双频双模并网逆变器拓扑结构及控制方法研究

Research on Topology and Control Method of Dual Frequencies Dual Modes Grid Connected Inverter

为了进一步提高并网电流的质量和并网逆变器的效率,提出一种并联型双频双模单相并网逆变器,其主电路包含低频逆变单元和高频整流单元。为了降低系统的开关损耗,低频逆变单元工作在低开关频率;高频整流单元工作在高开关频率,产生与低频逆变单元谐波电流相反的电流。并网电流为逆变单元电流和整流单元电流之和,用高频整流单元的电流抵消掉低频逆变单元的电流后,理论上并网电流等于逆变电流的基波分量,有效地提高了并网电流质量。在介绍新型单相并网逆变器的拓扑结构和工作原理的基础上,给出并网逆变器的控制策略,整个控制系统包括一个逆变电流环和一个整流双闭环。实验结果验证了理论分析的正确性。

In order to improve the quality of grid connected eurrent and the efficiency of grid connected inverter,a dual frequencies dual modes single phase grid connected inverter is proposed.The main circuit of dual frequencies dual modes single phase grid connected inverter includes low frequency inverter unit and high frequency rectifier unit. In order to reduce switch losses of power devices,the inverter unit operates at low switch frequency when the rectifier unit operates at high switch frequency.The high frequency rectifier unit produces a current which is opposite to the low frequency inverter unit harmonic current.Equaling to the fundamental component of low frequency current,the grid connected current is the sum of the inverter unit current and the rectifier unit current which effectively suppress the harmonics in the grid connected current.The control strategy of the single phase grid connected inverter is given based on introducing the topology structure and working principle of dual frequencies dual modes single phase grid connected inverter.The control system contains a current loop of inverter unit and a double-loop of rectifier,which realize the control of grid current.The experimental results verify the correctness of the theoretical analysis.