Single-stage Converter Research Articles

Class-D Zero-Current-Switching Rectifier as Power-Factor Corrector for Lighting Applications

An analysis and design of a zero-current-switching (ZCS) Class-D current-source driven rectifier for the lighting applications is presented, which is one of the resonant rectifiers as a power-factor corrector to improve a poor power-factor and high line current harmonic of a single-stage converter. A high power-factor is achieved by the utilization of output characteristics of a Class-D ZCS rectifier, which is inserted between the front-end bridge rectifier and the bulk-filter capacitor. The conduction angle of the bridge rectifier diode current was increased and a low-line current harmonic and a power-factor near unity can be obtained. The design procedure is based on the principle of the Class-D ZCS rectifier, which also ensures more accurate results and the proposed scheme provides a high efficiency and a more systematic and feasible analysis methodology. The active switches can be operated under the soft-switching condition. The validity of this approach was confirmed by simulation and experimental results.

Improvement of closed-cycle sulfur recovery from coke-oven gas

Improvement in the closed-cycle technology for sulfur removal from coke-oven gas used in the by-product shop of the coke plant at OAO Magnitogorskii Metallurgicheskii Kombinat is considered, with a view to more effective sulfur extraction and lower capital costs. The efficiency of hydrogen-sulfide conversion in the system for sulfur recovery at OAO MMK is such that additional catalytic conversion is unnecessary. To identify the most active catalyst for single-stage conversion of sulfur-bearing gases, monitoring data for the industrial reactor in the sulfur-production department in the Polar Division Copper Plant of MMC Norilsk Nickel are analyzed. Of the four catalysts tested, the most effective is AOK-78-59 aluminum-oxide catalyst, produced by OOO Katalizator (Novosibirsk).

Comparison of Z Source and Embedded Z Source Inverters in Micro Wind Power Generation System

To meet the huge demand of power, the micro wind power generation system plays a major role in generating it at lesser cost. A comparison study between the single phase Z source and embedded Z source inverters in a micro wind power generation system are carried out. The unique feature of both the inverters is shoot through duty cycle by controlling which any desired output voltage even greater than input line voltage is possible. Both Buck-Boost capabilities in single stage conversion are possible. This is not possible in conventional inverters. The results of Z source and EZ source inverter systems are presented.

Improved Output Voltage in Micro Wind Power Generator Fed Z Source Inverter Based System

The micro wind power generation system is used to generate the power at low cost. In this paper, generator fed SEPIC, Z source inverter based systems are presented. The unique feature of Z source inverter is shoot-through duty cycle control by which any desired output voltage even greater than input line voltage is possible. Both buck-boost capabilities in single stage conversion are possible. This is not possible in conventional inverters. Also conversion losses are reduced in Z-source inverter due to single stage conversion which increases the output voltage of the system. Keywords: micro-wind power generation system, Single-Ended Primary Inductor converter, Z source inverter.

The Ripple Cancellation Technique Applied to a Synchronous Buck Converter to Achieve a Very High Bandwidth and Very High Efficiency Envelope Amplifier

This paper presents a single-stage converter for a high-bandwidth and high-efficiency envelope amplifier. In the proposed application, due to the high peak-to-average-power ratio, high bandwidth, and the power level requirements, the envelope amplifier has low efficiency. Therefore, many efforts have been made to increase the efficiency of the envelope amplifier. To achieve this improvement, the current ripple cancellation technique is applied in this paper to a synchronous buck converter to cancel the output current ripple and to decrease the switching frequency without a reduction in the large signal bandwidth, for open-loop operation and for the envelope elimination and restoration technique. The advantages of the proposed design are presented and validated experimentally. The transfer function of the output filter of the buck converter with a ripple cancellation circuit has been modeled and compared to measurements, showing a good correspondence. Experimental validation is provided at 4 MHz of switching frequency, for dc and for variable output voltage, applying a sinusoidal reference and a 64-QAM signal. Experimental validation of the efficiency improvement is provided, compared to the equivalent design of the conventional buck converter in terms of the output voltage ripple rejection ratio and large signal bandwidth.

Solving Technical Problems on the Full-Bridge Single-Stage PFCs

AC-DC conversion with power factor correction using full-bridge single-stage (FBSS) converters may introduce various complex operating limits and control problems that are not usually described in literature. This is mainly due to the fact that they devaluate and restrict the number of applications of those topologies. These problems are identified as primary transformer saturation and output voltage perturbations. The operation at light loads and with wide load variation is also a complex issue that leads to uncontrollable input current and dc bus voltage. This paper clarifies such technical problems referring their impact in the FBSS topologies operation, and presents design criteria and control solutions to minimize their effects. A low cost free wheeling circuit (FWC) that allows null input current to solve the light load operation problem is also presented.

