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Precise health diagnostics and prognostics for batteries which can improve the reliability and efficiency of energy storage technologies are significant. It is still a challenge to predict and diagnose state-of-health (SOH) of batteries due to the complicated and unobservable electrochemical reaction inside the batteries. In this paper, a novel battery health estimation frame-work based on an optimized multiple health indicators (MHIs) system using fuzzy comprehensive evaluation (FCE) and im-proved multivariate gray model (IMGM) is proposed. The pro-posed MHIs system which considers different characteristics of batteries is introduced. Health indicators (HIs) including partial incremental capacity curve peak area (PICA) and partial charge time period (PCTP) are extracted and optimized based on the Box-Cox transformation method. On the basis of the MHIs system, the FCE method is proposed for SOH diagnosis, which decrease the impact of dispersion of different batteries. In addition, an IMGM method is proposed for battery health prognostics considering the coupling relationship between MHIs and battery aging. The MHIs work together on the health prognostics, reducing the impact of the error of any HI on the overall prediction result. The experiments results indicate that the pro-posed methods show good performance on battery online health diagnostics and prognostics.
Junhua Wang; Shiqi Liu; Shuxiao Wang; Qisheng Liu; Haolu Liu; Haikuo Zhou; Jia Tang. Multiple Indicators-Based Health Diagnostics and Prognostics for Energy Storage Technologies Using Fuzzy Comprehensive Evaluation and Improved Multivariate Grey Model. IEEE Transactions on Power Electronics 2021, 36, 12309 -12320.
AMA StyleJunhua Wang, Shiqi Liu, Shuxiao Wang, Qisheng Liu, Haolu Liu, Haikuo Zhou, Jia Tang. Multiple Indicators-Based Health Diagnostics and Prognostics for Energy Storage Technologies Using Fuzzy Comprehensive Evaluation and Improved Multivariate Grey Model. IEEE Transactions on Power Electronics. 2021; 36 (11):12309-12320.
Chicago/Turabian StyleJunhua Wang; Shiqi Liu; Shuxiao Wang; Qisheng Liu; Haolu Liu; Haikuo Zhou; Jia Tang. 2021. "Multiple Indicators-Based Health Diagnostics and Prognostics for Energy Storage Technologies Using Fuzzy Comprehensive Evaluation and Improved Multivariate Grey Model." IEEE Transactions on Power Electronics 36, no. 11: 12309-12320.
Batteries used in battery energy storage system (BESS) have a wide lifetime and fast aging process considering the secondary-use applications. The dispersion of the batteries rises rapidly with aging, leading to a decrease in the robustness of the lifetime estimators. In this paper, a novel multiple health indicators (MHIs) system-based battery lifetime estimator, which contains six health indicators (HIs) with different characteristics is proposed. The Back Propagation Neural Network (BPNN) is used to train the relationship between the HIs and lifetime to reduce the dispersion of different batteries. In addition, an empirical degradation model for low-capacity batteries considering different usage factors is proposed, which is significant for optimized design of BESS. Cycling-induced aging tests with different depth of discharge (DOD) and mean state-of-charge (SOC) are performed to verify the accuracy and robust of the proposed estimator. The average errors of the tested batteries are all less than 1.5%, which shows a good performance on accuracy and robustness.
Shiqi Liu; Junhua Wang; Haolu Liu; Qisheng Liu; Jia Tang; Zhongxiang Li. Battery degradation model and multiple-indicators based lifetime estimator for energy storage system design and operation: Experimental analyses of cycling-induced aging. Electrochimica Acta 2021, 384, 138294 .
AMA StyleShiqi Liu, Junhua Wang, Haolu Liu, Qisheng Liu, Jia Tang, Zhongxiang Li. Battery degradation model and multiple-indicators based lifetime estimator for energy storage system design and operation: Experimental analyses of cycling-induced aging. Electrochimica Acta. 2021; 384 ():138294.
Chicago/Turabian StyleShiqi Liu; Junhua Wang; Haolu Liu; Qisheng Liu; Jia Tang; Zhongxiang Li. 2021. "Battery degradation model and multiple-indicators based lifetime estimator for energy storage system design and operation: Experimental analyses of cycling-induced aging." Electrochimica Acta 384, no. : 138294.
