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Author

Yang Yang

Other affiliations: Nanjing University
Bio: Yang Yang is an academic researcher from Nanjing University of Aeronautics and Astronautics. The author has contributed to research in topics: Battery (electricity) & Power factor. The author has an hindex of 7, co-authored 9 publications receiving 720 citations. Previous affiliations of Yang Yang include Nanjing University.

Papers
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Journal ArticleDOI
Shu Wang1, Xinbo Ruan1, Kai Yao1, Siew-Chong Tan, Yang Yang1, Zhihong Ye 
16 Dec 2011
TL;DR: In this paper, a flick-free electrolytic capacitor-less single-phase ac-dc driver for LED lighting is proposed, which consists of an electrolytic capacitive-less PFC converter and a bidirectional converter, which serves to absorb the ac component of the pulsating current of the PFC converters.
Abstract: The electrolytic capacitor is the key component that limits the operating lifetime of LED drivers. If an ac-dc LED driver with power factor correction (PFC) control is allowed to output a pulsating current for driving the LEDs, the electrolytic capacitor will no longer be required. However, this pulsating current will introduce light flicker that varies at twice the power line frequency. In this paper, a configuration of flicker-free electrolytic capacitor-less single-phase ac-dc driver for LED lighting is proposed. The configuration comprises an electrolytic capacitor-less PFC converter and a bidirectional converter, which serves to absorb the ac component of the pulsating current of the PFC converter, leaving only a dc component to drive the LEDs. The output filter capacitor of the bidirectional converter is intentionally designed to have a large voltage ripple, thus its capacitance can be greatly reduced. Consequently, film capacitors can be used instead of electrolytic capacitors, leading to the realization of a flicker-free ac-dc LED driver that has a long lifetime. The proposed solution is generally applicable to all single-phase PFC converters. A prototype with 48-V, 0.7-A output is constructed and tested. Experimental results are presented to verify the effectiveness of the flick-free electrolytic capacitor-less ac-dc LED driver.

366 citations

Journal ArticleDOI
TL;DR: In this article, a two-phase interleaved critical current mode (CRM) boost power factor correction (PFC) converter with a coupled inductor is analyzed, and the coupling effects on the input current, the inductor current, switching frequency and the flux linkage are separately.
Abstract: Interleaved critical current mode (CRM) boost power factor correction (PFC) converter is widely employed recently for its high power density. In order to further reduce the volume and the copper usage of the magnetic components, two-phase interleaved CRM boost PFC converter with a coupled inductor is analyzed in this paper. The coupling effects on the input current, the inductor current, the switching frequency and the flux linkage are analyzed separately. If the self-inductances and the magnetic core are the same for both coupled and noncoupled inductors, the number of winding turns of coupled inductor is fewer than that of the noncoupled inductor, which implies a lower cost. Although the input current ripple increases a little since coupling, a reduction in the total volume of magnetic components, including the electromagnetic interference filter and the coupled inductor, is possible if the coupling coefficient is made reasonable.

164 citations

Journal ArticleDOI
TL;DR: In this article, a flicker-free electrolytic capacitor-less single-phase ac/dc light emitting diode (LED) driver is investigated, which is composed of a power-factor-correction (PFC) converter and a bidirectional converter.
Abstract: In order to achieve high-efficiency, high-power-factor, high-reliability, and low-cost, a flicker-free electrolytic capacitor-less single-phase ac/dc light emitting diode (LED) driver is investigated in this paper. This driver is composed of a power-factor-correction (PFC) converter and a bidirectional converter. The bidirectional converter is used to absorb the second harmonic component in the output current of the PFC converter, thus producing a pure dc output to drive the LEDs. The spectrum of the output capacitor voltage of the bidirectional converter is analyzed, indicating that the output capacitor voltage contains harmonic components at multiples of twice the line frequency apart from the dc component and second harmonic component. A feed-forward control scheme with a series of calculation operation is proposed to obtain the desired modulation signal, which contains the corresponding harmonic components, to ensure the bidirectional converter fully absorb the second harmonic current in the output of the PFC converter. Finally, a 33.6 W prototype is fabricated and tested in the lab, and the experiment results show that the proposed control scheme greatly reduces the ripple of the LED driving current.

146 citations

Journal ArticleDOI
TL;DR: In this article, a hierarchical active balancing architecture for series-connected lithium-ion batteries is proposed, where the battery string is grouped into different packs and the top layer is introduced to eliminate the coupled influence among the cells in different packs.
Abstract: This paper proposes a hierarchical active balancing architecture for the series-connected lithium-ion batteries. The key point of the architecture is that by grouping the battery string into different packs and introducing the top layer, the coupled influence among the cells in different packs is eliminated, which reduces the required balancing time and the energy loss. The repeated charging and discharging problem is avoided, which is beneficial for increasing the state-of-health. Moreover, the proposed architecture can lower the current rating of the balancing circuits, which helps decrease the required cost and improve the system efficiency. On the basis of the architecture, a balancing control using the state-of-charge of each cell is proposed to achieve the balance for all the cells. Furthermore, to deliver the energy from one pack to any other pack bidirectionally, a multidirectional multiport converter along with the current control method is proposed to serve as the top layer. This converter is different from the conventional three-port converter as it can achieve the arbitrary current flow direction control for any number of ports. The experimental results based on 24 series-connected 200-Ah lithium-ion batteries verified the benefits of the proposed architecture and the balancing circuits. After balancing, 4.1% of the total energy of the battery string is saved. Compared to the conventional adjacent cell-to-cell architecture, the proposed architecture can decrease the balancing time and the energy loss during the balancing process by 27.6% and 44.0%, respectively. In addition, the current rating and the cost of the balancing circuits in the proposed architecture is only 37.5% and 11.5% of that in other references.

