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Author

Haibing Hu

Bio: Haibing Hu is an academic researcher from Nanjing University of Aeronautics and Astronautics. The author has contributed to research in topics: Inverter & Solar micro-inverter. The author has an hindex of 30, co-authored 132 publications receiving 4086 citations. Previous affiliations of Haibing Hu include Nanjing University & University of Central Florida.


Papers
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TL;DR: In this paper, a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications is presented, compared and scrutinized in scope of the size of decoupled capacitor, efficiency, and control complexity.
Abstract: The reliability of the microinverter is a very important feature that will determine the reliability of the ac-module photovoltaic (PV) system. Recently, many topologies and techniques have been proposed to improve its reliability. This paper presents a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications. These power decoupling techniques are categorized into three groups in terms of the decoupling capacitor locations: 1) PV-side decoupling; 2) dc-link decoupling; and 3) ac-side decoupling. Various techniques and topologies are presented, compared, and scrutinized in scope of the size of decoupling capacitor, efficiency, and control complexity. Also, a systematic performance comparison is presented for potential power decoupling topologies and techniques.

458 citations

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TL;DR: In this article, the relations of space-vector modulation (SVM) and carrier-based PWM for multilevel inverter were studied, and an improved PWM scheme was proposed based on modulation waves of three-level SVM, which reserves the main advantages of SVM and can be achieved easily.
Abstract: This paper studies the relations of space-vector modulation (SVM) and carrier-based pulse-width modulation (PWM) for multilevel inverter. The PWMs' generation of SVM can be achieved by carrier-based PWM scheme, but the modulated wave of SVM is acquired by vectors' calculations and switching-states' selection. Based on different selection of redundant switching-states, there are many types of SVM modulated waves, some of which can function equivalently through proper selection of common-mode injections in the case of carrier-based PWM, the others have more freedoms in switching-states' selection than carrier-based PWM. Selection of more switching-states in SVM is propitious to optimize the output voltage, balance the dc power and so on. Then an improved PWM scheme is proposed based on the modulation waves of three-level SVM, which reserves the main advantages of SVM, and can be achieved easily. Finally, a five-level test circuit is built to verify this PWM scheme.

344 citations

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TL;DR: In this article, a generalized mode analysis is presented that provides highly accurate prediction on resonant current and voltage behavior and dc gain characteristic, and an approximation method is developed to estimate the peak gain point, which is useful in LLC design.
Abstract: With the advantage of achieving zero voltage switching for a wide input voltage range, the LLC resonant topology has become increasingly popular for use in high power density and high-efficiency power converter applications. However, when the LLC converter is applied to wide input voltage range applications, the widely used fundamental harmonic approximation is incapable of guiding the design due to its inaccuracy. Thus an accurate LLC converter model is desired. In this paper, a generalized mode analysis is presented that provides highly accurate prediction on resonant current and voltage behavior and dc gain characteristic. Also, because operation modes are affected by load, frequency, and gain conditions, the boundaries and distribution of modes are discussed and illustrated. Based on the mode analysis, an approximation method is developed to estimate the peak gain point, which is useful in LLC design. This approximation demonstrates high accuracy within the simulation results. An experimental prototype is built to verify the analysis.

337 citations

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TL;DR: In this article, the authors provide an introduction, review, and framework for the category of high-step-up coupled-inductor boost converters, which are categorized into five groups according to the major topological features.
Abstract: High-step-up, high-efficiency, and cost-effective dc–dc converters, serving as an interfacing cell to boost the low-voltage output of renewable sources to the utility voltage level, are an important part in renewable energy systems. Over the past few years, there has been a substantial amount of studies devoted to high-step-up dc–dc converters. Among them, the category of coupled-inductor boost converters is widely researched and considered to be a promising solution for high-step-up applications. In this paper, these converters are categorized into five groups according to the major topological features. The derivation process, advantages, and disadvantages of these converters are systematically discussed, compared, and scrutinized. This paper aims to provide an introduction, review, and framework for the category of high-step-up coupled-inductor boost converters. General structures for the topologies are proposed to clarify the topological derivation process and to show potential gaps. Furthermore, challenges or directions are presented in this paper for deriving new topologies in this field.

