LC Filter Design Research Articles

Design of LC Filter with Shunt Damping Resistor for Non-linear Load to Reduce the Total Harmonic Distortion in Load Voltage

The electrical power distribution system is the part of a power system, which supplies electrical power to consumers for utilization. Recently the utilization of nonlinear loads has been increasing in distribution system which badly affected the sinusoidal output voltage waveform. Every consumer of electricity demand consistent and sinusoidal voltage waveform to run their loads properly but due to power quality issues such as harmonics, voltage sag, voltage swell, flickering, and interruption of power supply which badly affect the output voltage of the loads may result in equipment damages, and financial loss. This research study discusses the voltage harmonic which is one of the power quality problems. The harmonic is a Non sinusoidal waveform that is generated due to the applications of nonlinear loads which affect the power system reliability, increase the transformer losses, line losses, and frequent faults are generated which results in poor utility revenue, and reduction in production in industries. So, in this research study, the LC filter with a damping resistor is designed to improve the output voltage waveform. The MATLAB simulation model is developed to analyze the performance of the distribution system under linear and nonlinear loads with and without an LC filter circuit and also THD% is analyzed through FFT.

LC filter optimized design considering the effect on the power converter and capacitor lifetimes

AbstractThis work presents an LC filter design methodology that considers the optimization of the converter as a whole: filter, semiconductor switches, and DC bus. The optimization is made in light of the system losses, volume, and the capacitors lifetime, discussing the advantages and disadvantages of decisions in the parametric design of the filter (of the values of L and C). The technology of components and construction challenges are considered in the design. The manuscript guides the design process of the filter in two steps: first, by providing the means to perform the parametric sweep of possible filter designs, according to the converter specifications and other restrictions; second, by describing how the hardware design is carried out and indicating the models and methods that are being used. Individualized analyses for each part of the converter system are made, and using the proposed methodology, three design examples are provided and analyzed, each choosing the filter parameters with different objectives: minimum volume, maximum capacitor lifetime, or maximum efficiency. Results show that using Kool M material results in the lowest filter volumes and losses. It is also shown that for the DC bus design, there is a compromise between volume and lifetime, with a greater number of capacitors increasing both attributes. By designing the system using the proposed methodology, the minimum volume is achieved at an operating point that differs from the individual minimum volumes of the filter and the inverter, and the lifetime is only 1.78% than the maximum lifetime point.

Multi-Objective Design of Output LC Filter for Buck Converter via the Coevolving-AMOSA Algorithm

Output LC filter is one of the most important parts for Buck converters. The existing optimization methods for LC filter fail to provide a fully optimized design. The difficulty in a holistic design approach lies in the trade-off relationships among different design targets. For example, smaller volume results in worse filtering capability and lower efficiency. To improve the overall performance of the output LC filter in Buck converter, a multi-objective design is proposed, taking the power loss, cut-off frequency and volume as design targets. This proposed holistic design approach utilizes Pareto-Frontier to achieve a compact LC filter with optimized efficiency and filtering capability. However, Pareto-Frontier generated by the previous multi-objective algorithms suffers from nonuniform or incomplete coverage, which seriously undermines design accuracy. Thus, the coevolving-AMOSA algorithm is proposed to provide a Pareto-Frontier with uniform and complete coverage. Via this proposed multi-objective design for the output LC filter in Buck converter with the coevolving-AMOSA algorithm, output LC filter can be flexibly designed to meet requirements in various applications while maintaining outstanding comprehensive performance. Optimal design cases for three specific application scenarios are presented as examples. Finally, the experimental results validate the effectiveness of the proposed multi-objective approach.

