Single-stage Topology Research Articles

Improved Single-Phase Split-Source Inverter With Hybrid Quasi-Sinusoidal and Constant PWM

A single-stage topology of a three-phase boost inverter known as split-source inverter (SSI) has recently been introduced in the literature. This topology suffers from high frequency current commutations across two diodes and complicated analysis since the inductor is charged with variable duty cycle. This paper presents a single-phase version of SSI with improvements in inverter topology as well as the pulse width modulation (PWM) technique. An inductor is connected to two MOSFETs operating at fundamental frequency to boost the voltage from input source to dc-link voltage. In the proposed hybrid quasi-sinusoidal and constant PWM, one of the full-bridge legs undergoes constant duty cycle switching while the other one undergoes sinusoidally varying duty cycle switching, with the former is accountable for charging and discharging of inductor while the latter is accountable for producing ac output. Therefore, the proposed topology with hybrid quasi-sinusoidal and constant PWM exhibits the merit of simplicity since the control of dc-link voltage and ac output is detached within the single-stage topology. It is not liable to the undesired high frequency current commutation. In addition, a wide range of ac output voltage is achievable in either buck or boost operation. Theoretical analysis is presented and verified through simulation and experimental results.

Single‐stage QR AC–DC converter based on buck–boost and flyback circuits

In this study, a single-stage quasi-resonant (QR) AC–DC converter based on buck–boost and flyback circuits is proposed. The forestage buck–boost circuit works in discontinuous conduction mode to achieve a high-input power factor (PF), and the backstage flyback converter, working in QR mode, is responsible for energy transfer. The QR switch mode can improve the efficiency of the converter by decreasing the switch turn-on losses. The single-stage topology can reduce the cost and raise the reliability of the system. The detailed design process is described in this study, and a 50 W prototype was developed that has a maximum PF higher than 0.99 and a maximum efficiency of 90.91% in nominal working conditions.

Three‐phase grid‐tied single‐stage solar energy conversion system using LLMS control algorithm

In this study, a three-phase grid-tied single-stage solar energy conversion system (SECS) is implemented using a leaky least mean square (LLMS) based control algorithm. The SECS extracts the solar energy from the photovoltaic cells and converts it into electrical energy. The SECS makes use of voltage source inverter to invert the extracted DC power into the three-phase AC power. Apart from SECS, this system configures a three-phase grid, ripple filters and connected linear or non-linear loads. The main objective of this system is to eliminate power quality issues such as harmonics, voltage fluctuations and flickers, unbalancing in loads, reactive power requirement and so on. Moreover, this system operates at unity power factor and zero voltage regulation modes. In this study, SECS employs a single-stage topology controlled by perturb & observe approach of maximum power point tracking technique and for extracting fundamental component of load currents, a LLMS-based adaptive neural network control method is used. This system is modelled, designed and simulated in MATLAB using simpower system toolbox and experimental validation is carried out on a developed prototype in the laboratory.

Variable-Mirror Amplifier: A New Family of Process-Independent Class-AB Single-Stage OTAs for Low-Power SC Circuits

This paper presents a new family of Class-AB operational transconductance amplifier (OTA) circuits based on single-stage topologies with non-linear current amplifiers. The proposed variable-mirror amplifier (VMA) architecture is mainly characterized by generating all Class-AB current in the output transistors only, by exhibiting very low sensitivity to both technology and temperature deviations, and by avoiding the need for any internal frequency-compensation mechanism. Hence, this family of OTAs is well-suited for low-power switched-capacitor circuits and specifically optimized for switched-OpAmp fast on-off operation and multi-decade load-capacitance specifications. Analytical expressions valid in all regions of operation are presented to minimize VMA settling time in discrete-time circuits. Also, a complete OTA design example integrated in 0.18 $\mu\text{m}$ 1P6M MiM 1.8 V CMOS technology is supplied with detailed simulation and experimental results. Compared to resistor-free state-of-art Class-AB OpAmp and OTA literature, the proposed architecture returns the highest measured figure-of-merit value.