325 citations

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TL;DR: In this paper, a modified LLC converter with two transformers in series, which has four operation configurations, covering the range of four times the minimum input voltage, is proposed to minimize the magnetizing current and thus minimize the conduction and core losses.
Abstract: This paper proposed a modified LLC converter with two transformers in series, which has four operation configurations, covering the range of four times the minimum input voltage. To optimize the proposed LLC converter in an attempt to achieve good efficiency, a numerical method is developed based on the LLC converter's steady-state equations. In order to minimize the magnetizing current and thus minimize the conduction and core losses, an optimal objective is proposed to find the maximum magnetizing inductance. An optimization procedure and a design example are given. A 250-W 210-V output prototype with input voltage ranging from 25 to 100 V is built to verify the developed numerical model and optimal design method. The dc gain obtained from experimental data agrees pretty well with that from the developed numerical model. Two conventional LLC converters are designed using fundamental harmonic approximation and the proposed optimal design, respectively, to make comparison with the proposed LLC converter and validate the proposed optimal design. Experimental results show that the proposed converter with proposed optimal design can achieve the peak efficiency up to 98%, while maintaining a very wide input voltage range.

280 citations


Cited by
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TL;DR: The basic operation and the most used modulation and control techniques developed to date of neutral-point-clamped inverters are presented and some technological problems such as capacitor balance and losses are presented.
Abstract: Neutral-point-clamped (NPC) inverters are the most widely used topology of multilevel inverters in high-power applications (several megawatts). This paper presents in a very simple way the basic operation and the most used modulation and control techniques developed to date. Special attention is paid to the loss distribution in semiconductors, and an active NPC inverter is presented to overcome this problem. This paper discusses the main fields of application and presents some technological problems such as capacitor balance and losses.

1,556 citations

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TL;DR: In this paper, the authors comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques, and discuss the advantages and disadvantages of these voltage boosting techniques and associated converters.
Abstract: 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.

1,230 citations

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TL;DR: A simple and low-computational-cost modulation technique for multilevel cascaded H-bridge converters based on geometrical considerations considering a unidimensional control region to determine the switching sequence and the corresponding switching times is presented.
Abstract: Multilevel cascaded H-bridge converters have found industrial application in the medium-voltage high-power range. In this paper, a generalized modulation technique for this type of converter based on a multidimensional control region is presented. Using the multidimensional control region, it is shown that all previous modulation techniques are particularized versions of the proposed method. Several possible solutions to develop a specific implementation of the modulation method are addressed in order to show the potential possibilities and the flexibility of the proposed technique. In addition, a feedforward version of this technique is also introduced to determine the switching sequence and the switching times, avoiding low harmonic distortion with unbalanced dc voltages. Experimental results are shown in order to validate the proposed concepts.

941 citations

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TL;DR: In this paper, the most common multilevel inverter topologies and control schemes have been reviewed, and the selection of topology and control techniques may vary according to power demands of inverter.

574 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive review of step-up single-phase non-isolated inverters suitable for ac-module applications is presented, where the selected solutions are designed and simulated complying with the benchmark obtaining passive and semiconductor components ratings.
Abstract: This paper presents a comprehensive review of step-up single-phase non-isolated inverters suitable for ac-module applications. In order to compare the most feasible solutions of the reviewed topologies, a benchmark is set. This benchmark is based on a typical ac-module application considering the requirements for the solar panels and the grid. The selected solutions are designed and simulated complying with the benchmark obtaining passive and semiconductor components ratings in order to perform a comparison in terms of size and cost. A discussion of the analyzed topologies regarding the obtained ratings as well as ground currents is presented. Recommendations for topological solutions complying with the application benchmark are provided.

475 citations