With the rapid development of high temperature superconducting(HTS)technology,second generation(2G)HTS materials have become a promising alternative to traditional conductive materials in the power transmission indust...With the rapid development of high temperature superconducting(HTS)technology,second generation(2G)HTS materials have become a promising alternative to traditional conductive materials in the power transmission industry.Recently,the topic of using HTS materials in wireless power transfer(WPT)systems for electric vehicles(EVs)has attracted widespread attention in the background of net zero transport.With virtually zero DC resistance and superior current‐carrying capacity,HTS materials can achieve high quality factor and power density in the WPT resonant circuits compared to conventional metals,e.g.,copper.However,the optimal working frequency for the conventional WPT system is relatively high in the order of kilohertz level.Superconducting coils working at high frequencies could generate high AC losses,reducing the overall power transfer efficiency(PTE)and increasing the cooling burden.In order to improve the PTE of HTS‐WPT systems,the AC loss mitigation methods for different HTS coil topologies have been investigated in this paper by varying the inter‐turn gap and tape width.Three HTS coil structures,namely the spiral coil,the solenoid coil and the double pancake(DP)coil,have been studied with a 2D axisymmetric multi‐layer numerical model based on the H‐formulation,and the simulation results have been validated by the published experimental data.The general loss characteristics,loss distributions in each turn,as well as magnetic flux densities have been analysed in detail for three types of HTS coils.Moreover,the impact of these two loss reduction methods on the WPT performance has also been evaluated.Findings have shown that increasing the inter‐turn gap and tape width can effectively reduce the AC power losses and increase the PTE of the HTS‐WPT system.The spiral coil demonstrates the highest AC power loss reduction effect and PTE while maintaining a stable level of magnetic fields.This paper is believed to deepen the understanding of superconducting WPT and provide a useful reference for more efficient wireless energisation applications.展开更多
The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size limitations.In this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-spar...The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size limitations.In this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-sparse configuration is proposed to achieve a high quality factor(Q-factor)and uniform magnetic field,which ensures high efficiency and improves the misalignment tolerance for several-megahertz WPT systems.Furthermore,a closed-form expression for the Q-factor is provided and analyzed for coil optimization.By using this method,a TX-coil with an outer diameter of 100 mm and a wire diameter of 1.5 mm is designed and tested at 1 MHz.Finite element method simulations and experimental results demonstrate that the Q-factor is increased by about 8%in comparison with evenly spaced planar spiral coils,which is achieved while ensuring a relatively uniform magnetic field.展开更多
针对传统单个逆变器驱动的无线电能传输(wireless power transfer,WPT)系统输出功率有限的问题,提出了一种多逆变器模块并联驱动的大功率WPT系统,并对多逆变器模块并联的拓扑结构和各模块间的环流进行了分析。为了解决逆变器并联时产生...针对传统单个逆变器驱动的无线电能传输(wireless power transfer,WPT)系统输出功率有限的问题,提出了一种多逆变器模块并联驱动的大功率WPT系统,并对多逆变器模块并联的拓扑结构和各模块间的环流进行了分析。为了解决逆变器并联时产生的环流问题,提出了基于主从策略的相位同步控制方法,通过从逆变器输出电压和发送端电流相位差同步于主逆变器输出电压和发送端电流相位差实现逆变器模块间的相位差补偿。研制了三个逆变器模块并联驱动的WPT系统样机,实验结果表明,在500 V直流输入时,负载端获得功率约为20 kW,传输效率达94%,且各逆变器输出电压相位实现同步,证明了相位同步控制方法的有效性。展开更多
