Showing papers on "Electronic filter published in 2016"

A Review of Passive Power Filters for Three-Phase Grid-Connected Voltage-Source Converters

Abstract: In order to reduce size and cost, high-order passive filters are generally preferred in power converters to cancel out high-frequency harmonics caused by pulsewidth modulation. However, the filter resonance peaks may require the use of passive dampers to stabilize the interactions between the load and source impedances. Furthermore, the stabilizing effect is more difficult to be guaranteed for cost-optimized filters, which are characterized by low-inductance and high-capacitance passive components. In this paper, several passive filter topologies used to interface voltage-source converters with the utility grid are reviewed and evaluated in terms of damping capability, stored energy in the passive components, and power loss in the damping circuit. In addition, the influences of different switching frequencies of power converters on the passive filter design are discussed in the range 1–15 kHz. Illustrative design examples of the passive filters and experimental data are also provided.

Design of LCL Filters With LCL Resonance Frequencies Beyond the Nyquist Frequency for Grid-Connected Converters

Abstract: This paper proposes a novel LCL filter design method and its current control for grid-connected converters. With the proposed design method, it is possible to set the resonance frequency of the LCL filter to be higher than the Nyquist frequency, i.e., half of the system sampling frequency, and this observation is so far not discussed in the literature. In this case, a very cost-effective LCL filter design can be achieved for the grid-connected converters, whose dominant switching harmonics may appear at double the switching frequency, e.g., in unipolar-modulated three-level full-bridge converters and 12-switch-based three-phase pulsewidth-modulated converters. Moreover, a single-loop current control strategy is proposed for the designed LCL filter, and the control system is inherently stable without introducing any passive or active damping. Based on the new stability region, two LCL filter design examples are given, with one of them optimizing the utilization of passive filter inductors, and another one being robust against grid impedance variation. Comprehensive experimental results, showing the high-quality output current and excellent resonance attenuation, are presented in this paper, which are also in very good agreement with those of the simulated ones. These results successfully verify the feasibility of the proposed LCL filter design and its current control.

$W$ -Band Waveguide Filters Fabricated by Laser Micromachining and 3-D Printing

Abstract: This paper presents two W-band waveguide bandpass filters, one fabricated using laser micromachining and the other 3-D printing. Both filters are based on coupled resonators and are designed to have a Chebyshev response. The first filter is for laser micromachining and it is designed to have a compact structure allowing the whole filter to be made from a single metal workpiece. This eliminates the need to split the filter into several layers and therefore yields an enhanced performance in terms of low insertion loss and good durability. The second filter is produced from polymer resin using a stereolithography 3-D printing technique and the whole filter is plated with copper. To facilitate the plating process, the waveguide filter consists of slots on both the broadside and narrow side walls. Such slots also reduce the weight of the filter while still retaining the filter’s performance in terms of insertion loss. Both filters are fabricated and tested and have good agreement between measurements and simulations.

Tailoring of the Brillouin gain for on-chip widely tunable and reconfigurable broadband microwave photonic filters

Abstract: An unprecedented Brillouin gain of 44 dB in a photonic chip enables the realization of broadly tunable and reconfigurable integrated microwave photonic filters. More than a decade bandwidth reconfigurability from 30 up to 440 MHz, with a passband ripple <1.9 dB is achieved by tailoring the Brillouin pump. The filter central frequency is continuously tuned up to 30 GHz with no degradation of the passband response, which is a major improvement over electronic filters. Furthermore, we demonstrate pump tailoring to realize multiple bandpass filters with different bandwidths and central frequencies, paving the way for multiple on-chip microwave filters and channelizers.

Active / passive harmonic filters: Applications, challenges & trends

Abstract: The goal of this paper is to present the different applications, challenges and trends for traditional active and passive harmonic filters for reduction of harmonic distortion and optimization of the power quality. Emphasis is put on real cases applied in the industry for passive tuned filters and for active harmonic filters analyzing the advantages and disadvantages of active versus passive filter technologies.

