current balancing. Moreover, the input impedance of the improved LCLC circuit is designed to be resistive at the operating frequency to minimize reactive power. The conventional duty cycle control can easily incorporate ZVS. The analysis, implementation and verification are detailed in this paper.
74 citations
TL;DR: A combination of IMPS and mNIRS can compensate for the glucose estimation error to improve its accuracy and an artificial neural network in external DSP is proposed to reduce the mean absolute relative difference.
Abstract: A multi-modal spectroscopy IC combining impedance spectroscopy (IMPS) and multi-wavelength near-infrared spectroscopy (mNIRS) is proposed for high precision non-invasive glucose level estimation. A combination of IMPS and mNIRS can compensate for the glucose estimation error to improve its accuracy. The IMPS circuit measures dielectric characteristics of the tissue using the RLC resonant frequency and the resonant impedance to estimate the glucose level. To accurately find resonant frequency, a 2-step frequency sweep sinusoidal oscillator (FSSO) is proposed: 1) 8-level coarse frequency switching (f STEP = 9.4 kHz) in 10–76 kHz, and 2) fine analog frequency sweep in the range of 18.9 kHz. During the frequency sweep, the adaptive gain control loop stabilizes the output voltage swing (400 mV p-p ). To improve accuracy of mNIRS, three wavelengths, 850 nm, 950 nm, and 1,300 nm, are used. For highly accurate glucose estimation, the measurement data of the IMPS and mNIRS are combined by an artificial neural network (ANN) in external DSP. The proposed ANN method reduces the mean absolute relative difference to 8.3% from 15% of IMPS, and 15–20% of mNIRS in 80–180 mg/dL blood glucose level. The proposed multi-modal spectroscopy IC occupies 12.5 mm 2 in a 0.18 µm 1P6M CMOS technology and dissipates a peak power of 38 mW with the maximum radiant emitting power of 12.1 mW.
72 citations
TL;DR: In this paper, the authors proposed a new interleaved current-fed resonant converter with significantly reduced high current side output filter, which has theoretically zero output filter capacitance, low-input current ripple, ZCS turn-on and turnoff for all switches and diodes, and zero di/dt at turn-off of Diodes when operated at load independent points.
Abstract: This paper proposes a new interleaved current-fed resonant converter with significantly reduced high current side output filter. The proposed interleaved converter has theoretically zero output filter capacitance, low-input current ripple, ZCS turn-on and turn-off for all switches and diodes, and zero di/dt at turn-off of diodes when operated at load independent points. A two-stage power conversion technique is applied to the interleaved converter for high efficiency under wide voltage range operation. A 2-kW prototype of the proposed low-voltage dc/dc converter for EV and HEV applications is built and tested to verify the validity of the proposed operation.
61 citations
TL;DR: In this paper, a novel design on the structure of the resonant coil is used in the IPT system to achieve a significantly high quality factor (Q) above 1000 for IPT systems.
Abstract: 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.
TL;DR: In this article, an integrated wireless passive sensor for remotely monitoring both temperature and relative humidity is presented, which consists of a coil and a capacitor to form an inductor-capacitor ( $LC$ ) resonant circuit, which oscillates electrically at its resonant frequency.
Abstract: This paper presents an integrated wireless passive sensor for remotely monitoring both temperature and relative humidity. The sensor consists of a coil and a capacitor to form an inductor–capacitor ( $LC$ ) resonant circuit, which oscillates electrically at its resonant frequency. The inductor was a single-layer planar spiral copper inductor and the capacitor was fabricated by the silicon-on-glass process, which utilizes graphene oxide films as the sensing material. The change of the capacitance due to environmental humidity variation shifts the resonant frequency, while environmental temperature affects the resistance and capacitance of the $LC$ circuit and changes the resonant frequency and quality factor. By monitoring the real portion magnitude maximum of the impedance and the resonant frequency for the sensor, it is possible to get the capacitance and resistance from which the temperature and humidity can be extracted. The results presented here show that the sensitivity of the passive wireless sensor is about −17.80 kHz/%RH and $7.32~\Omega $ /%RH at 25 °C from 55%RH to 95%RH, and it is about −7.69 kHz/°C and $6.27~\Omega $ /°C at 65%RH from 10 °C to 40 °C. [2014-0311]
TL;DR: In this article, an enhanced locking range technique for a CMOS injection-locked frequency divider (ILFD) is presented, which uses a cross-coupled oscillator with a dual-resonance RLC resonator.
