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Wireless charging for electric vehicles has been investigated in recent years. One of the critical issues of the research is to improve the weak interoperability between two popular charging pads—rectangular pad (RCP) and double-D pad (DDP). This article intends to model the interoperability under pad misalignment and improve it by adjusting the pads’ relative position. First, the variation of interoperability with pad misalignment is analyzed by the flux model. Full output power and high transmission efficiency can be achieved when the two pads are misaligned to a certain distance. Second, the optimal misalignment is obtained by flux calculation and simulation. Third, an adaptive position adjustment method for the transmitting pad based on the variable-step perturbation and observation algorithm is proposed. By searching the maximum dc input current, the optimal position of the transmitting pad can be found. Finally, in the experiment, a 3.3 kW output with 95% coil-coil efficiency is realized when the RCP and DDP interoperate at the optimal position. Compared with the scenario without position adjustment, the improvement of output power and efficiency proves that the proposal can optimize the interoperability between the RCP and DDP.

Three-phase meander-type dynamic wireless power transfer is ideal for the power supply or charging of rail vehicles. However, there is a lack of systematic analysis and design of the three-phase receiver. To achieve the compact design of the three-phase receiver in practical applications, this article studies the compact three-phase receiver with overlapped receiving coils and ferrite core. Based on the analysis of the fundamental coupling characteristic of three-phase meander-type dynamic wireless power transfer, two overlap modes of the receiving coils are concluded and compared. Meanwhile, by considering the influence of mutual inductance harmonic distortion, the accuracy of the receiving coil analysis and design is improved. Furthermore, a practical distributed strip core design is presented to enhance the coupling between transmitting coils and receiving coils. Additionally, the effect of the core on coupling imbalance is analyzed in detail and proves to have little effect on the power transfer. Afterward, a design flow of star-connected series-compensated receiver with the overlapped coils and the distributed strip core is proposed. Finally, for verification, a small prototype with an average output power of 154 W and average efficiency of 97% of the receiving coils is established.

In recent years, due to the strong autonomous learning ability of neural network algorithms, they have been applied for electrical impedance tomography (EIT). Although their imaging accuracy is greatly improved compared with traditional algorithms, generalization for both simulation and experimental data is required to be improved. According to the characteristics of voltage data collected in EIT, a one-dimensional convolutional neural network (1D-CNN) is proposed to solve the inverse problem of image reconstruction. Abundant samples are generated with numerical simulation to improve the edge-preservation of reconstructed images. The TensorFlow-graphics processing unit environment and Adam optimizer are used to train and optimize the network, respectively. The reconstruction results of the new network are compared with the Deep Neural Network (DNN) and 2D-CNN to prove the effectiveness and edge-preservation. The anti-noise and generalization capabilities of the new network are also validated. Furthermore, experiments with the EIT system are carried out to verify the practicability of the new network. The average image correlation coefficient of the new network increases 0.0320 and 0.0616 compared with the DNN and 2D-CNN, respectively, which demonstrates that the proposed method could give better reconstruction results, especially for the distribution of complex geometries.

State of energy (SOE) is an important index for the electrochemical energy storage system in electric vehicles. In this paper, a robust state of energy estimation method in combination with a physical model parameter identification method is proposed to achieve accurate battery state estimation at different operating conditions and different aging stages. A physics-based fractional order model with variable solid-state diffusivity (FOM-VSSD) is used to characterize the dynamic performance of a LiFePO4/graphite battery. In order to update the model parameter automatically at different aging stages, a multi-step model parameter identification method based on the lexicographic optimization is especially designed for the electric vehicle operating conditions. As the battery available energy changes with different applied load current profiles, the relationship between the remaining energy loss and the state of charge, the average current as well as the average squared current is modeled. The SOE with different operating conditions and different aging stages are estimated based on an adaptive fractional order extended Kalman filter (AFEKF). Validation results show that the overall SOE estimation error is within ±5%. The proposed method is suitable for the electric vehicle online applications.

In this paper, a dynamic RF position detection system that uses RF signals to realize real-time switching control of the segmented rails of the dynamic wireless power supply system of electric vehicles is designed. And a RF detection circuit with PCB directional antenna is designed, the communication distance can be controlled within a certain range by adjusting the transmitting power and receiving sensitivity of the circuit. The good penetration and anti-jamming ability of the system are verified by experiments.