Modeling and Stability Analysis of Active/Hybrid Common-Mode EMI Filters for DC/DC Power Converters

Abstract: Hybrid electromagnetic interference (EMI) filters (HEFs), which are composed of an active filter and a passive filter, have been proposed to reduce the size and weight of conventional passive EMI filters in literatures. However, accurate models that can be used to predict the stability and performance of HEFs have not been developed. To cope with this, this paper presents a modeling technique for a hybrid common-mode (CM) filter. The technique can be applied to the modeling of other HEFs. Critical component models were first developed for the HEF. HEF's overall model was further developed based on these individual component models. Experimental results validated that the developed model can successfully predict the stability and performance of active/hybrid CM filters.

A Passive Filter Building Block for Input or Output Current Ripple Cancellation in a Power Converter

Abstract: This paper analyzes a coupled inductor based $LL$ – $LC$ network as a building block to achieve input or output current ripple cancellation in power converters. The proposed current ripple cancellation technique works on the principle of inductance matching. It also provides reduced current stress on the switching devices of the converter compared with the other current ripple cancellation networks discussed in the literature. The current ripple cancellation technique is verified in achieving input and output current ripple minimization in different converters. The effect of inductance mismatch, inductor and capacitor tolerances, and circuit parasitic is also studied. Some of the published research works are demonstrated to be a special case of the proposed idea. The effectiveness of the proposed method is validated by demonstrating the zero-ripple input current using a 31 V dc to 60 V dc, 240 W boost converter prototype and a 31 V dc to 115 V (rms) ac, 320 W current-fed-switched inverter prototype, and the zero-ripple output current using a 62 V to 42 V dc, 450 W buck converter prototype.

Stability Analysis and Robust Design of LCL With Multituned Traps Filter for Grid-Connected Converters

Abstract: Utilizing high-order passive filters for the voltage-source converters is becoming attractive in industrial applications due to the excellent attenuation performance, smaller size, and lower cost. The LCL , the multituned traps, and recently the combined LCL with multituned traps ( LCL-mT ) are the most popular high-order filters. However, the increased number of elements and the inherent resonances complicate both filter parameter design and current control loop stabilization, especially, in the presence of parameter uncertainties and wide variations of the grid inductance. Hence, in this paper a straightforward and robust design procedure for the LCL-mT filter is proposed. Compared to the existing methods, the proposed technique is not iterative and satisfies the traditional practical limits on filter parameters, while ensures stability even in the presence of wide grid inductance variations and filter parameter uncertainties. The validity and effectiveness of the proposed method are proved by simulation and experimental results.

Three-Port DC/DC Converter With All Ports Current Ripple Cancellation Using Integrated Magnetic Technique

Abstract: This paper presents a novel integrated magnetic three-port converter (IMTPC) with high power density and all three ports’ current ripple cancellation. The proposed IMTPC can interface one PV port, one bidirectional battery port, and one load port of the PV-battery dc power system. Only two high power magnetic devices are needed in an IMTPC for realizing power conversion, ripple cancellation, and switch driver simultaneously. Three extra capacitors were added to achieve three ports’ current ripple cancellation. Therefore, the port of the IMTPC will always in continuous-conduction mode with “zero current ripple,” thus, size of passive filter can be reduced and accuracy of maximum power point tracking can be improved. Meanwhile, simple driving of the high-side switch can be realized by integrated magnetic winding, which is responsible for MOSFET driver's voltage level shift. The using of the integrated magnetic technique not only performs aforementioned advantages but also shows great potential for reducing the weight and volume of the dc–dc converter. Finally, experimental verifications are given to illustrate the feasibility and effectiveness of the proposed topology and control method.