Abstract: An enhanced locking range technique for a CMOS injection-locked frequency divider (ILFD) is presented, which uses a cross-coupled oscillator with a dual-resonance RLC resonator. This ILFD has dual locking ranges at a fixed bias, and the resistor in the resonator is used to have overlapping dual locking ranges so that a single-band wide-locking range is obtained. At the incident power of 0 dBm, the locking range of the divide-by-2 ILFD is 6.7 GHz, from 3 to 9.7 GHz, and the locking range percentage is 105.51%.
TL;DR: The necessary and sufficient conditions for the existence of such a realization of fractional-order impedance functions by passive electrical networks composed of a fractional capacitor and some RLC components are found in a general case.
Abstract: This paper deals with realization of fractional-order impedance functions by passive electrical networks composed of a fractional capacitor and some RLC components. The necessary and sufficient conditions for the existence of such a realization are found in a general case. Also for impedance functions described by a class of fractional-order transfer functions, the realizability conditions are stated as some algebraic conditions on the parameters of the transfer function. Moreover, a procedure is proposed for implementation of such impedance functions by passive electrical networks composed of a fractional capacitor and some RLC components. Numerical examples are presented to show the usefulness of the results of the paper in design of fractional-order electrical circuits.
TL;DR: In this paper, the potential of two-terminal graphene-hexagonal boron nitride-graphene resonant tunneling diodes as high-frequency oscillators was assessed using self-consistent quantum transport and electrostatic simulations.
Abstract: We assess the potential of two-terminal graphene-hexagonal boron nitride-graphene resonant tunneling diodes as high-frequency oscillators, using self-consistent quantum transport and electrostatic simulations to determine the time-dependent response of the diodes in a resonant circuit. We quantify how the frequency and power of the current oscillations depend on the diode and circuit parameters including the doping of the graphene electrodes, device geometry, alignment of the graphene lattices, and the circuit impedances. Our results indicate that current oscillations with frequencies of up to several hundred GHz should be achievable.
TL;DR: In this article, a beam metamaterial with a high-order resonant shunt circuit is proposed and investigated for vibration and wave propagation attenuation in a periodic piezoelectric array.
Abstract: Beam or plate metamaterials with periodic piezoelectric arrays have attracted more and more attention in recent years for wave propagation attenuation and the corresponding vibration reduction. Conventional designs use resistive shunt (R-shunt) and resistor-inductor shunt (RL-shunt). An innovative metamaterial with a high-order resonant shunt circuit is proposed and investigated for vibration and wave propagation attenuation in this paper. The proposed high-order resonant shunt circuit can introduce two local resonances in series around the tuning frequency to broaden the attenuation bandwidth, or can create two separate resonances to achieve two separate bandgaps. Finite element modeling of the beam metamaterial with wave propagation and vibration in the transverse direction is established. Simulations have been conducted to compare the vibration attenuation performances among R-shunt, RL-shunt, and the proposed high-order shunt. An impedance-based method has been presented for the parameter design of electrical components in the proposed high-order shunt for bandgaps at two desired frequencies.
TL;DR: This paper presents a low cost precise and reliable inductive absolute position measurement system that is suitable for rough industrial environments, offers a high inherent resolution, can measure target position over a wide measurement range, and can potentially measure multiple target locations simultaneously.
