Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer （MR-WPT） system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic pe...Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer （MR-WPT） system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic performance in engineering. In this study, the shielding effectiveness of a two-coil MR-WPT system for different material shields is analyzed in theory using Moser＇s formula and Schelkunoff＇s formula. On this basis a candidate magnetic-shielding scheme with a double-layer structure is determined, which has better shielding effectiveness and coils coupling coefficient. Finally, some finite element simulation results validate the correctness of the theoretical analysis, and the shielding effectiveness with the double-layer shield in maximum is 30？dB larger than the one with the single-layer case.展开更多
The equivalent two-port network model of a middle range wireless power transfer(WPT) system was presented based on strongly coupled multiple resonators. The key parameters of the WPT system include self-inductance, re...The equivalent two-port network model of a middle range wireless power transfer(WPT) system was presented based on strongly coupled multiple resonators. The key parameters of the WPT system include self-inductance, resistance, parasitic capacitance, mutual inductance and S-parameters of coils & resonators were analyzed. The impedance matching method was used to optimize load power and transmission efficiency of the multi-resonator WPT system, and the impedance matching method was realized through adjusting the distances between the coils and resonators. Experiments show that the impedance matching method can effectively improve load power and transmission efficiency for middle range wireless power transfer systems with multiple resonators, at distances up to 3 times the coil radius with efficiency more than 70% and load power also close to 3.5 W.展开更多
The optimization method by adjusting load and distances between two adjacent coils( or resonators) is presented on basis of wireless power transfer( WPT) system with relay resonators. 2-port network and impedance matc...The optimization method by adjusting load and distances between two adjacent coils( or resonators) is presented on basis of wireless power transfer( WPT) system with relay resonators. 2-port network and impedance matching theory are applied to analyzing power flow of incidence and reflection in WPT system,then setting up power flow model. The maximum power transmission efficiency can be obtained when the load and distance between secondary resonator and output coil meets impedance matching at 2-port network's output port. The simulation and experimental results shown the impedance matching method can effectively improve and maintain transmission efficiency by adjusting load and distances between coils or relay resonators.展开更多
针对谐振式无线电能传输系统中分数阶电感、电容元件的仿真实现困难的问题,采用等效阻抗实现分数阶电容的等效.基于分数阶电容的阻抗特性,给出了一种分数阶RLC_(α)串联谐振双向无线电能传输(bidirectional wireless power transfer,BD-...针对谐振式无线电能传输系统中分数阶电感、电容元件的仿真实现困难的问题,采用等效阻抗实现分数阶电容的等效.基于分数阶电容的阻抗特性,给出了一种分数阶RLC_(α)串联谐振双向无线电能传输(bidirectional wireless power transfer,BD-WPT)系统结构,通过建立含分数阶电容的串联谐振式双向无线电能传输系统的电路模型,推导了其传输功率和效率关系.仿真实验结果表明,与整数阶串联谐振系统相比,系统的输出功率提升了7.82%,传输效率提升了0.58个百分点.展开更多
风电机组经串、并联补偿并网可以降低线损,并有效提高线路送电功率和系统运行的稳定性,但补偿电容与风电机组控制装置之间的相互作用可能会引发包括次同步谐振和高频谐振的宽频域谐振稳定性问题。考虑串补、并补两种并网线路类型推导并...风电机组经串、并联补偿并网可以降低线损,并有效提高线路送电功率和系统运行的稳定性,但补偿电容与风电机组控制装置之间的相互作用可能会引发包括次同步谐振和高频谐振的宽频域谐振稳定性问题。考虑串补、并补两种并网线路类型推导并建立了双馈风机并网系统的阻抗模型,利用阻抗法分析风机并网系统宽频域谐振的发生机理提出并设计了一个自适应宽频域谐振抑制器,将其并联连接到公共耦合点(point of common coupling,PCC),通过提取PCC点谐振电压并利用谐波含量限制的方法合成一个阻尼电阻以抑制系统产生的宽频域谐振。最后在MATLAB/Simulink中搭建了风电并网系统等值系统模型,通过时域仿真验证了该自适应宽频域谐振控制器的正确性和有效性。展开更多
The four-coil wireless power transfer(WPT)technology can effectively improve the transfer efficiency.The high efficiency,however,cannot be obtained along the whole transfer distance due to the phenomenon of frequency ...The four-coil wireless power transfer(WPT)technology can effectively improve the transfer efficiency.The high efficiency,however,cannot be obtained along the whole transfer distance due to the phenomenon of frequency splitting in the over coupled region.Aiming at this limitation,this paper presents a switchable WPT system to improve the overall efficiency by changing the number of working coils.The switching conditions for the designed system are determined based on the analysis of the transfer efficiencies of four structures,which is deduced through modeling the equivalent circuits.The simulation results well comply with the experimental results and both of them indicate that the switchable system can greatly improve the overall transfer efficiency along the whole transfer distance.The overall efficiency of the experimental system can reach above 70%at9.97 MHz without additional complexity,which is higher than any single structure system.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 51377185
文摘Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer （MR-WPT） system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic performance in engineering. In this study, the shielding effectiveness of a two-coil MR-WPT system for different material shields is analyzed in theory using Moser＇s formula and Schelkunoff＇s formula. On this basis a candidate magnetic-shielding scheme with a double-layer structure is determined, which has better shielding effectiveness and coils coupling coefficient. Finally, some finite element simulation results validate the correctness of the theoretical analysis, and the shielding effectiveness with the double-layer shield in maximum is 30？dB larger than the one with the single-layer case.
