Showing papers on "Electronic filter published in 2013"

Investigation and Active Damping of Multiple Resonances in a Parallel-Inverter-Based Microgrid

Abstract: This paper addresses the resonance problem in a parallel-inverter-based grid-interactive microgrid. Unlike the single grid-connected inverter system where the resonance frequency is mainly fixed by the inverter output LCL filter parameters, the parallel-inverter-based grid-interactive microgrid system presents a more challenging picture where inverter interactions will excite complex resonances at various frequencies. As a result, line currents of inverters can be severely distorted even when the control schemes and filter circuits are properly designed based on the single-inverter model. This paper first develops a microgrid model using discrete time-domain closed-loop Norton's equivalent circuit. Multiple resonances can then be evaluated with the developed model. To improve the microgrid power quality, this paper also designs a virtual-harmonic-resistance-based active damping method. The proposed damping method can be seamlessly incorporated into the conventional deadbeat control scheme through the direct control reference modification. Therefore, the active damping method is able to address both the transient and steady-state resonances within the deadbeat current control bandwidth. Simulation and experimental results are provided to validate the correctness of the developed resonance modeling and active damping methods.

Control of Improved Full-Bridge Three-Level DC/DC Converter for Wind Turbines in a DC Grid

Abstract: This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis.

Direct current (DC)-DC converter having a multi-stage output filter

Abstract: A direct current (DC)-DC converter that includes a first switching converter and a multi-stage filter is disclosed. The multi-stage filter includes at least a first inductance (L) capacitance (C) filter and a second LC filter coupled in series between the first switching converter and a DC-DC converter output. The first LC filter has a first LC time constant and the second LC filter has a second LC time constant, which is less than the first LC time constant. The first switching converter and the multi-stage filter form a feedback loop, which is used to regulate the first switching power supply output signal based on the setpoint. The first LC filter includes a first capacitive element having a first self-resonant frequency, which is about equal to a first notch frequency of the multi-stage filter.

Coupled-Inductor Filter: A Basic Filter Building Block

Abstract: Coupled-magnetics and coupled-inductor filters provide smoothing in a power converter by steering ripple current away from the “quite port.” While this concept is not new, topologies claiming to be “new” or “novel” continue to be reported in the literature, suggesting that the ripple-steering phenomenon may not be well understood to be a property of the filter block itself. This paper describes a general coupled-inductor filter block and presents a brief history of its application starting with the earliest known version of the circuit, which dates back to a 1923 patent application. The coupled-inductor circuit model is reviewed, starting with the basic topology and ideal circuit elements. Real circuit elements are then considered along with the effects of equivalent series resistance and other parasitic elements. A circuit-based filtering approach is used to emphasize the filtering aspect of the coupled inductor. It will be seen that the coupled-inductor filter can exhibit a low pass with notch frequency response. This provides the ability to achieve extra attenuation at a particular frequency, such as the converter switching frequency, which can reduce the overall filtering burden without adding extra inductive components. When the filter components are treated as a functional circuit group, instead of an interconnection of inductors and capacitors, the coupled-inductor filter can be analyzed as a drop-in replacement wherever a smoothing choke would normally be used and does not depend on converter voltage waveforms. A topology transformation of the Cuk converter shows that “zero ripple” in not a special property of the topology, but can be achieved using the coupled-inductor filter block.

Passive $LC$ Filter Design Considerations for Motor Applications

Abstract: This paper provides design guidelines for the passive LC filters Based on these guidelines, a method to design a new type of a passive filter, called hybrid LC filter, is proposed A filter design example accompanies the considerations; simulation and test results of the proposed filter in time and frequency domains are shown

Review of hybrid active power filter topologies and controllers

Abstract: Hybrid active power filter (HAPF) consisting of passive filter and active filter in various configurations to each other has now become preferred technology for harmonic compensation in two wire, three wire and four wire ac power networks with nonlinear loads. This paper presents a detailed survey of hybrid active power filters considering converter topologies, supply system and passive filter type. In addition, the control strategies are discussed in detail. The main aim of this paper is to provide a broad perspective on the status of HAPF technology to researchers and application engineers dealing with power quality. More than eighty research papers are reviewed and classified into categories and subcategories.

