Single-stage Buck-boost Inverter Research Articles

A Common Grounded Zeta-Canonical Switching Cell Single-Stage Buck–Boost Inverter

A Common Grounded Zeta-Canonical Switching Cell Single-Stage Buck–Boost Inverter

Novel Family of Flying Inductor-Based Single-Stage Buck–Boost Inverters

Single-phase buck–boost inverters are very popular nowadays due to the wide input voltage range regulation capability. This feature is mostly demanded by photovoltaic (PV), fuel cell, or battery storage applications. In this study, four new structures from the family of flying inductor (FI)-based inverters are presented. Performance in a wide range of input dc voltages and the ability to increase the voltage in single-power processing stage is one of the features of the proposed structures. Three of the four structures are common ground and completely bypass the parasitic capacitors which make them attractive for PV application. Nonuse of electrolytic capacitors in the proposed structures helps to increase the life of the converter and also there is no unpleasant inrush current of charging electrolytic capacitors in these structures. The operation modes are fully explained, as well as the theoretical analysis and design of passive elements have been done. Finally, the simulation and 2 kW laboratory circuit for the proposed Type-III structure are performed and the results are investigated.

Single-Stage Buck–Boost Inverters: A State-of-the-Art Survey

Single-stage buck–boost inverters have attracted the attention of many researchers, due to their ability to increase/decrease the output voltage in one power conversion stage. One of the most important uses of these inverters is in photovoltaic applications, where the voltage of the solar panels varies in a wide range. In recent years, many new inverters have been proposed to improve the performance of existing structures. In this paper, the state of the art of these single-stage buck–boost inverters is discussed. The advantages and disadvantages of each structure are examined from different perspectives, such as the number of components, losses, and performance. Finally, in a general comparison, the properties of all structures are discussed and summarized in a table.

Single-Phase Photovoltaic Inverters With Common-Ground and Wide Buck–Boost Voltage Operation

The output voltage of a photovoltaic panel is greatly affected by irradiance, temperature, shading, etc. A buck-boost type inverter is, therefore, required to accommodate the wide fluctuations in dc voltage. This article proposes a class of single-phase, single-stage buck-boost inverters employing five switches (implemented using power MOSFETs with external fast recovery diodes) to provide buck-boost operation for wide variations in photovoltaic (PV) output voltage. In this article, the proposed inverters are immune from current shoot-through problems associated with voltage source inverters, easing the requirement for PWM dead-times. They also provide a common-grounding feature between the grid-neutral and the negative-terminal of the PV panel, successfully suppressing the PV leakage current. In addition, they provide reactive power support. A simple input boost inductor-based buck-boost inverter is proposed with a wide gain range; other variants are also proposed based on the switched inductor, quadratic boost, and switched coupled-inductor, achieving higher boost voltage inversions with smaller values of duty ratio. Detailed circuit operations are presented based on proposed modulation strategies. Design guidelines/requirements of components and their comparisons are provided for all of the proposed inverters. The theoretical analysis and performance characteristics of all four topologies are experimentally validated using 400 VA laboratory prototype inverters.

Buck and Boost Inverter

Abstract: A versatile operation of any electronic circuitry depends on the power source supplying the power for its operation. The buck converter is implemented using an integrated circuit(IC), LM317. The constructed buck converter was tested for load and line regulation cited in the datasheets for stability. The test and analysis for the linear buck converter was done using setup. The output measurements indicate that the power supply is functional. The measured output values results of the test circuit. The developed output power supply unit is important in measurements, laboratories and test setup. It is implemented for all general applications that require power supply unit. XL6009 module is a DC to DC BUCK-BOOST converter module that operates at a switching frequency of 400kHz. In such high frequency, it provides smaller sized filter components compared with low frequency switching regulators. An improved SingleStage Buck-Boost inverter is provided, using only three or four power semiconductor switches. The inverter can handle a wide range of dc input voltages and produce a fixed ac output voltage. The inverter is well suited to distributed power generation systems such as photovoltaic and wind power and fuel cells, for standalone or grid connected applications. The inverter has a single charge loop, a positive discharge loop and a negative discharge loop. In this complete design of the converter is carried out. This application report gives details regarding this conversion with examples

