Harmonic Mitigation in a Multilevel Inverter with the Newton Raphson Method and the Particle Swarm Optimization

Proper switching angles in a cascaded H-bridge multilevel inverter lead to the reduction of harmonics in the output voltage waveform. These commutation angles can be obtained by the selective harmonic elimination method which provides nonlinear equations that are normally solved by the Newton Raphson method. In this article, a comparison is made between Newton Raphson's method and the Particle Swarm Optimization method, and the commutation angles obtained for a five-level and seven-level cascade H-bridge multilevel inverter were experimentally verified in a laboratory prototype.