Wireless power transfer (WPT) technology is promising for energy harvesting and electronics powering on power towers. This article presents an improved coplanar couplers based WPT system for adaptive energy harvesting on the towers. Magnetic flux analyses of conventional coaxial coils indicate that the significance of the adaptive and extensible performance in this application. Improved coplanar couplers are further proposed to reduce magnetic flux interactions between the WPT and high-voltage components and promote the performances, which include discrete transmitter windings, vertical receiver coil, and high-permeability layers. Related parameters are determined based on a concluded flow from a sequence of simulations. Moreover, performances of the WPT and high-voltage systems under operating conditions are simulated. The design does not break the high-voltage characteristic and shows robust performances from comparisons. Experimental results prove the effectiveness of the design with a 22.53% efficiency and an 18.98 W output power. Such an adaptive insulator-independent energy supply solution can be extended to different high-voltage towers.
Changsong Cai; Junhua Wang; Longyang Wang; Zhaoyang Yuan; Niang Tang; Xuesen Han; Song Wang. Improved Coplanar Couplers Based WPT Systems for Adaptive Energy Harvesting on Power Towers. IEEE Transactions on Electromagnetic Compatibility 2020, PP, 1 -13.
AMA StyleChangsong Cai, Junhua Wang, Longyang Wang, Zhaoyang Yuan, Niang Tang, Xuesen Han, Song Wang. Improved Coplanar Couplers Based WPT Systems for Adaptive Energy Harvesting on Power Towers. IEEE Transactions on Electromagnetic Compatibility. 2020; PP (99):1-13.
Chicago/Turabian StyleChangsong Cai; Junhua Wang; Longyang Wang; Zhaoyang Yuan; Niang Tang; Xuesen Han; Song Wang. 2020. "Improved Coplanar Couplers Based WPT Systems for Adaptive Energy Harvesting on Power Towers." IEEE Transactions on Electromagnetic Compatibility PP, no. 99: 1-13.
Metal object detection (MOD) and detection of position (DoP) of pick-up coils are increasingly critical to the commercialisation of the wireless power transfer system. In this study, a detection scheme based on phase-detection, which can both realise the function of MOD and DoP, is newly introduced. The method is based on the principle that the presence of metal objects and pick-up coils both affect the impedance phase of the detection coil loop. Comparing with the traditional detection methods, which is based on measuring the absolutely value of impedance in detection loop, the malfunction is avoided by adopting phase difference as the criterion of the existence of metal objects and pick-up coils. An inexpensive and high-precision sensing circuit is newly designed to acquire the phase difference accurately. Simulation models and experiments are conducted to verify the feasibility of the proposed detection scheme. The of the detection coil circuit with a coin placed reaches −5.17, while the of other detection coils without metal objects keeps zero. In the meantime, the position of the pick-up coil is identified because the of these detection coils closer to the centre of the pick-up coil varies more significantly while other coils vary slightly.
Liang Li; Junhua Wang; Changsong Cai; Zhongzheng Lin; Meilin Hu; Fan Zhang. Phase‐detection‐based metal objects and pick‐up coils detection scheme without malfunction in wireless power transfer system. IET Electric Power Applications 2020, 14, 2222 -2230.
AMA StyleLiang Li, Junhua Wang, Changsong Cai, Zhongzheng Lin, Meilin Hu, Fan Zhang. Phase‐detection‐based metal objects and pick‐up coils detection scheme without malfunction in wireless power transfer system. IET Electric Power Applications. 2020; 14 (11):2222-2230.
Chicago/Turabian StyleLiang Li; Junhua Wang; Changsong Cai; Zhongzheng Lin; Meilin Hu; Fan Zhang. 2020. "Phase‐detection‐based metal objects and pick‐up coils detection scheme without malfunction in wireless power transfer system." IET Electric Power Applications 14, no. 11: 2222-2230.
This study proposes a misalignment-tolerant integrated inductive power transfer (IPT) system for tram logistics robots and presents an adapted parameter tuning method for the IPT system. A novel dual-purpose coupler, which could undertake the responsibility of power transmission and self-compensation is realised by substituted partially with compensation inductors of inductor–capacitor–capacitor networks, resulting in an integrated and cost-effective system configuration. With the analysis of working principles on the IPT system and considerations of operation conditions on logistics robots, an adapted parameter tuning method is provided to maximise system misalignment tolerance and maintain high efficiency of power transfer. To demonstrate the validity and safety of the proposed system, comparative simulations and security evaluations are conducted by finite element analysis. Besides, the constant-current output characteristic is simulated and proved. Finally, a 60.20 W experimental prototype is built. Results show that the system can operate stably with 87.31% efficiency at well-aligned cases and the power fluctuation is confined below 9% within −120 to 120 mm x -misalignment, −80 to 80 mm y -misalignment, −50 to 12.5 mm z -misalignment, and −30° to 30° rotatory misalignment. It is also verified that the system could operate safely without any secondary side.