Abstract: This paper presents a low cost precise and reliable inductive absolute position measurement system. It is suitable for rough industrial environments, offers a high inherent resolution (0.1%–0.01% of measurement range), can measure target position over a wide measurement range, and can potentially measure multiple target locations simultaneously. The basic position resolution is improved by adding two additional finer pitched receive channels. The sensor works on principles similar to contactless resolvers. It consists of a rectangular antenna printed circuit board and a passive LC resonant circuit. A mathematical model and the equivalent circuit of this kind of sensor are explained in detail. Such sensors suffer from transmitter to receiver coil capacitive crosstalk, which results in a phase sensitive offset. This crosstalk will be analyzed by measurements. Moreover, the mechanical transducer arrangement, the measurement setup, and the measured results will be presented.
TL;DR: A novel simple DM EMI suppressor for the LLCL-filter-based system is proposed to achieve a small value of capacitor as well as to minimize the additional reactive power.
Abstract: The single-phase power converter topologies evolving of photovoltaic applications are still including passive filters, like the $LCL$ - or $LLCL$ -filter. Compared with the $LCL$ -filter, the total inductance of the $LLCL$ -filter can be reduced a lot. However, due to the resonant inductor in series with the bypass capacitor, the differential mode (DM) electromagnetic interference (EMI) noise attenuation of an $LLCL$ -filter-based grid-tied inverter declines. Conventionally, a capacitor was inserted in parallel with the $LC$ resonant circuit branch of the $LLCL$ -filter to suppress the DM EMI noise. In order to achieve a small value of capacitor as well as to minimize the additional reactive power, a novel simple DM EMI suppressor for the $LLCL$ -filter-based system is proposed. The characters of two kinds of DM EMI suppressor are analyzed and compared in detail. Simulations and experiments on a 0.5-kW 110-V/50-Hz single-phase grid-tied inverter prototype are accomplished to confirm the analysis.
TL;DR: This paper presents an induction heating high power supply composed by a single inverter circuit and a specially designed output resonant circuit that supplies simultaneously both medium- and high-frequency power signals to the heating inductor.
Abstract: The induction surface hardening of parts with nonuniform cylindrical shape requires a multifrequency process in order to obtain a uniform surface hardened depth. This paper presents an induction heating high power supply composed by a single inverter circuit and a specially designed output resonant circuit. The whole circuit supplies simultaneously both medium- and high-frequency power signals to the heating inductor. An initial study is made to select the most appropriated topology for this application. The resonant output circuit is analyzed, and a design procedure is presented. The selected inverter operation is described and simulated. Simulations are experimentally verified on a 10-kW dual-frequency resonant inverter operating at 10 and 100 kHz using MOSFETs of silicon (Si) and silicon carbide (SiC) technology. A comparative study is presented based on the measurements of power losses and the energy efficiency of the inverter using both types of MOSFETs.
TL;DR: In this paper, the load adaptability of a 12-pulse rectifier with an active interphase reactor (AIPR) and corresponding auxiliary circuit is analyzed, and the appropriate amplitude of the circulating current under RL-type load and the LC filter under RLC -type load are presented.
Abstract: In order to improve the harmonic reduction ability of 12-pulse rectifier, an active interphase reactor (AIPR) and corresponding auxiliary circuit are often used to produce circulating current resulting in harmonic reduction. This paper analyzes the load adaptability of 12-pulse rectifier with AIPR. The loads are classified into three types, RL -type load, RC -type load, and RLC -type load. Load currents and circulating currents are calculated under different load types. According to the calculation results, the THD of input line current and ripple coefficient of load voltage are also described by figures under RL -type load and RLC -type load. The appropriate amplitude of the circulating current under RL -type load and the LC filter under RLC -type load are presented. Simulation and experimental results validate the theoretical analysis.
TL;DR: In this paper, a flexible micro-perforated panel absorber based on Polyvinylidene fluoride (PVDF) piezoelectric film is proposed, which is composed of a perforated aluminum-electrode PVDF and a small air cavity.
TL;DR: A high-efficiency management circuit using a multiwinding upconversion current transformer (CT) for power-line energy harvesting and an instantaneous discharging circuit that is suitable for weak energy harvesting is developed.