Mo1802 Single Stage Conversion From Gastric Banding to a Stapled Bariatric Procedure: An Analysis of Complications

Mo1802 Single Stage Conversion From Gastric Banding to a Stapled Bariatric Procedure: An Analysis of Complications

A Comparative Study of Two Buck-Type Three-Phase Single-Stage AC–DC Full-Bridge Converters

Almost all previously proposed single-stage, three-phase ac-dc converters are based on the boost converter, and the strengths and weaknesses of boost-based single-stage converters are well known. This is not the case for buck-based single-stage converters as little, if any, comparable research has been performed on these converters. The authors have previously investigated a three-phase ac-dc, single-stage buck-type converter that can simultaneously perform power factor correction and dc-dc conversion using the standard phase-shift pulse-width modulation technique for dc-dc full-bridge converters. This paper is a continuation of that work as its main focus is a comparison of the performance and characteristics of this converter with those of a modified version of the same converter. In this paper, the fundamental principles of both the converters are explained, the modes of operation of the modified converter are explained in detail and a procedure for the design of this converter is demonstrated with an example. Experimental results obtained from a prototype of the modified converter are presented and based on these results; the two converters are compared in terms of parameters such as input power factor and efficiency.

A Three-Level Integrated AC–DC Converter

In this paper, a new integrated three-level ac-dc converter is presented. The proposed converter integrates the operation of the boost power factor correction and the three-level dc-dc converter. The converter is made to operate with two independent controllers-an input controller that performs power factor correction and regulates the dc bus and an output controller that regulates the output voltage. The input controller prevents the dc-bus voltage from becoming excessive while still allowing a single-stage converter topology to be used. The paper explains the operation of the new converter in detail and discusses its features and a procedure for its proper design. Experimental results obtained from a prototype are presented to confirm the feasibility of the new converter.

Performance Analysis of Different Control Methods of Z-source Inverter Feeding Induction Furnace Load

Ever increasing demand for electric energy along with the growing environmental concerns and limited fossil fuel resources, the renewable energy sources are gaining increasing impetus across the globe. The output voltage of these renewable energy sources has a variation range. In these situations an additional DC-DC boost converter or step-up transformer is usually needed. The Z-source inverter (ZSI) is an emerging topology for power electronics converters with very interesting properties such as buck boost characteristics and single stage conversion. In this work, the performance of four control techniques of Z-source inverter - simple boost control, maximum boost control, maximum constant boost control & third harmonic injected maximum constant boost control with induction furnace load, are compared. The simulation results based on MATLAB/Simulink are presented to illustrate the performance comparison of control techniques of ZSI for reducing the harmonic distortion in the load current with induction furnace load in the distribution network.

High-Voltage Gain Boost Converter Based on Three-State Commutation Cell for Battery Charging Using PV Panels in a Single Conversion Stage

This paper presents a novel high-voltage gain boost converter topology based on the three-state commutation cell for battery charging using PV panels and a reduced number of conversion stages. The presented converter operates in zero-voltage switching (ZVS) mode for all switches. By using the new concept of single-stage approaches, the converter can generate a dc bus with a battery bank or a photovoltaic panel array, allowing the simultaneous charge of the batteries according to the radiation level. The operation principle, design specifications, and experimental results from a 500-W prototype are presented in order to validate the proposed structure.

Add-Equalize Structures for Linear-Phase Nyquist FIR Filter Interpolators and Decimators

This paper introduces add-equalize structures for the implementation of linear-phase Nyquist ( $M$ th-band) finite-length impulse response (FIR) filter interpolators and decimators. The paper also introduces a systematic design technique for these structures based on iteratively reweighted $\ell _{1}$ -norm minimization. In the proposed structures, the polyphase components share common parts which leads to a considerably lower implementation complexity as compared to conventional single-stage converter structures. The complexity is comparable to that of multi-stage Nyquist structures. A main advantage of the proposed structures is that they work equally well for all integer conversion factors, thus including prime numbers which cannot be handled by the regular multi-stage Nyquist converters. Moreover, the paper shows how to utilize the frequency-response masking approach to further reduce the complexity for sharp-transition specifications. It also shows how the proposed structures can be used to reduce the complexity for reconfigurable sampling rate converters. Several design examples are included to demonstrate the effectiveness of the proposed structures.