Junhua Wang; Haoyue Qu; Bingquan Tao; Changsong Cai; Zhongzheng Lin; Lijun Xie; Fan Zhang. Misalignment‐tolerant integrated IPT systems for tram logistics robots featuring dual‐purpose coupler. IET Electric Power Applications 2020, 14, 1984 -1995.
AMA StyleJunhua Wang, Haoyue Qu, Bingquan Tao, Changsong Cai, Zhongzheng Lin, Lijun Xie, Fan Zhang. Misalignment‐tolerant integrated IPT systems for tram logistics robots featuring dual‐purpose coupler. IET Electric Power Applications. 2020; 14 (10):1984-1995.
Chicago/Turabian StyleJunhua Wang; Haoyue Qu; Bingquan Tao; Changsong Cai; Zhongzheng Lin; Lijun Xie; Fan Zhang. 2020. "Misalignment‐tolerant integrated IPT systems for tram logistics robots featuring dual‐purpose coupler." IET Electric Power Applications 14, no. 10: 1984-1995.
Wireless power transmission (WPT) technology has been regarded as the best solution to the problems of wire power transmission since its concept is described by Tesla. In recent years, with the application of a large number of electrical equipment, the drawbacks of wire power supply has become more prominent. WPT has received wider attention and more development opportunities. As a core part of WPT system, the magnetic coupling mechanism (MCM) is the focus of most of the research. This article reviews and analyzes the design and optimization of MCM of WPT system. It mainly focuses on the forms of MCM designed to meet different power supply requirements, the optimization methods of MCM to improve the performance, and the electromagnetic safety of MCM to ensure the promotion and application of WPT system. For WPT system, the forms of MCM is the basis of WPT, the optimization of MCM is the guarantee of the system performance, and the electromagnetic safety of MCM is the premise of the applications. The review and analysis of this article covers the three cores of MCM. It can provide a reference for research groups, professionals, and investment representatives on WPT.
Zhongyu Dai; Junhua Wang; Haikuo Zhou; Hong Huang. A Review on the Recent Development in the Design and Optimization of Magnetic Coupling Mechanism of Wireless Power Transmission. IEEE Systems Journal 2020, 14, 4368 -4381.
AMA StyleZhongyu Dai, Junhua Wang, Haikuo Zhou, Hong Huang. A Review on the Recent Development in the Design and Optimization of Magnetic Coupling Mechanism of Wireless Power Transmission. IEEE Systems Journal. 2020; 14 (3):4368-4381.
Chicago/Turabian StyleZhongyu Dai; Junhua Wang; Haikuo Zhou; Hong Huang. 2020. "A Review on the Recent Development in the Design and Optimization of Magnetic Coupling Mechanism of Wireless Power Transmission." IEEE Systems Journal 14, no. 3: 4368-4381.
This paper presents a quasi-uniform magnetic coupling based effective-configuration wireless power transfer (WPT) system for drones wider-area charging with multiple extended transmitter coils. The extended transmitter coil with two windings is proposed to cooperate with a small receiver coil for misalignment tolerance with efficient and quasi-uniform coupling. The extended coil is worked out by a simulation-based algorithm, which can be implemented by simple and low-cost procedures. Independent-operating multiple extended coils are designed with overlaps and a dynamic topology for low-cost and robust charging area extension according to performance analyses. Moreover, a novel landed position detection method based on the negative coupling characteristic of the extended coils is proposed for system configuration. The design enables cost-effective charging area extension, and assists to sense the position of drones. A prototype is established with a charging area nearly 20 times the area of the receiver coil. Experimental results prove the feasibility of the design, which can be applied flexibly.
Changsong Cai; Junhua Wang; Hui Nie; Pengcheng Zhang; Zhongzheng Lin; Ying-Guo Zhou. Effective-Configuration WPT Systems for Drones Charging Area Extension Featuring Quasi-Uniform Magnetic Coupling. IEEE Transactions on Transportation Electrification 2020, 6, 920 -934.
AMA StyleChangsong Cai, Junhua Wang, Hui Nie, Pengcheng Zhang, Zhongzheng Lin, Ying-Guo Zhou. Effective-Configuration WPT Systems for Drones Charging Area Extension Featuring Quasi-Uniform Magnetic Coupling. IEEE Transactions on Transportation Electrification. 2020; 6 (3):920-934.
