Selective Harmonic Elimination in Cascade H-bridge Multilevel Voltage Source Inverters Using A Hybrid Optimization Algorithm

To eliminate harmonics from output voltage waveforms of a multilevel voltage source inverter, the pulse width modulation (PWM) technique for selective harmonic elimination (SHE) can be performed at a low switching frequency, which reduces switching losses and increases the energy conversion efficiency in medium voltage and high power applications. The SHE strategy provides the optimal output voltage by maintaining the desired fundamental voltage component while eliminating lower order harmonics. This paper presents a hybrid optimization method based on the combination of the genetic algorithm (GA) and the simulated annealing (SA) to achieve a faster and more accurate optimal solution for the harmonic elimination problem. The advantages of the proposed hybrid algorithm compared to some other optimization methods include the speed that reaches the global minimum and the acceptable convergence rate considered in the performance analysis of the inverter. Simulation results show the superiority of the proposed hybrid algorithm by comparing with either GA or SA alone.