一种新型耦合电感式双Boost光伏微逆变器拓扑分析

A Novel Topology Analysis of Photovoltaic Micro-inverters with Coupled Inductors and Double Boost

基于光伏发电微逆变器模块,提出了一种耦合电感式双Boost逆变器(CIDBI)电路拓扑。详细分析了它的工作原理,推导了直流到交流的变压比公式,并给出了控制方法。这种逆变器通过占空比和耦合电感的匝数比的设置,可输出幅值远高于直流输入电压值的交流电。文中首先研究了CIDBI电路在一驱动时序下的工作原理,再分析了开关器件的电压应力和输入输出的关系,同时指出了在一定的占空比变化范围内,升压比是随占空比近似线性变化的,相应地应用正弦脉宽调制(SPWM)方式实现了正弦输出。最后,将CIDBI电路应用于光伏发电模块中,分析了该电路的共模电流。实验表明:所提出的CIDBI电路能有效实现低压光伏组件一级式并网发电,无需工频变压器升压和传统的DC/DC升压环节,变换效率高,并网电流总谐波含量低。

A topology of coupled inductor double boost inverter（CIDBI） is proposed based on the photovoltaic micro-inverter module system.The operation principle and control strategy of CIDBI are analyzed in detail and the gain expression from DC side to AC side is deduced.It can generate an AC output voltage much larger than the DC input one,depending on the proper setup of instantaneous duty cycle and turn ratio of the coupled inductors.Firstly,based on a given driving signal series,the operational principle of CIDBI is discussed.Secondly,the voltage stress of switches in CIDBI and the relationship between input and output are analyzed.The gain is approximately proportional to the duty cycle when the duty cycle is around 0.5 and the sinusoidal pulse width modulation（SPWM） is applicable to this novel inverter.Finally,the proposed CIDBI serves as a grid-connected inverter in a photovoltaic generation system.Experimental results show that the CIDBI can competently implement the single-stage grid-connected generation of photovoltaic system with a low level total harmonic distortion of current and high efficiency,without traditional transformer and DC/DC converter.