Design of 30 kW three-phase string inverter using simulink

This paper presents the design and simulation of a 30 kW DC to AC inverter. The inverter is designed based on the Zeverlution Pro 33K three-phase DC to AC inverter. Currently, there are 6 units of the inverters installed at 180 kW solar power plant located at Mukim Utan Aji, Perlis. So, in this paper, the results from the computer simulation will be compared to the site measurement conducted from this power plant. In this design, pulse with modulation (PWM) is used as the switching technique. Even though PWM offers the ease of LC filter design and low Total Harmonic Distortion (THD), the voltage amplitude of the sine wave output fails to achieve the required national grid parameters, i.e. 240 Vrms. To overcome this problem, a three-phase transformer has to be incorporated in the design to obtain the desired outputs. Results from computer simulation using SIMULINK show that the targeted AC parameters for all phases were achieved after comparing with the site measurement.

Advanced PWM Switching Technique for Accurate Unity Power Factor of Bidirectional Three-Phase Grid-Tied DC–AC Converters

Matrix-based high-frequency linked (MBHFL) bidirectional dc–ac converters are getting much interest in grid-tied applications due to their high efficiency and the compacted footprint. This paper proposes a new PWM switching technique of the MBHFL dc–ac converters based on phase shift angle considering compensation of the LC filter current at the grid side in order to realize accurate unity power factor and to reduce the total harmonic distortion (THD) of the grid current waveform. The proposed technique estimates the phase shift angle error between the grid voltage and current waveforms due to the capacitor injected current that reduces the power factor at the grid side. It considers two operational modes based on the patterns of three-phase grid voltage and current waveforms. Therefore, it provides the matrix converter switches with different duties according to the pattern of the detected grid voltage and the reference grid current to compensate the phase shift angle error. Also, grid LC filter design and the system controllable limit of the matrix converter output voltage are presented. In addition, the PWM switching technique of the H-bridge circuit is modified to realize safe operation of the converter during step changes at the grid voltage. The effectiveness of the proposed PWM switching technique and its related mathematical model have been investigated experimentally using laboratory prototype based 200 V, 2 kW.

Design of Photovoltaic Inverter Based on STM32 Microcontrollers

In this paper, the STM32 microprocessor is used as the central control core, and a 500W photovoltaic inverter is designed. The inverter adopts a two-stage conversion structure. The high-speed timer of the STM32 microprocessor generates high-resolution PWM and SPWM pulses and drives the first-stage DC/DC convertor after driving the chip through UCC27324 and IR2111 respectively. The rectification and the second-stage DC/AC inverter convert the DC signal into a utility frequency. In order to reduce the higher harmonics derived from the DC/AC inverter, the circuit also adopts the principle of LC filter design. Finally, in the Multisim simulation, the operation is stable. The error of the output AC voltage is controlled within 3%. It is said that the inverter has the advantages of high reliability, low harmonic content, and high efficiency.

Design Methodology for Three-Phase Buck-Type and Boost-Type Rectifiers to Comply With the DO-160G Current Distortion Test

The main standard for avionic equipment DO-160G defines a set of tests that require compliance before the employment of a device in aircraft. An important test involves the generator voltage and consequential current distortion of the three-phase load in the variable 360–800 Hz frequency grid. The main purpose of this paper is to present and analyze a systematic design methodology for three-phase boost and buck rectifiers in order to meet with the voltage distortion test requirement. For a given voltage harmonic profile, the current harmonic limits that have to be satisfied are translated into equivalent per-harmonic admittances and a profile of maximum rectifier input admittance versus frequency is obtained. The defined profile, due to normalization, is applicable to arbitrary power level with simple shifting by the base admittance governed by the converter nominal power. It is shown that for boost-type rectifiers there is a tradeoff between current controller bandwidth and input inductor size, while for the buck-type rectifiers main limitation lies in the input LC filter design used for differential electromagnetic interference filtering. The experimental results conducted on an SiC three-phase 10 kW VIENNA rectifier are tightly backing up the proposed theoretical analysis. This paper is accompanied by three videos demonstrating experimental measurement of d -axis open-loop duty cycle to inductor current transfer function, loop-gain of d -axis current controller with 3.8 kHz bandwidth and variable grid frequency 360–800 Hz operation of the converter under 0% and 10% input three-phase voltage total harmonic distortion.