A Three-Level Converter With Reduced Filter Size Using Two Transformers and Flying Capacitors

Abstract: This paper proposes a pulse-width modulation three-level converter with reduced filter size using two transformers. The proposed converter has many advantages. All switches sustain only the half of the input voltage and since the secondary rectified voltage is a three-level waveform, the output filter inductor can be reduced. Also, because of the power sharing of transformer and reduced output inductor, high efficiency can be obtained. The operational principle, analysis, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from a prototype with 600 W, 500-600 V input, and 60 V output.

Analysis and improvement of performance in LCL filter-based PWM rectifier/inverter application using hybrid damping approach

Abstract: A hybrid passive-active damping solution with improved system stability margin and enhanced dynamic performance is proposed for high power grid interactive converters. In grid connected active rectifier/inverter application, line side LCL filter improves the high frequency attenuation and makes the converter compatible with the stringent grid power quality regulations. Passive damping though offers a simple and reliable solution but it reduces overall converter efficiency. Active damping solutions do not increase the system losses but can guarantee the stable operation up to a certain speed of dynamic response which is limited by the maximum bandwidth of the current controller. This paper examines this limit and introduces a concept of hybrid passive-active damping solution with improved stability margin and high dynamic performance for line side LCL filter based active rectifier/inverter applications. A detailed design, analysis of the hybrid approach and trade-off between system losses and dynamic performance in grid connected applications are reported. Simulation and experimental results from a 10 kVA prototype demonstrate the effectiveness of the proposed solution. An analytical study on system stability and dynamic response with the variations of various controller and passive filter parameters is presented.

Design and Analysis of Integrator-Based Log-Domain Filter Circuits

Abstract: Foreword R. Adams. Preface. 1. Introduction. 2. Log-Domain Integrators. 3. Log-Domain Filter Synthesis-I: Operational Simulation of LC Ladders. 4. Log-Domain Filter Synthesis-II: State-Space Formulation. 5. Nonideality Analysis of Biquadratic Log-Domain Filters. 6. Extending the Nonideality Analysis to High-Order Ladder Filters. 7. Experimental IC Prototypes. Appendices. References. Index.

Sinusoidal PWM Signal Generation Technique for Three Phase Voltage Source Inverter with Analog Circuit & Simulation of PWM Inverter for Standalone Load & Micro-grid System

Abstract: Inverter is the most important device to utilize the renewable energy sources efficiently. The Sinusoidal Pulse Width Modulation (SPWM) technique is one of the most popular PWM techniques for harmonic reduction of inverters since there are used three sine waves displaced in 120 0 phase difference as reference signals for three phase inverter. Nowadays the SPWM switching signal is generated with the help of different FPGAs, microcontrollers and microprocessors. But for these kind of devices it is necessary the programming or coding. This paper represents the SPWM technique for harmonic reduction & shows how to generate SPWM switching signal using different simple Operational-Amplifier (Op-Amp) circuits/analog circuits for three phase pulse width modulated (PWM) voltage source inverter (VSI). All the Op-Amp circuits are simulated and their outputs are shown step by step. This analog circuit (Op-Amp) controlled voltage source inverter is simulated for both standalone load & high voltage sensitive loads/systems like micro-grid system and large industrial machines respectively with transformer & without transformer. The simulation results are shown before and after harmonic reduction using an appropriate passive filter. Furthermore, the paper represents two typical inverter based micro grid system structures where one is with common DC bus & another one is with common AC bus.

Frequency Based Feedback Control

Abstract: Disclosed herein is a feedback reduction system for used in a hearing prosthesis. The hearing prosthesis will receive an input signal, process the input signal, and create a transformed output. However, the hearing prosthesis may suffer from feedback. Thus, a system to minimize the feedback in a hearing prosthesis may be desirable. One system to minimize the feedback includes down-sample circuitry configured to down-sample a first signal, creating a down-sampled signal. They system also includes a filter circuit. The filter circuit filters both the first signal and the down-sampled signal. The filter will output a filtered signal and a filtered down-sampled signal, respectively. Additionally, the system features up-sample circuitry that up-samples the filtered down-sampled signal. The output of the up-sample circuitry is an up-sampled signal. Further, the system features combining circuitry that creates a feedback-reduced signal based on the up-sampled signal, the filtered signal, and an input signal.

