This page has only limited features, please log in for full access.

Unclaimed
Zhijian Fang
School of Automation, China University of Geosciences, 12564 Wuhan, Hubei, China

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 07 April 2021 in IEEE Transactions on Vehicular Technology
Reads 0
Downloads 0

An onboard energy storage system (OESS) with fast energy-exchange ability is needed to enable future grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operations. To facilitate the fast energy exchange, the OESS normally interfaces between a high voltage (HV) bus on the grid side and a low voltage (LV) bus on the vehicle side. The HV bus can be up to 1200 V, while the LV bus is as low as 48 V, which means a high conversion ratio is needed. Resonant converters are commonly used for OESS and designed with large characteristic impedance for wide-range output power and zero-voltage-switching operation. However, such a design leads to large volume and complex customization of the magnetic components. In this paper, a high conversion-ratio OESS is proposed, which is based on interleaved quasi-resonant converters with small characteristic impedance. The resonant converters are modularly designed with a small characteristic impedance to achieve small volume, low cost, and simple customization, and interleaved in LV-side-parallel and HV-side-series configuration for high conversion ratio. Moreover, modulated in quasi-resonant operations, all the switches can realize soft switching even at light load conditions for high efficiency. Burst control for output regulation is implemented in each modular quasi-resonant converter, while interleaved control is implemented between them to minimize the current ripple. The proposed design and control are validated by a compact 5 kW prototype with a charging/discharging current of 100 A, high power efficiency of 98.91%, a high power density of 3.86 W/cm^3, and high-conversion-ratio (up to 20: 1) power flow between a 1000 VDC HV bus and a 48 VDC LV bus.

ACS Style

Zhijian Fang; Zhiguo Wei; Zhicong Huang; Fei Liu. Onboard Energy Storage System Based on Interleaved High-Conversion-Ratio Quasi-Resonant Converter With Small Characteristic Impedance. IEEE Transactions on Vehicular Technology 2021, 70, 4238 -4251.

AMA Style

Zhijian Fang, Zhiguo Wei, Zhicong Huang, Fei Liu. Onboard Energy Storage System Based on Interleaved High-Conversion-Ratio Quasi-Resonant Converter With Small Characteristic Impedance. IEEE Transactions on Vehicular Technology. 2021; 70 (5):4238-4251.

Chicago/Turabian Style

Zhijian Fang; Zhiguo Wei; Zhicong Huang; Fei Liu. 2021. "Onboard Energy Storage System Based on Interleaved High-Conversion-Ratio Quasi-Resonant Converter With Small Characteristic Impedance." IEEE Transactions on Vehicular Technology 70, no. 5: 4238-4251.

Journal article
Published: 18 December 2019 in IEEE Transactions on Industrial Electronics
Reads 0
Downloads 0

Load-independent output with zero-phase-angle (ZPA) input is desirable in wireless inductive power transfer (IPT) converters for effective power transfer, but it usually greatly relies on the parameters of the loosely coupled transformer, normally fixed or constrained by space. Thus, customizable outputs cannot be readily achieved unless a new transformer is redesigned. In this paper, we elaborate the rather complex relationships among compensation parameters, customizable load-independent-voltage (LIV) outputs with ZPA input, power efficiency and overall compensation capacitance cost of the series/series-parallel (S/SP) IPT converter. We present a cost-effective compensation design to free the customization of LIV outputs from a parameter-constrained loosely coupled transformer, with optimization between efficiency enhancement and overall compensation capacitance cost. We conducted the proposed design supported by experimental results in S/SP IPT converters with an identical loosely coupled transformer and various sets of compensation capacitors. We compared with a conventional design, the proposed design provides custom ranges of LIV outputs in both a weak and a relatively strong coupling condition, with over 5.9% and 5% efficiency improvement, respectively. The overall compensation capacitance can also be reduced by up to 37% and 21.5%, respectively.

ACS Style

Zhicong Huang; Zhijian Fang; Chi-Seng Lam; Pui-In Mak; Rui Paulo Martins. Cost-Effective Compensation Design for Output Customization and Efficiency Optimization in Series/Series-Parallel Inductive Power Transfer Converter. IEEE Transactions on Industrial Electronics 2019, 67, 10356 -10365.

AMA Style

Zhicong Huang, Zhijian Fang, Chi-Seng Lam, Pui-In Mak, Rui Paulo Martins. Cost-Effective Compensation Design for Output Customization and Efficiency Optimization in Series/Series-Parallel Inductive Power Transfer Converter. IEEE Transactions on Industrial Electronics. 2019; 67 (12):10356-10365.

