摘要
对于三电平控制的并网逆变器,采用变环宽的数字化滞环控制器能在大部分时间稳定开关频率,但在电压过零点附近仍然存在开关频率波动的现象。这主要是由于模数变换器采样频率的限制,导致电流在变化过程中,并不能准确地捕捉到滞环控制器的边界,并且由于电压过零点附近滞环控制器的环宽趋近于零,开关频率的波动将进一步恶化。为稳定开关频率,这里提出了混合电平控制策略改进电压过零点附近的开关频率波动。在电压过零点附近,将逆变器由三电平工作状态切换为两电平工作状态,从而增大了滞环比较器的环宽,稳定了滞环控制并网逆变器的开关频率,提高了并网逆变器的电能质量。
For a grid-tied three-level inverter,fully digital hysteresis controller with variable band can stabilize the switching frequency most of the time,but the switching frequency fluctuation near the voltage zero crossing point.The challenge mainly comes from the restriction of analogue-to-digital converter sampling frequency,which leads to boundary of hysteresis controller can not be accurately captured in the process of current change.Moreover,since the width of the hysteresis controller near the voltage zero crossing point approaches zero,the switching frequency fluctuation will further deteriorate.In order to stabilize the switching frequency,a mixed-level scheme is proposed to cope with the switching frequency fluctuation near the voltage zero crossing point.It switches operating status from three-level state into two-level state around voltage zero crossing point to enlarge the band of the hysteresis controller,stablize the switching frequency of hysteresis controlled grid-tied inverter,and increase the power quality of the grid-tied inverter.
作者
周文
曾四鸣
杨少波
胡雪凯
ZHOU Wen;ZENG Si-ming;YANG Shao-bo;HU Xue-kai(State Grid Hebei Electric Power Research Institude,Shijiazhuang 073000,China)
出处
《电力电子技术》
CSCD
北大核心
2021年第8期102-106,共5页
Power Electronics
基金
河北省重点研发计划(19212102D)。
关键词
逆变器
混合电平
滞环控制
开关频率波动
inverter
mixed-level
hysteresis controlled
switching frequency fluctuation
