一种单相H桥光伏逆变器混沌控制方法

A chaos control method of single-phase H-bridge photovoltaic inverter

比例积分调节单相H桥光伏逆变器存在复杂的分岔与混沌等非线性行为,这些非线性行为会大大增加输出电流的谐波含量,降低系统运行的稳定性与供电可靠性.现有的混沌控制方法存在建模复杂、控制系数难以确定等问题.针对于此,本文提出了一种改进指数延迟反馈控制方法.该方法首先利用系统输出电流与其自身延迟的差值形成反馈信号,然后将该反馈信号通过指数环节、作差环节和比例环节得到控制信号,并将该控制信号以反馈的形式施加于被控系统,同时建立系统的离散映射模型并求取系统雅克比矩阵表达式;最后基于稳定判据推导出该控制信号的反馈控制系数的限定条件并实施对系统的控制.为了验证该方法的控制效果,进行了大量的仿真实验.结果表明,该方法能有效抑制系统中的混沌行为,大大扩展系统稳定运行域.

There are complex nonlinear behaviors such as bifurcation and chaos in a single-phase H-bridge photovoltaic inverter under proportional integral control,which will increase the harmonic content of the output current greatly and reduce the stability of system operation and reliability of power supply.There are the problems suffering the complicated modeling and difficulty in determining the control coefficients in existing chaos control methods.The exponential delay feedback control is a further development of the delay feedback control,which has the advantages of requiring no precise mathematical model of the system and simple implementation.However,our research shows that when the exponential delay feedback control is directly applied to the system,the feedback intensity cannot be controlled,which will bring too big a disturbance to the system.Based on it,an improved exponential delayed feedback control method is proposed in this paper.Firstly,a feedback signal is formed by the difference between the output current of the system and its own delay,then the feedback signal is used to obtain the control signal through an exponential link,a subtraction link and an proportion link,and the control signal is applied to the controlled system in the form of a feedback.At the same time,the discrete mapping model of the system is established and its Jacobian matrix expression is determined.Finally,the limiting conditions of the feedback control coefficient of the control signal are derived based on the stability criterion,and the control is applied to the system.In order to verify the control effect of this method,a lot of simulation experiments are conducted.The results show that the problems that the exponential delay feedback cannot control the feedback strength and causes excessive disturbance to the system will be effectively solved by this method.When the bifurcation parameters vary greatly,the chaos behaviors in the system will be suppressed effectively,the stable operating domain of the system will be expanded greatly and the harmonic content of the output current will be reduced.