A Technique for Tunable Filters with Low Insertion Loss and Narrow Bandwidth

A technique for tunable filters with low insertion loss and narrow bandwidth is proposed in the form of comb-line structure. Both resonant capacitor with pin-diodes and resonant inductance in the tunable filter were analyzed and the main source of insertion loss was obtained. A series of filters with same pin-diodes, center frequency, absolute bandwidth and low return loss was simulated. The results showed that, by changing the values of the resonant capacitor and inductance, insertion loss of the filter can be greatly restricted. This technique will allow the design of tunable LC filters with low insertion loss and narrow bandwidth.

Reliability-Oriented Optimization of the LC Filter in a Buck DC-DC Converter

Lifetime is an important performance factor in the reliable operation of power converters. However, the state-of-the-art LC filter design of a buck dc-dc converter is limited to the specifications of voltage and current ripples and constrains in power density and cost without reliability considerations. This paper proposes a method to optimize the design of the LC filters from a reliability perspective, besides other considerations. An enhanced model is derived to quantify the lifetime of the capacitor in the filter considering the electrothermal stress on it. Furthermore, the influence of different design aspects such as the value of capacitance, the value of inductance, and the type of the capacitor have been discussed, focusing on their impacts on the key design objectives, which are the cutoff frequency, lifetime, and volume. Based on the analysis, an optimized design is proposed among different parameter sets. A 1-kW converter prototype is applied to verify the theoretical analysis and simulation.

Design of Multiple Feedback Control Loops for a Single-phase Full-bridge Inverter Based on Stability Considerations

Single-phase inverters employ LC filters for the purpose of reducing pulse-width modulation harmonics. The drawback of LC filter is its stability problem at resonance frequency. Passive damping offers simple and reliable solution, but it decreases the overall system efficiency. Active damping is lossless and provides flexibility of controlling the damping performance; however, it is sensitive to parameters variation. This article presents stability analysis of a single-phase full-bridge inverter to improve dynamic performance and stability. Design of LC filter is carried out considering both undamped and damped structures. The effect of filter parameters on pole-zero locations of the inverter is presented, and variation of the phase margin over a wide range of parameters variation is examined. Active damping using closed-loop current control of the full-bridge inverter to mitigate the resonance oscillation is designed and compared with passive damping. The disturbance rejection via dynamic stiffness with and without active damping is examined to justify the proposed current controller. Simulation and experimental results are presented to validate the effectiveness of the proposed design. It is found that the proposed control of the inverter provides excellent voltage regulation with low total harmonic distortion and ensures good performance and robust stability under parameters variation.

DVR시스템에 사용되는 인버터부의 LC필터 설계와 피드백 성능분석

Voltage sags are considered the dominant disturbances affecting power quality. Dynamic voltage restorers(DVRs) are mainly used to protect sensitive loads from the electrical network voltage disturbances such as sags or swells and could be used to reduce harmonic distortion of ac voltages. The typical DVR topology essentially contains a PWM inverter with LC Filter, an injection transformer connected between the ac voltage line and the sensitive load, and a DC energy storage device. For injecting series voltage, the PWM inverter is used and the passive filter consist of inductor(L) and capacitor(C) for harmonics elimination of the inverter. However there are voltage pulsation responses by the characteristic of the LC passive filter that eliminate the harmonics of the PWM output waveform of the inverter. Therefore, this paper presented design and feedback performance of LC filter used in the DVRs. The voltage control by LC filter should be connected in the line side since this feedback method allows a relatively faster dynamic response, enabling the elimination of voltage notches or spikes in the beginning and in the end of sags and strong load voltage THD reduction. Illustrative examples are also included.

