Abstract：Sigma-Delta converter can optimize the spectrum of the inverter and decrease the noise of the system in the modulation strategy of multi-level inverter. However, when using in the open-end winding induction motor fed by dual two-level inverters with common DC link, the traditional modulation strategy by changing short vector operation time to eliminate zero-sequence voltage is not applicable, because of the unfixed switch state and switch frequency. In this paper, a novel modulation strategy for dual two-level inverters with common DC link is proposed. The proposed method uses oversampling and noise shaping technology of Sigma-Delta modulator to optimize the voltage spectrum of the inverter. Meanwhile, according to the principle that the corresponding zero-sequence voltage value of two equivalent basic vectors is zero when the two vectors have a phase difference of 120° in two-level space vector diagram, the reference vector can be decomposed into two equivalent vectors generated by two inverters respectively with equal magnitude and an angle different of 120°. The proposed method can eliminate the value of zero-sequence voltage in dual two-level inverter with common DC link absolutely. Simulation and experimental results have verified the proposed method.
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2017, Vol. 32 
