二极管箝位三电平逆变器共模电压抑制技术

摘要

Small vectors are divided into positive small vectors and negative small vectors based on the direction of phase current and neutral current,and a novel NPSVPWM(No-Positive Small Vectors Pulse Width Modulation) strategy is proposed for the diode clamped three-level inverter,which reduces the common-mode voltage output from 1/3 of DC bus voltage to 1/6 of DC bus voltage.The negative small vectors are divided into transiting small vector,additional small vector 1 and additional small vector 2,and the selection criteria of optimal small vector is derived according to the control ability of the neutral point voltage under different vectors,in order to effectively control the neutral voltage.The effectiveness of the common-mode voltage mitigation strategy and the neutral point voltage control strategy are verified by the experiments under two typical conditions of pure inductor load and unity power factor.%针对二极管箝位三电平逆变器,根据小矢量作用时中点电流与相电流方向,将小矢量分为正小矢量和负小矢量,提出一种不合正小矢量的脉宽调制矢量合成策略,将逆变器输出共模电压幅值由原来的1/3直流母线电压降低到1/6直流母线电压.将参与输出电压合成的负小矢量按照矢量合成关系分为过渡小矢量、附加小矢量1和附加小矢量2,并根据不同小矢量作用时对中点电压的控制能力推导出最优小矢量选择标准,实现对中点电压的有效控制.通过试验验证了纯电感负载和单位功率因数2种典型工况下共模电压抑制策略与中点电压控制策略的有效性.