Battery Modeling

The use of mobile devices is often limited by the capacity of the employed batteries. The battery lifetime determines how long one can use a device. Battery modeling can help to predict, and possibly extend this lifetime. Many different battery models have been developed over the years. However, with these models one can only compute lifetimes for specific discharge profiles, and not for workloads in general. In this paper, we give an overview of the different battery models that are available, and evaluate these models in their suitability to combine them with a workload model to create a more powerful battery model. \u

RF Energy Harvesting System and Circuits for Charging of Wireless Devices Using Spectrum Sensing

Recently, lots of works have been done on the optimal power management of wireless devices. This leads to the main idea of ambient energy harvesting. Among various energy harvesting approaches, one is to use radio waves existing in the ambient environment for battery charging, called RF energy harvesting. In this chapter, in order to improve the RF energy harvesting performance, we utilize spectrum sensing to allow the wireless devices to select the frequency band with maximum power that exceeds a predefined threshold to charge the device (this power threshold can be determined according to battery type and its required charging power) and the device can use this power for battery charging. Also, a novel voltage multiplier circuit is proposed. By means of simulations and experimental tests, it can be seen that after detection of our desired 1 mW RF signal, system output power is about 532μ W and 450μ W in simulation and practical situations respectively

Genetic Algorithm Based Charge Optimization of Lithium-Ion Batteries in Small Satellites

Small spacecraft that are powered by solar energy have limitations because of the size of their solar panels. With the limitations on the solar panel size, it is generally hard to comply with the demands from all the satellite subsystems, payloads and batteries at the same time. To overcome these problems we have developed and adopted a power management optimization scheme that runs in real time in the satellite. The proposed power management scheme primarily involves scheduling of loads (various subsystem operations, payload experimentation, battery charging, etc.) so that power utilization and thereby the charge of the batteries is at its optimum. We have developed a genetic algorithm based schedule optimizer and propose an FPGA based fitness evaluation function for it

Programmable logic devices in sensor networks: a survey

This paper presents a survey about the use of reconfigurable hardware technologies in sensor networks, considering proposals published in two of the leading conferences of Programmable Logic Devices: FPL and SPL. These proposals cover different applications such as wireless communications, different networks topics and sensors. Some of the papers considered in this survey are directly related with WSN, such as reconfigurable nodes or lowpower hardware platforms intended for sensor networks. Other papers are not directly related to WSN, but they present results and concepts that may be of interest in the field of the WSNs.Sociedad Argentina de Informática e Investigación Operativ

Battery/Supercapacitors Combination in Uninterruptible Power Supply (UPS)

International audienceThis study presents a study of the reduction in battery stresses by using supercapacitors (SCs) in a 500-kVA rated UPS. We aim at investigating the optimal supercapacitors-battery combination versus the SCs cost. This investigation is threefold; first, supercapacitors and battery models developed using MATLAB/Simulink are presented and validated. Second, the architecture and the simulation of the designed system that combines the SCs and the battery are shown. The supercapacitors are used as high-power storage devices to smooth the peak power applied to the battery during backup time and to deliver full power during short grid outages. By charging the SCs through the battery at a suitable rate, all impulse power demands would be satisfied by the supercapacitors. Third, extensive simulations are carried out to determine the gain in battery RMS current, the gain in energy losses, the energy efficiency and the elimination rate of surge load power. These four performance parameters are determined by simulation and then analyzed. The influence of the SCs recharge on the performance indicators is highlighted. A thorough analysis involving optimal study proposes to draw the optimal SCs number and filter constant from the variation of the aforementioned parameters versus the cost of the SCs

Rechargeable battery modeling and lifetime optimization

Battery lifetime is one of the most important design considerations in rechargeable battery operated devices. Understanding the battery nonlinear properties is essential for appropriate battery modeling. Optimizing the battery lifetime depends greatly on the discharge current profile. Changing the profile shape can be done through averaging techniques, scheduling techniques, introducing recovery periods, etc. This work investigates the different techniques that can be used to enhance the battery lifetime. It is shown that 15-60% of lifetime savings can be achieved through using average current profile instead of variable current profile. This work also provides a comparison between different configuration techniques for multi-cell systems. Also, a new hybrid battery model is introduced which combines the battery electric circuit characteristics together with the nonlinear battery properties

Design and Simulation of a DC Electric Vehicle Charging Station Interconnected with a MVDC Network

Due to a rapidly aging electric transmission and distribution infrastructure, an increased demand for energy, an increased awareness of climate change and greenhouse gas pollution, and an increased cost of fuel there is a need to produce and deliver energy more efficiently. This thesis attempts to provide a solution to these constraints through advancements in DC power architectures. Medium Voltage Direct Current (MVDC) infrastructure serves as a platform for the interconnection of renewable electric power generation, including wind and solar. Abundant loads such as industrial facilities, data centers, commercial office buildings, industrial parks, and electric vehicle charging stations (EVCS) can also be powered using MVDC technology. MVDC networks are expected to improve efficiency, through reductions in power electronic conversion steps and by serving as an additional layer between the transmission and distribution level voltage for which generation sources and loads could directly interface with smaller rated power conversion equipment. This thesis provides an introduction to battery energy storage system technology, and primarily investigates an EVCS powered via a MVDC bus. A bidirectional DC-DC converter with appropriate controls serves as the interface between the EVCS and the MVDC bus. Two scenarios are investigated for testing and comparing EVCS operation: 1) EVCS power supplied by the interconnected MVDC model and 2) EVCS power supplied by an equivalent voltage source. The ability of the battery charger (synchronous buck converter) to isolate faults in next generation DC power systems is explored. Each of the investigated components is modeled and simulated utilizing the PSCAD simulation environment then analytically validated