Laszlo Huber

Bio: Laszlo Huber is an academic researcher from Research Triangle Park. The author has contributed to research in topics: Power factor & Rectifier. The author has an hindex of 32, co-authored 71 publications receiving 5106 citations. Previous affiliations of Laszlo Huber include Delta Electronics & University of Novi Sad.

Space vector modulated three-phase to three-phase matrix converter with input power factor correction

Abstract: Analysis, design, and implementation of the space vector modulated three-phase to three-phase matrix converter with input power factor correction are presented. The majority of published research results on the matrix converter control are given an overview, and the one which employs simultaneous output-voltage and input-current space vector modulation, is systematically reviewed. The modulation algorithm is theoretically derived from the desired average transfer functions, using the indirect transfer function approach. The algorithm is verified through implementation of a 2 kVA experimental matrix converter driving a standard induction motor as a load. The switching frequency is 20 kHz. The modulator is implemented with a digital signal processor. The resultant output voltages and input currents are sinusoidal, practically without low-frequency harmonics. The input power factor is above 0.99 in the whole operating range.

Performance Evaluation of Bridgeless PFC Boost Rectifiers

Abstract: In this paper, a systematic review of bridgeless power factor correction (PFC) boost rectifiers, also called dual boost PFC rectifiers, is presented. Performance comparison between the conventional PFC boost rectifier and a representative member of the bridgeless PFC boost rectifier family is performed. Loss analysis and experimental efficiency evaluation for both CCM and DCM/CCM boundary operations are provided.

Performance Evaluation of Bridgeless PFC Boost Rectifiers

Abstract: In this paper, a systematic review of bridgeless PFC boost rectifiers, also called dual boost PFC rectifiers, is presented. Performance comparison between the conventional PFC boost rectifier and a representative member of the bridgeless PFC boost rectifier family is performed. Design considerations and experimental results in both CCM and DCM/CCM boundary operations are provided.

Single-Stage, Universal-Input AC/DC LED Driver With Current-Controlled Variable PFC Boost Inductor

Abstract: This paper presents a single-stage flyback power-factor-correction (PFC) circuit with a variable boost inductance for high-brightness LED applications for the universal input voltage (90-270 Vrms). The proposed circuit overcomes the limitations of the conventional single-stage PFC flyback with a constant boost inductance that cannot be designed to achieve a practical maximum bulk-capacitor voltage level (i.e., less than 450 V) at high line while meeting required line-current harmonic specifications at low line. According to the proposed method for achieving variable boost inductance, the boost inductance has a constant high value at high line, while at low line it is reduced proportionally to the load current, so that the IEC 61000-3-2 class C and corresponding Japanese JIS C 61000-3-2 class C line-current harmonic limits are satisfied. The proposed single-stage PFC flyback LED driver with the variable boost inductor is experimentally verified on a 24-V/91-W prototype circuit.

A design approach for server power supplies for networking applications

Abstract: Present specifications for computer power supplies for networking applications call for designs with dual inputs: the universal AC-line input and the 48-V nominal DC input. In this paper, a design and evaluation of the DC-input version of a 900-W server power supply is presented. The AC-input version of this power supply is leveraged from the AC-input version by using the same output stage, and by replacing the AC front-end in the AC-input version with a DC front end which provides the same input voltage to the output stage. By adopting this design approach, it is possible to achieve design modularity, design standardization, minimize the design time, optimize utilization of resources, and minimize the cost. The DC-input version uses a cascade connection of two DC boost converters because of its superior performance compared with other topologies.

Matrix converters: a technology review

Abstract: The matrix converter is an array of controlled semiconductor switches that connects directly the three-phase source to the three-phase load. This converter has several attractive features that have been investigated in the last two decades. In the last few years, an increase in research work has been observed, bringing this topology closer to the industrial application. This paper presents the state-of-the-art view in the development of this converter, starting with a brief historical review. An important part of the paper is dedicated to a discussion of the most important modulation and control strategies developed recently. Special attention is given to present modern methods developed to solve the commutation problem. Some new arrays of power bidirectional switches integrated in a single module are also presented. Finally, this paper includes some practical issues related to the practical application of this technology, like overvoltage protection, use of filters and ride-through capability.

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

Abstract: 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.

Switched-Capacitor/Switched-Inductor Structures for Getting Transformerless Hybrid DC–DC PWM Converters

Abstract: A few simple switching structures, formed by either two capacitors and two-three diodes (C-switching), or two inductors and two-three diodes (L-switching) are proposed. These structures can be of two types: ldquostep-downrdquo and ldquostep-up.rdquo These blocks are inserted in classical converters: buck, boost, buck-boost, Cuk, Zeta, Sepic. The ldquostep-downrdquo C- or L-switching structures can be combined with the buck, buck-boost, Cuk, Zeta, Sepic converters in order to get a step-down function. When the active switch of the converter is on, the inductors in the L-switching blocks are charged in series or the capacitors in the C-switching blocks are discharged in parallel. When the active switch is off, the inductors in the L-switching blocks are discharged in parallel or the capacitors in the C-switching blocks are charged in series. The ldquostep-uprdquo C- or L-switching structures are combined with the boost, buck-boost, Cuk, Zeta, Sepic converters, to get a step-up function. The steady-state analysis of the new hybrid converters allows for determing their DC line-to-output voltage ratio. The gain formula shows that the hybrid converters are able to reduce/increase the line voltage more times than the original, classical converters. The proposed hybrid converters contain the same number of elements as the quadratic converters. Their performances (DC gain, voltage and current stresses on the active switch and diodes, currents through the inductors) are compared to those of the available quadratic converters. The superiority of the new, hybrid converters is mainly based on less energy in the magnetic field, leading to saving in the size and cost of the inductors, and less current stresses in the switching elements, leading to smaller conduction losses. Experimental results confirm the theoretical analysis.

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

Abstract: 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.

Fundamentals of Power Electronics

Abstract: This chapter gives a description and overview of power electronic technologies including a description of the fundamental systems that are the building blocks of power electronic systems. Technologies that are described include: power semiconductor switching devices, converter circuits that process energy from one DC level to another DC level, converters that produce variable frequency from DC sources, principles of rectifying AC input voltage in uncontrolled DC output voltage and their extension to controlled rectifiers, converters that convert to AC from DC (inverters) or from AC with fixed or variable output frequency (AC controllers, DC–DC–AC converters, matrix converters, or cycloconverters). The chapter also covers control of power converters with focus on pulse width modulation (PWM) control techniques.