摘要
针对前级高频DC/DC变换电路的高开关频率和高损耗问题,本文提出了一种更高效的不固定直流母线电压分段控制策略。该策略通过判断直流侧输入电压与交流侧输出电压的关系来控制DC/DC变换电路的工作模式,从而减少同一时间内高频状态下的功率控制开关的数量和时间。为降低非隔离型电路系统的电流谐波,在不固定直流母线电压分段控制策略的基础上,改进了后级逆变电路的拓扑结构,提出了在升压电感支路串联虚拟电阻和直流母线电容支路并联虚拟电阻的新型DC/DC电流前馈控制方法。该方法可利用传递函数等效变换原理结合电路系统幅频特性得出最优的虚拟电阻值,能很好地抑制直流侧谐波,优化并网电流的总谐波含量(THD)。通过仿真和实验结果表明,本文所提出的控制策略能提高并网逆变器的功率转换效率,并可以抑制直流母线电流的二次谐波。
In view of the high switching frequency and high loss of the front-stage high frequency DC/DC converter circuit,this paper proposes a more efficient unfixed DC bus voltage section control strategy.This strategy controls the working modes of DC/DC converter circuit by judging the relationship between the input voltage on the DC side and the output voltage on the AC side,thereby reducing the number of power control switches and time that work in a high frequency state in the same time.In order to reduce the current harmonic of the non-isolated circuit system,based on the section control strategy of unfixed DC bus voltage,the topological structure of the back-stage inverter circuit is improved.A novel DC/DC current feedforward control method is proposed in which series virtual resistance of boost inductance branch and parallel virtual resistance of DC bus capacitance branch.Using the transfer function equivalent transformation principle and the circuit system amplitude-frequency characteristics to obtain the optimal virtual resistance value,it can well suppress the DC side harmonics and optimize the total harmonic content(THD)of the grid-connected current.Simulation and experimental results show that the proposed control strategy can improve the power conversion efficiency of the grid-connected inverter and suppress the second harmonic of DC bus current.
作者
刘偲艳
Liu Siyan(Photovoltaic System Control and Optimization of Hunan Province Engineering Laboratory,Xiangtan 411104,China)
出处
《太阳能》
2021年第11期75-82,共8页
Solar Energy
基金
湖南省教育厅科学研究项目(19C0873)。
