基于耦合电感消除占空比丢失的模块型全桥光伏变换器

摘要

在模块型光伏变换器中,将耦合电感引入到变换器的移相全桥电路的倍压整流侧.在DC/DC级,先分析了耦合电感的数学模型,以及引入耦合电感后变换器的开关模态.重点分析了耦合电感对循环电流的影响,即耦合电感不仅通过耦合作用快速消减原边循环电流进而减少占空比丢失,还能保证DC/DC级移相全桥电路倍压整流侧输出的经SPWM环节调制的工频正弦半波电压的滤波效果,并能实现移相全桥电路超前臂零电压开关.在DC/AC级,经工频逆变桥输出交流电.最后,通过120 W实验样机验证了引入耦合电感后变换器的功能特性,变换器控制简单,并能有效减少占空比丢失引起的谐波含量,进而保证输出电能质量.%The coupled inductors are introduced to the voltage doubler of PSFB(Phase Shift Full Bridge) circuit in modular PV converter. The mathematical model of coupled inductors in DC/DC stage and the switching modes of converter with coupled inductors are analyzed. The influence of coupled inductors on circulating current is detailed;the primary-side circulating current is quickly decreased and the duty cycle loss is thus reduced;the high-quality semiwave sinusoidal voltage output at the rectifier side of voltage doubler in DC/DC stage is guaranteed,which is modulated by SPWM;the ZVS of PSFB leading leg is achieved. The AC output is achieved by the full-bridge inverter in DC/AC stage. The experimental results of a 120 W prototype converter demonstrate the performances of converter with coupled inductors; the control is simple,the harmonic contents caused by the duty cycle loss are reduced and the power quality of converter output is guaranteed.