Passive Filter Aided by Shunt Compensators Based on the Conservative Power Theory

Abstract: Passive filters are widely used in electrical system for power quality improvements. Their first installations from 1940 s and their advantages make them an attractive and standard solution up to nowadays. However, passive filters have their filtering characteristics deteriorated due to parameter variation caused by aging or temperature. In addition, a capacitor bank for power factor correction is designed for specific loads and may not supply the right amount of reactive power when loads keep being added or changed. When these issues make the passive filter and the capacitor bank incapable to keep the system operating within acceptable level of power quality, an inconvenience arises and a solution must be provided. A common one is to replace both of them either by new elements or by active power compensators. However, replacing the passive filter and the capacitor bank may not be economically feasible, because they belong to a past investment. This paper presents a solution to overcome such inconvenience keeping the passive filter and the capacitor bank installed and unchanged. It consists of installing two shunt compensators specially designed for performing what the passive filter and the capacitor bank are incapable to do. The result is a reduced processed power in the compensators. The generation of the references is based on conservative power theory (CPT). A case study is presented to prove the compensators’ efficacy and the power quality improvement.

Multimega VAR Passive Filters for Mining Applications: Practical Limitations and Technical Considerations

Abstract: This paper analyzes and proposes technical considerations for the selection and design of passive filter schemes rated at several mega VARs to compensate reactive power and current harmonics in mining power distribution systems. The paper includes technical information and analysis required to select the most adequate passive filter topology, to select the tuning frequency for each unit, to calculate filter parameters, and to distribute reactive power between passive filters. Passive filter schemes analyzed in this paper are used to compensate mining power distribution systems, especially when high-power grinding mill drives energized from 12-pulse cycloconverters are used in conjunction with several other nonlinear loads. This paper also analyzes technical limitations that passive filters present in the attenuation of low-frequency current harmonics. Finally, two power distribution systems with different passive filters schemes are evaluated, and the limitations in the attenuation of low-frequency current harmonics generated by cycloconverters are demonstrated with measured results.

Analysis and control of a reduced switch hybrid active power filter

Abstract: A hybrid B4 active power filter (APF) with reduced switches is proposed in this study, which is composed of a inductance–capacitance (LC) passive filter and a four-switch three-phase inverter (B4 inverter) in series connection. The LC filter is used to supply reactive power, and the active filter is responsible for mitigating the harmonics. Compared with the previous proposed four-switch hybrid APF, it can overcome the drawback of large dc voltage components appearing in the ac capacitors. Basic principles and steady-state analysis of hybrid B4 APF are introduced in detail. A control scheme based on source current detection is presented. Multiple parallel vector resonance controllers are adopted in the current control loop, and the gains of these resonance controllers are optimised by a particle swarm optimisation approach. Experimental results have verified the effectiveness of the proposed hybrid B4 APF.

Power amplification module

Abstract: A power amplification module includes a first input terminal arranged to receive a first transmission signal in a first frequency band, a second input terminal arranged to receive a second transmission signal in a second frequency band higher than the first frequency band, a first amplification circuit that amplifies the first transmission signal, a second amplification circuit that amplifies the second transmission signal, a first filter circuit located between the first input terminal and the first amplification circuit, and a second filter circuit located between the second input terminal and the second amplification circuit The first filter circuit is a low-pass filter that allows the first frequency band to pass therethrough and that attenuates a harmonic of the first transmission signal and the second transmission signal The second filter circuit is a high-pass filter that allows the second frequency band to pass therethrough and that attenuates the first transmission signal

BAW filter design method based on intrinsically switchable ferroelectric BST FBARs

Abstract: A design method for BAW filters based on intrinsically switchable ferroelectric BST FBARs is presented. A complete set of design equations for ladder-type FBAR filters is derived based on the popular filter synthesis method using image parameters. For the first time, a complete analysis is performed that accurately calculates both the image impedance and propagation constant for BAW filters. Closed-form design equations as a function of FBAR and filter specifications are provided. As an experimental verification, a 1.5-stage switchable ferroelectric BST FBAR filter is designed, fabricated, and measured. When a dc bias is applied, a switchable filter is in its on-state and provides an insertion loss of 5.77 dB with a fractional bandwidth of 1.22% at 1.97 GHz. When in its off-state, the filter exhibits more than 22 dB isolation. Circuit-level simulation results are in very good agreement with the measurement results, validating the proposed BAW filter design method.

