PWM optimisation for three-level voltage inverter based on clonal selection algorithm

A clonal selection algorithm (CSA) is first applied to determine the switching time for a three-level voltage pulse width modulation (PWM) inverter. To obtain an optimal PWM switching pattern, CSA should calculate a set of nonlinear transcendental equations with nonlinear equality and inequality constraints. Unlike the general CSA by penalising infeasible solutions, this new CSA deals with constraints and guides the search to the true optimum solution by an infeasibility degree with a random disturbance (IFDD) selection operation. The proposed method minimise the total harmonic distortion and generates a waveform with adjustable amplitude of the fundamental component. Calculation results verify that the proposed method is efficient to obtain the optimal PWM switching pattern and is superior to natural sampling and genetic algorithm-based PWM switching pattern.