Author
William G. Dunford
Other affiliations: University of Toronto, University of Belgrade, Imperial College London
Bio: William G. Dunford is an academic researcher from University of British Columbia. The author has contributed to research in topics: Boost converter & Ćuk converter. The author has an hindex of 27, co-authored 120 publications receiving 4948 citations. Previous affiliations of William G. Dunford include University of Toronto & University of Belgrade.
Topics: Boost converter, Ćuk converter, Power factor, Inductor, Buck converter
Papers published on a yearly basis
Papers
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20 Jun 2004
TL;DR: In this article, a modified adaptive hill climbing (MAHC) MPPT method is introduced, which can be treated as an extension of the traditional hill climbing algorithm, and it can avoid tracking deviation and result in improved performance in both dynamic response and steady-state.
Abstract: Maximum power point tracking (MPPT) must usually be integrated with photovoltaic (PV) power systems so that the photovoltaic arrays are able to deliver maximum available power. In this paper, a modified adaptive hill climbing (MAHC) MPPT method is introduced. It can be treated as an extension of the traditional hill climbing algorithm. The simulation and experimental results show that the proposed MPPT control can avoid tracking deviation and result in improved performance in both dynamic response and steady-state.
676 citations
TL;DR: It is found that the peak power point of a module is significantly decreased due to only the slightest shading of the module, and that this effect is propagated through other nonshaded modules connected in series with the shaded one.
Abstract: This paper looks at the performance of photovoltaic modules in nonideal conditions and proposes topologies to minimize the degradation of performance caused by these conditions. It is found that the peak power point of a module is significantly decreased due to only the slightest shading of the module, and that this effect is propagated through other nonshaded modules connected in series with the shaded one. Based on this result, two topologies for parallel module connections have been outlined. In addition, dc/dc converter technologies, which are necessary to the design, are compared by way of their dynamic models, frequency characteristics, and component cost. Out of this comparison, a recommendation has been made
609 citations
20 Jun 2004
TL;DR: A novel modeling process is proposed to configure a computer simulation model, which is able to demonstrate the cell's output features in terms of environment changes in irradiance and temperature, and is tested to simulate three popular types of photovoltaic panels.
Abstract: The mathematical description of current-voltage characteristics for photovoltaic cells are generally represented by a coupled nonlinear equation, which is difficult to solve by analytical methods. In this paper, a novel modeling process is proposed to configure a computer simulation model, which is able to demonstrate the cell's output features in terms of environment changes in irradiance and temperature. Based on a simplified single-diode model, the parameters are determined in the sense of minimum model error and temperature effect. It is tested to simulate three popular types of photovoltaic panels made of different materials, CIS thin film, multicrystalline silicon, and monocrystalline silicon. The effectiveness of this approach is evaluated through comparison of simulation results to the data provided by product's manufacturer.
450 citations
TL;DR: In this paper, a multiresonant dc-dc converter in a two-stage smart battery charger for neighborhood electric vehicle applications is presented, which eliminates both low and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger.
Abstract: In this paper, resonant tank design procedure and practical design considerations are presented for a high performance LLC multiresonant dc-dc converter in a two-stage smart battery charger for neighborhood electric vehicle applications. The multiresonant converter has been analyzed and its performance characteristics are presented. It eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger. Simulation and experimental results are presented for a prototype unit converting 390 V from the input dc link to an output voltage range of 48-72 V dc at 650 W. The prototype achieves a peak efficiency of 96%.
390 citations
TL;DR: In this article, a bridgeless interleaved power factor correction topology is proposed for level II plug-in hybrid electric vehicle (PHEV) battery charging, which can achieve high efficiency, which is critical for minimizing the charger size and the amount and cost of electricity drawn from the utility.
Abstract: In this paper, a new front end ac-dc bridgeless interleaved power factor correction topology is proposed for level II plug-in hybrid electric vehicle (PHEV) battery charging. The topology can achieve high efficiency, which is critical for minimizing the charger size, PHEV charging time and the amount and cost of electricity drawn from the utility. In addition, a detailed analytical model for this topology is presented, enabling the calculation of the converter power losses and efficiency. Experimental and simulation results are included for a prototype boost converter converting universal ac input voltage (85-265 V) to 400 V dc output at up to 3.4 kW load. The experimental results demonstrate a power factor greater than 0.99 from 750 W to 3.4 kW, THD less than 5% from half load to full load and a peak efficiency of 98.9% at 70 kHz switching frequency, 265 V input and 1.2 kW load.
341 citations
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TL;DR: The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed in this paper, and at least 19 distinct methods have been introduced in the literature, with many variations on implementation.
Abstract: The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.
5,022 citations
TL;DR: In this article, the authors proposed a method of modeling and simulation of photovoltaic arrays by adjusting the curve at three points: open circuit, maximum power, and short circuit.
Abstract: This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I-V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array data sheets, the method finds the best I-V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I-V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulations of PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.
3,811 citations
TL;DR: In this paper, the authors present the current status and implementation of battery chargers, charging power levels, and infrastructure for plug-in electric vehicles and hybrid vehicles and classify them into off-board and on-board types with unidirectional or bidirectional power flow.
Abstract: This paper reviews the current status and implementation of battery chargers, charging power levels, and infrastructure for plug-in electric vehicles and hybrids. Charger systems are categorized into off-board and on-board types with unidirectional or bidirectional power flow. Unidirectional charging limits hardware requirements and simplifies interconnection issues. Bidirectional charging supports battery energy injection back to the grid. Typical on-board chargers restrict power because of weight, space, and cost constraints. They can be integrated with the electric drive to avoid these problems. The availability of charging infrastructure reduces on-board energy storage requirements and costs. On-board charger systems can be conductive or inductive. An off-board charger can be designed for high charging rates and is less constrained by size and weight. Level 1 (convenience), Level 2 (primary), and Level 3 (fast) power levels are discussed. Future aspects such as roadbed charging are presented. Various power level chargers and infrastructure configurations are presented, compared, and evaluated based on amount of power, charging time and location, cost, equipment, and other factors.
2,327 citations
Journal Article•
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TL;DR: In this paper, two major figures in adaptive control provide a wealth of material for researchers, practitioners, and students to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs.
Abstract: This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.
1,814 citations
TL;DR: This paper presents an exhaustive review of three-phase improved power quality AC-DC converters configurations, control strategies, selection of components, comparative factors, recent trends, their suitability, and selection for specific applications.
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.
1,691 citations