Chicago/Turabian StyleChangsong Cai; Junhua Wang; Hui Nie; Pengcheng Zhang; Zhongzheng Lin; Ying-Guo Zhou. 2020. "Effective-Configuration WPT Systems for Drones Charging Area Extension Featuring Quasi-Uniform Magnetic Coupling." IEEE Transactions on Transportation Electrification 6, no. 3: 920-934.
LLC resonant converters are widely used in On-board Power Converter but the pumping voltage of traditional LLC converter is unavoidable under light-load conditions due to the existence of parasitic parameter. In this paper, an LLC resonant converter with damping split inductor is proposed to improve the light-load regulation capability. The original resonant inductor is divided into two parts in series. Then, a simple damping resistor connected on one part in parallel and the other part can be integrated into the transformer. Using damping split inductor, significant regulation improvements could be achieved under light-load conditions with not any change in control strategy and almost zero hardware cost. In addition, based on impedance analysis of the resonant tank, the effects of the proposed method are analyzed including voltage gain, soft switching characteristics, suppression of high frequency interference components, and system power loss. Moreover, the detailed design process and optimization conditions of the damping split inductor parameters are carefully illustrated. Eventually, the experimental results demonstrate the characteristics mentioned above for the 96 W prototype at the expense of a maximum increase in device loss of 0.85 W.
Hang Jing; Junhua Wang; Zhijian Fang; Lijun Xie. LLC Resonant Converter With Damping Split Inductor Improving Light-Load Regulation Ability. IEEE Transactions on Vehicular Technology 2019, 69, 1428 -1439.
AMA StyleHang Jing, Junhua Wang, Zhijian Fang, Lijun Xie. LLC Resonant Converter With Damping Split Inductor Improving Light-Load Regulation Ability. IEEE Transactions on Vehicular Technology. 2019; 69 (2):1428-1439.
Chicago/Turabian StyleHang Jing; Junhua Wang; Zhijian Fang; Lijun Xie. 2019. "LLC Resonant Converter With Damping Split Inductor Improving Light-Load Regulation Ability." IEEE Transactions on Vehicular Technology 69, no. 2: 1428-1439.
A universal and robust wireless power transfer (WPT) system crossing insulators to feed monitoring terminals on power towers of overhead transmission lines is presented in this study. Analyses of the WPT system crossing high-voltage insulators string indicate that system characteristics and energy loss vary under different insulation conditions. Transfer characteristics of the WPT system with different relative positions between the coils and insulators are analysed to find an insensitive scheme. To achieve a non-interacting and relatively efficient operation under the scenarios, magnetic shielding layers are designed to further isolate the WPT system and insulators. Moreover, the resonant frequency point tracking method of this specific WPT system is studied and implemented to achieve robust transfer efficiency. Experimental results prove the feasibility, and the system displays a robust transfer performance with various high-voltage insulators. Such energy feeding system can be used in disc or composite insulation towers universally with simplified installation methods.
Changsong Cai; Junhua Wang; Hang Jing; Fan Zhang; Pengcheng Zhang; Zhijian Fang; Ying‐Guo Zhou. Universal wireless powered terminals for robust overhead transmission line monitoring. IET Power Electronics 2019, 12, 3739 -3748.
AMA StyleChangsong Cai, Junhua Wang, Hang Jing, Fan Zhang, Pengcheng Zhang, Zhijian Fang, Ying‐Guo Zhou. Universal wireless powered terminals for robust overhead transmission line monitoring. IET Power Electronics. 2019; 12 (14):3739-3748.
Chicago/Turabian StyleChangsong Cai; Junhua Wang; Hang Jing; Fan Zhang; Pengcheng Zhang; Zhijian Fang; Ying‐Guo Zhou. 2019. "Universal wireless powered terminals for robust overhead transmission line monitoring." IET Power Electronics 12, no. 14: 3739-3748.
