高调制深度下三电平NPC逆变器中点电位快速均衡控制

Proposes an optimized virtual space vector PWM algorithm enabling fast and full-range neutral-point voltage balancing across the entire linear modulation region, even with asymmetric DC-link capacitors. Features fuzzy-based closed-loop control and coordinate simplification, reducing computational burden. Experimental results show neutral-point deviation <1.14% and lower grid-current THD vs. conventional VSVPWM.

针对常规虚拟空间矢量脉宽调制VSVPWM(virtual space vector pulse-width modulation)在高调制深度下,母线中点电位存在不可控区域问题,提出1种可在整个线性调制区实现中点电位快速均衡的优化型VSVPWM算法.基于VSVPWM母线中点电位均衡原理重构虚拟中矢量,为保证重构后虚拟中矢量的均压性能,同时提高算法对系统参数摄动的适应性,设计用于中点电压闭环控制的模糊推理确定重构因子对VSVPWM进行优化.即使在直流母线电容不对称情况下,优化型VSVPWM仍可实现线性调制区全范围的快速均压控制.进一步在60°坐标系内对算法简化,参考电压矢量子区域的判断条件、伏秒平衡方程组从30个减少至5个.实验结果表明,该控制策略具有良好性能,均压调节时间显著降低,直流母线中点电位稳态偏差可控制在1.14％内,相较于传统VSVPWM,并网电流总谐波含量更低.