Maximum power point tracking algorithms for single-stage photovoltaic power plants under time-varying reactive power injection

The power electronic interface of traditional grid-connected photovoltaic (PV) systems includes a boost dc/dc converter and an inverter. In large PV power plants, the boost converter is usually eliminated by connecting an appropriate number of PV panels in series to achieve the desired voltage. This architecture, referred to as single-stage topology, is the subject of this paper. The paper presents a unified dynamic model which is able to reproduce the behavior of any single-stage PV power plant with an arbitrary PV array configuration through a single circuital representation. A methodology based on this unified model is developed to enhance the performance of standard iterative maximum power point tracking (MPPT) algorithms under time-varying reactive power injection. In particular, enhanced versions of the perturb & observe and incremental conductance algorithms are discussed. Furthermore, a predictive MPPT algorithm based on a neural network is proposed to improve the dynamic of the dc-link voltage. The unified model and MPPT control schemes are validated via detailed PSCAD/EMTDC computer simulations in a 450kW PV system, designed according to a typical “1000V dc” architecture. Real solar irradiance and cell temperature data collected in a partially cloudy day are utilized in the simulations, providing comparative performance under rapidly changing atmospheric conditions.

A Comparative Performance Investigation of Single-Stage Dimmable Electronic Ballasts for Electrodeless Fluorescent Lamp Applications

This paper presents a comparative investigation, design and development issues about six different single-stage topologies, applied as electronic ballasts, for electrodeless fluorescent lamps. The ballast is intended to feed a 100 W lamp at 250 kHz, with dimming feature. The proposed topologies use different converters for the power factor correction (PFC) stage: Buck-Boost, SEPIC, Zeta, Cúk, Flyback, and Boost. All of them operate in discontinuous conduction mode. A resonant half-bridge inverter is used as lamp power control (PC) stage. The integration of both stages (PFC and PC) is proposed in this paper. In this way, it is possible to reduce the number of active switches, as well as simplify the required driving and control circuitry. Experimental results demonstrate the feasibility of the proposed dimming technique that achieved around 56% lamp power dimming, from 100 W down to 44 W. The implemented topologies attained high average power factor (>0.98), and low line current average total harmonic distortion (<;15.3%). A comparison among all the proposed topologies in terms of power factor, harmonic distortion, efficiency and number of components is presented. Finally, a comparison between an integrated and a nonintegrated SEPIC half-bridge converter is also performed.

An Efficient Design for Interleaved Active Clamp Flyback Used in Grid-Connected Solar Microinverter

This document presents a high efficient method for interleaved active clamp flyback used in microinverter. The flyback converter was selected as a single stage topology that can boost the low PV panel voltages to a rectified AC output. How to handle the leakage energy for high efficiency and protecting the MOSFET ,how to calculate the parameter and choose the compenent also be showed in this document.

Z-Source\/Quasi-Z-Source Inverters: Derived Networks, Modulations, Controls, and Emerging Applications to Photovoltaic Conversion

The current and emerging investigations on Z-source/quasi-Z-source inverters (ZSIs/qZSIs) are presented. The ZSI/qZSI fulfills buck/boost capability in single-stage topology and overcomes the limits of traditional voltage source inverters (VSIs). Hence, high reliablity, high efficiency, and low cost can be achieved. The recently derived impedance networks with improved voltage gain are discussed. The classic and newly proposed modulations and feedback controls for ZSIs/qZSIs are compared. Finally, the emerging applications and trends of ZSIs/qZSIs to photovoltaic (PV) power generation are discussed. This study offers a comprehensive and systematic reference for the future development of the high-performance ZSI/qZSI.

Single-Stage Multistring PV Inverter With an Isolated High-Frequency Link and Soft-Switching Operation

A grid-tied multistring photovoltaic (PV) inverter with a high-frequency ac (HFAC) link, soft-switching operation, and high-frequency (HF) galvanic isolation is introduced. This single-stage topology can handle an arbitrary number of PV strings with different electrical parameters, locations, and orientations. Using a dedicated maximum power point tracker for each PV string, this inverter can harvest the highest possible power from each string independently, even though they might be at dissimilar irradiance levels and operating temperatures. The isolated HFAC link is formed by the magnetizing inductance of a small-sized HF transformer and two small ac capacitors without the use of bulky short-life electrolytic capacitors. The link is responsible for transferring the PV strings' power to the grid along with creating zero-voltage switching for the power devices. Therefore, the converter has the advantages of high power density, high reliability, as well as high efficiency. After describing the control scheme and the operating algorithm of the proposed multistring inverter, a detailed analysis is carried out. The experimental results of the developed 1-kW two-string prototype with different PV strings at various PV conditions are also shown. The results verify the effectiveness of the topology in tracking the maximum power of each string independently without affecting the operating condition and control of the other string.

