具有中点电位平衡的船用变频器三电平SVPWM过调制技术

摘要

The small vector duration time turns zero when a diode NPC three-level inverter runs into over modulation.The output voltage is generated from medium vector and large vector only.Therefore,conventional over modulation control method leads to unbalance and fluctuation of neutral point voltage.This paper proposes a novel there-level voltage source inverter,which uses the small vectors to control the neutral point voltage.In order to eliminate the neutral point unbalance and fluctuation,only the large vector is selected to generate the output voltage after the small vector duration time becomes zero.In the meantime,the output voltage amplitude is increased to follow the reference voltage.The proposed control method is verified by simulation result.%二极管钳位型三电平电压源逆变器在过调制区由于小矢量作用时间迅速减小为0,只有中矢量及大矢量输出,常规的过调制策略容易引起中点电位偏移与波动.并且由于常规过调制采用最小相角误差方法,导致较大幅值偏差.本文提出一种新的三电平电压源逆变器过调制方法,该方法利用小矢量调节中点电位,当小矢量作用时间减小为0之后,只选择大矢量输出,大大降低中点电位偏移与波动,同时增加输出电压幅值,使其与参考电压保持一致.仿真结果表明所提出方法的有效性和可行性.