Evaluation of Balancing Circuits Used in Battery System

Evaluation of Balancing Circuits Used in Battery formation life story EPISODE 22.1 INTRODUCTIONMy second cargoner episode describes my find out that is c on the wholeed Evaluation of balancing circumferences apply in electric battery system. This project was completed as a bureau of my minor thesis in the fulfilment of my masters dot program from Swinburne University of Technology, Australia in December 2016. I completed my masters degree in electrical and electronics engineering science. It was completed under the supervision of Prof. Weixing Shen, senior lecturer at the university. And was similarly affirmed by Prof. George Banky.2.2 BACKGROUNDElectric vehicle which operates on battery doesnt operate on a single battery as sufficient energy is not supplied through it. Thus, many batteries that are each connected in series or parallel are required for the generation of required potency and up-to-date for the system to function. The difference in the cadre electromotive force of the stack reduces the string capacity and consequently a system is required that will be able to achieve and maintain the voltage and current that is required by the system along with considering the issue of reliability and performance. For this purpose, a BMS is utilize. Battery Management System (BMS), which gutter oversee the voltage and the current level and muckle similarly charge the battery.2.3The main depend and goal behind implementing this project was to design a 48V battery stack tycoon system that consists of 12 lithium ion battery cells. The monitoring and supervision of each cell operation and voltage level and its charging place can be done with the servicing of LTC3300-1/LTC6803-2 bifacial cell residuer along with the BMS system. It also considers the sentry go concern of the batteries that are used. And the other objective behind implementing this project was to understand LTC330-1/LTC6803-2 bidirectional cell remnant kits performance along with checking its progenys make on QuikEval software and DC590B USB serial control when connected to the calculator.2.4The idea is to balance the voltage supply of the cells so that it provides constant battery voltage to the shelter of the electric vehicle. The overcharging of the battery results in voltage battery degradation and can have consequences like it may catch fire or explosion. Whereas undercharging of the cell or having voltage under the required level may affect the life of the cells. So, I have make use of lithium ion batteries which are then further connected to LTC3300-1/LTC6803-2 bidirectional cell balancer that would assist in achieving the required voltage level of the cell and it can also help in increasing the life of the cell or battery long with providing the supply voltage of EV.2.5The project was completed in a group of two. And I took the opportunity to become the team leader. I root involved with my supervisor in planning the topic and how to start fixing on the project. Based on that I prepared a f miserable chart in which all the major task was separate and assigned among team member along with a deadline so that the final project gets completed in time and there will be time for troubleshooting. later deciding the topic and assigning task, I made myself busy with researching and with lit review of the topic by referring various journal, books, and internet material. The afterward part was designing and implementing the hardware structure along with its software part for its functioning. I had to weekly report to the prof about my project update and took feedback on my project which helped me improve a lot. Weekly meetings with the supervisor was all done through emails or small presentations.2.6 PERSONAL ENGINEERING ACTIVITYI started my project with literature review on cell balancing where cell balancing is a process that involves adjusting the cell voltages to same(p) level i.e. where the battery cells are not over ch arged or over discharged. Also, its internal parameters are the reason for its unbalance like its time of manufacturing, internal resistance etc. It also depends on almost of the external resources like thermal difference between battery cells. The process of battery balancing in lithium ion batteries is an easy process due to its property of charge-discharge expertness. It also provides increased life span and the compensate voltage for its application. After understanding the concepts that were going to be used in my project I started perform research on the components that could be used for my system. It took lot of survey and suggestions were taken from seniors and lecturer about it. and later I finalized the following hardware components that suited best for the project.2.71. Lithium ion (Li-ion) batteries this battery was used due to its high- supply efficiency and has relatively longer battery cycle life which is an strategic feature for my system as the electric vehi cle requires battery than can store more as well as can frequently recharge. Basically, there are two parameters that affect the overall performance of the battery. They are power and the battery diving range.2. LTC3300-1/LTC6803-2 bidirectional cell balancer for cell balancing and monitoring purpose I made use of two ICs that are functioning as bidirectional cell balancer. Active balancing dogma is used by BMS. The two ICs are LTC3300-1, which can balance 6 cells whereas the LTC6803-2 microcontroller IC can support 12 cells when connected to each other in series alliance. The function of LTC3300-1 is to equalize the SoC i.e. state of charge when the battery modules are connected in series manner. It can charge the battery stack rapid and extent the runtime and enhancing the overall performance by cell balancing and charging. Moreover, this IC can balance 6 cells connected to each other in series when it functions as transformer based on bidirectional spry