A GaN-based 100 W two-stage wireless power transmitter with inherent current source output

Abstract: A two-stage power conversion architecture for the transmitter in wireless power transfer applications is introduced. The system achieves high efficiency at output powers up to 100W, and exhibits constant output current over varying load impedance. A front-end bridgeless totem pole rectifier provides power factor correction (PFC), necessary at the designed power level. This rectifier achieves high efficiency by eliminating the conventional diode full bridge and by achieving soft switching operation. A full bridge inverter, switching at 6.78MHz, generates the AC output. Combined with an output passive filter network, the inverter achieves constant output current with load variation without the need for dynamic feedback control. A prototype system is constructed and tested experimentally to verify operation.

Electronically tunable inverse active filters employing OTAs and grounded capacitors

Abstract: This paper introduces inverse active filters employing operational transconductance amplifiers (OTAs) and grounded capacitors. The filter circuits can realise inverse low-pass, inverse band-pass and inverse high-pass transfer functions by addition of the circuit currents. Additionally, the circuit parameters ω0, Q and H can be set orthogonally or independently by adjusting the bias currents of the OTAs. The inverse filter circuits enjoy very low sensitivities to active and passive components. The achievement examples are given together with simulation results by PSPICE.

Single-phase series active power filter with transformer-coupled matrix converter

Abstract: This study presents a series active power filter based on a single-phase matrix converter. Back-to-back voltage-source converters with nested control loops and passive filters are normally used for this application. A matrix converter, as proposed in this study, allows a simpler implementation both in terms of hardware (no grid filter and no DC link) and of control. Moreover, a novel zero-voltage compensation technique is introduced in order to reduce the distortion around the input voltage zero crossing. Simulations and experiments are used to validate the considered control methods, confirming the feasibility of the proposed architecture.

A Hybrid Filter for the Suppression of Common-Mode Voltage and Differential Mode Harmonics in Three-Phase Inverters with CPPM

Abstract: —In the motor systems driven by sinusoidal pulse width modulation (SPWM) three-phase inverters, the peaks of common-mode (CM) voltage are so high that it will cause many negative effects. In this paper, a hybrid filter is presented to reduce the CM voltage (CMV) and the differential- mode (DM) harmonics in a three-phase inverter with carrier peak position modulation (CPPM). Because the use of CPPM strategy in the inverter can ensure that the output CMV will be only two levels in any condition, the simple active CM filter (composed of a half-bridge circuit) in the hybrid filter can effectively suppress the output CMV and CM current. The passive filter in the hybrid filter consists of an added single tuned filter and the original DM low-pass filter. The single tuned filter is designed to lower the DM harmonics, which are aggravated by the CPPM strategy in the carrier frequency band. Through the experiments, the validity of CMV and DM harmonics suppression by the hybrid filter in the three-phase inverter is verified and the calculation-control active CM filter is proved to be the best in the optional schemes.

Grid Harmonics Compensation Using High-Power PWM Converters Based on Combination Approach

Abstract: For high-power pulsewidth modulation (PWM) converters, selective harmonic elimination (SHE) modulation scheme is commonly adopted to reduce the low-order harmonics caused by a low switching frequency. However, the SHE scheme itself lacks the capability to actively compensate the grid background harmonics. To enable the active compensation ability of the SHE-modulated PWM converters, a selective harmonic compensation scheme and an SHE phase jittering method have been proposed in the previous works, and their effectiveness to actively attenuate the one grid line current harmonic was verified on a high-power PWM current-source rectifier (CSR) system application. Nevertheless, both the two methods have difficulty in compensating two harmonics simultaneously, which limits their applications with a low resonant frequency of converter system’s filter circuit. This paper extends the previous studies to enable the high-power PWM converters to actively compensate two grid background harmonics. The proposed method can not only further reduce the grid line current distortion but also make the application of the active compensation no longer limited by the filter circuit. The experimental results of its application on a high-power PWM CSR system are provided to verify the effectiveness.