Optimization and Performance Evaluation of an AC-Chopper Ballast for HPS Lamps

Electronic ballasts for high-pressure sodium lamps based on an ac-chopper topology are proposed as a cheaper and less complex alternative to the industry-standard low-frequency square-wave ballasts. In this paper, the design process of the ac-chopper ballast is reviewed, and the design tradeoffs caused by the single-stage topology are discussed. The analytical and simulation results are verified with measurements of a 250-W prototype system, including a detailed list of the losses for the different circuit components and electromagnetic compatibility measurements. Due to the disadvantages of the single-stage topology, a comparison to a two-stage ballast using the inverter stage of the ac-chopper ballast with a separate power factor correction stage is provided.

The Modified Control Method for the Single-Stage Three-Phase GridConnected Photovoltaic System

Single-stage topology and the maximum power point tracking (MPPT) algorithm have advantages such as simple configuration and high efficiency in grid-connected photovoltaic (PV) systems. In conventional systems, current and voltage sensors of PV system are normally used for MPPT. This paper presents a modified control algorithm for the single-stage three-phase grid-connected PV system without PV current sensor with a variable step MPP-tracker. This algorithm is not derived from complex state equations and is not dependent on any circuit parameters. It simply calculates the output power of the inverter to replace the input power of the PV systems in the MPPT algorithm. The modified algorithm is simulated by using Matlab/Simulink software and implemented in the experimental prototype. With the single-stage configuration and PV current sensorless method, the prototype is suitable for lowcost high efficient implementation in the practice.

Single Stage Single Switch Power Supply (S4PS)Design for Low Power HB-LED Lighting

Abstract This paper presents an improved power quality converter (IPQC)-based power supply design for high brightness light emitting diode (HB-LED) low power lighting. The IPQC circuit uses a Cuk buck-boost converter to operate it in a discontinuous conduction mode (DCM) using the voltage follower technique for the mitigation of harmonic contents present in the AC mains current. Subsequently, reduction in harmonic contents results in improving the power quality indices at the AC mains. Single-stage single switch converter topology is used, which has less component count, size and cost as compared to the two-stage converter topology. DCM operation has an advantage that only output voltage control loop is required as compared to three control loops required in the continuous conduction mode operation. An 18-W LED driver is designed, modeled and simulated using MATLAB/Simulink software for 220 V, 50 Hz AC mains. The performance of the proposed LED driver is observed in terms of total harmonic distortion of the input current (THDi), input power factor (PF) and crest factor (CF) taking into account the strict international standard of IEC 61000-3-2 for class C equipments.

Research on the MPPT Stability of the Single-Stage and Single-Phase Photovoltaic Grid-Connected System

At present the multi-stage transformation topology are more used in photovoltaic (PV) grid-connected system, although the control of this structure is relatively simple but the conversion efficiency is difficult to improve due to increase in transformation series. The single stage topology has a simple topology with high reliability and efficiency because of low power consumption, but control algorithm is more complex because of its power convert main circuit without DC-DC. This paper describes a method for maximum power point tracking (MPPT) in the single-stage and single-phase PV grid-connected system. In the paper, the nonlinear output characteristics of the PV including I-V &amp; P-V are obtained in changed solar insulations or temperature based on MATLAB, and the MPPT algorithm which is based on the particle swarm optimization (PSO) method is also described. The simulation model of the single-stage and single-phase PV grid-connected system is built , and simulation results show the MPPT algorithm has excellent dynamic and static performances ,which verifies the PSO method is effective for MPPT in the single-stage and single-phase PV grid-connected system.

Single-stage driver for supplying high-power light-emitting-diodes with universal utility-line input voltages

The conventional two-stage non-isolated driver for high-power light-emitting diodes (LEDs) is composed of a power-factor-correction (PFC) converter with a non-isolated flyback converter for regulating the output voltage/current for supplying LEDs. However, large numbers of circuit components are required and the total efficiency is limited because of two-stage power conversion. This study proposes a high-power LEDs driver based on a single-stage topology. The presented driver combines a buck-boost PFC converter with a non-isolated flyback converter with two output windings connected in series into a single-stage power-conversion circuit. The proposed driver offers high power factor, high efficiency, low total-harmonics-distortion (THD) of input utility-line current, cost-effectiveness and a constant-output voltage along with limited-output-current control scheme. Finally, a prototype driver is developed and tested in order to supply a 100 W LED light bar module with universal utility-line input voltages for indoor or outdoor general lighting applications. Operational analysis, design equations, a design example and experimental results provided by examining three LED light bar modules demonstrate the feasibility of the proposed circuit.

