基于激活函数的LCC-S型无线电能传输系统建模和稳定性分析  

Modeling and Stability Analysis of Wireless Power Transfer System with an LCC-S Compensated Network Based on Activation Function

作　　者：胡秀芳 王跃[1] 吕双庆 赵德林 马天录 Hu Xiufang;Wang Yue;Lü Shuangqing;Zhao Delin;Ma Tianlu(State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]电力设备电气绝缘国家重点实验室(西安交通大学),西安710049

出　　处：《电工技术学报》2023年第6期1553-1563,共11页Transactions of China Electrotechnical Society

摘　　要：基于电力电子器件的无线电能传输(WPT)系统是一种开关系统,其大信号模型是研究系统运行特性和稳定性的基础。建模的关键是如何描述系统中的非线性、离散开关变量,为解决这一问题,该文提出一种基于S型激活函数的建模方法。S型激活函数是连续、平滑、可微的且在一定值时具有饱和特性,因此可利用陡度因子较大的激活函数来近似开关的切换过程,将WPT系统由离散的开关系统转变为连续系统。该文以LCC-S型WPT系统为研究对象,构建其开环和闭环模式下激活函数模型,利用该模型分析控制器参数和系统参数对瞬态行为和稳定性的影响,并通过仿真和实验进行验证。结果表明,所构建的模型与仿真和实验结果吻合较好。该模型数学表达式结构简单统一,物理意义明确,是一个具有普遍意义的高精度大信号连续模型。Wireless power transfer(WPT)system based on power electronic devices is a switching system,its large-signal model is the basis for studying the operating characteristics and stability of the system.The key to modeling is how to describe the nonlinear and discrete switch variables in the system.In this paper,a modeling method based on sigmoid activation function is proposed to solve this problem.Since the sigmoid activation function is continuous,smooth,differentiable,and saturated at a certain value.Therefore,a sigmoid activation function with a large steepness factor is used to approximate the switching process of the switch,the WPT system is transformed from a discrete switching system to a continuous system.An LCC-S compensated WPT system is selected as an example,and its sigmoid function model in open-loop and closed-loop mode is constructed.However,in closed-loop control mode,the time delay in digital control system is often ignored.Delay link makes WPT system more complicated.For systems without time delay,a certain mapping relationship can be established between input and output.But the existence of time delay may disturb this specific relationship.For the same sampled signal,the time delay in digital control system may lead to the instability of WPT system.The performance of WPT system will inevitably be affected or even deteriorated.Therefore,it is necessary to analyze the stability considering the influence of time delay.In order to avoid these problems,approximating the time delay in stability analysis becomes a preferred solution.Time delay can be approximated by first-order lag,Taylor expansion,Pade approximation,etc.Compared with the first-order lag and Taylor series,Pade approximation has better performance because of its rational polynomial form.In addition,Pade approximation can handle a relatively short delay.Because the time delay of digital control system is in the order of microseconds,Pade approximation may be more appropriate.Based on the fifth-order pade equivalent approximate delay link,a

关 键 词：无线电能传输系统 LCC-S 补偿 激活函数 大信号模型 稳定性 

分 类 号：TM724[电气工程—电力系统及自动化]