VIENNA整流器中点电位平衡控制策略研究

Research on midpoint potential balance control strategy of VIENNA rectifier

针对三相三电平VIENNA整流器存在的中点电位波动问题,文章在传统载波移相调制技术(CPS-PWM)的基础上进行改进,提出一种14脉波的中点电位平衡控制策略。根据等效电路分析VIENNA整流器工作原理,根据空间矢量调制原理分析载波移相调制过程,确定中点电位不平衡原因,根据面积等效原理通过高频PWM异或控制脉冲实现分解冗余和非冗余矢量成分,并设立中点电位补偿系数D调节分解比例,保证中点电位平衡。实验结果表明,提出的控制算法不仅平抑中点电位波动、稳定直流侧输出电压,还降低了网侧电流畸变,且原理简明易于实现。

Aiming at the problem of midpoint potential fluctuation in three-phase three level VIENNA rectifier,this paper proposed the control strategy of 14 pulse carrier phase shift modulation and midpoint potential balance control on the basis of the improvement of traditional carrier phase shift modulation(CPS-PWM).Firstly,the working principle of VIENNA rectifier is analyzed based on the equivalent circuit.Secondly,according to the analysis of the carrier phase shift modulation process based on the principle of space vector modulation,the cause of the neutral point potential unbalance is determined.Finally,the redundant and non-redundant vector components are decomposed by the high frequency PWM xor control pulse based on pulse area equal principle,and the compensation coefficient D is setting to regulate the decomposition ratio to achieve the balance of the neutral point potential.The experimental results show that the proposed control algorithm not only reduces the fluctuation of the midpoint potential,and stabilizes the output voltage of the DC side,but also reduces the distortion of the current side of the network and it is easy to be implemented.