Single-stage single-switch PFC converter for wide-input extreme step-down voltage applications

SUMMARY This paper presents a new single-stage single-switch high power factor correction AC/DC converter suitable for low-power applications (< 150 W) with a universal input voltage range (90–265 Vrms). The proposed topology integrates a buck–boost input current shaper followed by a buck and a buck–boost converter, respectively. As a result, the proposed converter can operate with larger duty cycles compared with the existing single-stage single-switch topologies, hence, making them suitable for extreme step-down voltage conversion applications. Several desirable features are gained when the three integrated converter cells operate in discontinuous conduction mode. These features include low semiconductor voltage stress, zero-current switch at turn-on, and simple control with a fast well-regulated output voltage. A detailed circuit analysis is performed to derive the design equations. The theoretical analysis and effectiveness of the proposed approach are confirmed by experimental results obtained from a 100-W/24-Vdc laboratory prototype. Copyright © 2011 John Wiley & Sons, Ltd.

New Optimized Full-Bridge Single-Stage AC/DC Converters

The inclusion of a few additional diodes and passive elements in the high-frequency full-bridge ac-dc converter with galvanic isolation permits one to achieve sinusoidal input-current wave shaping and output-voltage regulation simultaneously without adding any auxiliary transistors. Recently, this procedure, together with an appropriate control process, has been used to obtain low-cost high-efficiency single-stage converters. In an attempt to improve the performance of such converters, this paper introduces three new single-stage full-bridge ac-dc topologies with some optimized characteristics and compares them with the ones of the existing full-bridge single-stage topologies. The approach used consists in the definition of the operating principles identifying the boost function for each topology, their operating limits, and the dependence between the two involved conversion processes. Experimental results for each topology were obtained in a 500-W modular laboratory prototype that was built with the necessary flexibility to allow the realization of each different topology. Comparison was evaluated in terms of input-current distortion, efficiency, and output-voltage disturbances that result from the input-current wave-shaping process.

Techniques to obtain single-stage power supplies with power factor correction (PFC)

In order to comply with the standards, the input current of the switch mode power supplies (SMPS) must be almost sinusoidal, i.e. the SMPS must achieve power factor correction. This requirement is normally reached with the use of an additional input converter, typically a boost, resulting in a two-stage SMPS with the inherent drawbacks: high cost and the necessity of high efficiency in each stageto obtain a reasonable global efficiency. This article introduces two simple techniques together with the control strategies that can be used to obtain single-stage SMPS, that allow the control of the output voltage and the sinusoidal input current wave shaping, without any additional stage. Another objective of this article is to investigate and to evaluate the performance of each topology that emerged from the chosen technique. Considering high-power applications, experimental results of two single-stage full-bridge topologies are also presented, in order to verify the concepts introduced in the article.

Single-stage topologies integrating battery charging, high voltage step-up and photovoltaic energy extraction capabilities

The concept is presented of converters integrated in such a way as to obtain, in a single conversion stage, the maximum energy extraction from photovoltaic panels, battery charging and discharging dynamic control, and high voltage step-up to the inverter DC bus, also operating with soft-switching capability. Although this idea can be applied to most of the high voltage gain topologies, this presented report is based on structures derived from the half-bridge boost converter. Thus, a 500 W prototype, with input voltage of 24 V and output voltage of 200 V, has been developed with the purpose of obtaining experimental results and validating the proposed concept. High efficiency is achieved, above 92.5, confirming the expected operation and functionalities necessary for the proposed application.

A Novel High-Power-Factor Single-Switch Electronic Ballast

A novel single-stage single-switch electronic ballast topology with a unity power factor is presented in this paper. The proposed circuit consists of an integrated buck-boost stage that operates in the discontinuous conduction mode to provide a high power factor and a single-switch current-fed resonant inverter to stabilize the lamp current. The proposed topology presents a low cost and compact electronic ballast design method. The detailed descriptions of the circuit's operating principles are provided in this paper. The design equations and mathematical analysis regarding the proposed circuit are discussed in this paper. The proposed ballast has been tested with an 18-W compact fluorescent lamp, and the experimental results confirmed that a very high power factor of 0.995 and an efficiency of 83.4% have been achieved.

A SINGLE-STAGE PHASE-SHIFTED FULL-BRIDGE ELECTRONIC BALLAST FOR HIGH-PRESSURE MERCURY LAMPS

This paper presents a single-stage high-frequency full-bridge electronic ballast for high-pressure mercury lamps in high-luminance LCD projector systems. The studied electronic ballast is found to have high conversion efficiency due to its single-stage circuit with zero-voltage switching features. A high power factor can be achieved by using developed single-stage topology. The operation principles and design considerations are analyzed and discussed in detail. A laboratory prototype is designed and implemented for driving a 150 W projector lamp. The simulation and experimental waveforms are given to verify the feasibility of the proposed method.