This book presents the control of multilevel inverter at low switching frequency using Selective Harmonic Elimination Technique.The non-linear transcendental SHE equations set which is formed in control of three-phase CHB 11-level inverter are attempted to solve by using a deterministic method like Newton Raphson method and stochastic optimization techniques like Continuous Genetic Algorithm and Modified Species based Particle Swarm Optimization.Finally,an effective, rugged, most efficient algorithm with less computational burden to solve SHE equations set during the complete range of modulation index from 0 to 1 with an aim of minimizing lower order harmonics has been developed. To validate the effectiveness of proposed MPSO technique, experiments have been carried out on a low power prototype of three-phase CHB 11-level Inverter and FPGA based Xilinx¿s Spartan-3A DSP Controller has been used to generate gating signals. The results of the experiments proved that MPSO technique has been successfully solved SHE equations set overall range of modulation index from 0 to 1, the %THD obtained over a major range of Modulation index also satisfied IEEE 519-1992 harmonic guidelines too.