Chicago/Turabian Style

Zhicong Huang; Zhijian Fang; Chi-Seng Lam; Pui-In Mak; Rui Paulo Martins. 2019. "Cost-Effective Compensation Design for Output Customization and Efficiency Optimization in Series/Series-Parallel Inductive Power Transfer Converter." IEEE Transactions on Industrial Electronics 67, no. 12: 10356-10365.

Journal article
Published: 06 December 2019 in IEEE Transactions on Vehicular Technology
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (2):1428-1439.

Chicago/Turabian Style

Hang 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.

Journal article
Published: 04 April 2019 in IEEE Access
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (99):47339-47352.

Chicago/Turabian Style

Shiqi 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.

Journal article
Published: 01 January 2019 in IEEE Access
Reads 0
Downloads 0

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.

ACS Style

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 Style

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.

Chicago/Turabian Style

Zhongyu 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.

Journal article
Published: 25 October 2018 in AIP Advances
Reads 0
Downloads 0
ACS Style

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 Style

Shiqi 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 Style

Shiqi 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.

Journal article
Published: 16 October 2018 in IEEE Access
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (99):60881-60890.

Chicago/Turabian Style

Zhongzheng 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.

Journal article
Published: 24 September 2018 in IEEE Access
Reads 0
Downloads 0

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.

ACS Style

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 Style

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.

Chicago/Turabian Style

Zhongyu 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.

Journal article
Published: 24 July 2018 in IEEE Transactions on Power Electronics
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (5):4807-4819.

Chicago/Turabian Style

Zhijian 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.

Journal article
Published: 02 May 2018 in Energies
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (5):1124.

Chicago/Turabian Style

Junhao 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.

Journal article
Published: 01 May 2018 in AIP Advances
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (5):055004.

Chicago/Turabian Style

Junhua 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.

Journal article
Published: 07 March 2018 in Energies
Reads 0
Downloads 0

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.

ACS Style

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 Style

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 (3):579.

Chicago/Turabian Style

Zhijian 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.

Article
Published: 05 March 2018 in Cluster Computing
Reads 0
Downloads 0

With the popularity of computer, people currently use computers more and more frequently, and the human being surrounded by ubiquitous electromagnetic field. Therefore, people pay increasing attention to the harm of electromagnetic wave antennas to the health of human body. Computer electromagnetic radiation carcinogenic doses was studied through Monte Carlo algorithm. Simulation calculation was conducted on the electromagnetic dose absorbed by head in the near field of computer through Monte Carlo procedure Geant4 and simulation model of the human body, and from the aspects of radiation flux and the effective dose of human body. Besides, the SAR distribution of the human body exposed to far field of mobile communication base station antenna and human body head exposed to near field of mobile communication base station antenna was explored when radiation system launched at peak power. Besides, the calculated results were compared with existing international and domestic hygiene standards.

ACS Style

Haoli Hou; Junhua Wang; Yi Xu; Zhijian Fang; Zhongyu Dai. RETRACTED ARTICLE: Computer electromagnetic radiation carcinogenic doses based on Monte Carlo algorithm. Cluster Computing 2018, 22, 9047 -9047.

AMA Style

Haoli Hou, Junhua Wang, Yi Xu, Zhijian Fang, Zhongyu Dai. RETRACTED ARTICLE: Computer electromagnetic radiation carcinogenic doses based on Monte Carlo algorithm. Cluster Computing. 2018; 22 (S4):9047-9047.

Chicago/Turabian Style

Haoli Hou; Junhua Wang; Yi Xu; Zhijian Fang; Zhongyu Dai. 2018. "RETRACTED ARTICLE: Computer electromagnetic radiation carcinogenic doses based on Monte Carlo algorithm." Cluster Computing 22, no. S4: 9047-9047.

