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Zhichao He

Bio: Zhichao He is an academic researcher from Tsinghua University. The author has contributed to research in topics: Battery (electricity) & State of charge. The author has an hindex of 4, co-authored 7 publications receiving 35 citations.

Papers
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Proceedings ArticleDOI
Wei Liu1, Xiaofeng Sun1, Haisang Wu2, Zhichao He2, Geng Yang2 
22 May 2016
TL;DR: In this article, the authors proposed a charging method for Li-ion battery bank to balance both energy loss and charging time, where the energy loss function is simplified and an objective equation is proposed for balancing charging time and energy loss.
Abstract: A useful fast charging method should make a balance between battery's safety/cycle life and charging time. So, the internal temperature or energy loss of battery should be controlled in charging process. This paper proposes a charging method for Li-ion battery bank to balance both energy loss and charging time. Firstly, the method gives a procedure to get the function of the internal direct current (DC) resistances varying with state of charge (SOC) and charging currents. Then the energy loss function is simplified and an objective equation is proposed for balancing charging time and energy loss. Finally, for real time implementation, a multistage current charging curve is designed with different weight factors in each stage. Experiment shows the advantages of the method.

11 citations

Wei Liu1, Xiaofeng Sun1, Haisang Wu2, Zhichao He2, Geng Yang2 
01 Jan 2016
TL;DR: In this paper, the authors proposed a charging method for Li-ion battery bank to balance both energy loss and charging time, where the energy loss function is simplified and an objective equation is proposed for balancing charging time and energy loss.
Abstract: A useful fast charging method should make a balance between battery's safety/cycle life and charging time. So, the internal temperature or energy loss of battery should be controlled in charging process. This paper proposes a charging method for Li-ion battery bank to balance both energy loss and charging time. Firstly, the method gives a procedure to get the function of the internal direct current (DC) resistances varying with state of charge (SOC) and charging currents. Then the energy loss function is simplified and an objective equation is proposed for balancing charging time and energy loss. Finally, for real time implementation, a multistage current charging curve is designed with different weight factors in each stage. Experiment shows the advantages of the method.

10 citations

Patent
23 Nov 2016
TL;DR: In this paper, a method of building a battery DC inner resistance function is presented, which comprises the following steps: corresponding battery inner resistance data of a battery under different battery SOCs (State of Charge), multiple different charging/discharging currents and multiple different ambient temperatures are acquired; according to the acquired battery inner resistances data, a function of the battery dc inner resistance relative to the battery SUs, the charging and discharging currents, and the ambient temperatures is built; a heat production model, a heat transfer model and a heat dissipation model for the battery are built
Abstract: The invention provides a method of building a battery DC inner resistance function. The method comprises the following steps: corresponding battery DC inner resistance data of a battery under different battery SOCs (State of Charge), multiple different charging/discharging currents and multiple different ambient temperatures are acquired; according to the acquired battery DC inner resistance data, a function of the battery DC inner resistance relative to the battery SOCs, the charging/discharging currents and the ambient temperatures is built; a heat production model, a heat transfer model and a heat dissipation model for the battery are built, and according to the heat production model, the heat transfer model and the heat dissipation model, the surface temperature of the battery is predicted in real time; and according to the function of the battery DC inner resistance relative to the battery SOCs, the currents and the ambient temperatures and the surface temperature of the battery, a function of the battery DC inner resistance relative to the battery SOCs, the charging/discharging currents and the surface temperature of the battery is built. The function relationship between the battery SOCs, the current and the surface temperature of the battery and the battery DC inner resistance can be described simply, comprehensively, accurately and in real time, realization is easy, and engineering applications are facilitated.

10 citations

Proceedings ArticleDOI
Zhichao He1, Geng Yang1, Geng Hua1, Na Shen2, Zhanjiang Wang2 
21 Nov 2013
TL;DR: In this article, a simple method for modeling the discharge characteristics of the battery is proposed, where the basic patterns of discharge curves and their relationship with discharge current are analyzed and verified with experiments on valve-regulated lead-acid (VRLA) batteries.
Abstract: Modeling the external characteristics of the battery precisely is a basic issue for effective battery management in energy storage systems. It is difficult because many inherent factors influence the external characteristics, but only few information, such as terminal voltage, current and surface temperature, can be obtained for modeling. This paper proposes a simple method for modeling the discharge characteristics of the battery. The basic patterns of discharge curves and their relationship with discharge current are analyzed. A mathematic model is built based on the method .The model is verified with experiments on valve-regulated lead-acid (VRLA) batteries.

7 citations

Patent
27 Apr 2016
TL;DR: In this paper, a control method for energy storage equipment of a charger system is presented, which can be accessed to an existing charger fabricated according to the national standard; charge and discharge can be simply controlled according to requirements; the charged states, the lifetime and the batteries of the energy storage unit can be estimated by detecting the parameters of charge-discharge currents of the batteries, an environmental temperature and the like; and these contents are managed.
Abstract: The invention discloses a control method for energy storage equipment of a charger system. An energy storage unit controller carries out corresponding control on an energy storage DC converter according to a voltage of a DC bus, an AC voltage of a power distribution network, input and output DC current signals of a battery pack, battery and environment temperatures, parameter setting of the system from the outside, a given battery lifetime model and a control algorithm, so that an energy storage unit carries out charge-discharge operation; and meanwhile, the energy storage unit controller records the operation result. The control method has the advantages that the hardware cost is relatively appropriate; the control method can be simply accessed to an existing charger fabricated according to the national standard; charge and discharge can be simply controlled according to the requirements; the charged states, the lifetime and the like of the batteries of the energy storage unit can be estimated by detecting the parameters of charge-discharge currents of the batteries, an environmental temperature and the like; and these contents are managed.

