Battery Management System in Electric Vehicles

Here this document provides the data about the batteries of electric vehicles. It consists of numerous data about various energy storage methods in EVs and how it is different from energy storage of IC-engine vehicles. How electric vehicles will take over ICEngine vehicles due to advancement in battery technology and the shrink in its prices. Various types of batteries are listed in the document with their specifications. Possible future battery technology which will have more or same energy density than current gasoline fuels and also with the significant reduction in battery weights; which will make EVs cheaper than current condition. Some examples are listed showing current battery capacities of various EVs models. Some battery parameters are shown in the document with introduction to BMS (Battery Management System). Then a brief introduction about the charging of these EV batteries and its types displaying variations in charging time in different types of EVs according to their charger type and manufacturers. How DC charging is more time saving method than AC and how smart charging will help to grid in case of peak or grid failure conditions

Efficient Charging System for Hyperloop Application

Conventional transportation methods are a major contributor to the climate crisis and Hyperloop systems are a proposed form of novel transportation that can provide a fast and energyefficient alternative. However, current research in Hyperloop technology has neglected the development of the charging infrastructure to facilitate repeated and high-speed charging cycles that minimize battery degradation. To address this, an efficient charging system for Hyperloop application is presented in this paper. Starting with a pre-existing electric vehicle (EV) charging model in MATLAB Simulink, the design was validated and scaled for the Hyperloop application to support a Lithium Iron Phosphate (LiFePO4) battery pack with parameters of 800V and 185Ah. This model was used to test the performance of the proposed charger and observe battery degradation in a variety of scenarios. Upon testing, the system parameters were tuned to successfully charge the specified battery pack in 42 minutes with the potential to decrease the charge duration by up to four times by using a higher charging current. The design was then scaled down to supply a LiFePO4 battery pack with 6.6V and 2.3Ah, which could be built in hardware to safely test and validate the design. The results of the small-scale prototype model were then compared with the full-scale model results. This yielded the same charge curve characteristics with only a 6% difference in the voltage magnitude, thus validating the scalability of the charging system. Finally, to minimize the effects of battery degradation, a temperature control system was designed to keep the battery pack at its ideal temperature (25°C) and was simulated at extreme temperatures of -30°C and 45°C. The results of the temperature control system showed a 7.2% reduction in battery degradation when compared to a system without a temperature control system

Battery charging system incorporating an equalisation circuit for electric vehicles

Ph.D. ThesisHybrid electric vehicles (HEVs) and electric vehicles (EVs) are gaining in popularity mainly due to the fact that unlike combustion-powered vehicles, they do not pollute with greenhouse gases and toxic particles. Most HEVs and EVs are powered by lithium-ion battery packs which have high power density and longer cycle lives compared to other battery types. Each pack is made out of many battery cells in series connected and due to manufacturing tolerances and chemical processes in individual cells each cell has its own electric characteristics. In order to achieve a balanced voltage across all cells, a battery management system (BMS) must be employed to actively monitor and balance the cells voltage. On-board battery chargers are installed in HEVs/EVs to charge the lithium-ion battery pack from the grid. This charger converts AC grid voltage into a controllable DC output voltage, but it adds weight to the vehicle, reducing the overall efficiency of an HEV/EV and also increasing its cost. The aim of researches in multi-functional power electronics is to design systems which perform several different functions at the same time. These systems promise cost and weight reductions since only one circuit is used to conduct different functions. An example is the electric drive in an HEV/EV. On one hand, it propels the car forward when driving, while on the other hand the battery can be charged via a modified electric motor and inverter topology. Thus, no additional on-board charger is required. This thesis describes a new multi-functional circuit for HEVs/EVs which combines the functions of voltage equalisation with grid charging. Compared to a drive system, the proposed circuit does not rely on an electric motor to charge the battery. Various battery chargers and equalisation circuits are first compared. Then, the design of the proposed circuit is described and simulation results are presented for charging and voltage balancing. An experimental test rig was built and practical results have been captured and compared with simulation results for validation. The advantages and disadvantages of the proposed circuit are discussed at the end of the thesis. Keywords- Multi-functional system, Battery charging, Voltage equalisation, Lithium-ion batter

Design of master and slave modules on battery management system for electric vehicles

