Pulse width modulation AC/DC converters with line current harmonics minimisation and high power factor using hybrid particle swarm optimisation

A hybrid optimisation method based on the combination of the particle swarm optimisation (PSO) method and the Newton´s method is proposed for optimised control of a voltage source three-phase three-level AC/DC converter. Three control objectives are considered: minimising the total harmonic current distortion (THD), maintaining high power factor (PF) and keeping the DC-link voltage at a reference value. The switching time of the pulse width modulation (PWM) AC/DC converter is determined by using the proposed method. It is observed that PSO has more possibilities to explore a large space and therefore offers a near optimal solution and the Newton´s method is used to fine tune the solution obtained by PSO. The proposed method is also applied to selective harmonic elimination (SHE) problem. Simulation results verify that harmonic distortion obtained by the proposed control scheme is lower than that of SHE techniques and natural sampling PWM (NS-PWM) method. Experimental results are presented to demonstrate the validity and efficiency of optimised control strategy.