2 citations


Cited by
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Journal ArticleDOI
TL;DR: A brief review on several key technologies of BMS, including battery modelling, state estimation and battery charging, followed by the introduction of key technologies used in BMS.
Abstract: Batteries have been widely applied in many high-power applications, such as electric vehicles (EVs) and hybrid electric vehicles, where a suitable battery management system (BMS) is vital in ensuring safe and reliable operation of batteries. This paper aims to give a brief review on several key technologies of BMS, including battery modelling, state estimation and battery charging. First, popular battery types used in EVs are surveyed, followed by the introduction of key technologies used in BMS. Various battery models, including the electric model, thermal model and coupled electro-thermal model are reviewed. Then, battery state estimations for the state of charge, state of health and internal temperature are comprehensively surveyed. Finally, several key and traditional battery charging approaches with associated optimization methods are discussed.

338 citations

Journal ArticleDOI
TL;DR: In this article, the authors illustrate the various fast charging techniques that are being used to charge the lithium-ion batteries in electric vehicles and compare them in terms of the charging time, the charging efficiency, and battery life.
Abstract: The objective of this article is to illustrate the various fast charging techniques that are being used to charge the lithium-ion batteries in electric vehicles. Various charging protocols such as constant current, constant voltage, constant current constant voltage, multistage constant current, varying current method, pulse charging methods are critically reviewed and explained in their broader perspective of fundamental concepts to their modeling/simulation. Amongst, the constant current constant voltage charging approach is considered as a benchmark for other charging protocols in terms of the charging time, the charging efficiency, and battery life. A critical comparison among the various charging methods mentioned above are discussed and possible future research directions in the design and development of new fast charging techniques have been proposed based on the commercial and societal demands.

37 citations

Proceedings ArticleDOI
13 Jun 2018
TL;DR: A technological roadmap for this fast-developing area of lithium-ion batteries is explored and it is clear that there are several opportunities for improvements in this area.
Abstract: The growing demand for battery electric vehicles has expedited the need for new charging approaches to improve speed and reliability of the charging process. DC fast charging has shown great potential to meet the requirement. However, it also brings significant challenges to the current technologies in terms of battery chemistry, charging profile, power electronics converter topologies, and grid impact. This paper explores a technological roadmap for this fast-developing area and evaluates challenges and advancements. A detailed overview of lithium-ion batteries discusses several candidates for DC fast charging along with thermal management for the battery pack design. The selection of charging algorithm is also very important, and several potential candidates have been developed, which are compared. Based on the study, it is clear that there are several opportunities for improvements in this area. The modular design of power converter is essential, and new wide-bandgap materials shall play an important role.

26 citations

Journal ArticleDOI
TL;DR: This paper investigates intelligent optimization methodology to improvise the existing approaches in order to speed up the charging process whilst reducing the energy consumption without degradation in the light of the outrageous demand for lithium-ion battery in the electric vehicles (EVs).
Abstract: Fast charging of the electric-vehicles is one of the paramount challenges in solar smart cities. This paper investigates intelligent optimization methodology to improvise the existing approaches in order to speed up the charging process whilst reducing the energy consumption without degradation in the light of the outrageous demand for lithium-ion battery in the electric vehicles (EVs). Two fitness functions are combined as the targeted objective function: energy losses (EL) and charging interval time (CIT). An intelligent optimization methodology based on Cuckoo Optimization Algorithm (COA) is implemented to the objective function for improving the charging performance of the lithium-ion battery. COA is applied through two main techniques: The Hierarchical technique (HT) and the Conditional random technique (CRT). The experimental results show that the proposed techniques permit a full charging capacity of the polymer lithium-ion battery (0 to 100% SOC) within 91 mins. Compared with the constant current-constant voltage (CCCV) technique, an improvement in the efficiency of 8% and 14.1% was obtained by the Hierarchical technique (HT) and the Conditional random technique (CRT) respectively, in addition to a reduction in energy losses of 7.783% and 10.408% respectively and a reduction in charging interval time of 18.1% and 22.45% respectively. Experimental and theoretical analyses are performed and are in good agreement on the polymer lithium-ion battery fast charging method.

22 citations

Journal ArticleDOI
Qi Wang1, Xiaoyi Feng1, Bo Zhang, Tian Gao1, Yan Yang1 
TL;DR: A new SOC estimation method based on Extended Kalman Filter (EKF), combined with the current integration method and the open circuit voltage method, is proposed, which has high accuracy and good robustness, and the estimated error of SOC of the power battery is less than 4%, which can meet the practical requirements of engineering application.
Abstract: State of Charge (SOC) is one of the main parameters to characterize the power battery state. The accurate SOC estimation has a great impact on predicting the mileage of vehicles, prolonging the battery life, and improving the efficiency of electric vehicles. At present, the common SOC estimation methods have some shortcomings in accuracy, real time, and operability. In this paper, a new SOC estimation method based on Extended Kalman Filter (EKF), combined with the current integration method and the open circuit voltage method, is proposed. Taking lead-acid power batteries as the research object, the Thevenin equivalent circuit model of battery is established. The model parameters are identified by Hybrid Pulse Power Characterization (HPPC), then, the new algorithm based on EKF is used to estimate the state of the power battery, and the experimental verification is carried out. The experimental results show that the algorithm has high accuracy and good robustness, and the estimated error of SOC of the power battery is less than 4%, which can meet the practical requirements of engineering application.

18 citations