Magnetic fluid hyperthermia (MFH) adopts the relaxation mechanism of magnetic nanoparticles to heat targeted tumors by coupling magnetic fields and temperature fields. Temperature regulation plays an important role in determining hyperthermia efficacy. It is generally difficult to obtain the distribution of temperature over the whole treatment region during clinical hyperthermia due to the limitations of invasive temperature measurements. To predict the temperature and its distribution during hyperthermia, this paper uses the finite element method and builds a coupled multiphysics model of MFH to analyze the magnetic field and temperature distributions within treated tissue and to determine the influence of the magnetic field strength on the tissue temperature during hyperthermia. The heat dissipation equations are used as inputs to determine the specific loss power of heat sources for nanoparticle injection sites. The results show the distribution of the temperature in the targeted tissue. In addition, an in vitro MFH experiment is subsequently performed with cervical cancer cell cultures. A temperature increase of approximately 4 °C is observed in the tumor tissue treated with Fe2O3 magnetic fluids when the magnetic field is applied for 30 minutes. Hence, the feasibility of hyperthermia and the accuracy of the proposed simulation model are verified with such experimental results.Magnetic fluid hyperthermia (MFH) adopts the relaxation mechanism of magnetic nanoparticles to heat targeted tumors by coupling magnetic fields and temperature fields. Temperature regulation plays an important role in determining hyperthermia efficacy. It is generally difficult to obtain the distribution of temperature over the whole treatment region during clinical hyperthermia due to the limitations of invasive temperature measurements. To predict the temperature and its distribution during hyperthermia, this paper uses the finite element method and builds a coupled multiphysics model of MFH to analyze the magnetic field and temperature distributions within treated tissue and to determine the influence of the magnetic field strength on the tissue temperature during hyperthermia. The heat dissipation equations are used as inputs to determine the specific loss power of heat sources for nanoparticle injection sites. The results show the distribution of the temperature in the targeted tissue. In addition, a...
Yi Xu; Junhua Wang; Haoli Hou; Jianwei Shao. Simulation analysis of coupled magnetic-temperature fields in magnetic fluid hyperthermia. AIP Advances 2019, 9, 105317 .
AMA StyleYi Xu, Junhua Wang, Haoli Hou, Jianwei Shao. Simulation analysis of coupled magnetic-temperature fields in magnetic fluid hyperthermia. AIP Advances. 2019; 9 (10):105317.
Chicago/Turabian StyleYi Xu; Junhua Wang; Haoli Hou; Jianwei Shao. 2019. "Simulation analysis of coupled magnetic-temperature fields in magnetic fluid hyperthermia." AIP Advances 9, no. 10: 105317.
This study presents an extended efficiency control method with resonant frequency tracking, load optimisation and output voltage regulation of extremely loosely coupled wireless power transfer (WPT) systems for smart grid applications. Adaptive resonant frequency tracking of this specified system is proposed and implemented to achieve a robust and efficient transmission efficiency with fast searching and less fluctuation. Automatic load optimisation of the system with the required output is realised to further improve the efficiency by adjusting the phase-shift angle of the converter on the transmitter side. Owing to a receiving feedback circuit, the proposed system does not require any communication which is suited for operating under high-voltage insulation conditions. Input current from source is the only parameter to be sensed for the proposed strategy of extended efficiency control, which makes the method cost-effective and work-robust even in the harsh environments. Experimental results prove the feasibility of the extended efficiency control method, which can be used in wireless powered devices in a smart grid or other extremely loosely coupled WPT systems.
Junhua Wang; Changsong Cai; Liang Li; Pengcheng Zhang; Qisheng Liu; Fan Zhang; Zhijian Fang. Extended efficiency control method for WPT systems in smart grid under loose coupling extremes. IET Power Electronics 2019, 12, 2523 -2533.
AMA StyleJunhua Wang, Changsong Cai, Liang Li, Pengcheng Zhang, Qisheng Liu, Fan Zhang, Zhijian Fang. Extended efficiency control method for WPT systems in smart grid under loose coupling extremes. IET Power Electronics. 2019; 12 (10):2523-2533.
Chicago/Turabian StyleJunhua Wang; Changsong Cai; Liang Li; Pengcheng Zhang; Qisheng Liu; Fan Zhang; Zhijian Fang. 2019. "Extended efficiency control method for WPT systems in smart grid under loose coupling extremes." IET Power Electronics 12, no. 10: 2523-2533.
State of charge (SOC) estimation of deep-discharging Li-ion batteries under complicated working conditions at different temperatures is still challenging. The depth of discharge (DOD) of batteries in electric vehicles (EVs) is generally low nowadays, resulting in the insufficient use of battery energy. This paper proposes a SOC estimation method using a novel partial adaptive forgetting factors recursive least square (PAFFRLS), which adjusts the forgetting factors based on the own physical properties of each pa-rameter in equivalent circuit models (ECMs) to accommodate to greatly changing under deep-discharging range and highly dynamic working conditions. The gain matrix in the proposed method is split to update independently according to each parameter, which solves the issue of mutual influence between parameters vary with different rates. In addition, four typical test profiles including DST, UDDS, US06 and EUDC are employed to simulate different working conditions of EVs. Eventually, numerous simulations and experi-ments at different temperatures are employed to verify the validity of the proposed method. The average errors of the SOC estimation under four different kinds of working conditions are all less than 1.3% as well as the peak errors are all less than 5%. The peak errors are all less than 3% while DOD is larger than 90% which illustrates the effectiveness of the proposed method in the case of deep-discharging and provides a better guidance to the design of battery management system (BMS) in EVs.