为了研究长距离交流输电线路上并联电抗器布置对功率传输的影响,基于长距离超、特高压输电线路分布参数等效电路及二端口模型,分析了传输线路的最大传输功率及最大传输效率,推导了串补条件下两种并联电抗器布置方案的级联传输矩阵。采用...为了研究长距离交流输电线路上并联电抗器布置对功率传输的影响,基于长距离超、特高压输电线路分布参数等效电路及二端口模型,分析了传输线路的最大传输功率及最大传输效率,推导了串补条件下两种并联电抗器布置方案的级联传输矩阵。采用500 k V、1 100 k V线路典型参数,针对并联电抗器布置对最大传输功率与最大传输效率的影响进行数值模拟分析。研究结果表明并联电抗器位置在发送端与中点串补电容之间或者接收端与中点串补电容之间变化时,最大传输功率与最大传输效率均随其位置变化而发生变化。同时,并联电抗器补偿度也会影响功率传输,随着并联电抗器补偿度的增加最大传输功率及最大传输效率均会降低。展开更多
文摘With the rapid development of high temperature superconducting(HTS)technology,second generation(2G)HTS materials have become a promising alternative to traditional conductive materials in the power transmission industry.Recently,the topic of using HTS materials in wireless power transfer(WPT)systems for electric vehicles(EVs)has attracted widespread attention in the background of net zero transport.With virtually zero DC resistance and superior current‐carrying capacity,HTS materials can achieve high quality factor and power density in the WPT resonant circuits compared to conventional metals,e.g.,copper.However,the optimal working frequency for the conventional WPT system is relatively high in the order of kilohertz level.Superconducting coils working at high frequencies could generate high AC losses,reducing the overall power transfer efficiency(PTE)and increasing the cooling burden.In order to improve the PTE of HTS‐WPT systems,the AC loss mitigation methods for different HTS coil topologies have been investigated in this paper by varying the inter‐turn gap and tape width.Three HTS coil structures,namely the spiral coil,the solenoid coil and the double pancake(DP)coil,have been studied with a 2D axisymmetric multi‐layer numerical model based on the H‐formulation,and the simulation results have been validated by the published experimental data.The general loss characteristics,loss distributions in each turn,as well as magnetic flux densities have been analysed in detail for three types of HTS coils.Moreover,the impact of these two loss reduction methods on the WPT performance has also been evaluated.Findings have shown that increasing the inter‐turn gap and tape width can effectively reduce the AC power losses and increase the PTE of the HTS‐WPT system.The spiral coil demonstrates the highest AC power loss reduction effect and PTE while maintaining a stable level of magnetic fields.This paper is believed to deepen the understanding of superconducting WPT and provide a useful reference for more efficient wireless energisation applications.
基金Supported by the Key Program of National Natural Science Foundation of China(51437005).
文摘The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size limitations.In this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-sparse configuration is proposed to achieve a high quality factor(Q-factor)and uniform magnetic field,which ensures high efficiency and improves the misalignment tolerance for several-megahertz WPT systems.Furthermore,a closed-form expression for the Q-factor is provided and analyzed for coil optimization.By using this method,a TX-coil with an outer diameter of 100 mm and a wire diameter of 1.5 mm is designed and tested at 1 MHz.Finite element method simulations and experimental results demonstrate that the Q-factor is increased by about 8%in comparison with evenly spaced planar spiral coils,which is achieved while ensuring a relatively uniform magnetic field.
文摘针对传统单个逆变器驱动的无线电能传输(wireless power transfer,WPT)系统输出功率有限的问题,提出了一种多逆变器模块并联驱动的大功率WPT系统,并对多逆变器模块并联的拓扑结构和各模块间的环流进行了分析。为了解决逆变器并联时产生的环流问题,提出了基于主从策略的相位同步控制方法,通过从逆变器输出电压和发送端电流相位差同步于主逆变器输出电压和发送端电流相位差实现逆变器模块间的相位差补偿。研制了三个逆变器模块并联驱动的WPT系统样机,实验结果表明,在500 V直流输入时,负载端获得功率约为20 kW,传输效率达94%,且各逆变器输出电压相位实现同步,证明了相位同步控制方法的有效性。
文摘为了研究长距离交流输电线路上并联电抗器布置对功率传输的影响,基于长距离超、特高压输电线路分布参数等效电路及二端口模型,分析了传输线路的最大传输功率及最大传输效率,推导了串补条件下两种并联电抗器布置方案的级联传输矩阵。采用500 k V、1 100 k V线路典型参数,针对并联电抗器布置对最大传输功率与最大传输效率的影响进行数值模拟分析。研究结果表明并联电抗器位置在发送端与中点串补电容之间或者接收端与中点串补电容之间变化时,最大传输功率与最大传输效率均随其位置变化而发生变化。同时,并联电抗器补偿度也会影响功率传输,随着并联电抗器补偿度的增加最大传输功率及最大传输效率均会降低。