Passive Power Factor Correction Research Articles

Recent advances in single-phase rectification methods

With the increasing number of population, people are increasingly dependent on electricity. In recent years, more and more public transportations like bus, taxi take the mode of pure electric. The function of rectifier is to transform the AC current into DC current, which is a significant research direction in electrical industry, especially in power electronic technology. In our nation, the national grid supplies 220V 50Hz AC to residence, it is a voltage pattern that varies periodically. Due to the lower loss of power during long-distance transmission, it has become the basic mode of power transmission and supply in the world. In usual production and our daily life, we frequently need DC (such as: mobile phones, flashlights, computers, charging piles for electric vehicles, etc.), so rectifier has become a heated research part. At present, more and more researches are based on power electronic technology, design all kinds of rectifier circuit by using the between conductor and insulator property of semiconductors. This essay provides an overview of single-phase rectifier circuits (including half-wave rectifier, full-wave rectifier, and bridge rectifier) and passive power factor correction.

Empirical Investigation of a Single-phase Input Switched AC-DC Boost Converter with Improved Power Quality

The Boost converter topology is most widely used for power factor correction (PFC) converters. The conventional passive Boost PFC converter inherently suffers from the lack of controllability and non-ideal characteristics of the diode-bridge rectifier. Replacing diodes with active switch(es) offers viable solutions but increases the circuit complexity. Addressing this trade-off, a novel design of a single–phase input switched AC to DC Boost converter has been presented in this article. The active switch of the Boost DC converter is shifted to the input side of the full-bridge diode rectifier which provides more control on the input current without increasing much of the circuit complexity. Two Boost inductors and two output split capacitors are used for providing higher step-up operation compared to the conventional. The converter has been simulated both in open-loop and closed-loop conditions using the PSIM software. The simulation results show that the proposed converter provides good dynamic response and can maintain a constant stable output voltage during sudden load change. Furthermore, to evaluate the experimental performance of the suggested converter, a prototype converter has been developed. A scaled-down experiment has been performed which shows that the converter can achieve up to 85.2 % efficiency and an input power factor of 0.9.

Evaluation of the Perspective Power Transistor Structures on Efficiency Performance of PFC Circuit

The aim of this work is to investigate the influence of circuit elements on the properties of the selected power factor correction (PFC) topology. Active or passive PFC serves to increase the power factor (PF) and reduce the total harmonic distortion (THD) of the mains current. As a result, the distribution network is lightened due to its interference caused by connected electronic devices. An important indicator of all electronic converters is efficiency. Therefore, the work deals with the analysis of possible efficiency improvements in conjunction with the use of technologically new active components. Detailed experimental analyses and optimization procedures are performed in terms of the influence of transistor structures (SiC and GaN) on the qualitative indicators of the proposed PFC converter for a wide operating spectrum. The synthesis of the obtained results is given, together with recommendations for optimal selection and optimal design of PFC main circuit elements with regard to achieving peak efficiency values.

An Overview of Saturable Inductors: Applications to Power Supplies

This article presents an overview of saturable inductors that are intentionally saturated by the load current and their applications to power supplies. After introducing the fundamentals of magnetization and nonlinear inductance, three types of saturable inductors are differentiated. They are based on the way nonlinearity of the core material is used. The partial saturation, the saturation of swinging inductors and the full saturation. Subsequently, this article focuses on the application to power supplies: it identifies the main reasons for using saturable inductors, like improving the efficiency or reducing the size of the magnetic component by using stepped air-gaps or partial saturation and gives an overview on this topic and its main publications. Afterwards some concepts and circuits taking advantage of saturable inductors are presented in more detail, especially improving the light load efficiency of a point of load buck converter, ensuring zero voltage switching over a wide load range in a phase-shifted full bridge circuit, a nonlinear commutation circuit, and a passive and active power factor correction.

