An optimum PWM Strategy for 5-level active NPC (ANPC) converter based on real-time solution for THD minimization

The recently introduced active NPC (ANPC) converter is becoming an attractive topology of multilevel converter family. This paper presents the analysis of the 5-level ANPC converter with an optimum PWM strategy to achieve the minimized total harmonic distortion (THD) for high power or high frequency applications. Instead of relying on the conventional look-up table based on off-line calculated solutions, the switching angles of the optimum PWM are calculated through a real-time algorithm, which is time-efficient and therefore easy to implement in real-time by digital processors. The control scheme of balancing the floating capacitors voltages is also proposed. Simulation results verify the performance of the proposed strategies.