Battery Management System and its Applications
Description
Enables readers to understand basic concepts, design, and implementation of battery management systems
Battery Management System and its Applications is an all-in-one guide to basic concepts, design, and applications of battery management systems (BMS), featuring industrially relevant case studies with detailed analysis, and providing clear, concise descriptions of performance testing, battery modeling, functions, and topologies of BMS.
In Battery Management System and its Applications, readers can expect to find information on:
* Core and basic concepts of BMS, to help readers establish a foundation of relevant knowledge before more advanced concepts are introduced
* Performance testing and battery modeling, to help readers fully understand Lithium-ion batteries
* Basic functions and topologies of BMS, with the aim of guiding readers to design simple BMS themselves
* Some advanced functions of BMS, drawing from the research achievements of the authors, who have significant experience in cross-industry research
Featuring detailed case studies and industrial applications, Battery Management System and its Applications is a must-have resource for researchers and professionals working in energy technologies and power electronics, along with advanced undergraduate/postgraduate students majoring in vehicle engineering, power electronics, and automatic control.
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Persons
Xiaojun Tan, Sun Yat-sen University, China, is a Professor and leads the Research Center of New Energy Vehicles at the School of Intelligent Systems Engineering, Sun Yat-sen University. He has nearly two decades' research experience in battery modeling, testing and diagnoses, and has spearheaded many industry partnerships.
Andrea Vezzini, Bern University of Applied Sciences, Switzerland is a Professor with more than two decades' experience in battery systems research and development. He leads the Energy Storage Research Centre (ESReC) at Bern University of Applied Sciences and has been involved through several spin-offs in the product development of customized battery system solutions for the industrial and automotive market.
Yuqian Fan, received his PhD. in Intelligent Transportation Engineering from Sun Yat-sen University, China. His research interests include intelligent control and optimization design for power battery systems, battery thermal management and thermal safety, and battery state of health prediction.
Neeta Khare, is a Director with Iveco Group. Dr. Khare acquired her doctoral degree in Intelligent Battery Monitoring from Banasthali University, India. Her core expertise is in aging algorithms of battery/ cell using AI and adaptive algorithms, Battery Pack, Battery Management System (BMS) development, and more.
You Xu, is an Associate Professor at Guangdong Polytechnic Normal University, China, where he has been engaged in power battery system, precision reverse equipment. Dr. You received his PhD. from Sun Yat-sen University. He has authored over 20 scientific publications, and his research interests include battery management for electrical vehicles.
Liangliang Wei, is an Associate Professor in Control Science and Engineering at Sun Yat-Sen University, China. Dr. Wei has authored over 20 scientific publications and received his PhD. in Electrical Engineering from the Wuhan University, China.
Content
Preface xiii
About the Authors xv
Part I Introduction 1
1 Why Does a Battery Need a BMS? 3
1.1 General Introduction to a BMS 3
1.2 Example of a BMS in a Real System 5
1.3 System Failures Due to the Absence of a BMS 7
2 General Requirements (Functions and Features) 11
2.1 Basic Functions of a BMS 11
2.2 Topological Structure of a BMS 16
3 General Procedure of the BMS Design 19
3.1 Universal Battery Management System and Customized Battery Management System 19
3.2 General Development Flow of the Power Battery Management System 21
Part II Li-Ion Batteries 27
4 Introduction to Li-Ion Batteries 29
4.1 Components of Li-Ion Batteries: Electrodes, Electrolytes, Separators, and Cell Packing 29
4.2 Li-Ion Electrode Manufacturing 31
4.3 Cell Assembly in an Li-Ion Battery 32
4.4 Safety and Cost Prediction 33
5 Schemes of Battery Testing 37
5.1 Battery Tests for BMS Development 37
5.2 Capacity and the Charge and Discharge Rate Test 41
5.3 Discharge Rate Characteristic Test 44
5.4 Charge and Discharge Equilibrium Potential Curves and Equivalent Internal Resistance Tests 46
5.5 Battery Cycle Test 49
5.6 Phased Evaluation of the Cycle Process 58
6 Test Results and Analysis 67
6.1 Characteristic Test Results and Their Analysis 67
6.2 Degradation Test and Analysis 80
7 Battery Modeling 101
7.1 Battery Modeling for BMS 101
7.2 Common Battery Models and Their Deficiencies 102
7.3 External Characteristics of the Li-Ion Power Battery and Their Analysis 105
7.4 A Power Battery Model Based on a Three-Order RC Network 110
7.5 Model Parameterization and Its Online Identification 117
7.6 Battery Cell Simulation Model 124
Part III Functions of BMS 133
8 Battery Monitoring 135
8.1 Discussion on Real Time and Synchronization 135
8.2 Battery Voltage Monitoring 139
8.3 Battery Current Monitoring 145
8.4 Temperature Monitoring 149
9 SoC Estimation of a Battery 153
9.1 Different Understandings of the SoC Definition 153
9.2 Classical Estimation Methods 158
9.3 Difficulty in an SoC Estimation 162