Shiqi Liu; Junhua Wang; Qisheng Liu; Jia Tang; Haolu Liu; Zhi-Jian Fang. Deep-Discharging Li-Ion Battery State of Charge Estimation Using a Partial Adaptive Forgetting Factors Least Square Method. IEEE Access 2019, 7, 47339 -47352.
AMA StyleShiqi Liu, Junhua Wang, Qisheng Liu, Jia Tang, Haolu Liu, Zhi-Jian Fang. Deep-Discharging Li-Ion Battery State of Charge Estimation Using a Partial Adaptive Forgetting Factors Least Square Method. IEEE Access. 2019; 7 (99):47339-47352.
Chicago/Turabian StyleShiqi Liu; Junhua Wang; Qisheng Liu; Jia Tang; Haolu Liu; Zhi-Jian Fang. 2019. "Deep-Discharging Li-Ion Battery State of Charge Estimation Using a Partial Adaptive Forgetting Factors Least Square Method." IEEE Access 7, no. 99: 47339-47352.
A full-freedom wireless power transfer for spheroid joints is proposed to solve the problem of power transmission between the caput-articularis and the acetabulum in a spheroid joint. According to the characteristics of the spheroid joint, a hemispherical coil and a spherical coil are designed having no effect on the performance of the joint. Hemispherical and spherical magnetic cores are used to optimize the magnetic field distribution of the transmitter and receiver coils to reduce the electromagnetic influence on the external environment of the acetabulum and the internal environment of the caput-articularis during the power transmission process. Practical results obtained from a hardware prototype are included. They confirm that the maximum transmission efficiency of the designed system is 91%, and the transmission efficiency is always higher than 80% when the caput-articularis rotates freely.
Zhongyu Dai; Junhua Wang; Lei Jin; Hang Jing; Zhijian Fang; Haoli Hou. A Full-Freedom Wireless Power Transfer for Spheroid Joints. IEEE Access 2019, 7, 18675 -18684.
AMA StyleZhongyu Dai, Junhua Wang, Lei Jin, Hang Jing, Zhijian Fang, Haoli Hou. A Full-Freedom Wireless Power Transfer for Spheroid Joints. IEEE Access. 2019; 7 ():18675-18684.
Chicago/Turabian StyleZhongyu Dai; Junhua Wang; Lei Jin; Hang Jing; Zhijian Fang; Haoli Hou. 2019. "A Full-Freedom Wireless Power Transfer for Spheroid Joints." IEEE Access 7, no. : 18675-18684.
Shiqi Liu; Junhua Wang; Zhijian Fang. Improved FEM for distribution network cables rating using multiple forgetting factors least-square. AIP Advances 2018, 8, 105030 .
AMA StyleShiqi Liu, Junhua Wang, Zhijian Fang. Improved FEM for distribution network cables rating using multiple forgetting factors least-square. AIP Advances. 2018; 8 (10):105030.
Chicago/Turabian StyleShiqi Liu; Junhua Wang; Zhijian Fang. 2018. "Improved FEM for distribution network cables rating using multiple forgetting factors least-square." AIP Advances 8, no. 10: 105030.
Wireless power transfer (WPT) technology has become a popular solution to battery charging of mobile equipment. However, the variation of the load power will affect the transmission capacity of the system, which might make the electrical load cannot gain the required rated power and function improperly. Based on the analysis of power transmission characteristic and resonance state of WPT system, this paper adopts the simulated annealing (SA) method to track the maximum power point (MPP) of WPT in bifurcation state. The power tracking effectiveness of the proposed SA method is compared with that of the traditional MPPT method in WPT system based on perturbation and observation. The SA method performances under different parameters are assessed with consideration of the number of iterations needed for convergence and the convergence probability. Experimental validation of the maximum power tracking of WPT based on SA method is presented under different load conditions. Experimental results verify that the proposed SA method realizes the maximum power tracking when the WPT system works in the power bifurcation area, thus making full use of the inverter's VA capacity and approaching a unity power factor.
Zhongzheng Lin; Junhua Wang; Zhijian Fang; Meilin Hu; Changsong Cai; Junkun Zhang. Accurate Maximum Power Tracking of Wireless Power Transfer System Based on Simulated Annealing Algorithm. IEEE Access 2018, 6, 60881 -60890.
