A half-bridge mmc converter with redundant control and its control method

Abstract

The invention relates to a half-bridge MMC converter with redundant control and a control method thereof. When a certain module fails, the output voltage will not be temporarily distorted and the converter is prevented from being blocked. The converter includes three phase units; each phase unit includes two bridge arms and two bridge arm reactors, and the bridge arm reactors are connected in series with the corresponding bridge arms; each bridge arm is composed of n half-bridge sub-modules Constituted in series, the number of n is greater than the number of k carriers of the bridge arm, and the phase difference between the carriers is π / k; wherein, n and k are positive integers; each of the half-bridge sub-modules consists of two IGBTs and A capacitor is connected in a half-bridge configuration. In the control method, the voltage equalization control of the internal capacitance of the bridge arm is realized by sorting the capacitor voltage, thereby avoiding the closed-loop control of the capacitor voltage, reducing the complexity of the algorithm, and reducing the occupation of computing resources.

Description

technical field [0001] The invention relates to the field of power conversion, in particular to a half-bridge MMC converter with redundant control and a control method. Background technique [0002] For converters with a large number of modules, the nearest level approximation modulation is generally used. At this time, due to the large number of modules, the output voltage waveform is better. However, for converters with a distribution voltage level, the number of modules is small. If the nearest level approach modulation is used, the waveform distortion of the output voltage is more serious, but if the carrier phase shift modulation is used, each module will correspond to a carrier (triangular wave), and the phase deviation between carriers is: π / n. When a module fails, the value of n will change accordingly, resulting in a change in the phase between the carriers, which will cause a temporary distortion of the output voltage after the module fails, and in severe cases wil...

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Problems solved by technology

When a module fails, the value of n will change accordingly, resulting in a change in the phase between the carriers, which will cause a temporary distortion of the output voltage after the module fails, and in severe cases will lead to a change in the output voltage. flow block

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