Nowadays, electric vehicle usage and the use of LiFePO4 batteries in electric vehicles gradually increase. However, there are important features to be considered to use these batteries safely and efficiently. Incorrect use of these batteries can lead to burning, explosion or shortening of the life of batteries. In this paper, a Battery Management System (BMS) for lithium based batteries is designed that operates more efficiently and communicates with UART between master and slave modules and can communicate via CAN protocol with external devices. Micro controller based control and protection equipment is designed that help to measure and monitor the voltage, temperature and current values of the batteries. They protect the battery cells from the conditions such as over charge, over discharge, high current, high temperature. BMS balances battery cell voltages during charging process with passive cell voltage balancing. In addition to the main controller module in the BMS, slave controller modules have been added to provide high resolution voltage and temperature tracking. A modular BMS has been devised which can be used in groups of batteries of different voltage values thanks to electrically isolated slave control modules

E-transportation: the role of embedded systems in electric energy transfer from grid to vehicle

Electric vehicles (EVs) are a promising solution to reduce the transportation dependency on oil, as well as the environmental concerns. Realization of E-transportation relies on providing electrical energy to the EVs in an effective way. Energy storage system (ESS) technologies, including batteries and ultra-capacitors, have been significantly improved in terms of stored energy and power. Beside technology advancements, a battery management system is necessary to enhance safety, reliability and efficiency of the battery. Moreover, charging infrastructure is crucial to transfer electrical energy from the grid to the EV in an effective and reliable way. Every aspect of E-transportation is permeated by the presence of an intelligent hardware platform, which is embedded in the vehicle components, provided with the proper interfaces to address the communication, control and sensing needs. This embedded system controls the power electronics devices, negotiates with the partners in multi-agent scenarios, and performs fundamental tasks such as power flow control and battery management. The aim of this paper is to give an overview of the open challenges in E-transportation and to show the fundamental role played by embedded systems. The conclusion is that transportation electrification cannot fully be realized without the inclusion of the recent advancements in embedded systems

A smart high-voltage cell detecting and equalizing circuit for LiFePO4 batteries in electric vehicles

A battery management system (BMS) plays an important role in electric vehicles (EVs) in order to achieve a reasonable-lasting lifetime. An equalizing method is essential in order to obtain the best performance. A monitoring system is required to check if any cell voltage is high or low. In this paper, an equalizing and monitoring system for an ultra-light electric vehicle is proposed. The monitoring system detects if one cell is fully charged or all cells are fully charged and the equalizing system tops each cell at the desired voltage. To solve this issue, a light-emitting diode (LED) band gap is used as a voltage reference to inform the user if any cell is at its high voltage. A smart monitoring displays on the liquid crystal display (LCD), if one cell is high or all cells are high. This detection also provides a signal to the microcontroller to turn on/off the charger if all cells are high. Also, a Bluetooth module was designed to command the microcontroller the charger to turn on/off via voice/text message by using a smartphone. Additionally, a new smart monitoring system based on the Bluetooth model (HC05) and mobile app has been made in order to monitor individual cell voltage. A major feature of the system is to draw a very-low current, so that the system does not contribute significantly to the self-discharge of the battery and the circuit does not need sophisticated control. Manufacturers of large electric vehicles may have more intelligent systems that may require a permanent connection to the grid and allow high standby losses, where more state of charge (SOC) may be lost per day. The paper is rather focused on reducing the standby losses, and to activate the equalizer only when charging and/or driving. The experimental results are performed in order to verify the feasibility of the proposed circuit

An Integral Battery Charger with Power Factor Correction for Electric Scooter

This paper presents an integral battery charger for an electric scooter with high voltage batteries and interior-permanent-magnet motor traction drive. The battery charger is derived from the power hardware of the scooter, with the ac motor drive that operates as three-phase boost rectifier with power factor correction capability. The control of the charger is also integrated into the scooter control firmware that is implemented on a fixed-point DSP controller. Current-controlled or voltage-controlled charge modes are actuated according to the requirements of the battery management system, that is embedded into the battery pack. With respect to previous integrated chargers, the ac current is absorbed at unitary power factor with no harmonic distortion. Moreover, no additional filtering is needed since the pulsewidth modulation ripple is minimized by means of phase interleaving. The feasibility of the integral charger with different ac motors (induction motor, surface-mounted phase modulation motor) is also discussed, by means of a general model purposely developed for three-phase ac machines. The effectiveness of the proposed battery charger is experimentally demonstrated on a prototype electric scooter, equipped with two Li-ion battery packs rated 260 V, 20 A