A low-cost MPPT multiple-input power converter for home applications in isolated areas

The focus of this research is to design and build a low-cost maximum power point tracking (MPPT) multiple-input-single-output power converter system for low power gridisolated applications. The design of this power converter concentrated on searching for a suitable topology that integrates multiple renewable power sources, each with their own MPPT requirements and with the lowest cost of components. With good power conversion efficiency, the converter provides power to a dc load output and is also able to appropriately charge an energy storage battery. In addition to the main functional blocks, all protections required are equipped with the converter, including under voltage lock-out (UVLO), over voltage protection (OVP), cycle-by-cycle current limit, and battery over charge and over discharge prevention. The development and implementation of the converter was divided by different steps. The initial phase searched for, analyzed, and proposed the most suitable topology in terms of power delivery, cost, and feasibility. The non-isolated full-bridge was chosen for the power conversion topology for each channel with its own analogue controller. An interfacing circuit was designed to work with those full-bridge controllers for integrating MPPT control signals, constant output voltage control signals, and constant charging current control signals, from a microcontroller, a single output voltage feedback loop, and a single output current feedback loop, respectively. After a specification of the design had been selected, the detailed design and calculation of circuits was carried out. Simulations were also conducted to confirm the operation of the converter, including the start-up sequences, output load response, battery charging modes, and the transient between operation modes. The converter was then transferred to PCB design with two versions, a 2-layer and 4-layer board. A comparison was made for choosing the appropriate option among the designs regarding board size, cost, and performance. The final physical converter was formed by soldering components on the manufactured 170mm x 130mm 4-layer PCB, and programming of the microprocessor. The final step was the characterisation of the converter with standard power supplies and renewable energy source emulators, in the laboratory environment. Results show that the converter functions as per the design specifications. With the input source of a solar photovoltaic panel, a micro wind/hydro turbine, or both, the converter can work with solely a dc load or with a dc-bus connected battery (where the converter provides a threestage charging profile). The smooth and fast transiting between operation modes of MPPT, constant output voltage, and constant charging current were recorded without any abnormal behavior. The MPPT functions separately with each input source with high accuracy and fast response to the input conditions. Depending on the state of the output, the converter automatically switches to either constant output voltage or constant charging current mode when the total available input power is higher than the output load demand. For each of these operation modes, the converter also achieves a fast response to the input sources voltage and output load variations. With a designed capability of 2 kW maximum total power conversion, the converter is able to work with a wide range of input voltage (from 16 V to 60 V) for both input sources while its nominal output voltage is set at around 27 V for working with a nominal 24 V lead-acid battery. The peak power conversion efficiency of 95.3 % was recorded at 400 W of total input power when the turbine source voltage was 54 V (dc value after the rectifier) and the solar photovoltaic source voltage was 24 V. The operating temperature of the converter appeared to be higher than expected at some components, with a peak of 68.3 oC recorded on the gate driver chips. However, this issue could be mitigated by adding more heat sink components or modifying the design on a new revision. With under $60 USD of total component cost (slightly above$55 for pre-manufactured components and materials, and about $3 for the PCB), the converter is shown to be a low-cost converter regarding its power capability while supporting multiple input sources which may have a wide range of nominal power outputs. This makes the converter more applicable in isolated areas of developing countries

Simulation and optimization of a silicon-polymer bimorph microgripper

This paper presents an electro-thermally bimorph microgripper based on silicon-polymer laterally stacked structures and a method to optimized the fabricated device. The actuated displacement is enhanced due to the polymer constraint effect. Both the thermal expansion and apparent Young’s modulus of the constrained polymer blocks are significantly improved, compared with the no constraint one. The device consists of a serpentine-shape deep silicon structure with a thin film aluminum heater on the top and filling polymer in the trenches among the vertical silicon parts. The fabricated bimorph microgripper can operate in four modes and generates a large motion up to 15 μm. The simulated results are met the fabricated measurements. An optimized structure is proposed for decreasing the working temperature, power consumption but increasing the output displacement. The simulated results are showed that the output displacement is increased up to 550% and temperature profile improved considerably. This electro-thermally silicon-polymer opened and closed microgripper can be used in micro-robotics, micro-assembly, minimally invasive surgery, living cells surgery.