Design and control of shunt active power filter for power quality improvement of utility powered brushless DC motor drives

ABSTRACT The presence of nonlinear loads like brushless DC (BLDC) motor drives in the distribution system leads to poor power quality (PQ) indices like low power factor, high total harmonic distortion and creates electromagnetic interference. Passive filters and Power factor correction converters are often inserted between the utility and BLDC motor drives to improve the PQ parameters. This paper proposes the shunt active power filter (SAF) for the PQ improvement of medium and high power BLDC motor drives. In this paper, the design steps and control of an SAF for a 20 kW BLDC motor drive are presented. The control of SAF is realized by applying the instantaneous “p–q” theory with the sinusoidal current control strategy. The current control is realized by a hysteresis controller. In contrast to normal electrical loads, the motor drive loads are subjected to continuous speed and load variations. This will result in fluctuations in the DC-link voltage of the SAF capacitor. Hence, the sliding mode controller is used for DC-link voltage control. The proposed methodology is validated in simulations and the experimental prototype. The enhancement of various PQ parameters is analysed for different loading conditions of the motor in the distorted and non-distorted distribution system voltage conditions.

The effect of greenhouse irradiators on the load factor of step-down transformers

The aim of the work is to determine the permissible load factors of step-down transformers when powering various types of greenhouse irradiators. All examined irradiators have nonlinear volt-ampere characteristic and generate upper current harmonics. The object of research are greenhouse illuminators with high pressure sodium lamps, induction and light-emitting diodes greenhouse illuminators (LED) with active and passive power factor. The permissible load factors of transformers are calculated using obtained data: for high-pressure sodium lamp light is 0.95 max; for LED lamps with active power factor corrector – 0.76 max; for LED lamps with passive power factor correction – 0.59 max; for electrodeless lamp light – 0.98 max. To reduce current harmonics in systems with LED lamps and to increase the load factor of transformers, it is necessary to apply special devices – active or passive harmonic filters. For greenhouse irradiators with sodium lamps and induction irradiators, the use of harmonic filters is not required.

Buck–Boost–Buck-Type Single-Switch Multistring Resonant LED Driver With High Power Factor and Passive Current Balancing

An integrated buck-boost-buck-type single-switch multistring resonant light-emitting diode (LED) driver is proposed and analyzed. It combines buck-boost and buck converters to achieve passive current balancing and power factor correction. With this circuit configuration, the proposed LED driver employs only one low-side connection active switch, resulting in a very simple control requirement involving one closed-loop controller for regulating one output current. Other output currents can be balanced automatically by resonant capacitor and storage capacitors, making the control strategy economical. In addition, high efficiency is achieved due to single-stage power conversion. Taking three-string LED driver as an example, the proposed buck-boost-buck-type single-switch LED driver is studied in terms of operating principle, current balancing principle, power factor (PF) analysis, voltage gain, and key circuit parameter design. Finally, an 84-W high-PF three-string LED driver prototype with 94.3% peak efficiency is built to verify the analytical results.

An Improved Power Factor Correction for Interleaved Flyback Switched Mode Power Supply

Nowadays the use of electronic equipment finds a progressive development in the modern world. Hence it becomes a mandate to check whether the harmonic content of line current of any electronic device which is connected to the ac supply meets the appropriate standards. This demand is satisfied by implementing the Power Factor Correction (PFC) circuit in order to make the input current to be in sinusoidal in nature and in-phase with the input voltage. Numerous solutions are available to make the line current almost sinusoidal. This paper deals with the inclusion of passive PFC in the interleaved Fly back SMPS to improve the power factor. The proposed work also examines the reduction of current ripple at the output using interleaved converter.

Нелинейные свойства полупроводниковых преобразователей напряжения для светодиодных источников света