Wireless charging technology for electric vehicles (EVs) has been investigated by lots of researchers. One of the key points of the technology is to ensure the interoperability between different vehicle assembly (VA) and ground assembly (GA). This paper describes the interoperability of different coils using coupling coefficient and efficiency by theoretical calculation, simulation and experiments. It is concluded that the interoperability between rectangular and DD coils is related to relative position of coils. Therefore, an adaptive position adjustment method using P&O algorithm and coupling coefficient estimation is proposed. By searching the optimal charging location, the output power and efficiency can be high when DD coil charges with rectangular coil. The experimental results agree with the theoretical analysis, which implies that the interoperability between two coils is improved by the proposed method.

This paper proposes an interoperability evaluation method for wireless electric vehicle charging (WEVC) systems based on coil ampere-turns. Firstly, the concept of interoperability is introduced and parameters to evaluate interoperability are compared. Interoperability of different coils is also analyzed and concluded. Secondly, the theoretical background of coil ampere-turns is presented and the relationship between coil ampere-turns and interoperability is established. Thirdly, the standard devices are introduced and standard zone of coil ampere-turns is plotted. Interoperability of any vehicle assembly (VA) and ground assembly (GA) can be verified by coil ampere-turns test using standard devices. Only if the measured coil ampere-turns is within the standard zone can interoperability be confirmed. Finally, the theoretical analysis is validated by simulation, demonstrating the effectiveness and simplicity of the proposed method.

Owing to cell-to-cell variations in battery pack, it is hard to manage cells of the battery pack safely and effectively. As a result, the battery pack performance is rapidly degraded, which in turn spread the differences in individual cells. Ambient temperature is a significant factor that influences the characteristics of lithium-ion battery and cell variations in the pack. This study tries to put effort in researching the temperature characteristics of cells series battery pack. The battery model parameters identification tests are designed to analyse the inconsistency characteristics of cells [such as open-circuit voltage (OCV), ohmic and polarisation resistances and polarisation capacitance] under various ambient temperatures. The results indicate that ohmic and polarisation resistances are most significantly increased as the temperature decreases, whereas OCV is opposite. The variation of cells inconsistency characteristics is obvious along with the temperature change. Comprehensive above factors, the change rate of battery pack capacity is faster than that of a single cell with the drop in temperature.

Effective capacity-loss diagnosis and life-time prediction are the foundations of battery second-use technology and will play an important role in the development of the new energy industry. Of the two, the capacity-loss diagnostic, as a precondition of the life-time prediction, needs to be studied first. Performing a capacity-loss diagnosis for an aging cell consists of finding the decisive degradation mechanisms for the cell's capacity degradation. Because a cell's capacity just equals the span of the open-circuit voltage (OCV), when suspect degradation mechanisms affect a cell's capacity, they will leave corresponding and particular clues in the OCV curve. Taking a cell's OCV as the diagnostic indicator, a multi-mechanistic and non-destructive diagnostic method is developed in this paper. To establish an unambiguous relationship between OCV changes and the combinations of the decisive mechanisms, all the possible OCV changes under various aging situations are systematically analyzed based on a novel simultaneous coordinate system, in which the effects of each suspect capacity-loss mechanism on the OCV curve can be clearly represented. As a summary of the analysis results, a straightforward diagnostic flowchart is presented. By following the flowchart, an aging cell can be diagnosed within three steps by observation of the OCV changes.

This paper presents a novel grouping method for lithium iron phosphate batteries. In this method, a simplified electrochemical impedance spectroscopy (EIS) model is utilized to describe the battery characteristics. Dynamic stress test (DST) and fractional joint Kalman filter (FJKF) are used to extract battery model parameters. In order to realize equal-number grouping of batteries, a new modified K-means clustering algorithm is proposed. Two rules are designed to equalize the numbers of elements in each group and exchange samples among groups. In this paper, the principles of battery model selection, physical meaning and identification method of model parameters, data preprocessing and equal-number clustering method for battery grouping are comprehensively described. Additionally, experiments for battery grouping and method validation are designed. This method is meaningful to application involving the grouping of fresh batteries for electric vehicles (EVs) and screening of aged batteries for recycling.

