Abstract: Air quality has become a major public health issue in Asia including China, Korea, and India. Particulate matters are the major concern in air quality. We present the first environmental application demonstration of Ag nanowire percolation network for a novel, electrical type transparent, reusable, and active PM2.5 air filter although the Ag nanowire percolation network has been studied as a very promising transparent conductor in optoelectronics. Compared with previous particulate matter air filter study using relatively weaker short-range intermolecular force in polar polymeric nanofiber, Ag nanowire percolation network filters use stronger long-range electrostatic force to capture PM2.5, and they are highly efficient (>99.99%), transparent, working on an active mode, low power consumption, antibacterial, and reusable after simple washing. The proposed new particulate matter filter can be applied for a highly efficient, reusable, active and energy efficient filter for wearable electronics application.

Abstract: Current harmonics is one of the most significant power quality issues which has attracted tremendous research interest. Shunt active power filter (SAPF) is the best solution to minimize harmonic contamination, but its effectiveness is strictly dependent on how quickly and accurately its control algorithms can perform. This manuscript reviews various types of existing control algorithms which have been employed for controlling operation of SAPF. Harmonic extraction, DC-link capacitor voltage regulation, current control and synchronizer algorithms are examined and discussed. The most relevant techniques which have been applied for each control algorithm are described and contrasted in an organized manner to identify their respective strengths and weaknesses. It is found that the applied control algorithms differ in two conditions: (1) the condition where harmonic current distortion is treated by the SAPF in the presence of non-ideal source voltage; and (2) the condition where multilevel inverter is employed as the circuit topology of SAPF.

Abstract: This letter presents a three-phase voltage source inverter (VSI) topology to reduce the common mode (CM) voltage and electromagnetic interference (EMI) of electric motor drives. Instead of using filters, active or passive, or specific pulse width modulated (PWM) techniques to reduce the CM voltage, the proposed topology has inherently less CM voltage generation. With the addition of two switches placed in series on the dc lines, this topology effectively reduces the CM voltage during zero switching states by “floating” the inverter from the dc source. This topology can be implemented with any PWM method and does not add any additional complexity to the standard control techniques. The operation and CM reduction capability of the topology is first demonstrated in simulation and then verified with experimental results. A comparison of both common mode voltage and EMI is made to a conventional three-phase VSI to demonstrate the effectiveness of the proposed topology.

Abstract: Grid-connected converters (GcCs) employ LCL filters instead of simple L filters in order to meet new grid codes and their on-going changes in the near future. Active damping methods, without power losses, are preferred to passive ones for solving the resonance problems of LCL -filter-based GcCs ( LCL -GcCs). However, large changes in the grid inductance (typically under weak grid conditions and in rural areas) may compromise the system stability. Moreover, the delay of digital controllers will change system phase-frequency characteristics and consequently will affect the system stability. In view of this, this paper proposes a systematic design procedure for the active damping of voltage-oriented PI control for LCL- GcCs. The procedure considers active damping methods based on capacitor current feedback and is aimed to ensure stable operation under severe grid inductance variations while taking into account the influence of digital control delay and LCL filter parameters changes on the system stability. Simulation and experimental results are presented and discussed in order to validate the proposed design procedure.

Abstract: This paper proposes a novel high-order passive filter, i.e., series-parallel-resonant LCL (SPRLCL) filter, for single-phase half-bridge active power filters. The proposed SPRLCL filter consists of a series resonance introduced by adding a small inductor to the capacitor branch loop and a parallel resonance by paralleling a small capacitor with the gird-side inductor. Three design methods are proposed to fine tune the parameters of the SPRLCL filter. Design method I and method II enable the SPRLCL filter to attenuate more switching-frequency and double switching-frequency current harmonics than LCL or LLCL filters, while with design method III, the SPRLCL filter can be more robust against filter parameter variations. In order to achieve a better damping performance and facilitate the design of active damping control, the dominant resonance frequency of the proposed filter is set at one-third of the system sampling frequency. Based on this, a comprehensive parameter design process of the SPRLCL filter is presented, where the variation of source inductance is also considered. A proportional plus repetitive current-loop controller is designed to ensure system control stability and satisfactory harmonic compensation. Simulation and experimental results are finally presented to validate the feasibility of the theoretical analysis.

