Analysis And Study On SVPWM Method For Three-level Inverters

Multilevel converters have been widely used in high-voltage and high-power application fields. Among many of its modulation strategies, Space Vector Modulation (SVM) has been one of the most popular research points. The main advantages of the strategy are the following: it provides larger under modulation range and offers significant flexibility to optimize switching waveforms;it is well suited for implementation on a digital computer;it has higher DC voltage utilization ratio.The principle of three level voltage space vector PWM is deeply studied. The main point in this article is how to use space vector PWM technique in three level inverter. At mean time, the reason of unbalancing in neutral-point potential fluctuation is investigated.This paper have researched the topology of three level inverter, and discussed the principle of the three level inverter. This article discuss svpwm strategy used in two level inverter .For using SVPWM in three level inverter ,this paper propose two way of judging the place of reference vector ,and then introduce the way of computing the time of modulation. this paper introduces approach that can reduce switching loss .At the same time , The article proposes a novel SVPWM strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors.The new modulation approach shows superior performance for the harmonic voltage and the control of neutral-point potential. The main factor which influences neutral point voltage balance of three level inverter is deeply studied. Hence some way of balancing the neutral-point voltage are proposed. At last we simulate the SVPWM modulating means of three-level inverters by MATLAB, and prove the correction of modulating mean.