In this letter, a novel two-coil magnetic communication method based on magnetic resonant coupling and frequency divarication is proposed. The half-power decay is employed to derive the boundary condition of double 3-dB bandwidths. Moreover, the expressions of load power, power ratio, and communication capacity are deduced based on the mutual inductance theory. The theory proves that there exists one common peak value for the bandwidth and communication capacity. Also, the expression of peak value of the maximum capacity is derived using the boundary condition. The experimental results demonstrate that the proposed magnetic communication method has a maximum bandwidth and communication capacity at a wide frequency range, especially at low frequency.

This study describes an online estimation of the model parameters and state of charge (SOC) of lithium iron phosphate batteries in electric vehicles. A widely used SOC estimator is based on the dynamic battery model with predeterminate parameters. However, model parameter variances that follow with their varied operation temperatures can result in errors in estimating battery SOC. To address this problem, a battery online parameter estimator is presented based on an equivalent circuit model using an adaptive joint extended Kalman filter algorithm. Simulations based on actual data are established to verify accuracy and stability in the regression of model parameters. Experiments are also performed to prove that the proposed estimator exhibits good reliability and adaptability under different loading profiles with various temperatures. In addition, open-circuit voltage (OCV) is used to estimate SOC in the proposed algorithm. However, the OCV based on the proposed online identification includes a part of concentration polarization and hysteresis, which is defined as parametric identification-based OCV (OCV PI ). Considering the temperature factor, a novel OCV–SOC relationship map is established by using OCV PI under various temperatures. Finally, a validating experiment is conducted based on the consecutive loading profiles. Results indicate that our method is effective and adaptable when a battery operates at different ambient temperatures.

For a wireless power transfer system, when the transmission distance is long, the power is low in the case of low coupling coefficient. In order to solve this problem, a new compensate topology of primary side based on parallel T-type structure is proposed. The circuit structure and impedance characteristics of the system are analyzed, the compensation circuit can be used to make the primary side be equivalent to series resonant structure with a proportionally amplified Q value. The expression of the output voltage in the proposed structure, is deduced and compared with traditional series resonant structure. Simulation and experimental data show that compared with series-series structure, the proposed topology can increase transmission power as the coupling coefficient changes, and is more suitable for long distance power transmission.

The design of a physics-based reduce-order battery model is especially desired by the automotive researchers and engineers due to the demand of battery system diagnosis and prognostics. Taking the problem into account, three physics- based electrochemical models include Pseudo two dimensional (P2D) model, extended single particle (ESP) model, single particle (SP) model are analyzed in this paper. The internal overpotential components are analyzed under six operating conditions. Results show that the SP model is appropriate for close-to-equilibrium OCV test condition; the ESP model is appropriate for slow charging, typical charging and driving cycle operating conditions; the P2D model is suitable for high C-rate constant current or pulse current discharge conditions. The analysis result method and result is meaningful for model order reduction.

Typical working conditions and application scenes of backup batteries for communication base station in China are analyzed in this article. And the mathematical model is established for economic analysis of the application of second-use of electric vehicle batteries in backup power for Chinese communication base station. The cost savings ratio in different remaining cycle life of second-use electric vehicle batteries compared with using lead-acid batteries are calculated at a price of 1.1 CNY/Wh and 0.7 CNY/Wh respectively. Analysis results show economy is remarkably influenced by remaining cycle life in new energy scene and its effect is weaker than calendar life and purchase price in other scenes.

Wireless power transfer (WPT) system has been introduced to many applications. However, it allows very limited misalignment of the power receiver relative to the power transmitter, which is not suitable for some applications such as electric vehicle (EV) wireless charging. This paper presents methods to improve output stability over large misalignment from the perspective of compensation topology and magnetic coupler. For compensation topology, multi-level non-resonant topology is proposed and analyzed. By adjusting the component of the topology, output power can be modified. For magnetic coupler, solenoid type coil is applied with a quadrature pick-up in order to stabilize coupling coefficient. Experiment results show that proposed design methods can stabilize transmission power against a wide range of misalignment.

