Carrier-based Discontinuous PWM Strategy Based on Clamp Mode Switching for Vienna Rectifiers
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.
Vienna rectifierunbalanced DC-linkscurrent harmonicsneutral point voltage fluctuationcarried-based discontinuous pulse-width modulation(CB-DPWM)switching sequence optimization
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