A new passive filter design method for overvoltage suppression and bearing currents mitigation in a long cable based PWM inverter-fed motor drive system

Abstract: High-frequency pulse width modulation (PWM) in inverter-fed induction motor drive systems are widely used in industrial applications because of their flexible speed control and energy efficiency. However, high-frequency pulses induce overvoltage spikes to the motor via long cable. Such phenomenon would cause serious deterioration of the motor and cable. A passive overvoltage suppression techniques of low-loss “RL-plus-C” filter has been proposed recently. It has not only some merits of simple structure, low cost, and good robustness, but also a significant merit of low power dissipation. Based on the design method of “RL-plus-C” filter, this paper presents a new passive filter design method which can both eliminate voltage surges and greatly reduce inverter-induced bearing currents. The theoretical analysis and the design method are introduced in detail. Simulation results are good agreement with the theoretical analysis.

Advanced configuration of hybrid passive filter for reactive power and harmonic compensation

Abstract: Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. Simulation results show that performance of reactive power and harmonic compensation with advanced hybrid passive filter is better than conventional hybrid passive filters.

Variable resonant circuit and variable filter circuit

Abstract: PROBLEM TO BE SOLVED: To provide a variable filter circuit capable of obtaining a steep attenuation characteristic in the vicinity of the high frequency side of a pass band, and hardly complicating a circuit size and a control system even in a multistage formation.SOLUTION: A variable filter circuit 11 includes: a first resonator SAW1; a second resonator SAW2 connected in series with the first resonator SAW1; and a variable capacitor C1 connected in parallel with the first resonator SAW1. The resonant frequency of the first resonator SAW1 and the resonant frequency of the second resonator SAW2 are at the lower frequency side than the antiresonant frequency of the first resonator SAW1 and the antiresonant frequency of the second resonator SAW2. The antiresonant frequency of the first resonator SAW1 is between the resonant frequency and the antiresonant frequency of the second resonator SAW2.SELECTED DRAWING: Figure 1

Graphene-metal based tunable band-pass filters in the terahertz band

Abstract: The authors propose the concept, analysis, and design of frequency tunable band-pass filters operating in the terahertz band. The proposed structure is composed of two metal tapped line and five metal-contacted graphene hairpin resonators transferred onto a dielectric. This structure implements low insertion loss and frequency tunability by adequately controlling DC bias applied on the graphene. An efficient synthesis method has been presented, through combining classical microwave filter theory and the electrical properties of graphene. The theoretical and extracted resonance frequency of resonator (f 0), external quality factor (Q E) and coupling coefficient (Kij ) are utilised to determine the filter circuit dimensions. Then the authors proposed two examples with different operating bandwidths to validate the theoretical design. The potentially high losses of graphene is also evaluated.

Millimeter-wave bandpass filter using high-Q conical inductors and MOM capacitors

Abstract: This paper describes an efficient implementation of a lumped millimeter(mm)-wave narrow bandpass filter at 60 GHz. The mm-wave filter uses layout optimized conical spiral inductors which are shown to have higher quality factor (Q) and self resonant frequency values than standard spiral inductors. The filter also uses interdigital metal-oxide-metal capacitors which are shown to have Q values than nitride metal-insulator-metal (MIM) capacitors at these high frequencies. The filter is fabricated in 0.18 µm high resistivity RF silicon-on-insulator CMOS technology. The filter has a center frequency of 60 GHz and 3 dB bandwidth of 8 GHz, with a fractional bandwidth of 13.3% and a loaded Q of 7.5 occupying an area of (150×215)µm2. Monte-carlo simulations of the filter demonstrate excellent robustness against process variations due to usage of only two top thick metals and exclusion of MIM capacitors.

