A Novel Buck–Boost AC–AC Converter With Both Inverting and Noninverting Operations and Without Commutation Problem (original) (raw)
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A new AC – AC converter with buck and boost options
European Journal of Electrical Engineering, 2018
This paper proposes a novel AC-AC converter capable of operating in noninverting and inverting buck boost modes. The projected AC-AC converter uses six IGBTs with reverse blocking capability, two capacitors and one inductor. The main advantage of this AC-AC converter is that it is free from shoot through problem even when all the six IGBTs are in ON condition. Hence dead time between two pulse width modulation signals is not necessary, which results in load voltage waveform with very less Total Harmonic Distortion (THD). Furthermore elimination of dead time, eradicates the commutation problem even in the absence of hefty snubbers or with soft commutation methods. The switching losses of the proposed converter are very less since only two devices are switched at high frequency that too only in a half cycle. The remaining switches are switched at fundamental frequency, which in turn increases the efficiency of the converter. The proposed converter is a suitable candidature in dynamic voltage restorer and single phase solid state transformer applications. RÉSUMÉ. Cet article propose un nouveau convertisseur CA-CA capable de fonctionner en modes Buck-Boost non inversé et inversé. Le convertisseur CA-CA projeté utilise le transistor bipolaire à grille isolée (IGBT, de l'anglais Insulated Gate Bipolar Transistor) avec la capacité de blocage inverse, deux condensateurs et un inducteur. Le principal avantage de ce convertisseur CA-CA réside dans le fait qu'il ne présente aucun problème de dé clenchement, mê me lorsque les six-IGBT sont activé s. Par consé quent, le temps mort entre les deux signaux modulé s en largeur d'impulsion n'est pas requis, ce qui entraî ne taux trè s bas de distorsion harmonique (THD, de l'anglais total harmonic distortion) de la forme d'onde de la tension de charge. De plus, le temps mort peut ê tre é liminé et le problè me de commutation peut ê tre é liminé mê me sans un grand nombre d'amortisseurs ou une méthode de commutation douce. Les pertes de commutation du convertisseur proposé sont trè s faibles car seuls deux appareils sont commuté s à haute fré quence, ce qui ne repré sente qu'un demicycle. Les autres commutateurs sont commuté s à la fré quence fondamentale, ce qui augmente 296 EJEE. Volume 20-n° 3/2018 l'efficacité du convertisseur. Le convertisseur proposé convient parfaitement aux applications de restauration dynamique de la tension et de transformateurs à à l'é tat solide monophasé KEYWORDS: commutation, AC-AC converter, buck-boost modes, inverting and non-inverting.
An Enhanced Power DC-Ac Buck Converter
DYNA ENERGIA Y SOSTENIBILIDAD
ABSTRACT: This paper presents an enhanced power DC-AC buck converter.The main aim of this research paper is to ensure that the conventional H-bridge DC-AC buck converter is operated practically without delay time between the complementary power switches on the same leg.The enhanced version is realized by serially connecting sized inductor-capacitor-diode topology between the drains and the sources of the high sides of the H-bridge converters. The significant improvement in this kind of converter is that it offers short-circuit immune systems that are not obtainable in the traditional buck DC-AC converter and it triggers the complementary power switches without delay time. The power circuit is obtained by an amalgamation of two Y-closed-up topologies to form an H-bridge converter. The proposed system has a power rating of 3.25 kW, THD of 0.2717%, and pure sine waveforms of output voltage and currentof 311.00V and 10.63A under resistive loads. Under RL loads, it offers 3.25 kW, THD of...
ERJ. Engineering Research Journal
A single-phase direct pulse width modulation (PWM) AC-AC converter is proposed in this paper. The proposed converter has a simple structure and efficient performance to be utilized as an AC voltage buck converter. It is designed with a low number of semiconductor switches and passive components (four switches, one inductor, and one capacitor). The major advantages of the proposed converter can be mentioned as: Only one switch operates during each mode of operation decreasing the circuit losses. It is operated with simple pulse width modulation control and doesn't require a safe-commutation strategy. It does not suffer from input source shoot-through and dead time problems. It retains the common sharing ground of the input and output and can be utilized for voltage sag and swell compensation. Additionally, the proposed converter features are high efficiency, continuous input and output currents, and low filtering requirements. The performance of the proposed circuit is extensively evaluated by using MATLAB/Simulink environment. Moreover, a DSP-based laboratory model is built for physical realization of the proposed converter operation.
Energies
In this research, a new single-phase direct AC-to-AC converter, operating in buck and boost mode, with a bipolar voltage gain, is proposed. The operation is accomplished through high frequency direct and indirect PWM control of a single switch with low voltage stresses. This reduces, not only the control effort, but also the switching losses. The low voltage stresses across the high frequency switches, reduce the dv/dt problem significantly without any loss and bulky voltage snubber arrangement. The operation, in its all-operating modes, has a low inductor ripple current and switching current. The proposed converter may be employed as an AC voltage restorer in a power distribution system to cope with the voltage sag and swell issues. The detailed analysis of the proposed converter is carried out in order to compare its performance with the existing converters. The simulation results obtained using the MATLAB/Simulink environment are verified through experimental results.