Abstract: The degradation in power quality causes adverse economical impact on the utilities and customers. Harmonics in current and voltage are one of the most commonly known power quality issues and are solved by the use of a hybrid series active power filter (HSAPF). In this paper, a new controller design using sliding-mode controller-2 is proposed to make the HSAPF more robust and stable. An accurate averaged model of a three-phase HSAPF is also derived in this paper. The design concept of the robust HSAPF has been verified through simulation and experimental studies, and the results obtained are discussed.

Abstract: High-frequency current harmonics injected into the point of common coupling, mainly at the switching frequency and its multiples introduced by the modulation of grid-connected converters, should be limited to comply with grid codes. This requirement can be satisfied by using trap filters with LC -traps tuned at the switching frequency and its multiples in replacement of conventional L filters. However, all existing trap filters are subject to certain problems, e.g., sensitivity to grid impedance variation and decreased high-frequency roll-off rate. In view of this, this paper presents a trap- LCL filter with its parallel resonant LC -trap located on the converter side, named as LT-C - L filter. The modeling and analysis presented in this paper show that the LT-C - L filter can be the most promising trap filter due to its advantages such as high roll-off rate, robustness against parametric variations of grid impedance and passive damper, satisfactory harmonic attenuation at the switching frequency, reduction of converter current total-harmonic-distortion, and flexible design of filter components through magnetic integration. A single-phase ac/dc grid-connected converter prototype has been built and tested in the laboratory, and experimental results are presented to verify the superiority of the proposed filter.

Abstract: In single-phase onboard chargers for electrified vehicles, second-order harmonic currents and corresponding ripple voltages exist on the dc bus. The low-frequency harmonic current is normally filtered using a bulk film capacitor or an additional active filter (AF) circuit. This presents an obstacle for improving the power density as well as reducing the cost. This paper proposes a simple and effective method that reduces the bulk capacitor in single-phase chargers and alleviates the low-frequency sinusoidal harmonic current in automotive applications. It applies the low-voltage (LV) battery charger auxiliary power module as an AF to filter the low-frequency harmonic currents in the high-voltage (HV) battery charger when the HV battery is charging. Hence, the integrated active filter auxiliary power module (AFAPM)-based dual-voltage charging system can achieve the AF function without extra power switches, heat sinks, and corresponding gate-drive circuits. In addition, the proposed AFAPM converter can obtain an almost unchanged switch rating to achieve 2.4-kW LV battery charging and 6.6-kW HV active filtering functions. Therefore, the proposed method can reduce the cost for the dual-voltage charging system in electrified vehicles. A 1.2-kW proof-of-concept prototype has also been built and experiments show promising results confirming the effectiveness of the proposed concept.

Abstract: In single-phase ac high-voltage (HV) battery chargers, as the input current is enforced to be varying sinusoidally in phase with the input voltage, the pulsating power at two times of the line frequency will be seen on the dc-link. Bulky capacitor bank or extra active filter (AF) circuits are needed to assimilate this harmonic current, which become a major barrier in terms of power density and cost. Sinusoidal charging method can be applied, while this might affect the charging efficiency and a deep study is still needed to further investigate on the impact to the Lithium-ion battery. An active filter auxiliary power module (AFAPM) based dual-mode dual-voltage charging system for vehicle application has been proposed. The AFAPM converter has two modes: the HV active filtering mode, in which the vehicle is connected to the grid and the converter assimilates the significant second-order harmonic current; and the low-voltage (LV) battery charging mode, in which the vehicle is running and the converter charges the LV battery from HV battery. However, a relay and inductors are still required in that converter to achieve the dual-mode operation. This paper proposes a primary full-integrated AFAPM for electrified vehicle applications with single-phase onboard chargers. The proposed AFAPM converter is composed of a two-phase bidirectional buck converter to work as an AF and a dual-active-bridge to operate as a LV battery charger auxiliary power module (APM). With the proposed converter, only an extra active energy storage capacitor is needed to achieve the active filtering. All the switches and inductors on the primary stage are shared between the AF and APM. Therefore, the use of a bulky capacitor bank or an additional AF circuit is avoided and, thus, the cost, size, and weight of the dual-voltage charging system in the electrified vehicle applications can be reduced. A 720-W prototype has been built to confirm the effectiveness of the proposed converter.

