基于钳位方式切换的Vienna整流器载波断续脉冲宽度调制策略

Carrier-based Discontinuous PWM Strategy Based on Clamp Mode Switching for Vienna Rectifiers

当Vienna整流器工作在直流电压不平衡条件下时,传统载波断续脉宽调制(carried-based discontinuous pulse-width modulation,CB-DPWM)会增加输入电流谐波和中点电压波动。为解决上述问题,提出一种基于钳位方式切换的CB-DPWM策略。为了减小输入电流谐波,根据变化的电压矢量对子区域和零序分量进行重新划分和计算。据此,建立统一的CB-DPWM调制波,分析可运行区域,得到直流电压不平衡度和可运行区域成反比的结论。结合中点电流分析不同钳位方式对中点电压大小的影响,并根据直流电压不平衡度的大小实时切换钳位方式,从而有效地减小中点电压波动。通过钳位区域判断和优化开关序列,减少切换钳位方式引入的开关动作,提高了Vienna整流器效率。最后,在Vienna整流器实验平台上验证所提策略的有效性。

When a Vienna rectifier operates at unbalanced DC-links,the traditional carried-based discontinuous pulse-width modulation(CB-DPWM)increases the input current harmonics and the neutral point voltage fluctuation.To solve the above problems,a CB-DPWM strategy based on clamp mode switching is proposed.To reduce the input current harmonics,the subsectors and the zero-sequence components are redivided and calculated according to the modified voltage vectors.Then,the uniform CB-DPWM modulation wave is obtained,and the operation region is analyzed,which is in inverse proportion to the unbalance degree.Furthermore,the influences of different clamping modes on the neutral point voltage are analyzed based on the neutral point current.According to the unbalanced degree,the clamping modes are switched in real time to reduce the neutral point voltage fluctuation.At the same time,the switching action introduced by the clamp mode switching is reduced by the switching sequence optimization and clamp region judgement,which can improve the efficiency of Vienna rectifier.Finally,the effective of the proposed strategy is verified on a Vienna rectifier experimental platform.