Reducing in size and number of active elements has been an important consideration in designing of the converters. There have been several attempts to achieve a better structure for inverters having less THD. In this paper, a novel structure has been proposed for DC-DC converters utilizing two switches to decrease the number of active elements. By the use of a simple switching method, the DC input voltage is divided into three voltages with different frequencies and amplitudes which have the frequency of zero (DC voltage), fundamental frequency, and switching frequency. To obtain an AC sinusoidal output, DC and switching frequency is eliminated by using two filters. Comparing to a conventional full bridge inverters, this structure reduces two active elements. In this proposed method, the total harmonic distortion (THD) has been greatly decreased and the efficiency is improved. Simulations have been carried out and the obtained results confirm the mentioned goals.
Boost & Buck-Boost Derived Hybrid Converter for Simultaneous DC & AC Applications
2014
This Paper introduces new hybrid converter topologies which can supply simultaneously AC as well as DC from a single DC source. The new Hybrid Converter is derived from the single switch controlled Boost and Buck-Boost converter by replacing the controlled switch with voltage source inverter (VSI). This new hybrid converter has the advantages like reduced number of switches as compared with conventional design having separate converter for supplying AC and DC loads, provide DC and AC outputs with an increased reliability, resulting from the inherent shoot through protection in the inverter stage. For controlling switches PWM control, based upon unipolar Sine-PWM is described. Simulink model is used to validate the operation of the converter. The proposed Converter can supply DC and AC loads at 190 V and 48 V (rms) respectively from a 48 V DC source.
Cascaded Dual-Buck AC–AC Converter With Reduced Number of Inductors
IEEE Transactions on Power Electronics, 2017
This paper proposes new type of cascaded ac-ac converter with phase-shift control and reduced number of inductors. It can attain high voltage levels by using standard low-voltage rating semiconductor devices. The proposed converter is resistant to current shoot-through and does not require pulse-width modulation (PWM) dead-time; these lead to greatly enhanced system reliability and effective utilization of PWM voltages. Moreover, it does not require current/voltage polarity sensors, lossy snubbers, or dedicated PWM strategies for commutation. These features make it possible to design the converter with reduced control complexity, and obtain output voltage with less distortion. The cascaded units in the proposed converter share the inductors; therefore, number of inductors, inductors footprints, and magnetic volume can be reduced. The phase-shift PWM control is also presented. It increases the effective frequency of the converter by the number of cascaded units, which decreases the size of the passive components and/or the current and voltage ripples. In order to demonstrate the advantages of the proposed converter, detailed comparative simulations and experimental results of the proposed 2-unit, 3-unit, and 4-unit cascaded converters are provided.
Unified Non-Inverting and Inverting PWM AC–AC Converter With Versatile Modes of Operation
IEEE Transactions on Industrial Electronics, 2017
This paper proposes unified non-inverting and inverting AC-AC converter (UNI-AC) using pulse width modulation (PWM) for the utility voltage compensation. It offers four effective switching states to regulate the output voltage in bipolar manner, facilitating versatile modes of operation with different number of switching states being modulated. Each mode of the proposed UNI-AC is able to compensate both the grid voltage sag and swell problems due to its bipolar voltage gain. The operational principle and comparison for all these modes are investigated in details. Also, the UNI-AC is reversible and compatible with full range of power factor. Other technical merits offered by the proposed approach include the compact hardware installation, reduced switch voltage stress (also low dv/dt) and decreased control complexity. Detailed analysis and experimental verification are presented in this paper. Index Terms-Bipolar voltage gain, PWM direct ac-ac converter, utility voltage compensation, versatile modes of operation.
Implementation of a low cost ac-dc converter for high and low power applications
International journal of engineering and technology, 2017
This paper proposes an ac-dc converter that gives multiple outputs capable of feeding both high and low power applications. The input ac supply is converted to dc by a diode bridge rectifier, filtered and fed to a modified multiport converter (MPC). This paper focuses on the design of the modified multiport converter that has a cascaded combination of zeta and a buck converter. This is designed as a single input and multiple output converter (SIMO) structure which can operate two loads, one with a high power and other with a low power application, depending on the time instant. The need for opting a multiport converter, reduces the number of switches utilized, thereby reducing the switching losses in the circuit. The zeta in the MPC boosts the input voltage and the buck converter reduces the input voltage and is accordingly fed to the need of the load. The design of the components have been analysed through steady state. MATLAB Simulink has been used to simulate the converter circui...
A boost DC-AC converter: analysis, design, and experimentation
IEEE Transactions on Power Electronics, 1999
This paper proposes a new voltage source inverter (VSI) referred to as a boost inverter or boost DC-AC converter. The main attribute of the new inverter topology is the fact that it generates an AC output voltage larger than the DC input one, depending on the instantaneous duty cycle. This property is not found in the classical VSI, which produces an AC output instantaneous voltage always lower than the DC input one. For the purpose of optimizing the boost inverter dynamics, while ensuring correct operation in any working condition, a sliding mode controller is proposed. The main advantage of the sliding mode control over the classical control schemes is its robustness for plant parameter variations, which leads to invariant dynamics and steady-state response in the ideal case. Operation, analysis, control strategy, and experimental results are included in this paper. The new inverter is intended to be used in uninterruptible power supply (UPS) and AC driver systems design whenever an AC voltage larger than the DC link voltage is needed, with no need of a second power conversion stage