The intent of this project with Powerco was to identify the cause of premature battery failure and suggest improvements to the Remote Area Power System (RAPS), which is managed by Powerco subsidiary Basepower. An evaluation matrix was used to analyse the most beneficial solution that can be implemented in the RAPS unit. The issues that have caused the early failure for the RAPS have been determined and improvements to the system are suggested. These have been provided to the Powerco Research and Development team for consideration.

This thesis describes the development of a simplified model of a battery energy storage. The battery energy storage is part of the ABB energy storage system DynaPeaQ®. The model has been built to be run in RTDS, a real time digital simulator. Batteries can be represented by equivalent electric circuits, built up of e.g voltage sources and resistances. The magnitude of the components in an equivalent circuit varies with a number of parameters, e.g. state of charge of the battery and current flow through the battery. In order to get a model of how the resistive behaviour of the batteries is influenced by various parameters, a number of simulations have been run on a Matlab/Simulink model provided by the battery manufacturer. This model is implemented as a black box with certain inputs and outputs, and simulates the battery behaviour. From the simulation results a set of equations have been derived, which approximately give the battery resistance under different operational conditions. The equations have been integrated in the RTDS model, together with a number of controls to calculate e.g. state of charge of the batteries and battery temperature. Results from the RTDS model have been compared with results from the Simulink model. The results coincide reasonably well for the conditions tested. However, further testing is needed to ensure that the RTDS model produces results similar enough to the ones from the Simulink model, over the entire operational range.

Abstract In 1999, the Electrical and Computer Engineering Department at the University of Canterbury started building their third electric vehicle (EV3) based on a TOYOTA MR2 with the goal of building a higher performance vehicle to match present combustion engined vehicles. The car is powered by 26 12volt sealed lead-acid batteries connected in series to achieve a nominal 312V DC source. A battery voltage equaliser is a device that draws energy from a higher charged battery, then discharges into a lower charged battery. The need for a voltage equaliser is principally due to the differences in cell chemistry, temperature gradients along the battery string and the ages of the batteries. During the charging or discharging process, some batteries reach their nominal voltage or reach deep discharge states before the others. Then if the charger keeps charging the batteries or the load keeps drawing energy from these batteries, it results in damage to the batteries. Therefore maintaining the charge level on each battery becomes important. In addition, it also improves the battery life and vehicle travelling range. This thesis details the analysis of three different types of battery equaliser, which are based on a 24W buck-boost converter, 192W buck-boost converter and 192W flyback converter. In this design, all converters are designed to work under current mode control with average of 2A. To make each converter install without significant effect on the performance and the cost, each converter is also built with the goals of being small, lightweight, cost effective, flexible for mounting, maintenance free and highly efficient. At the end, the prototype battery equalisation converters were designed, constructed and tested, and the efficiencies from each converter are measured around 90 ~ 92%. The experimental results show two banks of series connected batteries can be successfully equalised by the designed equaliser. This thesis covers the design, simulation and the construction procedures of this battery equaliser system, and also details on some considerations and possible future improvement that were found during the experimental test.

Thesis (doctoral)--Universiteit te Amsterdam, 1892. / Errata slip inserted. Includes bibliographical references.

No description available.

The feasibility of converting an existing internal combustion powered general aviation aircraft to battery electric propulsion was studied. The theoretical performance of various types of airframes with battery electric propulsion systems was compared to determine which type of airframe would be best suited for conversion. It was found that battery electric propulsion is best used in aircraft intended for slow speed, efficient flight and carrying limited payload which is a mission typically flown in motor gliders. A reference motor glider was selected and a conceptual power system packaging design study was performed. The study determined that a critical component of the power system packaging design was the technical feasibility of packaging the batteries inside of the wing structure. This was driven by center of gravity restrictions. Technical concerns related to a battery-in-wing design were investigated, included wing aeroelastic performance, wing stiffness and wing strength. The results showed that aeroelastic flutter was not a driving design criteria for the reference airframe used as the physical size of the battery did not allow for them to be packaged in wing locations that detrimentally affected flutter performance. The battery packaging layout was instead driven by access for battery maintenance, battery safety and the battery thermal management system. Overall weight change from packaging the batteries in the wing compared to the fuselage was found to be negligible. The resulting aircraft conceptual design indicated a powered flight range with reserves of over 200 miles and a powered flight endurance of greater than 3 hours with 2 persons onboard.

Renewable energy integration will become a significant issue as renewable penetration levels increase, and will require new generation support infrastructure; Energy storage provides one solution to this issue. Specifically, battery technologies offer a wide range of energy and power output abilities, making them ideal for a variety of integration applications. Distributed energy storage on distribution grids may be required in many areas of Canada where renewables will be installed. Peak shaving using distributed small (residential) energy storage can provide a reduction in peak loads and help renewable energy integration. To this end, a peak shaving model was developed for typical houses in several regions in Canada which provided sizing and performance results. An experimental battery bank and cycling apparatus was designed and constructed using these sizing results. This battery bank and cycling apparatus was then used to calibrate and validate a lithium iron phosphate battery energy storage system model.