AMA StyleZhongzheng Lin, Junhua Wang, Zhijian Fang, Meilin Hu, Changsong Cai, Junkun Zhang. Accurate Maximum Power Tracking of Wireless Power Transfer System Based on Simulated Annealing Algorithm. IEEE Access. 2018; 6 (99):60881-60890.
Chicago/Turabian StyleZhongzheng Lin; Junhua Wang; Zhijian Fang; Meilin Hu; Changsong Cai; Junkun Zhang. 2018. "Accurate Maximum Power Tracking of Wireless Power Transfer System Based on Simulated Annealing Algorithm." IEEE Access 6, no. 99: 60881-60890.
The wireless power transfer technology provides a new solution to the power supply of monitoring devices. By adding a magnetic core that redistributes magnetic circuit, the proportion of the magnetic flux for power transmission increases, which improves the transmission efficiency. Based on a typical wireless power transmission model, the relationships between the parameters of the magnetic coupling mechanism and the transmission efficiency, as well as the parameters and the structure of the magnetic core, are analyzed. Under the premise of maximizing the transmission efficiency, the magnetic core is further optimized and its optimal parameters are designed. Compared with the traditional magnetic coupling mechanism, the proposed magnetic coupling mechanism with optimized magnetic cores improves the transmission efficiency by about 10%. This method indicates a new direction for optimizing the magnetic coupling mechanism of the wireless power supply system for monitoring equipment, as it can be applied to other wirelessly charged devices.
Zhongyu Dai; Junhua Wang; Yida Li; YuanJian He; Zhijian Fang; Haoli Hou. Optimal Design of Magnetic Coupling Wireless Power Supply System for Monitoring Equipment. IEEE Access 2018, 6, 58600 -58608.
AMA StyleZhongyu Dai, Junhua Wang, Yida Li, YuanJian He, Zhijian Fang, Haoli Hou. Optimal Design of Magnetic Coupling Wireless Power Supply System for Monitoring Equipment. IEEE Access. 2018; 6 ():58600-58608.
Chicago/Turabian StyleZhongyu Dai; Junhua Wang; Yida Li; YuanJian He; Zhijian Fang; Haoli Hou. 2018. "Optimal Design of Magnetic Coupling Wireless Power Supply System for Monitoring Equipment." IEEE Access 6, no. : 58600-58608.
LLC resonant converter would have light-load voltage regulation problems due to the effect of parasitic capacitances in high frequency range. In this paper, an energy feedback control method is proposed to improve the light-load regulation capacity by using synchronous rectifiers (SRs). The SR bridges are controlled ahead of the primary inverter bridges to deliver the energy from load to source, reducing the output voltage independent of the load. Then the desired voltage can be achieved even in no load conditions by regulating the operation time of the energy feedback mode. The gain, voltage ripple and efficiency performances of the proposed control method are discussed based on the precise analysis and accurate model of the converter. Moreover, the light-load operations of the LLC resonant converter are analyzed deriving the critical load condition. Finally, the proposed control method is verified by the experiments of a 12V/8A LLC resonant converter prototype.
Zhijian Fang; Junhua Wang; Rong Liu; Liangle Xiao; Junkun Zhang; Guozheng Hu; Qisheng Liu; Guozhen Hu. Energy Feedback Control of Light-Load Voltage Regulation for LLC Resonant Converter. IEEE Transactions on Power Electronics 2018, 34, 4807 -4819.
AMA StyleZhijian Fang, Junhua Wang, Rong Liu, Liangle Xiao, Junkun Zhang, Guozheng Hu, Qisheng Liu, Guozhen Hu. Energy Feedback Control of Light-Load Voltage Regulation for LLC Resonant Converter. IEEE Transactions on Power Electronics. 2018; 34 (5):4807-4819.
Chicago/Turabian StyleZhijian Fang; Junhua Wang; Rong Liu; Liangle Xiao; Junkun Zhang; Guozheng Hu; Qisheng Liu; Guozhen Hu. 2018. "Energy Feedback Control of Light-Load Voltage Regulation for LLC Resonant Converter." IEEE Transactions on Power Electronics 34, no. 5: 4807-4819.