This paper proposes a secondary side hysteretic Pulse Width Modulation (PWM) control technique that employs a switch and hysteresis comparator to realize constant current charging for the variable load. The switch parallels with the secondary side rectifier and is controlled by the hysteretic PWM signals. Two working modes, named as short circuit mode and rectify mode, are used to adjust the power flows into the load. The advantages of the proposed technique are that dual-side wireless communication for power adjustment is avoided and the circuit is simplified compared with commonly used secondary- side dc-dc converter. The influence of vertical and horizontal misalignment on charging current are also analyzed and verified. Both the simulation and experimental results are presented to validate the proposed technique, and the desired constant current charging for variable load is realized.

This paper focuses on the design of secondary control loop in wireless EV charging system according to model calculation instead of empirical estimation or simulation attempt. To simplify the structure of secondary circuit, semi-bridgeless active rectifier is used. The analysis and modeling of semi- bridgeless active rectifier is completed by small-signal modeling method. The secondary control loop with quick response and high stability is designed based on Bode plot analysis of the open- loop system. The response time to 80% output power change is less than 2 ms with less than 10% disturbance in resonant circuits. The principle verification is completed by simulation of the designed control loop in wireless charging system.

This paper compares the characteristics of serial, parallel and LCC compensation topologies of secondary-side in wireless powering systems with a constant-current primary-side. The topologies characteristics of power, efficiency and load are carefully analyzed and detailed presented. And the correctness of theoretical analysis is verified by simulations. This study results can guide the selection of compensation topology in practical application.

In this paper, we propose a mid-range wireless power transfer system with CCL type resonant topology on source side for monitoring equipment power supply on electricity pylons. In consideration of low coupling coefficient caused by long transmission distance, a relatively high current level should be kept when using the traditional serial-serial topology(referred to as S-S topology), which increases the system energy loss and rise the breakdown risk on switching devices. The CCL topology could provide a relatively high equivalent impedance and still keeps the current on transfer coil high enough. The characteristic of this topology and the analysis of system efficiency at different load are given. The experiment result shown at in last part proves the availability of this topology.

Wireless power transfer (WPT) systems with square shaped ferrite core are widely used in various applications because of its simplicity. However, it allows very limited lateral misalignment of the power receiver relative to the power transmitter and suffers from big amount of magnetic cores, which is not suitable for some applications such as electric vehicle wireless charging. This paper presents a novel magnetic coupler characterized by its high lateral misalignment tolerance and fewer magnetic cores. Methods to enhance lateral misalignment tolerance are analyzed and simulated.

The aim of this study was to evaluate effects of intermediate frequency magnetic fields (IFMF) generated by a wireless power transmission (WPT) based on magnetic resonance from the perspective of cellular genotoxicity on cultured human lens epithelial cells (HLECs). We evaluated the effects of exposure to 90 kHz magnetic fields at 93.36 µT on cellular genotoxicity in vitro for 2 and 4 h. The magnetic flux density is approximately 3.5 times higher than the reference level recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. For assessment of genotoxicity, we studied cellular proliferation, apoptosis and DNA damage by Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis, alkaline comet assay and phosphorylated histone H2AX (γH2AX) foci formation test. We did not detect any effect of a 90 kHz IFMF generated by WPT based on magnetic resonance on cell proliferation, apoptosis, comet assay, and γH2AX foci formation test. Our results indicated that exposure to 90 kHz IFMF generated by WPT based on magnetic resonance at 93.36 µT for 2 and 4 h does not cause detectable cellular genotoxicity. Bioelectromagnetics. 35:512–518, 2014. © 2014 Wiley Periodicals, Inc.

The goal of this study is to realize real-time predictions of the peak power/state of power (SOP) for lithium-ion batteries in electric vehicles (EVs). To allow the proposed method to be applicable to different temperature and aging conditions, a training-free battery parameter/state estimator is presented based on an equivalent circuit model using a dual extended Kalman filter (DEKF). In this estimator, the model parameters are no longer taken as functions of factors such as SOC (state of charge), temperature, and aging; instead, all parameters will be directly estimated under the present conditions, and the impact of the temperature and aging on the battery model will be included in the parameter identification results. Then, the peak power/SOP will be calculated using the estimated results under the given limits. As an improvement to the calculation method, a combined limit of current and voltage is proposed to obtain results that are more reasonable. Additionally, novel verification experiments are designed to provide the true values of the cells' peak power under various operating conditions. The proposed methods are implemented in experiments with LiFePO 4 /graphite cells. The validating results demonstrate that the proposed methods have good accuracy and high adaptability.

