The multi-string LED in parallel is a popular structure in backlight and lighting applications.The current balancing for each string is required to achieve uniform luminance and reliable operation.The conventional act...The multi-string LED in parallel is a popular structure in backlight and lighting applications.The current balancing for each string is required to achieve uniform luminance and reliable operation.The conventional active current sharing technique using a switching converter or a linear switch is very complex,and needs extra components.The conventional coupled inductor based current sharing method is much more simple,but needs too many coupled inductors.展开更多
Cable-in-conduit conductor （CICC） conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor sample exhibited a stable performance regarding the cu...Cable-in-conduit conductor （CICC） conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor sample exhibited a stable performance regarding the current sharing temperature. Under the typical operational conditions of a current of 45 kA, a magnetic field of 4 T and a temperature of 5 K for PF2, the test result for the conductor current sharing temperature is 6.71 K, with a temperature margin of 1.71 K. For a comparison thermal-hydraulic analysis of the PF2 conductor was carried out using GANDALF code in a 1-D model, and the result is consistent with the test one.展开更多
A bridge arm prototype of ITER poloidal field （PF） converter modules has been designed and fabricated. Non-cophase counter parallel connection is chosen as the arm structure of the prototype. Among all factors affec...A bridge arm prototype of ITER poloidal field （PF） converter modules has been designed and fabricated. Non-cophase counter parallel connection is chosen as the arm structure of the prototype. Among all factors affecting current sharing, arm structure is the main one. During the design of the arm prototype, a novel method based on inductance matrixes is employed to improve the current sharing of the bridge arm. The test results on the prototype show that the current sharing performance of the arm prototype is much better than relevant design requirement, and that the matrix method is very effective to analyze and solve the current sharing problems of thyristor converters.展开更多
In response to the current imbalance phenomenon and its harmfulness, a current sharing circuit model is built up, which reveals the underlying causes for the current imbalance through a quantitative analysis. Then, a ...In response to the current imbalance phenomenon and its harmfulness, a current sharing circuit model is built up, which reveals the underlying causes for the current imbalance through a quantitative analysis. Then, a feasible approach of improvement, namely enlargement of the length of connection busbars, is proposed. After the amendment, it can be seen that the current sharing coefficient is ahnost unity under rated or fault current conditions.展开更多
The superconducting toroidal field （TF） plays an important role in a superconducting tokamak, whose power supply was developed based on the feedback control principle. In this paper, superconducting tokamaks in diff...The superconducting toroidal field （TF） plays an important role in a superconducting tokamak, whose power supply was developed based on the feedback control principle. In this paper, superconducting tokamaks in different countries are described, and the TF power supply of the International Thermonuclear Experimental Reactor （ITER） is taken as an example to study the current-sharing characteristics in the current-stabilized stage. Firstly, the mathematical model of the TF power supply is established, and then the 3-loop control method is put forward for achieving the stability and reliability of current-stabilization and current-sharing. Furthermore, further studies indicate that the current-sharing controller has no influence on the current-stabilized control, and current-stabilizing and current-sharing can be realized at the same time. All the work done provides valuable references for the current-sharing design of the TF power supply for a superconducting tokamak, and all these studies lay a solid foundation for developing superconducting tokamaks.展开更多
在光储孤岛直流微电网中,需要最大化利用光伏发电,通常对光伏系统采用最大功率点跟踪(maximum power point tracking, MPPT)技术。但传统的MPPT控制速度慢、精度低,特别是在局部阴影情形下极易陷入局部最优解。基于此,首先提出一种将布...在光储孤岛直流微电网中,需要最大化利用光伏发电,通常对光伏系统采用最大功率点跟踪(maximum power point tracking, MPPT)技术。但传统的MPPT控制速度慢、精度低,特别是在局部阴影情形下极易陷入局部最优解。基于此,首先提出一种将布谷鸟搜索算法与电导增量法相结合的混合MPPT控制。利用布谷鸟搜索算法快速全局寻优,再使用电导增量法精确定位,实现快速而准确地跟踪最大功率点。储能单元是光储直流微电网的重要组成部分,其输出电流均分、荷电状态(stateof charge, SoC)均衡和直流母线电压稳定是主要控制目标。但电流均分受线路电阻差异的影响,进而影响SoC均衡和直流母线电压稳定,于是设计一种新的电压电流双环控制策略以实现上述目标。该策略在电压外环采用母线电压作为反馈值,在电流内环中设计了基于一致性算法的控制策略,将SoC与指数函数结合并引入加速因子,使得在充放电过程中实现SoC的快速均衡。所提控制策略既不需要下垂控制,也无需二次补偿控制,减轻了通信负担。最后在Matlab/Simulink中搭建直流微电网系统模型,验证所设计新的混合MPPT控制和电压电流双环控制策略的有效性。展开更多
In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power...In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power supply module in a UPS, it would be better to reduce the output current ratio for a hotter supply module in the UPS. In this design, we implemented our regulation circuits by the UMC 0.25-μm CMOS technology with an input range from 3 V to 4.2 V and the regulated output at 1.1 V. The rated output current was 100 mA for each phase. We also employed a current-mode error-correction circuit to improve the current sharing performance based on the averaged current of each phase at the same temperature. According to our simulation results, the current sharing error can be restricted within ± 5% for the supply modules at the same temperature in our system.展开更多
文摘The multi-string LED in parallel is a popular structure in backlight and lighting applications.The current balancing for each string is required to achieve uniform luminance and reliable operation.The conventional active current sharing technique using a switching converter or a linear switch is very complex,and needs extra components.The conventional coupled inductor based current sharing method is much more simple,but needs too many coupled inductors.