Тhe main advantages of LED lamps over conventional light sources are considered. A converter of the input AC voltage into an output DC current with a power factor corrector (PFC) is one of a LED lamp’s main functional elements. The main advantages and disadvantages of active and passive PFCs as applied to their use in the composition of LED lamps are considered. The processes occurring in the converter with a passive PFC are represented by repeating groups of four time intervals with linking their boundaries to the instantaneous output voltage values. Equivalent circuit diagrams explaining the processes in different time intervals are given. The waveform of current consumed from the input voltage source with zero inner impedance is determined using the operator method for analysis of steady-state values and the classical method for analysis of transients. The current-voltage characteristics of the diodes are approximated by a piecewise linear function. The processes were mathematically simulated in the MathCAD computer-aided design system. For determining the harmonic composition of the consumed current, the function describing its waveform (which was calculated using the expressions presented in the article) is expanded into a Fourier series. For experimentally verifying the obtained results, a prototype converter with a passive PFC has been designed and fabricated. A comparison between the calculation results with experimental data is given. By using the presented analytical model of a voltage converter with a passive PFC it is possible to analyze the electromagnetic compatibility of LED lamp power supplies in terms of emitting higher harmonic components.

Analytical calculation method for the non-linear characteristic of ferrite-cored inductors with stepped air gap

Magnetic devices are essential components in the field of power electronics. Exploiting the non-linear behavior of inductors and transformers offers the great merit of increasing the performance of switch mode power supplies. For instance, the light-load efficiency of a buck voltage regulator can be improved by using a non-linear inductor with stepped air gap. Moreover, non-linear chokes can be used for passive power factor correction or are employed in solar PV systems. For an optimal design, however, a controlled decrease in inductance at a larger current is required. Such a characteristic is displayed by inductors with stepped air gaps. To optimize the gap geometry, the knowledge of the exact behavior of the non-linear choke is crucial. As simulation tools require rather long computation times to calculate the non-linear characteristic, the authors chose a different approach. This paper demonstrates the analytical calculation of the current depending inductance of pot cores with stepped air gap. By solving a boundary value problem the magnetic vector potential inside the winding area is obtained assuming linear core material. Subsequently, the non-linearity of the core material is incorporated by decomposing the original non-linear problem into linear subproblems. Following this, the solution of the original problem is composed using the solutions of the linear subproblems. Once the magnetic vector potential as a function of inductor current has been determined, the current depending inductance can be calculated. Results derived from both simulations with COMSOL Multiphysics and measurements show good agreement with the theoretical predictions.

Design and analysis of a single-phase low-frequency active power factor correction circuit: a symmetric trapezoidal current waveform approach

This paper focuses on the design and analysis of the single-phase Low-Frequency Active Power Factor Correction (LFAPFC) circuit. The LFAPFC circuit has several attractive features such as low electromagnetic interference, low switching frequency and ease of implementation when compared with the High-Frequency Active Power Factor Correction circuit. Moreover, its performance is much better than that of the Passive Power Factor Correction circuit. However, few of the previous studies focus on determining the values of major parameters of the LFAPFC circuit and their corresponding performance. To conduct an in-depth study on the LFAPFC circuit, this paper proposes a systematic design method based on analyzing the characteristics of a symmetric trapezoidal current waveform. Using the proposed method, output performance indices such as total harmonics distortion and power factor of the LFAPFC circuit can be estimated. In addition, the relationship among the output performance, inductance and conduction parameters of the power switch is derived and investigated. Using the proposed method, designers can determine suitable values of conduction parameters and inductance for specific applications. Computer simulations and real experiments are carried out to verify the effectiveness of the proposed method.

A New Single-Stage Small Power MH lamp Electronic Ballast

In this study, we proposed a new single-stage small power MH lamp electronic ballast and power-factor correction circuit with improved circuit by the current of passive power factor correction. Main circuit integrates traditional DC/DC and DC/AC circuits into one-stage DC/AC inverter. Moreover, we described the working principle and control strategy of the new circuit; it's soft switching principle; and resonant element parameter design formula. An experimental prototype of HID lamp electronic ballast with output power of 70 W was built to verify the feasibility of the analysis and design. The simulation and experimental results proved that the power factor of this circuit could reach 94%, with efficiency of 90%. The input current harmonics conform to IEC 61000-3-2 standards and its cost is low. These superior performances of the new circuit indicate certain practical values.