Thu Thiem new urban center Master plan: urban design in the direction of adapting to the natural and cultural environment

The aim of this research is to analyze the Master plan of Thu Thiem new urban center of Ho Chi Minh City, showing the advantages of the project in adaptation to the natural environment and local cultural environment: to inherit and convey the characteristics of historical urban space to the new urban center, to inherit the principle of zoning and functional integration in land use, to maintain harmonious connection with the historic urban center, to arrange a "compact" plan causing no impact to the natural environment, to preserve and embellish the water environment. This research also addresses issues that need to be further researched in the implementation of the Thu Thiem master plan, to ensure the adaptability to the natural and cultural environment of the project which will be successfully applied in practice: to consolidate the characteristics of modernity of new urban architecture, to make the central square diverse and harmonious with human scale, to organize the underground space and height in accordance with the TOD development model, to study the diversity of cultures and local communities in order to plan a unique community

Thu Thiem new urban center Master plan: urban design in the direction of adapting to the natural and cultural environment

The aim of this research is to analyze the Master plan of Thu Thiem new urban center of Ho Chi Minh City, showing the advantages of the project in adaptation to the natural environment and local cultural environment: to inherit and convey the characteristics of historical urban space to the new urban center, to inherit the principle of zoning and functional integration in land use, to maintain harmonious connection with the historic urban center, to arrange a "compact" plan causing no impact to the natural environment, to preserve and embellish the water environment. This research also addresses issues that need to be further researched in the implementation of the Thu Thiem master plan, to ensure the adaptability to the natural and cultural environment of the project which will be successfully applied in practice: to consolidate the characteristics of modernity of new urban architecture, to make the central square diverse and harmonious with human scale, to organize the underground space and height in accordance with the TOD development model, to study the diversity of cultures and local communities in order to plan a unique community

Inter-Frame Based Interpolation for Top–Bottom Packed Frame of 3D Video

The frame-compatible packing for 3D contents is the feasible approach to archive the compatibility with the existing monocular broadcasting system. To perceive better 3D quality, the packed 3D frames are expanded to the full size at the decoder. In this paper, an interpolation technique enhancing and comparing the quality of enlarged halt vertical left and right stereo video in the top–bottom frame-compatible packing is presented. To this end, the appropriate interpolation modes from fourteen available modes for each row segment, which exploit the correlation between left and right stereoscopic as well as current and adjacent frames of individual view, are estimated at the encoder. Based on the information received from the encoder, at the decoder, the interpolation scheme can select the most appropriate available original data to find the missing values of to-be-discarded row segments. The proposed method outperformed than the state-of-the-art interpolation methods in terms of subjective visualization and numerical PSNRs and SSMI about 11%, with an execution time of about 12% comparisons

A Fast, Decentralized, Self-Aligned Carrier Method for Multicellular Converters

International audienceThis paper proposes a fast, decentralized method for self-aligning the carriers of a multiphase/multilevel converter operating on the basis of phase-shifted pulse width modulation or level-shifted pulse width modulation. In the proposed method, each cell of the converter synchronizes and updates simultaneously its own carrier angle or carrier level based on the information shared with its neighboring cell, such as its angle/level, its index number, and the total number of activated cells of the converter. Different from the conventional decentralized method (with basic and modified updating rules), which requires some conditions in terms of cell number and initial carrier angles to start up and operate properly, the proposed method can be applied to the system with any number of cells and does not require special conditions of initial carrier angles. Further, while the conventional method needs an iteration process to adjust the inter-carrier phase-shifts and can be applied only to a multiphase converter which uses phase-shifted pulse width modulation, the proposed method offers an accurate and fast alignment of phases (for phase-shifted pulse width modulation) or levels (for level-shifted pulse width modulation) and thus can be applied to both multiphase and multilevel converter types. The simulations and the experimental results are presented in detail to show the validity and the effectiveness of the proposed methods. Further, thorough simulations on multiphase converters with different number of cells also show that the proposed method is much faster than the conventional method in both configuration and reconfiguration processes, especially in case the system has a large number of cells

Melanotic neuroectodermal tumor of infancy

Introduction: Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, rapidly growing pigmented neoplasm of neural crest origin generally arising in infants during the first year of life. Case: We report a 15-month old male who presented with a 2-month history of a rapidly growing mass in the anterior. A biopsy showed melanotic neuroectodermal tumor, and complete resection with negative margins was subsequently achieved. The patient is in remission at 11 months from surgery. Conclusion: Due to its rapid growth potential and locally destructive behaviour, early diagnosis is extremely important to limit local expansion. The treatment of choice for melanotic neuroectodermal tumor of infancy (MNTI) is surgical excision. Keywords: Melanotic neuroectodermal tumor, Infanc