127 citations

Patent
12 Oct 2016
TL;DR: In this article, an adaptive extended Kalman filtering (ALF) estimation method was proposed for series-wound battery packs with an equalization circuit, which is applicable to active equalization and passive equalization.
Abstract: The invention relates to an SOC estimation method for a series-wound battery pack having an equalization circuit. According to the estimation method, adaptive extended Kalman filtering SOC estimation is carried out on the single batteries with the lowest voltage or the highest voltage in the charge-discharge stage so as to obtain the SOC of the series-wound battery pack. For eliminating influence on the measurement signal from noise, and for analyzing the unstable and sharply-changed voltage and current signals, wavelet transform is performed before the implementation of the adaptive extended Kalman filtering so as to realize denoising and analyzing of the signal; and the condition that the curves of the battery parameters and the open circuit voltage-state of charge (OCV-SOC) are changed along with the changes of temperatures and the changes of the SOC is taken into consideration. By adoption of the estimation method, online updating of the parameters can be performed, so that the SOC estimation precision can be improved; the SOC of the battery pack can be accurately estimated under the premise of ensuring the safety operation of the series-wound battery pack; therefore, the estimation method is applicable to active equalization and passive equalization; and meanwhile, by adoption of the estimation method, the influence from noise can be effectively eliminated, and the voltage and current signals can be effectively analyzed.

24 citations


Cited by
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Journal ArticleDOI
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

Journal ArticleDOI
Yao Sun1, Yonglu Liu1, Mei Su1, Wenjing Xiong1, Jian Yang1 
TL;DR: In this paper, the authors provide a comprehensive review of active power decoupling circuit topologies and their development laws from the view of the dual principle, switch sharing, and differential connection.
Abstract: Active power decoupling methods are developed to deal with the inherent ripple power at twice the grid frequency in single-phase systems generally by adding active switches and energy storage units. They have obtained a wide range of applications, such as photovoltaic (PV) systems, light-emitting diodes (LEDs) drivers, fuel cell (FC) power systems, and electric vehicle (EV) battery chargers, etc. This paper provides a comprehensive review of active power decoupling circuit topologies. They are categorized into two groups in terms of the structure characteristics: independent and dependent decoupling circuit topologies. The former operates independently with the original converter, and the latter, however, shares the power semiconductor devices with the original converter partially and even completely. The development laws for the active power decoupling topologies are revealed from the view of “duality principle,” “switches sharing,” and “differential connection.” In addition, the exceptions and special cases are also briefly introduced. This paper is targeted to help researchers, engineers, and designers to construct some new decoupling circuit topologies and properly select existing ones according to the specific application.

395 citations

Journal ArticleDOI
TL;DR: The topological derivation of H-SLCs is deduced by combining the passive and active switched-inductor unit and the operation modes of the proposed asymmetrical and symmetrical converters are illustrated.
Abstract: In applications where the high voltage gain is required, such as photovoltaic grid-connected system, fuel-cell and high-intensity discharge lamps for automobile, high step-up dc-dc converters have been introduced to boost the low voltage to a high bus voltage. The voltage gain of traditional boost converter is limited, considering the issues such as the system efficiency and current ripple. This paper proposes a class of hybrid switched-inductor converters (H-SLCs) for high step-up voltage gain conversion. First, the topological derivation of H-SLCs is deduced by combining the passive and active switched-inductor unit; second, this paper illustrates the operation modes of the proposed asymmetrical and symmetrical converters; third, the performance of the proposed converters is analyzed in detail and compared with existing converters; finally, a prototype is established in the laboratory, and the experimental results are given to verify the correctness of the analysis.

320 citations

Journal ArticleDOI
TL;DR: A review of state of charge (SoC) estimation for lithium-ion batteries is presented in this article, focusing on the description of the techniques and the elaboration of their weaknesses for the use in online battery management systems (BMS) applications.
Abstract: Energy storage emerged as a top concern for the modern cities, and the choice of the lithium-ion chemistry battery technology as an effective solution for storage applications proved to be a highly efficient option. State of charge (SoC) represents the available battery capacity and is one of the most important states that need to be monitored to optimize the performance and extend the lifetime of batteries. This review summarizes the methods for SoC estimation for lithium-ion batteries (LiBs). The SoC estimation methods are presented focusing on the description of the techniques and the elaboration of their weaknesses for the use in on-line battery management systems (BMS) applications. SoC estimation is a challenging task hindered by considerable changes in battery characteristics over its lifetime due to aging and to the distinct nonlinear behavior. This has led scholars to propose different methods that clearly raised the challenge of establishing a relationship between the accuracy and robustness of the methods, and their low complexity to be implemented. This paper publishes an exhaustive review of the works presented during the last five years, where the tendency of the estimation techniques has been oriented toward a mixture of probabilistic techniques and some artificial intelligence.

219 citations

Journal ArticleDOI
TL;DR: Based on a survey on over 1400 commercial LED drivers and a literature review, a range of LED driver topologies are classified according to their applications, power ratings, performance and their energy storage and regulatory requirements as discussed by the authors.
Abstract: Based on a survey on over 1400 commercial LED drivers and a literature review, a range of LED driver topologies are classified according to their applications, power ratings, performance and their energy storage and regulatory requirements. Both passive and active LED drivers are included in the review and their advantages and disadvantages are discussed. This paper also presents an overall view on the technical and cost aspects of the LED technology, which is useful to both researchers and engineers in the lighting industry. Some general guidelines for selecting driver topologies are included to aid design engineers to make appropriate choices.

210 citations