Journal article
Published: 27 February 2018 in IEEE Access
Reads 0
Downloads 0

Magnetic resonant coupling (MRC) wireless power transfer (WPT) technology provides a novel solution to the tricky power-charging issue of densely connected sensor devices in the age of Internet of Things. Due to the cost and space constraints, the one-to-one MRC WPT is not suitable for charging the large number of sensor devices. The one-to-many MRC WPT requires less cost and space, but all receivers receive the power emitted from the transmitter disregarding the receivers' needs, which will lead to the accelerated aging even damage or malfunction of the receivers. In this paper, we propose a selective omnidirectional MRC WPT with multiple-receiver system. The power transmitted by an omnidirectional transmitter composed of three orthogonal circular coils will be received by any receiver located nearby. As the number of the transmitters reduces, the cost and space declines. Based on the band pass filter principle, the receivers selectively acquire the power at a designated frequency, which improves the energy efficiency and increase equipment service life. Moreover, for the proposed model, its magnetic field distribution of the simulation and physical experiments are carefully designed and performed, and their results are examined and analyzed in detail. They all confirm the capabilities of selective power transferring and the omnidirectional power transfer of the MRC WPT.

ACS Style

Zhongyu Dai; Zhijian Fang; Hong Huang; YuanJian He; Junhua Wang. Selective Omnidirectional Magnetic Resonant Coupling Wireless Power Transfer With Multiple-Receiver System. IEEE Access 2018, 6, 19287 -19294.

AMA Style

Zhongyu Dai, Zhijian Fang, Hong Huang, YuanJian He, Junhua Wang. Selective Omnidirectional Magnetic Resonant Coupling Wireless Power Transfer With Multiple-Receiver System. IEEE Access. 2018; 6 ():19287-19294.

Chicago/Turabian Style

Zhongyu Dai; Zhijian Fang; Hong Huang; YuanJian He; Junhua Wang. 2018. "Selective Omnidirectional Magnetic Resonant Coupling Wireless Power Transfer With Multiple-Receiver System." IEEE Access 6, no. : 19287-19294.

Journal article
Published: 21 September 2017 in Energies
Reads 0
Downloads 0

The gain of a LLC resonant converter can vary with the loads that can be used to improve the efficiency and power density for some special applications, where the maximum gain does not apply at the heaviest loads. However, nonlinear gain characteristics can make the converters unstable during a major disturbance. In this paper, the stability of an LLC resonant converter during a major disturbance is studied and a trigger control scheme is proposed to improve the converter’s stability by extending the converter’s operational range. Through in-depth analysis of the gain curve of the LLC resonant converter, we find that the switching frequency range is one of the key factors determining the system’s stability performance. The same result is also obtained from a mathematical point of view by utilizing the mixed potential function method. Then a trigger control method is proposed to make the LLC resonant converter stable even during a major disturbance, which can be used to extend the converter’s operational range. Finally, experimental results are given to verify the analysis and proposed control scheme.

ACS Style

Zhijian Fang; Junhua Wang; Shanxu Duan; Jianwei Shao; Guozheng Hu. Stability Analysis and Trigger Control of LLC Resonant Converter for a Wide Operational Range. Energies 2017, 10, 1448 .

AMA Style

Zhijian Fang, Junhua Wang, Shanxu Duan, Jianwei Shao, Guozheng Hu. Stability Analysis and Trigger Control of LLC Resonant Converter for a Wide Operational Range. Energies. 2017; 10 (10):1448.

Chicago/Turabian Style

Zhijian Fang; Junhua Wang; Shanxu Duan; Jianwei Shao; Guozheng Hu. 2017. "Stability Analysis and Trigger Control of LLC Resonant Converter for a Wide Operational Range." Energies 10, no. 10: 1448.

Journal article
Published: 22 February 2017 in IEEE Transactions on Power Electronics
Reads 0
Downloads 0

LLC resonant converter is a nonlinear system, limiting the use of typical linear control methods. This paper proposed a new nonlinear control strategy, using load feedback linearization for an LLC resonant converter. Compared with the conventional PI controllers, the proposed feedback linearized control strategy can achieve better performance with elimination of the nonlinear characteristics. The LLC resonant converter's dynamic model is built based on fundamental harmonic approximation using extended describing function. By assuming the dynamics of resonant network is much faster than the output voltage and controller, the LLC resonant converter's model is simplified from seven-order state equations to two-order ones. Then, the feedback linearized control strategy is presented. A double loop PI controller is designed to regulate the modulation voltage. The switching frequency can be calculated as a function of the load, input voltage, and modulation voltage. Finally, a 200 W laboratory prototype is built to verify the proposed control scheme. The settling time of the LLC resonant converter is reduced from 38.8 to 20.4 ms under the positive load step using the proposed controller. Experimental results prove the superiority of the proposed feedback linearized controller over the conventional PI controller.

ACS Style

Zhijian Fang; Junhua Wang; Shanxu Duan; Kaipei Liu; Tao Cai. Control of an LLC Resonant Converter Using Load Feedback Linearization. IEEE Transactions on Power Electronics 2017, 33, 887 -898.

