Generalized Carrier PWM Algorithms For Multilevel Inverters With Unbalanced DC Voltages

This paper presents generalized carrier PWM algorithms for balancing load voltages for NPC multilevel inverters while dc-voltage sources are unbalanced or oscillating. Simplicity of algorithms, possible applying to any level inverters are the advantages of the proposed PWM method. The ability of separate control of PWM modes, dc voltage balancing (common mode) and ac voltage balancing in a carrier PWM modulator presents an another favorable feature. The validity of algorithms has been demonstrated by simulation