LC filter design for on-grid and off-grid distributed generating units

This paper deals with the design procedure of an LC-based output filter for three-phase inverters to be used in both off-grid and on-grid scenarios. The aim of this procedure is to provide guidelines and component selection criteria for reducing the inverter output switching ripple in order to limit the interaction with the control algorithm and to increase the filter stability. A suitable combination of resistive and reactive components is used to realize the complete filter structure. The proposed procedure is applied to the design of the output power filter for a 40-kVA three-phase inverter.

Galvanic Isolation and Output LC Filter Design for the Low-Voltage DC Customer-End Inverter

In this paper the need for a better design of the galvanic isolation and the output filter inductor in the customer-end inverter (CEI) of the low voltage DC (LVDC) network is discussed. The galvanic isolation can be implemented either with a 50 Hz transformer after the CEI or with an isolated DC-DC converter between the DC network and the CEI. However, the 50 Hz transformer solution adds a significant amount of volume and mass to the system. Based on calorimetric measurements conducted with the current system in which the galvanic isolation is implemented with the former method, the minimum requirements for the isolated DC-DC converter are presented and a comparison is carried out. For the system to be cost efficient the DC-DC converter should result in reduced lifetime cost compared with the transformer solution. In the output filter part a design method for an amorphous core filter inductor based on minimization of the lifetime cost is presented.

Filter Design Methodology and Application of GaN HEMTs in High-Frequency DC/DC Converter

ABSTRACTOptimization of the radio frequency (RF) transmitter performance in envelope tracking (ET) and envelope elimination and restoration (EER) techniques directly implies optimization of the envelope amplifier (EA) design. Since EA should have fast dynamic response together with high efficiency, synchronous buck is a suitable topology for this kind of application. The key issues for optimization of the converter design are the characteristics of the switching devices, the LC filter design, and the driving circuit for the switches. In this paper, design optimization of the LC filter for sinusoidal output voltage together with new technological solution for switching devices based on gallium nitride is proposed, while the applied drivers are commercially available ones, suitable for aforementioned GaN switches. Design of the output filter in synchronous buck converter for high-frequency application is important from two points of view: the first one is sufficient attenuation of the unwanted harmonics of the switching frequency so that envelope reference has minimum level of distortion and the second one is the overall impact of the filter design on the converter's efficiency. In order to increase the efficiency, the LC filter should be designed in a way to obtain compromise between the conduction and switching losses of the buck converter. In the case of sinusoidal output voltage, filter design parameter has been defined as the ratio between the maximum values of the inductor current and load current and power losses dependence on this parameter has been obtained. Theoretically obtained optimum design has been confirmed through experimental measurements, where four different designs were built and tested. On the other hand, application of new switching devices based on gallium nitride provided significant efficiency enhancement in comparison to Si MOSFETs and laterally diffused MOS transistors, due to the lower values of the gate charge and on-resistance. Tests with 64QAM and wideband code division multiple access (WCDMA) RF signals showed that these devices are the best choice for this kind of application, where the main challenge is to increase the efficiency of the signal transmission simultaneously with the bandwidth.

Parameter Optimization of the LC filters Based on Multiple Impact Factors for Cascaded H-bridge Dynamic Voltage Restorers

The cascaded H-Bridge Dynamic Voltage Restorer (DVR) is used for protecting high voltage and large capacity loads from voltage sags. The LC filter in the DVR is needed to eliminate switching ripples, which also provides an accurate tracking feature in a certain frequency range. Therefore, the parameter optimization of the LC filter is especially important. In this paper, the value range functions for the inductance and capacitance in LC filters are discussed. Then, parameter variations under different conditions of voltage sags and power factors are analyzed. In addition, an optimized design method is also proposed with the consideration of multiple impact factors. A detailed optimization procedure is presented, and its validity is demonstrated by simulation and experimental results. Both results show that the proposed method can improve the LC filter design for a cascaded H-Bridge DVR and enhance the performance of the whole system.

