光伏逆变器电流畸变的自适应抑制设计研究

Research on adaptive suppression design of current distortion in photovoltaic inverter

借助新型的开关支路低频调制的方式可以有效降低光伏逆变器的开关损耗,但会导致输出电流总谐波失真度(THD)的增大,从而恶化逆变器的输出性能。为此,提出了一种光伏逆变器的自适应电流畸变抑制调制策略,仅在过零点时使用传统高频脉宽调制(PWM),而在其他区段自适应切换至降损开关支路低频PWM调制,从而在降低光伏逆变器开关损耗的同时实现低THD的输出效果。以T型逆变拓扑为例,介绍了两种PWM调制策略的工作原理,对提出的光伏逆变器的自适应电流畸变抑制调制策略进行了分析,通过仿真和样机实验对所提出的自适应电流畸变抑制调制策略进行验证。实验结果表明所提出的方案可以获得低开关损耗,同时有效抑制光伏逆变器的输出电流畸变。

With the help of the low-frequency modulation method of new switching branch,the switching loss of photovoltaic inverter can be effectively reduced,but it would increase the total harmonic distortion THD of output current,which would deteriorate the output performance of the inverter.Therefore,an adaptive suppression modulation strategy of current distortion for photovoltaic inverter was proposed,only using the traditional highfrequency PWM modulation when crossing the zero point,and adaptively switching to the low-frequency PWM modulation of loss reducing switching branch in other sections,so as to achieve the output effect of low THD while reducing the switching loss of photovoltaic inverter.Taking the T-type inverter topology as an example,the working principles of two PWM modulation strategies were introduced,the proposed adaptive current distortion suppression modulation strategy was analyzed,and the strategy was verified through simulation and prototype experiments.The results show that the proposed scheme can achieve low switching loss and effectively suppress the output current distortion of photovoltaic inverter.