Active Filter Topology Research Articles

Fault tolerant shunt active power filter: topology reconfiguration using optimised fault detection algorithm.

This paper proposes a fault tolerant shunt three phase active filter topology. It mainly details converter reconfiguration and examines a fast and reliable optimised fault diagnosis method. This method avoids spurious semi conductor fault detection due to semi conductor switching. The converter topology is based on classical three-leg active power filter topology but includes bi-directional switches for converter reconfiguration after fault detection. The resulting post fault power structure is a two-leg topology with fault leg connected to the middle point of the filtering capacitor. A new fault diagnosis method is proposed, based on classical voltage measurements. It includes combinatory logic to analyse and validate error signals. An unique control is applied before and after fault detection, which avoids any controller reconfiguration. Simulation results obtained with Saber CAD tools validate the theoretical study and the modelisation.

A New Hybrid Active Power Filter Topology Enabling Low Voltage Switching Devices and Storage Capacitors.

The increasing importance of mains harmonic content has been responsible for several improvements in Active Power Filter topologies in the last decade. The pure multiple half-bridge configurations are now becoming replaced by new hybrid topologies, aiming to be simultaneously less bulky and expensive. This new technique consists in reducing the voltages at the storage capacitors and consequently at the switching devices. This is achieved by introducing an extra filter between mains and the power electronics converter, tuned at the interest frequencies. This paper presents a new topology for parallel hybrid active filters that can reduce the converter voltage down to 5% of the mains voltage magnitude. A simple, comparative study will be presented, taking in consideration some topologies previously proposed by other authors.

Suppression of over voltage in SiC-based inverter fed induction motor

ABSTRACT Silicon carbide (SiC) based inverters are widely used due to their fast switching and ability to withstand high temperatures and Voltage. This helps to increase efficiency and reduces switching losses compared to the silicon-based inverter. However, this fast-switching device causes an increase in the Voltage at the junction of the cable and motor due to the reflected wave. The main causes of overvoltage are cable/motor impedance mismatch, fast-switching inverter devices (IGBT), and inverter-motor separation. To extend the induction motor lifespan, overvoltage reduction is necessary. Passive and active filters solve the problem, but passive filters are bulky and have high power loss. This paper presents a shunt active filter approach for an inverter-fed induction motor to reduce overvoltage. To show the effectiveness of the proposed approach, the findings were compared to the topology of the clamp-type active filter already in use. The shunt active filter used Proportional Integral (PI) and fuzzy controllers to generate reference current according to the Synchronous Reference Frame (SRF) theory. Harmonics in the power system were removed using the SRF theory. The unique aspect of this work is how the reference current is produced in the shunt active filter using the SRF theory. The proposed shunt active filter with a fuzzy controller was added to the hardware implementation to achieve better results than previous active filters.

A Fusion Topology of Higher Efficiency and Lower Capacity Hybrid Parallel Multi-Converters for Power Quality Compensation

In high-power applications, different multilevel voltage source converter (VSC) topologies are usually applied. The hybrid parallel multiconverters, which is a combination of multiactive and hybrid VSCs connecting in parallel, can be a promising solution in a high-power grid. In this article, the fusion VSC topology concept is proposed in which fusion VSC takes the advantages of both active (inductive coupling) VSC and hybrid (capacitive coupling) VSC. It corresponds to overcoming the insufficient-capacity problems when active VSCs are employed alone and vice versa. This article proposes fusion active power filter topology by combing active and hybrid power VSC through their equivalent model for power quality compensation. With the proposed VSC's equivalent model, it can reduce the converter rating by 17%–80% compared with the conventional approaches. Additionally, the corresponding control algorithm is proposed for the FAPF for power quality compensation. Finally, the simulation and real-time digital simulator hardware-in-the-loop experimental results of the proposed FAPF topology are given to demonstrate the validity and effectiveness for reducing its capacity and power loss compared with the conventional multi-VSC in power quality compensation.

Analysis of current harmonics compensation using various active filter topologies

The technological requirements in the industrial and domestic sectors greatly depend on the sensitive and controllable electrical and electronic equipment to meet the application-specific demands, the usage of these nonlinear devices inherently contribute to the degradation of electric power quality, among the various power quality disturbances, Harmonics, which significantly contribute to the waveform distortion has gained the attention among the researchers due to its negative impact on the entire power system network. Hence, the suppression of harmonics has been the focus area in the present context. The paper presents an overview on circuit configuration of three active power filter topologies, delta connected Shunt active filter, Delta-connected Fixed Capacitor Thyristor Controlled Reactor (FCTCR) and delta connected Hybrid filter. Paper also investigates the effectiveness of instantaneous active reactive power theory, Synchronous reference frame theory And Adaptive detection algorithm as control strategies for the suppression of the harmonics under different power system network conditions. Results of the simulation studies are presented in the paper to assess the performance of designed filter with different control strategy for the mitigation of current harmonics in the proposed power system network, simulation studies are carried out using MATLAB/SIMULINK.