Twenty-Five Years of Single-Stage Buck–Boost Inverters: Development and Challenges

Single-stage buck–boost inverters have overcome the shortcomings posed by conventional voltage source inverters (VSI) and current source inverters (CSI). VSIs can produce only ac waveforms with a value less than or equal to the applied dc-link voltage (the buck mode), and CSIs can produce only ac waveforms with values greater than or equal to the applied dc-link voltage (the boost mode). On the other hand, single-stage buck–boost inverters can provide a stepped-up/down output voltage, thus accommodating a wide input voltage range. The literature claims single-stage buck–boost inverters are more efficient, less bulky, and able to operate across a wide input voltage range. So why does the industry still love conventional VSIs with a back-ended dc–dc converter or a step-up transformer?

Derivation of OCC Modulator for Grid-Tied Single-Stage Buck-Boost Inverter Operating in the Discontinuous Conduction Mode

This paper is concerned with the derivation of a one-cycle controller for driving a single-stage buck-boost DC-AC micro-inverter in grid-tied applications. The topology under study is based on a full-bridge switch arrangement with no unfolder circuit. The proposed micro-inverter attains a high gain by applying a multi-winding tapped inductor and, therefore, can operate at grid-level voltage without using a DC-DC step-up stage. To minimize the switching loss, the proposed inverter is operated in the discontinuous conduction mode. The operation principles of the proposed topology in the discontinuous conduction mode are discussed and analyzed. Based on the analysis, the one-cycle control law and modulator circuitry needed to control the proposed micro-inverter are developed. The feasibility of the proposed modulation scheme is verified by simulation.

Novel Transformerless Buck–Boost Inverters Without Leakage Current

This article presents novel transformerless single-stage buck-boost inverters with reactive power flow capability. The common-mode voltage of the proposed inverters is constant, which results in negligible leakage current. The output current of the proposed inverters is continuous that lowers the output harmonics and size of the output filtering capacitor. In the proposed inverters, only two switches receive high-frequency switching signals at a time, which reduces the power loss. The proposed topologies can achieve efficient power conversion with a wide input voltage range. A 120-Vrms/60-Hz output voltage, 74–200-V input voltage, and 500-W output power hardware prototype of the proposed inverter is built and tested with resistive, partially inductive, and partially capacitive loads. A peak efficiency of 97.3% is obtained.

Novel Family of Single-Stage Buck–Boost Inverters Based on Unfolding Circuit

This paper describes a novel family of single-phase single-stage buck–boost inverters using output unfolding circuits. Operation principles and component design guidelines along with modulation techniques are presented and discussed. The simulation results confirm all theoretical statements. Experimental setup of the most promising solution is assembled and tested, where the efficiency for different operation modes is analyzed. Finally, the pros and cons along with applications of the proposed solutions are discussed in the conclusions.

Dual-Buck-Structured High-Reliability and High-Efficiency Single-Stage Buck–Boost Inverters

In this paper, dual-buck structured single-stage buck–boost inverters that use power MOSFETs to achieve high efficiency are presented. The proposed inverters require fewer switches, and half of the switches have reduced current stresses. They have no shoot-through problem; therefore, high system reliability can be obtained. The dead-time in PWM signals can be minimized or eliminated, which improving the quality of the output ac voltages and increasing the efficiency. In the proposed inverters, MOSFETs can be used without reverse-recovery issues of their body diodes to boost the efficiency and increase the switching frequency. To further improve the efficiency and stability of the proposed single-phase inverter, PWM strategies combining high- and low-frequency modulation are presented. A hardware prototype of the single-phase inverter was built and tested using resistive, inductive, and nonlinear loads. Experimental results for a 300-W prototype inverter show a 97.4% peak efficiency with a 25 kHz switching frequency.

