Combination method of gamma components in three-level three-dimensional SVPWM (space vector pulse width modulation)

Abstract

The invention discloses a combination method of gamma components in three-level three-dimensional SVPWM (space vector pulse width modulation). According to the method, based on three-level three-dimensional SVPWM, a two-dimensional vector space is divided into an outer-layer zone, a middle-layer zone and an inner-layer zone from outside to inside; different vectors are selected according to the features of vector combination in each zone to combine gamma components; the action time of positive and negative small vectors is calculated through adopting a more accurate method, and the accuracy of the combination of the gamma components can be improved. The method has the advantages of clear processes, simplicity and convenience in implementation, high efficiency, large modulation range and high modulation precision. The combination method of the invention can be realized in a digital controller easily.

Description

technical field [0001] The invention relates to a method for synthesizing gamma components in a three-level three-dimensional SVPWM, belonging to the technical field of power electronics. Background technique [0002] In APF or SVG products, such as figure 1 As shown, the neutral point clamp (NPC) three-phase three-wire three-level topology is often used. This topology needs to synthesize the vertical axis in the three-level SVPWM when the DC side bus capacitor voltage is equalized or with unbalanced loads. The coordinate γ means that SVPWM modulation needs to be performed in three-dimensional space. [0003] Such as figure 2 As shown, the single-phase NPC three-level topology can output three levels for each phase: +Udc, 0 and -Udc (Udc is the DC bus capacitor voltage), and for the three-phase three-level topology there will be 3 3 = 27 switch vectors, these 27 switch vectors form a three-phase three-level vector space. The abc coordinates of the three-phase voltages ...

AI Technical Summary

Problems solved by technology

The three-level two-dimensional SVPWM modulation synthesizes only the projection of the reference vector (α r ,β r ), without synthesizing γ r coordinates, when the existing three-level three-dimensional SVPWM modulation synthesizes the γ coordinates, it only synthesizes the γ coordinates by allocating the action time of a pair of positive and negative small vectors, without taking into account the γ coordinates of other action vectors, so its modulated The accuracy is not high, and because the gamma coordinates of other vectors are ignored, the modulation range will be reduced to a certain extent

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