373 / 2018-03-29 23:15:56

Variable Switching Frequency PWM Strategy for Three-Level NPC Converter Based on Peak Prediction of Current Ripple

全体主题 > Applications in renewable energy and storage, transportation, industrial drives, and grid power

Three-level Neutral-Point-Clamped (NPC) converters with pulse width modulation (PWM) strategy are one of the most widely used multi-level converters.Totally, constant switching frequency PWM and variable switching frequency PWM are the two most commonly used PWM strategies. Among them, variable switching frequency PWM can achieve better current performance due to the freedom of switching frequency. In this paper, the current ripple of three-level NPC converters is analyzed based on equivalent source theorem and the analytical current ripple expressions of three-level NPC converters corresponding to 27 different space voltage vectors are obtained. Based on theoretical analysis, a novel variable switching frequency PWM strategy with THD optimization of output current is proposed by setting the current ripple peak within a certain value. At last, the correctness of the theory in this paper is verified by simulation results.[This work was supported in part by National Natural Science Foundation of China (51507140); State Key Laboratory of Electrical Insulation and Power Equipment (EIPE17209); Xi'an Beilin District Science and Technology Project(GX1622), Operation fund of Guangdong Key Laboratory of Clean Energy Technology (2014B030301022), Open Research Fund of Jiangsu Collaborative Innovation Center for Smart Distribution Network, Nanjing Institute of Technology (XTCX201703),Specialized Research Fund for the Doctoral Program of Xi'an University of Technology(103-400211421)
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