Analysis of the Input Harmonic Current of the Matrix Rectifier and the Design of its Input LC Filter

As a new type of pulse width modulate converter,the input current of matrix rectifier consists of a great deal of high-frequency harmony current. The harmony has a bad influence on the net side. So a input filter is needed to eliminate it. Through the approach of Fourier transform, the harmony wave of the matrix rectifier is discussed, and the conclusion of the value of high-harmony and the induction in inverse proportion is deduced. The inactive power that the capacitance absorbe determines its value. The range of the resonance frequency determine the range of the induction. From above analysis a basic design of input LC filter of matrix converter is given. The input filter has been verified in the matlab/simulink and good performances are achieved.

Application of genetic algorithm for the improved performance of boost converters

DC-DC Boost converters play a major role in DC-DC and DC-AC conversion applications like electric vehicle, integration of photovoltaic (PV) and distributed energy resources into the grid. When these converters operate they might introduce electromagnetic interference (EMI) and harmonics into the system. In order to avoid this, passive filters are prominently used. The methodology proposed here makes use of evolutionary computing algorithm in order to generate an optimized filter design for a boost converter. The proposed generic filter design procedure involves three steps, first selecting a suitable filter, second identifying the transfer functions involved, and finally using evolutionary algorithms to optimize the selected filter design. This methodology was implemented for LC filter design for a DC-DC boost converter using genetic algorithm.

無停電電源用PWM インバータの最適LC フィルタ設計

The design of the conventional LC filter has now all depended on trial and error. Therefore, the parameter designdŒsn’t meet our demands. To cover this issue the genetic algorithm is applied.This paper addresses LC filter design in PWM inverter of discrete-time model following control. A multiple-objective geneticalgorithm is used to benefit from computing. The pareto-optimal solution of LC filter is obtained. This algorithm has less possibility to be a local minimum. The pareto ranking method is used for adaptability of genetic algorithm. The validity ofanalysis is demonstrated by the comparison of resistance load to rectifier load. It suggests that the multiple-objective genetical gorithm is practical to optimize a parameter.

Optimal Design of Microgrids in Autonomous and Grid-Connected Modes Using Particle Swarm Optimization

The dynamic nature of the distribution network challenges the stability and control effectiveness of the microgrids in both grid-connected and autonomous modes. In this paper, linear and nonlinear models of microgrids operating in different modes are presented. Optimal design of LC filter, controller parameters, and damping resistance is carried out in case of grid-connected mode. On the other hand, controller parameters and power sharing coefficients are optimized in case of autonomous mode. The control problem has been formulated as an optimization problem where particle swarm optimization is employed to search for optimal settings of the optimized parameters in each mode. In addition, nonlinear time-domain-based as well as eigenvalue-based objective functions are proposed to minimize the error in the measured power and to enhance the damping characteristics, respectively. Finally, the nonlinear time-domain simulation has been carried out to assess the effectiveness of the proposed controllers under different disturbances and loading conditions. The results show satisfactory performance with efficient damping characteristics of the microgrid considered in this study. Additionally, the effectiveness of the proposed approach for optimizing different parameters and its robustness have been confirmed through the eigenvalue analysis and nonlinear time-domain simulations.

A Novel Filter Design for Output LC Filters of PWM Inverters

The cutoff frequency of the output LC filters of PWM inverters limits the control bandwidth of the converter system while it attenuates voltage ripples that are caused by inverter switching activities. For a selected cutoff frequency of an output LC filter, an infinite number of L-C combinations is possible. This paper analyses the characteristics of output LC filters for PWM inverters terms of the L-C combinations. Practical circuit conditions such as no-loads, full resistive-loads, and inductive-load conditions are considered in the analysis. This paper proposes a LC filter design method for PWM inverters considering both the voltage ynamics and he inverter stack size. An experimental PWM inverter system based on the proposed output LC lter design uideline is built and tested.