Review on State of Charge Estimation Methods for Li-Ion Batteries

Zhang, Xiaoqiang,Zhang, Weiping,Li, Hongyu,Zhang, Mao The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.3

The state of charge (SOC) is an important parameter in a battery-management system (BMS), and is very significant for accurately estimating the SOC of a battery. Li-ion batteries boast of excellent performance, and can only remain at their best working state by means of accurate SOC estimation that gives full play to their performances and raises their economic benefits. This paper summarizes some measures taken in SOC estimation, including the discharge experiment method, the ampere-hour integral method, the open circuit voltage method, the Kalman filter method, the neural network method, and electrochemical impedance spectroscopy (EIS. The principles of the various SOC estimation methods are introduced, and their advantages and disadvantages, as well as the working conditions adopted during these methods, are discussed and analyzed.

A New Single-Stage Small Power MH lamp Electronic Ballast

Zhang, Xiaoqiang,Zhang, Weiping,Zhang, Mao The Korean Institute of Electrical and Electronic 2016 Transactions on Electrical and Electronic Material Vol.17 No.2

In this study, we proposed a new single-stage small power MH lamp electronic ballast and power-factor correction circuit with improved circuit by the current of passive power factor correction. Main circuit integrates traditional DC/DC and DC/AC circuits into one-stage DC/AC inverter. Moreover, we described the working principle and control strategy of the new circuit; it's soft switching principle; and resonant element parameter design formula. An experimental prototype of HID lamp electronic ballast with output power of 70 W was built to verify the feasibility of the analysis and design. The simulation and experimental results proved that the power factor of this circuit could reach 94%, with efficiency of 90%. The input current harmonics conform to IEC 61000-3-2 standards and its cost is low. These superior performances of the new circuit indicate certain practical values.

A New Single-Stage Small Power MH lamp Electronic Ballast

Xiaoqiang Zhang,Wei-ping Zhang,Mao Zhang 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.2

In this study, we proposed a new single-stage small power MH lamp electronic ballast and power-factor correction circuit with improved circuit by the current of passive power factor correction. Main circuit integrates traditional DC/DC and DC/AC circuits into one-stage DC/AC inverter. Moreover, we described the working principle and control strategy of the new circuit; it’s soft switching principle; and resonant element parameter design formula. An experimental prototype of HID lamp electronic ballast with output power of 70 W was built to verify the feasibility of the analysis and design. The simulation and experimental results proved that the power factor of this circuit could reach 94%, with efficiency of 90%. The input current harmonics conform to IEC 61000-3-2 standards and its cost is low. These superior performances of the new circuit indicate certain practical values.

A Novel Model of a Li-ion Battery Based on the Manufacturer's Datasheet

Zhang, Xiaoqiang,Zhang, Weiping,Zhang, Mao The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.5

A novel battery model based on the manufacturer datasheet is proposed. According to this model, not only the steady state but also the dynamic charging performance of the Li-ion battery can be analyzed and evaluated. The major advantage of our model is that all the parameters can be directly obtained from the datasheet and no additional experiments are required. Moreover, the transition between charge and discharge stages was analyzed based on our model, and a novel Simulink module was built to predict the energy consumption of a battery-powered system. Experiments were carried out to verify the model accuracy. Although the new model was developed for the Li-ion battery, it is expected to be applicable to other batteries.

Fundamental Small-signal Modeling of Li-ion Batteries and a Parameter Evaluation Using Levy's Method

Zhang, Xiaoqiang,Zhang, Mao,Zhang, Weiping The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

The fundamental small-signal modeling of lithium-ion (Li-ion) batteries and a parameter evaluation approach are investigated in this study to describe the dynamic behaviors of small signals accurately. The main contributions of the study are as follows. 1) The operational principle of the small signals of Li-ion batteries is revealed to prove that the sinusoidal voltage response of a Li-ion battery is a result of a sinusoidal current stimulation of an AC small signals. 2) Three small-signal measurement conditions, namely stability, causality, and linearity, are proved mathematically proven to ensure the validity of the frequency response of the experimental data. 3) Based on the internal structure and electrochemical operational mechanism of the battery, an AC small-signal model is established to depict its dynamic behaviors. 4) A classical least-squares curve fitting for experimental data, referred as Levy's method, are introduced and developed to identify small-signal model parameters. Experimental and simulation results show that the measured frequency response data fit well within reading accuracy of the simulated results; moreover, the small-signal parameters identified by Levy's method are remarkably close to the measured parameters. Although the fundamental and parameter evaluation approaches are discussed for Li-ion batteries, they are expected to be applicable for other batteries.