A Highly Reliable and High-Efficiency Quasi Single-Stage Buck–Boost Inverter

To regulate an output ac voltage in inverter systems having wide input dc voltage variation, a buck–boost power conditioning system is preferred. This paper proposes a novel high-efficiency quasi single-stage single-phase buck–boost inverter. The proposed inverter can solve current shoot-through problem and eliminate PWM dead time, which leads to greatly enhanced system reliability. It allows bidirectional power flow and can use MOSFET as switching device without body diode conducting. The reverse recovery issues and related loss of the MOSFET body diode can be eliminated. The use of MOSFET contributes to the reduction of switching and conduction losses. Also, the proposed inverter can be operated with simple pulse width modulation (PWM) control and can be designed at higher switching frequency to reduce the volume of passive components. The detailed experimental results are provided to show the advantages of the proposed inverter. Efficiency measurement shows that using simple PWM control the proposed inverter can obtain peak efficiency of 97.8% for 1.1-kW output power at 30-kHz switching frequency.

A Comparison Between Single-Phase Quasi- <inline-formula> <tex-math notation="LaTeX">$Z$</tex-math></inline-formula>-Source and Quasi-Switched Boost Inverters

The properties of a single-phase quasi- $Z$ -source inverter (qZSI) and a single-phase quasi-switched boost inverter (qSBI), both of which are single-stage buck-boost inverters, are investigated and compared. For the same operating conditions, qSBI has the following advantages over qZSI: 1) Three capacitors are saved; 2) the current rating on both of its switches and diodes is lower; 3) its boost factor is higher with an equivalent parasitic effect; and 4) its efficiency is higher. However, qSBI has one more active switch and one more diode than $Z$ -source/qZSIs. In additi on, the capacitor voltage stress of qSBI is higher than that of qZSI. The dc and ac component circuit analysis, impedance design with low-frequency and high-frequency ripples, component stresses, and power loss calculation are presented. A prototype based on a TMS320F28335 DSP is built in order to compare the operating principle of qSBI and qZSI.

Isolated discontinuous energy pump‐source inverters

Recently, several single-stage buck-boost inverters, such as Z-source inverter (ZSI), Luo-source inverter and Cuk-source inverter, have been developed. These inverters are considered as discontinuous energy pump-source inverters (DEPSI), since these inverters benefit from a pump circuit with discontinuous output voltage as front-end stage. Considering the concept, this study adds two new converters (Zeta and Forward-source inverters) to this family and compares DEPSIs (including already investigated and the presented inverters) and two-stage converters using DC/DC converter as the boost stage regarding several criteria: 1 - boost capability, 2 - cost, 3 - efficiency and 4 - passive components requirement. The results are discussed to determine the appropriate topology according to different voltage gains. Also, a new control algorithm called minimum constant boost control for optimum control of Luo, Cuk and Zeta source inverters has been proposed here, which is used in the analysis and comparison. Experimental tests for a 250 W prototype of the converters are performed, which confirm the simulations and theoretical results.

Extended-Boost $Z$-Source Inverters

The Z-source inverter has gained popularity as a single-stage buck-boost inverter topology among many researchers. However, its boosting capability could be limited, and therefore, it may not be suitable for some applications requiring very high boost demand of cascading other dc-dc boost converters. This could lose the efficiency and demand more sensing for controlling the added new stages. This paper is proposing a new family of extended-boost quasi Z -source inverter (ZSI) to fill the research gap left in the development of ZSI. These new topologies can be operated with same modulation methods that were developed for original ZSI. Also, they have the same number of active switches as original ZSI preserving the single-stage nature of ZSI. Proposed topologies are analyzed in the steady state and their performances are validated using simulated results obtained in MATLAB/Simulink. Furthermore, they are experimentally validated with results obtained from a prototype developed in the laboratory.

Z-Source-Inverter-Based Flexible Distributed Generation System Solution for Grid Power Quality Improvement

Distributed generation (DG) systems are usually connected to the grid using power electronic converters. Power delivered from such DG sources depends on factors like energy availability and load demand. The converters used in power conversion do not operate with their full capacity all the time. The unused or remaining capacity of the converters could be used to provide some ancillary functions like harmonic and unbalance mitigation of the power distribution system. As some of these DG sources have wide operating ranges, they need special power converters for grid interfacing. Being a single-stage buck-boost inverter, recently proposed Z-source inverter (ZSI) is a good candidate for future DG systems. This paper presents a controller design for a ZSI-based DG system to improve power quality of distribution systems. The proposed control method is tested with simulation results obtained using Matlab/Simulink/PLECS and subsequently it is experimentally validated using a laboratory prototype.