超级电容串联储能系统的并联电容均压方法

针对现有超级电容串联模组均压电路对A/D采样电路精度要求高,均压速度受串联电容数量影响大的瓶颈问题,该文提出一种超级电容串联模组并联电容均压方法,包括通过开关与电感级联的并联电容均压电路和开关控制方法。该文基于离散时域法对储能系统状态向量进行了分析,验证了该均压电路的均压特性。应用时域仿真验证了计算结果。通过静置仿真试验验证4支电容均压时间与2支电容均压时间相同。最后该文进行了物理试验,设计了试验样机。理论分析、仿真和物理试验结果验证了该方法在超级电容模组静置、充电、放电工况下都具有均压作用,均压过程无需调用采样电路数据既可实现电压均衡,均压速度受串联电容数量影响小。     

基于叉指结构的平面分形电容研究

以基于叉指结构的平面分形电容为研究对象,电容由激光刻蚀法制得,在测得其S参数后,利用ADS仿真工具进行了一阶等效电路参数提取及分析.结果表明,随着共面叉指电极间距的相对减小,电极间的耦合增大,相应的寄生电感也增大;而分形设计可以在保证电极间距不变的情况下,改善电容的工作稳定性.最后制得的分形平面电容的电容值在1~7 pF之间,电容稳定工作频率可达2.5 GHz以上,显示了较好的可调性和稳定性.     

超级电容动态容值测量与容值函数参数估计

针对目前的超级电容参数在线识别方法动态参数测量困难,通用性差,精度低的缺点,提出一种超级电容动态容值测量与参数识别方法。该方法中提出了动态电容值测量模型,通过电荷关系式与能量关系式联立推导动态电容值测量方程组,并采用限定记忆最小二乘法进行参数识别,应用时域仿真对该方法进行了验证。仿真结果表明,该文提出的电容值测量与参数识别方法适用于多种不同的容值函数。当测量信号存在噪声时仍可对电容测量,平均误差低于1%,参数估计相对误差低于20%,可以应用于超级电容动态容值测量。     

开关电感型Z源逆变器拓扑结构的设计与仿真

该文在开关电感型Z源逆变器的基础上提出一种高电压增益的开关电感型Z源逆变器。与传统的开关电感型Z源逆变器相比,新型拓扑不仅保留了X型的基本结构,而且将二极管和逆变桥的位置互换,同时增加了2个电感和6个二极管,这样可以减小电容电压应力,增大直流链路峰值电压,使输入电流具有连续性;另外,新型拓扑的控制方法简单,采用直接升压控制方法,它以正弦波为调制波、三角波为载波,是一种基于正弦脉宽调制控制技术的一种控制方法。在理论分析的基础上,对新型拓扑进行仿真试验,结果表明：当直通占空比为0.139、调制系数为0.85时,新型拓扑直流链路峰值电压为127.95 V,电容电压应力为39.50 V,而传统拓扑的直流链路峰值电压为89.65 V,电容电压应力为68.40 V,新型拓扑在获得较大直流链路峰值电压的同时,可以保证电容上承受的电压应力较小。通过仿真试验,验证了新型拓扑的优点。     

An asymmetric fault ride-through control method forPMSG wind turbine based onsuper-capacitors

With the rapid increasing interaction between wind turbines and power systems, wind turbines have to have the fault ride-through (FRT) capability to ensure the safe operation of power grid. In order to improve the asymmetric FRT capability of permanent magnet synchronous generator (PMSG) wind turbine, a novel control FRT method based on super-capacitors is proposed. In this method, super-capacitors are connected to the DC bus of AC-DC-AC converter via a bi-directional DC-DC converter, and the power processed by the super-capacitors is controlled to limit the increasing of the DC bus voltage of the AC-DC-AC converter in grid failure condition, and to reduce the 2nd order voltage ripple in the DC bus. Meanwhile, the proposed control method employs the grid voltage feed-forward approach to reduce the negative sequence current component in the grid side converter. According to the low voltage ride through (LVRT) standard, the selection of the super-capacitor capacity is also discussed, and then a mathematical model of the super-capacitor with the bi-directional DC-DC converter is established for designing the controller. Simulation results for a 1MW PMSG wind turbine by MATLAB show that the proposed control method reduces both the negative sequence current component in grid side converter and the 2nd order voltage ripple in DC link at the same time. The results also demonstrate that the asymmetric FRT capability of PMSG wind turbine is improved, which verifies the effectiveness of the proposed control method in this paper.