Near optimal approach in the design and implementation of multilevel voltage source inverters

In most literature, the increments at each voltage step in a multilevel voltage source inverter are treated as identical. This approach may simplify the design of the inverter in both software and hardware while compromising the quality of the output power. Various schemes for searching the optimal voltage amplitudes and switchng angles for each of the individual voltage steps are studied. A near optimal scheme is investigated and compared with the optimal one. It is found that the near optimal pattern has almost the same level of harmonic distortion as the optimal one. Unlike the optimal pattern, which involves complicated calculations, the near optimal pattern can be easily generated in real time. The near optimal scheme is implemented using a TMS320 CSO digital signal processor. Experimental results show agreement with simulated ones.