Research on modulation wave of multilevel inverter based on 3-D space rectangular coordinate system

Research on three-phase multilevel inverter modulation wave based on the 3-D space rectangular coordinate system is presented in this paper, and the definition and characteristics of 3-D modulation wave vector and new research method is presented as well. Analytical expressions of SPWM and SVPWM can be obtained with modulation wave vector, which makes the modulation method, control strategy and the main circuit model can be analyzed and modeled in unified form. The judge condition for over modulation is presented as well. Proposed method is correct, clear, intuitive, easy to calculate, which is proved to be correct by simulation and experiment.