Fundamental Small-signal Modeling of Li-ion Batteries and a Parameter Evaluation Using Levy’s Method

Xiaoqiang Zhang,Mao Zhang,Weiping Zhang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

The fundamental small-signal modeling of lithium-ion (Li-ion) batteries and a parameter evaluation approach are investigated in this study to describe the dynamic behaviors of small signals accurately. The main contributions of the study are as follows. 1) The operational principle of the small signals of Li-ion batteries is revealed to prove that the sinusoidal voltage response of a Li-ion battery is a result of a sinusoidal current stimulation of an AC small signals. 2) Three small-signal measurement conditions, namely stability, causality, and linearity, are proved mathematically proven to ensure the validity of the frequency response of the experimental data. 3) Based on the internal structure and electrochemical operational mechanism of the battery, an AC small-signal model is established to depict its dynamic behaviors. 4) A classical least-squares curve fitting for experimental data, referred as Levy’s method, are introduced and developed to identify small-signal model parameters. Experimental and simulation results show that the measured frequency response data fit well within reading accuracy of the simulated results; moreover, the small-signal parameters identified by Levy’s method are remarkably close to the measured parameters. Although the fundamental and parameter evaluation approaches are discussed for Li-ion batteries, they are expected to be applicable for other batteries.

Review on State of Charge Estimation Methods for Li-Ion Batteries

Xiaoqiang Zhang,Wei-ping Zhang,Hongyu Li,Mao Zhang 한국전기전자재료학회 2017 Transactions on Electrical and Electronic Material Vol.18 No.3

The state of charge (SOC) is an important parameter in a battery-management system (BMS), and is very significantfor accurately estimating the SOC of a battery. Li-ion batteries boast of excellent performance, and can only remainat their best working state by means of accurate SOC estimation that gives full play to their performances and raisestheir economic benefits. This paper summarizes some measures taken in SOC estimation, including the dischargeexperiment method, the ampere-hour integral method, the open circuit voltage method, the Kalman filter method,the neural network method, and electrochemical impedance spectroscopy (EIS. The principles of the various SOCestimation methods are introduced, and their advantages and disadvantages, as well as the working conditionsadopted during these methods, are discussed and analyzed.

A Novel Model of a Li-ion Battery Based on the Manufacturer’s Datasheet

Xiaoqiang Zhang,Weiping Zhang,Mao Zhang 한국전기전자재료학회 2017 Transactions on Electrical and Electronic Material Vol.18 No.5

A novel battery model based on the manufacturer datasheet is proposed. According to this model, not only the steady state but also the dynamic charging performance of the Li-ion battery can be analyzed and evaluated. The major advantage of our model is that all the parameters can be directly obtained from the datasheet and no additional experiments are required. Moreover, the transition between charge and discharge stages was analyzed based on our model, and a novel Simulink module was built to predict the energy consumption of a battery-powered system. Experiments were carried out to verify the model accuracy. Although the new model was developed for the Li-ion battery, it is expected to be applicable to other batteries.

A Simplified Li-ion Battery SOC Estimating Method

Xiaoqiang Zhang,Xiaocheng Wang,Wei-ping Zhang,Geyang Lei 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.1

The ampere-hour integral method and the open circuit voltage method are integrated via the extended Kalman filter method so as to overcome insufficiencies of the ampere-hour integral method and the open circuit voltage method for estimating battery SOC. The process noise covariance and the measurement noise covariance of the extended Kalman filter method are simplified based on the Thevenin equivalent circuit model, with a proposed simplified SOC estimating method. Verification of DST experiments indicated that the battery SOC estimating method is simple and feasible, and the estimated SOC error is no larger than 2%.

A Review of Factors Affecting the Lifespan of Lithium-ion Battery and its Health Estimation Methods

Xiaoqiang Zhang,Yue Han,Wei-ping Zhang 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.5

With the widespread application of large-capacity lithium batteries in new energy vehicles, real-time monitoring the status of lithium batteries and ensuring the safe and stable operation of lithium batteries have become a focus of research in recent years. A lithium battery’s State of Health (SOH) describes its ability to store charge. Accurate monitoring the status of a lithium battery allows the Battery Management System (BMS) to timely adjust the working voltage, charge and discharge current, and heat dissipation efficiency. Lithium batteries have the characteristics of high energy density, high rated voltage, and low self-discharge rate. Improper use can cause accidents such as spontaneous combustion and explosion. The key to ensure stable and safe operations of a lithium battery in a system is to quickly and accurately estimate the SOH of the lithium battery. In this paper, the definition of SOH of lithium battery and the factors affecting the aging of lithium batteryare introduced. Current and predominant methods for estimating the SOH of lithium batteries are summarized. Finally, based on the problems and challenges of current SOH estimation methods of lithium battery, future research directions and emphasis areas are proposed.