THE EFFECT OF ENERGY-EFFICIENT LIGHT SOURCES ON THE QUALITY OF ELECTRICITY

The paper analyzes the range of current from energy-efficient light sources (LSs), such as compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs). The studied LSs exceed the standard values for the current harmonics, even with passive power factor correction. We have developed a methodology for calculating relative errors of active energy meters that measure the energy used by CFLs and LEDs and applied the methodology to determine the values of the relative errors of the induction and the digital meters. It is found that the errors of of both types of electricity meters for measuring power in the circuits with the tested LSs–CFLs and LEDs–exceed the maximum permissible errors by 3.0 % and 4.0 % respectively. Thus, when the load is a source of non-sinusoidal current, a consumer is overcharged for electricity. The values of errors in electricity metering can be reduced by eliminating the causes of the deteriorating quality of electricity, i.e. by supplying the lighting installations with energy-efficient light sources provided with active power factor correction.

Measurement-Based Harmonic Modeling of an Electric Vehicle Charging Station Using a Three-Phase Uncontrolled Rectifier

The harmonic pollution of electric vehicle chargers is increasing rapidly as the scale of electric vehicle charging stations enlarges to meet the rising demand for electric vehicles. This paper investigates the operating characteristics of a three-phase uncontrolled rectification electric vehicle charger with passive power factor correction. A method for estimating the equivalent circuit parameters of chargers is proposed based on the measured feature data of voltage and current at the ac side and on the circuit constraint during the conduction charging process. A harmonic analytical model of the charging station is then established by dividing the same charger types into groups. The parameter estimation method and the harmonic model of the charging station are verified through simulation, experiment, and field test. The parameter sensitivities of the equivalent circuit to the charging current harmonic are also studied.

A Single-Switch Valley-Fill Power-Factor-Corrected Electronic Ballast for Compact Fluorescent Lightings With Improved Lamp Current Crest Factor

Although compact fluorescent lamps (CFLs) have been on the market for a long time, many of them do not achieve the same power factor as the incandescent lamps do, which presents a significant problem for the utility with the current widespread use of CFLs for household lightings. A simple single-switch electronic ballast with passive valley-fill power factor correction is proposed in this paper for CFL application. The proposed single-switch ballast circuit is able to achieve zero current switching to maximize the circuit efficiency. A simple feedback circuit with duty ratio control is also proposed to improve the high lamp current crest factor caused by the valley-fill circuit. Detailed descriptions and analysis of the circuit operating principles are provided in this paper. Simulation and experimental results are given on a 13-W CFL tube from Osram Sylvania to highlight the merits of the proposed work.

Capacity Calculation of Shunt Active Power Filters for Electric Vehicle Charging Stations Based on Harmonic Parameter Estimation and Analytical Modeling

The influence of electric vehicle charging stations on power grid harmonics is becoming increasingly significant as their presence continues to grow. This paper studies the operational principles of the charging current in the continuous and discontinuous modes for a three-phase uncontrolled rectification charger with a passive power factor correction link, which is affected by the charging power. A parameter estimation method is proposed for the equivalent circuit of the charger by using the measured characteristic AC (Alternating Current) voltage and current data combined with the charging circuit constraints in the conduction process, and this method is verified using an experimental platform. The sensitivity of the current harmonics to the changes in the parameters is analyzed. An analytical harmonic model of the charging station is created by separating the chargers into groups by type. Then, the harmonic current amplification caused by the shunt active power filter is researched, and the analytical formula for the overload factor is derived to further correct the capacity of the shunt active power filter. Finally, this method is validated through a field test of a charging station.

Forward Conduction Mode Controlled Piezoelectric Transformer-Based PFC LED Drive

Light-emitting diode (LED) illumination is getting more and more common; as LED’s performance is rising, the price is falling and is getting competitive. Some of the challenges of ac mains supplied illumination are the requirement of power factor correction (PFC) and the competitiveness of a low priced market. In this paper, a new forward conduction mode (FCM) control method for piezoelectric transformer (PT)-based power converters is proposed. A PT-based LED drive facilitating passive PFC is developed, utilizing and validating the FCM control method. The drive utilizes an inductorless half-bridge topology and for circuit minimization and simplicity it has no load regulation and has a 100-Hz output modulation. The proposed FCM control method ensures that the PT is operated at its optimal operation frequency, which ensures soft-switching operation and a constant gain. As a result a 6.5-W PT-based PFC LED drive has been developed, supplied from 230-V 50-Hz ac mains, achieving a power factor of 0.96.