Realization of first-order current-mode filters with low number of mos transistors

Abstract: In this paper, a new current-mode (CM) circuit for realizing all of the first-order filter responses is suggested. The proposed configuration contains low number of components, only two NMOS transistors both operating in saturation region, two capacitors and two resistors. Major advantages of the presented circuit are low voltage, low noise and high linearity. The proposed filter circuit can simultaneously provide both inverting and non-inverting first-order low-pass, high-pass and all-pass filter responses. Computer simulation results achieved through SPICE tool and experimental results are given as examples to demonstrate performance and effectiveness of the proposed topology.

Low-cost and wideband frequency tunable optoelectronic oscillator based on a directly modulated distributed feedback semiconductor laser.

Abstract: A novel scheme to realize a low-cost and wideband frequency tunable optoelectronic oscillator based on a directly modulated distributed feedback (DFB) semiconductor laser is proposed and experimentally demonstrated. In the proposed scheme, neither an external modulator nor an electrical filter is used, and no more than 25 dB of the electrical loop gain is required due to the high modulation efficiency of the relaxation oscillation frequency of the DFB laser. Microwave signals with frequency coarsely tuned from 3.77 to 8.75 GHz are generated by changing the bias current and operation temperature of the DFB laser. The single sideband phase noise of the generated 6.97 GHz microwave signal is measured to be −103.6 dBc/Hz at 10 kHz offset.

Design of the LCL+trap filter for the two-level VSC installed in a large-scale wave power plant

Abstract: This paper presents a methodology for designing the link passive filter of the power converters installed in a multi-megawatt wave power plant. Such filter is based on the superposition of both LCL and trap filter configurations with the purpose of achieving enhanced grid interaction of a two-level voltage source converter. The LCL+Trap filter design is highly dependent on the electrical network characteristics; hence the distribution system of the plant is introduced in the paper to take into account its effects on the tuning parameters. The proposed LCL+trap filter topology arises as a successful alternative solution for the conventional LCL filter topology, thanks to its improved filtering capability while ensuring a reduced filter size. The validation of the proposed filter performance is evaluated in simulation by performing a comparative analysis between the LCL+trap and the LCL filters when operate in a wave farm application.

A Highly Linear Fully Integrated Powerline Filter for Biopotential Acquisition Systems

Abstract: Powerline interference is one of the most dominant problems in detection and processing of biopotential signals. This work presents a new fully integrated notch filter exhibiting high linearity and low power consumption. High filter linearity is preserved utilizing active-RC approach while IC implementation is achieved through replacing passive resistors by R-2R ladders achieving area saving of approximately 120 times. The filter design is optimized for low power operation using an efficient circuit topology and an ultra-low power operational amplifier. Fully differential implementation of the proposed filter shows notch depth of 43 dB (78 dB for 4th-order) with THD of better than -70 dB while consuming about 150 nW from 1.5 V supply.

Electronically tunable current-mode biquad filter employing CCCDTAs and grounded capacitors with low input and high output impedance

Abstract: In this study, a single-input multiple-outputs current-mode analog biquadratic filter, based on current controlled current differencing transconductance amplifier (CCCDTA) is presented. The proposed filter uses two CCCDTAs and two grounded capacitors without any external resistors, which is well suited for integrated circuit implementation. The filter simultaneously gives 3 standard transfer functions, namely, lowpass, highpass and bandpass filters with independent control of quality factor and pole frequency by electronic method. By summing of IHP and LLP, the notch filter can be also achieved. Moreover, the circuit has low input and high output impedance which would be an ideal choice for cascading in current-mode circuit. The PSPICE simulation results are included verifying the workability of the proposed filter. The given results agree well with the theoretical anticipation.