The open-circuit voltage (OCV) of batteries is a crucial characteristic parameter that reflects many aspects of a battery's performance, such as capacity, state-of-charge (SOC) and state-of-health. OCV is most widely used to determine the SOC when the battery works in a charge-depleting state. However, the application of the OCV to SOC estimation can be difficult because of the need for a long rest time for full relaxation. In this study, based on the analysis on the curve shape of battery voltage relaxation, a new adaptive model for simulating the voltage relaxation process is developed to predict the final static OCV in a few minutes instead of via the traditional long-term rest method. Avoiding this disadvantage, the SOC can be deduced from the predicted OCV via the corresponding relationship obtained in a short amount of time. A working condition experiment is performed to validate the new methods and the results are very accurate.

The supercapacitor, because of its advantages of high specific power, quick charging or discharging with high current rates, and long cycle life, is an interesting choice for energy storage for applications where high power is needed for only a few seconds, such as pulse-power supply systems. Based on the use of supercapacitors all around the world, more and more attention is focused on the effects of temperature on their performance metrics such as capacitance, internal resistance, and efficiency. To predict the terminal voltage of supercapacitors at different temperatures, a three-branch RC equivalent circuit model is improved in this paper, and it can predict the terminal voltage up to 5 to 10 min after completion of charging or discharging. Initially, a typical three-branch RC equivalent circuit model without temperature parameter is used to simulate the pulse charging and discharging behavior of a specific commercial supercapacitor. Next, with the pulse charging and discharging experiment results under ${-}{\rm 40}^{\circ}{\rm C}$ , ${-}{\rm 20}^{\circ}{\rm C}$ , 0 $^{\circ}{\rm C}$ , and 20 $^{\circ}{\rm C}$ , all parameters in the circuit model are reset to a function of temperature, and the temperature dependence of parameters is discussed in detail and determined numerically. Finally, for the purpose of validating the correctness and the accuracy of the improved model, compared study of simulation results and experiment curves is done. Comparison results show that the fitting accuracy of the improved equivalent circuit model is satisfied in pulse charging and discharging at different temperature.

In this paper, a compact wireless energy and data transmission device, which can be used on the remote projectile, is described. This device uses a magnetic field generated by the coupled coil to receive the energy and data and transfer the internal data. These functions above can be realized by operating the control circuit in different modes, which requires only one coil in the projectile. In energy transmission mode, energy can be transferred into the projectile wirelessly, as well as the external data by data encoding technology. A high-frequency magnetic field is generated by an internal device when the internal data are delivered to the external receiver coil. Interference between the energy and data transmission can be avoided by adjusting the data resonant frequency, which is different from the energy transfer frequency, by changing the resonant circuit topology and the internal capacitance. The device works at zero voltage switching mode and produces lower loss, which is beneficial for improving the efficiency. The experiment results show that the device can transfer energy at 1 MHz and internal data at 500 kHz.

In order to improve the distance, power, and efficiency of power transfer in wireless power transfer system under the weak coupling condition, a 3-coil weak coupling power transmission model was created. A new match adjustment method of the Impedance network is raised based on the usage of impedance transformation of the relay. Adjusting the distance of the coil gives the maximum efficiency on the premise of constant load; lastly, an experiment system with PCB coils at frequency of 6.78MHz was designed. The effect of the impedance transformation of the repeating coil has been verified through simulations and measurement. The experimental results are consistent with the theoretical calculations throughout the experimental.

In a parallel-connected battery group (PCBG), capacity degradation is usually caused by the inconsistency between a faulty cell and other normal cells, and the inconsistency occurs due to two potential causes: an aging inconsistency fault or a loose contacting fault. In this paper, a novel method is proposed to perform online and real-time capacity fault diagnosis for PCBGs. Firstly, based on the analysis of parameter variation characteristics of a PCBG with different fault causes, it is found that PCBG resistance can be taken as an indicator for both seeking the faulty PCBG and distinguishing the fault causes. On one hand, the faulty PCBG can be identified by comparing the PCBG resistance among PCBGs; on the other hand, two fault causes can be distinguished by comparing the variance of the PCBG resistances. Furthermore, for online applications, a novel recursive-least-squares algorithm with restricted memory and constraint (RLSRMC), in which the constraint is added to eliminate the “imaginary number” phenomena of parameters, is developed and used in PCBG resistance identification. Lastly, fault simulation and validation results demonstrate that the proposed methods have good accuracy and reliability.

