Modulation strategy is one of the important technologies of power electronic converter. Space vector pulse width modulation (SVPWM) has been widely used in the field of medium and low voltage motor speed regulation, especially the three-level converter based on NPC and NPP topology. The algorithm can get three-phase modulation wave through simple linear calculation and complete the calculation of duty cycle. The simulation results show that the algorithm is valid and correct by MATLAB / Simulink