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An overview of BMS functions 

An overview of BMS functions 

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Article
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Increased concerns over limited sources of energy as well as the environmental impact of petroleum based transportation infrastructure have led to an ever increasing interest in electric transportation infrastructure. Thus, electric vehicle (EV), hybrid electric vehicle (HEV), and plug-in hybrid electric vehicle (PHEV) have received a great deal of...

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... the last two decades, there has been an ever-growing trend toward find- ing a reliable alternative and less polluting source of power for automotive engines. Amongst all the proposed and practiced technologies, batteries, and more particularly, Li-ion batteries, have gained the most attraction in auto, space and marines industries thanks to their unique characteristics. High energy density, no memory effect, and low self-discharge rate have made Li-ion batteries a promising source of energy storage. Despite the consensus about their benefits, there have been many challenges along the way to battery development. Improving the energy density, power ca- pability, monitoring and safety aspects of the lithium ion batteries are all challenging problems that researchers are grappling with. As a result, advancement of electric vehicles is highly dependent on development of battery technology and advanced battery management system (BMS) where all activities related to monitoring, safety, efficiency and control of battery are looked after. BMS has actually been an active area of research in the last decade from control and power electronics perspectives [1–4]. This chapter attempts to present some of the main task and functions of an advanced BMS from a control system perspective. The current trends and existing challenges and issues are explored and the future promising areas of research are introduced. Development of an advanced BMS would also draw upon power electronics and communication areas which are beyond the scope of this review. The remainder of this Chapter is organized as follows. Section 2 presents the principles of battery management systems. Section 3 reviews the current modeling approaches to Li-ion battery, their advantages and disadvantages. Section 4 discusses battery estimation techniques, unresolved issues and challenges. The cell balancing problem is explored in section 5. Section 6 summarizes the current practice and future areas of research in thermal management design of BMS. Finally, section 7 provides a brief summary of the paper and highlights the main challenges for design of an advanced integrated BMS. BMS can be characterized as the brain for the battery system. It consists of electrical circuits and embedded algorithms to safely and efficiently operate battery system according to the demands of other vehicle components. The BMS tasks can generally be classified under two modules: “Monitoring” and “Control”. Figure 1 shows the schematic of a typical BMS and some of its basic functions. In the following some of the main features and function requirements of BMS are reviewed. Monitoring module cover all the functions that are required to monitor the battery system’s state of health and charge, and includes measurement or estimation of certain important parameters. The Monitoring module may also exchange information to the user or Control module. Some of the important functions of the Monitoring module are: 1. Measurement (Data Acquisition): This includes measurement of physical parameters such as current, voltage of the battery cells, as well as temperature distribution inside and outside of the battery pack. This information forms the basis for other tasks within the BMS. Measurement of other parameters of the battery such as impedance, etc would also be highly desirable from control point of view. However, this is normally not possible during the normal operation of the battery given the current technology. Hence, certain other parameters of the battery are usually estimated. 2. Estimation: The state of the battery is normally assessed through three indicators which are its state of charge (SoC), state of health (SoH), and state of life (SoL). These parameters are not directly measurable and thus need estimation schemes to be inferred based on the available information from the battery. Depending on the adopted estimation method, some other parameters of the battery might also be ...

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... They however remain a costly and safety critical subsystem in many areas that they are used in. As a result, reliability, safety, and efficient operation of Li-ion batteries in high power applications, such as in electrified vehicles, and challenging problems such as modeling, state estimation, monitoring, diagnostics, and pyrognostics capabilities are critical areas for research [1][2][3][4][5][6][7][8]. ...
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