Abstract: High-order passive filters, such as the well-known LCL filters, are normally employed in the grid-connected power conversion systems to effectively attenuate the switching frequency harmonic introduced by the modulation of power converters. Although much more compact than the conventional single-inductor L filters, such passive filters are still bulky and expensive when compared with their active counterparts, e.g., the semiconductor switches. In order to improve the system power density and reduce its cost, the magnetic integration technique has been widely adopted so that the discrete inductors of passive filters are replaced by the integrated inductor, resulting in smaller magnetic cores and, therefore, the decreased volumes of passive filters. For conventional magnetic integrated LCL filters, the converter-side inductor and the grid-side inductor are integrated together and their coupling coefficient is intentionally minimized. In this letter, this coupling coefficient is fully utilized and properly designed, and the resulting coupling effect is equivalent to inserting an additional inductor into the filter capacitor branch loop. The integrated inductor and the filter capacitor can form an integrated LLCL filter, which exhibits the advantages of both the LLCL filter and magnetic integration, e.g., enhanced harmonic attenuation, reduced filter inductances, and system volume without adding the extra trap inductor. Finally, experimental results obtained from a single-phase grid-connected voltage-source converter interfaced by the proposed integrated filter are presented to validate its effectiveness.

Abstract: In this paper, an adaptive dc-link voltage controlled thyristor-controlled LC-coupling hybrid active power filter (TCLC-HAPF) is proposed for reducing switching loss, switching noise, and enhancing the compensating performance. Unfortunately, the TCLC-HAPF has both controllable active TCLC part and active inverter part; thus, the conventional minimum dc-link voltage calculation methods for active power filter (APF) and LC-coupling hybrid APF (LC-HAPF) cannot be directly applied to the TCLC-HAPF. Moreover, the aforementioned dc-link voltage calculation methods were developed based on the fast Fourier transform (FFT), which makes the calculation complex. This paper also presents a simplified minimum dc-link voltage calculation method for TCLC-HAPF reactive power and current harmonics compensation, which can significantly reduce the large amount of the calculation steps by using the FFT method. After that, an adaptive dc-link voltage controller for the TCLC-HAPF is developed to dynamically keep its operating at its minimum dc-link voltage level to reduce its switching loss and switching noise. Finally, representative simulation and experimental results are given to verify the proposed simplified dc-link voltage calculation method and the adaptive dc-link voltage control method of TCLC-HAPF.

Abstract: Due to the increase of power electronic-based loads, the maintenance of high power quality poses a challenge in modern power systems. To limit the total harmonic distortion in the line voltage and currents at the point of the common coupling (PCC), active power filters are commonly employed. This paper investigates the use of the multilevel modular converter (MMC) for harmonics mitigation due to its high bandwidth compared with conventional converters. A selective harmonics detection method and a harmonics controller are implemented, while the output current controller of the MMC is tuned to selectively inject the necessary harmonic currents. Unlike previous studies, focus is laid on the experimental verification of the active filtering capability of the MMC. For this reason an MMC-based double-star STATCOM is developed and tested for two representative case studies, i.e., for grid currents and PCC voltage harmonics. The results verify the capability of the MMC to mitigate harmonics up to the thirteenth order, while maintaining a low effective switching frequency and thus, low switching losses.