The energy efficiency for electric vehicle battery is affected by many factors. Through the definition of energy efficiency we find the relationship between energy efficiency, voltage efficiency and coulomb efficiency. The factors such as current, internal resistance, SOC and temperature which affect coulomb efficiency and voltage efficiency, will affect energy efficiency as well. An equation is given to show how internal resistance and current influence the energy efficiency. The relationship between these factors and energy efficiency was analyzed through theory and experimental data. This will show ways to increase battery energy efficiency and improve the battery performance.

It has been shown that none of any energy sources which own high specific energy or high specific power, but not both, can solely fulfil all the demands of hybrid electric vehicle (HEV) in some circumstances. In this paper a simulation model for battery/ultra-capacitor hybrid energy storage system (B/UC HESS) was presented by Matlab/Simulink. Based on the model a low-pass filtering control strategy which adopts ultra-capacitor as load leveling device was developed with a goal of improving battery life. The simulation results under different urban driving cycles show the validity of the model. The peak charge/discharge currents are smoothed effectively, which benefits the battery lifetime improvement. The experiment results also show that the buffering effect of ultra-capacitor has optimized the charging and discharging processes of Ni-MH battery considerably.

Battery state of charge is related with available capacity. Battery available capacity varies with temperature and discharge current. A good way to forecast available capacity is Peukert’s equation. In order to verify the practicability of Peukert’s equation at room temperature and low temperature, 1/3C, 1C, 2C, 3C rate discharge experiments were undertaken. The result indicates Peukert’s equation is suitable for estimating available battery of NiMH battery in 25 °C. The result also indicates, at low temperatures, Peukert’s equation is practical for NiMH battery at low current and unpractical in high current. Based on the result, a piece-wise Peukert’s equation with Temperature Correction Factor to NiMH Battery State of Charge (SOC) estimation has been proposed. The proposed method improves the precision of SOC estimantion.

Super capacitor has the advantage of quick charge, large power density, and long cycle life. The shortage is the lower energy density compared with electrochemistry batteries. These features make it suitable for a short-distance electric bus used in the city. Because of the capacitance difference between the capacitor cells, after a number of deep discharging/charging cycles, the voltage difference between cells will be enlarged. This will accelerate the aging of the weak super capacitors and affect the output power. So, a management system with an equalization function is essential. In this paper, a practical super-capacitor stacks management system with dynamic equalization techniques is proposed. The function of the management system includes: monitoring the current, voltage, and temperature of the stacks, control of charge, and discharge with equalization online. A switched-capacitor equalization approach is adopted showing a low-cost way to meet the accuracy requirements. The dynamic equalized charging and discharging circuit is described. The algorithm to increase the operation speed and the precision is analyzed. By dynamically redistributing the current, the equalization procedure can be quicker and more efficient. This approach has been verified by experiments

This paper presents a simple and intuitive method for fault simulation of parallel connected batteries using Simscape. The proposed method can simulate voltage, current and SOC (sate of charge) of each cell, the parameters of the simulation model are obtained through the HPPC (Hybrid Pulse Power Characteristic) test. For fault analysis, parallel connected batteries are equivalent to a single battery using online parameter identification. The fault conditions, such as pure ohmic internal resistance increase and available capacity decrease, are simulated. Parallel connected batteries' voltage, cell's SOC, parallel connected batteries' identified ohmic resistance and parallel connected batteries' identified open circuit voltage are analyzed through contrastive analysis between different fault conditions. The effect of different fault conditions on voltage inconsistency and SOC inconsistency are compared through simulation.

The battery performance deterioration at low temperature attracts more attention. In order to improve the performance at low temperature, a discharge thermal model with external heating is proposed. Discharging tests with and without heating are taken respectively at -27℃ and -17℃. The pack energy enhancement ratio is proposed for the first time to evaluate the discharge energy promotion effect with external heating. Experimental results show that discharging with heating at low temperature is efficient to improve the battery temperature and performance.

