基于GaN器件的双Buck逆变器共模与损耗

目前市场上的光伏并网逆变器结构按隔离方式来分,可分为隔离型和非隔离型,而抑制或消除共模电流是非隔离型光伏并网系统必须要解决的问题。出于在非隔离型光伏并网逆变器中抑制共模电流的目的,研制一种基于GaN器件的双Buck逆变器,该逆变器较传统全桥电路,共模电流小、效率高、控制简单。针对共模特性进行分析研究,分别对其在正常工况与死区状态的共模电流进行理论分析,并进行仿真与实验验证,得出该逆变器能够很好地抑制共模电流的结论。通过引入GaN器件来提高开关频率解决拓扑自身电感较大这一问题,并基于GaN器件对电路进行损耗分析与实验验证,实验结果与理论分析基本吻合,验证了损耗分析的正确性。该逆变器的实测最高效率高达98.63%。

The Common-Mode Characteristics and Loss of Dual Buck Grid-Connected Inverter Based on GaN Devices

Currently, photovoltaic (PV) grid inverters can be divided into isolated type and non-isolated type inverters. Restraining or eliminating CM current of the isolated PV grid inverters is a problem that must be solved. This paper developed a dual Buck inverter based on Gallium Nitride (GaN) devices to suppress the CM current in PV grid inverter. Compared with traditional full bridge converter, this inverter has small CM current and high efficiency. This paper analyzed its CM characteristics in normal working and dead band conditions respectively. The simulations and experiments were used to verify the theory. At the same time, this paper used GaN devices to improve frequency to reduce the size of inductor, and analyzed the loss of dual Buck inverter based on the GaN device, which matches the experiment very well. The maximum efficiency of the inverter is 98.63%.