Space vector pulse width modulation of multilevel inverters: A new method for selecting the appropriate small hexagon

This paper proposes a simple and robust approach to apply the space vector modulation on multilevel inverters. The identification of the adequate triangle in space vector modulation algorithms becomes more complex as the inverter´s level increases. Therefore, the problem can be reduced to the selection of a two-level hexagon among many in any sector of the space vector diagram of N-level inverter. The criterion used to select the appropriate hexagon is the minimum distance between the tip point of the reference voltage vector and the center of the hexagon. Once the appropriate two-level hexagon is selected, all the remaining procedures necessary for N-level SVPWM method are thereafter done like conventional two-level inverter. Numerical simulation carried out for three, five and seven level cascaded H-bridge inverters confirms the effectiveness of the proposed method.