Abstract: This paper proposes a control strategy for a three-phase three-wire thyristor-controlled LC -coupling hybrid active power filter (TCLC-HAPF), which can balance active power and compensate reactive power and harmonic currents under unbalanced loading. Compared with TCLC-HAPF with conventional control strategy, active power filters and hybrid active power filters which either fail to perform satisfactory compensation or require high-rating active inverter part for unbalanced compensation, a control strategy was proposed for TCLC-HAPF to operate with a small rating active inverter part for a variety of loads with satisfactory performance. The control idea is to provide different firing angles for each phase of the thyristor-controlled LC -coupling part (TCLC) to balance active power and compensate reactive power, while the active inverter part aims to compensate harmonic currents. First, the required different TCLC impedances are deduced. Then, independent firing angles referenced to the phase angle of voltage across TCLC are calculated. After angle transformations, final firing angles referenced to phase angle of load voltages are obtained. In this paper, a novel controller for TCLC-HAPF under unbalanced loading is proposed. Simulation and experimental results are provided to verify the effectiveness of the proposed controller in comparison with a state-of-the-art controller.

Abstract: This paper proposes an isolated modular multilevel dc/dc converter (iM2DC)-based hybrid energy storage system (ESS) for shipboard MVDC grid application. The cell capacitors of the iM2DC are applied to implement the dc active power filter capability, which improves the MVDC bus power quality without auxiliary devices or sacrificing the battery lifetime. In addition, the proposed ESS achieves superior fault response with fault current limiting function, which benefits the fault localization and fast recovery. The operation principle of the proposed system is introduced first and the converter equivalent averaged model is derived. Then the multifunctional control method is presented, including the virtual-impedance-based ripple distribution strategy. Both offline simulation and controller hardware-in-the-loop test results are provided to validate the control strategy as well as the ESS performance.

Abstract: This paper presents design of electronically reconfigurable fractional-order filter that is able to be configured to operate as fractional-order low-pass filter (FLPF) or fractional-order high-pass filter (FHPF). Its slope of attenuation between pass band and stop band, i.e., order of the filter, is electronically adjustable in the range between 1 and 2. Also, pole frequency can be electronically controlled independently with respect to other tuned parameters. Moreover, particular type of approximation can be also controlled electronically. This feature set is available both for FLPF and FHPF-type of response. Presented structure of the filter is based on well-known follow-the-leader feedback (FLF) topology adjusted in our case for utilization with just simple active elements operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs), both providing possibility to control its key parameter electronically. This paper explains how reconfigurable third-order FLF topology is used in order to approximate both FLPF and FHPF in concerned frequency band of interest. Design is supported by PSpice simulations for three particular values of order of the filter (1.25, 1.5, 1.75), for several values of pole frequency and for two particular types of approximation forming the shape of both the magnitude and phase response. Moreover, theoretical presumptions are successfully confirmed by laboratory measurements with prepared prototype based on behavioral modeling.

Abstract: We know that the rise of harmonics is a major problem now days in non-linear loads. The universal use of non-linear loads like in power electronics equipment which amplified the harmonic-related difficulties in service and trade power systems this make an essential requirement of filter. The nonlinear loads be compensated & sometime we can identified but sometimes they include their own non characteristic harmonic portion & not ideal as it is actual in input & voltage sag occur so many times in a day. As increasing the harmonic magnitude component contribution of key problem also rises in industrial sector, so this is a very complex in power system, to overcome we using different methods to reduce this major problem. This paper is presents a proposed model of passive Alter & combination of shunt active & passive filter to reducing harmonic limits in single-phase system as tracked by IEEE std. 519-1992.