Abstract: This paper presents a high-efficiency management circuit using a multiwinding upconversion current transformer (CT) for power-line energy harvesting. Due to sharing the same loop for matching and charging in a low working frequency (50 Hz), the traditional matching circuit of the CT has a low $Q$ value and low magnetoelectric efficiency, and it cannot be used in both a weak power-line current and a heavy load. A multiwinding CT upconversion matching circuit with a higher $Q$ value is developed. Higher charging power (> 175%) and a larger ultimate charging voltage (> 150%) in a weak power-line current (1–100 A) can be obtained by using an independent upconversion resonant matching loop. The matching circuit can efficiently work at a wider load capacitance. In order to drive a wireless sensor with higher power consumption, an instantaneous discharging circuit that is suitable for weak energy harvesting (< 700 μW) is developed. The instantaneous discharging circuit can accumulate weak energy from a CT transducer during a long period, and it can provide a higher power output in a very short time. The management circuit can drive a wireless sensor with an output power of 60 mW at a distance of over 40 m. The multiwinding high-efficiency upconversion management circuit can be used in many other low-frequency energy harvesters.
TL;DR: This paper suggests a single-phase and single-stage battery charger for a light electric vehicle to improve the lifetime by removing high voltage electrolytic capacitors and increases the power factor by removing dead zones in the line current and reduces the switching loss of the valley-fill circuit.
Abstract: This paper suggests a single-phase and single-stage battery charger for a light electric vehicle to improve the lifetime by removing high voltage electrolytic capacitors. The proposed charger is based on a diode-clamped series resonant converter equipped with a resonant valley-fill circuit, which increases the power factor by removing dead zones in the line current and reduces the switching loss of the valley-fill circuit. The feasibility of the proposed charger has been verified with a 1.7-kW prototype.
TL;DR: A wireless passive temperature sensor designed on the basis of a resonant circuit, fabricated on multilayer high temperature cofired ceramic (HTCC) tapes, and measured with an antenna in the wireless coupling way demonstrates good high-temperature characteristics and wide temperature range.
Abstract: A wireless passive temperature sensor is designed on the basis of a resonant circuit, fabricated on multilayer high temperature cofired ceramic (HTCC) tapes, and measured with an antenna in the wireless coupling way. Alumina ceramic used as the substrate of the sensor is fabricated by lamination and sintering techniques, and the passive resonant circuit composed of a planar spiral inductor and a parallel plate capacitor is printed and formed on the substrate by screen-printing and postfiring processes. Since the permittivity of the ceramic becomes higher as temperature rises, the resonant frequency of the sensor decreases due to the increasing capacitance of the circuit. Measurements on the input impedance versus the resonant frequency of the sensor are achieved based on the principle, and discussions are made according to the exacted relative permittivity of the ceramic and quality factor () of the sensor within the temperature range from 19°C (room temperature) to 900°C. The results show that the sensor demonstrates good high-temperature characteristics and wide temperature range. The average sensitivity of the sensor with good repeatability and reliability is up to 5.22 KHz/°C. It can be applied to detect high temperature in harsh environment.
TL;DR: In this paper, a generalized model for characterizing the inverter-cable-motor system with the filter included was formulated to describe the interactions between the filter and the drive system.
Abstract: Inverter-fed drive systems have been widely used in residential, commercial, and industrial applications. Special emphasis is placed on avoiding overvoltage spikes traveling along the cable and inside the motor, when a long motor cable is used. Such phenomenon would cause premature failure of the motor and cable insulation. Many passive and active overvoltage suppression techniques have been proposed to tackle this issue. Among them, passive overvoltage filters are dominant solutions, as their implementation is simple, cost effective, and robust. However, they have the main drawback of high power dissipation. This paper gives a new perspective on this subject. A generalized model for characterizing the inverter-cable-motor system with the filter included will be formulated to describe the interactions between the filter and the drive system. Then, the characteristics of an ideal overvoltage filter will be derived. Furthermore, a low-loss filter, named as “RL-plus-C” filter that exhibits near ideal characteristics will be proposed. Its performance will be compared with that of the commonly adopted RC and RLC filters, theoretically and experimentally on a 1-hp motor drive system. Results reveal that the proposed filter has the lowest power dissipation.
