Abstract:

This paper focuses mainly on the control method of neutral-point voltage balancing in the three-level inverter.A comprehensive mathematic model of three-level inverter is set up.A novel space vector modulation algorithm is proposed by using the nearest three vectors as the reference voltage vector.The judging rules of the small sectors and the out voltage vector sequence are presented.The duty time of each vector is also computed.The main factors for the neutral-point imbalance are discussed.A simple neutral-point voltage balancing control method,which only requires the direction information detection of each phase leg's current and neutral point voltage ripple,is proposed.The validity of the proposed method is demonstrated by the experimental results.

Key words: space vector pulse width modulation;three-level inverter;neutral point voltage balance