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1. (WO2018122002) A MODULATION METHOD AND APPARATUS BASED ON THREE-PHASE NEUTRAL POINT CLAMPED INVERTER

Pub. No.:    WO/2018/122002    International Application No.:    PCT/EP2017/082881
Publication Date: Fri Jul 06 01:59:59 CEST 2018 International Filing Date: Fri Dec 15 00:59:59 CET 2017
IPC: H02M 7/487
Applicants: SMA SOLAR TECHNOLOGY AG
Inventors: WU, Zhaojin
LI, Shijun
ZHANG, Chao
WU, Zhaomi
Title: A MODULATION METHOD AND APPARATUS BASED ON THREE-PHASE NEUTRAL POINT CLAMPED INVERTER
Abstract:
Embodiments of the present invention disclose a modulation method and apparatus based on a three-phase neutral point clamped inverter. The method includes outputting a control signal for controlling all the switch elements of one of the three bridge arms to be in a non-conducting state, controlling states of the switch elements of the other two bridge arms to make the three-phase neutral point clamped inverter output a single-phase signal, wherein the two bridge arms are referred to as a first single-phase bridge arm and a second single-phase bridge arm, when controlling both switch elements connected to the first input end and switch elements connected to the second input end in the first single-phase bridge arm and the second single-phase bridge arm to be in the non-conducting state, controlling two of the other switch elements in the first single-phase bridge arm and the second single-phase bridge arm to be in a conducting state to provide a freewheeling loop for an inductive current of the inverter. The scheme provided by the embodiments of the present invention has relatively small current ripples, smaller switch tube loss and smaller inductor loss, improving efficiency of the inverter.