balancing system that has synchronous fly back topology. Looking at the other IC i.e. LTC6803-2 is also a microcontroller IC that can support up-to 12 batteries connected in series connection. It uses antithetical chemical material than the other IC for monitoring the batteries. It gives more accurate results and low error rate, as low as 0.25% of total. It generally operates in three modes measure, shutdown and standby.3. DC590B USB serial controller it is a kind of controller that is specially designed using QuikEval software for display and demonstration of the results and for technologies involving linear family circuits. It is a controller that is based on USB. It is generally isolated or separate from the host computer. So therefore, no external or additional power supply is needed to drive the controller.4. Power supply GPS18500 instrument is one of a kind device which is used in my system as for this project a DC power supply of +5V is required externally to drive the unit. This power supply has many different configurations that include versatile voltage and fixed voltage. It has the feature of supplying 2 different power supply which can work and be used independently. In this device, a slot that gives out fixed supply of +5V DC is provided to the LTC3300-1 bidirectional PCB.2.8After having finalized the hardware components, they were implemented on the evaluation board. The diagram attached shows the circuit and hardware connection for this project. It can be observed that a DC2064A GUI evaluation board, 14 conductor ribbon cables, computer that has QuikEval software installed and USB/serial port cable along with DB590B USB series controller is been used and a power supply of +5V is supplied externally using the GPS18500 device discussed earlier.Various precaution and safety measure was considered while connecting all the different components to the evaluation board. This was done precisely and carefully as any wrong connection made, it can damage the whole circuit ry and the cost of application will increase indirectly. The two ICs LTC3300-1 and LTC6803-2 are soldered or outfit to the evaluation board DC2064A GUI along with the capacitors, MOSFET and transformers. The voltage level and the temperate can be monitored with this circuit board and has the capability to balance the cell voltage. This board also has a special feature of near fault detector that helps to secure the performance of the board in case of any spark or short circuit. 3.7V and 2600mAH assemble lithium ion battery is used in my system. Thus 6 batteries giving a output voltage of 22.8V when connected in series are used on the board as the board can withstand a maximum of 12 batteries for balancing.2.9After successful implementation of the hardware, scrutiny and trouble shooting was performed. For that a QuikEval software was used to monitor the battery stack. To use the software, it had to be configured accordingly for both the microcontroller ICs that were used in the s ystem. After proper implementation, the prove looked as below.From that it can be depicted that the when we press the button called START CONTINUES READ CELL, voltage level can be hold and measured from each battery connected in the battery stack. From performing the test run, I found the cell voltage for each cell was almost 3.7V. But if there is any minor reassign in the voltage level of any cell it can be equalized by transferring cell voltage manually for 5sec and charge the required cell by discharging other cells with high voltage to get an correspondence stage. All the charging/discharging or any error situation status can be seen on the screen as that status will be highlighted.2.10The struggle in implementing this project was getting the expect outcome. It different the actual outcome. It took many efforts, there were issues like the hardware didnt receive any signals from the software. The problem was exculpated by reconnecting few hardware wires. Also, it required ch anging the voltage level of the components by choosing higher level components. After the final configuration, the hardware received the signal and the voltage level of each cells were determined. The later challenge was the important task and the main idea of our project i.e. cell balancing by voltage levels. The output was taken and written down at each time for charging/discharging function and the examine was carried out until the satisfied result was attained. There were times when I didnt get the desired result even after performing the experiment several times. During this phase, my faculty members and supervisors helped me a lot and gave me steps or hints on how I can solve the error.2.11 SUMMARYTo conclude, my project used 3.7V lithium ion battery that has 2600mAH of capacity for active cell balancing technique while making use of two microcontroller ICs configured on evaluation board. The transfer of charging from one cell to another is done using the six lithium ion bat teries that are connected in series on the evaluation board. Along with that the software QuikEval was used to trace the output. The project has an open window in name for expansion for future project work based on this system. This project can be used for self-controlling function to detect faulty or imbalance situation in the system along with capability for temperature measurement unit.Though I could only achieve partial results from my experiment as it varied from expected outcome. But this experiment helped me in many other ways. It taught me to handle complex circuits and outcomes, though I didnt partly achieve what I expected from this but it gave me the strength and knowledge on how to overcome such situations. It was a new learning experience by working in groups and team mates. It involved managing different views and orgasm to one conclusion before implementing the idea. Also, I had the opportunity to apply my previous engineering knowledge into this project.