고출력 MHL용 구형저주파 구동 방식의 전자식 안정기 설계

본 논문에서는 Buck Converter 동작 원리를 Full -Bridge Inverter에 적용한 전자식 안정기를 제안하였다. 전자식안정기는 EMI 필터, 수동 PFC, Full-Bridge Inverter로 2-stage로 구성되어 있다. PFC는 신뢰성 확보를 위해 수동 PFC를 사용하였다. Full-Bridge Inverter는 High Side와 Low Side 스위치의 구동 주파수를 각각 고주파와 저주파로 구동하여 Buck Converter의 동작을 구현 하였다. 램프를 저주파수 구형파로 구동하여 음향공명현상을 피하게 되었으며, 고주파수 스위칭으로 인덕터의 부피를 줄였다. 제안한 방법은 시뮬레이션과 실험을 통해 증명하였다. In this paper, We proposed electronic ballast that applys Buck Converter operation principle to Full-Bridge inverter. The proposed ballast consists of an EMI Filter, a full-bridge rectifier, a passive power factor correction (PFC) circuit and a full-bridge inverter. The passive PFC is used and a Full-Bridge inverter operation by two frequency. High Side and Low Side switch was driven by high frequency and low frequency and realized buck Converter's operation. The lamp is driven by Low Frequency square wave to avoid Acoustic Resonance. Also, bulk of inductor is reduced by high frequency switching. Performance of the proposed ballast was validated through computer simulation using Pspice, experimentation and by applying it to an electronic ballast for a prototype 700W MHL.

The Electronic Ballast Design of Acoustic Resonance Free and Transient Over Current Limit for High Power MHL

This paper presents the design of acoustic resonance free and over current limit during transient state consideration electronic ballast for 1.5kW Metal-Halide Lamp(MHL) that employs frequency modulation (FM) technique. The proposed ballast consists of a Full-Bridge(FB) rectifier, a passive power factor correction (PFC) circuit, a full-bridge inverter, an ignitor using LC resonance and a control circuit for frequency modulation. The frequency modulation technique is the most effective solution to eliminate acoustic resonance among other technique. It spreads power spectrum of lamp to reduce the supplied power spectrum under the energy level of eigen-value frequency. Moreover, the proposed ballast is simple and cost effective above conventional ballast. A new PFC circuit is proposed which combines with LCD type and PCSR filter. A new PFC circuit has higher PF and lower THD than conventional LCD type and secure high reliability. Finally, to protected switching components in transient state, the surge current into ballast is limited by increase the switching frequency. Performance of the proposed ballast was validated through computer simulation using Pspice, experimentation and by applying it to an electronic ballast for a prototype 1.5kW MHL.

A Unity Power Factor Correction Preregulator With Fast Dynamic Response Based on a Low-Cost Microcontroller

Low cost passive power factor correction (PFC) and single-stage PFC converters cannot draw a sinusoidal input current and are only suitable solutions to supply low power levels. PFC preregulators based on the use of a multiplier solve such drawbacks, but a second stage dc-dc converter is needed to obtain fast output voltage dynamics. The output voltage response of PFC preregulators can be improved by increasing the corner frequency of the output voltage feedback loop. The main drawback to obtaining a faster converter output response is the distortion of the input current. This paper describes a simple control strategy to obtain a sinusoidal input current. Based on the static analysis of output voltage ripple, a modified sinusoidal reference is created using a low cost microcontroller in order to obtain an input sinusoidal current. This reference replaces the traditional rectified sinusoidal input voltage reference in PFC preregulators with multiplier control. Using this circuitry, PFC preregulator topologies with galvanic isolation are suitable solutions to design a power supply with fast output voltage response (10 or 8.33 ms) and low line current distortion. Finally, theoretical and simulated results are validated using a 500 W prototype.