Reconfigurable Non-Foster Elements and Squint-Free Beamforming Networks Using Active Transversal Filter-Based Negative Group Delay Circuit

A new type of reconfigurable negative group delay (NGD) circuits based on active transversal filter topology is introduced in this work. By incorporating varactors with the NGD circuit at the input and output ports of active transversal filter based on distributed amplifiers (DAs), one can notably enhance the tunability for both amplitude and phase responses, thereby enabling NGD characteristic synthesis with a wider reconfigurable range. In this article, the proposed reconfigurable NGD circuits are applied to create both tunable non-Foster elements and tunable squint-free beamforming networks, which are verified by experiment. Furthermore, a general <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -stage transfer function for the proposed reconfigurable NGD circuit is derived, in which a two-stage particular case is given as an illustrative proof-of-concept example. Based on the reconfigurable NGD circuits, a prototype of a tunable negative capacitor is fabricated and measured, of which the capacitance can be tuned from −1.0 to −4.0 pF over a bandwidth of 100 MHz at 1 GHz or around 10% relative bandwidth. In addition, such an NGD circuit is utilized to create a low-dispersion superluminal transmission line, which enables a reconfigurable series antenna feedline for squint-free beam steering. Experimental results show that the main beam of the NGD antenna array has a tuning range from −15° to 15° within a squint-free bandwidth of 100 MHz at 2 GHz or within a relative bandwidth of around 5%.

A compound control strategy for LCL-based three phase four leg shunt active power filter

Conventional single inductor filter which is applied to three-phase four-leg shunt active power filter hardly meet the requirements for high frequency harmonic suppression. LCL filter has advantage both in high dynamic response and high frequency harmonic suppression. Repetitive control can realize accurate tracking of multi-harmonics signal. However, the design of corrector for repetitive control is mostly complicated. This paper proposes a topology of three-phase four-leg shunt active power filter based on LCL filter and improve its stability through capacitive current feedback. Compound control strategy which includes PI control and repetitive control is adopted to improve the compensation effect of harmonic current. Corrector for repetitive control has simple structure and is easy to design. The conventional PI control and compound control are compared and analyzed in detail. Moreover, the difference of property between LCL filter and single inductor filter is compared and analyzed. Simulation results show the correctness and effectiveness of the designed LCL filter and the proposed compound control strategy. The proposed method provides a reference for making three-phase four-leg shunt active power filter more practical.

DRLA: Dimensionality ranking in learning automata and its application on designing analog active filters

In this paper, a learning automata (LA) method is introduced based on dimensionality ranking (called DRLA), and its application for designing analog active filters is investigated. The basic idea in the DRLA is that the number of iterations and ordering selection of dimensions for the next phase is according to effect of each dimension in the fitness improvement of the current phase or previous phases. This strategy improves the exploration of search space and escaping the local minimums. Also, to achieve the proper balance in exploration and exploitation, the control parameter τ is changed by a linear control manner. To validate the applicability, accuracy, and performance of the proposed approach, it is first evaluated on 23 benchmark functions and then, as a new application of LA, applied to the optimal design of two different analog active filter topologies as real-world engineering problems. The filter component values are estimated within E96 series for resistors and capacitors, and a single-objective function is also considered as average quality factors deviation and cut-off frequency deviation. Simulation results compared to some rival single-objective metaheuristic optimization methods reveal that the improved method has competitive performance in terms of fitness, convergence, statistical analyses, box plot, and bode curve as well as runtime.

Lossy Microwave Filters With Active Shape Correction

Obtaining the prescribed microwave filter response is highly desirable for proper frequency selectivity in RF transceivers. As the traditional microwave filter design methods do not take into account finite unloaded quality factors, lossy resonators cause significant deviations from the prescribed filter response, especially in filters with narrow bandwidths or of high orders. This deviation gets more severe as the resonator losses increase. Building on the lossy filter design techniques by using an active shape correction mechanism, this paper proposes a new approach to recover the filter response when the filter has moderately-to-highly lossy resonators. Being different than most active filter topologies, where all of the resonators are loss-compensated, this study aims at achieving the shape correction with $N-2$ active elements. To characterize the design, a novel lossy-active coupling matrix is introduced by extending the $(N+2) \times (N+2)$ lossy coupling matrix. The proposed theory is verified with the design and fabrication of two $3^{rd}$ order 5 % bandwidth filters operating at 1 GHz and employing resonators with quality factors of 100 and 28, respectively. It has been shown that the method can recover the response in both designs and the theoretical and measured responses are in good agreement.