Harmonics & Its Mitigation Technique by Passive Shunt Filter

Abstract: This paper presents the study of harmonics present in the system & harmonics filter of primarily used in electrical system & worldwide. Through this paper we come to know about the harmonics & their significance effect on the system regarding the harmonics distortion caused by non- linear load such as computers, Variable frequency drives, & rectifier circuit. In this presentation we presented some of simple but not the least harmonics filter which is given as PASSIVE SHUNT FILTERS are also introduced with their respective designing methods. The basic object of this paper is to study about the designing of passive shunt type filter for the distribution system. These filters are very much affective in reduction of harmonics & distortion in voltage caused by non linear load. Here we studied design process of single tuned & high pass filter. The major objective in this study will tell us the use of shunt passive filter, their designing criteria.

Symmetry-Breaking Bifurcation in Series-Parallel Load Resonant DC-DC Converters

Abstract: This paper reports the occurrence of symmetry-breaking bifurcation in the series-parallel load-resonant dc-dc converter with L-C output filter. The constant frequency phase shift modulation technique is employed with proportional-integral controller in the output voltage regulation. The complexity of the system is contributed by the fact that a six dimensional state space is divided into twelve subsystems by six switching surfaces. It is shown that the dynamics are not only related to the resonant components but are also heavily dependent on the output filter design. The understanding of the dynamics resulting from the interaction between the resonant tank and the filter circuit helps in designing more reliable converters. We show that the first instability can be caused by Neimark-Sacker as well as symmetry-breaking bifurcations. Stable as well as unstable periodic orbits are identified, and their characteristic multipliers are computed by a newly developed algorithm based on a combination of Filippov's theory and shooting method with Newton-Raphson algorithm.

Development of UWB HTS Bandpass Filters With Microstrip Stubs-Loaded Three-Mode Resonator

Abstract: We developed ultra-wideband high-temperature superconducting bandpass filters for Japan's low-band spectrum. First, we designed a low-band filter with a microstrip three-mode resonator loaded with two open stubs. The three-mode resonator is characterized by the ease of controlling the frequency response compared with other resonators. In addition, we loaded a low-pass filter consisting of a microstrip coupled-line hairpin unit to suppress all unwanted high-frequency harmonics. The simulated filtering characteristics of the low-band filter showed a wide passband within 3.44-4.67 GHz with a minimum insertion loss of 0.06 dB. After that, we fabricated a low-band filter with YBCO thin films deposited on sapphire substrates. The frequency response of the fabricated filter was clearly observed at 70 K, and the measured response without any tuning matched well with the simulated one. The measured filtering characteristics showed a wide passband within 3.46-4.80 GHz with a minimum insertion loss of 0.01 dB. The box resonances of the copper housing were suppressed by introducing radar absorbent material under the top metal.

Low-voltage power line carrier communication circuit

Abstract: The utility model relates to a low-voltage power line carrier communication circuit. The circuit comprises a carrier control circuit, a zero-cross detection circuit and a signal coupling circuit. A signal amplifying filter circuit and a receiving filter circuit are arranged between the carrier control circuit and the signal coupling circuit. The signal amplifying filter circuit amplifies and filters analog signals output by the carrier control circuit, and then the analog signals enters into a power line information channel to be transmitted through the signal coupling circuit. The signals transmitted in the power line information channel are converted by the signal coupling circuit, then high-frequency interference is eliminated by the receiving filter circuit, and the signals are transmitted to the carrier control circuit. The signal amplifying filter circuit is connected with a current-limiting circuit to control the output current of the carrier control circuit. The zero-cross detection circuit is connected between the carrier control circuit and a power line to carry out zero-cross detection on power network power frequency signals. The low-voltage power line carrier communication circuit is simple in circuit, and is low in power dissipation, high in fidelity and high in carrier communication property due to the fact that the signal amplifying filter circuit and the current-limiting circuit are added.

Current Differencing Cascaded Transconductance Amplifier (CDCTA) and Its Applications on Current-Mode nth-Order Filters

Abstract: In this paper, a new active device, current differencing cascaded transconductance amplifier (CDCTA), has been presented. The proposed CDCTA simplifies the design of the current-mode filter circuit considerably, especially the design of high-order filter. Moreover, a current-mode nth-order filter based on the CDCTA is proposed in the paper. The proposed circuit, which adopts only an active component and n grounded capacitors, contains minimal active component and passive one. It enjoys the simple configuration and is suitable for integrated circuit (IC) fabrication. PSpice simulations for current-mode third-order filter based on this structure have also been conducted, and the results are in good agreement with the theoretical analysis. The influences of the CDCTA non-idealities are also discussed.