As a key factor in the design of a voltage-adjustable LLC resonant converter, frequency regulation range is very important to the optimization of magnetic components and efficiency improvement. This paper presents a novel optimal design method for LLC resonant converters, which can narrow the frequency variation range and ensure high efficiency under the premise of a required gain achievement. A simplified gain model was utilized to simplify the calculation and the expected efficiency was initially set as 96.5%. The restricted area of parameter optimization design can be obtained by taking the intersection of the gain requirement, the efficiency requirement, and three restrictions of ZVS (Zero Voltage Switch). The proposed method was verified by simulation and experiments of a 150 W prototype. The results show that the proposed method can achieve ZVS from full-load to no-load conditions and can reach 1.6 times the normalized voltage gain in the frequency variation range of 18 kHz with a peak efficiency of up to 96.3%. Moreover, the expected efficiency is adjustable, which means a converter with a higher efficiency can be designed. The proposed method can also be used for the design of large-power LLC resonant converters to obtain a wide output voltage range and higher efficiency.
Junhao Luo; Junhua Wang; Zhijian Fang; Jianwei Shao; Jiangui Li. Optimal Design of a High Efficiency LLC Resonant Converter with a Narrow Frequency Range for Voltage Regulation. Energies 2018, 11, 1124 .
AMA StyleJunhao Luo, Junhua Wang, Zhijian Fang, Jianwei Shao, Jiangui Li. Optimal Design of a High Efficiency LLC Resonant Converter with a Narrow Frequency Range for Voltage Regulation. Energies. 2018; 11 (5):1124.
Chicago/Turabian StyleJunhao Luo; Junhua Wang; Zhijian Fang; Jianwei Shao; Jiangui Li. 2018. "Optimal Design of a High Efficiency LLC Resonant Converter with a Narrow Frequency Range for Voltage Regulation." Energies 11, no. 5: 1124.
Wireless charging is the key technology to realize real autonomy of mobile robots. As the core part of wireless power transfer system, coupling mechanism including coupling coils and compensation topology is analyzed and optimized through simulations, to achieve stable and practical wireless charging suitable for ordinary robots. Multi-layer coil structure, especially double-layer coil is explored and selected to greatly enhance coupling performance, while shape of ferrite shielding goes through distributed optimization to guarantee coil fault tolerance and cost effectiveness. On the basis of optimized coils, primary compensation topology is analyzed to adopt composite LCL compensation, to stabilize operations of the primary side under variations of mutual inductance. Experimental results show the optimized system does make sense for wireless charging application for robots based on magnetic resonance coupling, to realize long-term autonomy of robots.
Junhua Wang; Meilin Hu; Changsong Cai; Zhongzheng Lin; Liang Li; Zhijian Fang. Optimization design of wireless charging system for autonomous robots based on magnetic resonance coupling. AIP Advances 2018, 8, 055004 .
AMA StyleJunhua Wang, Meilin Hu, Changsong Cai, Zhongzheng Lin, Liang Li, Zhijian Fang. Optimization design of wireless charging system for autonomous robots based on magnetic resonance coupling. AIP Advances. 2018; 8 (5):055004.
Chicago/Turabian StyleJunhua Wang; Meilin Hu; Changsong Cai; Zhongzheng Lin; Liang Li; Zhijian Fang. 2018. "Optimization design of wireless charging system for autonomous robots based on magnetic resonance coupling." AIP Advances 8, no. 5: 055004.
In this paper, a rectifier current control for an LLC resonant converter is proposed, based on a simplified, two-order, linearized model that adds a rectifier current feedback inner loop to improve dynamic performance. Compared to the traditional large-signal model with seven resonant states, this paper utilizes a rectifier current state to represent the characteristics of the resonant states, simplifying the LLC resonant model from seven orders to two orders. Then, the rectifier current feedback inner loop is proposed to increase the control system damping, improving dynamic performance. The modeling and design methodology for the LLC resonant converter are also presented in this paper. A frequency analysis is conducted to verify the accuracy of the simplified model. Finally, a 200 W LLC resonant converter prototype is built to verify the effectiveness of the proposed control strategy. Compared to a traditional single-loop controller, the settling time and voltage droop were reduced from 10.8 ms to 8.6 ms and from 6.8 V to 4.8 V, respectively, using the proposed control strategy.
Zhijian Fang; Junhua Wang; Shanxu Duan; Liangle Xiao; Guozheng Hu; Qisheng Liu. Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model. Energies 2018, 11, 579 .
AMA StyleZhijian Fang, Junhua Wang, Shanxu Duan, Liangle Xiao, Guozheng Hu, Qisheng Liu. Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model. Energies. 2018; 11 (3):579.
Chicago/Turabian StyleZhijian Fang; Junhua Wang; Shanxu Duan; Liangle Xiao; Guozheng Hu; Qisheng Liu. 2018. "Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model." Energies 11, no. 3: 579.