The field of energy storage has improved drastically within the last two decades. Batteries of various chemistries have been relied on to provide energy for numerous portable electronic devices. Lithium-ion cells, when compared to other chemistries have been known to provide outstanding energy-to-weight ratios and exhibit low self-discharge when not in use [1]. The aforementioned benefits in conjunction with decreasing costs have made lithium-ion cells an exceptional choice for use in electrical vehicles (EVs). Battery Management Systems (BMS) in EVs are responsible for providing estimates for values that are indicative of the battery pack’s present operating condition. The current operating condition could be described by State of Charge, power fade, capacity fade and various other parameters [2]. Importantly, it is essential for the estimation technique to adjust to fluctuating cell characteristics as the cell ages, in pursuance of having available accurate estimates for the life time of the pack. In order for the estimation technique to properly estimate the desired quantities, a mathematical model capable of capturing cell dynamics is desired. There are various proposed methods recommended for mathematically modeling a cell, namely equivalent Circuit modeling, electro-chemical modeling and impedance spectroscopy. Consequently, in order to ensure mathematical models are accurate and further to have the ability to compare the proposed models, it is essential to have available data gathered from a given cell at specific operating conditions. This Master’s thesis outlines the development of a lithium-ion cell tester that is capable of controlling, monitoring and recording parameters such as current, voltage and temperature. The Dual capability of obtaining data from standardized cell tests as well as high frequency cell tests is fascinating and intriguing. As this capability holds the possibility of reducing cost otherwise spent on man hours and equipment which are both paramount in any industrially automated process. / Thesis / Master of Applied Science (MASc)

With increasing research on lithium batteries, the technology of electric vehicles equipped with lithium battery packs as the main energy storage system has become more and more mature, and the design and testing of lithium ion battery packs are becoming extremely important. As the battery system becomes more complex, it is necessary to optimize its structural design and to monitor its dynamic performance accurately. This research considers two related topics. The first is the design of a battery submodule made up of cylindrical lithium cells. The objective of this design is to improve its energy density and optimize the heat dissipation performance according to the installation position and space constraints in Ford Focus EV 2013, and, produce a submodule prototype based on this design; The second objective is to derive and verify an equivalent circuit model for a prismatic lithium battery cell of high energy capacity based on experimental results. In terms of mechanical structure, the basic structure of a battery pack is determined by the desired performance as well as cell characteristics. In this research, the Samsung 35E 18650 cylindrical cells are chosen. 20 battery cells are connected in parallel to form a battery submodule, and 13 battery submodules are connected in series to form a battery pack. The battery pack design process mainly includes positioning and connection of battery cells, heat dissipation mechanism, cabling and inside the pack. The above considerations were applied to prototype battery submodule with an energy density of 216.87 Wh/kg. Some key considerations in the design of the battery pack include checking the conductivity and the welding connection. Chemistry of lithium-ion batteries are constantly evolving with industrial demands which call for higher energy storage capacity. Therefore, this research selected a new high-capacity prismatic cell to establish an equivalent circuit model using characterization and experiments, followed by verification. A 280 Ah Lithium Iron Phosphate (LFP) prismatic battery cell was selected and characterized by testing under various operating conditions for validation, the Urban Dynamometer Driving Schedule (UDDS) was used. / Thesis / Master of Applied Science (MASc) / This thesis introduces how to design a battery pack using cylindrical battery cells, also shows how to conduct characterization tests and build a equivalent circuit battery model.

Along with higher data rates and application-enriched user terminals, LTE has even higher requirements to conserve the battery power in mobile devices compared to the WCDMA terminals. In LTE, Discontinuous Reception (DRX) has been introduced as one of the key solutions to conserve battery power in mobile terminal. It is very meaningful to investigate the possible impact of DRX on power consumption and also the VoIP performance. This study evaluates several different parameter settings for DRX, and tries to find a reasonable trade-off between VoIP performance and battery life. This study report proposes DRX parameter setting to achieve maximum possible power saving with minimum VoIP degradation. Based on the assumed power saving model and simulation scenario presented in chapter 4 and chapter 5 of this report respectively, the proposed parameter settings can achieve up to ~60% of the terminal power saving. Furthermore, it is concluded that longer DRX cycles are not suitable for VoIP traffic since they introduces longer delays and degrades the VoIP performance particularly in downlink. / This study has evaluated different DRX parameter settings for VoIP traffic both in uplink and downlink and found out different gains in terms of power saving and network performance. It is shown that key parameters include On-duration Timer, Inactivity Timer and length of DRX cycle. These three parameters have major impact on both VoIP and power saving. Different combinations of these parameters show different results. DRX affects downlink and uplink in a different manner. In the downlink, a user cannot be scheduled and thus receive any DL data during the period of inactivity. Downlink assignments can only be sent when receiving UE is awake. This is one reason that length of DRX cycle and length of On-duration period is more important parameters in downlink. It is found out that increasing the length of DRX cycle, keeping relatively constant average awake time of terminal, introduces larger delays in downlink and thus degrades the performance. On the other hand, uplink is affected by DRX only when there is fragmentation. In uplink, whenever a user has available data it can a scheduling request, which is independent of DRX state and can be sent even if UE is sleeping, and thus can get UL scheduling grant. However, if the grant is fragmented, UE might not always be able to receive remaining fragments due to DRX state. That is why Inactivity Timer plays a more important role in UL. If poor radio conditions are expected, it is important to have larger Inactivity Timer period. From the power saving point of view, the length of On-duration Timer and Inactivity Timer should be chosen as smaller as possible. However, these parameters should not be reduced below a certain threshold. For example reducing On-duration Timer below 2ms shows a major degradation in VoIP performance while not showing a comparable gain in receiver power. This study has proposed a DRX parameter setting to achieve maximum power saving with minimum VoIP degradation. Based on the assumed power saving model and the simulation settings presented in chapter 4 and chapter 5 of this report respectively, the proposed DRX settings show that ~60% of total power can be saved while keeping the VoIP capacity loss <= 12%. / This thesis is about battery saving in LTE