Abstract: Cascaded multilevel converter (CMC)-based energy storage system, which consists of cascaded H-bridge converters and energy storage components, is a promising option to compensate fluctuating electric power of renewable energy. This paper proposes a novel single-phase CMC-based battery storage system, which includes an LC branch. The cascaded converter cells and the LC branch form an auxiliary power loop, which could realize active power exchange between different cells with the proposed dual-frequency phase-shifted carrier pulse width modulation (DF-PSC PWM). The principle and effectiveness of DF-PSC PWM and the power transfer mechanism are analyzed. Meanwhile, the design of the tuned filter, output filter, and the state of charge balancing control system is introduced. The operation principle of the power exchange in the proposed energy storage system has been successfully verified by simulation and experimental results.

Abstract: In this study, a cascade two-loop non-linear controller is developed for single-phase shunt active power filters which is robust and stable in a wide range of output current and DC-link voltage changes. A variable structure proportional-integral controller is designed to regulate DC-link voltage in the outer loop. Also filter output current is controlled in the inner loop using adaptive backstepping approach. All of the model uncertain parameters are estimated using designed estimation rules. By introduction of suitable Lyapunov functions, proposed controller stability is investigated using Barbalat lemma. Grid reference current is calculated indirectly using a phase-locked loop circuit according to DC-link voltage error. Designed active power filter has been implemented using TMS320F28335 digital signal processor and practical response of the developed controller is studied in some tests. It is shown that the proposed controller is able to eliminate harmonic components of the local load current with a fast dynamic response. Also, compensation capability of the designed non-linear approach is compared with sliding mode controller in similar conditions.

Abstract: In this paper, a variation-aware and reliable design of a fully integrated radio frequency (RF) bandpass filter realized using a voltage differencing transconductance amplifier is presented. The filter is characterized by its high frequency operation, low power consumption, high quality factor, and it is insensitive to process, voltage, and temperature variations. Sensitivity analysis has been performed to analyze the circuit performance in the presence of parasitics. The inductor-less approach finds its application in integrated building blocks of RF front ends, thus eliminating the requirement of off-chip filters in transceivers. Centered at 2.511 GHz and operating within the 36.21 MHz 3-dB bandwidth, the filter draws 0.168 mA from a ±1 V power supply, attains a voltage gain of 72.6 dB, a quality factor of 69.34 and noise figure of ~29.6 dB. In addition, it has a dynamic range of 125.84 dB-Hz and a 1-dB compression of −1.5 dBm which translates into a figure of merit as high as 94 dB.

Abstract: This paper presents a fast selective harmonic current mitigation strategy for inverters with active power filter capabilities based on synchronous reference frames and two degrees-of-freedom internal model controllers. The advantage of this control strategy over the conventional proportional integral (PI) control solution is a significant increase in the speed of harmonic detection and mitigation. Furthermore, this control strategy reduces the computational burden when applied in a digital controller. These characteristics make this strategy desirable for applications, where fast/harmonic detection and mitigation are needed. Mathematical analysis and simulations are presented to corroborate the performance of the proposed controller strategy. Finally, the results of this proposal are verified in a 1 kW three-phase multifunctional inverter with harmonic compensation capabilities up to the 17th harmonic.

Abstract: Now-a-days, decadence of power quality is foremost issue of electrical society. In practice, utility of switching device is increased in industrial as well as in domestic applications. Non-linearity causes adverse effects on system efficiency, utility of the power supply, power factor, etc. As reduction in power factor increases reactive power which does not have any contribution in energy transfer so its compensation is needed. So efforts are made to upgrade power quality, concept of Filter is in demand. In contrast to passive filter, active filters are popular due to its smaller size and weight. In this paper, work is done on shunt active power filter (SAPF) using P-Q theory for current harmonic mitigation and reactive power compensation. Here the simulation as well as its parameters, with or without active filter is well presented. We commence the paper with power quality issues then better understanding of PQ theory, simulation circuits, results, comparison and finally ended with conclusion. An effort is made to achieve THD value of source current below 5% to meet the required IEEE standards.