High-Frequency Low-Current Second-Order Bandpass Active Filter Topology and Its Design in 28-nm FD-SOI CMOS

Fully Depleted Silicon on Insulator (FD-SOI) CMOS technology offers the possibility of circuit performance optimization with reduction of both topology complexity and power consumption. These advantages are fully exploited in this paper in order to develop a new topology of active continuous-time second-order bandpass filter with maximum resonant frequency in the range of 1 GHz and wide electrically tunable quality factor requiring a very limited quiescent current consumption below 10 μA. Preliminary simulations that were carried out using the 28-nm FD-SOI technology from STMicroelectronics show that the designed example can operate up to 1.3 GHz of resonant frequency with tunable Q ranging from 90 to 370, while only requiring 6 μA standby current under 1-V supply.

Assessment of Active and Hybrid Power Filters Under Space Vector Modulation

Previous researches on space vector modulation (SVM) in active power filters (APFs) topologies find that compared with sinusoidal pulse width modulation, the SVM offers a better harmonic spectrum and has 15.47% more voltage utilization. The article not only proposes SVM for hybrid active power filters (HAPFs) but also answers the following questions. 1) Under what conditions both filters are equivalent to one another? 2) Which filter can enhance better tracking ability and better performance? 3) How the coupling component parameters and dc voltage affect the performance of both filters? The representative simulation and experimental results are given to verify the discussions. The conclusions can be application guidelines for the design of inductive and capacitive coupling inverters (e.g., APFs and HAPFs) in smart grids and development of energy internet due to their generalities to applications.

Research on three-phase four-wire active power filter based on LCLCL coupling structure

In this paper, the main circuit topology of the three-phase four-wire active power filter (APF) and its harmonic current detection and control algorithm are studied. An active power filter system combining LCLCL filter and a three-phase H-bridge structure is proposed. This paper has applied harmonic detection algorithm based on an improved synchronous phase-locked loop (SRF-PLL) and recursive discrete Fourier transform (RDFT) while using triangular carrier modulation control based on PI adjustment to realize the harmonic compensation of the power filter to the grid current. The system has a notch effect on the harmonic at the switching frequency. It can detect the fundamental component and each harmonic component of the load current separately with a small amount of calculation, good real-time performance. Finally, a 5KVA single-phase APF prototype was built to test the superiority of the main circuit topology and the algorithm of current detection and control.

An Area-Efficient and Highly Linear Reconfigurable Continuous-Time Filter for Biomedical Sensor Applications.

This paper proposes a compact, high-linearity, and reconfigurable continuous-time filter with a wide frequency-tuning capability for biopotential conditioning. It uses an active filter topology and a new operational-transconductance-amplifier (OTA)-based current-steering (CS) integrator. Consequently, a large time constant , good linearity, and linear bandwidth tuning could be achieved in the presented filter with a small silicon area. The proposed filter has a reconfigurable structure that can be operated as a low-pass filter (LPF) or a notch filter (NF) for different purposes. Based on the novel topology, the filter can be readily implemented monolithically and a prototype circuit was fabricated in the 0.18 μm standard complementary-metal–oxide–semiconductor (CMOS) process. It occupied a small area of 0.068 mm2 and consumed 25 μW from a 1.8 V supply. Measurement results show that the cutoff frequency of the LPF could be linearly tuned from 0.05 Hz to 300 Hz and the total-harmonic-distortion (THD) was less than −76 dB for a 2 Hz, 200 mVpp sine input. The input-referred noises were 5.5 μVrms and 6.4 μVrms for the LPF and NF, respectively. A comparison with conventional designs reveals that the proposed design achieved the lowest harmonic distortion and smallest on-chip capacitor. Moreover, its ultra-low cutoff frequency and relatively linear frequency tuning capability make it an attractive solution as an analog front-end for biopotential acquisitions.

An Improved Salp Swarm Algorithm With Spiral Flight Search for Optimizing Hybrid Active Power Filters’ Parameters

In view of various issues occasioned by harmonic pollution in the power system, the optimization of the filter parameters is of great significance. However, under the system constraints, estimating the filter parameters accurately and reliably is a challenging task. To complete this task, this paper proposes an improved salp swarm algorithm based on the spiral flight search strategy (ISSA-SFS), which rationally integrates the spiral flight search (SFS) strategy, the multiple leader (ML) strategy, and the random learning (RL) strategy with two improved evolution phases: the improved lead phase (ILP) and the improved follow phase (IFP). In the ILP, the SFS strategy is introduced to enhance the global search capability and avoid premature convergence. Furthermore, in the ILP, an ML strategy is proposed to select multiple leaders, further strengthening the global search capability of the proposed algorithm. In the IFP, a simple RL strategy is developed to learn two different random individuals, efficiently improving the local exploitation. The proposed algorithm ISSA-SFS is applied to optimize two prominent hybrid active power filter (HAPF) topologies, and each topology contains four different study cases. The overall experimental results indicate that the ISSA-SFS is a more promising alternative to achieve the optimal design of HAPFs compared with other well-established algorithms, especially in terms of accuracy and robustness.