TL;DR: In this paper, the functional relation between the fractional bandwidth and the quality factor of a radiating system is investigated, and it is shown that for a first-order system, only the quality factors based on differentiation of the input impedance has unique proportionality to the FBR, whereas, e.g., the classical definition of the QF, i.e., the ratio of the stored energy to the lost energy per one cycle, is not uniquely proportional to the fBR.
Abstract: The functional relation between the fractional bandwidth and the quality factor of a radiating system is investigated in this communication. Several widely used definitions of the quality factor are compared with two examples of RLC circuits that serve as a simplified model of a single-resonant antenna tuned to its resonance. It is demonstrated that for a first-order system, only the quality factor based on differentiation of the input impedance has unique proportionality to the fractional bandwidth, whereas, e.g., the classical definition of the quality factor, i.e., the ratio of the stored energy to the lost energy per one cycle, is not uniquely proportional to the fractional bandwidth. In addition, it is shown that for higher order systems, the quality factor based on differentiation of the input impedance ceases to be uniquely related to the fractional bandwidth.
TL;DR: In this article, a triple band notched coplanar waveguide fed planar monopole antenna is presented for ultrawideband applications, which is achieved using a novel mushroom type electromagnetic band gap structure like resonator and a split ring slot.
Abstract: To mitigate the interference with coexisting wireless systems operating over 3.3-3.6 GHz, 5.15-5.825 GHz, and 7.725-8.5 GHz bands, a novel triple band notched coplanar waveguide fed pitcher-shaped planar monopole antenna is presented for ultrawideband applications. Bands notched characteristics are achieved using a novel mushroom type electromagnetic band gap structure like resonator and a split ring slot. A conceptual equivalent RLC Resistor-Inductor-Capacitor-resonant circuit is presented for the band notched characteristics. Furthermore, the input impedance and VSWR voltage standing wave ratio obtained from the equivalent circuit are validated with simulated and measured results. Performances of the antennas in both, the frequency domain and the time domain are investigated. The simulated and measured results demonstrate that the proposed antennas have wide impedance bandwidth, nearly stable radiation patterns, and suppression of gain and total radiation efficiency at notched bands. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:795-806, 2015.
26 Jul 2015
TL;DR: In this article, a small-signal impedance method is proposed for series-compensated power systems including DIFs, based on which, a practical series compensated power system including DFIGs can be simplified into a second-order series RLC circuit around the operating point concerned and then the frequency and stability of SSR can be intuitively represented by the equivalent parameters of the circuit.
Abstract: Interaction between fixed series compensation and doubly-fed induction generator (DFIG)-based wind farms can cause a new type of subsynchronous resonance (SSR) problem, which is also named as subsynchronous control interaction (SSCI). To explain its basic mechanism as well as to evaluate the risk, this paper proposes a small-signal impedance method, based on which, a practical series-compensated power system including DFIGs can be simplified into a second-order series RLC circuit around the operating point concerned and then the frequency and stability of SSR can be intuitively represented by the equivalent parameters of the circuit. The derivation of the circuit parameters is given and the asymmetry phenomenon of equivalent impedance matrix in dq0 reference frame is observed. Both Eigenvalue analysis and time-domain simulation have verified the effectiveness of the proposed method and its advantage in accuracy over the existing impedance-based method. The impacts on SSR due to wind speed, number of online DFIGs and their control parameters are also investigated.
10 Sep 2015
TL;DR: In this article, the authors present some physical interpretations of recent stability results on the feedback interconnection of negative imaginary systems, which involve spring mass damper systems coupled together by springs or RLC electrical networks coupled together via inductors or capacitors.
Abstract: This paper presents some physical interpretations of recent stability results on the feedback interconnection of negative imaginary systems. These interpretations involve spring mass damper systems coupled together by springs or RLC electrical networks coupled together via inductors or capacitors.
TL;DR: Comparison of experimental results for several benchmark circuits shows that proposed evolutionary algorithm enables optimal or near-optimal solutions with lesser Gate Counts.