This paper proposed a new method of state of peak power capability prediction for Li-ion battery. Electrochemical impedance spectroscopy based equivalent circuit model is used as the reference model of battery dynamic characterization simulation, state of peak power capability is predicted based on the model and parameters estimation by fractional joint Kalman filter. By decomposing the voltage response of peak state to zero state and zero input responses, the peak terminal voltage can be predicted. Then, the state of battery peak power capability can be forecast quickly under the constant load current assumption.

Battery parameter identification is a foundation of dynamic estimations for battery performance states, such as state of charge (SOC) and state of health (SOH), which are key factors in ensuring a battery system's effectiveness, safety and reliability. In this study, a real-time and training- free method is developed to identify such parameters as open-circuit voltage, internal resistances, and polarization capacitance of a first- order resistance-capacitance (RC) circuit model on line. The state-space equations are formulated according to model's dynamic characteristics, and an extended Kalman filter (EKF) algorithm is employed for the parameter identification only using the measured current and voltage of batteries. Federal Urban Driving Schedule (FUDS) cycles are performed in validation experiments on LiFePO4 cells. The results demonstrate the accuracy and regression of the proposed algorithm. Additionally, the algorithm was successfully applied in a battery management system (BMS) with a low computational complexity.

The LiFePO4 batteries are widely used in Electric Vehicle(EV)/Hybrid Electric Vehicle(HEV) because of the high energy and power density. However, high environment temperature could accelerate the aging of batteries, while low temperature could reduce output power capability. Therefore, optimal working temperature for batteries should be determined to maintain good performance in all kinds of tough conditions. In this paper, the optimal working temperature range for batteries is analyzed. The capacity loss model is applied to determine the upper limit. The lower limit is calculated taking available capacity and output power loss into consideration. Simulation and experimental results show that the working temperature range between 10℃ and 40℃ could ensure the performance and available capacity.

Due to cell-to-cell variations in battery pack, it is hard to manage cells of the battery pack safely and effectively. As a result, the battery pack performance is rapidly degraded, which in turn spread the differences in individual cells. Ambient temperature is a significant factor that influences characteristics of lithium-ion battery and cells variations in the pack. This paper tries to put effort on researching the temperature characteristics of cells series battery pack. The battery model parameters identification tests are designed to analyze the inconsistency characteristics of cells (such as open circuit voltage (OCV), ohmic and polarization resistances, and polarization capacitance) under various ambient temperatures. The results indicate that ohmic and polarization resistances are most significantly increased as the temperature decreases, while the opposite is true for OCV. The variation of cells inconsistency characteristics is obvious along with the temperature change.

The aim of this study was to evaluate effects of intermediate frequency magnetic fields (IFMF) generated by a wireless power transmission (WPT) based on magnetic resonance from the perspective of cellular genotoxicity on cultured human lens epithelial cells (HLECs). We evaluated the effects of exposure to 90 kHz magnetic fields at 93.36 µT on cellular genotoxicity in vitro for 2 and 4 h. The magnetic flux density is approximately 3.5 times higher than the reference level recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. For assessment of genotoxicity, we studied cellular proliferation, apoptosis and DNA damage by Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis, alkaline comet assay and phosphorylated histone H2AX (γH2AX) foci formation test. We did not detect any effect of a 90 kHz IFMF generated by WPT based on magnetic resonance on cell proliferation, apoptosis, comet assay, and γH2AX foci formation test. Our results indicated that exposure to 90 kHz IFMF generated by WPT based on magnetic resonance at 93.36 µT for 2 and 4 h does not cause detectable cellular genotoxicity.

State of health (SOH) estimation for Lithium-ion batteries is a core technology of battery management systems, which is a foundation of ensuring system's safety and reliability. An accurate SOH estimation reflects the present fraction of allowable performance left before the end of life. In this paper, quantization standards of SOH are introduced firstly and some suggestions are proposed to solve the inconformity issue of SOH definitions. Then the battery aging phenomenon is interpreted theoretically, which contains the analyses of the aging mechanism, the changes of parameters during aging processes and the factors of accelerating aging. Next, some main methods of the SOH estimation are summarized and compared with each other. And finally, this paper describes the development trend of SOH estimation algorithm.