Research on equivalent relations between two kinds of SVPWM strategies and SPWM strategy for three-level neutral point clamped converter

Modulation strategy is one of the key issues of three-level neutral point clamped (NPC) converter. In allusion to the complicated implementation of space vector pulse width modulation (SVPWM), based on the three-level sinusoidal pulse width modulation (SPWM) strategy and the basic principle of SVPWM strategy the fast equivalent implementation algorithm of two kinds of three-level SVPWM strategies, namely the modulation-wave equivalent algorithm and the turn-on time equivalent algorithm, are proposed. The modulation-wave equivalent algorithm researches the equivalent modulation-wave under three-level SVPWM strategy, and through the turn-on time of each switch transistor controlled by three-level SPWM the turn-on time equivalent algorithm calculates corresponding conducting time of each switch transistor under three-level SVPWM strategy. Results of both simulation and experiments show that the proposed two kinds of three-level SVPWM strategies possess the advantages of simple implementation, short computing time, and the obtained results are more accurate.