A Novel High-Efficiency High-Power-Factor Single-Stage Converter for Small-Scale Wind Power Generation System

In this paper, a novel single-stage ac/dc converter for small-scale wind power generation system is proposed. The power factor correction of line currents for wind power is achieved so as to reduce the harmonic currents and decrease the wind turbine noise. The proposed converter has both zero-voltage switch in the primary-side switches and zero-current transition in the secondary-side diodes. Compared with a traditional two-stage converter, high efficiency and high set-up voltage ratio are also accomplished in the proposed single-stage three-phase converter. In addition, based on the proposed wind converter, only the MPPT control algorithm needs to be considered to achieve both power factor correction and MPPT functions. Finally, a prototype system is constructed by utilizing the controller DSP 28335. The simulation and experimental results verified the validity of the proposed converter.

A Novel Approach for an Enhanced High Frequency Single Stage Matrix Converter for Induction Heating Application

Conventional Converters usually implement AC-DC-AC Structures for high frequency Induction Heating. This results in large harmonic currents and power factor near to unity. This paper highlights AC-AC single stage converter topology for Induction heating. The Matrix Converter provided in this topology helps gain high frequency besides high input power quality. Since the input phases are directly linked to output phase, intermediate storage device is eliminated. The Present system in its soft commutation mode is the configuration of an Induction heater Modeling and Simulation of the proposed system which is exemplified.

전해 커패시터를 제거하고 디밍이 가능한 고수명 단일단 PFC DCM 플라이백 컨버터

Light emitting diode(LED) lighting has been applied various industry fields because of its high efficiency, low power consumption, long life time, and environment friendly characteristics. Generally, LED lighting needs a driver to maintain constant current. Most popular driver is the switching converter. In the converter, there are several electrolytic capacitors. However the lifespan of the electrolytic capacitor is much shorter than LED. Therefore the lifespan of LED lighting with electrolytic capacitor is decreased. Also, LED lighting needs dimming control because of various needs and energy saving. This paper presents the dimmable single-stage PFC DCM flyback converter without electrolytic capacitor and parallel LC resonant filter for reducing 120[Hz] ripple on the output. The type 2 controller is used to maintain constant current and the analog dimming control is used. The proposed converter is verified through simulation and experimental works.

A Three-Phase Single-Stage AC–DC PWM Buck-Type Full-Bridge Converter: Analysis, Design, and Characteristics

The main objective of this paper is to examine the operation of a fundamental buck-based three-phase single-stage ac-dc full-bridge converter. In this paper, the operation of this fundamental converter is explained and analyzed, and a procedure for the design of its key components is derived and demonstrated with an example. The performance and characteristics of the converter are shown with experimental results that have been obtained from a prototype, and general concluding remarks comparing buck-based and boost-based three-phase single-stage ac-dc full-bridge converters are made.

A New Single-Phase Single-Stage Three-Level Power-Factor-Correction AC–DC Converter With Phase-Shift Modulation

A new three-level ac-dc single-stage converter that can operate with standard phase-shift pulsewidth modulation is proposed in this letter. In this letter, the operation of the converter is explained, and its feasibility is confirmed with experimental results obtained from a prototype converter. Finally, the efficiency of the new converter is compared with that of a previously proposed converter of the same type, and it is shown that the new converter has better efficiency, particularly for light-load operation.

Effect of metal content on the behavior of Pt/SAPO-31 catalysts in the hydroconversion of sunflower oil

It is shown that catalysts based on Pt/SAPO-31 can be used for the single-stage conversion (in contrast to the two-stage commercial process) of vegetable oil into waxy diesel fuel components. The effect of the content of metal (0.5–2 wt % Pt) in the catalyst on its physicochemical and catalytic properties is studied. It is found that regardless of the platinum content, the activity of the catalysts diminishes during the reaction, as is indicated by a drop in their isomerization ability and the presence of oxygen-containing compounds in the reaction products. The physicochemical properties of Pt/SAPO-31 catalysts are studied via the IR spectroscopy of adsorbed pyridine, hydrogen chemisorption, and transmission electron microscopy. It is shown that the catalytic degradation is caused by the poisoning of the acid sites and a reduction in the active surface area of the metallic component. Possible ways of improving the on-stream stability of Pt/SAPO-31 samples in the hydroconversion of vegetable oil are described.

Single-Phase Single-Stage Transformer less Grid-Connected PV System

In this paper, a single-phase, single-stage current source inverter-based photovoltaic system for grid connection is proposed. The system utilizes transformer-less single-stage conversion for tracking the maximum power point and interfacing the photovoltaic arrays to the grid. The maximum power point is maintained with a fuzzy logic controller. A proportional-resonant controller is used to control the current injected into the grid. To improve the power quality and system efficiency, a double-tuned parallel resonant circuit is proposed to attenuate the second- and fourth- order harmonics at the inverter dc side. A modified carrier-based modulation technique for the current source inverter is proposed to magnetize the dc-link inductor by shorting one of the bridge converter legs after every active switching cycle. Simulation and practical results validate and confirm the dynamic performance and power quality of the proposed system.

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.