9.4 Actual Problems to Be Considered During an SoC Estimation 166
9.5 Estimation Method Based on the Battery Model and the Extended Kalman Filter 169
9.6 Error Spectrum of the SoC Estimation Based on the EKF 177
10 Charge Control 193
10.1 Introduction 193
10.2 Charging Power Categories 196
10.3 Charge Control Methods 198
10.4 Effect of Charge Control on Battery Performance 203
10.5 Charging Circuits 204
10.6 Infrastructure Development and Challenges 209
10.7 Isolation and Safety Requirement for EC Chargers 211
11 Balancing/Balancing Control 213
11.1 Balancing Control Management and Its Significance 213
11.2 Classification of Balancing Control Management 218
11.3 Review and Analysis of Active Balancing Technologies 221
11.4 Balancing Strategy Study 226
11.5 Two Active Balancing Control Strategies 234
11.6 Evaluation and Comparison of Balancing Control Strategies 245
12 State of Health (SoH) Estimation of a Battery 257
12.1 Definition and Indices/Parameters of SoH 257
12.2 Modeling of Battery Degradation (Aging) and SoH Estimation 265
12.3 Battery Degradation Diagnosis for EVs 278
13 Communication Interface for BMS 291
13.1 BMS Communication Bus and Protocols 293
13.2 Higher-Layer Communication Protocols 298
13.3 A Case Study: Universal CiA EnergyBus for a Low-Emission Vehicle (LEV) 299
14 Battery Lifecycle Information Management 301
14.1 Data Type of Power Battery 301
14.2 Vehicle Instrument Data Display 302
14.3 Battery Data Transmission Mode 306
14.4 Information Concerning a Full-Power Battery Lifecycle 311
14.5 Storage and Analysis of Historical Information of a Battery 316
14.6 Battery Detection System Based on a Mobile Terminal 320
Part IV Case Studies 327
15 BMS for an E-Bike 329
15.1 Balancing 329
15.2 Battery Pack Design for an E-Bike 331
15.3 Methodology 333
15.4 Active Balancing Solutions 337
15.5 Test Results 341
15.6 Possibility with Active Balancing 349
15.7 Results and Evaluation 349
16 BMS for a Fork-Lift 353
16.1 Lithium-Iron-Phosphate Batteries for Fork-Lifts 353
16.2 Battery Management Systems for Fork-Lifts 355
16.3 The LIONIC Battery System for Truck Applications 356
16.4 Application 357
16.5 The Usable Energy Li-Ion Traction Batteries 359
17 BMS for a Minibus 363
17.1 Internal Resistance Analysis of a Power Battery System and Discharging Strategy Research of Vehicles 361
17.2 Consistency Evaluation Research of a Power Battery System 377
17.3 Safety Management and Protection of a Power Battery System 386
Index 389
1
Why Does a Battery Need a BMS?
1.1 General Introduction to a BMS
1.1.1 Why a Battery Needs a BMS
A battery management system (BMS) is an essential part of any energy storage system. It controls battery charging and discharging, manages optimum operating conditions, governs the safety limits, runs the battery charge and health algorithms, monitors battery parameters, and communicates with other associated devices [1, 2]. A BMS or similar monitoring and control system is strongly recommended for other electrical energy systems, such as a fuel cell, supercapacitor, superbat capacitor, or other hybrid combinations of electrical energy storage systems. A BMS allows the system to be efficient and to use an application for stored energy up to the safe operating limit [3]. It makes energy storage cost effective for short-term applications such as consumer electronics. With an efficient control over optimum charge and discharge ranges, the BMS adequately extends the life of energy storage. The increased life makes the energy storage economically viable for long-term applications such as grid, automotive, and stationary applications [4].
1.1.2 What Is a BMS?
A BMS is a control system that ensures optimum use of the battery energy in powering any portable or non-portable system. This is achieved by monitoring and controlling the battery's charging and discharging processes along with careful control over the surrounding environment. The BMS becomes essential in all storage systems to prevent the risk of damaging the battery by misuse. The features of a BMS design should include:
- Charge control
- Battery capacity and efficiency calculations
- Remaining run-time information
- Cycle counting
- Battery life prognosis
- Thermal management
- Prediction of battery failure
- Safety and alarm indications for over the limit usage
An effective BMS can protect the battery from damage, ensure safety, predict battery life, and maintain the battery operation in order to keep efficiency high.
A general block diagram of a BMS is shown in Figure 1.1. The battery-charger charges the battery from the mains. A protection integrated circuit (IC) connected to the battery indicates the unsafe condition of the battery. A protection IC specifically deals with the over/under-voltage protection, over current protection, imbalance of cells, and thermal runaway. In addition, protection circuits also include a blocking diode, each of which is outfitted with a series string that prevents parallel strings from discharging through a battery with an unforeseen short circuit [5]. Researchers, such as Kim et al. [6], have also proposed more robust circuits capable of mitigating the electrical impacts of a single cell failure. Manufacturers of large battery systems typically integrate a proprietary control system as well, in order to control issues such as cell balance, cell temperature, and an estimation of the battery life.