A Multi-Band Low-Noise Transmitter With Digital Carrier Leakage Suppression and Linearity Enhancement

Abstract: A low-noise multi-band transmitter for GSM quad-band and WCDMA is presented. Programmable parameters of the analog baseband and the RF frontend enable adaption for different protocols and frequency bands. A three-step carrier leakage calibration algorithm is proposed to suppress the leakage to -65 dBm at highest RF gain. Novel linearization methods are used in the low-pass filter and the driver power amplifier to meet the demand of 3G systems. The noise floor achieves -157 dBc/Hz at 190 MHz frequency offset in WCDMA band, which eliminates the need for external SAW filter.

A high performance C-band FBAR filter

Abstract: In this paper a RF band pass filter in C-band based on film bulk acoustic resonator (FBAR) technology is developed. The measured insertion loss is less than 2.0 dB at the center frequency (5.2GHz) of the filter, and the signal attenuation near the pass band of the filter is greater than 50 dB. The measurement data are in good agreement with the design employing three dimensional electromagnetic simulation techniques. A method to move the transmission zeros of the FBAR filter is proposed by adding a capacitor element between the two shunt branches of the filter. Using the technique, an FBAR filter chip can be configured to meet different rejection specifications potentially.

Systems and methods for reducing filter insertion loss while maintaining out-of-band attenuation

Abstract: Disclosed are systems and methods for reducing filter insertion loss while maintaining out-of-band attenuation. In some embodiments, a system can be configured for processing of radio-frequency (RF) signals. The system can include a plurality of signal paths configured to accommodate multiple frequency bands, with each of the multiple bands having a passband. The system can further include a filter circuit disposed along each of the signal paths. At least one of the filter circuits can be segmented into two or more segments that substantially cover the passband corresponding to the filter circuit. The segmented filter circuit can be configured to provide a desired attenuation of out-of-band interferers and a desired insertion loss level. In some embodiments, the signal paths can include receive (Rx) paths.

High-Performance, Compact Quasi-Elliptic Band Pass Filters for V-Band High Data Rate Radios

Abstract: This paper presents a comparison of the design and implementation of V-band quasi-elliptic band pass filters suitable for system-on-package integration at millimetre-wave frequencies. Filters were designed and manufactured at low-temperature co-fired ceramic (LTCC) and alumina substrates. Filter circuits include the input/output coplanar waveguide to microstrip transitions as well as the microwave pads, used to facilitate measurement. Three four-pole filters incorporating half-wavelength resonators were implemented, two planar (on LTCC and alumina substrates) and one vertically stacked (on LTCC). In addition a six-pole filter was also implemented in alumina. The four-pole LTCC based filters have a measured insertion loss (IL) as low as 3.4 dB, fractional bandwidth (FBW(%) = BW-3 dB/Center Frequency) of 4.8% and return loss better than 10 dB. Total filter size is less than 1.1 × 0.74 mm. The alumina-based four-pole/six-pole filters exhibit a measured IL of 2.8/3.1 dB, FBW of 8.3%/12.6%, respectively. Both alumina filters exhibit a return loss better than 10 dB and with a corresponding filter layout footprint of less than 1.01 × 1.34 mm. A new figure-of-merit (HPFOM) is proposed and results from the filters proposed here clearly show they offer the best trade-off between performance and area (higher HPFOM).

Frequency Limitations of First-Order $g_{m} - RC$ All-Pass Delay Circuits

Abstract: All-pass filter circuits can implement a time delay but, in practice, show delay and gain variations versus frequency, limiting their useful frequency range. This brief derives analytical equations to estimate this frequency range, given a certain maximum allowable budget for variation in delay and gain. We analyze and compare two well-known gm - RC first-order all-pass circuits, which can be compactly realized in CMOS technology and relate their delay variation to the main pole frequency. Modeling parasitic poles and putting a constraint on gain variation, equations for the maximum achievable pole frequency and delay variation versus frequency are derived. These equations are compared with simulation and used to design and compare delay cells satisfying given design goals.