Abstract: In this paper, a new modeling and parameter design method for the thyristor-controlled LC -coupled hybrid active power filter (TCLC-HAPF) is proposed, which includes the analysis of the inner flowed three-phase unbalanced power during unbalanced condition. Different from the conventional method which ignores the inner flowed three-phase unbalanced power, the proposed design method can achieve better performance during unbalanced compensation. To verify the validity and advantages of the proposed modeling and parameter design method of TCLC-HAPF, the mathematical analysis, representative simulation and experimental results for compensating different unbalanced loading situation are presented in comparison with the conventional design method.

Abstract: Detecting and locating the fault of IGBT rapidly and accurately are the keys to ensuring the security and reliability of the active power filters (APF) system. A fault diagnosis algorithm based on the mathematical model of ac side output voltages for three-phase four-wire three-leg two-level shunt APF is proposed in this paper. According to the different relationships between the APF's ac side output voltages and turn-on duty cycle of the corresponding IGBT under normal condition and fault condition, the fault diagnosis algorithm can detect and locate the open-circuit (OC) faults with no additional hardware or sensors required. All the signals used in this algorithm have already been employed in the APF stem controller. All possible OC fault conditions can be detected and located quickly and reliably by the algorithm. In addition, the algorithm is highly free from the load changes and can be used during the dynamic process of load changes. The efficiency of the proposed algorithm, under single and multiple faults conditions, is verified by the simulation and experimental results.

Abstract: Recently, Electric power quality has become significant in the both power suppliers side and end user side. The electrical power system polluted because of non-linear loads used in the system. Utilities always looking for cost effective and improved power quality (PQ) solutions. Initially, the conventional method of passive filtering enrich to mitigate the PQ problems. The inadequate performance of the conventional passive filter techniques to mitigate PQ problems has affirm to introduce advanced power electronic based topologies in the improvement of PQ. Shunt active power filter (APF) is well established to mitigate PQ problems like current harmonics, reactive power demand and poor power factor in the distributed electrical power system. This study gives a brief review on shunt APF configurations for single-phase (two-wire), three-phase three-wire (3P3W) and three-phase four-wire (3P4W) systems and compensation control techniques for sinusoidal and non-sinusoidal voltage supply conditions. Additionally, latest improvements, practical aspects of implementation and some future research fields to carry out in the field on shunt APF.

Abstract: This paper proposes a new control algorithm for mitigation of power quality problems at the distribution level. The control algorithm is designed on the basis of echo-state network, which is a type of recurrent neural network. This technique is used to extract fundamental weight components from nonsinusoidal load currents. These weight components are used to evaluate reference grid currents and consequently generate switching logic for the voltage source converter used in the active filter. The shunt-connected active filter with the proposed control algorithm is used to overcome several current-related power quality problems and provides the load compensation. Problems such as the presence of lower order harmonics, insufficient reactive power, and load unbalancing are corrected using a shunt filter in both the power factor correction and voltage regulation modes. The proposed control algorithm is validated on a real time system which is a prototype of a shunt filter. The algorithm is tested in MATLAB using Sim Power Systems and SIMULINK and implemented on a digital signal processor.

Abstract: This paper deals with the design of low-power high-performance continuous-time filters. The proposed operational transconductance amplifier architecture employs current-reuse differential difference amplifiers in order to produce more power-efficient ${G}_{{m}}{-}{C}$ filter solutions. To demonstrate this, a sixth-order low-pass Butterworth filter was designed in a 0.18- $\mu\text{m}$ CMOS, achieving a 65-MHz −3-dB frequency, an in-band input-referred third-order intercept point of 12 dBm, and an input-referred noise density of 40 nV/Hz1/2, while only consuming 8.07 mW from a 1.8-V supply and occupying a total chip area of 0.21 mm2 with a power consumption of only 1.19 mW per pole.