Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

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A review of single-phase improved power quality AC-DC converters

DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

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Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

The photovoltaic (PV) grid-connected power system in the residential applications is becoming a fast growing segment in the PV market due to the shortage of the fossil fuel energy and the great environmental pollution. A new research trend in the residential generation system is to employ the PV parallel-connected configuration rather than the series-connected configuration to satisfy the safety requirements and to make full use of the PV generated power. How to achieve high-step-up, low-cost, and high-efficiency dc/dc conversion is the major consideration due to the low PV output voltage with the parallel-connected structure. The limitations of the conventional boost converters in these applications are analyzed. Then, most of the topologies with high-step-up, low-cost, and high-efficiency performance are covered and classified into several categories. The advantages and disadvantages of these converters are discussed. Furthermore, a general conceptual circuit for high-step-up, low-cost, and high-efficiency dc/dc conversion is proposed to derive the next-generation topologies for the PV grid-connected power system. Finally, the major challenges of high-step-up, low-cost, and high-efficiency dc/dc converters are summarized. This paper would like to make a clear picture on the general law and framework for the next-generation nonisolated high-step-up dc/dc converters.

Review of Nonisolated High-Step-Up DC/DC Converters in Photovoltaic Grid-Connected Applications

New recommendations and future standards have increased the interest in power factor correction circuits. There are multiple solutions in which line current is sinusoidal. In addition, a great number of circuits have been proposed with nonsinusoidal line current. In this paper, a review of the most interesting solutions for single phase and low power applications is carried out. They are classified attending to the line current waveform, energy processing, number of switches, control loops, etc. The major advantages and disadvantages are highlighted and the field of application is found.

Single phase power factor correction: a survey

A new family of single stage isolated power-factor correctors features fast regulation of the output voltage, one or two power switches operated in unison, a single control loop, and automatic shaping of the line current. We give topologies, steady-state analysis, design considerations, and experimental results. >

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A new family of single-stage isolated power-factor correctors with fast regulation of the output voltage

A family of AC-to-DC converters which integrate the functions of low harmonic rectification, low frequency energy storage, and wide bandwidth output voltage control into a single converter containing one, two, or four active switches is presented. These converters utilize a discontinuous conduction mode input inductor, an internal energy storage capacitor, and transformer secondary circuits which resemble the bridge, forward, flyback, or Cuk DC-DC converters. A large-signal equivalent circuit model for this family which uses the loss-free resistor concept is presented. Design strategies and experimental results are given. High performance regulation with satisfactory line current harmonics is demonstrated with conventional duty ratio control. Further improvements in line current are possible by simultaneous duty ratio and switching frequency control. >

Integrated high quality rectifier-regulators

A new family of a single-switch three-diode dc-dc pulsewidth-modulated (PWM) converters operating at constant frequency and constant duty cycle is presented in this paper. The proposed converters are different from the conventional dc-dc step-up converters, and they posses higher voltage gain with small output voltage ripples. Other advantages of the proposed converters include lower voltage stress on the semiconductor devices, simple structure, and control. Moreover, the reduced voltage stress on the diodes allows using Schottky diodes for alleviating the reverse-recovery current problem, as well as decreasing the switching and conduction losses. The principle of operation, theoretical analysis, and experimental results of one prototype rated 40 W and operating at 94 kHz are provided in this paper to verify the performance of this new family of converters.

A Family of Single-Switch PWM Converters With High Step-Up Conversion Ratio

New bridgeless single-phase ac-dc power factor correction (PFC) rectifiers based on Sepic and Cuk topologies are proposed. The absence of an input diode bridge and the presence of only two semiconductor switches in the current flowing path during each switching cycle result in less conduction losses and improved thermal management compared to the conventional Sepic and Cuk PFC converters. The proposed topologies are designed to work in discontinuous conduction mode (DCM) to achieve almost unity power factor in a simple and effective manner. The DCM operation gives additional advantages such as zero-current turn-on in the power switches, zero-current turn-off in the output diode and reduces the complexity of the control circuitry. The proposed rectifiers are theoretically investigated. Performance comparisons between the proposed and conventional Sepic PFC rectifiers are performed. Simulation and experimental results are provided for a design example of a 65-W/48-V at 100- Vrms line voltage to evaluate the performance of the proposed PFC rectifier.

New Bridgeless DCM Sepic and Cuk PFC Rectifiers With Low Conduction and Switching Losses

In this paper, a new bridgeless single-phase AC-DC converter with an automatic power factor correction (PFC) is proposed. The proposed rectifier is based on the single-ended primary inductance converter (SEPIC) topology and it utilizes a bidirectional switch and two fast diodes. The absence of an input diode bridge and the presence of only one diode in the flowing-current path during each switching cycle result in less conduction loss and improved thermal management compared to existing PFC rectifiers. Other advantages include simple control circuitry, reduced switch voltage stress, and low electromagnetic-interference noise. Performance comparison between the proposed and the conventional SEPIC PFC rectifier is performed. Simulation and experimental results are presented to demonstrate the feasibility of the proposed technique.

Bridgeless SEPIC Rectifier With Unity Power Factor and Reduced Conduction Losses

Three new bridgeless single-phase ac-dc power factor correction (PFC) rectifiers based on Cuk topology are proposed. The absence of an input diode bridge and the presence of only two semiconductor switches in the current flowing path during each interval of the switching cycle result in less conduction losses and an improved thermal management compared to the conventional Cuk PFC rectifier. The proposed topologies are designed to work in discontinuous conduction mode (DCM) to achieve almost a unity power factor and low total harmonic distortion of the input current. The DCM operation gives additional advantages such as zero-current turn-ON in the power switches, zero-current turn-OFF in the output diode, and simple control circuitry. Performance comparisons between the proposed and conventional Cuk PFC rectifiers are performed based on circuit simulations. Experimental results for a 150 W/48 Vdc at 100 Vrms line voltage to evaluate the performance of the proposed bridgeless PFC rectifiers are provided.

Esam H. Ismail

Papers

Integrated high quality rectifier-regulators

A Family of Single-Switch PWM Converters With High Step-Up Conversion Ratio

New Bridgeless DCM Sepic and Cuk PFC Rectifiers With Low Conduction and Switching Losses

Bridgeless SEPIC Rectifier With Unity Power Factor and Reduced Conduction Losses

New Efficient Bridgeless Cuk Rectifiers for PFC Applications