基金supported by the Priority Base Research Development Project of China (No. 0559730532)
文摘Cable-in-conduit conductor （CICC） conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor sample exhibited a stable performance regarding the current sharing temperature. Under the typical operational conditions of a current of 45 kA, a magnetic field of 4 T and a temperature of 5 K for PF2, the test result for the conductor current sharing temperature is 6.71 K, with a temperature margin of 1.71 K. For a comparison thermal-hydraulic analysis of the PF2 conductor was carried out using GANDALF code in a 1-D model, and the result is consistent with the test one.
文摘A bridge arm prototype of ITER poloidal field （PF） converter modules has been designed and fabricated. Non-cophase counter parallel connection is chosen as the arm structure of the prototype. Among all factors affecting current sharing, arm structure is the main one. During the design of the arm prototype, a novel method based on inductance matrixes is employed to improve the current sharing of the bridge arm. The test results on the prototype show that the current sharing performance of the arm prototype is much better than relevant design requirement, and that the matrix method is very effective to analyze and solve the current sharing problems of thyristor converters.
文摘In response to the current imbalance phenomenon and its harmfulness, a current sharing circuit model is built up, which reveals the underlying causes for the current imbalance through a quantitative analysis. Then, a feasible approach of improvement, namely enlargement of the length of connection busbars, is proposed. After the amendment, it can be seen that the current sharing coefficient is ahnost unity under rated or fault current conditions.
基金supported by the National Basic Research Program of China(973Program)(No.2007ID200)the Special Fund of Talent Development of Anhui Province(No.2009Z056)the Research Fund for the Doctoral Program of Anhui University of Architecture(No.K02425)
文摘The superconducting toroidal field （TF） plays an important role in a superconducting tokamak, whose power supply was developed based on the feedback control principle. In this paper, superconducting tokamaks in different countries are described, and the TF power supply of the International Thermonuclear Experimental Reactor （ITER） is taken as an example to study the current-sharing characteristics in the current-stabilized stage. Firstly, the mathematical model of the TF power supply is established, and then the 3-loop control method is put forward for achieving the stability and reliability of current-stabilization and current-sharing. Furthermore, further studies indicate that the current-sharing controller has no influence on the current-stabilized control, and current-stabilizing and current-sharing can be realized at the same time. All the work done provides valuable references for the current-sharing design of the TF power supply for a superconducting tokamak, and all these studies lay a solid foundation for developing superconducting tokamaks.
文摘在光储孤岛直流微电网中,需要最大化利用光伏发电,通常对光伏系统采用最大功率点跟踪(maximum power point tracking, MPPT)技术。但传统的MPPT控制速度慢、精度低,特别是在局部阴影情形下极易陷入局部最优解。基于此,首先提出一种将布谷鸟搜索算法与电导增量法相结合的混合MPPT控制。利用布谷鸟搜索算法快速全局寻优,再使用电导增量法精确定位,实现快速而准确地跟踪最大功率点。储能单元是光储直流微电网的重要组成部分,其输出电流均分、荷电状态(stateof charge, SoC)均衡和直流母线电压稳定是主要控制目标。但电流均分受线路电阻差异的影响,进而影响SoC均衡和直流母线电压稳定,于是设计一种新的电压电流双环控制策略以实现上述目标。该策略在电压外环采用母线电压作为反馈值,在电流内环中设计了基于一致性算法的控制策略,将SoC与指数函数结合并引入加速因子,使得在充放电过程中实现SoC的快速均衡。所提控制策略既不需要下垂控制,也无需二次补偿控制,减轻了通信负担。最后在Matlab/Simulink中搭建直流微电网系统模型,验证所设计新的混合MPPT控制和电压电流双环控制策略的有效性。
文摘In this study, a temperature-based current sharing strategy rather than equal sharing for loads was applied to promote the reliability of uninterruptible power systems (UPS). According to the temperature of each power supply module in a UPS, it would be better to reduce the output current ratio for a hotter supply module in the UPS. In this design, we implemented our regulation circuits by the UMC 0.25-μm CMOS technology with an input range from 3 V to 4.2 V and the regulated output at 1.1 V. The rated output current was 100 mA for each phase. We also employed a current-mode error-correction circuit to improve the current sharing performance based on the averaged current of each phase at the same temperature. According to our simulation results, the current sharing error can be restricted within ± 5% for the supply modules at the same temperature in our system.