基金Project(61104088)supported by the National Natural Science Foundation of ChinaProject(12C0741)supported by Scientific Research Fund of Hunan Provincial Education Department,China
文摘The equivalent two-port network model of a middle range wireless power transfer(WPT) system was presented based on strongly coupled multiple resonators. The key parameters of the WPT system include self-inductance, resistance, parasitic capacitance, mutual inductance and S-parameters of coils & resonators were analyzed. The impedance matching method was used to optimize load power and transmission efficiency of the multi-resonator WPT system, and the impedance matching method was realized through adjusting the distances between the coils and resonators. Experiments show that the impedance matching method can effectively improve load power and transmission efficiency for middle range wireless power transfer systems with multiple resonators, at distances up to 3 times the coil radius with efficiency more than 70% and load power also close to 3.5 W.
基金Human Provincial Natural Science Foudation of China(No.2016JJ4043)Youth Foundation of Education Bureau of Hunan Province,China(No.16B137)Science and Technology Projects of Loudi City,China
文摘The optimization method by adjusting load and distances between two adjacent coils( or resonators) is presented on basis of wireless power transfer( WPT) system with relay resonators. 2-port network and impedance matching theory are applied to analyzing power flow of incidence and reflection in WPT system,then setting up power flow model. The maximum power transmission efficiency can be obtained when the load and distance between secondary resonator and output coil meets impedance matching at 2-port network's output port. The simulation and experimental results shown the impedance matching method can effectively improve and maintain transmission efficiency by adjusting load and distances between coils or relay resonators.
文摘针对谐振式无线电能传输系统中分数阶电感、电容元件的仿真实现困难的问题,采用等效阻抗实现分数阶电容的等效.基于分数阶电容的阻抗特性,给出了一种分数阶RLC_(α)串联谐振双向无线电能传输(bidirectional wireless power transfer,BD-WPT)系统结构,通过建立含分数阶电容的串联谐振式双向无线电能传输系统的电路模型,推导了其传输功率和效率关系.仿真实验结果表明,与整数阶串联谐振系统相比,系统的输出功率提升了7.82%,传输效率提升了0.58个百分点.
文摘风电机组经串、并联补偿并网可以降低线损,并有效提高线路送电功率和系统运行的稳定性,但补偿电容与风电机组控制装置之间的相互作用可能会引发包括次同步谐振和高频谐振的宽频域谐振稳定性问题。考虑串补、并补两种并网线路类型推导并建立了双馈风机并网系统的阻抗模型,利用阻抗法分析风机并网系统宽频域谐振的发生机理提出并设计了一个自适应宽频域谐振抑制器,将其并联连接到公共耦合点(point of common coupling,PCC),通过提取PCC点谐振电压并利用谐波含量限制的方法合成一个阻尼电阻以抑制系统产生的宽频域谐振。最后在MATLAB/Simulink中搭建了风电并网系统等值系统模型,通过时域仿真验证了该自适应宽频域谐振控制器的正确性和有效性。
基金supported by the National Natural Science Foundation of China(Grant No.61473281)the Self-planned Project Funded by State Key Laboratory(Grant No.2013-Z10)
文摘The four-coil wireless power transfer(WPT)technology can effectively improve the transfer efficiency.The high efficiency,however,cannot be obtained along the whole transfer distance due to the phenomenon of frequency splitting in the over coupled region.Aiming at this limitation,this paper presents a switchable WPT system to improve the overall efficiency by changing the number of working coils.The switching conditions for the designed system are determined based on the analysis of the transfer efficiencies of four structures,which is deduced through modeling the equivalent circuits.The simulation results well comply with the experimental results and both of them indicate that the switchable system can greatly improve the overall transfer efficiency along the whole transfer distance.The overall efficiency of the experimental system can reach above 70%at9.97 MHz without additional complexity,which is higher than any single structure system.