AMA Style

Zhijian Fang, Junhua Wang, Shanxu Duan, Kaipei Liu, Tao Cai. Control of an LLC Resonant Converter Using Load Feedback Linearization. IEEE Transactions on Power Electronics. 2017; 33 (1):887-898.

Chicago/Turabian Style

Zhijian Fang; Junhua Wang; Shanxu Duan; Kaipei Liu; Tao Cai. 2017. "Control of an LLC Resonant Converter Using Load Feedback Linearization." IEEE Transactions on Power Electronics 33, no. 1: 887-898.

Journal article
Published: 10 December 2014 in IEEE Transactions on Power Electronics
Reads 0
Downloads 0

In this paper, an LLC resonant converter design methodology for battery charging applications is proposed aiming at achieving high efficiency. Compared with traditional resistive or constant power load applications, the battery voltage and current are nonlinear and vary with the charging profiles, making the optimal design of battery charger more difficult and complicated. Based on the characteristics of the battery charging profiles, a new time-weighted average efficiency (TWAE) index is proposed, which represents the average weight of conversion efficiency during battery charging period. Converter's losses are calculated based on the standard loss models using the current and voltage information derived from the LLC steady-state model, which is solved utilizing the numerical non-linear programming techniques. In addition, the TWAE is achieved serving as the objective function to optimize the converter parameters. To reduce the search space and speed up the search algorithm, a variable-step exhaustive search algorithm is applied considering the constraints of operation and variable range. Finally, a 3 kW prototype LLC converter, which converts 220 VAC from the grid to a wide output voltage range from 60 to 100 V is built and a TWAE of 94.74% and a peak efficiency of 95.19% are achieved, validating the effectiveness of the presented method.

ACS Style

Zhijian Fang; Tao Cai; Shanxu Duan; Changsong Chen. Optimal Design Methodology for LLC Resonant Converter in Battery Charging Applications Based on Time-Weighted Average Efficiency. IEEE Transactions on Power Electronics 2014, 30, 5469 -5483.

AMA Style

Zhijian Fang, Tao Cai, Shanxu Duan, Changsong Chen. Optimal Design Methodology for LLC Resonant Converter in Battery Charging Applications Based on Time-Weighted Average Efficiency. IEEE Transactions on Power Electronics. 2014; 30 (10):5469-5483.

Chicago/Turabian Style

Zhijian Fang; Tao Cai; Shanxu Duan; Changsong Chen. 2014. "Optimal Design Methodology for LLC Resonant Converter in Battery Charging Applications Based on Time-Weighted Average Efficiency." IEEE Transactions on Power Electronics 30, no. 10: 5469-5483.

Conference paper
Published: 01 March 2013 in 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
Reads 0
Downloads 0

LLC resonant converter has been used widely in DC-DC converters for constant output voltage with high efficiency. However, most of the design methods based on fundamental harmonic approximation (FHA) can't be used for the design of charging converter of Li-Ion batteries as the output voltage of Li-Ion batteries charger is wide. In this paper, an optimal design method for LLC resonant converter has been developed. The objective of this optimal design method is maximizing the magnetizing inductance. The relationship between the operation range and circuit parameters has been revealed based on the frequency response of the converter. Maximum conversion efficiency is achieved under the normal condition by using the maximum magnetizing inductance. A numerical method is developed based on the LLC converter's steady state equations to eliminate the limitation that the FHA method fails to describe voltage gain characteristic more precisely. A 3kW prototype LLC converter with output voltage ranging from 50V to 100V is built according to the proposed optimization method. Simulation results show that the proposed converter can achieve the higher efficiency than the conventional method. Furthermore, the full load efficiency of a 3kW prototype is about 94.5%.

ACS Style

Zhijian Fang; Shanxu Duan; Changsong Chen; Xi Chen; Jianxing Zhang. Optimal design method for LLC resonant converter with wide range output voltage. 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC) 2013, 2106 -2111.

AMA Style

Zhijian Fang, Shanxu Duan, Changsong Chen, Xi Chen, Jianxing Zhang. Optimal design method for LLC resonant converter with wide range output voltage. 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC). 2013; ():2106-2111.

Chicago/Turabian Style

Zhijian Fang; Shanxu Duan; Changsong Chen; Xi Chen; Jianxing Zhang. 2013. "Optimal design method for LLC resonant converter with wide range output voltage." 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC) , no. : 2106-2111.