NMOS-based integrated modular bypass for use in solar systems (NIMBUS): intelligent bypass for reducing partial shading power loss in solar panel applications

NMOS-based Integrated Modular Bypass for Use in Solar systems (NIMBUS) is designed as a replacement for the traditional bypass diode, used in common solar panels. Because of the series connection between the individual solar cells, the power output of a photovoltaic (PV) panel will drop disproportionally under partial shading. Currently, this is solved by dividing the PV panel into substrings, each with a diode bypass placed in parallel. This allows an alternative current path. However, the diodes still have a significant voltage drop (about 350 mV), and due to the fairly large currents in a panel, the diodes are dissipating power that we would rather see at the output of the panel. The NIMBUS chip, being a low-voltage-drop switch, aims to replace these diodes and, thus, reduce that power loss. NIMBUS is a smart bypass: a completely stand-alone system that detects the failing of one or more cells and activates when necessary. It is designed for a 100-mV voltage drop under a 5-A load current. When two or more NIMBUS chips are placed in parallel, an internal synchronization circuit ensures proper operation to provide for larger load currents. This paper will elaborate on the operation, design and implementation of the NIMBUS chip, as well as on the first measurements

Driving electronics for OLED lighting

This paper proposes the concept of integrating an OLED (foil) and its driving electronics into one module. A complete light system consisting of these modules is the ultimate goal of this work. The main focus in this article is on the design of the driver chip and the circuit implementation. The measurement results confirm that it is possible to control the light output of the different modules

A high-efficiency and compact charge pump with charge recycling scheme and finger boost capacitor

A 16-phase 8-branch charge pump with finger boost capacitor is proposed to increase the power efficiency. Compared with the standard capacitor, the finger capacitor can significantly reduce the parasitic capacitance. The proposed four-stage charge pump with finger capacitor can achieve 14.2 V output voltage from a 3 V power supply. The finger capacitor can increase the power efficiency of the charge pump to 60.5% and save chip area as well

Switch for the optimization of module power by reconfiguration of all strings (SOMBRA) : an insulated integrated switch for a reconfigurable solar panel

The energy yield of a solar panel can be severely impacted by partial shading. Shade caused by nearby static objects can hardly be avoided in installations such as building-applied or building-integrated photovoltaics. Smart reconfigurable photovoltaics (PV) panels are able to change their intra-module configuration to reduce this impact: small substrings can be rewired to be connected in a more optimal configuration. To achieve this, a reconfiguration switch needs to be designed. In this paper a switch for the optimization of module power by reconfiguration of all strings (SOMBRA), a smart switch, is presented. SOMBRA is a fully integrated, low-ohmic switch, designed for currents up to 10 A. It is fully floating up to 50 V, while still being able to communicate with a central unit as an inter-integrated circuit ((IC)-C-2) slave. Two versions were realized, SOMBRA-LV10 for low voltages (LV) and a load current of 10 A, and SOMBRA-HV05 for high voltages (HV) and a load current of 5 A. Measurements proved these devices to be functional, measuring an on-resistance of 1.3 m Omega for SOMBRA-LV10 and 7.3 m Omega for SOMBRA-HV05. This paper will elaborate on the operation, design, and implementation of SOMRBA, as well as the first tests with a small reconfigurable PV module

Over-the-air software updates in the internet of things : an overview of key principles

Due to the fast pace at which IoT is evolving, there is an increasing need to support over-theair software updates for security updates, bug fixes, and software extensions. To this end, multiple over-the-air techniques have been proposed, each covering a specific aspect of the update process, such as (partial) code updates, data dissemination, and security. However, each technique introduces overhead, especially in terms of energy consumption, thereby impacting the operational lifetime of the battery constrained devices. Until now, a comprehensive overview describing the different update steps and quantifying the impact of each step is missing in the scientific literature, making it hard to assess the overall feasibility of an over-the-air update. To remedy this, our article analyzes which parts of an IoT operating system are most updated after device deployment, proposes a step-by-step approach to integrate software updates in IoT solutions, and quantifies the energy cost of each of the involved steps. The results show that besides the obvious dissemination cost, other phases such as security also introduce a significant overhead. For instance, a typical firmware update requires 135.026 mJ, of which the main portions are data dissemination (63.11 percent) and encryption (5.29 percent). However, when modular updates are used instead, the energy cost (e.g., for a MAC update) is reduced to 26.743 mJ (48.69 percent for data dissemination and 26.47 percent for encryption)

Portability, compatibility and reuse of MAC protocols across different IoT radio platforms

To cope with the diversity of Internet of Things (loT) requirements, a large number of Medium Access Control (MAC) protocols have been proposed in scientific literature, many of which are designed for specific application domains. However, for most of these MAC protocols, no multi-platform software implementation is available. In fact, the path from conceptual MAC protocol proposed in theoretical papers, towards an actual working implementation is rife with pitfalls. (i) A first problem is the timing bugs, frequently encountered in MAC implementations. (ii) Furthermore, once implemented, many MAC protocols are strongly optimized for specific hardware, thereby limiting the potential of software reuse or modifications. (iii) Finally, in real-life conditions, the performance of the MAC protocol varies strongly depending on the actual underlying radio chip. As a result, the same MAC protocol implementation acts differently per platform, resulting in unpredictable/asymmetrical behavior when multiple platforms are combined in the same network. This paper describes in detail the challenges related to multi-platform MAC development, and experimentally quantifies how the above issues impact the MAC protocol performance when running MAC protocols on multiple radio chips. Finally, an overall methodology is proposed to avoid the previously mentioned cross-platform compatibility issues. (C) 2018 Elsevier B.V. All rights reserved

Vacuum lamination of a stretchable sensor system in polypropylene

The explosive growth of the so-called Internet-of-Things, where more and more everyday objects are becoming `smart' and connected, demands for reliable integration technologies for electronics in all kinds of materials. If we want these electronics to be as least intrusive as possible, they preferably conform to the shape of the contemplated object. In this article we want to present a technique that allows the integration of a smart sensor system in a thermoplastic material (polypropylene, PP) by vacuum lamination. This laminated stack can then be thermoformed from a flat sheet into the desired 3D shape. The sensor system in question is a sensor bus incorporating three inertial movement sensors. Each sensor is placed on a separate small, thin (200μm) FR4 PCB together with some necessary peripheral components. These smart sensor nodes are then placed on a flexible, stretchable circuit, which is then laminated between two 2mm-thick PP sheets. These sheets can subsequently be heated and thermoformed. In this particular case, the PP was used to create a smart ankle-foot orthosis (AFO). Although long-term reliability needs to be improved, we can show that the discussed technology allows for a successful lamination and thermoforming. This paper will elaborate on the sensor system, stretchable bus system and lamination technique, together with the encountered problems and implemented mitigations. While the current application is the aforementioned AFO, the sensor system can easily be expanded to other types of sensors and the thermoforming process allows for a wide range of possible applications