Figure 1.1 Block diagram of a battery management system.
The battery state indicates the current state and future prediction of the battery by using the State of Charge (SoC) and State of Health (SoH). The processor runs the battery management algorithms that compute the SoC, SoH, and property parameters [7]. The subsequent parts in the book will discuss prognostic and diagnostic approaches for determination of the SoC and SoH. Finally, to establish communication between the BMS and other devices, most commonly used interfaces are I2C, Modbus, and CAN ports and protocols.
1.1.3 Why a BMS Is Required in Any Energy Storage System
The demand for an energy storage system is increasing day by day with exponential growth in the area of consumer electronics, portable devices, and e-mobility. In addition, a budding urge for clean energy usage in order to address the challenge of reducing carbon footprints makes energy storage more popular than other stationary applications. At present, stationary applications, such as a grid-connected energy storage, are aggressively being tested around the world. Grid-connected electrical energy storage is a potential candidate for load shifting, PV smoothing, stabilizing the grid, etc. The most popular solution for electric energy storage is a battery pack due to its high energy density, long life, and cost-effective features. However, challenges lie with its optimum performance and safety. The requirement for a BMS controller with energy storage is quite obvious when considering the increasing challenge regarding safety and optimum utilization together with high efficiency. A BMS allows energy storage to function within the safety limits and provides high-performance capabilities.
1.1.4 How a BMS Makes a Storage System Efficient, Safe, and Dependable
An important aspect of BMS functions is to control the battery charging and usage within safe limits. A BMS recommends relevant parameters to the battery charger and commands it to use the most effective charging algorithm. A charging algorithm helps to reduce the charging time, offers a long battery life, and maintains high efficiency, while keeping the operation within given safety limits of voltages, temperature, current, and SoC. The BMS monitors real-time electrical parameters such as terminal voltage, charging and discharging current, temperature, impedance, and number of cycles [8]. Further, it calculates compensation factors, estimates the SoC and SoH, and determines other performance characteristic parameters such as energy efficiency, capacity, and remaining life time. The SoC and SoH are the most critical parameters for maintaining the operation under safe conditions [9, 10]. Monitoring battery health is one of the prime factors affecting the system reliability.
A BMS helps energy storage in the following three ways:
- Increases efficiency by
- Compensating cut-off voltage with temperature variations, C-rate charge and discharge, and aging.
- Selecting appropriate charging current to maintain the current density limit at the electrode surfaces.
- Controlling and compensating the SoC range for charging and discharging over the operating range in order to maintain coulombic efficiency.
- Keeping all cell voltage and SoC balanced to increase its operating range.
- Thermal controlling the pack in order to maintain the optimum temperature range.
- Increases battery life time by
- Saving the battery from abuses of over-charging. Over-charging causes heating and out-gassing that reduces the life of the battery.
- Preventing deep discharging by limiting the discharge at the end of the discharge cut-off voltage. Metal plating is a major cause of shortening the battery age when operating below the end of discharge cut-off voltage.
- Maintaining current density to prevent electrode surfaces from damage.
- Keeping the SoC within the operating range that provides a balance between capacities in and out at various operating conditions.
- Cell balancing prevents under-charging of good cells and over-charging of weak cells, which increase the overall age of the pack.
- Provides safety and reliability by
- Maintaining and controlling operations within the safety limits.
- Indicating safety alarms for events beyond the operating condition.
- Shutting down the operation during a critical safety threat.
- Employing a thermal controlling system to prevent any thermal runaway conditions
- Giving an indication of the remaining battery life and thus facilitating timely action taken proactively in alarming conditions, reducing the risk of running into a disaster.
1.2 Example of a BMS in a Real System
1.2.1 LabView Based BMS
A LabView (Laboratory Virtual Instrument Engineering Workbench) based BMS provides easy execution on a PC. A LabView from the National Instruments Corporation is a software development application that uses a graphical programming language to create programs in a block diagram. Since a LabView includes libraries of functions for data acquisition, serial instrument control, data analysis, data presentation, and data storage, it is recommended for the BMS application. A BMS designed using LabView offers higher flexibility and much better graphic tools for data visualization. The central unit of a LabView based BMS consists of the following blocks:
- Data Processing
- Parameter Adaptation
- Monitoring
- Management
The central unit and input/output interfaces have been recognized as a LabView application.
Due to the flexible design of the LabView BMS, the system is able to perform control and surveillance activities for any kind of battery application and battery technology (e.g. Pb, VRLA, NiCd, NiMH, etc.) [11].
1.2.2 PLC Based BMS
The PLC (programmable logic controller) plays an important role in the field of industrial automation because of its excellent performance. Its multiple functions include logic arithmetic, calculation, communication, noise resistance, and stability. A PLC based BMS design is shown in Figure 1.2. The analog and digital data from the battery were passed to PLC on real time. This system controls the battery charging and discharging.
Figure 1.2 Schematic diagram of a PLC based BMS.
It can be seen that the PLC controls the action of relays and delivers the signal to the...