Current mode MOSFET-only third order Butterworth low pass filter with DTMOS tuning technique

Abstract: A new low-voltage, MOSFET-only, third order low-pass filter is proposed. The circuit employs only MOSFETs operating in saturation region. The transconductance gains and the parasitic gate to source capacitances of the MOSFETs represent resistive and capacitive elements of the filter. Using TSMC 0.18 µm technology parameters the circuit is simulated, non-ideal effects have been investigated and dynamic threshold voltage MOS tuning technique has been developed for the filter circuit to suppress the non-idealities. In this tuning technique, bulk terminals of MOS transistors are used to adjust the biasing point of the circuit by changing the threshold voltages of the MOS transistors. This gives the designers more flexibility than conventional tuning methods and allows low voltage operation when several transistors are stacked over each other. The resulting circuit is capable of operation at high frequencies with low power consumption due to the usage of significantly less number of transistors than conventional active block-based filtering circuits.

Passive filter design for periodic stochastic systems with quantized measurements and randomly occurring nonlinearities

Abstract: In this paper, the passive filter is designed for periodic stochastic systems with quantized measurements and randomly occurring nonlinearities. According to the dynamic properties of periodic systems, an N-periodic density quantizer is proposed to make full use of the communication capacity. By using Bernoulli processes, a new model is introduced to describe the randomly occurring nonlinearities, where each component of the state appears nonlinearity independently, and they influence each other based on the coupling matrices B(k). A reduced-order filter is designed to reduce the computation burden. Then sufficient conditions are established to ensure that the filtering error system is stochastically stable and satisfies the passivity. Finally, the effectiveness of the proposed new design technique is illustrated via a numerical example.

A new tunable SAW filter circuit for reconfigurable RF

Abstract: In recent years, the mobile data traffic is increasing and many more frequency bands have been employed in cellular handsets. A simple π type tunable band elimination filter (BEF) with switching function has been developed using a wideband tunable surface acoustic wave (SAW) resonator circuit. The frequency of BEF is tuned approximately 31% by variable capacitors without spurious. In LTE low band, the arrangement of TX and RX frequencies is to be reversed in Band 13, 14 and 20 compared with the other bands. The steep edge slopes of the developed filter can be exchanged according to the resonance condition and switching. With combining the TX and RX tunable BEFs and the small sized broadband circulator, a new tunable duplexer has been fabricated, and its TX-RX isolation is proved to be more than 50dB in LTE low band operations.

Electronically tunable fractional-order low-pass filter with current followers

Abstract: Proposal of a fractional (1+α)-order low-pass filter is presented in this paper. The proposed filter operates in the current-mode and it is designed using multi-output current followers (MO-CFs) and adjustable current amplifiers (ACAs). The filter possesses ability to electronically control its order and also the pole frequency. Verification of actual function of the filter is supported by the simulation results. The simulations were performed using Pspice simulator. The simulation results for three different values of its order and also three different values of pole frequency are illustrated and compared in this contribution.

On the design of LCL filter with passive damping in three-phase shunt active power filters

Abstract: This paper is focused on the LCL filter with damping resistance used to interface the shunt active power filter of an active DC-traction substation with the power supply. Two main requirements to be met by the interface filter are emphasized, in terms of significant attenuation of the current switching harmonics and ensuring the unalterated flow of the current to be compensated by active fitering. The behaviour of the LCL filter is analysed on the basis of frequency response associated to the currents-based transfer functions. First, the influence of the passive filter's parameters on the magnitude response is pointed out, resulting in useful aspects for a proper design. Then, the analysis of the damping resistance on the losses shows the existance of a maximal value of losses, when attenuation at switching frequency and maximal frequency to be compensated by active fitering are both imposed. Thus, the imposion of ratio between losses and maximal value of losses provides an additional condition leading to a concrete set of filter parameters. It is shown that there are practical limitations and a compromise must be made between the two requirements. The results of the Matlab/Simulink-based simulation of the active filtering regime of an active DC-traction substation with 12-pulse series diode rectifier and LCL coupling filter designed as proposed illustrate good performance of the system in terms of the LCL filter behavior.