Suppression factor as evaluation criterion for wide‐frequency filtering equipment

Here, a novel harmonic suppression performance criterion, namely suppression factor (SF), is suggested for the wide-frequency power filtering equipment. Performances of single-tuned passive filter, combination of passive filters tuned to various frequencies, shunt active power filter (APF), and a shunt hybrid active power filter (HAPF) topologies have been evaluated considering their SF values over a defined frequency range. Moreover, effect of the control method for the active filtering equipment on SF values is also analysed by comparing both theoretical and the experimental results. The frequency range of harmonics to be suppressed is chosen using the field measurements of Induction melting furnace (IMF) load, one of the most problematic loads in terms of interharmonics, and a field implemented HAPF system is used for the experimental verifications.

Three-level (NPC) shunt active power filter topology for harmonic reduction using different control strategies

Three-level (NPC) shunt active power filter topology for harmonic reduction using different control strategies

Optimal design of analog active filters using symbiotic organisms search

AbstractThis paper investigates the optimal design of analog active filters using the symbiotic organisms search (SOS) algorithm. Symbiotic organisms search is a newly proposed global optimization method that is inspired by the symbiotic interaction strategies between different organisms in an ecosystem. In SOS, the 3 common types of symbiotic relationships (mutualism, commensalism, and parasitism) are modeled using simple expressions, which are used to find the global minimum of the fitness function. Unlike other methods, SOS is free of tuning parameters, which makes it an attractive optimization method. Here, SOS is used to determine the values of the passive components (resistors and capacitors) used in active filters. Two active filter topologies, fourth‐order Butterworth low‐pass filter and second‐order state variable low‐pass filter, are considered. The components values are chosen from several standard industrial series (E12, E24, and E96). The results obtained using SOS are compared with those obtained using several optimization methods, like particle swarm optimization, seeker optimization algorithm, differential evolution, and other ones. It is shown that the SOS is a robust straightforward evolutionary algorithm that can outperform other well‐known methods.

Design of a Dual-Band Bandpass Filter Using Active Inductor Principle

A new topology of a dual-band active bandpass filter is presented in this paper. This structure consists of two transconductances constituting the active inductor, which represents the core of the filter and which is responsible for delivering the resonance frequency of the filter, connected at its input to a varactor used to tune the centre frequency. The two peaks of the dual-band filter can be tuned in frequency while maintaining the same power of gain and the same bandwidth. Good out-of-band rejection is observed of -13 dB and -11 dB on both bands with a very high quality factor that exceeds 1500.The filter is designed for 5G applications around 28GHz and 38 GHz and for satellite uplinks.

Design and modeling of SMES based SAPF for pulsed power load demands

In this article, a Superconducting Magnetic Energy Storage (SMES) based Shunt Active Power Filter (SAPF) topology is proposed to compensate high power pulsating load demands in a power system. The SMES based SAPF is designed and modeled to realize as an efficient compensator for the compensation of pulsed power load demands. The conventional SAPF is efficient to mitigate the power quality problems in a power system unless there is high power pulsating load demands, transient conditions or power fluctuations. Particularly, a Modified Synchronous Reference Frame (MSRF) control algorithm has been implemented to generate proper switching signals for the three-phase Voltage Source Converter (VSC) of the SMES based SAPF. In the simulation, it has been seen that the SAPF is incompetent under high power pulsating load demands whereas the SMES based SAPF has shown excellent performance under such load conditions. Moreover, a comparative analysis has been made between the conventional SAPF and the SMES based SAPF under pulsating load conditions, to check the effectiveness of the SMES based SAPF. The performance of the proposed system is presented by using Sim Power System (SPS)/MATLAB Simulink and real-time digital simulator laboratory (RTDS-Lab).

Sallen-Key Topology, MFB and Butterworthy in Bandpass Design for Audio Circuit Design

This paper succinctly studied active filter topologies: Sallen-key circuit, MFB and Butterworth in band pass design for audio circuits. It has been able to identify distinctive suitable features with applications in audio frequencies range. The work also serves as a foundational study for an advanced work on active audio filters. Sallen-Key pluses with quality factor (Q) that can be varied via the inner gain (G) without modifying the mid frequency (fm). Notably, the Q and Am cannot be adjusted independently. Butterworth, maximally flat magnitude response in the pass band, has monotonic amplitude response with an excellent flat pass band, less phase shift, and better transient results.